y

Marine Biological Laboratory

R....ve^ ^^y 5, 1950

Accession No.

64200

Given By publisher and author
Place, _^

PROBI.EMS OF
MOKrilO(;ENESIS
IN CILIATES

The Kinetosotties in Development,
Reproduction and Evolution

ADVISORY BOARD
Biological Research Series

PAUL A. WEISS, Ph.D.
Professor of Zoology
University of Chicago

DAVID R. GODDARD, Ph.D.

Professor of Botany
University of Pennsylvania

FRANCIS 0. SCHMITT, Ph.D.
Professor and Head of the Depart-
ment of Biology
Massachusetts Institute of Technology

d

PROBLEMS OF
MORPHOGENESIS
IN CILIATES

The Kinetosomes in Development^
Reproduction and Evolution

Andre Lwoff

HEAD OF THE DEPARTMENT
OF MICROBIAL PHYSIOLOGY
INSTITUT PASTEUR, PARIS

1950

John Wiley & Sons, Inc., New York

Chapman & Hall, Limited, London

Copyright, 1950

BY

John Wiley & Sons, Inc.

All Rights Reserved

This hook or any part thereof must not
be reproduced in any form trithout
the written permission of the publisher.

PRINTED IN THE UNITED STATES OF AMERICA

"// y a lieu de se flatter que ees decouvertes produirotit plusieurs
bons effets. Elles doivent naturellement nous jeter daus une ffrande
defiance a regard de ces regies generates, auxqueltes, si je pais parler
airisi, on a pretendu borner ta nature et qui ne peuveni servir qua
mettre obstacle a nos connaissances.''

A. Trembley, "Memoires pour servir a I'histoire d'un genre de
Polype d'eau douce a bras en forme de cornes." J. et H. Ver-
beeck, ed. Leiden, 1744.

Foreword

The author had the privilege of delivering the Dunham
lectures at Harvard University during the academic year
1947-1948. One of the lectures, given under the title ''Visi-
ble self-reproducing cytoplasmic granules in the life cycle
of some parasitic ciliates," is the nucleus around which the
book has been built.

It was not possible, in the course of one lecture, to
discuss, or even to mention, all the aspects of the problems
raised by the ciliates. The author has therefore been
pleased to take the opportunity kindly offered by Doctors
Goddard, Schmitt, and Weiss, as advisory editors of the
Wiley Biological Research Series, of organizing some of
these problems into this monograph. He was especially
pleased because many of the data related to ciliates are in
perfect agreement with the theoretical conceptions of Dr.
Paul Weiss, chairman of the Advisory Board, concerning
what he has called "molecular ecology."

This monograph is not a treatise. No attempt is made
to cover all the aspects of the subject or to give an exhaus-
tive survey of the literature. The author's work on the
morphology and biology of the ciliates started in 1921 and
extended over many years. Having for some time followed
other roads, he has, nevertheless, the impression that a
somewhat aged and matured knowledge of the ciliates is
not without advantages. Ciliates are very nice animals in-
deed, but, like other delicate creatures, they have to be
treated with a buffered and balanced mixture of love and
experience.

The author expresses the hope that his American friends,
to whom this book is dedicated, will find some austere

vii

viii FOREWORD

pleasure in reading these pages, or, at least, in looking at
the pictures.

The difficulties which may be encountered by some Anglo-
Saxon readers may not necessarily result from inadequate
knowledge of their own language. They could be due in
part to the fact that the French author, owing to a certain
distrust of translations, has, despite his diffidence, written
this book directly in English.

The author is indebted to his friends E. Faure-Fremiet
and Jacques Monod for helpful criticisms and discussions.

Andre Lwoff

Paris, France
January, 1950

The author wishes also to thank the editors of the Archives
de zoologie experimentale et generate for kind permission to
reproduce Figs. 1 to 16, 19 (slightly modified) to 26, and
29. Figure 17 is taken from E. Chatton, A. and M. Lwoff,
and J. Monod, Compt, rend. soc. biol, 107 (1931); Fig. 18
from S. Villeneuve-Brachon, Arch. zool. exp. et gen., 82
(1940); Fig. 27 from E. Chatton, A. and M. Lwoff, and L.
Tellier, Coinpt. rend. soc. biol, 100 (1929) ; Fig. 28 (slightly
modified) from E. Faure-Fremiet, Bull. biol. France-Bel-
gique, 79 (1945); Fig. 30 from E. Chatton and J. Seguela,
Bull. biol. France-Belgique, 7 If. (1940); Fig. 31 from E.
Chatton and A. and M. Lwoff, Compt. rend. soc. biol., 107
(1931) ; and Fig. 32 from E. Faure-Fremiet and H. Mugard,
Compt. rend. acad. sci., 227 (1948).

Contents

Foreword vii

Chapter 1. Introduction of the Kinetosome Considered as
a Model of a Visible Cytoi)hisniic Unit En-
dowed with Genetic Continuity 1

Chapter 2. The Complicated Life Cycle of (lyiunodini-

oides inkystans 9

Chapter 3. How the Disarmed Tomite Proceeds to ^lanu-
facture Explosive Weapons in the Form of

Trichocysts 19

Chapter 4. Aspects of the Kinetosome 27

Chapter 5. Division, Absence of Division, Induced Divi-
sion, and Morphogenesis 36

Chapter 6. Genetic Continuity of Kineties and the Prob-
lems of Isolated Populations of Kinetosomes . 42
Chapter 7. Order and Disorder; Torsion and Detorsion . 52

Chapter 8. Problems of Equilibrium 61

Chapter 9. The Cortical Network of Suctorians; Repro-
duction and Organization 65

Chapter 10. Movements of the Ciliary System in Ontogeny

and Phylogeny 69

Chapter 11. Differentiation in Ciliates 73

Chapter 12. Interactions of ^Morj^hogenetic Units .... 78
Chapter 13. Ontogeny in Ciliates and the Differentiation

of Metazoan Cells 83

Chapter 14. The Kinetosome in Development, Morpho-
genesis, and Evolution 88

Bibliography 95

Index 99

'^ 64200

CHAPTER 1

Inlrocliictioii of tlir Kinrtosome
Consi(i(*rc(l as a Model
of a Visible Cytoplasmic Unit
Endowed with Genetic Continuity

Development of an animal is a complex process generally
considered as the result of interactions between a specific
protoplasm and hereditary outfit on the one hand, and a
complex set of environmental factors on the other. The
most important phenomena during this process are egg
cleavage and subsequent cell multiplication, cell move-
ments, differentiation, and modulation, the sum of which
results in the formation of tissues, organs, and organism.
Development is an epigenetic phenomenon. Starting from
an egg, which is a highly complicated cell, every organism
has to be elaborated at each generation. This is ontogenesis.

During development, different cell lines acquire different
properties. Differentiation is the process resulting in spe-
cialization of a cell as evidenced by its distinctive actual and
potential functions. It is by definition irreversible.

It is known that there is, in general, a marked antagonism
between cell differentiation and cell division, that some
highly specialized cells are unable to divide, that the devel-
opment of an animal from an egg is, as a whole, an irrevers-
ible process, that evolution itself is irreversible. It is known
also that the animal has, with a few exceptions, relegated
to the germinal hne the responsibility for the maintenance

of the species.

1

2 MORPHOGENESIS IN CILIATES

But Protozoa are, as stated by C. Dobell (1911), ''non-
cellular" organisms. A cell is a differentiated part of an
organism. Protozoa are complete individuals, whole organ-
isms, and behave as such. If one wants to remark the fact
that they generally have one nucleus, it is best to say that
they are monoenergid.

The fundamental morphological and biochemical similar-
ity of living beings makes it probable that some processes
of morphogenesis, differentiation, and evolution in Protozoa
must have something in common with the homologous proc-
esses in Metazoa.

How did the Protozoa, and especially the ciliates, manage
to reconcile the non-cellular state with such processes as dif-
ferentiation, development, morphogenesis, evolution, and
reproduction, some of which are antagonistic and irrevers-
ible? This is our main problem. It will be discussed in
terms of particulate phenomena.

Numerous data concerning development have led embry-
ologists to the conclusion that cell differentiation must be
attributed to the unequal distribution and segregation of
specific particulate material. ''During the development,"
writes R. Harrison (1937), "all movements, differentiation,
and in fact all developmental processes are actually effected
by the cytoplasm."

The importance of specific cytoplasmic units in the life
of organisms and especially in developmental functions
seems thus to be well recognized. Cytoplasm is not just a
collection of enzymes or a plastic and complaisant receptor
passively submitted to the dictatorship of genes, but cer-
tainly contains self-reproducing bodies endowed with speci-
ficity. And the geneticists have indeed concluded that some
specific determinants do exist in the cytoplasm and play
their role in heredity.

As a matter of fact, according to E. Caspari's review
(1948), some twenty cases of cytoplasmic inheritance have

KINETOSOME AS A VISIBLE CYTOIM.ASMIC UNIT 3

already been described. Many of tlicm deal with ihv prop-
erties of chl()ro]:)lasts, absent in animals. The i)hisnia^enes,
theoretically necessary for dev(dopni(Mit. are, so far, exceed-
ingly rare in heredity. Their j)reseii('e lias not Ixhmi demon-
strated directly; they have not been seen; and they remain
in the most irritating form of a logical hypothesis. It seems
therefore of utmost importance for the progress of biology,
and also of biochemistry, to develop this particulate con-
ception of cytoplasm.

While discussing the problems of modulation and differ-
entiation, Paul Weiss (1947) has tried to transcribe what
he calls ''the symbolic concepts of cells and protoplasm" in
terms of molecular phenomena and has introduced the con-
cept of "molecular ecology," according to which a cell is to
be viewed as an organized mixed population of molecules
and molecular groups.

Let us quote some of his propositions:

1. "Each population is made up of molecular species of
very different composition, sizes, densities, rank, and stabil-
ity, from trivial inorganic compounds to the huge and highly
organized protein systems. Some segments of these popu-
lations occur in relatively constant 'symbiotic' groupings,
often of a limited size range ; these form the various particu-
lates of the cell content.

2. 'Tt is one of the fundamental characteristics of cellu-
lar organization that the various species constituting the
population are not self-sufficient, but depend in various de-
grees upon other members of the population as well as upon
the physical conditions prevailing in the space they occupy.
Survival and orderly function of the total population are
predicated on the presence of all essential members in defi-
nite concentrations, combinations, and distributions.

3. "In view of this intricate interdependence, given mo-
lecular species can exist, and given interactions between
species can occur, only within a certain limited range of
conditions specific for each kind. We might call these con-

4 MORPHOGENESIS IN CILIATES

ditions the 'existential and operational prerequisites' for
each molecular species or group. The probability of mem-
bers of a given species to persist, hence to be found, in any
but the appropriate setting, would be extremely low.

4. ''If the specific existential and operational prerequi-
sites for the various molecular species and groups differ at
different sites of the cell, different species will automatically
become segregated into their appropriate ecological environ-
ments. As a result, even a wholly indiscriminate mixture
can become sorted out into a definite space pattern. Cer-
tain species will assemble in relatively stable combinations,
like biotic groups, while others, mutually incompatible, will
separate. '^

This is a beautiful concept. But it is a theory. Is it
possible to obtain some positive data concerning cytoplas-
mic units?

C. Darlington (1944) nas classified all biological cor-
puscles into three categories: (1) the nuclear system; (2)
the plastids of the green plants or corpuscular system; and
(3) what he has described as the "undefined residues of
heredity/' not associated with any visible body; this is the
"cytoplasmic" or "molecular" system whose constituents are
generally known as "plasmagenes."

"In order that we should find out something more about
these free plasmagenes/' writes Darlington in his classical
book, "we must try to form a more precise picture of how
they live, move, and multiply. It seems likely that they
are protein molecules or aggregates. Evidently, they are
such that, like true genes, they can arise only from proteins
of the same kind apart from mutations. Unlike true genes,
however, their reproduction is not controlled by a mechani-
cal equilibrium but will be subject rather to conditions of
chemical equilibrium genotypically controlled but specific
for each type of gene."

This is also an entirely hypothetical conception. When
we study viruses or enzymes, we enjoy the criteria of in-

KINETOSOME AS A VISIBLE CYTOPLASMIC UNIT 5

fection, disease, and specific cluMnical reactions, and, of
course, in some cases the control of electron microscopy.
No identified chemical reaction has l)een ascribed to any
plasmagene. How can we obtain a picture of the activity
of plasmagenes? The situation seems difficult to say the
least. But Nature does not like to be disregarded and rarely
forgives classifications. Among these ''undefined residues
of heredity" which are considered as invisible are perfectly
visible granules, cytoplasmic, specific, self-reproducing vis-
ible granules.

Thus we can approach directly the study of molecular
ecology. It is of course very advantageous to deal with in-
visible particles. We may organize them at will without
apparent danger. But w^hat will happen to the theory,
when, by chance, we are dealing with real visible granules,
the life history of which we are able to analyze? As will be
seen very soon, we are today in a position to perform this
analysis. Thus, we will find that, although molecular ecol-
ogy is a very clear, almost schematic, and very clever the-
oretical conception, it is nevertheless in excellent agreement
with the facts. Such abnormal events happen from time
to time. If Nature rarely forgives classification, she some-
times forgives theories.

In all animals or plants, at the base of each flagellum or
cilium, one sees a spherical corpuscle. These corpuscles
always reproduce themselves by division. They are "self-
reproducing" systems, and obviously cytoplasmic. Shall we
refer to them as "undefined residues of heredity" or as plas-
magenes? Why should we? Let us simply call them by
their name: "blepharoplasts" or "kinetosomes," and let us
first say a few words about the way protozoologists consider
these kinetosomes.

During cell division, a granule is present in the center of
the aster, which is the centriole or central body. When
spermiogenesis proceeds, the flagella arise from this cen-
triole. The centriole of animal cells is a lineal descendant

6 MORPHOGENESIS IN CILIATES

of the centriole of earlier cell generations^ probably back to
the egg.

In the flagellates, the flagellum arises from a granule

c

1

1

1

-tc.

cd. 1

/^m

■ »^

9^

tt^^B

1 ah 2

*

9

H ^ '

'* ' i

4,^

• ^

i^

«K

• • •

^.

• • «

•

^v '

» •• J

■f *

4>

^^Hp

* *# •

• s •

: :• :

* •• *

• ••

» • •

^1

s *

* * *

^r

• •*' •

• *• *

• •• •

* *

1 a
b

# ->

• •• • *.

• •* *i

• *•

C

•

a

Vrf.

1 ^ d
c.

e

Fig. 1. Aspects of kinetosomes. (a) The kinetosomes of kinety a of
Gymnodinioides (tomont) dividing in order to form kinety b. (b) The
kinetosomes of kinety 1 of Foettingena (tomont) producing kinety a.
(c) Kineties of Gymnodi7iioides (tomite), showing the kinetosomes (c.)
at the left (right of the observer) of the kinetodesma (cd.). Each
kinetosome has a large satellite corpuscle and is connected by a desmose
to a daughter kinetosome (tc.) which is a trichocystosome, (d) Kinety
of Polyspira (protomont), showing the formation of trichocysts (t.)
from the trichocystosomes (tc). (e) Last division of Foettingeria.
Formation of the kinetosomes of the future kineties b and c by

the kinetosome of kinety a.

called a blepharoplast or kinetosome. In some cases, this
kinetosome participates in the nuclear division, but this
participation is often unnecessary. In many cases, the nu-
cleus and kinetosome divide independently.

KIXETOSOME AS A VISIBLE CYTOPLASMIC UNIT 7

It is generally stated that the contriole of animal cells
may give rise to flagclla and behave like a ble]ihar()]:)]ast
or a kinetosome. According to E. Chatton (1924 and 1931),
this proposal must be inverted. The centriole is phylo-
genetically and primarily the organelle giving rise to the
fiagellum. It may, in some cases, participate in nuclear
division. Every centriole is a kinetosome, but every kineto-
some is not a centriole.

The careful study of hundreds of flagellates has revealed
that the kinetosome is always formed by the division of a
pre-existing kinetosome. It is endowed with genetic con-
tinuity, and its existence has been demonstrated even in
non-motile stages of the life cycle. This kinetosome gives
rise to the fiagellum. It is able to multiply independently
of the nucleus, thus giving rise to chains of kinetosomes.
The careful study of numerous ciliates has shown that the
kinetosomes of ciliates are also endowed with genetic con-
tinuity. Even in forms which are devoid of cilia during a
long period of their life cycle, the kinetosomes may often
be seen organized, forming what we have called with E.
Chatton and M. Lwoff (1929) an ^^infraciliature." And the
kinetosomes of the ciliated "embryo" will be formed from
these pre-existing kinetosomes. But kinetosomes are not
only able to divide and to produce cilia. They are able to
secrete fibers, to give rise to other granules producing
trichocysts or trichites.

They play a prominent role in development, differentia-
tion, and morphogenesis of ciliates. They move and vary
constantly.

These cytoplasmic organelles, endowed with genetic con-
tinuity, live in a genetically constant system, thus providing
a beautiful model of a self-reproducing particle whose activ-
ity is controlled by its environment [c/. A. Lwoff (1949b)].

My intention is to study the behavior of kinetosomes
during the life cycle of some ciliates, to analyze and to dis-
cuss the various aspects of their movements and activity

8 MORPHOGENESIS IN CILIATES

in development, differentiation, division, and evolution.
The reader will be perhaps badly shocked by some repeti-
tions. But it was not possible to describe morphological
phenomena without a single mention of the problems raised,
and it was also felt that the theoretical implication of each
set of data should be considered separately. Repetitions are
the inevitable consequence of this procedure, the counter-
part of which should be clarity.

CHAPTER ^

The Complicated Life Cycle
of Gymnodhiioides inkystans

We are now in a position to consider some apostomatous
ciliates.* This is a very homogeneous group, primarily
associated with Crustacea. Many of these ciUates have two
hosts. All have very remarkable and unique properties.
They show a complicated life cycle, each phase of which is
characterized by a peculiar structure that is the conse-
quence of important movements of the ciliary system. On
the gills of the hermit crab, Eupagurus hernhardus, are nu-
merous cysts of the ciliate Gymnodinioides inkystans. This
is the phoretic phase or phoront. Excystation occurs only
at the molt of the host, and the small ciliate penetrates the
discarded exoskeleton. This is the trophic stage or tro-
phont. In 6 to 10 hours the cihate has increased its volume
up to 32 times. The trophont then escapes from the exo-
skeleton and after some hours encysts and divides. Let us
call this stage tomont. The small ciliates or tomites thus
formed escape from the cyst and swim actively. They may
enjoy a free life for 6 to 8 days. If they find a crab, they
encyst on the teguments; if not, they die.

The trophic phase corresponds to the ingestion and con-
centration by the ciliate of the violet astacin-protein of the
crab. During this phase, the cytoplasm of the trophont is

*A11 the data on these cihates are taken from E. Chatton and A.
Lwoff's extensive monograph (1935). A good summary of this work
has been given l)y H. B. Kirby in Calkins and Summer's book, Protozoa
in Biological Research.

9

10

MORPHOGENESIS IN CILIATES

reduced to a thin peripheral layer containing the macro-
and the micronucleus. When the fully grown ciliate leaves
the molted exoskeleton, expansions of the cytoplasm divide
the accumulated food.

Phoront: Phoretic metamorphosis

Tomite

Young
trophont

Fig. 2. GymnGdinioides inkystans: life cycle.

The single enormous ingested lump is then reduced to
ellipsoidal platelets. These reserves are consumed during
the phoretic phase, which may last some months, until the
ecdysis of the host takes place. When the reserves are di-
gested, they first turn pink, owing to the separation of the
astacin from the protein, and finally astacin is precipitated
as small red granules. It is worth mentioning that reserves

LIFE CYCLE OF GYMXODIXIOIDES INKYSTANS 11

may remain undigested for weeks or even months, thus pro-
viding a unicjue example of the persistence of a protein in a
foreign protoplasm.

What is the intimate structure of these ciliates? The
troi)hic phase, as it may be seen after silver impregnation,
shows nine rows of cilia diverging from the anterior pole or
its vicinity. Each of these rows has a given pattern, con-
stant for the species. Four short rows are present in the
equatorial sector of the ciliate. The rosette or mouth organ,
not represented on the scheme, is located at the anterior end
of the rows x, y, z. Each of the ciliary rows or kinety
has a line of kinetosomes. At their right, the right of the
ciliate (which corresponds to the left of the observer), is
a fine thread w^hich underlines the line of kinetosomes. In
all ciliates, this kinetodesma is always at the right of the
kinetosomes. This is the law of desmodexy [E. Chatton,
A. Lwoff (1935b)]. The kinetodesma is probably an asym-
metrical structure. Its relation to the kinetosomes is not
yet clear.

'After encystment, the ciliate undergoes a detorsion ac-
companied by an elongation of the rows a, x, y, z, which is
essentially due to rapid divisions of the kinetosomes.

But, whereas in the row^s x, y, z the kinetosomes remain
in line, the kinetosomes of a divide tow^ards their left.
These granules become lined in a new row h.

It is clear enough that the course and the length of the
rows depend on the phase of the life cycle.

It is clear also that the division of kinetosomes is induced
by some changes in the underlying cytoplasm. The sim-
plest hypothesis is, for the time being, that growth of the
kinetosomes and their subsequent division depend on the
presence of some specific foodstuffs. We may consider also
the hypothesis that, when kinetosomes are too numerous to
be lined in one row, they invade the adjacent space where
they form new lines. All these interpretations wull be con-
sidered later on.

12 MORPHOGENESIS IN CILIATES

Once the detorsion is achieved, the ciliate has a bipolar
set of nine rows plus the rows a, b and x, y, z. It will now
undergo a series of repeated divisions: this is palintomy.

Fig. 3. Gymnodinloides inkystans. (a) The trophont. (b) The to-
mite (p. 13). The trophont's volume may be 2 to 64 times that of
the tomite. c.a., "cadre anastomotique": a characteristic fiber of many
apostomatous cihates, always located between kineties 2 and 3; r.,
rosette or month organ; ch.f., falciform field (thigmotactic) ; ch.og.,
ogival field (also thigmotactic); g.i., infraciliary grannie (kinetosome);
tc, trichocystosome ; t., trichocyst.

LIFE CYCLE OF GYMXODIXIOIDES INKYSTANS 13

During these divisions, all the rows remain bipolar, except
the system .t, ij, z. The anterior and posterior parts of this
system disappear before each division, and only three short
segments remain in the equatorial part. The kinetodesma,

Fig. 3b.

as well as the kinetosomes, disappears, as if the maintenance
of the kinetosome, as well as its growth and division, de-
pended on the properties of the underlying cytoplasm. As
we shall see, this conclusion will be reached frequently.

Divisions continue. One more ciliary row, c, has been
formed. The division stops when the size of the tomites is
reached. This happens after one to five divisions, according

14

MORPHOGENESIS IN CILIATES

Fig 4 Gymnodinioides inkystans. (a) Trophont. (b), (c), (d), (e)

Protomonts. (f) Tomont. Note the detor.ion of the cihature, the

elongation of kmeties a, x, y, z; in the tomont (f), reduction of x, y, z

in the interval of two divisions.

LIFE CYCLE OF GYMNODINIOIDES INKYSTANS 15

to the importance of growth at the trophic phase, thus
yielding two to thirty-two toniites.

Important changes take place during this last period.

Fig. 5. Gymnodinioides inkystans: palintomy. (a) Two tomonts.
(b) Eight tomonts. (c) Sixteen protomites.

The rows x, y, z are progressively reduced in size. However,
an anterior segment of x has been detached which will give
rise to the primordium of the rosette or mouth organ. A
part of the rows h and c gradually becomes condensed in a

16 MORPHOGENESIS IN CILIATES

small field of granules, which disappear. The row a gives
rise to another ellipsoidal field.

While these processes are on the way, the middle part of
the rows 8 and 9, kinetodesma and kinetosomes, disappears.
The kinetosomes of the anterior part undergo one division.
But the tomite is not yet ripe. In order to be ripe, the two
granules of the row 9 have to divide once more, thus giving
four rows of granules.

During the early period of tomitogenesis cilia have ap-
peared. They are not represented on the drawings. They
are ordinary cilia, all over the body. However, the rows 8
and 9 and the field a produce specialized thigmotactic cilia
which have the property of ceasing their movements when
coming into contact with a solid surface, thus assuring ad-
herence to the substrate. This important patch of special-
ized cilia will allow the tomite to attach itself and to encyst
on the integument of the crab.

Let us now imagine a morphologist looking at the living
tomite and considering these specialized cilia without know-
ing their origin. His conclusion would be that the forma-
tion of this specialized structure is the result of the action
of an organizer.

Dalcq and Pasteels, explaining the neural induction, pos-
tulate a multiplication of particles in the neural system
under the influence of an organizer, and compare these gran-
ules with a virus. An agent possessing the ability to induce
multiplication of such granules would be, according to
Dalcq and to Brachet, an ''evocator." This conception ap-
plies very well to the formation of the thigmotactic field,
with the difference that we see the granules really multi-
plying. There is of course no reason to refer to self -repro-
ducing cytoplasmic units as viruses.

Before escaping the cyst, the tomite has to form tricho-
cysts, but this phenomenon will be examined later on.

When analyzing development, embryologists have found
that the original control of differentiation in all cases ap-

LIFE CYCLE OF GYMNODINIOWES INKYSTANS 17

pears to be exerted in relntion to what may be called a
morphogenetic fipld.
According to J. Huxley and G. de Beer (1934), "The

Fig. 6 Gymnodinioides inkystam: tomitogenesis. ' Formation of th^
og.val field ich.o,.) from „. Mig„t,on of 6+c. Dijp In e o
the median part of 8 and 9. Isolation of a sector of x r' M l
gomg to form the rosette (see the complete tomite on F,. 3b

18 MORPHOGENESIS IN CILIATES

term field implies a region throughout which some agency
is at work in a coordinated way, resulting in the establish-
ment of an equilibrium within the area of the field." "A
field," says Waddington, ^^is a system of order such that the
position taken up by unstable entities in one portion of the
system bears a definite relation to the position taken up
by the unstable entities in other portions."

The region between the rows 7 and 1 corresponds to such
a field. The kinetosomes behave differently according to
their position. Their maintenance, or their growth and
division, depend evidently on the properties of the under-
lying cytoplasm.

The simplest hypothesis, for the time being, is that kinet-
osomes must get some specific food in order to grow and
divide, and that the specific food must be unequally dis-
tributed in the region between the rows 7 and 1. In terms
of molecular ecology one should question also the possible
role of some specific cytoplasmic particles which could be
directly or indirectly responsible for the nursing of kineto-
somes.

CHAPTER tj \^v -^ yi

How the Disarmed Tomite Proceeds
to Manufacture Explosive Weapons
in the Form of Trichocysts

We have considered only what we may call ''normal'^
kinetosomes, able to produce cilia. But kinetosomes may
acquire new properties.

Until the end of tomitogenesis, the structure of the ciliary
row is simple. The kinetodesma is at its right. At the left,
we see the kinetosomes with the cilia and another corpuscle,
sometimes called the ^'kinetoplast/' which is produced to-
gether with the cilia and represents perhaps only the en-
larged basis of the cilium itself. But at the end of tomito-
genesis, all the kinetosomes divide. The daughter granule
is produced on the left in all the rows, except in the thig-
motactic field of 9, where it is produced at the right.

These daughter granules do not produce cilia. They form
a cylindrical rod which elongates towards the inside of the
ciliate. These organelles are capable of being extruded
under the influence of certain stimuli; they are trichocysts.

The formation of trichocysts has, for a very long time,
been obscure. All possible origins have been assigned to
them: nucleus, vacuoles, mitochondria, superficial network;
all except the right one. This confusion was due to the fact
that trichocysts are generally formed at any moment. In
Gymnodinioides, they are formed at only one phase of the
life cycle [E. Chatton, A. and M. Lwoff (1931b)]. The
picture is very clear, and it is perhaps necessary to state
that its diagrammatic representation corresponds to what is

19

20 MORPHOGENESIS IN CILIATES

really seen under the microscope. It is obvious that each
trichocyst is generated by one granule and that this granule
results from the division of a kinetosome. Here, we are
faced with an important phenomenon. The kinetosome has
not only the properties of growth, division, and the produc-
tion of cilia. It has also other possibilities or. as embryolo-

Fig. 7. Formation of trichocysts and trichites. (1) Gymnodinioides:

(a) The normal ciliary row. Kinetosomes c and satellite corpuscles s.
The kinetodesma is at the right of the kinetosomes (desmodexy).

(b) Division of the kinetosomes; trichocystosomes are produced, (c)
Formation of trichocysts in Gymnodinioides. (2) Formation of tricho-
cysts in Polyspira. (3) Formation of trichites in Foettingeria.

gists would say, prospective potencies. A cilium-bearing
kinetosome may, under certain circumstances, divide and
give rise to a new granule which will not produce cilia but
trichocysts. A granule never produces a cilium and a tricho-
cyst. It produces either a cilium or a trichocyst.

We have reached the conclusion that kinetosomes may
divide and produce cilia. We see that the ultimate phase
of tomitogenesis reveals a new potency of the kinetosome.

Let us now recall the conclusions arising from the study
of Gymnodinioides. Growth, division of the kinetosomes,
production of cilia, production of trichocysts depend on the
position of the granules on the ciliate and on the phase of
the life cycle. And it is perfectly clear that the "position"
or the "phase" is not a metaphysical property. It is obvious
that growth, division, and metabolism of kinetosomes, as
revealed by the production of cilia or trichocysts, depend on
the properties of their environment.

HOW TOIVIITE MANUFACTURES TRICHOCYSTS 21

The study of other forms of apostomatous ciliates will re-
inforce these conclusions and provide more data about
kinetosomes.

Phoront

Tomite

Protomite

Grown-up
trophont

Fig. 8. Polyspira delagei: life cycle.

Polyspira delagei lives as a phoront together with Gym-
nodinioides on the skin of hermit crab ; it grows in the exo-
skeleton and behaves like Gymnodinioides (Fig. 8). But
there is no encystment of the growii-up trophont, which

22 MORPHOGENESIS IN CILIATES

divides when motile and produces numerous long chains of
tomonts.

The tomont at the last division is shown in Fig. 9a. Be-
tween the ciliary rows, some trichocysts are seen, the origin
of which w^ill be considered later. Between the rows 1 and
9, we recognize the rows x, y, z and an anarchic field of gran-
ules. The latter has been generated by the multiplication
of granules of the row a, and will be organized in three rows
during the early stage of the formation of tomite. The rows
h and c will migrate towards the anterior end and eventually
degenerate. The granules of a will multiply again and
form one of the thigmotactic fields.

During all this period, the ciliate is motile ; cilia are to be
seen everywhere except on the rows a, h, c.

It thus appears that, whereas the majority of kinetosomes
all over the ciliate produce cilia, the kinetosomes of certain
regions are devoid of their characteristic production: cilia.
The problems raised by this situation will be discussed in
the next chapter.

Later on, the granules of h and c disappear; the granules
of a produce persistent cilia. Here again, it is obvious that
the fate of the granules depends on the properties of the
underlying cytoplasm. This conclusion is reinforced by the
consideration of some abnormal cases in which the granules
of h and c also produce cilia.

The mature tomite also shows this beautiful production
of trichocysts. It is again perfectly clear that the trichocyst
arises from a granule which has been formed by division
of a kinetosome. During the growth of the trichocyst, the
granule takes the form of a ring, as centrosomes often do,
e.g., in spermiogenesis. The ring seems to become a part of
the trichocyst itself. The granule having produced a tricho-
cyst seems unable to produce new granules, that is to say,
to divide.

But in Polyspira, the production of trichocysts is not lim-
ited to the tomite. It starts before the first division. At

HOW T0:MITE IMANUFACTURES TRICHOCYSTS 23

A

.^/.:-^

\ i ■/ :

tt:g ?

9l| ;f 8 . 7 :

/?2

'S iff -^ /

Fig. 9. Polyspira delagei. (a) Last division, (b), (c), (d) Tomito-

genesis. Formation of the ogival field {ch.og.) from a. Disappearance

of h and c. c.j., "falciform," thigmotactic, field.

24 MORPHOGENESIS IN CILIATES

this phase, the production of trichocystosomes proceeds in
exactly the same way as in the tomite.

The production of trichocysts continues until the second
division. During the divisions, the kinetosome produces
two trichocystosomes. Only the distal one produces tricho-
cysts. It seems that also some trichocystosomes may be
detached, are able to migrate, and are the origin of the
trichocysts which are scattered all over the surface.

Here again, it is clear that the differentiation of kineto-
somes into trichocystosomes depends on the phase of the
life cycle and presumably on the properties of the cyto-
plasm.

Foettingeria will provide another and more remarkable
example of differentiation. The tomite produces trichocysts
like other tomites. After liberation from the palintomic
cyst, the tomite encysts on a non-specific crustacean. When
the host is ingested by a coelenterate, the cycle will be com-
pleted, but the trophont, unlike the others, will not only
accumulate food. It will grow. The enlarged macronucleus
finally forms a complicated network. During the first 12
to 14 days, after an experimental infection, nothing re-
markable happens: the kinetosomes remain normal. But
after 2 weeks, these kinetosomes will multiply and produce
trichites. , These differ from trichocysts in that, whereas
trichocysts are tubular structures able to be protruded,
trichites are homogeneous organites devoid of this property.

The multiple potencies of the kinetosomes thus express
themselves during the life cycle. The kinetosome is able
to divide and to produce cilia. In the tomite, it produces
a differentiated granule, the trichocystosome, which gives
rise to a trichocyst. In the 2-week-old trophont it produces
differentiated granules, the trichitosomes, which multiply
and produce trichites. The fate of the granule is controlled
not only by its position, but also by the phase of the life
cycle.

HOW TOMITE MANUFACTURES TRICHOCYSTS 25

•

~-«»

^

; •

-* •

^ •

>>\'

p •■ • "

■ •

» »

,>^v

.»,*

» •

,♦ ,•

•* •

1

\

'•"'-.'•

*• i»

«»

'/•'. 1 '

«» «•

■*•

b

««

'. \ A\

AVn^W

V V

Fig. 10. Foettingeria actiniarum. (a) Tomite, showing the small
trichocysts of the kinety 1 and the large trichocysts of the falciform
fields 8 and 9. (b) Young trophont (less than 14 days) ; no trichocysts
or trichites. (c) Old trophont (more than 16 days), showing the

trichitosomes.

26 MORPHOGENESIS IN CILIATES

May I quote here an opinion of Sewall Wright (1941),
discussing some problems of differentiation: ^The stability
of the changed state certainly becomes easier to understand
if it is postulated that there are self-duplicating materials
within the cell which can become modified chemically and
multiply as of the new sort."

The self-duplicating kinetosomes, able to give rise to
self-duplicating trichitosomes, would illustrate this con-
clusion very nicely.

CHAPTER 4

Aspects of the Kinetosome

One kinetosome is always generated by division of an-
other. We see kinetosomes dividing and have no evidence
whatsoever of their formation de novo. They are endowed
with genetic continuity. It is the custom to refer to such
particles as "self-reproducing" or ''autocatalytic" units.
These terms should not be understood as implying that the
particles are independent. A self-reproducing granule is by
no means a self-sufficient granule. When we refer to kine-
tosomes as self-reproducing units, this means only that the
kinetosome never arises de novo, and that some specific
structure or template, present in the kinetosome, is neces-
sary to organize other molecules into a new kinetosome:
like genes, they can only be generated by, or in the presence
of, an equivalent structure

The maintenance of these kinetosomes depends on local
conditions. This is clear when we consider the rows x, y, z.
These rows, bipolar in the tomont, are reduced in the
trophont to short segments with a small number of kineto-
somes. One can interpret this in two ways: either the pos-
tulated specific substance necessary for the maintenance of
the kinetosome is present in limited amounts and disappears
in certain regions of the ciliate; or, in these region a new
substance, or enzyme, is formed, which dissolves or lyses
the kinetosomes. The choice between these two possibilities
is difficult.

Let us remember here one of tne propositions of Paul

Weiss (1947) concerning molecular ecology: "Survival and

27

28 MORPHOGENESIS IN CILIATES

orderly function of the total population are predicated on
the presence of all essential members in definite concentra-
tions, combinations, and distributions."

It is clear also that kinetosomes need some food not only
to live but also to grow and to multiply, and probably some
specific food. It has been noted that, at certain phases of
the life cycle, kinetosomes of one region multiply whereas
others do not. The specific food must therefore be con-
centrated in certain areas. We may quote here another of
Weiss's conclusions: "If the specific existential and opera-
tional prerequisites for the various molecular species and
groups differ at different sites of the cell, different species
will automatically become segregated into their appropriate
ecological environments. As a result, even a wholly in-
discriminate mixture can become sorted out into a definite
space pattern."

It seems plausible to admit that localization of specific
molecules is controlled by their affinities for some differenti-
ated parts of the cortex or, in the last analysis, by the
properties of the given molecule and of the cortex. The hy-
pothesis cannot of course be excluded that these specific
substances are formed only in some areas owing to the dis-
tribution of some specific enzymes.

The granules of anarchic fields may become oriented in
longitudinal rows. They are evidently submitted to some
mysterious and powerful field of forces.

Proposition 6 of Paul Weiss (1947) fits very well with
this hypothesis: "Organization in space of the content of
the cell, and of any of its constituent particulate elements
as well, therefore, presupposes a primordial system of spa-
tially organized ^conditions' to set the frame for the later
differential settlement of different members of the dispersed
molecular populations."

When we look upon the whole series of changes which
take place throughout the life cycle between the rows 7 and

ASPECTS OF THE KINETOSO:\IE 29

1, we are prepared to admit A. L. Cohen's conclusion (1942)
regarding the organization of protoplasm: ''We must realize
that a surface on the microscale is not a mathematical plane,
but a layer of more or less oriented molecules or atoms
with fields of forces which in some instances may be quite
powerful."

Now it is obvious that, in Gymnodinioides, there are vari-
ations of properties from the anterior to the posterior pole,
and from one meridian to another. The notion of morpho-
genetic field takes its full value and expresses itself in a
spectacular way. Sinnott's (1939) definition of the mor-
phogenetic field is here adequate because it is very general :
"A field is the sum of the reactions which an entire proto-
plasmic system makes with its external and internal en-
vironment, reactions which are determined by the specific
physiological activities of the living material of which the
organism is composed."

It is obvious that the life history of kinetosomes is de-
termined by specific changes of the environment. And this
is true not only if we consider the maintenance and mul-
tiplication of kinetosomes, but also their specific metabo-
lism.

The main and most characteristic product of the metabo-
lism of kinetosomes is the cilium. Generally, all the kineto-
somes of a ciliate are cilia-bearing kinetosomes. But many
ciliates, either holotrichous ciliates like the Sphenophryidae,
Sphenophrya, Pelecyophrya, or Gargarius, or suctorians,
are devoid of cilia. Cilia appear only in the ''embryo."
This question will be examined later on. All that is neces-
sary to know at this point is that the embryo loses its cilia,
but that the kinetosomes persist. It is therefore obvious
from these examples that the maintenance of a cilium, like
its synthesis by the kinetosome, is controlled by the en-
vironment.

In Gyvinodinioides, the kinetosomes of the fields a, h, c,
while actively dividing, are devoid of cilia. This absence

30 MORPHOGENESIS IN CILIATES

could be a question of environment. But there is of course
a possibility that for kinetosomes, as for cells of higher or-
ganisms, there is an antagonism between multiplication and
other specific activities, that is to say, an antagonism be-
tween the synthesis of ^'kinetosomal substance" and syn-
thesis of ciliary substance. It is nevertheless possible to
consider as certain that formation of cilia depends on the
presence of one or more specific substance or substances,
and also that environment controls the maintenance of
cilia as it controls their formation.

It has been shown that, at the end of tomitogenesis, all
the cilia-bearing kinetosomes divide, and the daughter
granule produces a trichocyst. Kinetosomes may thus di-
vide unequally: one of the granules remaining a kineto-
some, the other producing a trichocyst or a trichite. It
seems that the trichocystosome itself becomes a part of the
trichocyst. Nevertheless, once a trichocystosome has ex-
pressed its prospective potencies, that is to say, the forma-
tion of a trichocyst, it is no longer endowed with self -repro-
ducibility.

But before forming a specific product, the modified gran-
ule, the trichocystosome of the predivision phase of Poly-
spira, or the trichitosome of the trophont of Foettingeria,
may undergo one or more divisions. The trichocystosome
or the trichitosome is therefore, in some cases, able to live
and to multiply as such.

Sewall Wright (1941), discussing some aspects of the
physiology of the gene, has reached the following conclu-
sion: ^'Differences in local conditions may bring about a
differential accumulation of metabolism products arising by
the interaction of cytoplasm, nuclear products, and the en-
vironment, and eventually bring about the elaboration of
new plasmagenes in the cytoplasm of some regions of the
organism. ... It may be concluded that while the proteins
of cytoplasm are probably autonomous with respect to basic

ASPECTS OF THE KINETOSOME 31

structure, metabolic processes are dependent on active
substances, probably of relatively low molecular weight,
emanating from the nucleus."

Is it possible to apply this conception to the kinetosome?

If we consider one ciliate at a given phase of its cyc'le, we
see that the formation of all the trichocystosomes from
kinetosomes takes place simultaneously. This change is
therefore not the result of a random modification, but the
result of the interaction of the kinetosome with some spe-
cific substance.

It is nevertheless a complicated process involving:

a. The production by the kinetosome of a modified
granule.

b. The production of a trichocyst or a trichite.

As, in the tomite, all the daughter kinetosomes produce
trichocysts at once, two hypotheses must be considered:

1. All the kinetosomes have undergone a normal equa-
tional division. But the environment being changed, the
interaction of the daughter kinetosome with these "con-
ditions" results in the formation of a trichocyst instead of
a cilium. This w^ould mean an induced modification of the
specific activity of the granule. The data concerning
adaptive enzymes, which have been so pertinently and care-
fully reviewed by J. Monod (1947), allow the hypothesis
that one substance could inhibit some enzymes, thus modi-
fying the nature of the end product of the activity of the
kinetosome. It is possible also to consider the hypothesis
that kinetosomes possess many enzymes and that, owing to
the availability of diverse substrates, one or the other of
these enzymes is able to function.

2. The kinetosome has undergone an unequational divi-
sion. As all the daughter kinetosomes produce trichocysto-
somes, this cannot be the result of a random modification.
It can only be the result of the interaction of the mother
kinetosome with some specific substances, that is to say,
an induced modification.

32 MORPHOGENESIS IN CILIATES

During the trophic phase of Polyspira, trichocystosomes
are formed and produce trichocysts whereas "normal" kine-
tosomes continue to produce cilia. Of course, there are
considerable differences between a normal kinetosome and
a trichocystosome. The first is close to the kinetodesma
and, so far as we know, connected to it by a fiber. The
second is far away (relatively) from the kinetodesma and
not directly connected with it. It is therefore possible
either (a) that the substance controlling the production of
cilia is located near the kinetodesma; or (b) that the at-
tachment to the kinetodesma is responsible for some orien-
tation of an unknown material and controls the formation
of cilia. The choice is difficult between alternatives a and
b. It is also difficult between hypotheses 1 and 2.

But the one conclusion remains: the metabolism of the
kinetosome and of its daughter particles is controlled by the
environment. Thus one ''plasmagene'^ may possess many
prospective potencies and turn out different organelles ac-
cording to its position and to the phase of the life cycle.

The study of apostomatous ciliates has thus led to the
morphological demonstration of self-reproducing cytoplas-
mic units. We are able to conclude not only that specific
cytoplasmic particles should exist, but also that they do
exist.

The study of their behavior during the life cycle of the
ciliates furnishes an illustration of the conceptions schema-
tized by Weiss under the name ''molecular ecology/' which
thus receives the support of visible allies.

The question of the equivalence of all kinetosomes will
be discussed in Chapter 6. Let us admit, for the time being,
that all kinetosomes are essentially equivalent, but are or-
ganized in different systems and structures, according to
their position in the ciliate and the phase of the life cycle.
And as these differences are observed in a single ciliate, the
hypothesis of a change in the genome being responsible for

ASPECTS OF THE KINETOSOME 33

these phenomena is excluded. The fates of the kinetosomes
are largely phenotypical expressions of changes in the prop-
erties of their environment.

Thus kinetosomes illustrate in a most spectacular way
the notion of morphogenetic field and of organizers. From
the study of the life cycle of ciliates, it may be concluded
that kinetosomes as a whole play a fundamental role in
their morphogenesis.

But ciliates are non-cellular organisms. Are kinetosomes
of any use in understanding the problem of morphogenesis
in "higher organisms"? It is possible to consider that cells
which do not produce cilia are unable to produce the spe-
cific substance which enables the formation of cilia. But
it is easy also to visualize kinetosomes being segregated, so
that cells which possess kinetosomes will develop cilia,
whereas cells devoid of kinetosomes will not.

It is possible furthermore to consider that, if a kineto-
some is changed into a trichocystosome, the potentiality of
the host-cell will be changed: it will produce trichocysts
instead of producing cilia.

Thus, the kinetosome provides a model for one possible
mechanism of cell differentiation in higher animals.

A multicellular organism has differentiated cells. A cili-
ate has differentiated parts. It seems therefore important
to point out that self-reproducing particles may behave in
different ways in different parts of a ciliate, just as viruses
behave in different ways in different cells of an organism.

C. Darlington (1939) considers the plasmagenes as "a
relic of the naked gene of a remote prechromosomian period,
a relic which has been preserved in spite of its being a nui-
sance in heredity because it is a necessary cog in the ma-
chinery of development." Kinetosomes considered as plas-
magenes or as visible specific cytoplasmic units endowed
with genetic continuity are perhaps a nuisance. But, in
providing a useful model for concepts concerning specific

34 MORPHOGENESIS IN CILIATES

cytoplasmic units which we are compelled to postulate,
they are a helpful nuisance.

It is extremely difficult to understand how, during the
development of an organism, cells with an apparently con-
stant genome may become differentiated. The concept of
the unequal distribution of specific units, or self-reproduc-
ing plasmagenes, has been built up to explain cell differen-
tiation, and the concept of molecular ecology in order to
explain cell and tissue organization. But we have no mor-
phological or physiological data which would constitute a
proof of the existence of any one of these postulated units.
Also, it is really strange that biologists, faced with this
problem, should have ignored or even denied the possible
existence of cytoplasmic, visible, self-reproducing units.

Chatton and I, when working out the life cycle of apos-
tomatous ciliates in the years 1923-1932, did not realize
completely the possible importance of the kinetosomes for
some of the future problems of developmental physiology
and of molecular ecology.

The study of apostomes shows that different morphologi-
cal types, different structures or patterns, organelles of dif-
ferent physiological function may be formed from the very
same material, the kinetosome. The condition for these
changes is a heterogeneous cortex. The movements of the
kinetosomes are controlled by the metabolism.

A gene mutation modifying the enzymatic system would
be able to produce hereditary morphological changes. But
it must not be forgotten that kinetosomes represent a popu-
lation of "self-reproducing" units. These units, like any
other, must be able to undergo changes. If a change is
favorable, the "mutated" kinetosome may replace the oth-
ers. In many ciliates, kineties reproduce themselves by
elongation; they are endowed with genetic continuity. It
is therefore possible that different mutants of kineto-
somes are selected in different meridians. Nevertheless,
movements of kinetosomes are controlled by the metabo-

ASPECTS OF THE KINETOSOME 35

lism. Metabolism is controlled by enzymes which are con-
trolled by genes. Enzymatic activity is controlled by the
presence of specific substrate. It thus appears that certain
specific activities of an organism are under the triple control
of genes, of self-reproducing cytoplasmic particles, and of
the environment.

CHAPTER D

Division, Absence of Division,
Induced Division, and Morphogenesis

When considering the Hfe cycles of apostomatous ciliates,
one would be tempted to conclude that the arrangement of
kinetosomes as it is seen in the structure of the tomite is
the indirect consequence, or the necessary corollary, of
modifications connected with, or controlled by, division.
This hypothesis must now be considered in the light of
some aberrant life cycles.

In any one of the species we have examined, it may
happen that the trophont takes up only a small amount of
food. These undernourished trophonts encyst. They do
not divide. However, they undergo metamorphosis and
give rise to a tomite. This tomite will encyst on its host.

Thus the complete series of metamorphosis, the move-
ments of kinetodesma and kinetosomes, take place without
division. They are obviously and necessarily the conse-
quence of changes in the properties of the cytoplasm, which
can only be the reflection of the metabolism as controlled
by the interaction of hereditary outfit and external factors,
including food.

The study of Phoretophrya will allow discussion of this
obvious conclusion. The grown-up trophonts which escape
the exoskeleton of Nebalia encyst and undergo detorsion.
They may evolve in two different ways. They may follow
the normal route: division, formation of a tomite, encyst-
ment. The phoront will escape at the molt. But a certain
number of encysted ciliates, for some unknown reason, do
not undergo division. They are transformed into one huge

36

DIVISION AND :\rORPIIOGENESIS

37

tomite. This tomite will escape the cyst, and after a short
free life forms a new cyst on a Nebalia. This large phoront
has lost the power to divide without an external stimulus.
Division will start only some hours before the ecdysis of
the host. It is apparently induced by some substance which

Phoront

Apotomite

Grown-up 5
trophont

X

Apotomont

Fig. 11. Apotomy. The food intake by the trophont has been small.
The cycle is completed without any division. Apotomy may occur

in many species.

is excreted by the host at this period. Nevertheless, this
induced division proceeds normally as in other species.
However, after the last division, it is not the tomital struc-
ture which is produced, but the structure of the trophic
phase.

When division takes place normally, the ciliate is or-
ganized into the tomital structure. When division takes
place after a resting period and is induced by the ecdysis of
the host, the ciliates have the structure of the trophont.

The situation is somewhat the same in Synophrya hyper-
trophica. The life cycle is represented on the diagram.

38 MORPHOGENESIS IN CILIATES

Just as those of Gymnodinioides, trophonts of Sijnophrya
take up food in the discarded exoskeleton. They abandon
the molt, encyst, and divide, and tomites are differentiated
which encyst on the integument of the crabs. But the

Discarded

Nebalia

Nebalia

Typical Cycle

Atypical Cycle

Fig 12 I'horetophrva nebdiae: life cycle. Normal cycle on the left.
On the right, formation of the huge apotomite which will encyst on
a Nebalia and in which division is induced by the pre-ecdysic phe-
nomena. The phoretotomite has a trophontal structure.

DIVISION AND MORPHOGENESIS

39

phoront, instead of awaiting" ecdysis, iiiooiilates itself in the
crab. Leucocytes will form a harriei* and isolate the para-
site in a limited sector in which th(> ciliate feeds. The size

Empty phoretic cyst

Young trophont
V (blood form)
or hypertrophont

Grown-up sanguicolous hypertrophont or hvpertomont

Mature

.'\u\ icolous

trophont

Hypertomite
or young

exuvicolous
trophont

^^^

Fig. 13. Synophrya hypertrophica : life cycle. The division of the
internal hypertrophont is induced by ecdysis. The hyperpalintomy

yields trophonts.

increases enormously. The macronucleus is altered into a
complicated netw^ork. The grown-up ^^hypertrophont" will
now wait for ecdysis. The sexual behavior of the male
crab allows us to see what happens before ecdysis takes
place. It is known that copulation of crabs takes place only
immediately after ecdysis of the female, between a hard
male and a soft female. In order to copulate, the male

40

MORPHOGENESIS IN CILIATES

has to select a female before ecdysis. A delicate pinching of
the female limbs apparently enables him to recognize a
change of consistency of the tissues 24 to 48 hours before
the molt. He then climbs on the back of the female and

Fig. 14. Synoplirya hijpertrophica. Last division of the hypertomont
and morphogenesis of the hypertomite with a trophontal structure.

waits. If such a male-carrying female is sacrificed, one finds
that all the hypertrophonts are undergoing palintomy.
Division is induced by some changes which take place 48
to 24 hours before ecdysis. However, this hyperpalintomy
yields hundreds or thousands of ciliates with the typical
structure of the trophont. They will escape after ecdysis,
enter the molted exoskeleton, and behave as normal tro-
phonts. Here, as in Phoretophrya, the ciliates formed after

DIVISION AND MORPHOGENESIS 41

the ecdysis-induced palintomy are of the trophontal type.
Thus, Synophrya enjoys two palintomic phases: one takes
place after growth in the molted exoskeleton and yields cili-
ates of the tomital structure. The other takes place after
growth in the blood of the crab and a long resting phase
and yields ciliates of the trophontal type. As far as visible
superficial structures are concerned, palintomy and hyper-
palintomy are identical. The difference lies in the post-
palintomic phase. Obviously the phenomena which follow
the last division are controlled by some metabolic process
which is itself controlled by the metabolism of the trophont.

CHAPTER U

Genetic Continuity of Kineties

and the Problems of Isolated Populations

of Kinetosomes

The complicated series of events we have described poses
two important problems: (1) Why do kinetosomes some-
times behave differently in different sectors of one kinety?
(2) Why do different ciliary rows behave differently?

Let us consider first the rows 8 and 9. Their posterior
part is simple like the other rows. The median part has
disappeared, kinetodesma as well as kinetosomes. The
kinetosomes of the anterior part have divided, once in the
row 8 and twice in the row 9 (see Fig. 3b, p. 13).

It is perhaps necessary to point out that all kinetosomes
of one kinety are equivalent. During division, the median
kinetosomes become located either on the posterior part of
the '^proter" or on the anterior part of the ^'opisthe"; the
proter is the anterior daughter ciliate, the opisthe the pos-
terior one. It is therefore obvious that the fate of the
kinetosomes of one kinety depends on its position on the
ciliate. This means that the behavior of the kinetosomes,
the facts that they remain without apparent change, that
they disappear, that they multiply, depend on the prop-
erties of the underlying cytoplasm. The cytoplasm may
be "neutral." It may produce the disappearance of the
kinetosome or induce its multiplication. Properties of the
cytoplasm vary in the anterior, median, and posterior parts

of the kinety in the most conspicuous way.

42

GENETIC CONTINUITY OF KINETIES 43

If wc consider the rows x, y, z, we reach the same conclu-
sions. The conditions for thcii- maintenance are reaUzed
only in the median part of the tomite.

The fact that the anterior sector of the kinety x will form
the rosette or mouth organ seems to show that some special
morphogenetical field is always located in the corresponding
region. Nevertheless, the hypothesis cannot be excluded
a priori that the kinetosomes and fibers of the row x possess
some special properties which are responsible for their re-
sponse. According to this hypothesis, the formation of the
rosette would be not the effect of a localized morphogeneti-
cal field, but the reflection of the properties of a specialized
kinety to conditions present everywhere. But it is difficult
to understand, if this hypothesis is admitted, why it is not
the kinety a: as a whole which is turned into a rosette.

Nevertheless, this brings up the problem of the different
behavior of different kineties. A somatic ciliary row of
Gyinnodinioides and of other apostomes is endowed with
genetic continuity. A given somatic kinety of the proter
and of the opisthe is the anterior or the posterior part of the
parent's kinety. This is the type called "direct continuity
by elongation" by E. Chatton and A. Lwoff. The reproduc-
tion of X, y, z is of the same type, with the difference that
they are bipolar only before division, whereas in the resting
phase they are reduced to a short segment of five to twenty
kinetosomes, according to species.

In Pericaryon cesticola y and z have only two kineto-
somes and X only one. What happens when the regression
reaches its limit, that is to say, when a ciliary row present
during one phase disappears during the following phase?
How is it regenerated? In Polyspira and Gymnodinioides,
the rows h and c disappear during the tomital and phoretic
phase and are absent in the trophont. Before and during
palintomy, the kinetosomes of a divide and form an anarchic
field, the kinetosomes of which are later oriented in two
lines h and c.

44

MORPHOGENESIS IN CILIATES

In Foettingeria, a, h, and c are formed anew from the
kinetosomes produced by the kinety 1. In Chromidina ele-
gans the whole ''oral" system a, b, c, x, y, z is absent in the
trophont. It is formed during palintomy from the kineto-

FiG. 15. Pericaryon cesticola. Kineties y and z are reduced to two
kinetosomes; kinety x to one kinetosome.

somes derived from 1. This is a unique example among the
ciliates of the formation de novo during one phase — tomite
— of the oral ciliature absent during another phase — tro-
phont. Some sort of regulation therefore exists.

These kinetosomes originating from one kinety behave
differently from the mother kinetosomes which have re-
mained in line in the mother kinety. Once again, we reach

GENETIC CONTIXriTY OF KIXETIES 45

the conclusion tliat the fate of kinetosomes is controlled
by the underlying cytoplasm. Hut this conclusion is not a
contradiction of the fact that some kinetics are endowed

* ,

* .

// ;

*■ ^ .

* ,♦ «

■' .> ^ «' .' ■

/ * f. • ^

■' •> i ^ . ■

. * « ^* "t

,'.

^

»•• *. ^ .• ■

e

ft

* •• ^ i «, ■ •

^^ '•

%

.'

•' *> ^ . . '

<M» ■?..'•'•

,

*

c

•

. . ♦'^ . ■• .« •

r ^ ; .' ; : .

,

■ • .•''•' ^ * r

(•.,., • • /

.

.*

«.'',' ^.

^» • , «

• *'.•.. • ' *■

. / r . .' <*• «.

... .'...• i

. •

1 . ' ' '^

• • r ;•;;;• .:^ 4>

*

■' ^

.• • .. r~^r^ *'^

,

,. •

• ' • .? " ri , • V

* i" • ;• •>

.

* 1*

/.' ■^ .' ,' »

.\ .->

4->

•^ r* /

!*

•

' , .; ».

- " ' t ' "* *

•

•*

■ . . " .\

* * * •

-*

• * ■« *

•

'" " ' ■■ .■ *

V • • ',

* « •' '. •

'xX/, ^ ■

t * * .'

Fig. 16. Chromidina elegans: protomites. Formation of the oral cilia-

ture by division of the kinctosome of kinety 1. The oral ciliature is

totally absent in the trophont and in the tomont.

with genetical continuity by elongation. This means that
more or less autonomous, self-perpetuating populations of
kinetosomes formed by spontaneous mutations may be seg-
regated in different meridians of the organism. And as con-

46 MORPHOGENESIS IN CILIATES

ditions may be different in different meridians, there is a
possibility that selection of mutated kinetosomes may take
place. Thus the possibility that different lines of kineto-
somes could be different cannot be excluded. A change in
the morphology of a ciliate could be the result of a new re-
sponse of populations of mutated kinetosomes to the same
environment.

The work of T. Sonneborn and G. Beale (1949) has shown
that under the influence of antisera the antigenic type of
Paramecium is changed. An analysis of this phenomenon
has brought the authors to the conclusion that the antigenic
type was controlled by plasmagenes. Taking into account
the paralyzing effect of antisera, I have been led (1949a)
to the hypothesis that Sonneborn and Beale's antisera could
act on cilia. The responsible antigens would be ciliary anti-
gens. As cilia are produced by kinetosomes, these could
have a share of responsibility in the Sonneborn-Beale phe-
nomenon. The hypothesis according to which antiserum
could orientate the selection of kinetosomes or modify their
structure seems plausible. It is possible also that a sub-
stance analogous to the ciliary antigen could exist in the
kinetosome. Nevertheless, the problem of relations be-
tween the ciliary material and the kinetosome's constitu-
ents endowed with genetical continuity is posed by Sonne-
born and Beale's highly interesting experiments. This
problem of the natural or experimental selection of kineto-
somes remains one of the main problems of ciliate biology.

According to V. Tartar (1941), "the ciliates present us
with a living fiber system having morphogenetic capacities."
Are we really entitled to speak of "living fibers"? Or to
consider that the visible cortical structure commands mor-
phogenesis?

Tartar has cut Paramecium in such a way that the an-
terior part contained two nuclei but was devoid of oral
structure. These pieces never regenerated the mouth; "a
further evidence," writes Tartar, "of this rigid differentia-

GENETIC CONTINUITY OF KINETIES 47

tion" in Paramecium. This may be true and could mean
that some speciahzcd kineties or kinetosomes are endowed
with genetical continuity. This is plausible. We know
that in the ciliate Glaucoma scintillans or Leucophrys piri-
jormis (= Glaucoma piriformis = Tetrahyviena gelei) the
mouth is always produced by one kinety: the stomatogenic
kinety or kinety 1 [E. Chatton, A. and M. Lwoff, J. Monod
(1931)]. However, we do not know whether the property
of the kinety 1 is related to the special properties of its
kinetosomes or to the localization in its vicinity of specific
^'molecular species." Probably this asymmetry reflects the
anisotropy of the cortex which is responsible for the action
of these "molecular species" which we consider responsible
for the reproduction of some localized kinetosomes and their
organization into a specific pattern. But a mouthless Para-
mecium is unable to feed, and the hypothesis cannot be ex-
cluded that the absence of mouth formation is the result of
starvation. The inability to regenerate the mouth could
also be due to the removal of localized cytoplasmic or-
ganelles.

The problem of the autonomy and differentiation of
kineties is not yet solved. Perhaps the heterotrichous cili-
ate Licnophora wall provide a good example of its complex-
ity. The ciliary system of Licnophora chattoni comprises
two parts : the oral system and the basal system. According
to the investigations of S. Villeneuve-Brachon (1940), the
peristome of the daughter ciliate originates from one or a
very few kinetosomes escaping from the original peristomial
system of the mother. These kinetosomes multiply, thus
forming an anarchic and homogeneous field of closely
packed kinetosomes. Later on. kinetosomes are aligned and
organized just as if submitted to some orienting forces. The
kineties of the basal disc are reproduced by division (direct
continuity by elongation).

W. Balamuth (1942) has performed some operations on
another closely related species of Licnophora, L. macfar-

48 MORPHOGENESIS IN CILIATES

* *

^ ■». ^ » • ♦ »

• * i

♦ t

.^\

\ »*

^

t i tji^ b ^ c

%

* « T' - s * . T * »

1 . «

h

/ fa * * * » ' *

-,

X~(

'* *••■ .

^■•e
."'«

i

. 4 ■/

. ' V

v->

t

e

^\

t.N

" 1

'^A

Fig. 17. Stomatogenesis in Glaucoma sciiitillaus and Leucophnjs piri-
formis, (a) Glaucoma scintillans. The very beginning of the mouth
formation. Some kinetosomes have been produced at the left of
the stomatogenic kinety 1. (b), (c), (d) Later stages of mouth
formation, (e), (f) Stomatogenesis of Leucophrys pirijormis. (e)
Division of the kinetosomes of the stomatogenic row 1. (f) Mouth

is completed.

GENETIC CONTINUITY OF KINETIES

49

landi. It appears that it is relatively easy for this ciliate to
regenerate its peristomial zone, but it cannot regenerate the
basal disc. This beautiful (experiment unfoi'tunately does

Fig. 18. Licnophora chattoni. (a) Ciliate in vivo, (b) Early stage of

the stomatogenic field. (c), (d) The anarchic field. (e) Alem-

branelles are modelled into the anarchic field, (f)-(i) Division of the

ciliate, showing the reproduction of the basal disc.

not solve the problem. The inability to regenerate the basal
disc with its ciliary system could be due: (a) to the sup-
pression of a specialized line of kinetosomes; (b) to the
suppression of some cortical elements endowed with geneti-
cal continuity; (c) to the suppression of both specialized
kinetosomes and cortical organelles.

50 MORPHOGENESIS IN CILIATES

In apostomatous ciliates, the number of kineties remains
constant throughout the cycle. But owmg to the great dif-
ferences of size, the distance between kineties varies enor-
mously from the tomite to the mature trophont. In other
parasitic ciliates, the phenomena are quite different. Ich-
thyophthirius multifiliis has been studied by H. Mugard
(1947). The mature trophont has approximately 2040
kineties. This trophont encysts, undergoes palintomy, and
gives rise to a great number — approximately 2800 — of
"theronts" or hunting forms. The theront has only 43
kineties. At the equator of the ciliate, the distance between
two kineties is approximately 1 ft in the mature trophont
and 1.5 jji in the theront. Despite considerable changes of
the value of the surface, the distance between two kineties
remains approximately constant.

What is the mechanism of the variation of the number of
kineties? We may start from the theront, the kineties of
which are practically bipolar. During the growth, some
kineties are interrupted; a multiplication of kinetosomes
takes place. Ramifications are produced, and the new
branches find their place between two other kineties. Thus,
new kineties are formed during the increase of the surface
of the cortex. During palintomy, short sectors of kineties
are to be seen on the surface of the tomont. The division
of the ciliate is accompanied not by a division of bipolar
kineties, but by an apportionment of segments of kineties.
The result is, at each generation, a reduction of the number
of kineties. It is only after the last division that the tomite
regularizes its ciliary system, which becomes bipolar. Thus,
in Ichthyophthirius, there is no genetical continuity of kine-
ties, but reorganization of kinetosomal material in longi-
tudinal kineties. And the nature of cortex equilibrium is
such that throughout the cycle, despite considerable varia-
tions of size and owing to a constant change of the number
of kineties, the distance between two kineties remains con-

GENETIC CONTINUITY OF KINETIES 51

stant. Things happen as if the number of kinetosomes per
surface unit were more or less constant.

The constancy of the cortical pattern is not the sole result
of the perpetuation of autonomous populations of kineto-
somes or of specific kinetics. It appears to be the result of
the response of an apparently homogeneous population of
kinetosomes to their environment.

CHAPTER i

Order and Disorder;
Torsion and Detorsion

When considering the different phases of the Ufe cycle
of apostomatous cihates, one is struck by the alternation of
spiral and meridian stages. This is especially striking in
Foettingeria, and thus we are naturally led to the problem
of torsion and asymmetry. Before discussing this problem,
let us say a few words concerning the kinetodesma.

As already stated, the kinety is essentially a line of
kinetosomes with a kinetodesma at their right. The origin
of the kinetodesma is not clear. But in the trophont of
Foettingeria where the kinetodesma is, in some of its parts,
relatively large, it shows a fibrillar structure and the kineto-
somes seem to be in continuity with the fibers, that is to
say, to be attached to the kinetodesma. It is known that
kinetosomes of flagellates often produce fibers. It is there-
fore possible, and probable, that the kinetodesma represents
fibers of kinetosomal origin.

Whatever its origin may be, the kinetodesma seems to
play an important role in morphogenesis. In the trophont
of the apostomatous ciliate Traumatiophtora punctata, an
anarchic field of kinetosomes is always present between the
anterior sectors of the rows 10 and 1. The row 11 starts
somewhat lower. Obviously, the kinetosomes of the an-
archic field represent the kinetosomes of the anterior sector
of the kinety 11. This conclusion is reinforced by the fact
that these kinetosomes are paired, as are always the kineto-
somes of the anterior sectors of the rows n and n — \ (in
this case n = 11).

52

ORDER, DISORDER; TORSION, DETORSION 53

9/ 3

7

• . •

'».^*.-

z

.1

i"'

'

/

^

,^

da

/?l\^

hi^

#

^

'-10 J-

/ •

^ "^ .Si^^«"lS»»«»«*tb

S 2 ^ ' ^ "^

^ * * ' # ,

f

Fig. 19. TraiDnatiophtom punctata: trophont. The kiiietocle.>nia of
the anterior part of kinet}' 11 has disappeared. The kinetosomes of
the anterior part of 11 are scattered in disorder. They exhil)it a doul)le
structure, just as the granule of the anterior part of 10 — remainder
of the tomital "falciform field."

54

MORPHOGENESIS IN CILIATES

In the region where 11 exists as a row, a kinetodesma is
visible. There is no kinetodesma further up. The kineto-
desma has disappeared, and it seems highly probable that
its disappearance is responsible for the scattering of kineto-
somes. The kinetodesma appears as the framework of
kinetosomal order, the visible agent by which the hitherto
unknown "morphogenetic forces" exert their mysterious
orienting action.

Fig. 20. Phoretophrya nebaliae. Formation of the hypertomite, show-
ing the elongation of kineties 1, 2, 3.

During morphogenesis of the trophont of Phoretophrya
nebaliae, some kineties increase in length. Is this purely
a passive phenomenon, corresponding to the stretching,
under cytoplasmic pressure, of a fiber, anchored at its an-
terior and posterior ends? Or is the stretching active, that
is to say, the result of elongation of certain fibers by syn-
thesis of new material? The latter hypothesis seems plaus-
ible. If it is admitted, it is also necessary to admit that the
unequal growth of the different kinetodesmas is the expres-
sion of an unequal distribution of the substances inducing
the growth of kinetodesmal fibers. Nevertheless, the un-
equal development of kinetodesmas, even if it is held re-
sponsible for the torsion, cannot be the cause of asymmetry;
it would rather be an effect of this asymmetry.

Let us consider now a more remarkable example of tor-
sion.

ORDER, DISORDER; TORSION, DETORSION 55

Foetfingcria lives in tlio gastrovasciilai' fluid of cooleii-
terates. The size of the trophont varies from 20 to (UK) /x.
Its structure shows nothing remarkable.

If the trophont, whatever its size may be, is taken out of

.■■qj2?

Fig. 21. Foettingeria actiniarum: trophont.

the Actinia, it encysts and undergoes a detorsion. Very
early, the kinetosomes of the row 1 produce by division a
field of granules w^hich is then oriented in one, and later on
in three, rows. A perfectly bipolar structure is produced.
Division starts and produces some thousands of tomites.
The formation of the tomite is somewhat more complicated
than in the other species. The rows x, y, z are reduced pro-
gressively to the size they will have in the trophont, but at

56

MORPHOGENESIS IN CILIATES

Fig

. 22. Foettingeria actiniarum: detorsion and palintomy.

ORDER, DISORDKr.; TORSION, l)i:roRSU)N 57

Fig. 23. Foettingeria actiniarum: tomitogcnesis. (a) Last division.
(b)-(g) Regression of x. y, z. Formation of the ogival and falciform
fields.'' Torsion, (h)-(i) The tomite. The posterior spiral roil has
been invaginated. (j) The rosette, formed from x' , as seen in the

trophont.

58

MORPHOGENESIS IN CILIATES

the same time the other ciliary rows are rolled up at the
posterior end into a sinistral spiral coil. This spiral coil
then suddenly disappears. It has been invaginated into the
posterior end. This apart, the tomite shows nothing re-
markable. The anterior part of the row x will give rise to

Fig. 24. Foettingeria actiniarum. Growth of the trophont. The de-
torsion accompanying the increase of size is clearly visible. The smallest
trophont (a) is 29 fi long. The largest (c) is 60 /i. Compare with
the 160-Ai-long trophont of Fig. 21.

the rosette or mouth organ which has the same structure
and size in the tomite as in the adult. The spiral coil
formed and invaginated during the tomitogenesis of Foet-
tingeria will be extruded during the phoretic phase. But
the extruded spiral will be dextral, that is to say, have an
inverted direction. Thus it is obvious that torsions of the
cytoplasm may take place independently of elongation of
kinetodesmas.

This is certainly a very rare, if not unique, example of
the succession of a dextral and sinistral structure in one

ORDER, DISORDER; TORSION, DETORSION

59

organism. In the gastropod Limnaea peregrea, the dextral
or sinistral torsion is controlled by a pair of allelomorphic
genes. In Focttingcria dextral and sinistral torsions do not

Fig. 25. Foettingeria actiniarum: different aspects of the ciliary ?;ys-
tem. (a) Median protomont. (b) Last division, (c) Torsion of the
protomite. (d) Protomite. (e) Posterior pole of the protomite. (f)
Tomite. (g) Encysted phoront. The invaginated spiral coil has been
devaginated. (h) Young trophont. The torsion in the phoront (g) and
trophont (h) are inverse of the protomital torsion (e).

reflect different genomes, but are the response to definite
phases of the life cycle.

During the trophic phase, changes of the superficial archi-
tecture consist essentially in the unrolling of the kineto-

60 MORPHOGENESIS IN CILIATES

desmas. Before division, the enrolled ciliature of the tro-
phont becomes meridian, which means an important
shortening.

It is possible to describe the morphology of ciliates in
terms of kinetosomes and their derivatives. The morpho-
genesis of a ciliate is essentially the multiplication, distribu-
tion, and organization of populations of kinetosomes and of
the organelles which are the result of their activity. Kineto-
somal order is controlled, at least partially, by the kineto-
desmas. Embryologists have been led to postulate the ex-
istence of specific patterns of protein molecules or fibers
which would appear during embryonic development and
play an important role in morphogenesis. F. 0. Schmitt
(1941) has in vain tried to obtain evidence for this type of
structure. The study of apostomatous Protozoa shows that
such fibers do exist and that they play, at least in ciliates,
an effective role in morphogenetic processes.

As these fibers undergo unequal growth during develop-
ment, we have to predicate an asymmetrical distribution of
the substances controlling the synthesis of the fibrous mate-
rial. But, evidently, the problem of asymmetry has been
only pushed back, and we have studied the results of asym-
metry rather than its cause.

Finally, we have to recall once more that kinetodesmas
are asymmetrical fibers. The problem of the origin of this
asymmetry still awaits its solution, just like the problem of
the spiral structure of cellulose fibers or of starch molecules.

CHAPTER O

Problems of Equilibrium

If dividing Leucophrys piriformis are treated with a
hypertonic solution [E. Chatton (1921)], the constriction is
inhibited. The proter and the opisthe may fuse in such a
way that the tw^o stomatogenic meridians are back to back.
The monster has a double set of somatic kineties, two
mouths, one macronucleus, and one or two micronuclei.
According to E. Faure-Fremiet (1948a), the stability of the
^^doublet" of Leucophrys patula is bound to the mainte-
nance of axial symmetry. If any asymmetric phenomena
occur during division, if for example one mouth is lost, the
result will be a ciliate possessing one mouth and two sets
of kineties. Then, progressively, the number of kineties
will diminish and go back to the original number. The
nuclear duality, when it exists, disappears, and finally the
normal, original structure is obtained.

But it happens sometimes that non-disjunction of the
proter and opisthe leads to heteropolar monsters, which are
able to feed and to grow, but not to divide, and which
finally cytolyse. In these heteropolar monsters, the kineties
diverge from two or more poles and their elongation gives
rise to multipolar systems. According to Faure-Fremiet,
there is a "geometrical impossibility" of the formation of a
division zone separating two systems of homogeneous and
homopolar kineties. It must not be forgotten that kineties,
according to the law of desmodexy, are dissymmetric struc-
tures. The kinetial system is compared by Faure-Fremiet
to a "crystalline network" or to the ''complex mesh of a
supermolecular structure of the crystalhne type." Faure-

61

62 MORPHOGENESIS IN CILIATES

Fremiet (19486) considers that ''it is the cihary system,
or, more precisely, the infracihature in the sense of Chatton
and Lwoff, which commands all the regenerative morpho-
genesis." Let us recall that the infraciliature is the sum of
kinetosomes.

The study of morphogenesis, in very evolved ciliates, e.g.,
Licnophora and Euplotes, will show later how, starting from
kinetosomes and other non-visible materials, a specific com-
plicated structure may be formed. Kinetosomes are the in-
struments of morphogenesis. The importance of the in^
fraciliature is therefore not questionable. However, I
should like to point out that, if kinetosomes are necessary
for morphogenesis, they seem not to ''command" but to
obey some mysterious force which is responsible for their
orientation. Perhaps it is better to say that they cooperate
with some other factors, or that morphogenesis is the result
of the interaction of kinetosomes with other factors. This
problem will be discussed later on.

Coming back to the problem of symmetry and equilib-
rium, I should like to add a few remarks to Faure-Fremiet's
important experiments and discussion. The cortical pattern
and especially the kinetial system are certainly important.
When considering many evolved ciliates and especially the
group of Thigmotricha, it is clear that the division "zone"
does not coincide with the theoretical equator of the organ-
ism, but "cuts" the kineties in their middle, even if they are
located on the anterior half of the parent [E. Chatton and
A. Lwoff (1949)]. The question naturally arises, and this
is not a purely academic discussion, whether it is not the
middle of the kinety which determines the position of the
constriction zone. This would mean a more or less "autono-
mous" equilibrium of the kinety. But studies of apostomes
have shown that the length of the kinety is controlled by
its environment, that is to say, by properties of the cortex
as a reflection of the metabolism.

PROBLEMS OF EQUILIBRIU:\I 63

Therefore, the fact that kiiu>ties are cut in two eciual parts
would mean that the niicklle of the kinety corresponds to
the middle of the underlying "morphogenetic field."

The division of a ciliate into two equal parts is the most

Fig. 26. Plagiospira crmita. (a) Dorsal view, showing the short thig-

motactic kineties. (1)) Division. The thigmotactic kinetics are cut in

their middle by the oblique striction zone. A and B, preoral kineties.

common and certainly the primitive condition. But some
ciliates produce a bud, that is to say, a small opisthe. This
happens in many parasitic ciliates or in suctorians w^hich
feed for long periods on other ciliates and are, if considered
from a nutritional point of view, '^biochemical parasites"
[see A. Lwoff (1944)].

64 MORPHOGENESIS IN CILIATES

When in such parasites kineties are present and bipolar,
they are cut not in their middle, but far behind the equator
of the animal. In Chromidina elegans, for example, which
is attached to the epithelium of the kidney of Sepia elegans
by its anterior pole, the first constriction zone separates a
fragment one-tenth of the length of the animal. If we con-
sider the form of the ciliate with its enlarged anterior ex-
tremity, the volume of this fragment is far less than one-
thousandth of the volume of the parent. The detached pos-
terior part will undergo four to five divisions. At each divi-
sion, the constriction zone lies behind the equator.

The combination of fixation and of some nutritional fac-
tors has resulted in the shifting towards the posterior end of
the normally equatorial constriction zone. We could ex-
press this in terms of an inhibition "gradient." However,
considering the fact that all segments are unequal, one is
tempted to ascribe this "heterotomy" to a heterogeneous
structure of the cortex with properties varying progressively
from the anterior to the posterior pole. The constantly
flowing endoplasm of the ciliate cannot be considered re-
sponsible for this phenomenon. The fact that trichocysts
are formed only in the vicinity of the posterior end shows
that the "morphogenetic substance" responsible for tricho-
cyst formation is localized, whether formed or adsorbed we
do not know, in the region where division will take place.
This can be understood only if we admit that the cortexes of
the anterior and posterior parts are different.

The fact that heterotomy (or budding) also takes place
in suctorians where no kinetodesmas have been detected
seems to show, if kinetodesmas are really absent, that the
fibers express, rather than control, the properties of the
cortex.

CHAPTER Z^

The Cortical Network of Suctorians;
Reproduction and Organization

Adult suctorians are devoid of cilia. They feed by numer-
ous sucking extensions. The non-ciliated parent produces
a ciliated daughter organism generally referred to as an
embryo or bud.

The origin of the cilia of the embryo in this group of
organisms was, for a very long time, one of the problems of
protozoology. It was solved by the study of Podophrya fixa
[E. Chatton, A. and M. Lwoff, and L. Tellier (1929)]. On
the surface of the adult are numerous kinetosomes which
are scattered all over an irregular network. The first sign
of reproduction is the multiplication of these granules in
one region of the adult. The kinetosomes become aligned
in regular rows, and the hitherto irregular network is now
formed, in this region only, of square units which are also
regularly aligned. Cilia are produced only by the kineto-
somes of this organized field.

It is obvious that the kinetosomes of this region are sub-
mitted to conditions which induce their multiplication and
that some forces, or fibers, must arise which orientate the
network and the kinetosomes.

A closely related species, Podophrija parasitica, has been
examined by E. Faure-Fremiet (1945b). It lives as para-
site on the surface of ciliates and also produces ciliated em-
bryos. However, when the host is exhausted, lines of kineto-
somes are formed, not only on one area, but all around the
suctorian, and cilia are produced. The adult as a whole is
thus transformed into a huge "embryo.'^ The change takes

65

66

MORPHOGENESIS IN CILIATES

Fig. 27. Podophrya fixa. (a) Adult. Beginning of the formation of
the embryonic field, (b) and (c) Organization of the kinetosomes of
the embryonic field and of the meshes of the cortical network.

(d) The embryo.

CORTICAL NETWORK OF SUCTORIANS

67

place independently of any division. It appears therefore
that the arrangement of kinetosonies and the pioduction of
cilia are controlled by the nutrition. W'lien tlie ciliate feeds,

■\V !'/''• '• -/

Fig. 28. Podophrya parasitica, (a) Adult and embryo, (b) Free

embryo, (c) Newly fixed embryo, (d) Embryo resulting from the

total transformation of an adult, (e) "Tokophrya' form.

kinetosomes are organized and produce cilia only in one
region, which becomes the surface of the embryo. When
the nutrition ceases, the adult as a whole is organized and
produces cilia.

68 MORPHOGENESIS IN CILIATES

From the evolutionary point of view, it is worth noticing
that the ciliated phase is phylogenetically the primitive one.
The production of the ^'embryo," characterized by the or-
ganization of the anarchic superficial network into a regular
pattern, the lining up of kinetosomes, and the production
of cilia, corresponds to the transitory return to a primitive
condition, or, better, to the cyclical reappearance of some of
the features of Podophrya's ancestor.

The structures which develop before division, either in
the parent as a whole or only in the embryo or opisthe, are
characteristic of a phylogenetically primitive condition.

CHAPTER 10

Movements of the Ciliary System
in Ontogeny and Piiylogeny

An interesting and homogeneous group of ciliates lives in
the mantle cavity of bivalve molluscs. Among them is the
family of Hemispeiridae (= Ancistrumidae) . The somatic
system of kinetics is formed by longitudinal anteroposterior
rows with short cilia. A small sector of this somatic system
is thigmotactic. The preoral and oral systems are formed
by two long curved rows, having very long cilia, and ending
in the posterior oral infundibulum.

The three genera Ayicistrurn, Proboveria, and Boveria are
characterized and defined by the position of the origin of
the preoral system: anterior in Ancistrum, median in Pro-
boveria, posterior in Boveria. These three genera represent
three steps of an orthogenetic evolution: Ancistrum being
the primitive type, Proboveria intermediate, and Boveria
extreme [E. Chatton and A. Lwoff (1949)].

We shall first examine the division of Proboveria. Before
any visible sign of cytoplasmic constriction, the somatic
kinetics are cut approximately in their middle. The oral
system has migrated towards the anterior pole. The kine-
tics have become elongated and the kinetosomes have mul-
tiplied. The kinety 1, which is stomatogenic, will give rise
to various kinetics: kinety B and pharyngeal kinetics.
When the morphogenesis of the preoral and oral systems is
completed and when the proter and the opisthe are ready to
separate, they show the typical structure of the genus An-
cistrum. During growth, the preoral and oral systems w^ill

69

70

MORPHOGENESIS IN CILIATES

migrate towards the posterior pole. The adult structure is
thus formed.

In Boveria, the preoral system is entirely rolled up "on"

f g

Fig. 29. Evolution of Hemispeiridae. (a) Ancistrnm teUinae. (b)
Prohoveria loiipedis. (c) Boveria (schematic), (d) Posteroventral
view of Boveria^ showing the oral system, (e), (f) Division of Proho-
veria. Note the resemblance of the daughter ciliates to the adult Ancis-
trum. (g) Predivision of Boveria, showing the anterior position of the
oral ciliature. A to F, various preoral and oral kinetics.

the posterior ''pole" which has been modelled into a circular
surface. Before division takes place, the totality of the pre-
oral system migrates towards the anterior end and forms an

CILIARY SYSTEM, ONTOGENY AND PHYLOGENY 71

anteroposterior band. The phenomena, if not identical
with, are very similar to, those taking place in Proboveria.

Ancistruvi, Proboveria, and Boveria are obviously closely
related forms from the biological, morphological, cytologi-
cal, and developmental points of view. The position of the
origin of the preoral system is the main difference. As a
matter of fact, this position varies somewhat in some species
of Ancistrum.

It is difficult to escape the feeling that Hetnispeiridae
represents a monophyletic group and that Proboveria and
Boveria have originated from a common ancestor of the
Ancistrum type, w^hich is the primitive structural form of
the family.

Let us assume that the position of the oral system is the
consequence of "properties" of the cortex. We have to ad-
mit that, before division, constitution and structure of the
cortex, as judged by its effects on the oral system, are equiv-
alent to those of the primitive type.

The evolutionary series — Ancistrum -^Proboveria -^ Bo-
veria — consists in an anteroposterior migration of the oral
system which becomes enrolled on the posterior end. This
migration is reversed before division. The predivisional
type of structure corresponds to the phylogenetically primi-
tive state; the adult's structure, by definition, to the evolved
state. The movements of the oral system therefore appear
as the consequence of reversible changes of cytoplasmic
properties.

Evolution is generally considered to be irreversible.
What is irreversible in the ciliates we are considering is the
position of the preoral cilia in the mature ciliate, which is
the result of ontogeny as modified by evolution. But before
division, the preoral system moves towards the anterior
pole. This movement is reversible. What is irreversible is
the structure considered at a given phase of the life cycle.
The consideration of apostomatous ciliates leads to the same
conclusion.

72 MORPHOGENESIS IN CILIATES

It is generally admitted by protozoologists that one type,
if not the type, of primitive ciliate is the Prorodon type.
It has an anterior mouth, and diverging from it, a regular
set of anteroposterior longitudinal ciliary rows. The sym-
metry of the cortex is axial. This hypothetically primitive
type has been altered by the asymmetric development and
regression of some parts of the ciliary system, by the migra-
tions of the mouth, and by the development or alterations
of the oral system. A 'Ventral" and a ''dorsal'' face can be
recognized in many ciliates — for example, in Gymnodi-
iiioides or Foettingeria. But before division, a detorsion
takes place. The mouth disappears. The short postoral
rows become bipolar. The regular, bipolar, non-differenti-
ated anteroposterior ciliary system of the tomont corre-
sponds obviously to a primitive type of organization. And
here again, the primitive condition is regained before each
division.

Before discussing these facts we have to consider some
other types of ciliates, in which it is difficult to recognize
primitive and evolved features but which will provide good
material for concluding this discussion.

CHAPTER 11

Differeiiliation in Ciliates

Development of an organism, as already stated, may be
considered from the angle of cell diversification. Is it pos-
sible to trace homologous phenomena among ciliates? To
what extent are differences of the various sectors of a ciliate
equivalent to cell differentiation?

In apostomatous ciliates, these differences are, at least
partially, responsible for the specific structure of the ciliary
system. But, by definition, differentiation is not reversible.
And there often exists in cells of higher organisms a marked
antagonism between differentiation and division. Many
differentiated cells are unable to divide. Since ciliates di-
vide, one could be tempted to conclude that ontogenesis of
ciliates has in common with ontogenesis of Metazoa only its
quality of ontogenesis. Let us compare the morphogeneti-
cal processes in some ciliates.

In ciliates of the Leucophrys type, the proter and the
opisthe are modelled in the anterior and posterior parts of
the parent. The infra-equatorial part, between the kinety 1
(stomatogenic) and the last kinety n, becomes the oral zone
of the opisthe. In this case, apparently, no element of the
cortex has undergone irreversible change.

In the hypotrichous ciliate Euplotes, the argyrophylic
cortical network is entirely reorganized at each division,
starting from non-visible building blocks.

The oral ciliature of the opisthe will be formed by divi-
sion and organization of an anarchic field of kinetosomes.
The old parental structures disappear; cortical network and
cirri are reorganized : the parental mouth is reorganized into

73

74

MORPHOGENESIS IN CILIATES

the proter's mouth. As has been correctly noted by V.
Tartar (1941), '^Clearly differentiation and dedifferentiation
are here not conditions which characterize the cell as a

Fig. 30. Euplotes patella, (a) Ciliate in vivo, ci-cs, posterior cirrhi;
C.I., longitudinal crest; /1-/9, frontal cirrhi; /., undulating membrane;
p., pulsola; ti-to, transverse cirrhi; z.p., preoral zone, (b) Young
ciliate. (c)-(f) Predividing form, showing the new cirrhi and new net-
work. The peristome of the opisthe is formed from one kinetosome
originating from the posterior sector of the parental peristome, .e.z.,
developing oral zone of the opisthe; n.c, new cirrhi; n.z., new network.

whole but are quite local events which may occur simul-
taneously in different regions of the cell." It is quite obvi-
ous that many organelles are unable to divide. The "ro-
sette" of the apostomes lacks this ability. A new rosette

DIFFERENTTATTOX IN CTLTATES 75

has to be formed anew from the kiiiety x in each tomite.
And the mouth of many cihates behaves in the same way.
Differentiated organelles are very often unable to divide.

According to Tartar, ^'Ciliates show in a dramatic way
that cell division is not incompatible with differentiation.
The division period is in fact just the time of greatest for-
mation of new structures and the two processes of morpho-
genesis and division run parallel in time."

Of course, if differentiation is by definition considered
incompatible with cell division, ciliates are not differenti-
ated organisms. But the interval of time between two divi-
sions of Euplotes is 24 hours, and the morphogenetic proc-
esses start 8 hours before the cytoplasmic cleavage. As a
matter of fact, "division" is a very complicated process.
Two new^ "morphogenetic fields" are formed which organize
the proter and the opisthe in the anterior and posterior
parts of the parent. The differentiated structures of the
parent then disappear. "Division" stricto sensu separates
two highly differentiated ciliates. The important phenome-
non and the great mystery in this division are the formation
a long time before nuclear division of two "morphogenetic
fields." It is quite obvious that it is not a "differentiated"
ciliate which "divides" but that cleavage separates two al-
ready highly differentiated ciliates. The real division has
taken place 8 hours before, at the time where two new mor-
phogenetic fields have appeared. Although the old. differ-
entiated, parental structure is still there at this period, it is
nevertheless a dead structure, sentenced to dissolution and
disappearance. It is therefore clear that the term "differen-
tiation," considered as an irreversible modification of a cell,
cannot be applied without discussion to a non-cellular or-
ganism.

Differentiation in ciliates is synonymous with changes
occurring during morphogenesis or development. But this
organization, when considered independently of the phase
of the life cycle, is reversible. It is reversible because it rep-

76 MORPHOGENESIS IN CILIATES

resents essentially the sum of the movements of the kineto-
somes. Two new '^daughter-patterns" are formed anew at
each generation from one or many kinetosomes. The adult
ciliate is homologous to an adult organism. The "predivid-
ing" ciliate is, to a certain extent, homologous to an egg.
Let us remember that most of the apostomes can divide
only in the encysted stage, that is to say, after production,
like an egg of one, or even two, cystic membranes. Let us
remember also that the hypertomite of Phoretophrya and
the hypertrophont of Synophrya divide only some hours
before the ecdysis of the host. Their division is controlled
by an external stimulus and thereby recalls the activation
of the egg.

We have to remember that before each division the oral
kinetics of Proboveria and Boveria migrate towards the
anterior pole and take up a phylogenetically primitive posi-
tion. The situation is here very favorable because the
phylogenetic change we have considered is not a morpho-
logical "differentiation" but only a change in the position of
a system. The conditions, whatever they may be, which are
responsible for the movements and equilibrium of the oral
structures on the cortex are the result of the changes which
take place after division. Some phylogenetically primitive
condition reappears before each division. The study of
apostomatous ciliates in which a bipolar meridian pattern is
produced before division has already allowed the same con-
clusion. The differentiated cortex of highly evolved ciliates
may thus be compared to the differentiated cells of a meta-
zoan. The ''neutral" cytoplasm and the self-reproducing
units such as kinetosomes may be compared to the germinal
line, in the sense that they are responsible for the "creation"
of new organisms.

Thus, if we consider highly evolved ciliates, we see that
the "adult" is unable to undergo division. There is really
an antagonism between differentiation, in the sense of com-
plex productions of the adult, and division.

DIFFERENTIATION IN CILIATES 77

The ciliates have solved the j)rohlein of perpetuating
complex adult structure by cyclical dedifferentiation. The
life cycle of a ciliate is such that, after a certain period of
growth, something is changed in the unstable equilibrium
of some systems. The old structures disappear and the
properties of the predividing organism are such that phylo-
genetically primitive conditions and corresponding struc-
tures are formed.

Data on the chemistry of cell division are scarce. L. Rap-
kine has shown that in the sea-urchin egg, before division,
there is a considerable increase of the — SH groups. This
has been extended to apostomatous ciliates [E. Chatton.
A. Lwoff, and L. Rapkine (1931)]. But, except for this,
we have no data on the nature of the changes, and it ap-
pears of utmost importance to obtain information concern-
ing enzymatic activities preceding division in ciliates.

CHAPTER LJi

Interactions

of Morphogenetic Units

The process of orderly organization of the cortical net-
work of Podophrya parasitica which we have described is,
according to E. Faure-Fremiet.( 1945a), ''the transition be-
tween an amorphous state to an orderly state as if space
lattice forces have been responsible for a crystallization."
We do ^lot know yet whether the meshes of the parental
network disappear and are replaced by new structures or
are simply reshaped. The latter hypothesis seems to cor-
respond to the facts. Whatever the case may be, meshes
exist in the cortical network of the adult Podophrya, but
are differently arranged from those in the embryo. What
is the nature of the change? This is certainly an important
problem.

The ciliate Sphenophrya dosiniae possesses a sucker
which undergoes a considerable development. The organ-
ism is apparently stretched by this rigid structure. In the
mature ciliate, the posterior ''pole," that is to say, the point
where the posterior ends of the kineties join, is located ap-
proximately on the middle of one "face." The cortical net-
work is very irregular. Some meshes are small and more or
less regularly penta- or hexagonal; some, especially in the
posterior region, are considerably longer, just as if the sur-
face had been stretched. These are indications of some
elasticity of the surface during the growth of the organism.
But if the meshes were just elastic, their size and shape
would be regularized after completion of the growth. This

78

INTERACTIONS OF MORPHOOENETIC UNITS 79

is not the case. Things happen as if "tension forces" were
acting continuously, or as if meshes, extensible during de-
velopment, had turned into a rigid structure after the max-
imal size was reached.

f:-i/^'V^i^

^i •: •' J' * •'■•■ • ■■ • .*';

'^/H' :■■:.: •■*■■.

•^// ^•;7■■.•^*t;■/'••y^y

.'•V^.'

Fig. 31. Sphenophnja dosiniae. The meshes of the cortical network

are very elono;ate(l in the vicinity of the posterior region (between

the V formed by the posterior sectors of the cihary system).

80 MORPHOGENESIS IN CILIATES

The large network of an adult Euplotes also seems a rigid
structure, able to disappear only when replaced by the
newly formed meshes which enlarge or ''grow" during mor-
phogenesis of the daughter organisms. The "rigidity" of
the differentiated network is shown by starvation experi-
ments with the hypotrich Stylonychia mytilus, during which
the size of the organism decreases. The organism is re-
peatedly reorganized into a smaller organism during this
process [Dembowska (1938)].

We encounter great difficulties when we try to define
what may be considered as specific phenomena of a dividing
ciliate from the purely morphological point of view.

To analyze division in a very simple organism like a prim-
itive flagellate possessing one flagellum seems easy. Divi-
sion of the kinetosome is one of the first visible signs, and
precedes nuclear and cytoplasmic division. Some conditions
induce the division of one self-reproducing organelle. But
this does not mean that the division of self-reproducing or-
ganelles is responsible for the division of the organism.

In Gyvinodinioides, elongation of kineties a, x, y, z takes
place before division and seems ''specific" of division. Ob-
viously, some morphogenetic material induces the division
of the kinetosomes of these four ciliary rows. Synthesis of
some "morphogenetic material" thus appears as one of the
important phenomena preceding division. But one could
object that in regeneration also there is synthesis of mor-
phogenetic material. This is true.

Nevertheless, we may consider the complex association of
the cortical network with kinetosomes. The cortical net-
work, as has been shown, is a rigid structure in highly
evolved mature ciliates. On the contrary, kinetosomes may
multiply and increase in mimber as do other particles en-
dowed with genetic continuity.

We know that something in the cortical structure orients
the kinetosomes and the kinetodesmas. What mav be the

INTERACTIONS OF MORPHOOENETIC UNITS 81

relations of sucli an ''orienting system" to the oriented
material?

If something orientates kinetosomes, it can bo only by
virtue of some electronic or intermolecular forces. Let us
admit the hypothesis that the orienting system of an adult
ciliate is a rigid structure, unable to grow beyond certain
limits, as are the meshes of the cortical network. If the
kinetosomes continue to increase in number, the "reactive
groups" of the orienting system will finally become ''satu-
rated." The newly formed kinetosomes will find no place
to attach themselves. Their position will no longer be
controlled.

But if kinetosomes are normally bound to the orienting
system by electronic forces, this means that they have also
"reactive groups." Kinetosomes which are not bound to
the orienting system have ipso facto "non-saturated bonds"
able to attract or to aggregate free building blocks of the
orienting system. The free blocks would result from con-
tinued synthesis after the size limit of the orienting system
was reached. These blocks will now crystallize according
to their structure and environment and form new systems
or new organelles. We can propose as an example of this
type of phenomenon the attracting and orienting action of
the kinetosome in so many metazoan cells or Protozoa.
Certainly if one kinetosome is able to exert such an influ-
ence, groups of kinetosomes may have also a pow^erful
action.

In ciliates it is certain that multiplication of kinetosomes
precedes organization. The oral system, the membranelles
of Leucophrys or of Licnophora, are modelled in anarchic
kinetosomal fields. The cortical network of Euplotes is
formed around the newly formed fields of kinetosomes
which will produce the cirri. Strangely enough, the corti-
cal network of the ventral face of Euplotes develops sepa-
rately around the eight newdy formed cirri. There is not
one morphogenetic field for each daughter cell, but a series

82 MORPHOGENESIS IN CILIATES

of fields which will then fuse harmoniously into the charac-
teristic pattern of the parent.

Of course, when one tries to find what is really specific of
division, the only possible answer is: the duplication of the
differentiated structures, or the partial or total substitution
and superposition of two differentiated structures for the
unique parental structure; in other terms, the transition
between an organism with one morphogenetic field into an
organism with two morphogenetic fields.

In a dividing cell, with two asters surrounding kineto-
somes, the daughter kinetosomes act as if repulsing each
other. This model seems far too simple when we are deal-
ing with the duplication of morphogenetic '^fields." Never-
theless, the equilibrium of two interacting systems, one of
them being the kinetosomal system, seems to play an im-
portant role in morphogenesis and division of ciliates. This
hypothetical concept should of course be submitted to ex-
perimental control.

^But I want to emphasize that this conception of inter-
action of two — or more — systems is able to provide an ex-
planation of the cyclic formation of trichocysts. Let us
suppose that the maximal affinity of the kinetosome is for
the building blocks of the orienting system and for the
building blocks of cilia. Let us suppose that more kineto-
somes are formed than available units of these building
blocks, or that the relative speed of their synthesis is low.
This would result in "free" kinetosomes which would be
able to bind material for which the affinity is low, for ex-
ample, building blocks of trichocysts, the result being the
formation of trichocysts.

CHAPTER LS

Ontogeny in Ciliatcs
and the Diflferentiation
of Metazoan Cells

Morphogenesis of an animal may be considered the result
of cell differentiation. Only the germ line remains toti-
potent. The other cells become specialized, and develop-
ment results from the interaction of differentiated cells and
from the actions and interaction of the products of specific
activities of differentiated cells. An organism is the equili-
brated sum of differentiated cells. One of the problems
of development is the problem of the nature and origin of
cell diversification and specialization.

We know that the genome as a whole is a principle of
stability and that genes control enzymes. But development
is the story of diversification of cells possessing the very
same genome. It is convenient to visualize diversification
as the result of segregation of specific cytoplasmic particles,
which, with the collaboration of genes, would be responsible
for the synthesis of enzymes or group of enzymes. It is
possible also with P. Weiss (1949) to consider differentia-
tion as "si chain of events consisting of alternate physical
regrouping and chemical alteration of the molecular popula-
tions, the latter phenomenon involving the emergence of
novel species of compounds." Whatever our opinions on
differentiation may be, it happens that in many eggs deuto-
plasmic reserves of different types are unequally distributed.
Cleavage necessarily separates blastomeres possessing dif-
ferent reserves, that is to say, different types of metabolism.

83

84 MORPHOGENESIS IN CILIATES

We know that in euglenas such as Euglena jnesnili, the
relative speed of chloroplast multiplication and of cell divi-
sion may be altered in the absence of light [A. Lwoff and
H. Dusi (1935)]. This is an example, or a model, allowing
us to accept for the time being the hypothesis that, owing
to the nature of reserves, that is to say, of metabolism, cyto-
plasmic corpuscles can or cannot multiply, or multiply more
or less rapidly, and in some instance be lost in certain types
of cells. During development of the egg of the ctenophore
Beroe or of the mollusc DentaUum, substances such as
^'green ectoderm-producing substances" or '^non-colored en-
doderm-producing material" are synthesized. Whether
they are located in, or bound to, plasmagenes is not known.
Nevertheless, as these substances are unequally distributed,
cleavage brings about a segregation or localization of pre-
formed substances. During the development of the trocho-
phore larvae of molluscs, only some lines of cells produce
cilia. Obviously, kinetosomes have multiplied and have
produced cilia in certain types of cells only. Thus an or-
ganelle, the kinetosome, endowed wdth genetic continuity
may behave differently in different cells of an animal, just
as it behaves differently in different parts of a ciliate. Are
these two types of "differentiation," to some extent, com-
parable? Differentiation in a ciliate is essentially a cortical
phenomenon. To what extent is it possible to extend data
concerning ciliates to other animals? Is the cortex of a
ciliate something peculiar? Are the cortical phenomena
which occur in ciliates the specific expression of a general
law?

The importance of cell surface has been stressed by many
embryologists. E. E. Just (1939) went so far as to consider
that "in the entire animal kingdom, with the exception of
mammals, the embryo arises from the egg surface." E.
Faure-Fremiet and H. Mugard (1948) have discovered that
very important cortical phenomena take place during the

ONTOGENY IN FILIATES

85

development of Teredo norvegica. After the expulsion of
the second polar corpuscle, the surface of the egg is homo-
geneous as far as argyrophyly is concerned. But during
development, certain blastomeres show an increase of ar-
gyrophylic particles. These are the two blastomeres X is-
sued from D and blastomeres M and Y. They will give rise
to the cells of the shell gland, and to mesodermal and mes-
enchvmatous cells. Therefore, differentiation of the blasto-

FiG. 32. Teredo norvegica. Silver-impregnated morula.

mere is accompanied by cortical events. These events could
of course be the result as well as the cause of differentiation.
But in the last analysis we are compelled to ascribe differ-
entiation to the specific particles of the cell.

Is it possible to compare morphogenetic factors in ciliates
and Metazoa? We know that many parasitic Protozoa
show cytoplasmic differentiations in the region by which
they feed and that in ciliates nutrition interferes with mor-
phogenesis. Many eggs are attached to the ovary; they
have therefore a trophic region. This may account for the
formation of an axis. We know^ also, thanks to D. M.
Whitaker (1940), that in Fiicus the axis may be induced by
external factors such as light.

A. L. Cohen's (1942) principle of self-increasing com-
plexity is here very useful. According to this principle.

86 MORPHOGENESIS IN CILIATES

'^Once a certain degree of complexity is introduced into a
medium, the complexity will increase under its own mo-
mentum, physically, chemically, or both."

^'Given just the number of asymmetrical conditions in
the environment, the chemical complexity of protoplasm is
sufficient to evoke further spatial patterning. This, in turn,
increases the complexity of the gradients and phases and
so evokes a still more complex patterning, the whole cycle
repeating itself until the system has reached a condition of
dynamic stability or of rigidity as in fructification. But
development is a- perfectly orderly phenomenon; therefore,
segregation of particles must be controlled by severe and
unescapable laws. This is perhaps the reason for the suc-
cess of the cortical theories postulating an organization of
the cortex."

I should like to say that an orderly or organized asym-
metry, like that of an egg or of a ciliate, may only be the
reflection of cortical properties. A constantly flowing or
potentially flowing endoplasm cannot be asymmetrical.
The building blocks of the different organelles may be asym-
metrical; the organelles may be asymmetrical. But if we
consider the ciliate as an organism, we reach the conclusion
that organized asymmetry or simply organization can be-
long only to a more or less rigid, or more or less permanent,
system, that is to say, to the cortex.

It is known that the dextral or sinistral torsion of Lim-
naea is controlled by a pair of allelomorphic genes. But
the type of structure is determined not by the genetic con-
stitution of the organism, but by that of the oocyte from
which it arose. The direction of torsion depends on some
structure which is formed during the growth of the oocyte.
The hypothesis that this structure is cortical seems likely
and is in agreement with A. L. Cohen's statement (1942)
that "a surface is not a mathematical plane but a layer of
more or less oriented molecules or atoms with fields of
forces which in some instances may be quite powerful."

ONTOGENY IN CILIATES 87

The cortex is certainly very important, not only because
we have considered the surface of ciliates. And the con-
clusion that there is something in common in the ontogeny
of ciliates and the differentiation of metazoan cells during
development, namely, the organization of the cortex, seems,
for the time being, quite reasonable.

CHAPTER 14

The Kinetosome in Development,
Morphogenesis, and Evolution

Ciliates provide a model in which a cytoplasmic unit en-
dowed with genetic continuity and playing an important
role in morphogenesis is seen at work during developmental
processes. An important feature of the kinetosome is its
polyvalency. The fact that one specific particle is able to
synthesize types of organites as different from a functional
point of view as a cilium or a trichocyst is very suggestive.
Whatever the chemical parenthood of the two structures
may be, the facts show the importance of such particles.
Their loss or modification w^ould bring about the disappear-
ance of many functions. This explains perhaps the great
scarcity of plasmatic inheritance. It is possible that many
mutations of plasmatic particles are lethal because each par-
ticle controls many reactions.

The nature of the control of the alternative activities of
a cytoplasmic unit like the kinetosome remains an acute
problem. Many hypotheses may be considered when one
tries to understand the possible mechanism by which a
kinetosome is turned into a trichocystosome.

1. The hypothesis of a random mutation can be excluded
because all the kinetosomes of one ciliate produce a tricho-
cystosome at the same time.

2. The hypothesis of an induced mutation is difficult to
admit. The kinetosome divides into two particles, one re-
maining a kinetosome able to produce other ''normal" kine-
tosomes, that is to say, cilia-synthesizers. Is the difference

THE KINETOSOME IN DEVELOPMENT 89

between the two daughter organelles the result of an in-
duced unequational division? The kinetosonie has been
considered as a "unit." The evidence for doing so is only
morpholooical. that is to say, largely insufficient. A kineto-
sonie is large enough to be a complex of different molecular
species, living together side by side and generally multiply-
ing together. But it is possible that some conditions may
favor one molecular species. The unequational division
would thus correspond to an induced division of one part of
the kinetosonie. We can also admit that, if owing to a
changed environment one molecular species has ''grown"
more than others, division might give rise to a 'Vlisequili-
brated" or modified particle. Things look like an induced
unequational division only if we consider the kinetosonie as
a "unit."

3. But the possibility remains that kinetosomes and
trichocystosomes are in fact the product of a normal divi-
sion. Their different behavior could be due to different
factors :

a. Owing to its position far from the kinetodesma, the
trichocystosome could be in slightly different environmental
conditions from the kinetosome. We know that mitochon-
dria, for example, are not equally distributed in the cortex
of a ciliate [E. Chatton and S. Brachon (1935)].

b. The kinetosome remains attached, probably by a fiber
to the kinetodesma. This fiber may perhaps modify some
of its properties.

It is very difficult to make a choice among hypotheses 1,
2, and 3. It will be, in fact, impossible as long as the be-
havior of kinetosomes has not been submitted to an experi-
mental analysis. This should really be attempted. How-
ever, it must be recalled that in a flagellate such as Tricho-
monas one single kinetosome is able to give rise to a flagel-
lum, a fiber, an axostyle, and a parabasal body. These or-
ganelles may be chemically closely related, and it is possible
that their production corresponds to minute changes of the

90 MORPHOGENESIS IN CILIATES

metabolism of the kinetosome. But in some flagellates, as
well as in some ciliates, the only product of the kinetosome
is a cilium. This again may be due either to environmental
differences or to differences of the constitution of the kineto-
some itself. Transplantations, if they are possible, should
help solve the problem. What we see, in fact, is that under
apparently precise and perfectly unknown conditions one
granule produces what we may consider an orientated and
orderly polymerization of some material or materials (pro-
teins, polysaccharides, lipids).

Whatever the intimate cause of the polyvalency of kine-
tosomes may be, the polyvalency remains. The kinetosomes
themselves and their products are one mode of expression
of ciliate characters. And here is perhaps the main origi-
nality of ciliates. Most structures of highly differentiated
ciliates are rigid formations, unable to divide. But they
are able to undergo dedifferentiation, and apparently their
building blocks can be utilized again. The kinetosomes,
except when they are turned into trichocystosomes, main-
tain their primitive features. They remain able to divide,
to be organized in specific patterns together with other pro-
ductions of the ciliates.

What is rigid in evolved ciliates is the sum of the kineto-
somes + kinetodesmas + cortical network which consti-
tute the specific pattern. Differentiation in a ciliate is an
organization. But the properties of the whole organism
are not necessarily the sum of the properties of the constitu-
ent parts. The ciliate as an organism remains totipotent,
able to divide and to be reorganized. It can do this because
differentiation does not affect the whole organism, but only
its cortex, and because the responsible self-reproducing
cytoplasmic units are not them.selves changed during the
process of organization. And so we are able to understand
why a cyclical dedifferentiation is necessary in highly
evolved non-cellular organisms.

THE KIXF/rOSO:\IK IN DEVKLOI^MKXT 91

An analysis of the comparative niorpli()l()<!;y of ciliates has
led to the conclusion tliat th(^ period of pi'iMJivision cor-
responds to a phylogenetically primitive structure, whether
it is the pattern of kineties which is involved, or the posi-
tion of some specialized systems. A non-cellular organism
may therefore exhibit primitive and evolved features at
different phases of its cycle. But as a matter of fact,
changes are seen in the cortex only. Cortical events can
not be anything else than the reflection of chemical changes
controlled by enzymes and food. Nevertheless, the move-
ments of cortical particles, because these particles are or-
ganized, can be understood only if the hypothesis of inter-
actions between different types of associated particles is ad-
mitted. Any change in metabolism may bring about a
rupture of an unstable equilibrium, the multiplication of
some of the elements creating new poles of attraction, and
an origination of new morphogenetic fields.

Let us quote here another of Paul Weiss's statements
(1947): "No model of a cell can be pertinent unless it
takes into account both the elementary processes and their
organizational frame. Manifest cell organization results
from the response of organized elements to fields of or-
ganized (i.e., non-random) physical and chemical con-
ditions. . . ."

This statement, like the whole concept of "molecular
ecology," may be applied directly to ciliates. Molecular
ecology w^as a purely theoretical concept. The study of the
dynamic aspects of kinetosomes during ontogeny and phy-
logeny of ciliates illustrates the importance of self-reproduc-
ing particles in developmental phenomena.

This study also shows the importance of cortical struc-
ture in organization and finally leads to a hypothesis con-
cerning the interaction of the different building blocks
which may throw some light on the problems of division
and differentiation and on the mysterious fact that one
single particle can exhibit so many types of activity.

92 ^lORPHOGENESIS IN CILIATES

"Life," Louis Pasteur has written, "is dominated by
asymmetrical actions. I even foresee that all living species
in their structures, in their external forms, are primordially
functions of the cosmic dissymmetry."

The problems of the physicochemical aspects of organiza-
tion and of asymmetry have been extensively discussed by
E. Faure-Fremiet (1943, 1948b) in suggestive reviews to
which the reader should refer. Faure-Fremiet has clearly
considered the possibility of protoplasmic dissymmetry as
the initial factor of orientation and has posed the question :
"Are the spatial properties of an organized system deter-
mined by the anisotropic properties of molecules, or is the
orientation of molecular structure controlled by distinct
organizational factors?" The cell is a collection of mole-
cules — micelles and organelles. The environment of a par-
ticle is essentially the sum of other particles, and one can
question whether their spatial distribution, which is organ-
ization, is not the result of the interaction of the particles
themselves. The morphogenetical field would be the reflec-
tion of the properties and relative number of these particles.
Orienting forces would be the interplay of asymmetrical
molecules.

For example, the peritrichous ciliate Trichodina domer-
guei possesses a circular adhesive organ. This organ is
formed of articulated skeletal pieces of protein nature. After
the division, a new ring is formed. The skeletal proteins
are organized in a localized zone which behaves, according
to E. Faure-Fremiet and J. Thaureaux (1944), as a poly-
merization zone. In the formation of skeletal pieces, there
is a given orientation, a given direction, an asymmetrical
increase, the result of which is a specific organic structure.
The properties of such a polymerization zone are those of a
morphogenetic field.

The mechanist is intimately convinced that a precise
knowledge of the chemical constitution, structure, and
properties of the various organelles of a cell will solve bio-

THE KTXET(^SOME TX DEVEEOPMENT 93

logical problems. This will come in a few centuries. For
the time being, the biologist has to face such concepts as
orienting forces or mor]:)hogenetic fields. Owing to the
scarcity of chemical data and to the complexity of life, and
despite the progresses of biochemistry, the biologist is still
threatened with vertigo. That is why such clear models as
the formation of the skeletal pieces of a trichodine are very
comforting and useful.

Unfortunately, most of the constituent parts of the cell
are of suj3microscopical size. Therefore special attention
has to be given to the rare visible particles, especially to
those visible particles endowed with genetic continuity.
Such is the kinetosome.

Considering the history of protozoology, it may at first
sight seem strange that so many nature lovers of the old
times have been enchanted by ciliates. Of course, watching
a ciliate stopping in his search for food to look at you
through the microscope is most stirring. But my impres-
sion is that the lover of ciliates always had a presentiment
that ciliates were to be the proving ground for visible self-
reproducing particles. This is how and why we have con-
sidered ciliates.

Bibliography

The bibliography is divided into two parts:

1. A Hst of quoted papers among which the most important, includ-

ino- o-eneral discussions, are indicated by an asterisk (*).
2 \list of books or papers which, owing to the scope of the book,
■ have not been quoted or discussed but which are relevant to the
subject.

QUOTED PAPERS AND BOOKS

*Balamuth, W. 1940. Regeneration in Protozoa: a problem of
morphogenesis. Quart. Rev. BioL ^5. •290-337.

1949 Studies on the organization of cihate Protozoa: ii. Ke-

organization processes in Licnophora macfarlandi during bmary fis-
sion and regeneration. J. Exp. Zool.,91 :16-4S.

Caspari, E. 1948. Cytoplasmic inheritance. Advances m Genetics,

Chatton E 1921. Reversion de la scission chez les Cilies. Reahsa-
tion d'i'ndividus distomes et polyenergides de Glaucoma scintiUans se
multipliant indefiniment par scissiparite. Compt. rend. acad. sci.,

173 '393-397

■ 1994 " Sur les connexions flagellaires des elements flagelles.

Centrosomes et mastigosomes. La cinetide, unite cineto-flagellaire.
Cinetides simples et cinetides composees. Compt. rend. soc. bioL,

9^ .•577-581. , . ,

1931 E'^sai d'un schema de Tenergide d'apres une image ob-

jective^t"synthetique: le Dinoflagelle Pohjkrikos SchwartziBui.chh.
Compt. rend. X/^'"^ Congres International de Zoologie, Padova, IbJ-

187, pi. III-IV. . . ^ ,

Chatton, E., and S. Brachon. 1935. Discrimmation, chez deux

Infusoires du genre Glaucoma, entre systeme argentophile et in-

fraciliature. Compt. rend. soc. bioL. 118:399.
* Chatton, E., and A. Lwoff. 1935a. Les Cilies apostomes L

Apercu historique et general; etude monographique des genres et des

espec^s. Arch. zool. exp. et gen.. 77 .'1-453, 21 pi., 217 fig.

95

96 BIBLIOGRAPHY

* Chatton, E., and A. Lwoff. 1935b. La constitution primitive de

la strie ciliaire des infusoires. La desmodexie. Compt. rend. soc.

hiol, i^5;1068-1072.
. 1936. La division et la continuite du cinetome chez I'Ancistru-

mide Prohoveria loiipedis, n.g., n. sp., de Loripes lacteus. Arch. zool.

exp. et gen., 78, N. et i^.. -84-91.

1949. Recherches sur les Cilies thigmotriches. Arch. zool. exp.

et gen., 5^ .-169-253.
Chatton, E., A. Lwoff, and M. Lwoff. 1929. Les infraciliatures et

la continuite genetique des systemes ciliaires recessifs. Compt. rend.

acad. sci, 188:1190-1192.
. 1931a. L'infraciliature de Tlnfusoire Thigmotriche Spheno-

phrya dosinise (Ch. et Lw.). Structure, topographie, et developpe-

ment. Compt. rend. soc. hiol., 107 : 532-535.
. 1931b. L'origine infraciliaire et la genese des trichocystes et

des trichites chez les Cilies Foettingeriidse. Comp. rend. acad. sci.,
193. -670-673.

Chatton, E., A. Lwoff, M. Lwoff, and J. Monod. 1931. La for-
mation de 1 ebauche buccale posterieure chez les Cilies en division et
ses relations de continuite avec la bouche anterieure. Compt. rend,
soc. hiol, i07 .-540-544.

Chatton, E., A. Lwoff, M. Lwoff, and L. Tellier. 1929. L'infra-
ciliature et la continuite genetique des blepharoplastes chez I'Acinetien
Podophrya fixa 0. F. IMuller. Compt. rend. soc. hiol., ^W. -1191-1196.

Chatton, E., A. Lwoff, and L. Rapkine. 1931. L'apparition de
groupements SH avant la division chez les Foettingeriidx (Cilies).
Compt. rend. soc. hiol., iO^ .-626-629.

Chatton, E., and J. Sequela. 1940. La continuite genetique des
formations ciliaires chez les Cilies hypotriches. Le cinetome et Tar-
gyrome au cours de la division. Bidl. hiol. France-Belgique, 74 :
349-442.

Cohen, A. L. 1942. The organization of protoplasm: a possible ex-
perimental approach. Growth, 6" .'259-272.

Darlington, C. D. 1939. The Evolution of Genetic Systems. Uni-
versity Press, Cambridge.

. 1944. Heredity, development, and infection. Nature. Lond.,

i54 .-164-169.

Dembowska,, W. 1938. Korperreorganisation von Stylonychia mytilus
beim Hundtern. Arch. /. Protistenk., 91 .-89-105.

DoBELL, C. (5 191]. The principles of protistology. Arch. j. Protis-
tenk., ^.5.-260-310.

* Faure-FreJiiet, E. 1943. Le probleme de Torganisation et ses as-
pects physicochimiques. Revue scientifique, fasc. 5. -433-446.

BIBrJOOKAPHY 97

*Faure-Fremiet, E. 1945a. I^odopJinja parasitica, nov. sp. Bull.

biol. France-Belgiqiie, 7-9 /So.
* . 19451). Symetrie et lujlarih'' choz les cilies; bi- ou multicom-

posites. Bull. biol. France-Belgique, 7,9;10r)-150.
* . l!)48a. Doublets homopolaires ct roffulation niorphogenetiqvie

chez le cilie Leucophrys patula. Arch. anat. microscop. et rnorphol.

exp., 57 .-183-203.
* . 194Sb, Les mecanismes de la niorphogenese chez les cilies.

Folia Biotheoretica, 7/7. -25-58.
Faure-Fremiet, E., and H. Mugard. 1948. Seojresation d'lm materiel

cortical an coiirs de la segmentation chez rneuf de Teredo norvegica.

Compt. rend. acad. sci., ^^7.-1400-1411.

* Faure-Fremiet, E., and J. Thaureaux. 1944. Proteines de strnc-

ture et cytosqiielette chez les Urceolarides. Bull. biol. France-Bel-
giqiie, 75 .-143-156.

* Harrison, R. G. 1937. Eml)ryoloiiy and its relations. Science,
5J .-369-374.

Huxley, J. S., and G. R. de Beer. 1934. The Elements of Experi-
mental Embryology. University Press, Cambridge.

Just, E. E. 1939. The Biology of the Cell Surface. P. Blakiston,
Philadelphia.

LwoFF, A. 1944. Levolution physiologique. Etude des pertes de
fonctions chez les microorganismes. Hermann, Paris.

— — . 1949a. Discussion du rapport Sonneborn et Beale. In Colloqiie
Unites biologiques donees de continuite genetique. Centre National
de la Recherche Scientifique, Paris, p. 35.

* . 1949b. Les organites doiies de continuite genetique chez les

protistes. In Colloque Unites biologiques donees de continuite gene-
tique. Centre National de la Recherche Scientifique, Paris.

LwoFF, A., and H. Dusi. 1935. La suppression experimentale des
chloroplastes chez Euglena mesnili. Compt. rend. soc. biol., 119 :IQ^2.

MoNOD, J. 1947. Enzymatic adaptation, its bearing on problems of
genetics and cellular differentiation. Growth Symposium, ^^.-223-289.

Mugard, H. 1947. Division et niorphogenese chez les Ophryoglenes.
Compt. rend. acad. sci., 225 :7(}-72.

ScHMiTT, F. 0. 1941. Some protein patterns in cells. Growth Sym-
posium, J. -1-20.

SiNNOTT, E. W. 1939. The cell-organ relationship in plant organiza-
tion. Growth, 5.-77-86.

Sonneborn, T. M., and G. H. Beale. 1949. Influence des genes, des
plasmagenes, et du milieu dans le determinisme des caracteres antige-
niques chez Paramecium aurelia (variete 4). In Colloque Unites

98 BIBLIOGRAPHY

biologiques douees de contiiiuite genetique. Centre National de la
Recherche Scientifique, Paris.

* Tartar, V. 1941. Intracellular patterns: facts and principles con-
cerning patterns exhibited in the morphogenesis and regeneration of
ciliate protozoa. Growth, o :2S.

Villeneuve-Brachon, S. 1940. Recherches sur les cilies heterot riches.
Arch. zool. exp. et gen., S^ ."1-180.

Weiss, P. 1947. The problem of specificity in growth and develop-
ment. Yale J. Biol, and Med., 19:235-278.

Weiss, P. 1949. Differential growth. In Chemistry and Physiology
of Growth, edited by A. K. Parpart. Princeton University Press.

Whitaker, D. M. 1940. Physical factors of growth. Growth, 4 -'75-90.

Wright, S. 1941. The physiology of the gene. Physiol. Rev., 21 . '487-
527.

RELEVANT BOOKS AND PAPERS

AsTBURY, W. T. 1945. The forms of biological molecules. In Essays

on Growth and Form. Clarendon Press.
Berrill, N. J. 1941. Spatial and temporal growth patterns in colonial

organisms. Growth, J. '89-111.
Blakeslee, a. F. 1941. Growth patterns in plants. Growth, 5 :77-88.
Harrison, R. G. Cellular differentiation and internal environment.

Amer. Assoc. Adv. Science, no. 14:77-97.
. 1945. Relations of symmetry in the developing embryo. Trans.

Conn. Acad. Arts and Sciences, 5^ .-277-330.
Raper, K. B. 1941. Developmental patterns in simple slime molds.

Growth, 5/69-74.
Tyler, A. 1947. An auto-antibody concept of cell structure, growth,

and differentiation. Growth Syyn/posium, 7-19.
Weiss, P. 1939. Principles of Development. Henry Holt, New York.
. 1949. Differential growth. In Chemistry and Physiology of

Growth, edited by A. K. Parpart. Princeton University Press.
Wright, S. 1945. Genes as physiological agents. General considera-
tions. Amer. Nat., 7P .-289-303.

Index

Adaptive enzymes and kinetosomes,

31
Ancistrum, 69
Ancistrumidae , 69
Antigens, 46
Apotomy, 37 (Fig. 11)
Asymmetry, and cortex, 86

and equilibrium, 61

and kinctodesma, 11, 60, 61

and life, 86, 92

origin, 72

Balamuth, W., 47

Basal disc of Licnophora, 47, 48

Beale, G., 46

Beroe, 84

Blepharoplast in flagellates, 6

Boveria, 69-76

Brachet, J., 16

Caspari, E., 2

Centriole and kinetosome, 5, 7

Chatton, E., 7, 61

Chatton, E., and S. Brachon, 89

Chatton, E., and A. Lwoff, 11, 43, 62

Chatton, E., and A. and M. Lwoff, 7,

19
Chatton, E., A. Lwoff, and J. Monod,

47
Chatton, E., A. Lwoff, and L. Rap-

kine, 77
Chatton, E., A. and M. Lwoff, and L.

Tellier, 65
Chloroplast, 84
Chromidina elegans, 44, 45 (Fig. 16)

division, 64
Cilia, and kinetosomes, 20

and life cycle, 22

in life cycle of suctorians, 67

origin in suctorians, 65

Ciliary antigens, 46

Cohen, A. L., 29, 85, 86

Cortex, and differentiated cells, 76

and differentiation, 90

and evolution, 71

and heterotomy, 64

and ontogeny, 87

equilibrium, 50

fields, 86

in Teredo, 84
Cortical pattern, 51, 62
Crystalline network, 61
Cytoplasm, and inheritance, 2, 3

in development, 2

Dalcq, A., and J. Brachet, 16
Dalcq, A., and J. Pasteels, 16
Darlington, C, 4, 33
Dedifferentiation, 74, 77-90
Dembowska, W., 80
Dentalium, 84
Desmodexy, law of, 11
Detorsion of Gymnodinioides, 11
Development, and cytoplasm, 2

in general, 1
Differentiation, 73-77

and cortex in molluscs, 84, 85

and cyclical phenomena, 77

and division, 74, 75, 76

and ontogeny, 83-87

and organization, 90

and plasmagenes, 34

and reserves, 84

and specialization, 1

in ciliates, 33

in Eiiplotes, 74

in multicellular organisms, 33
Division, and differentiation, 75, 76,
77

and morphogenesis, 36

99

100

INDEX

Division, and nutrition, 64

induced, 37, 40, 41

unequal, 64
Dobell, C, 2
Doublet, 62
Dusi, H, 84

Ecology, see Molecular ecology
Embryo of suctorians, 65
Equilibrium, 61-64

and asymmetry, 61

and cortical pattern, 62

and division, 76

of interacting systems, 82

of kineties, 50

of structures, 76
Euglena mesnili, 84
Eupagurus hernhardus, 9
Euplotes patella, 74 (Fig. 30)

division, 73, 74

morphogenesis, 81

organization, 73
Evocator, 16
Evolution, 69-72

and division, 71

apostomes, 72

Hemispeiridae, 69, 70

irreversibility, 71

reversibility, 71

suctorians, 68

Faure-Fremiet, E., 61, 62, 65, 78
Faure-Fremiet, E., and H. Mugard,

84
Faure-Fremiet, E., and J. Thau-

reaux, 92
Fibers and morphogenesis, 46, 60
Field, see Morphogenctic field

and organization, 91
Flagellates, centriole of, 7
Foettingeria, detorsion, 58

life cycle, 24

palintomy, 56

tomitogenesis, 57

trichites, 20 (Fig. 7), 24, 25 (Fig.
10)

trichocysts, 24, 25 (Fig. 10)

Foettingeria, trophont, 55
Forces, electronic, 81

in cortical field, 86

intermolecular, 81

lattice, 78

tension, 79
Fucus, 85

Gargarius, 29

Gene, and differentiation, 34, 83

and plasmagene, 30

and specific activity, 35
Genetic continuity in general, 1-8
Glaucoma piriformis, 47
Glaucoma scintillans, 47
Gradient inhibition, 64
Gymnodinioides inkystans, 9-18

kinety, 6 (Fig. 1)

life cycle, 9, 10

palintomy, 14 (Fig. 4), 15 (Fig. 5)

tomite, 13 (Fig. 3b)

tomitogenesis, 17 (Fig. 6)

tomont, 14 (Fig. 4), 15 (Fig. 5)

trophont, 12 (Fig. 3)

Harrison, R., 2

Hemispeiridae, 69

Huxley, J., and G. de Beer, 17

Hyperpalintomy of Synophrya, 39

"^(Fig. 13), 41
Hypertomont, 40 (Fig. 14)
Hypertrophont, 39

Ichthyophthirius multifiliis, 50
Infraciliature, definition, 7

morphogenesis, 62
Interactions, and organization, 91

of kinetosomes, 80

of morphogenetic units, 78-82

of systems, 82
Intermolecular forces, 81

Just, E. E., 84

Kinetodesma, and desmodexy. 11, 61
and detorsion, 54
and disorder, 52, 54

INDEX

101

Kinetodesma, and order, 52, 54

and shortening. 60

and stretching, 54

and torsion, 54, 58, 59
Kinetophist, 19
Kinctosome, and eentriole, 7

and ciliiim, 29, 30

and differentiation, 33

and disorder, 52

and Hfe cycle, 20

and morphogenetic field, 33

and nutrition, 67

and order, 52

and trichocystosomes, 31, 32

as a self-reproducing unit, 26

as a unit, 89

definition, 5

genetical continuity, 5, 6, 7

illustrated. 6 (Fig. 1)

in flagellates, 7

in Foettingena, 6 (Fig. 1)

in Gymnodinioides, 6 (Fig. 1)

in Polyspira, 6 (Fig. 1)

interactions, 78-82

mutation, 45, 46

polyvalency, 90

population, 42

potentiality in flagellates, 89

prospective potencies, 20

specialization, 47
Kinet}^ autonomy, 47

equilibrium, 61-64

genetic continuity, 42-51

length, 62

movements and evolution, 69-72

regulation of number, 50

reproduction, 42-51

specialization, 47

stomatogenic, 47

structure, 6 (Fig. 1)

variation of number, 50

Lattice forces, 78

Leucophrys patula, doublet, 61

Leucophrys piriformis, division, 73

doublet, 61
Licnophora chattoni, 47

Licnophora macfnrhindi, 48, 49

Life cycle, of Gymnodinioides, 10
(Fig. 2)
of Phoretophrya, 38 (Fig. 12)
of Polyspira, 21 (Fig. 8)
of Synophrya, 39 (Fig. 13)

Limnea peregrea, 59, 86

Lwoff, A., 7, 11, 19, 43, 47, 62, 63. 65,
77

Lwoff, A., and H. Dusi, 84

Lwoff, A., and M. Lwoff, 7, 19, 47, 65

Migration of oral system, 76
Modulation, 3

Molecular ecology, and differentia-
tion, 83

and kinetosomes, 27, 28, 32

and organization, 91

in general, 3, 4, 5
Monod, J., 31, 47
Monsters, 61

Morphogenesis, and apotomy, 36, 37,
38

and division. 36-41

and kinetosomes, 62

in higher animals, 33

of hypertomite, 40 (Fig. 14)
Morphogenetic field, 17, 18

and behavior of kinetosomes, 29

and development of Gymnodini-
oides, 16, 17, 18

and interactions, 82

and polymerization, 92

duplication, 75, 82

in Euplotes, 75, 81
Morphogenetic substance and tricho-

cyst, 64
Mouth, formation in Glaucoma, 47

formation in Leucophrys, 47, 48
(Fig. 17)

formation in Licnophora, 47, 49
(Fig. 18)

migrations, 69

regeneration, 46, 47
Mugard, H., 50, 84
Mutation of kinetosomes, 34, 45, 46

102

INDEX

Nebalia, 36

Network (cortical), and interaction,
81

and kinetosomes, 80

and organization, 65

formation, 75

in Euplotes, 74 (Fig. 30), 80

in Podophrya, 66 (Fig. 27)

in Sphenophrya, 78, 79 (Fig. 31)

in Stylonychia, 80

in suctorians, 65-68
Nutrition, and division, 63, 64

and organization, 67

7 ^

Ontogeny, 69|-72, 83-87
Order and kaetodesma, 60
Organization, ahd kinetosomes, 81

and nutrition, 67

and reproductiofi, 65-68
Orienting system, S\
\

Palintomy, of Gymnodinioides, 12,
13, 14 (Fig. 4). 15 (Fig. 5)

of Phoretophrya, 38 (Fig. 12)

of Synophrya, 39 (Fig. 13), 41
Paramecium, 46, 47
Pasteels, J., 16
Pasteur, L., 92
Pelecyophrya, 29

Pericaryon cesticola, 43, 44 (Fig. 15)
Phoretophrya nebaliae, 36, 38 (Fig.
12), 40

hypertomite, 54
Phoront of Gym,nodinioides, 9
Phylogeny, 69-72

in suctorians, 68
Plagiospira crinita, 63
Plasmagenes, and antigenic types, 46

and biological corpuscle, 4

and cytoplasmic inheritance, 2, 3

and gene, 30

and kinetosomes, 32, 33

as relic, 33

as residues, 4

in development, 3, 34
Podophrya fixa, 64, 66

Podophrya parasitica, 65, 67
and organization, 78

Polymerization and morphogeny, 92

Polyspira delagei, life cycle, 21 (Fig.
8), 23 (Fig. 9)

Populations of kinetosomes, 42

Proboveria, 69, 76

Prorodon, 72

Prospective potencies of kineto-
somes, 30

Protozoa as organisms, 2

Rapkine, L., 77
Regeneration, 62

in Licnophora, 47, 49

in Param^ecium, 46, 47

of basal disc, 47, 48

of mouth, 46
Regulation of kineties, 50
Reversibility, of evolution, 70

of organization, 75
Rosette, and kineties, 43

of Gymnodinioides, 11

Schmitt, F. 0., 60

Segregation, and differentiation, 34,
83

of kinetosomes, 33

of particulate material, 2
Sepia elegans, 64
Sinnott, E. W., 29
Sonneborn, T., and G. Beale, 46
Specialization, of kineties, 47

kinetosomes, 47
Sphenophrya, 29
Sphenophrya dosiniae, 78, 79
Sphenophryidae, 29
Stomatogenesis, see Mouth
Stylonychia mytiliis, 80
Suctorians, 29, 65-68
Surface, 29
Synophrya hypertrophica, 37, 38, 39

(Fig. 13), 40 (Fig. 14)

Tartar, V., 46, 74, 75
Tellier, L., 65
Teredo norvegica, 85

INDEX

103

Tetrahymena gelcii, 47

Thigniotricha, 62

Toinito of Gyninodiniuulcs, 9, 12

(Fig. 3b)
Tomitogcncsis, of Chromidina, 44
(Fig. 16)
of Gynutodinioidcs, 15 (Fig. 5),

17 (Fig. 6)
of Polyspira, 23 (Fig. 9)
Tomont of Gynniodinioidcs, 9
Torsion, 52-60

of Limnea, 58, 59, 86
Traumatiophtora punclnta, 52. 53

(Fie. 19)
Trichites, 20 (Fig. 7)
in Foettingeria, 24
Trichitosomes of Foettingeria, 24, 25

(Fig. 10). 30
Trichocyst, 19-26
and interactions, 82
in Chromidina, 64
of Foettingeria, 25 (Fig. 10)
of Gyvmodinioides, 20 (Fig. 7)

Tricliocysl , of Polyspira, 6 (Fig. 1),
20 (Fig. 7)

origin in Fucttlngi ria, 24

origin in Gymnodinioides, 19

origin in Polyspira, 24
Tricliocy.stosomo, and adaptive en-
zymes, 31

and kinetosome, 31

in Gyninodinioidcs, 20

in Polyspira, 24, 30, 32

origin, 88
Tricliodina domergnei, 92
Trophont, of Foettingena, 55 (Fig.
21), 58 (Fig. 24)

of Gymnodinioides, 9, 12 (Fig. 3)

of Pericaryon, 44 (Fig. 15)

of Traumatioplitora, 53 (Fig. 19)

structure, 11

Villeneuve-Brachon, S., 47

Weiss, P., 3, 27. 28, 32, 83-91
Whitaker, D. M.. 85
Wright, S., 26, 30

'vm i

V'^.

, .1 J'f^'f'^