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Professor of Zoology 

The University of Illinois 

Urbana, Illinois 

With three hundred and seventy-six illustrations 

Fourth Edition 


Springfield, Illinois • U.S.A. 

Charles C Thomas • Publisher 

Bannerstone House 

301-327 East Lawrence Avenue, Springfield, Illinois 

Published simultaneously in the British Commonwealth oj Nations by 
Blackwell Scientific Publications, Ltd., Oxford, England 

Published simultaneously in Canada by 
The Ryerson Press. Toronto 

This monograph is protected by copyright. No 
part of it may be reproduced in any manner 
without written permission from the publisher. 

Copyright 1931, 1939, 1946, and 1954 by Charles C Thomas • Publisher 

First Edition, January, 1931 

Second Edition, September, 1939 

Third Edition, January, 1946 

Third Edition, Second Printing, November, 1947 

Third Edition, Third Printing, August, 1950 

Fourth Edition, September, 1954 

Library of Congress Catalog Card Number: 54-6567 

Printed in the United States oj America 

"The revelations of the Microscope are perhaps not 

excelled in importance by those of the telescope. 

While exciting our curiosity, our wonder 

and admiration, they have proved of 

infinite service in advancing our 

knowledge of things 

around us." 





THE fourth edition of Protozoology maintains its original aim in 
setting forth "introductory information on the common and rep- 
resentative genera of all groups of both free-living and parasitic 
Protozoa" for seniors and graduates in zoology in colleges and uni- 
versities. It has been noted in recent years that students frequently 
wished to obtain a fuller knowledge on certain topics, organisms, 
processes, etc., than that which was found in the former edition. In 
order to meet this need without too great an expansion, references 
have been given to various items in the text and a list of a much 
larger number of literature has been appended to each chapter. 
Furthermore, this enlargement of references increases the usefulness 
of this work to advanced students, teachers of biology, field workers 
in various areas of biological science, veterinarians, physicians, pub- 
lic health workers, laboratory diagnosticians and technicians, etc. 

While the chapter arrangement remains the same as before, a 
thorough revision has been carried on throughout the text in the 
light of many recently published contributions to protozoology. 
Good illustrations are indispensable in this kind of work, since they 
are far more easily comprehended than lengthy statements. There- 
fore, old illustrations were replaced by more suitable ones and many 
new illustrations have been added, bringing up the total number of 
the text figures now to 376. Except diagrams, all figures are accom- 
panied by the scales of magnification. For illustrations that have 
been adopted from published papers, the indebtedness of the author 
is expressed by mentioning the authors' names. 

R. R. Kudo 
Urbana, Illinois 


Preface vii 

Part I: General biology 3 


1 Introduction 5 

Relationship of protozoology to other fields of 
biological science, p. 6; the history of protozool- 
ogy, p. 10. 

2 Ecology 20 

Free-living Protozoa, p. 20; parasitic Proto- 
zoa, p. 28. 

3 Morphology 39 

The nucleus, p. 40; the cytoplasm, p. 45; loco- 
motor organellae, p. 49; fibrillar structures, p. 
60; protective or supportive organellae, p. 70; 
hold-fast organellae, p. 76; parabasal appa- 
ratus, p. 77; Golgi apparatus, p. 78; chondri- 
osomes, p. 80; contractile and other vacuoles, p. 
83; chromatophore and associated organellae, 
p. 89. 

4 Physiology 97 

Nutrition, p. 97; reserve food matter, p. 112; 
respiration, p. 116; excretion and secretion, p. 
118; movements, p. 122; irritability, p. 130. 

5 Reproduction 145 

Nuclear division, p. 145; cytoplasmic division, p. 
166; colony formation, p. 173; asexual repro- 
duction, p. 175; sexual reproduction and life- 
cycles, p. 180; regeneration, p. 212. 

6 Variation and heredity 223 

Part II: Taxonomy and special biology 247 


7 Major groups and phylogeny of Protozoa 249 

8 Phylum Protozoa 254 

Subphylum 1 Plasmodroma 254 

Class 1 Mastigophora 254 

Subclass 1 Phytomastigina 256 

Order 1 Chrysomonadina 256 





9 Order 2 Cryptomonadina 272 

10 Order 3 Phytomonadina 276 

11 Order 4 Euglenoidina 293 

Order 5 Chloromonadina 306 

12 Order 6 Dinoaagellata 310 

13 Subclass 2 Zoomastigina 333 

Order 1 Rhizomastigina 333 

14 Order 2 Protomonadina 339 

15 Order 3 Polymastigina 369 

16 Order 4 Hypermastigina 404 

J 7 Class 2 Sarcodina 417 

Subclass 1 Rhizopoda 418 

Order 1 Proteomyxa 418 

18 Order 2 Mycetozoa 427 

19 Order 3 Amoebina 435 

20 Order 4 Testacea 472 

21 Order 5 Foraminifera 493 

22 Subclass 2 Actinopoda 505 

Order 1 Heliozoa 505 

23 Order 2 Radiolaria 516 

24 Class 3 Sporozoa 526 

Subclass 1 Telosporidia 526 

Order 1 Gregarinida 527 

25 Order 2 Coccidia 570 

26 Order 3 Haemosporidia 599 

27 Subclass 2 AcnidQsporidia 635 

Order 1 Haplosporidia 635 

Order 2 Sarcosporidia 638 

28 Subclass 3 Cnidosporidia 643 

Order 1 Myxosporidia 643 

Order 2 Actinorayxidia 660 

29 Order 3 Microsporidia 668 

Order 4 Helicosporidia 678 

30 Subphylum 2 Ciliophora 683 

Class 1 Ciliata 683 

Subclass 1 Protociliata 685 

31 Subclass 2 Euciliata 690 

Order 1 Holotricha 690 

Suborder 1 Astomata 691 

32 Suborder 2 Gymnostomata 700 

Tribe 1 Prostomata 700 

33 Tribe 2 Pleurostomata 723 


Tribe 3 Hypostomata 728 

34 Suborder 3 Trichostomata 737 

35 Suborder 4 Hymenostomata 758 

36 Suborder 5 Thigmotricha 774 

37 Suborder 6 Apostomea 789 

38 Order 2 Spirotricha 796 

Suborder 1 Heterotricha 796 

39 Suborder 2 Oligotricha 814 

40 Suborder 3 Ctenostomata 829 

41 Suborder 4 Hypotricha 832 

42 Order 3 Chonotricha 847 

43 Order 4 Peritricha 850 

44 Class Suctoria 863 

45 Collection, cultivation, and observation of Protozoa 879 

Author index 905 

Subject index 919 



Chapter 1 

PROTOZOA are unicellular animals. The body of a protozoan 
is morphologically a single cell and manifests all characteristics 
common to the living thing. The various activities which make up 
the phenomena of life are carried on by parts within the body or cell. 
These parts are comparable with the organs of a metazoan which are 
composed of a large number of cells grouped into tissues and are 
called organellae or cell-organs. Thus the one-celled protozoan is a 
complete organism somewhat unlike the cell of a metazoan, each of 
which is dependent upon other cells and cannot live independently. 
From this viewpoint, certain students of protozoology maintain 
that the Protozoa are non-cellular, and not unicellular, organisms. 
Dobell (1911), for example, pointed out that the term "cell" is 
employed to designate (1) the whole protozoan body, (2) a part of 
a metazoan organism, and (3) a potential whole organism (a fertilized 
egg) which consequently resulted in a confused state of knowledge 
regarding living things, and, therefore, proposed to define a cell as 
a mass of protoplasm composing part of an organism, and further 
considered that the protozoan is a non-cellular but complete organ- 
ism, differently organized as compared with cellular organisms, the 
Metazoa and Metaphyta. Although some writers (Hyman, 1940; 
Lwoff, 1951) follow this view, the great majority of protozoologists 
continue to consider the Protozoa as unicellular animals. Through 
the processes of organic evolution, they have undergone cytological 
differentiation and the Metazoa histological differentiation. 

In being unicellular, the Protozoa and the Protophyta are alike. 
The majority of Protozoa may be distinguished from the majority of 
Protophyta on the basis of dimensions, methods of nutrition, direc- 
tion of division-plane, etc. While many Protophyta possess nuclear 
material, it is not easy to detect it in many forms; on the other hand, 
all Protozoa contain at least one easily observable nucleus. The 
binary fission of Protozoa and Protophyta is longitudinal and trans- 
verse respectively. Most of Ciliata, however, multiply by transverse 
division. In general the nutrition of Protozoa is holozoic and of 
Protophyta, holophytic or saprophytic; but there are large numbers 
of Protozoa which nourish themselves by the latter methods. Thus 
an absolute and clean-cut separation of the two groups of unicellular 
organisms is not possible. Haeckel (1866) coined the name Protista 
to include these organisms in a single group, but this is not generally 


adopted, since it includes undoubted animals and plants, thus creat- 
ing an equal amount of confusion between it and the animal or the 
plant. Calkins (1933) excluded chromatophore-bearing Mastigoph- 
ora from his treatment of Protozoa, thus placing organisms similar 
in every way, except the presence or absence of chromatophores, in 
two different (animal and plant) groups. This intermingling of char- 
acteristics between the two groups of microorganisms shows clearly 
their close interrelationship and suggests strongly their common 

Although the majority of Protozoa are solitary and the body is 
composed of a single cell, there are several forms in which the 
organism is made up of more than one cell. These forms, which are 
called colonial Protozoa (p. 173), are well represented by the mem- 
bers of Phytomastigina, in which the individuals are either joined by 
cytoplasmic threads or embedded in a common matrix. These 
cells are alike both in structure and in function, although in a few 
forms there may be a differentiation of the individuals into repro- 
ductive and vegetative cells. Unlike the cells in a metazoan which 
form tissues, these vegetative cells of colonial Protozoa are not so 
dependent upon other cells as are the cells in Metazoa; therefore, 
they do not form any true tissue. The reproductive cells produce 
zygotes through sexual fusion, which subsequently undergo repeated 
division and may produce a stage comparable with the blastula stage 
of a metazoan, but never reaching the gastrula stage. Thus, colonial 
Protozoa are only cell-aggregates without histological differentiation 
and may thus be distinguished from the Metazoa. 

An enormous number of species of Protozoa are known to man. 
From comparatively simple forms such as Amoeba, up to highly 
complicated organisms as represented by numerous ciliates, the 
Protozoa vary exceedingly in their body organization, morphological 
characteristics, behavior, habitat, etc., which necessitates a tax- 
onomic arrangement for proper consideration as set forth in detail 
in Chapters 8 to 44. 

Relationship of protozoology to other fields of 
biological science 

A brief consideration of the relationship of Protozoology to 
other fields of biology and its possible applications may not be 
out of place here. Since the Protozoa are single-celled animals 
manifesting the characteristics common to all living things, they 
have been studied by numerous investigators with a view to dis- 
covering the nature and mechanism of various phenomena, the 


sum-total of which is known collectively as life. Though the in- 
vestigators generally have been disappointed in the results, in- 
asmuch as the assumed simplicity of unicellular organisms has 
proved to be offset by the complexity of their cell-structure, never- 
theless discussion of any biological principles today must take into 
account the information obtained from studies of Protozoa. It is now 
commonly recognized that adequate information on various types 
of Protozoa is a prerequisite to a thorough comprehension of biology 
and to proper application of biological principles. 

Practically all students agree in assuming that the higher types of 
animals have been derived from organisms which existed in the re- 
mote past and which probably were somewhat similar to the primi- 
tive Protozoa of the present day. Since there is no sharp distinction 
between the Protozoa and the Protophyta or between the Protozoa 
and the Metazoa, and since there are intermediate forms between 
the major classes of the Protozoa themselves, progress in proto- 
zoology contributes toward the advancement of our knowledge on 
the probable steps by which living things in general evolved. 

Geneticists have undertaken studies on heredity and variation 
among Protozoa. "Unicellular animals," wrote Jennings (1909), 
"present all the problems of heredity and variation in miniature. 
The struggle for existence in a fauna of untold thousands showing 
as much variety of form and function as any higher group, works 
itself out, with ultimate survival of the fittest, in a few days under 
our eyes, in a finger bowl. For studying heredity and variation we 
get a generation a day, and we may keep unlimited numbers of 
pedigreed stock in a watch glass that can be placed under the micro- 
scope." Morphological and physiological variations are encountered 
commonly in all forms. Whether variation is due to germinal or 
environmental conditions, is often difficult to determine. Studies on 
conjugation in Paramecium by utilizing the mating types first noted 
by Sonneborn (1937, 1938) not only brought to light a wealth of 
important information regarding the genetics of Protozoa, but also 
are revealing a close insight concerning the relationship between the 
nuclear and cytoplasmic factors of heredity in the animal. 

Parasitic Protozoa are confined to one or more specific hosts. 
Through studies of the forms belonging to one and the same genus 
or species, the phylogenetic relation among the host animals may 
be established or verified. The mosquitoes belonging to the genera 
Culex and Anopheles, for instance, are known to transmit avian and 
human Plasmodium respectively. They are further infected by 
specific microsporidian parasites. For instance, Thelohania legeri 


has been found widely only in many species of anopheline mosqui- 
toes; T. opacita has, on the other hand, been found exclusively in 
culicine mosquitoes, although the larvae of the species belonging to 
these two genera live frequently in the same body of water (Kudo, 
1924, 1925). By observing certain intestinal Protozoa in some mon- 
keys, Hegner (1928) obtained evidence on the probable phylogenetic 
relationship between them and other higher mammals. The relation 
of various Protozoa of the wood-roach to those of the termite, as 
revealed by Cleveland and his associates (1934), gives further proof 
that the Blattidae and the Isoptera are closely related. 

Study of a particular group of parasitic Protozoa and their hosts 
may throw light on the geographic condition of the earth which 
existed in the remote past. The members of the genus Zelleriella are 
usually found in the colon of the frogs belonging to the family Lepto- 
dactylidae. Through an extensive study of these amphibians from 
South America and Australia, Metcalf (1920, 1929) found that the 
species of Zelleriella occurring in the frogs of the two continents are 
almost identical. He finds it more difficult to conceive of convergent 
or parallel evolution of both the hosts and the parasites, than to 
assume that there once existed between Patagonia and Australia a 
land connection over which frogs, containing Zelleriella, migrated. 

Experimental studies of large Protozoa have thrown light on the 
relation between the nucleus and the cytoplasm, and have furnished 
a basis for an understanding of regeneration in animals. In Protozoa 
we find various types of nuclear divisions ranging from a simple 
amitotic division to a complex process comparable in every detail 
with the typical metazoan mitosis. A part of our knowledge in 
cytology is based upon studies of Protozoa. 

Through the efforts of various investigators in the past fifty 
years, it has now become known that some 25 species of Protozoa 
occur in man. Entamoeba histolytica, Balantidium coli, and four 
species of Plasmodium, all of which are pathogenic to man, are 
widely distributed throughout the world. In certain restricted areas 
are found other pathogenic forms, such as Trypanosoma and Leish- 
mania. Since all parasitic Protozoa presumably have originated 
in free-living forms and since our knowledge of the morphology, 
physiology, and reproduction of the parasitic forms has largely been 
obtained in conjunction with the studies of the free-living organ- 
isms, a general knowledge of the entire phylum is necessary to under- 
stand these parasitic forms. 

Recent studies have further revealed that almost all domestic 
animals are hosts to numerous parasitic Protozoa, many of which 


are responsible for serious infectious diseases. Some of the forms 
found in domestic animals are morphologically indistinguishable 
from those occurring in man. Balantidium coli is considered as a 
parasite of swine, and man is its secondary host. Knowledge of 
protozoan parasites is useful to medical practitioners, just as it is 
essential to veterinarians inasmuch as certain diseases of animals, 
such as southern cattle fever, dourine, nagana, blackhead, coccidio- 
sis, etc., are caused by Protozoa. 

Sanitary betterment and improvement are fundamental re- 
quirements in the modern civilized world. One of man's necessities 
is safe drinking water. The majority of Protozoa live freely in various 
bodies of water and some of them are responsible, if present in suffi- 
ciently large numbers, for giving certain odors to the waters of 
reservoirs or ponds (p. 114). But these Protozoa which are occasion- 
ally harmful are relatively small in number compared with those 
which are beneficial to man. It is generally understood that bacteria 
live on various waste materials present in the polluted water, but 
that upon reaching a certain population, they would cease to multi- 
ply and would allow the excess organic substances to undergo de- 
composition. Numerous holozoic Protozoa, however, feed on the bac- 
teria and prevent them from reaching the saturation population. 
Protozoa thus seem to help indirectly in the purification of the water. 
Protozoology therefore must be considered as part of modern sani- 
tary science. 

Young fish feed extensively on small aquatic organisms, such as 
larvae of insects, small crustaceans, annelids, etc., all of which de- 
pend largely upon Protozoa and Protophyta as sources of food sup- 
ply. Thus the fish are indirectly dependent upon Protozoa as food 
material. On the other hand, there are numbers of Protozoa which 
live at the expense of fish. The Myxosporidia are almost exclusively 
parasites of fish and sometimes cause death to large numbers of com- 
mercially important fishes (Kudo, 1920) (p. 648). Success in fish- 
culture, therefore, requires among other things a thorough knowl- 
edge of Protozoa. 

Since Russel and Hutchinson (1909) suggested some forty years 
ago that Protozoa are probably a cause of limitation of the numbers, 
and therefore the activities of bacteria in the soil and thus tend to 
decrease the amount of nitrogen which is given to the soil by the 
nitrifying bacteria, several investigators have brought out the fact 
that in the soils of temperate climate various sarcodinans, flagellates 
and less frequently ciliates, are present and active throughout the 
year. The exact relation between specific Protozoa and bacteria in 


the soil is not yet clear in spite of the numerous experiments and 
observations. All soil investigators should be acquainted with the 
biology and taxonomy of free-living Protozoa. 

It is a matter of common knowledge that the silkworm and the 
honey bee suffer from microsporidian infections (p. 670). Sericulture 
in south-western Europe suffered great damages in the middle of 
the nineteenth century because of the "pebrine" disease, caused by 
the microsporidian, Nosema bombycis. During the first decade of 
the present century, another microsporidian, Nosema apis, was 
found to infect a large number of honey bees. Methods of control 
have been developed and put into practice so that these micro- 
sporidian infections are at present not serious, even though they still 
occur. On the other hand, other Microsporidia are now known to in- 
fect certain insects, such as mosquitoes and lepidopterous pests, 
which, when heavily infected, die sooner or later. Methods of de- 
struction of these insects by means of chemicals are more and more 
used, but attention should also be given to biological control of them 
by means of Protozoa and Protophyta. 

While the majority of Protozoa lack permanent skeletal structures 
and their fossil forms are little known, there are at least two large 
groups in the Sarcodina which possess conspicuous shells and which 
are found as fossils. They are Foraminifera and Radiolaria. From 
early palaeozoic era down to the present day, the carbonate of 
lime which makes up the skeletons of numerous Foraminifera has 
been left embedded in various rock strata. Although there is no dis- 
tinctive foraminiferan fauna characteristic of a given geologic pe- 
riod, there are certain peculiarities of fossil Foraminifera which dis- 
tinguish one formation from the other. From this fact one can un- 
derstand that knowledge of foraminiferous rocks is highly useful in 
checking up logs in well drilling. The skeletons of the Radiolaria are 
the main constituent of the ooze of littoral and deep-sea regions. 
They have been found abundantly in siliceous rocks of the palaeozoic 
and the mesozoic eras, and are also identified with the clays and 
other formations of the miocene period. Thus knowledge of these two 
orders of Sarcodina, at least, is essential for the student of geology 
and paleontology. 

The history of protozoology 

Aside from a comparatively small number of large forms, Protozoa 
are unobservable with the naked eye, so that one can easily under- 
stand why they were unknown prior to the invention of the micro- 
scope. Antony van Leeuwenhoek (1632-1723) is commonly recog- 


nized as the father of protozoology. Grinding lenses himself, 
Leeuwenhoek made more than 400 simple lenses, including one 
which, it is said, had a magnification of 270 times (Harting). Among 
the many things he discovered were various Protozoa. According 
to Dobell (1932), Leeuwenhoek saw in 1674 for the first time free- 
living fresh- water Protozoa. Between 1674 and 1716, he observed 
many Protozoa which he reported to the Royal Society of Lon- 
don and which, as Dobell interpreted, were Euglena ("green in 
the middle, and before and behind white"), Vorticella, Stylonychia, 
Carchesium, Volvox, Coleps, Kerona, Anthophysis, Elphidium, etc. 
Huygens gave in 1678 "unmistakable descriptions of Chilodon(-ella), 
Paramecium, Astasia and Vorticella, all found in infusions" (Dobell). 

Colpoda was seen by Buonanni (1691) and Harris (1696) rediscov- 
ered Euglena. In 1718 there appeared the first treatise on micro- 
scopic organisms, particularly of Protozoa, by Joblot who empha- 
sized the non-existence of abiogenesis by using boiled hay-infusions 
in which no Infusoria developed without exposure to the atmosphere. 
This experiment confirmed that of Redi who, some 40 years be- 
fore, had made his well-known experiments by excluding flies from 
meat. Joblot illustrated, according to Woodruff (1937), Paramecium, 
the slipper animalcule, with the first identifiable figure. Trembley 
(1744) studied division in some ciliates, including probably Para- 
mecium, which generic name was coined by Hill in 1752. Noctiluca 
was first described by Baker (1753). 

Rosel von Rosenhof (1755) observed an organism, which he called 
"der kleine Proteus," and also Vorticella, Stentor, and Volvox. The 
"Proteus" which Linnaeus named Volvox chaos (1758) and later re- 
named Chaos protheus (1767), cannot be identified with any of the 
known amoeboid organisms (Kudo, 1946). Wrisberg (1764) coined 
the term "Infusoria" (Dujardin; Woodruff). By using the juice of 
geranium, Ellis (1769) caused the extrusion of the "fins" (trichocysts) 
in Paramecium. Eichhorn (1783) observed the heliozoan, Actino- 
sphaerium, which now bears his name. O. F. Miiller described 
Ceratium a little later and published two works on the Infusoria 
(1773, 1786) although he included unavoidably some Metazoa and 
Protophyta in his monographs, some of his descriptions and figures 
of Ciliata were so well done that they are of value even at the present 
time. Lamarck (1816) named Folliculina. 

At the beginning of the nineteenth century the cylcosis in Para- 
mecium was brought to light by Gruithuisen. Goldfuss (1817) coined 
the term Protozoa, including in it the coelenterates. Nine years 
later there appeared d'Orbigny's systematic study of the Foramini- 


fera, which he considered "microscopical cephalopods." In 1828 
Ehrenberg began publishing his observations on Protozoa and in 
1838 he summarized his contributions in Die Infusionsthicrchen als 
vollkommene Organismen, in which he diagnosed genera and species 
so well that many of them still hold good. Ehrenberg excluded Rota- 
toria and Cercaria from Infusoria. Through the studies of Ehrenberg 
the number of known Protozoa increased greatly; he, however, pro- 
posed the term "Polygastricha," under which he placed Mastigo- 
phora, Rhizopoda, Ciliata, Suctoria, desmids, etc., since he believed 
that the food vacuoles present in them were stomachs. This hypothe- 
sis became immediately the center of controversy, which incidentally, 
together with the then-propounded cell theory and improvements in 
microscopy, stimulated researches on Protozoa. 

Dujardin (1835) took pains in studying the protoplasm of various 
Protozoa and found it alike in all. He named it sarcode. In 1841 he 
published an extensive monograph of various Protozoa which came 
under his observations. The term Rhizopoda was coined by this 
investigator. The commonly used term protoplasm was employed by 
Purkinje (1840) in the same sense as it is used today. The Protozoa 
was given a distinct definition by Siebold in 1845, as follows: "Die 
Thiere, in welchen die verschiedenen Systeme der Organe nicht 
scharf ausgeschieden sind, und deren unregelmassige Form und ein- 
fache Organization sich auf eine Zelle reduzieren lassen." Siebold 
subdivided Protozoa into Infusoria and Rhizopoda. The sharp differ- 
entiation of Protozoa as a group certainly inspired numerous micros- 
copists. As a result, several students brought forward various group 
names, such as Radiolaria (J. Muller, 1858), Ciliata (Perty, 1852), 
Flagellata (Cohn, 1853), Suctoria (Claparede and Lachmann, 1858), 
Heliozoa, Protista (Haeckel, 1862, 1866), Mastigophora (Diesing, 
1865), etc. Of Suctoria, Stein failed to see the real nature (1849), but 
his two monographs on Ciliata and Mastigophora (1854, 1859-1883) 
contain concise descriptions and excellent illustrations of numerous 
species. Haeckel who went a step further than Siebold by distinguish- 
ing between Protozoa and Metazoa, devoted 10 years to his study 
of Radiolaria, especially those of the Challenger collection, and de- 
scribed in his celebrated monographs more than 4000 species. 

In 1879 the first comprehensive monograph on the Protozoa of 
North America was put forward by Leidy under the title of Fresh- 
water Rhizopods of North America, which showed the wide distribu- 
tion of many known forms of Europe and revealed a number of new 
and interesting forms. This work was followed by Stokes' The Fresh- 
water Infusoria of the United States, which appeared in 1888. 


Butschli (1880-1889) established Sarcodina and made an excellent 
contribution to the taxonomy of the then-known species of Protozoa, 
which is still considered as one of the most important works on gen- 
eral protozoology. The painstaking researches by Maupas, on the 
conjugation of ciliates, corrected erroneous interpretation of the 
phenomenon observed by Balbiani some 30 years before and gave 
impetus to a renewed cytological study of Protozoa. The variety in 
form and structure of the protozoan nuclei became the subject of in- 
tensive studies by several cytologists. Weismann put into words the 
immortality of the Protozoa. Schaudinn contributed much toward 
the cytological and developmental studies of Protozoa. 

In the first year of the present century, Calkins in the United 
States and Dofiein in Germany wrote modern textbooks of protozo- 
ology dealing with the biology as well as the taxonomy. Jennings de- 
voted his time for nearly 40 years to the study of genetics of Pro- 
tozoa. Recent development of bacteria-free culture technique in cer- 
tain flagellates and ciliates, has brought to light important informa- 
tion regarding the nutritional requirements and metabolism of these 

Today the Protozoa are more and more intensively and exten- 
sively studied from both the biological and the parasitological sides, 
and important contributions appear continuously. Since all parasitic 
Protozoa appear to have originated in free-living forms, the com- 
prehension of the morphology, physiology, and development of the 
latter group is obviously fundamentally important for a thorough 
understanding of the former group. 

Compared with the advancement of our knowledge on free-living 
Protozoa, that on parasitic forms has been very slow. This is to be ex- 
pected, of course, since the vast majority of them are so minute that 
the discovery of their presence has been made possible only through 
improvements in the microscope and in technique. 

Here again Leeuwenhoek seems to have been the first to observe 
a parasitic protozoan, for he observed, according to Dobell (1932), in 
the fall of 1674, the oocysts of the coccidian Eimeria stiedae, in the 
contents of the gall bladder of an old rabbit; in 1681, Giardia intes- 
tinalis in his own diarrhceic stools; and in 1683, Opalina and Nycto- 
therus in the gut contents of frogs. The oral Trichomonas of man was 
observed by O. F. Miiller (1773) who named it Cercaria tenax (Do- 
bell, 1939). There is no record of anyone having seen Protozoa living 
in other organisms, until 1828, when Dufour's account of the grega- 
rine from the intestine of coleopterous insects appeared. Some ten 
years later, Hake rediscovered the oocysts of Eimeria stiedae. A 


flagellate was observed in the blood of salmon by Valentin in 1841, 
and the frog trypanosome was discovered by Gluge (1842) and 
Gruby (1843), the latter author creating the genus Trypanosoma 
for it. 

The gregarines were a little later given attention by Kolliker 
(1848) and Stein (1848). The year 1849 marks the first record of 
an amoeba being found in man, for Gros then observed Entamoeba 
gingivalis in the human mouth. Five years later, Davaine found 
in the stools of cholera patients two flagellates (Trichomonas and 
Chilomastix). Kloss in 1855 observed the coccidian, Klossia heli- 
cina, in the excretory organ of Helix; and Eimer (1870) made an ex- 
tensive study of Coccidia occurring in various animals. Balantidium 
coli was discovered by Malmsten in 1857. Lewis in 1870 observed 
Entamoeba coli in India, and Losch in 1875 found Entamoeba histo- 
lytica in Russia. During the early part of the last century, an epi- 
demic disease, pebrine, of the silkworm appeared in Italy and France, 
and a number of biologists became engaged in its investigation. Fore- 
most of all, Pasteur (1870) made an extensive report on the nature of 
the causative organism, now known as Nosema bombycis, and also on 
the method of control and prevention. Perhaps this is the first scien- 
tific study of a parasitic protozoan which resulted in an effective 
practical method of control of its infection. 

Lewis observed in 1878 an organism which is since known as 
Trypanosoma lewisi in the blood of rats. In 1879 Leuckart created 
the group Sporozoa, including in it the gregarines and coccidians. 
Other groups under Sporozoa were soon definitely designated. They 
are Myxosporidia (Butschli, 1881), Microsporidia and Sarcosporidia 
(Balbiani, 1882). 

Parasitic protozoology received a far-reaching stimulus when 
Laveran (November, 1880) discovered the microgamete formation 
("flagellation") of a malaria parasite in the human blood. Smith and 
Kilborne (1893) demonstrated that Babesia of the Texas fever of 
cattle in the southern United States was transmitted by the cattle 
tick from host to host, and thus revealed for the first time the close 
relationship which exists between an arthropod and a parasitic proto- 
zoan. Two years later Bruce discovered Trypanosoma brucei in the 
blood of domestic animals suffering from "nagana" disease in Africa 
and later (1897) demonstrated by experiments that the tsetse fly 
transmits the trypanosome. Studies of malaria organisms continued 
and several important contributions appeared. Golgi (1886, 1889) 
studied the schizogony and its relation to the occurrence of fever, 
and was able to distinguish the types of fever. MacCallum (1897) 


observed the microgamete formation in Haemoproteus of birds and 
suggested that the "flagella" observed by Laveran were micro- 
gametes of Plasmodium. In fact, he later observed the formation of 
the zygote through fusion of a microgamete and a macrogamete of 
Plasmodium falciparum. Almost at the same time, Schaudinn and 
Siedlecki (1897) showed that anisogamy results in the production of 
zygotes in Coccidia. The latter author published later further ob- 
servations on the life-cycle of Coccidia (1898, 1899). 

Ross (1898, 1898a) revealed the development of Plasmodium 
r dictum (P. praecox) in Culex fatigans and established the fact that 
the host birds become infected by this protozoan through the bites 
of the infected mosquitoes. Since that time, investigators too numer- 
ous to mention here (p. 600), studied the biology and development 
of the malarial organisms. Among the more recent findings is the 
exo-erythrocytic development, fuller information on which is now 
being sought. In 1902, Dutton found that the sleeping sickness in 
equatorial Africa was caused by an infection by Trypanosoma gam- 
biense. In 1903, Leishman and Donovan discovered simultaneously 
Leishmania donovani, the causative organism of "kala-azar" in 

Artificial cultivation of bacteria had contributed toward a very 
rapid advancement in bacteriology, and it was natural, as the num- 
ber of known parasitic Protozoa rapidly increased, that attempts to 
cultivate them in vitro should be made. Musgrave and Clegg (1904) 
cultivated, on bouillon-agar, small free-living amoebae from old 
faecal matter. In 1905 Novy and MacNeal cultivated successfully the 
trypanosome of birds in blood-agar medium, which remained free 
from bacterial contamination and in which the organisms underwent 
multiplication. Almost all species of Trypanosoma and Leishmania 
have since been cultivated in a similar manner. This serves for de- 
tection of a mild infection and also identification of the species in- 
volved. It was found, further, that the changes which these organ- 
isms underwent in the culture media were imitative of those that 
took place in the invertebrate host, thus contributing toward the 
life-cycle studies of them. 

During and since World War I, it became known that numer- 
ous intestinal Protozoa of man are widely present throughout the 
tropical, subtropical and temperate zones. Taxonomic, morphologi- 
cal and developmental studies on these forms have therefore ap- 
peared in an enormous number. Cutler (1918) seems to have suc- 
ceeded in cultivating Entamoeba histolytica, though his experiment 
was not repeated by others. Barret and Yarborough (1921) culti- 


vated Balantidium coli and Boeck (1921) cultivated Chilomastix 
mesnili. Boeck and Drbohlav (1925) succeeded in cultivating Enta- 
moeba histolytica, and their work was repeated and improved upon 
by many investigators. While the in-vitro cultivation has not thrown 
much light on metabolic activities of this and other parasitic 
amoebae, as no one of them would grow in culture without some 
other organisms, it has increased our knowledge on the biology of 
these parasites. 


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Calkins, G. N.: (1901) The Protozoa. Philadelphia. 

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les Infusoires et les Rhizopodes. Vol. 1. Geneva. 

Cleveland, L. R., Hall, S. R. and Sanders, E. P.: (1934) The 
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Cohn, F. J.: (1853) Beitrage zur Entwickelungsgeschichte der In- 
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Davaine, C. : (1854) Sur des animalcules infusoires, etc. C. R. Soc 
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and Reichenow, E.: (1929) Lehrbuch der Protozoenkunde. 

5 ed. Jena. 
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d'Orbigny, A. : (1826) Tableau methodique de la Classe des Cephal- 

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Organismen. Leipzig. 
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Psorospermien der Wirbelthiere. Wurzburg. 
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in the animalcula, etc. Phil. Trans., 59:138. 
Gluge, G. : (1842) Ueber ein eigenthumliches Entozoon im Blute 

des Frosches. Arch. Anat. Phys. wiss. Med., 148. 
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Golgi, C.: (1886) Sulla infezione malarica. Arch. Sci. Med., 10:109. 
— (1889) Sul ciclo evolutio dei parassiti malarici nella febbre 

terzana, etc. Ibid., 13:173. 
Gros, G.: (1849) Fragments d'helminthologie et de physiologie mi- 

croscopique. Bull. Soc. Imp. Nat. Moscou, 22:549. 
Gruby, D.: (1843) Recherches et observations sur une nouvelle 

espece d'hematozoaire, Trypanosoma sanguinis. C. R. Acad. Sc, 

Haeckel, E. H.: (1862) Betrachtungen ueber die Grenzen und Ver- 

wandschaft der Radiolarien und ueber die Systematik der 

Rhizopoden im Allgemeinen. Berlin. 

(1866) Generelle Morphologie der Organismen. Berlin. 

Hake, T. G.: (1839) A treatise on varicose capillaries, as constitut- 
ing the structure of carcinoma of the hepatic ducts, etc. Lon- 
Harris, J.: (1696) Some microscopical observations of vast num- 
bers of animalcula seen in water. Phil. Trans., 19:254. 
Hegner, R. : (1928) The evolutionary significance of the protozoan 

parasites of monkeys and man. Quart. Rev. Biol., 3:225. 
Hill, J. : (1752) An history of animals, etc. London. 
Hyman, Libbie H. : (1940) The invertebrates: Protozoa through 

Ctenophora. New York. 


Jennings, H. S. : (1909) Heredity and variation in the simplest or- 
ganisms. Am. Nat., 43:322. 

Joblot, L. : (1718) Descriptions et usages de plusieurs nouveaux mi- 
croscopes, etc. Paris. 

Kloss, H.: (1855) Ueber Parasiten in der Niere von Helix. Abh. 
Senckenb. Naturf. Ges., 1:189. 

Kolliker, A.: (1848) Beitrage zur Kenntnis niederer Thiere. 
Zeitschr. wiss. Zool., 1:34. 

Kudo, R. R. : (1920) Studies on Myxosporidia. Illinois Biol. Monogr. 
5:nos. 3, 4. 

(1924) Studies on Microsporidia parasitic in mosquitoes. 

III. Arch. Protist., 49:147. 
- (1925) IV. Centralbl. Bakt. I. Orig., 96:428. 

(1946) Pelomyxa carolinensis Wilson. I. Jour. Morph., 78: 


Laveran, A.: (1880) Note sur un nouveau parasite trouve dans le 

sang de plusieurs malades atteints de fievre palustre. Bull Acad. 

Med., 9:1235, 1268, 1346. 
(1880a) Un nouveau parasite trouve dans le sang des malades 

atteints de fievre palustre. Bull. Mem. Soc. Med. Hopit. Paris, 

Leidy, J.: (1879) Freshwater Rhizopods of North America. Rep. 

U. S. Geol. Survey, 12. 
Leishman, W. B.: (1903) On the possibility of the occurrence of 

trypanosomiasis in India. British Med. Jour., 1:1252. 
Leuckart, R. : (1879) Die Parasiten des Menschen. 2 ed. Leipzig. 
Lewis, T. R. (1870) A report on the microscopic objects found in 

cholera evacuations, etc. Ann. Rep. San. Comm. Gov. India 

(1869) 6:126. 
(1878) The microscopic organisms found in the blood of man 

and animals, etc. Ibid. (1877) 14:157. 
Linnaeus, C.: (1758) Systema Naturae. 10 ed. 1:820. 

— ■ (1767) Systema Naturae. 12 ed. 1:1324. 
Losch, F. : (1875) Massenhafte Entwickelung von Amoben im Dick- 

darm. Arch. path. Anat., 65:196. 
Lwoff, A.: (1951) Biochemistry and physiology of Protozoa. New 

MacCallum, W. G.: (1897) On the flagellated form of the malarial 

parasite. Lancet, 2:1240. 
Malmsten, P. H.: (1857) Infusorien als Intestinal-Thiere beim 

Menschen. Arch. path. Anat., 12:302. 
Metcalf, M. M.: (1920) Upon an important method of studying 

problems of relationship and of geographical distribution. Proc. 

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Musgrave, W. E. and Clegg, M. T. : (1904) Amebas: their cultiva- 
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Manila, no. 18:1. 


Novy, F. G. and MacNeal, W. J.: (1905) On the trypanosomes of 

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Rosel von Rosenhof, A. J.: (1755) Der kleine Proteus. Der 

Monat.-herausgeg. Insect. -Belust., 3:622. 
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grey mosquitoes. Gov. Print. Calcutta. 
(1898a) Preliminary report on the infection of birds with 

Proteosoma by the bites of mosquitoes. Ibid. 
Russell, E. J. and Hutchinson, H. B.: (1909) The effect of partial 

sterilization of soil on the production of plant food. J. Agr. Sc, 

Schaudinn, F. and Siedlecki, M.: (1897) Beitrage zur Kenntnis 

der Coccidien. Verhandl. deut. zool. Ges., p. 192. 
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turgeschichte der Wiirmer, etc. Arch. Naturg., 11:256. 
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cidie de la seiche. Ann. Inst. Pasteur, 12:799. 

Etude cytologique et cycle evolutif de Adelea ovata 

Schneider. Ibid., 13:169. 

Smith, T. and Kilborne, F. L. : (1893) Investigations into the na- 
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Phil. Soc, 79:411. 

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ungsgeschichte untersucht. Leipzig. 

(1859-83) Der Organismus der Infusionsthiere. Leipzig. 

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Trembley, A.: (1744) Observations upon several newly discovered 
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Valentin: (1841) Ueber ein Entozoon im Blute von Salmo fario. 
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(1939) Some pioneers in microscopy, with special reference 

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Satura. Gottingen. 

Chapter 2 

WITH regard to their habitats, the Protozoa may be divided 
into free-living forms and those living on or in other organisms. 
Mastigophora, Sarcodina, Ciliata, and Suctoria include both free- 
living and parasitic Protozoa, but Sporozoa are exclusively parasi- 

Free-living Protozoa 

The vegetative or trophic stages of free-living Protozoa have been 
found in every type of fresh and salt water, soil and decaying or- 
ganic matter. Even in the circumpolar regions or at extremely high 
altitudes, certain protozoa occur at times in fairly large numbers. 
The factors, which influence their distribution in a given body of wa- 
ter, are temperature, light, chemical composition, acidity, kind and 
amount of food, and degree of adaptability of the individual proto- 
zoans to various environmental changes. Their early appearance as 
living organisms, their adaptability to various habitats, and their ca- 
pacity to remain viable in the encysted condition, probably account 
for the wide distribution of the Protozoa throughout the world. The 
common free-living amoebae, numerous testaceans and others, to 
mention a few, of fresh waters, have been observed in innumerable 
places of the world. 

Temperature. The majority of Protozoa are able to live only 
within a small range of temperature variation, although in the en- 
cysted state they can withstand a far greater temperature fluctua- 
tion. The lower limit of the temperature is marked by the freezing of 
the protoplasm, and the upper limit by the destructive chemical 
change within the body protoplasm. The temperature toleration 
seems to vary among different species of Protozoa; and even in the 
same species under different conditions. For example, Chalkley 
(1930) placed Paramecium caudatum in 4 culture media (balanced 
saline, saline with potassium excess, saline with calcium excess, and 
saline with sodium excess), all with pH from 5.8 or 6 to 8.4 or 8.6, at 
40°C. for 2-16 minutes and found that (1) the resistance varies with 
the hydrogen-ion concentration, maxima appearing in the alkaline 
and acid ranges, and a minimum at or near about 7.0; (2) in a bal- 
anced saline, and in saline with an excess of sodium or potassium, the 
alkaline maximum is the higher, while in saline with an excess of 
calcium, the acid maximum is the higher; (3) in general, acidity de- 
creases and alkalinity increases resistance; and (4) between pH 6.6 



and 7.6, excess of potassium decreases resistance and excess of cal- 
cium increases resistance. Glaser and Coria (1933) cultivated Para- 
mecium caudatum on dead yeast free from living organisms at 
20-28°C. (optimum 25°C.) and noted that at 30°C. the organisms 
were killed. Doudoroff (1936), on the other hand, found that in 
P. multimicronucleatum its resistance to raised temperature was low 
in the presence of food, but rose to a maximum when the food was 
exhausted, and there was no appreciable difference in the resistance 
between single and conjugating individuals. 

The thermal waters of hot springs have been known to contain liv- 
ing organisms including Protozoa. Glaser and Coria' (1935) obtained 
from the thermal springs, of Virginia, several species of Mastigoph- 
ora, Ciliata, and an amoeba which were living in the water, the tem- 
perature of which was 34-36°C, but did not notice any protozoan in 
the water which showed 39-41°C. Uyemura (1936, 1937) made a 
series of studies on Protozoa living in various thermal waters of Ja- 
pan, and reported that many species lived at unexpectedly high 
temperatures. Some of the Protozoa observed and the temperatures 
of the water in which they were found are as follows: Amoeba sp., 
Vahlkampfia Umax, A. radiosa, 30-51°C; Amoeba verrucosa, Chilo- 
donella sp., Lionotus fasciola, Paramecium caudatum, 36-40°C; 
Oxytricha fallax, 30-56°C. 

Under experimental conditions, it has been shown repeatedly that 
many protozoans become accustomed to a very high temperature if 
the change be made gradually. Dallinger (1887) showed a long time 
ago that Tetramitus rostratus and two other species of flagellates 
became gradually acclimatized up to 70°C. in several years. In na- 
ture, however, the thermal death point of most of the free-living 
Protozoa appears to lie between 36° and 40°C. and the optimum 
temperature, between 16° and 25°C. 

On the other hand, the low temperature seems to be less detri- 
mental to Protozoa than the higher one. Many protozoans have 
been found to live in water under ice, and several haematochrome- 
bearing Phytomastigina undergo vigorous multiplication on snow in 
high altitudes, producing the so-called "red snow." Klebs (1893) sub- 
jected the trophozoites of Euglena to repeated freezing without ap- 
parent injury and Jahn (1933) found no harmful effect when Euglena 
cultures were kept without freezing at — 0.2°C. for one hour, but 
when kept at — 4°C. for one hour the majority were killed. Gay lord 
(1908) exposed Trypanosoma gambiense to liquid air for 20 minutes 
without apparent injury, but the organisms were killed after 40 min- 
utes' immersion, 


Kiihne (1864) observed that Amoeba and Actinophrys suffered no 
ill effects when kept at 0°C. for several hours as long as the culture 
medium did not freeze, but were killed when the latter froze. Molisch 
(1897) likewise noticed that Amoeba dies as soon as the ice forms in 
its interior or immediate vicinity. Chambers and Hale (1932) dem- 
onstrated that internal freezing could be induced in an amoeba by 
inserting an ice-tipped pipette at — 0.6°C, the ice spreading in the 
form of fine featherly crystals from the point touched by the pipette. 
They found that the internal freezing kills the amoebae, although 
if the ice is prevented from forming, a temperature as low as — 5°C. 
brings about no visible damage to the organism. At 0°C, Deschiens 
(1934) found the trophozoites of Entamoeba histolytica remained 
alive, though immobile, for 56 hours, but were destroyed in a short 
time when the medium froze at — 5°C. 

According to Greeley (1902), when Stentor coeruleus was slowly 
subjected to low temperatures, the cilia kept on beating at 0°C. for 
1-3 hours, then cilia and gullet were absorbed, the ectoplasm was 
thrown off, and the body became spherical. When the temperature 
was raised, this spherical body is said to have undergone a reverse 
process and resumed its normal activity. If the lowering of tempera- 
ture is rapid and the medium becomes solidly frozen, Stentor per- 
ishes. Efimoff (1924) observed that Paramecium multiplied once in 
about 13 days at 0°C, withstood freezing at — 1°C. for 30 minutes 
but died when kept for 50-60 minutes at the same temperature. He 
further stated that Paramecium caudatum, Colpidium colpoda, and 
Spirostomum ambiguum, perished in less than 30 minutes, when ex- 
posed below — 4°C, and that quick and short cooling (not lower than 
— 9°C.) produced no injury, but if it is prolonged, Paramecium be- 
came spherical and swollen to 4-5 times normal size, while Colpid- 
ium and Spirostomum shrunk. Wolfson (1935) studied Paramecium 
sp. in gradually descending subzero-temperature, and observed that 
as the temperature decreases the organism often swims backward, 
its bodily movements cease at — 14.2°C, but the cilia continue to 
beat for some time. While Paramecium recover completely from a 
momentary exposure to — 16°C, long cooling at this temperature 
brings about degeneration. When the water in which the organisms 
are kept freezes, no survival was noted. Plasmodium knowlcsi and 
P. inui in the blood of Macacus rhesus remain viable, according to 
Coggeshall (1939), for as long as 70 days at — 76°C, if frozen and 
1 hawed rapidly. Low temperature on Protozoa (Luyet and Gehenio, 

Light. In the Phytomastigina which include chromatophore-bear- 


ing flagellates, the sun light is essential to photosynthesis (p. 107). The 
sun light further plays an important role in those protozoans which 
are dependent upon chromatophore-possessing organisms as chief 
source of food supply. Hence the light is another factor concerned 
with the distribution of free-living Protozoa. 

Chemical composition of water. The chemical nature of the water 
is another important factor which influences the very existence of 
Protozoa in a given body of water. Protozoa differ from one another 
in morphological as well as physiological characteristics. Individual 
protozoan species requires a certain chemical composition of the wa- 
ter in which it can be cultivated under experimental conditions, al- 
though this may be more or less variable among different forms 
(Needham et al, 1937). 

In their "biological analysis of water" Kolkwitz and Marsson 
(1908, 1909) distinguished four types of habitats for many aquatic 
plant, and a few animal, organisms, which were based upon the kind 
and amount of inorganic and organic matter and amount of oxygen 
present in the water: namely, katharobic, oligosaprobic, mesosapro- 
bic, and polysaprobic. Katharobic protozoans are those which live in 
mountain springs, brooks, or ponds, the water of which is rich in 
oxygen, but free from organic matter. Oligosaprobic forms are those 
that inhabit waters which are rich in mineral matter, but in which 
no purification processes are taking place. Many Phytomastigina, 
various testaceans and many ciliates, such as Frontonia, Lacrymaria, 
Oxytricha, Stylonychia, Vorticella, etc. inhabit such waters. Meso- 
saprobic protozoans live in waters in which active oxidation and de- 
composition of organic matter are taking place. The majority of 
freshwater protozoans belong to this group: namely, numerous 
Phytomastigina, Heliozoa, Zoomastigina, and all orders of Ciliata. 
Finally polysaprobic forms are capable of living in waters which, 
because of dominance of reduction and cleavage processes of organic 
matter, contain at most a very small amount of oxygen and are rich 
in carbonic acid gas and nitrogenous decomposition products. The 
black bottom slime contains usually an abundance of ferrous sul- 
phide and other sulphurous substances. Lauterborn (1901) called this 
sapropelic. Examples of polysaprobic protozoans are Pelomyxa 
palustris, Euglypha alveolata, Pamphagus armatus, Mastigamoeba, 
Trepomonas agilis, Hexamita inflata, Rhynchomonas nasuta, Hetero- 
nema acus, Bodo, Cercomonas, Dactylochlamys, Ctenostomata, etc. 
The so-called "sewage organisms" abound in such habitat (Lackey, 

Certain free-living Protozoa which inhabit waters rich in decom- 


posing organic matter are frequently found in the faecal matter of 
various animals. Their cysts either pass through the alimentary 
canal of the animal unharmed or are introduced after the faeces are 
voided, and undergo development and multiplication in the faecal 
infusion. Such forms are collectively called coprozoic Protozoa. The 
coprozoic protozoans grow easily in suspension of old faecal matter 
which is rich in decomposed organic matter and thus show a strik- 
ingly strong capacity of adapting themselves to conditions different 
from those of the water in which they normally live. Some of the 
Protozoa which have been referred to as coprozoic and which are 
mentioned in the present work are, as follows: Scytomonas pusilla, 
Rhynchomonas nasuta, Cercomonas longicauda, C. crassicauda, Tre- 
pomonas agilis, Naegleria gruberi, Acanthamoeba hyalina, Chlamy- 
dophrys stercorea and Tillina magna. 

As a rule, the presence of sodium chloride in the sea water prevents 
the occurrence of numerous species of fresh-water inhabitants. Cer- 
tain species, however, have been known to live in both fresh and 
brackish or salt water. Among the species mentioned in the present 
work, the following species have been reported to occur in both fresh 
and salt waters: Mastigophora: Amphidinium lacustre, Cerat- 
ium hirundinella; Sarcodina: Lieberkiihnia wagneri; Ciliata: Meso- 
dinium pidex, Prorodon discolor, Lacrymaria olor, Amphileptus 
claparedei, Lionotus fasciola, Nassula aurea, Trochilioides recta, 
Chilodonella cucullulus, Trimyema compressum, Paramecium cal- 
kinsi, Colpidium campylum, Platynematum sociale, Cinetochilum 
margaritaceum, Pleuronema coronatum, Caenomorpha medusula, 
Spirostomum minus, S. teres, Climacostomum virens, and Thuricola 
folliculata; Sxictoria, : Metacineta mystacina, Endosphaera engelmanni. 

It seems probable that many other protozoans are able to live 
in both fresh and salt water, judging from the observations such 
as that made by Finley (1930) who subjected some fifty species of 
freshwater Protozoa of Wisconsin to various concentrations of sea 
water, either by direct transfer or by gradual addition of the sea 
water. He found that Bodo uncinatus, Uronema marinum, Pleuron- 
ema jaculans and Colpoda aspera are able to live and reproduce 
even when directly transferred to sea water, that Amoeba verrucosa, 
Euglena, Phacus, Monas, Cyclidium, Euplotes, Lionotus, Para- 
mecium, Stylonychia, etc., tolerate only a low salinity when directly 
transferred, but, if the salinity is gradually increased, they live in 
100 per cent sea water, and that Arcella, Cyphoderia, Aspidisca, Ble- 
pharisma, Colpoda cucullus, Halteria, etc. could not tolerate 10 per 
cent sea water even when the change was gradual. Finley noted no 


morphological changes in the experimental protozoans which might 
be attributed to the presence of the salt in the water, except Amoeba 
verrucosa, in which certain structural and physiological changes were 
observed as follows: as the salinity increased, the pulsation of the 
contractile vacuole became slower. The body activity continued up 
to 44 per cent sea water and the vacuole pulsated only once in 40 
minutes, and after systole, it did not reappear for 10-15 minutes. 
The organism became less active above this concentration and in 
84 per cent sea water the vacuole disappeared, but there was still a 
tendency to form the characteristic ridges, even in 91 per cent sea 
water, in which the organism was less fan-shaped and the cytoplasm 
seemed to be more viscous. Yocom (1934) found that Ewplotes pa- 
tella was able to live normally and multiply up to 66 per cent of 
sea water; above that concentration no division was noticed, though 
the organism lived for a few days in up to 100 per cent salt water, 
and Paramecium caudatum and Spirostomum ambiguum were less 
adaptive to salt water, rarely living in 60 per cent sea water. Frisch 
(1939) found that no freshwater Protozoa lived above 40 per cent 
sea water and that Paramecium caudatum and P. multimicronucle- 
atum died in 33-52 per cent sea water. Hardin (1942) reports that 
Oikomonas termo will grow when transferred directly to a glycerol- 
peptone culture medium, in up to 45 per cent sea water, and cultures 
contaminated with bacteria and growing in a dilute glycerol-peptone 
medium will grow in 100 per cent sea water. 

Hydrogen-ion concentration. Closely related to the chemical com- 
position is the hydrogen-ion concentration (pH) of the water. Some 
Protozoa appear to tolerate a wide range of pH. The interesting pro- 
teomyxan, Leptomyxa reticulata, occurs in soil ranging in pH 4.3 to 
7.8, and grows very well in non-nutrient agar between pH 4.2 and 
8.7, provided a suitable bacterial strain is supplied as food (Singh, 
1948) ; and according to Loefer and Guido (1950), a strain of Euglena 
gracilis (var. bacillaris) grows between pH 3.2 and 8.3. However, the 
majority of Protozoa seem to prefer a certain range of pH for the 
maximum metabolic activity. 

The hydrogen-ion concentration of freshwater bodies varies a great 
deal between highly acid bog waters in which various testaceans 
may frequently be present, to highly alkaline water in which such 
forms as Acanthocystis, Hyalobryon, etc., occur. In standing deep 
fresh water, the bottom region is often acid because of the decom- 
posing organic matter, while the surface water is less acid or slightly 
alkaline due to the photosynthesis of green plants which utilize car- 
bon dioxide. In some cases different pH may bring about morpho- 



logical differences. For example, in bacteria-free cultures of Para- 
mecium bursaria in a tryptone medium, Loefer (1938) found that at 
pH 7.6-8.0 the length averaged 86 or 87/x, but at 6.0-6.3 the length 
was about 129/z. The greatest variation took place at pH 4.6 in which 
no growth occurred. The shortest animals at the acid and alkaline 
extremes of growth were the widest, while the narrowest forms 
(about 44m wide) were found in culture at pH 5.7-7.4. Many workers 
have made observations on the pH range of the water or medium 
in which certain protozoans live, grow, and multiply, some of which 
data are collected in Table 1 . 

Table 1 . — Protozoa and hydrogen-ion concentration 


pH range of 
medium in which 



growth occurs 

A. In bacteria-free cultures 

Euglena gracilis 










. — 



E. deses 







E. piscijormis 







E. viridis 




Chilomonas Paramecium 



Mast and Pace 




Chlorogonium euchlorum 




C. elongatum 




C. teragamum 




Colpidmm campylum 




Glaucoma scintillans 




G. ficara 




Tetrahymena pyriformis 




T. vorax 




Paramecium bursaria 




B. In cultures containing bacteria 

Carteria obtusa 




Trichomonas vaginalis 



Bland et al. 

Actinosphaerium eichhorni 




Acanthocystis aculeata 

7 . 4 or above 8 . 1 


Paramecium caudatum 










P. aurelia 






Table 1. — Continued 


pH range of 
medium in whicl 



growth occurs 








P. multim icronucleatum 







P. trichium 




P. bursaria 




P. poly car yum 




P. calkinsi 




P. woodruffi 




Colpidium sp. 




Colpoda cucullus 




Holophyra sp. 




Plagiopyla sp. 




Amphileptus sp. 




Spirostomvm ambiguum 




S. sp. 




Stentor coeruleus 




Blepharisma undulans 




Gastrostyla sp. 




Stylonychia pustulata 




Food. The kind and amount of food available in a given body 
of water also controls the distribution of Protozoa. The food is 
ordinarily one of the deciding factors of the number of Protozoa 
in a natural habitat. Species of Paramecium and many other holo- 
zoic protozoans cannot live in waters in which bacteria or minute 
protozoans do not occur. If other conditions are favorable, then the 
greater the number of food bacteria, the greater the number of 
protozoa. Noland (1925) studied more than 65 species of fresh-water 
ciliates with respect to various factors and came to the conclusion 
that the nature and amount of available food has more to do with 
the distribution of these organisms than any other one factor. Di- 
dinium nasutum feeds almost exclusively on paramecia; therefore, it 
cannot live in the absence of the latter ciliate. As a rule, euryphagous 
Protozoa which feed on a variety of food organisms are widely dis- 
tributed, while stenophagous forms that feed on a few species of food 
organisms are limited in their distribution. 

In nature, Protozoa live in association with diverse organisms. 
The interrelationships which exist among them are not understood 
in most cases. For example, the relationship between Entamoeba 
histolytica and certain bacteria in successful in-vitro cultivation has 


not yet been comprehended. Certain strains of bacteria were found 
by Hardin (1944) to be toxic for Paramecium multimicronucleatum, 
but if Oikomonas termo was present in the culture, the ciliate was 
maintained indefinitely. This worker suggested that the flagellate 
may be able to "detoxify" the metabolic products produced by the 
bacteria. Food relation in ciliates (Faure-Fremiet, 1950, 1951a). 

The adaptability of Protozoa to varied environmental conditions 
influences their distribution. The degree of adaptability varies a 
great deal, not only among different species, but also among the 
individuals of the same species. Stentor coeruleus which grows ordi- 
narily under nearly anaerobic conditions, is obviously not influenced 
by alkalinity, pH, temperature or free carbon dioxide in the water 
(Sprugel, 1951). 

Some protozoans inhabit soil of various types and localities. Un- 
der ordinary circumstances, they occur near the surface, their maxi- 
mum abundance being found at a depth of about 10-12 cm. (Sandon, 
1927). It is said that a very few protozoans occur in the subsoil. 
Here also one notices a very wide geographical distribution of ap- 
parently one and the same species. For example, Sandon found 
Amoeba proteus in samples of soil collected from Greenland, Tristan 
da Cunha, Gough Island, England, Mauritius, Africa, India, and 
Argentina. This amoeba is known to occur in various parts of North 
America, Europe, Japan, and Australia. The majority of Testacea 
inhabit moist soil in abundance. Sandon observed Trinema enchelys 
in the soils of Spitzbergen, Greenland, England, Japan, Australia, St. 
Helena, Barbados, Mauritius, Africa, and Argentina. 

Parasitic Protozoa 

Some Protozoa belonging to all groups live on or in other organ- 
isms. The Sporozoa are made up exclusively of parasites. The rela- 
tionships between the host and the protozoan differ in various ways, 
which make the basis for distinguishing the associations into three 
types as follows: commensalism, symbiosis, and parasitism. 

Commensalism is an association in which an organism, the com- 
mensal, is benefited, while the host is neither injured nor benefited. 
Depending upon the location of the commensal in the host body, 
the term ectocommensalism or endocommensalism is used. Ecto- 
commensalism is often represented by Protozoa which may attach 
themselves to any aquatic animals that inhabit the same bod}' of 
water, as shown by various species of Chonotricha, Peritricha, and 
Suctoria. In other cases, there is a definite relationship between the 
commensal and the host. For example, Kerona polyporum is found 


on various species of Hydra, and many ciliates placed in Thigmo- 
tricha (p. 774) are inseparably associated with certain species of 

Endocommensalism is often difficult to distinguish from endo- 
parasitism, since the effect of the presence of a commensal upon the 
host cannot be easily understood. On the whole, the protozoans 
which live in the lumen of the alimentary canal may be looked upon 
as endocommensals. These protozoans undoubtedly use part of the 
food material which could be used by the host, but they do not in- 
vade the host tissue. As examples of endocommensals may be men- 
tioned: Endamoeba blattae, Lophomonas blattarum, L. striata, 
Nyctotherus ovalis, etc., of the cockroach; Entamoeba coli, Iodamoeba 
biitschlii, Endolimax nana, Dientamoeba fragilis, Chilomastix mes- 
nili, etc., of the human intestine; numerous species of Protociliata of 
Anura, etc. Because of the difficulties mentioned above, the term 
parasitic Protozoa, in its broad sense, includes the commenals also. 

Symbiosis on the other hand is an association of two species of 
organisms, which is of mutual benefit. The cryptomonads belonging 
to Chrysidella ("Zooxanthellae") containing yellow or brown chrom- 
atophores, which live in Foraminifera and Radiolaria, and certain 
algae belonging to Chlorella ("Zoochlorellae") containing green 
chromatophores, which occur in some freshwater protozoans, such as 
Paramecium bursaria, Stentor amethystinus, etc., are looked upon 
as holding symbiotic relationship with the respective protozoan host. 
Several species of the highly interesting Hypermastigina, which are 
present commonly and abundantly in various species of termites and 
the woodroach Cryptocercus, have been demonstrated by Cleveland 
to digest the cellulose material which makes up the bulk of wood- 
chips the host insects take in and to transform it into glycogenous 
substances that are used partly by the host insects. If deprived of 
these flagellates by being subjected to oxygen under pressure or to 
a high temperature, the termites die, even though the intestine is 
filled with wood-chips. If removed from the gut of the termite, the 
flagellates perish (Cleveland, 1924, 1925). Recently, Cleveland 
(1949-1950c) found that the molting hormone produced by Crypto- 
cercus induces sexual reproduction in several flagellates inhabiting 
its hind-gut (p. 185). Thus the association here may be said to be an 
absolute symbiosis. 

Parasitism is an association in which one organism (the parasite) 
lives at the expense of the other (the host) . Here also ectoparasitism 
and endoparasitism occur, although the former is not commonly 
found. Hydramoeba hydroxena (p. 464) feeds on the body cells of 


Hydra which, according to Reynolds and Looper (1928), die on an 
average in 6.8 days as a result of the infection and the amoebae dis- 
appear in from 4 to 10 days if removed from a host Hydra. Costia 
necatrix (p. 372) often occurs in an enormous number, attached to 
various freshwater fishes especially in an aquarium, by piercing 
through the epidermal cells and appears to disturb the normal func- 
tions of the host tissue. Ichthyophthirius multifiliis (p. 709), another 
ectoparasite of freshwater and marine fishes, goes further by com- 
pletely burying themselves in the epidermis and feeds on the host's 
tissue cells and, not infrequently, contributes toward the cause of the 
death of the host fishes. 

The endoparasites absorb by osmosis the vital body fluid, feed on 
the host cells or cell-fragments by pseudopodia or cytostome, or 
enter the host tissues or cells themselves, living on the cytoplasm or 
in some cases on the nucleus. Consequently they bring about abnor- 
mal or pathological conditions upon the host which often succumbs 
to the infection. Endoparasitic Protozoa of man are Entamoeba 
histolytica, Balantidium coli, species of Plasmodium and Leishmania, 
Trypanosoma gambiense, etc. The Sporozoa, as was stated before, are 
without exception coelozoic, histozoic, or cytozoic parasites. 

Because of their modes of living, the endoparasitic Protozoa cause 
certain morphological changes in the cells, tissues, or organs of the 
host. The active growth of Entamoeba histolytica in the glands of the 
colon of the victim, produces first slightly raised nodules which de- 
velop into abscesses and the ulcers formed by the rupture of ab- 
scesses, may reach 2 cm. or more in diameter, completely destroying 
the tissues of the colon wall. Similar pathological changes may also 
occur in the case of infection by Balantidium coli. In Leishmania 
donovani, the victim shows an increase in number of the large macro- 
phages and mononuclears and also an extreme enlargement of the 
spleen. Trypanosoma cruzi brings about the degeneration of the in- 
fected host cells and an abundance of leucocytes in the infected 
tissues, followed by an increase of fibrous tissue. T. gambiense, the 
causative organism of African sleeping sickness, causes enlargement 
of lymphatic glands and spleen, followed by changes in meninges 
and an increase of cerebro-spinal fluid. Its most characteristic 
changes are the thickening of the arterial coat and the round-celled 
infiltration around the blood vessels of the central nervous system. 

Malarial infection is invariably accompanied by an enormous 
enlargement of the spleen ("spleen index"); the blood becomes 
watery; the erythrocytes decrease in number; the leucocytes, sub- 
normal; but mononuclear cells increase in number; pigment granules 



which are set free in the blood plasma at the time of merozoite- 
liberation are engulfed by leucocytes; and enlarged spleen contains 
large amount of pigments which are lodged in leucocytes and endo- 
thelial cells. In Plasmodium falciparum, the blood capillaries of 
brain, spleen and other viscera may completely be blocked by in- 
fected erythrocytes. 

In Myxosporidia which are either histozoic or coelozoic parasites 
of fishes, the tissue cells that are in direct contact with highly en- 
larging parasites, undergo various morphological changes. For exam- 


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Fig. 1. Histological changes in host fish caused by myxosporidian in- 
fection, X1920 (Kudo), a, portion of a cyst of Myxobolus intestinalis, sur- 
rounded by peri-intestinal muscle of the black crappie; b, part of a cyst 
of Thelohanellus notatus, enveloped by the connective tissue of the blunt- 
nosed minnow. 

pie, the circular muscle fibers of the small iniestine of Pomoxis 
sparoides, which surround Myxobolus intestinalis, a myxosporidian, 
become modified a great deal and turn about 90° from the original 
direction, due undoubtedly to the stimulation exercised by the 
myxosporidian parasite (Fig. 1, a). In the case of another myxo- 
sporidian, Thelohanellus notatus, the connective tissue cells of the 
host fish surrounding the protozoan body, transform themselves into 
"epithelial cells" (Fig. 1, b), a state comparable to the formation of 
the ciliated epithelium from a layer of fibroblasts lining a cyst 
formed around a piece of ovary inplanted into the adductor muscle 
of Pecten as observed by Drew (1911), 


Practically all Microsporidia are cytozoic, and the infected cells 
become hypertrophied enormously, producing in one genus the so- 
called Glugea cysts (Figs. 287, 290). In many cases, the hypertrophy 
of the nucleus of the infected cell is far more conspicuous than that 
of the cytoplasm (Figs. 287, 291) (Kudo, 1924). 

When the gonads are parasitized heavify, the germ cells of the 
host animal often do not develop, thus resulting in parasitic castra- 
tion. For example, the ciliate, Orchitophrya steUarum, a parasite in 
the male reproductive organ of Asterias rubens, was found by Vevers 
(1951) to break down completely all germinal tissues of the testes in 
the majority of the host starfish. In other cases, the protozoan does 
not invade the gonads, but there is no development of the germ cells. 
The microsporidian, Nose ma apis, attacks solely the gut epithelium 
of the honey bee, but the ovary of an infected queen bee degenerates 
to varying degrees (Hassanein, 1951). Still in other instances, the 
Protozoa invade developing ova of the host, but do not hinder their 
development, though the parasites multiply, as in Nosema bombycis 
in the silkworm (Stempell, 1909) and Babesia bigemina in the cattle 
tick (Dennis, 1932). 

For the great majority of parasitic Protozoa, there exists a de- 
finite host-parasite relationship and animals other than the specific 
hosts possess a natural immunity against an infection by a particular 
parasitic protozoan. Immunity involved in diseases caused by Pro- 
tozoa has been most intensively studied on haemozoic forms, es- 
pecially Plasmodium and Trypanosoma, since they are the causative 
organisms of important diseases. Development of these organisms 
in hosts depends on various factors such as the species and strains 
of the parasites, the species and strains of vectors, and immunity of 
the host. Boyd and co-workers showed that reinoculation of persons 
who have recovered from an infection with Plasmodium vivax or P. 
falciparum with the same strain of the parasites, will not result in a 
second clinical attack, because of the development of homologous 
immunity, but with a different strain of the same species or different 
species, a definite clinical attack occurs, thus there being no hetero- 
logous tolerance. The homologous immunity was found to continue 
for at least three years and in one case for about seven years in P. 
vivax, and for at least four months in P. falciparum after apparent 
eradication of the infection. In the case of leishmaniasis, recovery 
from a natural or induced infection apparently develops a lasting 
immunity against reinfection with the same species of Leishmania. 

It has been shown that in infections with avian, monkey and hu- 
man Plasmodium or Trypanosoma hwisi 1 a considerable number of 


the parasites are destroyed during the developmental phase of the 
infection and that after a variable length of time, resistance to the 
parasites often develops in the host, as the parasites disappear from 
the peripheral blood and symptoms subside, though the host still 
harbors the organisms. In malarious countries, the adults and chil- 
dren show usually a low and a high rate of malaria infection respect- 
ively, but the latter frequently do not show symptoms of infection, 
even though the parasites are detectable in the blood. Apparently 
repeated infection produces tolerance which can keep, as long as the 
host remains healthy, the parasites under control. There seems to be 
also racial difference in the degree of immunity against Plasmodium 
and Trypanosoma. 

As to the mechanism of immunity, the destruction of the parasites 
by phagocytosis of the endothelial cells of the spleen, bone marrow 
and liver and continued regenerative process to replace the de- 
stroyed blood cells, are the two important phases in the cellular de- 
fense mechanism. Besides, there are indications that humoral de- 
fense mechanism through the production of antibodies is in active 
operation in infections by Plasmodium knowlesi and trypanosomes 
(Taliaferro, 1926; Maegraith, 1948; Culbertson, 1951). Immunity 
(Taliaferro, 1941). 

With regard to the origin of parasitic Protozoa, it is generally 
agreed among biologists that the parasite in general evolved from 
the free-living form. The protozoan association with other organ- 
isms was begun when various protozoans which lived attached to, 
or by crawling on, submerged objects happened to transfer them- 
selves to various invertebrates which occur in the same water. 
These Protozoa benefit by change in location as the host animal 
moves about, and thus enlarging the opportunity to obtain a con- 
tinued supply of food material. Such ectocommensals are found 
abundantly; for example, the peritrichous ciliates attached to the 
body and appendages of various aquatic animals such as larval in- 
sects and microcrustaceans. Ectocommensalism may next lead to 
ectoparasitism as in the case of Costia or Hydramoeba, and then 
again instead of confining themselves to the body surface, the Pro- 
tozoa may bore into the body wall from outside and actually acquire 
the habit of feeding on tissue cells of the attached animals as in the 
case of Ichthyophthirius. 

The next step in the evolution of parasitism must have been 
reached when Protozoa, accidentally or passively, were taken into 
the digestive system of the Metazoa. Such a sudden change in 
habitat appears to be fatal to most protozoans. But certain others 


possess extraordinary capacity to adapt themselves to an entirely 
different environment. For example, Dobell (1918) observed in the 
tadpole gut, a typical free-living limax amoeba, with characteristic 
nucleus, contractile vacuoles, etc., which was found in numbers in 
the water containing the faecal matter of the tadpole. Glaucoma 
(Tetrahymena) pyriformis, a free-living ciliate, was found to occur 
in the body cavity of the larvae of Theobaldia annulata (after 
MacArthur) and in the larvae of Chironomus plumosus (after Treil- 
lard and Lwoff). Lwoff successfully inoculated this ciliate into the 
larvae of Galleria mellonella which died later from the infection. 
Janda and Jirovec (1937) injected bacteria-free culture of this 
ciliate into annelids, molluscs, crustaceans, insects, fishes, and 
amphibians, and found that only insects — all of 14 species (both 
larvae and adults) — became infected by this ciliate. In a few days 
after injection the haemocoele became filled with the ciliates. Of 
various organs, the ciliates were most abundantly found in the 
adipose tissue. The organisms were much larger than those present 
in the original culture. The insects, into which the ciliates were in- 
jected, died from the infection in a few days. The course of develop- 
ment of the ciliate within an experimental insect depended not only 
on the amount of the culture injected, but also on the temperature. 
At 1-4°C. the development was much slower than at 26°C; but if 
an infected insect was kept at 32-36°C. for 0.5-3 hours, the ciliates 
were apparently killed and the insect continued to live. When 
Glaucoma taken from Dixippus morosus were placed in ordinary 
water, they continued to live and underwent multiplication. The 
ciliate showed a remarkable power of withstanding the artificial 
digestion; namely, at 18°C. they lived 4 days in artificial gastric 
juice with pH 4.2; 2-3 days in a juice with pH 3.6; and a few hours 
in a juice with pH 1.0. Cleveland (1928) observed Tritrichomonas 
fecalis in faeces of a single human subject for three years which grew 
well in faeces diluted with tap water, in hay infusions with or with- 
out free-living protozoans or in tap water with tissues at —3° to 
37°C, and which, when fed per os, was able to live indefinitely in 
the gut of frogs and tadpoles. Reynolds (1936) found that Colpoda 
steini, a free-living ciliate of fresh water, occurs naturally in the 
intestine and other viscera of the land slug, Agriolimax agrestis, the 
slug forms being much larger than the free-living individuals. 

It may be further speculated that Vahlkampfia, Hydramoeba, 
Schizamoeba, and Endamoeba, are the different stages of the course 
the intestinal amoebae might have taken during their evolution. 
Obviously endocommensalism in the alimentary canal was the 
initial phase of endoparasitjsm. When these endocommensals began 


to consume an excessive amount of food or to feed on the tissue cells 
of the host gut, they became the true endoparasites. Destroying or 
penetrating through the intestinal wall, they became first established 
in the body or organ cavities and then invaded tissues, cells or even 
nuclei, thus developing into pathogenic Protozoa. The endoparasites 
developing in invertebrates which feed upon the blood of vertebrates 
as source of food supply, will have opportunities to establish them- 
selves in the higher animals. 

Hyperparasitism. Certain parasitic Protozoa have been found to 
parasitize other protozoan or metazoan parasites. This association is 
named hyperparasitism. The microsporidian Nosema notabilis (p. 
672) is an exclusive parasite of the myxosporidian Sphaerospora 
polymorpha, which is a very common inhabitant of the urinary blad- 
der of the toad fish along the Atlantic and Gulf coasts. A heavy in- 
fection of the microsporidian results in the degeneration and death 
of the host myxosporidian trophozoite (Kudo, 1944). Thus Nosema 
notabilis is a hyperparasite. Organisms living on and in Protozoa 
(Duboscq and Grasse, 1927, 1929; Georgevitch, 1936; Grasse, 1936; 
Kirby, 1932, 1938, 1941, 1941a, 1942, 1942a, 1942b, 1944, 1946) 


Bland, P. B., Goldstein, L., Wenrich, D. H. and Weiner, Elea- 
nor: (1932) Studies on the biology of Trichomonas vaginalis. 
Am. J. Hyg., 56:492. 

Chalkley, H. W. : (1930) Resistance of Paramecium to heat as af- 
fected by changes in hydrogen-ion concentration and in inor- 
ganic salt balance in surrounding medium. U. S. Pub. Health, 
Rep., 45:481. 

Chambers, R. and Hale, H. P.: (1932) The formation of ice in pro- 
toplasm. Proc. Roy. Soc. London, Ser. B, 110:336. 

Cleveland, L. R. : (1924) The physiological and symbiotic relation- 
ships between the intestinal protozoa of termites and their host, 
with special reference to Reticulitermes flavipes Kollar. Biol. 
Bull., 46:177. 
(1925) The effects of oxygenation and starvation on the sym- 
biosis between the termite, Termopsis, and its intestinal flagel- 
lates. Ibid., 48:309. 

— (1926) Symbiosis among animals with special reference to 
termites and their intestinal flagellates. Gen. Rev. Biol., 1:51. 

— (1928) Tritrichomonas fecalis nov. sp. of man, etc. Amer. J. 
Hyg., 8:232. 

(1949) Hormone-induced sexual cycles of flagellates. I. Jour. 

Morph., 85:197. 

- (1950) II. Ibid., 86:185. 

- (1950a) III. Ibid., 86:215. 

- (1950b) IV. Ibid, 87:317. 
— (1950c) V. Ibid, 87:349. 


Coggeshall, L. T. : (1939) Preservation of viable malaria parasites 

in the frozen state. Proc. Soc. Exp. Biol., 42:499. 
Oulbertson, J. T. : (1951) Immunological mechanisms in parasitic. 

infections. In: Most's Parasitic infections in man. New York. 
Dallinger, W. H.: (1887) The president's address. J. Roy. Micro. 

Soc, London, 7:185. 
Darby, H. H.: (1929) The effect of the hydrogen-ion concentration 

on the sequence of protozoan forms. Arch. Protist., 65:1. 
Dennis, E. W. : (1932) The life-cycle of Babesia bigemina, etc., Univ. 

Cal. Publ. Zoology, 36:263. 
Deschiens, R. : (1934) Influence du froid sur les formes vegetatives 

de ramibe dysenterique. C. R. Soc. Biol., 115:793. 
Dobell, C. : (1918) Are Entamoeba histolytica and E. ranarum the 

same species? Parasit., 10:294. 
Doudoroff, M.: (1936) Studies in thermal death in Paramecium. J. 

Exper. Zool., 72:369. 
Drew, G. H.: (1911) Experimental metaphasia. I. J. Exper. Zool., 

Duboscq, O. and Grasse, P.: (1927) Flagelles et Schizophytes de 

Calotermes (Glyptotermes) iridipennis. Arch. zool. exp. gen., 66: 


— (1929) Sur quelques protistes d'un Calotermes, etc. 
Ibid., 68:8. 

Efimoff, W. W. : (1924) Ueber Ausfrieren und Ueberkaeltung der 

Protozoen. Arch. Protist., 49: 431. 
Fatjre-Fremiet, E.: (1950) Ecology of ciliate infusoria. Endeavour 

9, 3 pp. 
(1951) The marine sand-dwelling ciliates of Cape Cod. Biol. 

Bull., 100:59. 

(1951a) Ecologie des Protistes littoraux. Ann. Biol., 27:205. 

Finley, H. E. : (1930) Toleration of freshwater Protozoa to increased 

salinity. Ecology, 11:337. 
Frisch, J. A.: (1939) The experimental adaptation of Paramecium 

to sea water. Arch. Protist., 93:38. 
Gaylord, H. R.: (1908) The resistance of embryonic epithelium, 

etc. J. Infect. Dis., 5:443. 
Georgevitch, J.: (1936) Ein neuer Hyperparasit, Leishmania esocis 

n. sp. Arch. Protist., 88:90. 
Glaser, R. W. and Coria, N. A.: (1933) The culture of Paramecium 

caudatum free from living microorganisms. Jour. Parasit., 20: 


— (1935) The culture and reactions of purified Protozoa. 
Am. J. Hyg, 21:111. 

Grasse, P. P.: (1938) La veture schizophytique des flagelles ter- 
miticoles, etc. Bull. Soc. zool. France, 63:110. 

Greeley, A. W. : (1902) On the analogy between the effects of loss 
of water and lowering of temperature. Amer. Jour. Physiol., 6: 

Hardin, G. : (1944) Symbiosis of Paramecium and Oikomonas. Ecol- 
ogy, 25:304. 


Hassanein, M. H. : (1951) Studies on the effect of infection with 
Nosema apis on the physiology of the queen honey-bee. Quart. 
J. Micr. Sc, 92:225. 

Howland, Ruth: (1930) Micrurgical studies on the contractile vac- 
uole. III. J. Exper. Zool., 55:53. 

Jahn, T. L. : (1933) Studies on the physiology of the euglenoid flag- 
ellates. IV. Arch. Protist., 79:249. 

Janda, V. and Jirovec, O. : (1937) Ueber kiinstlich hervorgerufenen 
Parasitismus eines freilebenden Ciliaten Glaucoma piriformis, 
etc. Mem. Soc. Zool. Tehee. Prague, 5:34. 

Kidder, G. W.: (1941) Growth studies on ciliates. VII. Biol. Bull, 

Kirby, H. Jr.: (1932) Flagellates of the genus Trichonympha in 
termites. Univ. Cal. Publ. Zool., 37:349. 

— (1938) The devescovinid flagellates, etc. Ibid., 43:1. 

— (1941) Devescovinid flagellates of termites. I. Ibid., 45:1. 

— (1941a) Organisms living on and in Protozoa. Calkins and 
Summers' Protozoa in biological research. 

— (1942) Devescovinid flagellates of termites. II. Uni. Cal. 
Publ. Zool., 45:93. 

— (1942a) III. Ibid., 45:167. 

— (1942b) A parasite of the macronucleus of Vorticella. Jour. 
Parasit., 28:311. 

(1944) The structural characteristics and nuclear parasites 

of some species of Trichonympha in termites. Uni. Cal. Publ. 
Zool., 49:185. 

(1946) Gigayitomonas herculea, etc. Ibid., 53:163. 

Klebs, G.: (1893) Flagellatenstudien. Zeitschr. wiss. Zool, 55: 

Kolkwitz, R. and Marsson, M.: (1909) Oekologie der tierischen 

Sabrobien. Intern. Rev. Ges. Hydrobiol. u. Hydrogr., 2:126. 
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sporidia. Illinois Biol. Monogr., 9: nos. 3 and 4. 
(1929) Histozoic Myxosporidia found in freshwater fishes of 

Illinois, U. S. A. Arch. Protist., 65:364. 
— (1944) Morphology and development of Nosema notabilis 

Kudo, parasitic in Sphaerospora polymorpha Davis, a parasite 

of Opsanus tau and 0. beta. Illinois Biol. Monogr., 20:1. 
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(1938) Effect of hydrogen-ion concentration on the growth 

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Uyemura, M.: (1936) Biological studies of thermal waters in Japan. 
IV. Ecolog. St., 2:171. 

— (1937) V. Rep. Japan. Sc. A., 12:264. 

Vevers, H. G.: (1951) The biology of Asterias rubens. II. J. Mar. 

Biol. A. Un. Kingd. 29:619. 
Wichterman, R. : (1948) The hydrogen-ion concentration in the 

cultivation and growth of 8 species of Paramecium. Biol. Bull., 

Wolfson, C. : (1935) Observations on Paramecium during exposure 

to sub-zero temperatures. Ecology, 16:630. 
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of certain freshwater ciliates to sea water. Biol. Bull, 67:273. 

Chapter 3 

PROTOZOA range in size from submicroscopic to macroscopic, 
though they are on the whole minute microscopic animals. The 
parasitic forms, especially cytozoic parasites, are often extremely 
small, while free-living protozoans are usually of much larger dimen- 
sions. Noctiluca, Foraminifera, Radiolaria, many ciliates such as 
Stentor, Bursaria, etc., represent larger forms. Colonial proto- 
zoans such as Carchesium, Zoothamnium, Ophrj^dium, etc., are even 
greater than the solitary forms. On the other hand, Plasmodium, 
Leishmania, and microsporidian spores may be mentioned as exam- 
ples of the smallest forms. The unit of measurement employed in 
protozoology is, as in general microscopy, 1 micron (n) which is 
equal to 0.001 mm. 

The body form of Protozoa is even more varied, and because of 
its extreme plasticity it frequently does not remain constant. Fur- 
thermore the form and size of a given species may vary according to 
the kind and amount of food as is discussed elsewhere (p. 109). From 
a small simple spheroidal mass up to large highly complex forms, all 
possible body forms occur. Although the great majority are without 
symmetry, there are some which possess a definite symmetry. Thus 
bilateral symmetry is noted in all members of Diplomonadina (p. 
392); radial symmetry in Gonium, Cyclonexis, etc.; and universal 
symmetry, in certain Heliozoa, Vol vox, etc. 

The fundamental component of the protozoan body is the pro- 
toplasm which is without exception differentiated into the nucleus 
and the cytoplasm. Haeckel's (1868, 1870) monera are now considered 
as nonexistent, since improved microscopic technique has failed in re- 
cent years to reveal any anucleated protozoans. The nucleus and the 
cytoplasm are inseparably important to the well-being of a proto- 
zoan, as has been shown by numerous investigators since Verworn's 
pioneer work. In all cases, successful regeneration of the body is ac- 
complished only by the nucleus-bearing portions and enucleate parts 
degenerate sooner or later. On the other hand, when the nucleus is 
taken out of a protozoan, both the nucleus and cytoplasm degener- 
ate, which indicates their intimate association in carrying on the 
activities of the body. It appears certain that the nucleus controls 
the assimilative phase of metabolism which takes place in the cyto- 
plasm in normal animals, while the cytoplasm is capable of carrying 
on the catabolic phase of the metabolism. Aside from the importance 



as the controlling center of metabolism, evidences point to the con- 
clusion that the nucleus contains the genes or hereditary factors 
which characterize each species of Protozoa from generation to gen- 
eration, as in the cells of multicellular animals and plants. 

The nucleus 

Because of a great variety of the body form and organization, the 
protozoan nuclei are of various forms, sizes and structures. At one 
extreme there is a small nucleus and, at the other, a large voluminous 
one and, between these extremes, is found almost every conceivable 
variety of form and structure. The majority of Protozoa contain a 
single nucleus, though many may possess two or more throughout 
the greater part of their life-cycle. In several species, each individual 
possesses two similar nuclei, as in Diplomonadina, Protoopalina 
and Zelleriella. In Euciliata and Suctoria, two dissimilar nuclei, a 
macronucleus and a micronucleus, are typically present. The macro- 
nucleus is always larger than the micronucleus, and controls the 
trophic activities of the organism, while the micronucleus is con- 
cerned with the reproductive activity. Certain Protozoa possess 
numerous nuclei of similar structure, as for example, in Pelomyxa, 
Mycetozoa, Actinosphaerium, Opalina, Cepedea, Myxosporidia, 
Microsporidia, etc. 

The essential morphological components of the protozoan nucleus 
are the nuclear membrane, chromatin, plastin and nucleoplasm or 
nuclear sap. Their interrelationship varies sometimes from one de- 
velopmental stage to another, and vastly among different species. 
Structurally, they fall in general into one of the two types: vesicular 
and compact. 

The vesicular nucleus (Fig. 2, a, c, e) consists of a nuclear mem- 
brane which is sometimes very delicate but distinct, nucleoplasm, 
achromatin and chromatin. Besides there is an intranuclear body 
which is, as a rule, more or less spherical and which appears to be of 
different make-ups as judged by its staining reactions among differ- 
ent nuclei. It may be composed of chromatin, of plastin, or of a 
mixture of both. The first type is sometimes called karyosome and 
the second, nucleolus or plasmosome. Absolute distinction between 
these two terms cannot be made as they are based solely upon the 
difference in affinity to nuclear stains which cannot be standardized 
and hence do not give uniformly the same result. Following Minchin 
(1912), the term endosome is advocated here to designate one or 
more conspicuous bodies other than the chromatin granules, present 
within the nuclear membrane (Fig, 2, b, d). 

Fig. 2. a-f, vesicular nuclei; g-j, compact nuclei, X980. a, b, nuclei of 
Entamoeba invadens (a, in life; b, in stained organism); c, d, nuclei of 
Amoeba spumosa (c, in life, showing a large endosome; d, stained); e, f, 
nuclei of A. proteus (e, in life; f, a nucleus subjected to Feulgen's nucleal 
reaction) ; g, h, nuclei of Paramecium aurelia (g, in life under phase micro- 
scope, snowing two vesicular micronuclei and compact macronucleus; h, 
Feulgen-stained nuclei); i, j, nuclei of Frontonia leucas, showing a micro- 
nucleus and macronucleus, both of which are compact ($ in life, showing 
many endosomes imbedded among the granules; j, nuclei stained with 
acidified methyl green), 


When viewed in life, the nucleoplasm is ordinarily homogeneous 
and structureless. But, upon fixation, there appear invariably achro- 
matic strands or networks which seem to connect the endosome and 
the nuclear membrane (Fig. 2, b, d). Some investigators hold that 
these strands or networks exist naturally in life, but due to the simi- 
larity of refractive indices of the strands and of the nucleoplasm, 
they are not visible and that, when fixed, they become readily recog- 
nizable because of a change in these indices. In some nuclei, however, 
certain strands have been observed in life, as for example in the 
nucleus of the species of Barbulanympha (Fig. 174, c), according to 
Cleveland and his associates (1934). Others maintain that the achro- 
matic structures prominent in fixed vesicular nuclei are mere arti- 
facts brought about by fixation and do not exist in life and that the 
nucleoplasm is a homogeneous liquid matrix of the nucleus in which 
the chromatin is usually distributed as small granules. Frequently 
larger granules of various sizes and forms may occur along the inner 
surface of the nuclear membrane. These so-called peripheral granules 
that occur in Amoeba, Entamoeba, Pelomyxa, etc., are apparently 
not chromatinic (Fig. 2, a, e). The vesicular nucleus is most com- 
monly present in various orders of Sarcodina and Mastigophora. 

The compact nucleus (Fig. 2, g-j), on the other hand, contains a 
large amount of chromatin substance and a comparatively small 
amount of nucleoplasm, and is thus massive. The macronucleus of 
the Ciliophora is almost always of this kind. The variety of forms 
of the compact nuclei is indeed remarkable. It may be spherical, 
ovate, cylindrical, club-shaped, band-form, moniliform, horseshoe- 
form, filamentous, or dendritic. The nuclear membrane is always 
distinct, and the chromatin substance is usually of spheroidal form, 
varying in size among different species and often even in the same 
species. In the majority of species, the chromatin granules are small 
and compact (Fig. 2, h, i), though in some forms, such as Nyctotheru-s 
ovalis (Fig. 3), they may reach 20/x or more in diameter in some indi- 
viduals and while the smaller chromatin granules seem to be homo- 
geneous, larger forms contain alveoli of different sizes in which 
smaller chromatin granules are suspended (Kudo, 1936). 

Precise knowledge of chromatin (thymo- or desoxyribose-nucleic 
acid) is still lacking. At present the determination of the chromatin 
depends upon the following tests: (1) artificial digestion which does 
not destroy this substance, while non-chromatinic parts of the nu- 
cleus are completely dissolved; (2) acidified methyl green which 
stains the chromatin bright green; (3) 10 per cent sodium chloride 
solution which dissolves, or causes swelling of, chromatin granules, 



while nuclear membrane and achromatic substances remain unat- 
tacked; and (4) in the fixed condition Feulgen's nucleal reaction 
(p. 897). Action of methyl green (Pollister and Leuchtenberger, 

There is no sharp demarcation between the vesicular and compact 
nuclei, since there are numerous nuclei the structures of which are 

Fig. 3. Parts of 

nacronuclei of Nyctotherus ovalis, showing chromatin 
spherules of different sizes, X650 (Kudo). 

intermediate between the two. Moreover what appears to be a 
vesicular nucleus in life, may approach a compact nucleus when 
fixed and stained as in the case of Euglenoidina. Several experimental 
observations show that the number, size, and structure of the endo- 
some in the vesicular nucleus, and the amount and arrangement of 
the chromatin in the compact nucleus, vary according to the physio- 
logical state of the whole organism. The macronucleus may be 


divided into two or more parts with or without connections among 
them and in Dileptus anser into more than 200 small nuclei, each of 
which is "composed of a plastin core and a chromatin cortex" (Cal- 
kins; Hayes). 

In a compact nucleus, the chromatin granules or spherules fill, as 
a rule, the intranuclear space compactly, in which one or more endo- 
somes (Fig. 2, i) may occur. In many nuclei these chromatin granules 
appear to be suspended freely, while in others a reticulum appears to 
make the background. The chromatin of compact nuclei gives a 
strong positive Feulgen's nucleal reaction. The macronuclear and 
micronuclear chromatin substances respond differently to Feulgen's 
nucleal reaction or to the so-called nuclear stains, as judged by the 
difference in the intensity or tone of color. In Paramecium caudatum., 
P. aurelia, Chilodonella, Nyctotherus ovalis, etc., the macronuclear 
chromatin is colored more deeply than the micronuclear chromatin, 
while in Colpoda, Urostyla, Euplotes, Stylonychia, and others, the 
reverse seems to be the case, which may support the validity of the 
assumption by Heidenhain that the two types of the nuclei of 
Euciliata and Suctoria are made up of different chromatin sub- 
stances — idiochromatin in the micronucleus and trophochromatin 
in the macronucleus — and in other classes of Protozoa, the two kinds 
of chromatin are present together in a single nucleus. The macro- 
nucleus and the micronucleus of vegetative Paramecium caudatum 
were found by Moses (1950) to possess a similar nucleic acid-protein 
composition; namely, similar concentrations of total protein, non- 
histone protein, desoxyribose nucleic acid and ribose nucleic acid. 
Of the two latter nucleic acids, ribose nucleic acid is said to be pres- 
ent in a larger amount than desoxyribose nucleic acid in both nuclei. 
It may be considered that the two nucleic acids occur in different 
proportions in the two nuclei. 

Chromidia. Since the detection of chromatin had solely depended 
on its affinity to certain nuclear stains, several investigators found 
extranuclear chromatin granules in many protozoans. Finding such 
granules in the cytoplasm of Actinosphaerium eichhorni, Arcella vul- 
garis, and others, Hertwig (1902) called them chromidia, and main- 
tained that under certain circumstances, such as lack of food ma- 
terial, the nuclei disappear and the chromatin granules become scat- 
tered throughout the cytoplasm. In the case of Arcella vulgaris, the 
two nuclei break down completely to produce a chromidial-net 
which later reforms into smaller secondary nuclei. It has, however, 
been found by Belaf that the lack of food caused the encystment 
rather than chromidia-formation in Actinosphaerium and, according 


to Reichenow, Jollos observed that in Arcella the nuclei persisted, 
but were thickly covered by chromidial-net which could be cleared 
away by artificial digestion to reveal the two nuclei. In Diffiugia, the 
chromidial-net is vacuolated or alveolated in the fall and in each 
alveolus appear glycogen granules which seem to serve as reserve 
food material for the reproduction that takes place during that 
season (Zuelzer), and the chromidia occurring in Actinosphaerium 
appear to be of a combination of a carbohydrate and a protein 
(Rumjantzew and Wermel, 1925). Apparently the widely distributed 
volutin (p. 114), and many inclusions or cytozoic parasites, such as 
Sphaerita (p. 893), which occur occasionally in different Sarcodina, 
have in some cases been called chromidia. By using Feulgen's nucleal 
reaction, Reichenow (1928) obtained a diffused violet-stained zone 
in Chlamydomonas and held them to be dissolved volutin. Calkins 
(1933) found the chromidia of Arcella vulgaris negative to the nucleal 
reaction, but by omitting acid-hydrolysis and treating with fuchsin- 
sulphurous acid for 8-14 hours, the chromidia and the secondary 
nuclei were found to show a typical positive reaction and believed 
that the chromidia were chromatin. Thus at present the real nature 
of chromidia is still not clearly known, although many protozoolo- 
gists are inclined to think that the substance is not chromatinic, but, 
in some way, is connected with the metabolism of the protozoan. 

The cytoplasm 

The extranuclear part of the protozoan body is the cytoplasm. It 
is composed of a colloidal system, which may be homogeneous, granu- 
lated, vacuolated, reticulated, or fibrillar in optical texture, and is 
almost always colorless. The chromatophore-bearing Protozoa are 
variously colored, and those with symbiotic algae or cryptomonads 
are also greenish or brownish in color. Furthermore, pigment or 
crystals which are produced in the body may give protozoans vari- 
ous colorations. In several forms pigments are diffused throughout 
the cytoplasm. For example, many dinoflagellates are beautifully 
colored, which, according to Kofoid and Swezy, is due to a thorough 
diffusion of pigment in the cytoplasm. 

Stentor coeruleus is beautifully blue-colored. This coloration is due 
to the presence of pigment stentorin (Lankester, 1873) which occurs 
as granules in the ectoplasm (Fig. 14). The pigment is highly re- 
sistant to various solvents such as acids and alkalis, and the sun- 
light does not affect its nature. It is destroyed by bleaching with 
chlorine gas or with potassium permanganate, followed by immer- 
sion in 5 per cent oxalic acid (Weisz, 1948). Several species of Blepha- 


risma are rose- or purple-colored. The color is due to the presence of 
zoopurpurin (Arcichovskij, 1905) which is lodged in numerous gran- 
ules present in the ectoplasm. This pigment is soluble in alcohol, 
ether or acetone, and is destroyed by strong light (Giese, 1938). 
Weisz (1950) maintains that both pigment granules are chondrio- 
somes, and in Stentor, cytochrome oxidase appears to be localized in 
the pigment granules. 

The extent and nature of the cytoplasmic differentiation differ 
greatly among various groups. In the majority of Protozoa, the 
cytoplasm is differentiated into the ectoplasm and the endoplasm. 
The ectoplasm is the cortical zone which is hyaline and homogeneous 
in Sarcodina and Sporozoa. In the Ciliophora it is a permanent and 
distinct part of the body and contains several organelles. The endo- 
plasm is more voluminous and fluid. It is granulated or alveolated 
and contains various organellae. While the alveolated cytoplasm is 
normal in forms such as the members of Heliozoa and Radiolaria, in 
other cases the alveolation of normally granulated or vacuolated 
cytoplasm indicates invariably the beginning of degeneration of the 
protozoan body. In Amoeba and other Sarcodina, the "hyaline cap" 
and "layer" (Mast) make up the ectoplasm, and the "plasmasol" 
and "plamagel" (Mast) compose the endoplasm (Fig. 46). 

In numerous Sarcodina and certain Mastigophora, the body 
surface is naked and not protected by any form-giving organella. 
However, the surface layer is not only elastic, but solid, and there- 
fore the name plasma-membrane may be applied to it. Such forms 
are capable of undergoing amoeboid movement by formation of 
pseudopodia and by continuous change of form due to the movement 
of the cytoplasm which is more fluid. However, the majority of 
Protozoa possess a characteristic and constant body form due to the 
development of a special envelope, the pellicle. In Amoeba striata, 
A. verrucosa (Howland, 1924), Pelomyxa carolinensis, P. illinoisensis 
(Kudo, 1946, 1951), etc., there is a distinct pellicle. The same is true 
with some flagellates, such as certain species of Euglena, Peranema, 
and Astasia, in which it is elastic and expansible so that the organ- 
isms show a great deal of plasticity. 

The pellicle of a ciliate is much thicker and more definite, and 
often variously ridged or sculptured. In many, linear furrows and 
ridges run longitudinally, obliquely, or spirally; and, in others, the 
ridges are combined with hexagonal or rectangular depressed areas. 
Still in others, such as Coleps, elevated platelets are arranged paral- 
lel to the longitudinal axis of the body. In certain peritrichous 
ciliates, such as Vorticella monilata, Carchesium granulatum, etc., 


the pellicle may possess nodular thickenings arranged in more or less 
parallel rows at right angles to the body axis. 

While the pellicle always covers the protozoan body closely, 
there are other kinds of protective envelopes produced by Protozoa 
which may cover the body rather loosely. These are the shell, test, 
lorica or envelope. The shell of various Phytomastigina is usually 
made up of cellulose, a carbohydrate, which is widely distributed 
in the plant kingdom. It may be composed of a single or several 
layers, and may possess ridges or markings of various patterns on it. 
In addition to the shell, gelatinous substance may in many forms be 
produced to surround the shelled body or in the members of Volvo- 
cidae to form the matrix of the entire colony in which the individuals 
are embedded. In the dinoflagellates, the shell is highly developed 
and often composed of numerous plates which are variously sculp- 

In other Protozoa, the shell is made up of chitin or pseudo-chitin 
(tectin). Common examples are found in the testaceans; for example, 
in Arcella and allied forms, the shell is made up of chitinous material 
constructed in particular ways which characterize the different gen- 
era. Newly formed shell is colorless, but older ones become brownish, 
because of the presence of iron oxide. Difflugia and related genera 
form shells by gluing together small sand-grains, diatom-shells, 
debris, etc., with chitinous or pseudochitinous substances which 
they secrete. Many foraminiferans seem to possess a remarkable 
selective power in the use of foreign materials, for the construction of 
their shells. According to Cushman (1933) Psammosphaera fusca 
uses sand-grains of uniform color but of different sizes, while P. parva 
uses grains of more or less uniform size but adds, as a rule, a single 
large acerose sponge spicule which is built into the test and which 
extends out both ways considerably. Cushman thinks that this is not 
accidental, since the specimens without the spicules are few and those 
with a short or broken spicules are not found. P. bowmanni, on the 
other hand, uses only mica flakes which are found in a comparatively 
small amount, and P. rustica uses acerose sponge spicules for the 
framework of the shell, skilfully fitting smaller broken pieces into 
polygonal areas. Other foraminiferans combine chitinous secretion 
with calcium carbonate and produce beautifully constructed shells 
(Fig. 4) with one or numerous pores. In the Coccolithidae, variously 
shaped platelets of calcium carbonate ornament the shell. 

The silica is present in the shells of various Protozoa. In Euglypha 
and related testaceans, siliceous scales or platelets are produced in 
the endoplasm and compose a new shell at the time of fission or of 


encystment together with the chitinous secretion. In many helio- 
zoans, siliceous substance forms spicules, platelets, or combination 
of both which are embedded in the mucilaginous envelope that 
surrounds the body and, in some cases, a special clathrate shell com- 
posed of silica, is to be found. In some Radiolaria, isolated siliceous 
spicules occur as in Heliozoa, while in others the lateral development 

Fig. 4. Diagram of the shell of Peneroplis pertusus, X about 35 
(Carpenter), ep, external pore; s, septum; sc, stolon canal. 

of the spines results in production of highly complex and the most 
beautiful shells with various ornamentations or incorporation of 
foreign materials. Many pelagic radiolarians possess numerous con- 
spicuous radiating spines in connection with the skeleton, which ap- 
parently aid the organisms in maintaining their existence in the open 

Certain Protomonadina possess a funnel-like collar in the flagel- 
lated end and in some in addition a chitinous lorica surrounds the 
body. The lorica found in the Ciliophora is mostly composed of 
chitinous substance alone, especially in Peritricha, although others 
produce a house made up of gelatinous secretion containing foreign 
materials as in Stentor (p. 806). In the Tintinnidae, the loricae 
are either solely chitinous in numerous marine forms not mentioned 
in the present work or composed of sand-grains or coccoliths ce- 
mented together by chitinous secretion, which are found in fresh- 
water forms. 


Locomotor organellae 

Closely associated with the body surface are the organellae of 
locomotion: pseudopodia, flagella, and cilia. These organellae are not 
confined to Protozoa alone and occur in various cells of Metazoa. 
All protoplasmic masses are capable of movement which may result 
in change of their forms. 

Pseudopodia. A pseudopodium is a temporary projection of part 
of the cytoplasm of those protozoans which do not possess a definite 
pellicle. Pseudopodia are therefore a characteristic organella of 
Sarcodina, though many Mastigophora and certain Sporozoa, which 
lack a pellicle, are also able to produce them. According to their 
form and structure, four kinds of pseudopodia are distinguished. 

1). Lobopodium is formed by an extension of the ectoplasm, 
accompanied by a flow of endoplasm as is commonly found in 
Amoeba proteus (Figs. 46; 184). It is finger- or tongue-like, sometimes 
branched, and its distal end is typically rounded. It is quickly 
formed and equally quickly retracted. In many cases, there are 
many pseudopodia formed from the entire body surface, in which 
the largest one will counteract the smaller ones and the organism 
will move in one direction; while in others, there may be a single 
pseudopodium formed, as in Amoeba striata, A. guttula, Pelomyxa 
carolinensis (Fig. 186, b), etc., in which case it is a broadly tongue- 
like extension of the body in one direction and the progressive move- 
ment of the organisms is comparatively rapid. The lobopodia may 
occasionally be conical in general shape, as in Amoeba spumosa (Fig. 
185, a). Although ordinarily the formation of lobopodia is by a gen- 
eral flow of the cytoplasm, in some it is sudden and "eruptive," as in 
Entamoeba blattae or Entamoeba histolytica in which the flow of the 
endoplasm presses against the inner zone of the ectoplasm and the 
accumulated pressure finally causes a break through the zone, result- 
ing in a sudden extension of the endoplasmic flow at that point. 

2). Filopodium is a more or less filamentous projection com- 
posed almost exclusively of the ectoplasm. It may sometimes be 
branched, but the branches do not anastomose. Many testaceans, 
such as Lecythium, Boderia, Plagiophrys, Pamphagus, Euglypha, 
etc., form this type of pseudopodia. The pseudopodia of Amoeba 
radiosa may be considered as approaching this type rather than the 

3). Rhizopodium is also filamentous, but branching and 
anastomosing. It is found in numerous Foraminifera, such as 
Elphidium (Fig. 5), Peneroplis, etc., and in certain testaceans, such 



as Lieberkuhnia, Myxotheca, etc. The abundantly branching and 
anastomosing rhizopodia often produce a large network which serves 
almost exclusively for capturing prey. 

lift, \^i ;;:;;: ;l ; 



Fig. 5. Pseudopodia of Elphidium strigilata, X about 50 
(Schulze from Kiihn). 

4). Axopodium is, unlike the other three types, a more or less 
semi-permanent structure and composed of axial rod and cytoplas- 
mic envelope. Axopodia are found in many Heliozoa, such as Actino- 
phrys, Actinosphaerium, Camptonema, Sphaerastrum, and Acan- 



thocystis. The axial rod, which is composed of a number of fibrils 
(Doeflein; Roskin, 1925; Rumjantzew and Wermel, 1925), arises 
from the central body or the nucleus located in the approximate 
center of the body, from each of the nuclei in multinucleate forms, 
or from the zone between the ectoplasm and endoplasm (Fig. 6). 
Although semipermanent in structure, the axial rod is easily ab- 
sorbed and reformed. In the genera of Heliozoa not mentioned 
above and in numerous radiolarians, the radiating filamentous 
pseudopodia are so extremely delicate that it is difficult to determine 



c v 



7\A\. -| '"•-/ 


Fig. 6. Portion of Actinosphaerium eichhorni, X800 (Kiihn). ar, axial rod; 
cv, contractile vacuole; ec, ectoplasm; en, endoplasm; n, nucleus. 

whether an axial rod exists in each or not, although they resemble 
axopodia in general appearance. 

There is no sharp demarcation between the four types of pseudo- 
podia, as there are transitional pseudopodia between any two of 
them. For example, the pseudopodia formed by Arcella, Lesquer- 
eusia, Hyalosphaenia, etc., resemble more lobopodia than filopodia, 
though composed of the ectoplasm only. The pseudopodia of Actino- 
monas, Elaeorhanis, Clathrulina, etc., may be looked upon as 
transitional between rhizopodia and axopodia. 

While the pseudopodia formed by an individual are usually of 
characteristic form and appearance, they may show an entirely 
different appearance under different circumstances. According to 



the often-quoted experiment of Verworn, a Umax amoeba changed 
into a radiosa amoeba upon addition of potassium hydroxide to the 
water (Fig. 7). Mast has recently shown that when Amoeba proteus 
or A . dubia was transferred from a salt medium into pure water, the 
amoeba produced radiating pseudopodia, and when transferred 
back to a salt medium, it changed into monopodal form, which 
change he was inclined to attribute to the difference in the water 
contents of the amoeba. In some cases during and after certain in- 
ternal changes, an amoeba may show conspicuous differences in 

Fig. 7. Form-change in a limax-amoeba (Verworn). a, b, contracted 
forms; c, individual showing typical form; d-f, radiosa-forms, after ad- 
dition of KOH solution to the water. 

pseudopodia (Neresheimer). As was stated before, pseudopodia occur 
widely in forms which are placed under classes other than Sarcodina 
during a part of their life-cycle. Care, therefore, should be exer- 
cised in using them for taxonomic consideration of the Protozoa. 
Flagella. The flagellum is a filamentous extension of the cytoplasm 
and is ordinarily extremely hue and highly vibratile, so that it is 
difficult to recognize it distinctly in life under the microscope. It is 
most clearly observed under a darkfield or phase microscope. Lugol's 
solution usually makes it more easily visible, though the organism is 
killed. In a small number of species, the flagellum can be seen in life 
under an ordinary microscope as a long filament, as for example in 



Peranema. As a rule, the number of flagella present in an individual 
is small, varying from one to eight and most commonly one or two; 
but in Hypermastigina there occur numerous flagella. 

A flagellum appears to be composed of two parts: an elastic axial 
filament or axoneme, made up of one to several fibrils and the con- 
tractile cytoplasmic sheath surrounding the axoneme (Fig. 8, a, b). 
In some flagella, both components extend the entire length and 
terminate in a bluntly rounded point, while in others the distal por- 
tion of the axoneme is apparently very thinly sheathed (Fig. 8, c). 

Fig. 8. Diagrams of flagella. a, flagellum of Euglena (Butschli); b, 
flagellum of Trachelomonas (Plenge); c, flagella of Polytoma uvella; d, 
flagella of Monas socialis (Vlk). 

In some flagellates, stained flagella show numerous lateral fibrils 
(Fig. 8, d) (Fischer, 1894; Dellinger, 1909; Mainx, 1929; Petersen, 
1929; etc.). These flagella or ciliary flagella have also been noticed 
by several observers in unstained organisms under darkfield micro- 
scope (Vlk, 1938; Pitelka, 1949). In recent years, the electron micro- 
scope has been used by some to observe the flagellar structure 
(Schmitt, Hall and Jakus, 1943; Brown, 1945; Pitelka, 1949; Chen, 
1950), but in all cases, the organisms were air-dried on collodion 
films for examination so that the flagella disintegrated more or less 
completely at the time of observation. 

Pitelka (1949) studied flagella of euglenoid organisms under light 
and electron microscopes. She found that the flagellum of Euglena 


gracilis, Astasia longa and Rhabdomonas incurva, consists of an 
axoneme, composed of about 9 fibrils, 350-600 A in diameter, ar- 
ranged in two compact, parallel bundles, and a sheath which is made 
up of fibrillar elements, a probably semi-fluid matrix and a limiting 
membrane. Under conditions always associated with death of the 
organism, the fibrils of the sheath fray out on one or more sides of 
the flagellum into fine lateral filaments or mastigonemes. The electron 
micrographs obtained by various investigators on supposedly one 
and the same flagellate present a varied appearance of the structure. 
Compare, for example, the micrographs of the frayed flagellum of 
Euglena gracilis by Brown (1945), Pitelka (1949) and Houwink 
(1951). The anterior flagellum of Peranema trichophorum frays out 
into three strands during the course of disintegration as first ob- 
served by Dellinger (1909) and by several recent observers. It can be 
easily demonstrated by treating the organism with reagents such as 
acidified methyl green. Under electron microscope, Petelka noted no 
frayed mastigonemes in the flagellum of Peranema, while Chen 
(1950) observed numerous mastigonemes extending out from all 
sides like a brush, except the basal portion of the flagellum. 

The electron micrographs of the flagellum of trypanosomes reveal 
that it also consists of an axoneme and a sheath of cytoplasm. The 
axoneme is composed of a number of long parallel fibrils, 8 in 
Tnjpanosoma lewisi, each with estimated diameters of 0. 055-0. 06m 
(Kleinschmidt and Kinder, 1950), and up to 9 in T. evansi, with 
estimated diameters of 0.04-0.05^ (Kraneveld, Houwink and Keidel, 
1951). The cytoplasmic sheath of the latter species was said to be 
cross-striated at about 0.05m intervals. No mastigonemes occur in 
these flagella. 

The frayed condition of a flagellum which had become detached 
from the organism or which is still attached to a moribund indi- 
vidual, as revealed by the darkfield microscope, may also indicate a 
phase in disintegration of the flagellum. It is reasonable to assume 
that different flagella may have structural differences as revealed by 
the electron microscope, but evidence for the occurrence of mas- 
tigonemes on an active flagellum of a normally living organism ap- 
pears not to be on hand. 

A flagellum takes its origin in a blepharoplast of kinetosome im- 
bedded in the cytoplasm. The blepharoplast is a small compact 
granule, but in certain parasitic flagellates, it may be comparatively 
large and ovoid or short rod-shaped, surrounded often by a halo. 
Whether this is due to the presence of a delicate cortical structure 
enveloping the compact body or to desiccation or fixation is un- 


known. In such forms, the flagellum appears to arise from the outer 
edge of the halo. Certain observers such as Woodcock (1906), Min- 
chin (1912), etc., used the term kinetonucleus. It has since been 
found that the blepharoplast of certain trypanosomes often gives a 
positive Feulgen's reaction (Bresslau and Scremin, 1924). 

The blepharoplast and centriole are considered synonymous by 
some, since prior to the division of nucleus, it divides and initiates 
the division of the latter. A new flagellum arises from one of the 
daughter blepharoplasts. While the blepharoplast is inseparably 
connected with the flagellum and its activity, it is exceedingly small 
or absent in Trypanosoma equinum and in some strains of T. evansi. 
Furthermore, this condition may be produced by exposure of normal 
individuals to certain chemical substances (Jirovec, 1929; Piekarski, 
1949) or spontaneously (p. 228) without decrease in flagellar activity. 

The flagellum is most frequently inserted near the anterior end 
of the body and directed forward, its movement pulling the organ- 
ism forward. Combined with this, there may be a trailing flagellum 
which is directed posteriorly and serves to steer the course of move- 
ment or to push the body forward to a certain extent. In a compara- 
tively small number of flagellates, the flagellum is inserted near the 
posterior end of the body and would push the body forward by its 
vibration. Under favorable conditions, flagellates regenerate lost 
flagella. For example, Peranema trichophorum from which its an- 
terior flagellum w r as cut off, regenerated a new one in two hours 
(Chen, 1950). 

In certain parasitic Mastigophora, such as Trypanosoma (Fig. 
9), Trichomonas, etc., there is a very delicate membrane extending 
out from the side of the body, a flagellum bordering its outer margin. 
When this membrane vibrates, it shows a characteristic undulating 
movement, as will easily be seen in Trypanosoma rotatorium of the 
frog, and is called the undulating membrane. In many of the dino- 
flagellates, the transverse flagellum seems to be similarly constructed 
(Kofoid and Swezy) (Fig. 127, d,f). 

Cilia. The cilia are the organella of locomotion found in the Cilio- 
phora. They aid in the ingestion of food and serve often as a tactile 
organella. The cilia are fine and more or less short processes of ecto- 
plasm and occur in large numbers in the majority of the Holotricha. 
They may be uniformly long, as in Protociliata, or may be of differ- 
ent lengths, being longer at the extremities, on certain areas, in 
peristome or in circumoral areas. Ordinarily the cilia are arranged in 
longitudinal, oblique, or spiral rows, being inserted either on the 
ridges or in the furrows. A cilium originates in a kinetosome embedded 



in the ectoplasm. In well-studied ciliates, there occurs a fine fibril, 
kinetodesma (Chatton and Lwoff, 1935), a short distance to the right 
of the kinetosome (Fig. 23). The ciliary row or kinety (Chatton and 
Lwoff) consists of the kinetosomes and kinetodesma (Fig. 23, a). In 
forms such as Suctoria in which cilia occur only in the swimming 
stage, the kinetosomes appear to be present as infraciliature (Chat- 
ton, Lwoff and Lwoff, 1929). 





Fig. 9. A diagram showing the structure of a trypanosome (Ktihn). 

As to its structure, a cilium appears to be made up of an axoneme 
and contractile sheath (Fig. 10, a). Gelei observed in flagella and 
cilia, lipoid substance in granular or rod-like forms which differed 
even among different individuals of the same species; and Klein 
(1929) found in many cilia of Colpidium colpoda, an argentophilous 
substance in granular form much resembling the lipoid structure of 
Gelei and called them "cross striation" of the contractile component 
(Fig. 10, b, c). In electron micrographs of a dried cilium of Para- 
mecium, Jakus and Hall (1946) found that it consisted of a bundle of 
about 11 fibrils extending the full length (Fig. 10, d). These fibrils 
were about 300-500 A in diameter. As there was no visible sheath, 
the two observers remarked that if a sheath exists, it must be very 
fragile and easily ruptured. 

The cilia are often present more densely in a certain area than 
in other parts of body and, consequently, such an area stands out 
conspicuously, and is sometimes referred to as a ciliary field. If this 
area is in the form of a zone, it may be called a ciliary zone. Some 
authors use pectinellae for short longitudinal rows or transverse 



bands of close-set cilia. In a number of forms, such as Coleps, Sten- 
tor, etc., there occur, mingled among the vibratile cilia, immobile 
stiff cilia which are apparently solely tactile in function. 

Fig. 10. a, cilia of Coleps; b, cilium of Cyclidium glaucoma; c, basal por- 
tion of a cilium of Colpidium colpoda, all in silver preparations (Klein); d, 
electronmicrograph of a dried cilium of Paramecium, shadow-cast with 
chromium, XI 1,000 (Jakus and Hall). 

In the Hypotricha, the cilia are largely replaced by cirri, although 
in some species both may occur. A cirrus is composed of a number of 
cilia arranged in 2 to 3 rows that fused into one structure com- 
pletely (Figs. 11, a; 12, a), which was demonstrated by Taylor. Klein 
also showed by desiccation that each marginal cirrus of Stylonychia 



was composed of 7 to 8 cilia. In some instances, the distal portion of a 
cirrus may show two or more branches. The cirri are confined to the 
ventral surface in Hypotricha, and called frontal, ventral, anal, 

Cirrus fiber 

Ectoplasmic granules 
Basal plate of the cirrus 

Kinetosomes of 

component cilia 

Adoral zone 
Frontal cirri 
Undulating membrane 

Marginal cirri 
Ventral cirri 

Anal cirri 
Caudal cirri 

Fig. 11. a, five anal cirri of Euplotes eurystomus (Taylo'r); b, schematic 
ventral view of Stylonychia to show the distribution of the cirri. 

caudal, and marginal cirri, according to their location (Fig. 11, b). 
Unlike cilia, the cirri may move in any direction so that the organ- 
isms bearing them show various types of locomotion. Oxytricha, 



Stylonychia, etc., "walk" on frontals, ventrals, and anals, while swim- 
ming movement by other species is of different types. 

In all euciliates except Holotricha, there are adoral membranellae. 
A membranella is composed of a double ciliary lamella, fused com- 
pletely into a plate (Fig. 12, b). A number of these membranellae 
occur on a margin of the peristome, forming the adoral zone of 


Fig. 12. Diagrams of cirrus and membranella of Euplotes eurystomus, 
X1450 (Taylor), a, anal cirrus in side view; b, a membranella (cpg, co- 
agulated protoplasmic granules; cr, ciliary root; fp, fiber plate; k, kineto- 
some) . 

membranellae, which serves for bringing the food particles to the 
cytostome as well as for locomotion. The frontal portion of the zone, 
the so-called frontal membrane appears to serve for locomotion and 
Kahl considers that it is probably made up of three lamellae. The oral 
membranes which are often found in Holotricha and Heterotricha, 
are transparent thin membranous structures composed of one or two 
rows of cilia, which are more or less strongly fused. The membranes, 
located in the lower end of the peristome, are sometimes called 
perioral membranes, and those in the cytopharynx, undulating mem- 

In Suctoria, cilia are present only during the developmental 
stages, and, as the organisms become mature, tentacles develop in 
their stead. The tentacles are concerned with food-capturing, and 



are either prehensile or usually suctorial. The prehensile tentacle 
appears to be essentially similar in structure to the axopodium 
(Roskin, 1925). The suctorial tentacles are tubular and this type is 
interpreted by Collin as possibly derived from cytostome and cyto- 
pharynx of the ciliate (Fig. 13). 

Although the vast majority of Protozoa possess only one of the 
three organelles of locomotion mentioned above, a few may possess 


Fig. 13. Diagrams showing the possible development of a suctorian 
tentacle from a cytostome and cytopharynx of a ciliate (Collin). 

pseudopodia in one stage and flagella in another during their de- 
velopment. Among several examples may be mentioned Naegleri- 
idae (Fig. 183), Tetramitus rostratus (Fig. 155), etc. Furthermore, 
there are some Protozoa which possess two types of organellae at the 
same time. Flagellum or flagella and pseudopodia occur in many 
Phytomastigina and Rhizomastigina, and a flagellum and cilia are 
present in Ileonema (Fig. 306, b, c). 

In the cytoplasm of Protozoa there occur various organellae, each 
of which will be considered here briefly. 

Fibrillar structures 

One of the fundamental characteristics of the protoplasm is its 
contractility. If a fully expanded Amoeba proteus is subjected to a 
mechanical pressure, it retracts its pseudopodia and contracts into a 
more or less spherical form. In this response there is no special or- 
ganella, and the whole body reacts. But in certain other Protozoa, 
there are special organellae of contraction. Many Ciliophora are able 
to contract instantaneously when subjected to mechanical pressure, 
as will easily be noticed by following the movement of Stentor, 
Spirostomum, Trachelocerca, Vorticella, etc., under a dissecting 
microscope. The earliest observer of the contractile elements of 
Protozoa appears to be Lieberkiihn (1857) who noted the "muscle 



fibers" in the ectoplasm of Stentor which were later named 
myonemes (Haeckel) or neurophanes (Neresheimer). 

The myonemes of Stentor have been studied by several in- 
vestigators. According to Schroder (1906), there is a canal between 
each two longitudinal striae and in it occurs a long banded myoneme 
which measures in cross-section 3-7/x high by about lju wide and 
which appears cross-striated (Fig. 14). Roskin (1923) considers that 



Fig. 14. Myonemes in Stentor coeruleus (Schroder), a, cross-section of 
the ectoplasm; b, surface view of three myonemes; c, two isolated 
myonemes (cl, cilium; gis, granules between striae; k, kinetosome; m, 
myoneme; mc, myoneme canal). 

the myoneme is a homogeneous cytoplasm (kinoplasm) and the wall 
of the canal is highly elastic and counteracts the contraction of the 
myonemes. All observers agree that the myoneme is a highly con- 
tractile organella. 

Many stalked peritrichous ciliates have well-developed myonemes 
not only in the body proper, but also in the stalk. Koltzoff's (1911) 
studies show that the stalk is a pseudochitinous tube, enclosing an 
inner tube filled with granulated thecoplasm, which surrounds a cen- 
tral rod, composed of kinoplasm, on the surface of which are ar- 



ranged skeletal fibrils (Fig. 15). The contraction of the stalk is 
brought about by the action of kinoplasm and walls, while elastic 
rods will lead to extension of the stalk. Myonemes present in the 
ciliates aid in the contraction of body, but those which occur in 
many Gregarinida aid apparently in locomotion, being arranged 
longitudinally, transversely and probably spirally (Roskin and 
Levinsohn, 1929) (Fig. 15, c). In certain Radiolaria, such as Acantho- 

Fig. 15. a, b, fibrillar structures of the stalk of Zoothamnium (Kolt- 
zoff); c, myonemes in Gregarina (Schneider), ef, elastic fiber; ie, inner 
envelope; k, kinoplasm; oe, outer envelope; t, thecoplasm. 

metron elasticum (Fig. 219, c), etc., each axial spine is connected with 
10-30 myonemes (myophrisks) originating in the body surface. 
When these myonemes contract, the body volume is increased, thus 
in this case functioning as a hydrostatic organella. 

In Isotricha prostoma and /. intestinalis, Schuberg (1888) observed 
that the nucleus is suspended by ectoplasmic fibrils and called the 
apparatus karyophore. In some forms these fibrils are replaced by 
ectoplasmic membranes as in Nyctotherus ovalis (Zulueta; Kudo), 
ten Kate (1927, 1928) studied fibrillar systems in Opalina, Nycto- 


therus, Ichthyophthirius, Didinium, and Balantidium, and found 
that there are numerous fibrils, each of which originates in the kine- 
tosome of a cilium and takes a transverse or oblique course through 
the endoplasm, ending in a kinetosome located on the other side of 
the body. He further noted that the cytopharynx and nucleus are 
also connected with these fibrils, ten Kate suggested morphonemes 
for them, since he believed that the majority were form-retaining 

The well-coordinated movement of cilia in the ciliate has long 
been recognized, but it was Sharp (1914) who definitely showed that 
this ciliary coordination is made possible by a certain fibrillar system 
which he discovered in Epidinium (Diplodinium) ecaudatum (Fig. 
16). Sharp recognized in this ciliate a complicated fibrillar system 
connecting all the motor organellae of the cytostomal region, and 
thinking that it was "probably nervous in function," as its size, ar- 
rangement and location did not suggest supporting or contractile 
function, he gave the name neuromotor apparatus to the whole 
system. This apparatus consists of a central motor mass, the 
motorium (which is stained red with Zenker fixation and modified 
Mallory's connective tissue staining), located in the ectoplasm just 
above the base of the left skeletal area, from which definite strands 
radiate: namely, one to the roots of the dorsal membranellae (a 
dorsal motor strand) ; one to the roots of the adoral membranellae 
(a ventral motor strand); one to the cytopharynx (a circum-oeso- 
phageal ring and oesophageal fibers) ; and several strands into the 
ectoplasm of the operculum (opercular fibers). A similar apparatus 
has since been observed in many other ciliates: Euplotes (Yocom; 
Taylor), Balantiduum (McDonald), Paramecium (Rees; Brown; 
Lund), Tintinnopsis (Campbell), Boveria (Pickard), Dileptus 
(Visscher), Chlamydodon (MacDougall), Entorhipidium and Le- 
chriopyla (Lynch), Eupoterion (MacLennan and Connell), Metopus 
(Lucas), Troglodytella (Swezey), Oxytricha (Lund), Ancistruma and 
Conchophthirus (Kidder), etc. Ciliate fibrillar systems (Taylor, 

Euplotes, a common free-living hypotrichous ciliate, has been 
known for nearly 60 years to possess definite fibrils connecting the 
anal cirri with the anterior part of the body. Engelmann suggested 
that their function was more or less nervelike, while others main- 
tained that they were supporting or contracting in function. Yocom 
(1918) traced the fibrils to the motorium, a very small bilobed body 
(about 8/x by 2ju) located close to the right anterior corner of the 
triangular cytostome (Fig. 17, m). Joining with its left end are five 

Fig. 16. A composite drawing from three median sagittal sections of 
Epidinium ecaudatum, fixed in Zenker and stained with Mallory's connec- 
tive tissue stain, X1200 (Sharp), am, adoral membranellae; c, cytostome; 
cp, cytopharynx; cpg, cytopyge; cpr, circumpharyngeal ring; dd, dorsal 
disk; dm, dorsal membrane; ec, ectoplasm; en, endoplasm; m, motorium; 
oc, oral cilia; od, oral disk; oef, oesophageal fibers; of, opercular fibers; 
p, pellicle; prs, pharyngeal retractor strands; si, skeletal laminae; vs, ven- 
tral skeletal area. 



long fibers (acf) from the anal cirri which converge and appear to 
unite with the motorium as a single strand. From the right end of the 
motorium extends the membranella-fiber anteriorly and then to left 
along the proximal border of the oral lip and the bases of all mem- 
branellae. Yocom further noticed that within the lip there is a 


Fig. 17. Ventral view of Euplotes eurystomus (E. patella) showing neu- 
romotor system, X670 (Hammond), acf, fibril of anal cirrus; am, anterior 
adoral zone membranelle; m, motorium; mf, membranelle fibrils; oc, en- 
doral cilia; pf, post-pharyngeal fibril; pra, post-pharyngeal membrane; 
rf, radiating fibrils; sm, suboral membranelles; vm, ventral adoral zone 

latticework structure whose bases very closely approximate the cyto- 
stomal fiber. Taylor (1920) recognized two additional groups of 
fibrils in the same organism: (1) membranella fiber plates, each of 
which is contiguous with a membranella basal plate, and is attached 
at one end to the membranella fiber; (2) dissociated fiber plates con- 
tiguous with the basal plates of the frontal, ventral and marginal 
cirri, to each of which are attached the dissociated fibers (rf). By 
means of microdissection needles, Taylor demonstrated that these 


fibers have nothing to do with the maintenance of the body form, 
since there results no deformity when Euplotes is cut fully two- 
thirds its width, thus cutting the fibers, and that when the motorium 
is destroyed or its attached fibers are cut, there is no coordination 
in the movements of the adoral membranellae and anal cirri. Ham- 
mond (1937) and Hammond and Kofoid (1937) find the neuromotor 
system continuous throughout the stages during asexual reproduc- 
tion and conjugation so that functional activity is maintained at all 

A striking feature common to all neuromotor systems, is that 
there seems to be a central motorium from which radiate fibers to 
different ciliary structures and that, at the bases of such motor or- 
ganellae, are found the kinetosomes or basal plates to which the 
"nerve" fibers from the motorium are attached. 

Independent of the studies on the neuromotor system of American 
investigators, Klein (1926) introduced the silver-impregnation 
method which had first been used by Golgi in 1873 to demonstrate 
various fibrillar structures of metazoan cells, to Protozoa in order 
to demonstrate the cortical fibers present in ciliates, by dry-fixation 
and impregnating with silver nitrate. Klein (1926-1942) subjected 
ciliates of numerous genera and species to this method, and observed 
that there was a fibrillar system in the ectoplasm at the level of the 
kinetosomes which could not be demonstrated by other methods. 
Klein (1927) named the fibers silver lines and the whole complex, 
the silverline system, which vary among different species (Figs. 18- 
20). Gelei, Chatton and Lwoff, Jlrovec, Lynch, Jacobson, Kidder. 
Lund, Burt, and others, applied the silver-impregnation method to 
many other ciliates and confirmed Klein's observations. Chatton and 
Lwoff (1935) found in Apostomea, the system remains even after the 
embryonic cilia have entirely disappeared and considered it in- 

The question whether the neuromotor apparatus and the silver- 
line system are independent structures or different aspects of the 
same structure has been raised frequently. Turner (1933) found that 
in Euplotes patella (E. eurystomus) the silverline system is a regular 
latticework on the dorsal surface and a more irregular network on 
the ventral surface. These lines are associated with rows of rosettes 
from which bristles extend. These bristles are held to be sensory in 
function and the network, a sensory conductor system, which is 
connected with the neuromotor system. Turner maintains that the 
neuromotor apparatus in Euplotes is augmented by a distinct but 
connected external network of sensory fibrils. He however finds no 
motorium in this protozoan. 



Lund (1933) also made a comparative study of the two systems 
in Paramecium multimicronucleatum, and observed that the silverline 
system of this ciliate consists of two parts. One portion is made up 
of a series of closely-set polygons, usually hexagons, but flattened 
into rhomboids or other quadrilaterals in the regions of the cyto- 
stome, cytopyge, and suture. This system of lines stains if the or- 

Fig. 18. The silverline system of Ancistruma mytili, XlOOO (Kidder). 
a, ventral view; b, dorsal view. 

ganisms are well dried. Usually the lines appear solid, but fre- 
quently they are interrupted to appear double at the vertices of the 
polygons which Klein called "indirectly connected" (pellicular) 
conductile system. In the middle of the anterior and posterior sides 
of the hexagons is found one granule or a cluster of 2-4 granules, 
which marks the outer end of the trichocyst. The second part which 
Klein called "directly connected" (subpellicular) conductile system 
consists essentially of the longitudinal lines connecting all kine- 
tosomes in a longitudinal row of hexagons and of delicate transverse 
fibrils connecting granules of adjacent rows especially in the cyto- 
stomal region (Fig. 19). 

By using Sharp's technique, Lund found the neuromotor system 



of Paramecium multimicronucleatum constructed as follows: The 
subpellicular portion of the system is the longitudinal fibrils which 
connect the kinetosomes. In the cytostomal region, the fibrils of 
right and left sides curve inward forming complete circuits (the 
circular cytostomal fibrils) (Fig. 20). The postoral suture is separated 
at the point where the cytopyge is situated. Usually 40-50 fibrils 

Fig. 19. Diagram of the cortical region of Paramecium multimicronu- 
cleatum, showing various organellae (Lund), c, cilia; et, tip of trichocyst; 
k, kinetosome; If, longitudinal fibril; p, pellicle; t, trichocyst; tf, transverse 

radiate outward from the cytostome (the radial cytostomal fibrils). 
The pharyngeal portion is more complex and consists of (1) the 
oesophageal network, (2) the motorium and associated fibrils, (3) 
penniculus which is composed of 8 rows of kinetosomes, thus form- 
ing a heavy band of cilia in the cytopharynx, (4) oesophageal process, 
(5) paraoesophageal fibrils, (6) posterior neuromotor chain, and (7) 
postoesophageal fibrils. Lund concludes that the so-called silverline 
system includes three structures: namely, the peculiarly ridged 
pellicle; trichocysts which have no fibrillar connections among 
them or with fibrils, hence not conductile; and the subpellicular sys- 
tem, the last of which is that part of the neuromotor system that 
concerns with the body cilia, ten Kate (1927) suggested that senso- 
motor apparatus is a better term than the neuromotor apparatus. 
Silverline system (Klein, 1926-1942; Gelei, 1932); fibrils in ciliates 

Fig. 20. The neuromotor system of Paramecium multimicronucleahim 
(Lund), a, oral network; b, motorium, X1670. aep, anterior end of pen- 
niculus; c, cytopyge; ccf, circular cytostomal fibril; cof, circular oesopha- 
geal fibril; cpf, circular pharyngeal fibril; ef, endoplasmic fibrils; lbf, 
longitudinal body fibril; lof, longitudinal oesophageal fibrils; lpf, longi- 
tudinal pharyngeal fibril; m, motorium; oo, opening of oesophagus; op, 
oesophageal process; paf, paraoesophageal fibrils; pep, posterior end of 
penniculus; pnc, posterior neuromotor chain; pof, postoesophageal fibrils; 
rcf, radial cytostomal fibril; s, suture. 


(Jacobson, 1932; Taylor, 1941); argyrome in Astomata (Puytorac, 

Protective or supportive organ ellae 

The external structures as found among various Protozoa which 
serve for body protection, have already been considered (p. 47). 
Here certain internal structures will be discussed. The greater part 
of the shell of Foraminifera is to be looked upon as endoskeleton 
and thus supportive in function. In Radiolaria, there is a mem- 
branous structure, the central capsule, which divides the body into 
a central region and a peripheral zone. The intracapsular portion 
contains the nucleus or nuclei, and is the seat of reproductive proc- 
esses, and thus the capsule is to be considered as a protective or- 
ganella. The skeletal structures of Radiolaria vary in chemical com- 
position and forms, and are arranged with a remarkable regularity 
(p. 517). 

In some of the astomatous euciliates, there are certain structures 
which seem to serve for attaching the body to the host's organ, but 
which seem to be supportive to a certain extent also. The peculiar 
organella furcula, observed by Lynch in Lechriopyla (p. 741) is said 
to be concerned with either the neuromotor system or protection. 
The members of the family Ophryoscolecidae (p. 816), which are 
common commensals in the stomach of ruminants, have conspicuous 
endoskeletal plates which arise in the oral region and extend posteri- 
orly. Dogiel (1923) believed that the skeletal plates of Cycloposthium 
and Ophryoscolecidae are made up of hemicellulose, "ophryoscole- 
cin," which was also observed by Strelkow (1929). MacLennan 
found that the skeletal plates of Polyplastron multivesiculatum were 
composed of small, roughly prismatic blocks of paraglycogen, each 
possessing a central granule. 

In certain Polymastigina and Hypermastigina, there occurs a 
flexible structure known as the axostyle, which varies from a fila- 
mentous structure as in several Trichomonas, to a very conspicuous 
rod-like structure occurring in Parajoenia, Gigantomonas, etc. The 
anterior end of the axostyle is very close to the anterior tip of the 
body, and it extends lengthwise through the cytoplasm, ending near 
the posterior end or extending beyond the body surface. In other 
cases, the axostyle is replaced by a bundle of axostylar filaments 
that are connected with the flagella (Lophomonas). The axostyle 
appears to be supportive in function, but in forms such as Saccino- 
baculus, it undulates and aids in locomotion (p. 379). 

In trichomonad flagellates there is often present along the line of 


attachment of the undulating membrane, a rod-like structure which 
has been known as costa (Kunstler) and which, according to Kirby's 
extensive study, appears to be most highly developed in Pseudo- 
trypanosoma and Trichomonas. The staining reaction indicates that 
its chemical composition is different from that of flagella, blepharo- 
plast, parabasal body, or chromatin. 

In the gymnostomatous ciliates, the cytopharynx is often sur- 
rounded by rod-like bodies, and the entire apparatus is often called 
oral or pharyngeal basket, which is considered as supportive in 
function. These rods are arranged to form the wall of the cyto- 
pharynx in a characteristic way. For example, the oral basket of 
Chilodonella cucullulus (Fig. 312, c, d) is made up of 12 long rods 
which are so completely fused in part that it appears to be a smooth 
tube; in other forms, the rods are evidently similar to the tubular 
trichocysts or trichites mentioned below. 

In numerous holotrichs, there occur unique organelles, trichocysts, 
imbedded in the ectoplasm, and usually arranged at right angles to 
the body surface, though in forms such as Cyclogramma, they are 
arranged obliquely. Under certain stimulations, the trichocysts "ex- 
plode" and form long filaments which extend out into the surround- 
ing medium. The shape of the trichocyst varies somewhat among 
different ciliates,, being pyriform, fusiform or cylindrical (Penard, 
1922; Kriiger, 1936). They appear as homogeneous refractile bodies. 
The extrusion of the trichocyst is easily brought about by means of 
mechanical pressure or of chemical (acid or alkaline) stimulation. 

In forms such as Paramecium, Frontonia, etc., the trichocyst is 
elongate pyriform or fusiform. It is supposed that within an expansi- 
ble membrane, there is a layer of swelling body which is responsible 
for the remarkable longitudinal extension of the membrane (Kriiger) 
(Fig. 21, a). In other forms such as Prorodon, Didinium, etc., the 
tubular trichocyst or trichites are cylindrical in shape and the mem- 
brane is a thick capsule with a coiled thread, and when stimulated, 
the extrusion of the thread takes place. The trichites of Prorodon 
teres measure about 10—1 1 yu. long (Fig. 21, d) and when extruded, 
the whole measures about 20 /x; those of Didinium nasutum are 15- 
20m long and after extrusion, measure about 40 m in length (Fig. 21, 
e,f). In Spathidium spathida (Fig. 21, c), trichites are imbedded like 
a paling in the thickened rim of the anterior end. They are also 
distributed throughout the endoplasm and, according to Woodruff 
and Spencer, "some of these are apparently newly formed and being- 
transported to the oral region, while others may well be trichites 
which have been torn away during the process of prey ingestion, " 



Fig. 21. a, a schematic drawing of the trichocyst of Paramecium cau- 
datum (Kruger) (b, base of the tip; c, cap; m, membrane; mt, membrane 
of extruded trichocyst; s, swelling body; t, tip); b, an extruded trichocyst, 
viewed under phase dark contrast, X1800; c, trichites in Spathidium, 
spathula, X300 (Woodruff and Spencer); d, a diagram of the trichocyst of 
Prorodon teres (Kruger) (eg, capsule-granule; e, end-piece of filament; f, 
filament; w, capsule wall); e, f, normal and extruded trichocysts of Didin- 
ium nasutum (Kruger). 


Whether the numerous 12-20^ long needle-like structures which 
Kahl observed in Remanella (p. 727) are modified trichites or not, 
is not known. 

Dileptus anser feeds on various ciliates through the cytostome, 
located at the base of the proboscis, which possesses a band of long 
trichocysts on its ventral side. When food organisms come in contact 
with the ventral side of the proboscis, they give a violent jerk, and 
remain motionless. Visscher saw no formed elements discharged 
from the trichocysts, and, therefore, considered that these tricho- 
cysts contained a toxic fluid and named them toxicysts. But Kruger 
and Hayes (1938) found that the extruded trichocysts can be recog- 

Perhaps the most frequently studied trichocysts are those of 
Paramecium. They are elongate pyriform, with a fine tip at the 
broad end facing the body surface. The tip is connected with the 
pellicle (Fig. 19, 0- Kruger found this tip is covered by a cap (Fig. 
21, a) which can be seen under darkfield or phase microscope and 
which was demonstrated by Jakus (1945) in an electron micrograph 
(Fig. 22, a). When extruded violently, the entire structure is to be 
found outside the body of Paramecium. The extruded trichocyst is 
composed of two parts: the tip and the main body (Fig. 21, b). The 
tip is a small inverted tack, and may be straight, curved or bent. 
The main body or shaft is a straight rod, tapering gradually into a 
sharp point at the end opposite the tip. Extruded trichocysts meas- 
ure 20-40yu or more in length, and do not show any visible struc- 
tures, except a highly refractile granule present at the base of the 
tuck-shaped tip (Fig. 21, b). The electron microscope studies of the 
extruded trichocysts by Jakus (1945), Jakus and Hall (1946) and 
Wohlfarth-Bottermann (1950), show the shaft to be cross-striated 
(Fig. 22). Jakus considers that the main component of the tricho- 
cyst is a thin cylindrical membrane formed by close packing of 
longitudinal fibrils characterized by a periodic pattern (somewhat 
resembling that of collagen), and as the fibrils are in phase with re- 
spect to this pattern, the membrane appears cross-striated. 

As to the mechanism of the extrusion, no precise information is 
available, though all observers agree that the contents of the tricho- 
cyst suddenly increase in volume. Kruger maintains that the tricho- 
cyst cap is first lifted and the swelling body increases enormously in 
volume by absorbing water and lengthwise extension takes place, 
while Jakus is inclined to think that the membrane itself extends by 
the sudden uptake of water. 



How are these organelles formed? Tonniges (1914) believes that 
the trichocysts of Frontonia leucas originate in the endosomes of the 
macronucleus and development takes place during their migration 
to the ectoplasm. Brodsky (1924) holds that the trichocyst is com- 
posed of colloidal excretory substances and is first formed in the 
vicinity of the macronucleus. Chatton and Lwoff (1935) find how- 

Fig. 22. Electronmicrographs of extruded trichocysts of Paramecium, 
a, dried and stained with phosphotungstic acid, XI 1,000 (Jakus); b, a 
similarly treated one, X 15,000 (Jakus); c, shadow-cast with chromium, 
X 16,000 (Jakus and Hall). 

ever in Gymnodinioides the trichocysts are formed only in tomite 
stage and each trichocyst arises from a trichocystosome, a granule 
formed by division of a kinetosome (Fig. 23, a-c). In Polyspira, the 
trichocyst formation is not confined to one phase, each kinetosome 
is said to give rise to two granules, one of which may detach itself, 
migrate into other part of the body and develops into a trichocyst 
(d). In Foettingeria, the kinetosomes divide in young trophont stage 
into irichitosomes which develop into trichites (e). The two authors 
note that normally cilia-producing kinetosomes may give rise to 



trichocysts or trichites, depending upon their position (or environ- 
ment) and the phase of development of the organism. 

Although the trichocyst was first discovered by Ellis (1769) 
and so named by Allman (1855), nothing concrete is yet known as 
to their function. Ordinarily the trichocysts are considered as a de- 
fensive organella as in the case of the oft-quoted example Parame- 
cium, but, as Mast demonstrated, the extruded trichocysts of this 
ciliate do not have any effect upon Didinium other than forming a 
viscid mass about the former to hamper the latter. On the other 

Fig. 23. Diagrams showing the formation of trichocysts in Gymnodini- 
oides (a-c) and in Polyspira (d) and of trichites in Foettingeria (e) (Chat- 
ton and Lwoff). a, a ciliary row, composed of kinetosomes, large satellite 
corpuscles and kinetodesma (a solid line); b, each kinetosome divides into 
two, producing trichocystosome; c, transformation of trichocystosomes 
into trichocysts; d, formation of trichocyst from one of the two division 
products of kinetosome; e, formation of trichites from the division prod- 
ucts of kinetosomes. 

hand, the trichocysts and trichites are clearly an offensive organelle 
in capturing food organisms in organisms such as Dileptus, Didinium, 
Spathidium, etc. Saunders (1925) considered that the extruded tri- 
chocysts of Paramecium serve for attachment of the body to other 
objects. But Wohlfarth-Bottermann (1950) saw Paramecium cauda- 
tum extruding up to 300 trichocysts without any apparent external 
stimulation and trichocyst-less individuals were able to adhere to 
foreign objects. This worker suggested that the trichocyst secretes 
calcium salt and probably also sodium and potassium, and thus may 
serve an osmoregulatory function. Some years ago Penard (1922) 
considered that some trichocysts may be secretory organellae to pro- 
duce material for loricae or envelope, with which view Kahl concurs, 
as granular to rod-shaped trichocysts occur in Metopus, Amphilep- 


tus, etc. Klein has called these ectoplasmic granules protrichocysts, 
and in Prorodon, Kruger observed, besides typical tubular tricho- 
cysts, torpedo-like forms to which he applied the same name. To 
this group may belong the trichocysts recognized by Kidder in Con- 
chophthirus mytili. The trichocysts present in certain Cryptomonad- 
ina (Chilomonas and Cyathomonas) are probably homologous with 
the protrichocysts (Kruger, 1934; Hollande, 1942; Dragesco, 1951). 

Hold-fast organellae 

In the Mastigophora, Ciliophora, and a few Sarcodina, there 
are forms which possess a stalk supporting the body or the lorica. 
With the stalk the organism is attached to a solid surface. In some 
cases, as in Ahthophysis, Maryna, etc., the dendritic stalks are 
made up of gelatinous substances rich in iron, which gives to them a 
reddish brown color. In parasitic Protozoa, there are special or- 
ganellae developed for attachment. Many genera of cephaline 
gregarines are provided with an epimerite of different structures 
(Figs. 235-237), by which the organisms are able to attach them- 
selves to the gut epithelium of the host. In Astomata, such as Into- 
shellina, Maupasella, Lachmannella, etc., simple or complex pro- 
trusible chitinous structures are often present in the anterior region ; 
or a certain area of the body may be concave and serves for ad- 
hesion to the host, as in Rhizocaryum, Perezella, etc.; or, again, 
there may be a distinctive sucker-like organella near the anterior 
extremity of the body, as in Haptophyra, Steinella, etc. A sucker is 
also present on the antero-ventral part of Giardia intestinalis. 

In the Myxosporidia and Actinomyxidia, there appear, during 
the development of spore, 1-4 special cells which develop into 
polar capsules, each, when fully formed, enclosing a more or less 
long spirally coiled delicate thread, the polar filament (Figs. 279, 
286). The polar filament is considered as a temporary anchoring or- 
ganella of the spore at the time of its germination after it gained 
entrance into the alimentary canal of a suitable host. In the Micro- 
sporidia, the filament may or may not be enclosed within a capsule 
(Figs. 288; 289). The nematocysts (Fig. 132, b) of certain dino- 
flagellates belonging to Nematoidium and Polykrikos, are almost 
identical in structure with those found in the coelenterates. They 
are distributed through the cytoplasm, and various developmental 
stages were noticed by Chatton, and Kofoid and Swezy, which indi- 
cates that they are characteristic structures of these dinoflagellates 
and not foreign in origin as had been held by some. The function of 
the nematocysts in these protozoans is not understood. 



Parabasal apparatus 

In the cytoplasm of many parasitic flagellates, there is frequently 
present a conspicuous structure known as the parabasal apparatus 
(Janicki, 1911), consisting of the parabasal body and often thread 
(Cleveland), which latter may be absent in some cases. This struc- 
ture varies greatly among different genera and species in appearance, 
structure and position within the body. It is usually connected with 

Fig. 24. Parabasal apparatus in: a, Lophomonas blattarujn (Kudo); 
b, Metadevescovina debilis; c, Devescovina sp. (Kirby). af, axostylar fila- 
ments; bl, blepharoplasts; f, food particles; fl, flagella; n, nucleus; pa, 
parabasal apparatus. 

the blepharoplast and located very close to the nucleus, though 
not directly connected with it. It may be single, double, or multiple, 
and may be pyriform, straight or curved rod-like, bandform, spirally 
coiled or collar-like (Fig. 24). Kofoid and Swezy considered that the 
parabasal body is derived from the nuclear chromatin, varies in 
size according to the metabolic demands of the organism, and is a 
"kinetic reservoir." On the other hand, Duboscq and Grasse" (1933) 
maintain that this body is the Golgi apparatus, since (1) acetic acid 
destroys both the parabasal body and the Golgi apparatus ; (2) both 
are demonstrable with the same technique; (3) the parabasal body 


is made up of chromophile and chromophobe parts as is the Golgi 
apparatus; and (4) there is a strong evidence that the parabasal 
body is secretory in function. According to Kirby (1931), who has 
made an extensive study of this organella, the parabasal body could 
be stained with Delafield's haematoxylin or Mallory's triple stain 
after fixation with acetic acid-containing fixatives and the body does 
not show any evidence to indicate that it is a secretory organella. 
Moreover the parabasal body is discarded or absorbed at the time of 
division of the body and two new ones are formed. 

The parabasal body of Lophomonas blattarum is discarded when 
the organism divides and two new ones are reformed from the cen- 
triole or blepharoplast (Fig. 65), and its function appears to be sup- 
portive. Possibly not all so-called parabasal bodies are homologous 
or analogous. A fuller comprehension of the structure and function 
of the organella rests on further investigations. 

Golgi apparatus 

With the discovery of a wide distribution of the so-called Golgi 
apparatus in metazoan cells, a number of protozoologists also re- 
ported a homologous structure from many protozoans. It seems im- 
possible at present to indicate just exactly what the Golgi appara- 
tus is, since the so-called Golgi techniques, the important ones of 
which are based upon the assumption that the Golgi material is 
osmiophile and argentophile, and possesses a strong affinity to 
neutral red, are not specific and the results obtained by using the 
same method often vary a great deal. Some of the examples of the 
Golgi apparatus reported from Protozoa are summarized in Table 2. 

It appears thus that the Golgi bodies occurring in Protozoa are 
small osmiophilic granules or larger spherules which are composed 
of osmiophile cortical and osmiophobe central substances. Fre- 
quently the cortical layer is of unequal thickness, and, therefore, 
crescentic forms appear. Ringform apparatus was noted in Chilo- 
donella and Dogielella by Nassonov (1925) and network-like forms 
were observed by Brown in Pyrsonympha and Dinenympha. The 
Golgi apparatus of Protozoa as well as of Metazoa appears to be 
composed of a lipoidal material in combination with protein sub- 

In line with the suggestion made for the metazoan cell, the Golgi 
apparatus of Protozoa is considered as having something to do with 
secretion or excretion. Nassonov (1924) considers that osmiophilic 
lipoidal substance, which he observed in the vicinity of the walls of 
the contractile vacuole and its collecting canals in many ciliates and 

Table 2. — Golgi apparatus in Protozoa 



Golgi apparatus 


Chromulina, Astasia 

Rings, spherules with a dark 



Granules, vacuoles 





Euglena gracilis 

Spherical, discoidal with 
dark rim; tend to group 
around or near nucleus 



Rings, globules, granules 


Pyrsonympha, Di- 

Rings, crescents, spherules; 



granules break down to 
form network near pos- 
terior end 

Holomastigotes, Pyr- 

Parabasal bodies 

Dubocsq and 

sonympha, etc. 


Amoeba proteus (Fig. 

Rings, crescents, globules, 




Endamoeba blattae 

Spheres, rings, crescents 


Monocystis, Gregarina 

Spheres, rings, crescents 


Aggregata, gregarines 

Crescents, rings 



Crescents, beaded grains 

King and 

Blepharisma undidans 

Rings in the cytoplasm 


Vorticella, Lionotus, 

The membrane of contrac- 


Paramecium, Dogiel- 

tile vacuole and collecting 

ella, Nassula, Chilo- 


monas, Chilodonella 

flagellates, is homologous with the metazoan Golgi apparatus and 
secretes the fluid waste material into the vacuole from which it is 
excreted to the exterior. According to Brown, there is no blackening 
by osmic impregnation of the contractile vacuole in Amoeba proteus, 
(Fig. 25), but fusion of minute vacuoles associated with crescentic 
Golgi bodies produces the vacuole and Park (1929) noted osmiophile 
knob-like elevations on the surface of the macronucleus of Stentor 
and Leucophrys, while the contractile vacuole system did not 

Duboscq and Grasse (1933) maintain that this body is a source of 
energy which is utilized by motor organelles. Joyet-Lavergne points 
out that in certain Sporozoa, the Golgi body is composed of granules 
and may be the center of enzyme production. Similar to Golgi ma- 
terial, the so-called vacuome, which consists of neutral red-staining 
and osmiophile globules, has been reported to occur in many Proto- 



zoa (Hall, 1931; Hall and Nigrelli, 1937). The exact morphological 
and physiological significance of these organellae and the relation 
between them must be looked for in future investigations. Golgi 
apparatus in Protozoa (Alexeieff, 1928; MacLennan, 1941; Grasse\ 


Widely distributed in many metazoan cells, the chondriosomes 
have also been recognized in various Protozoa. The chondriosomes 
possess a low refractive index, and are composed of substances easily 


Fig. 25. The Golgi bodies in Amoeba proteus (Brown). 

soluble in alcohol, acetic acid, etc. Osmium tetroxide blackens the 
chondriosomes, but the color bleaches faster than in the Golgi bodies. 
Janus green B stains them even in 1 : 500,000 solution, but stains also 
other inclusions, such as the Golgi bodies (in some cases) and certain 
bacteria. According to Horning (1926), janus red is said to be a more 
exclusive chondriosome stain, as it does not stain bacteria. The 
chemical composition of the chondriosome seems to be somewhat 
similar to that of the Golgi body; namely, it is a protein compounded 
with a lipoidal substance. If the protein is small in amount, it is 
said to be unstable and easily attacked by reagents; on the other 
hand, if the protein is relatively abundant, it is more stable and 
resistant to reagents. 

The chondriosomes occur as small spherical to oval granules, rod- 



like or filamentous bodies, and show a tendency to adhere to or re- 
main near protoplasmic surfaces. In many cases they are distributed 
without any definite order; in others, as in Paramecium or Opalina, 
they are regularly arranged between the kinetosomes of cilia (Hor- 
ning). In Tillina canalifera, Turner (1940) noticed that the endo- 
plasmic chondriosomes are evenly distributed throughout the cyto- 
plasm (Fig. 26, b), while the ectoplasmic chondriosomes are ar- 

Sic. < x 

v } r 


b m^' 

Fig. 26. Chondriosomes in Tillina canalifera (Turner), a, diagram show- 
ing the ectoplasmic chondriosomes (c, cilium; cf, coordinating fibril; ch, 
chondriosome; cr, ciliary rootlet; k, kinetosome I and II; p, pellicle); b, a 
section showing chondriosomes and food vacuoles. 

ranged in regular cross rows, one in the center of each square formed 
by four cilia (Fig. 2f6, a). In Peranema trichophorum, Hall (1929) ob- 
served peripheral chondriosomes located along the spiral striae, 
which Chadefaud (1938) considered as mucus bodies. Weisz (1949, 
1950) finds that stentorin and zoopurpurin already mentioned (p. 
45) are chondriosomes. 

In certain Protozoa, the chondriosomes are not always demon- 
strable. For example, Horning states in Monocystis the chondrio- 
somes present throughout the asexual life-cycle as rod-shaped bodies, 
but at the beginning of the spore formation they decrease in size and 
number, and in the spore none exists. The chondriosomes appear as 
soon as the sporozoites are set free. Thus it would appear that the 


chondriosomes are reformed de novo. On the other hand, Faure- 
Fremiet, the first student of the chondriosomes in Protozoa, main- 
tained that they reproduce by division, which has since been con- 
firmed by many observers. As a matter of fact, Horning found in 
Opalina, the chondriosomes are twisted filamentous structures and 
undergo multiple longitudinal fission in asexual division phase. Be- 
fore encystment, the chondriosomes divide repeatedly transversel}' 
and become spherical bodies which persist during encystment and 
in the gametes. In zygotes, these spherical bodies fuse to produce 
longer forms which break up into elongate filamentous structures. 
Richardson and Horning further succeeded in bringing about divi- 
sion of the chondriosomes in Opalina by changing pH of the medium. 

As to the function of chondriosomes, opinions vary. A number of 
observers hold that they are concerned with the digestive process. 
After studying the relationship between the chondriosomes and 
food vacuoles of Amoeba and Paramecium, Horning suggested that 
the chondriosomes are the seat of enzyme activity and it is even 
probable that they actually give up their own substance for this 
purpose. Mast (1926) described "beta granules" in Amoeba proteus 
which are more abundantly found around the contractile vacuole. 
Mast and Doyle (1935, 1935a) noted that these spherical to rod-like 
beta granules are plastic and stain like chondriosomes and that there 
is a direct relation between the number of beta granules in the cyto- 
plasm and the frequency of contraction of the contractile vacuole. 
They maintained that these granules "probably function in trans- 
ferring substances from place to place in the cytoplasm." Similar 
granules are recognizable in the species of Pelomyxa (Andresen, 
1942; Wilber, 1942; Kudo, 1951). 

The view that the chondriosomes may have something to do with 
the cell-respiration expressed by Kingsbury was further elaborated 
by Joyet-Lavergne through his studies on certain Sporozoa. That 
the chondriosomes are actively concerned with the development of 
the gametes of the Metazoa is well known. Zweibaum's observation, 
showing an increase in the amount of fatty acid in Paramecium just 
prior to conjugation, appears to suggest this function. On the other 
hand, Calkins found that in Uroleptus, the chondriosomes became 
abundant in exconjugants, due to transformation of the macronu- 
clear material into the chondriosomes. The author agrees with 
McBride and Hewer who wrote: "it is a remarkable thing that so 
little is known positively about one of the 'best known' protoplasmic 
inclusions" (Piney, 1931). Condriosomes in Protozoa (MacLennan, 
1941; Grasse, 1952). 


Numerous minute granules, less than l^u in diameter, occur usually 
abundantly suspended in the cytoplasm. They can most clearly be 
noted under phase microscope. Mast named those found in Amoeba 
"alpha granules." 

Contractile and other vacuoles 

The majority of Protozoa possess one or more vacuoles known 
as pulsating or contractile vacuoles. They occur regularly in all 
freshwater-inhabiting Sarcodina, Mastigophora and Ciliophora. Ma- 
rine or parasitic Sarcodina and Mastigophora do not ordinarily have 
a contractile vacuole. This organelle is present with a few exceptions 
in all marine and parasitic Ciliophora, while it is wholly absent in 

In various species of free-living amoebae, the contractile vacuole 
is formed by accumulation of water in one or more droplets which 
finally fuse into one. It enlarges itself continuously until it reaches 
a maximum size (diastole) and suddenly bursts through the thin 
cytoplasmic layer above it (systole), discharging its content to out- 
side. The location of the vacuole is not definite in such forms and, 
therefore, it moves about with the cytoplasmic movements; and, as 
a rule, it is confined to the temporary posterior region of the body. 
Although almost spherical in form, it may occasionally be irregular 
in shape, as in Amoeba striata (Fig. 184, /). In many testaceans and 
heliozoans, the contractile vacuoles which are variable in number, 
are formed in the ectoplasm and the body surface bulges out above 
the vacuoles at diastole. In Mastigophora, the contractile vacuole 
appears to be located in the anterior region. 

In the Ciliophora, except Protociliata, there occur one to many 
contractile vacuoles, which seem to be located in the deepest part 
of the ectoplasm and therefore constant in position. Directly above 
each vacuole is found a pore in the pellicle, through which the con- 
tent of the vacuole is discharged to outside. In the species of Con- 
chophthirus, Kidder (1934) observed a narrow slit in the pellicle 
just posterior to the vacuole on the dorsal surface (Fig. 27). The 
margin of the slit is thickened and highly refractile. During diastole, 
the slit is nearly closed and, at systole, the wall of the contractile 
vacuole appears to break and the slit opens suddenly, the vacuolar 
content pouring out slowly. When there is only one contractile 
vacuole, it is usually located either near the cytopharynx or, more 
often, in the posterior part of the body. When several to many 
vacuoles are present, they may be distributed without apparent 
order, in linear series, or along the body outline. When the contrac- 


tile vacuoles are deeply seated, there is a delicate duct which con- 
nects the vacuole with the pore on the pellicle as in Paramecium 
woodruffi, or in Ophryoscolecidae. In Balantidium, Nyctotherus, etc., 
the contractile vacuole is formed very close to the permanent cyto- 
pyge located at the posterior extremity, through which it empties its 

In a number of ciliates there occur radiating or collecting canals 
besides the main contractile vacuole. These canals radiate from the 
central vacuole in Paramecium, Frontonia, Disematostoma, etc. But 
when the vacuole is terminal, the collecting canals of course do not 
radiate, in which case the number of the canals varies among 
different species: one in Spirostomum, Stentor, etc., 2 in Clima- 


i : 


Fig. 27. Diagrams showing the contractile vacuole, the accessory vacu- 
oles and the aperture, during diastole and systole in Conchophthirus 

costomum, Eschaneustyla, etc., and several in Tillina. In Peritricha, 
the contractile vacuole occurs near the posterior region of the cyto- 
pharynx and its content is discharged through a canal into the vesti- 
bule and in Ophrydium ectatum, the contractile vacuole empties its 
content into the cytopharynx through a long duct (Mast). 

Of numerous observations concerning the operation of the con- 
tractile vacuole, that of King (1935) on Paramecium multimicro- 
nucleatum (Figs. 28, 29) may be quoted here. In this ciliate, there 
are 2 to 7 contractile vacuoles which are located below the ecto- 
plasm on the aboral side. There is a permanent pore above each 
vacuole. Leading to the pore is a short tube-like invagination of the 
pellicle, with inner end of which the temporary membrane of the 
vacuole is in contact (Fig. 28, a). Each vacuole has 5-10 long col- 
lecting canals with strongly osmiophilic walls (Fig. 29), in which 
Gelei (1939) demonstrated longitudinal fibrils, and each canal is 
made up of terminal portion, a proximal injection canal, and an 
ampulla between them. Surrounding the distal portion, there is osmi- 
ophilic cytoplasm which may be granulated or finely reticulated, and 



which Nassonov (1924) interpreted as homologous with the Golgi 
apparatus of the metazoan cell. The injection canal extends up to 
the pore. The ampulla becomes distended first with fluid transported 
discontinuously down the canal and the fluid next moves into the 
injection canal. The fluid now is expelled into the cytoplasm just 
beneath the pore as a vesicle, the membrane of which is derived 
from that which closed the end of the injection canal. These fluid 

060 <A> 

<3^=> _i^_ _ £5= 

Fig. 28. Diagrams showing the successive stages in the formation of 
the contractile vacuole in Paramecium multimicronucleatum (King) ; up- 
per figures are side views; lower figures front views; solid lines indicate 
permanent structures; dotted lines temporary structures, a, full diastole; 
b-d, stages of systole; e, content of ampulla passing into injection canal; 
f, formation of vesicles from injection canals; g, fusion of vesicles to form 
contractile vacuole; h, full diastole. 

vesicles coalesce presently to form the contractile vacuole in full 
diastole and the fluid is discharged to exterior through the pore, 
which becomes closed by the remains of the membrane of the dis- 
charged vacuole. 

In Haptophrya michiganensis, MacLennan (1944) observed that 
accessory vacuoles appear in the wall of the contractile canal which 
extends along the dorsal side from the sucker to the posterior end, 
as the canal contracts (Fig. 30) . The canal wall expands and enlarg- 
ing accessory vacuoles fuse with one another, followed by a full ex- 
pansion of the canal. Through several excretory pores with short 
ducts the content of the contractile canal is excreted to the exterior. 
The function of the contractile vacuole is considered in the following 



Fig. 29. Contractile vacuoles of Paramecium multimicronucleatum, 
X1200 (King), a, early systole, side view; b, diastole, front view; c, com- 
plete systole, front view; d, systole, side view. 



chapter (p. 118). Comparative study of contractile vacuoles (Haye, 
1930; Weatherby, 1941). 

Various other vacuoles or vesicles occur in different Protozoa. In 
the ciliates belonging to Loxodidae, there are variable numbers of 
Miiller's vesicles or bodies, arranged in 1-2 rows along the aboral sur- 
face. These vesicles (Fig. 31, a-c) vary in diameter from 5 to 8.5/* 

Fig. 30. Excretory canal of Haptophrya michiganensis (MacLennan). 

a, an individual in side view, showing a contraction wave passing down 
the canal; b, successive views of the same region of the contractile canal 
during a full pulsatory cycle (a-c, systole; d-g, diastole); c, diagram show- 
ing a contractile wave passing from left to right between two adjacent 
excretory pores. 

and contain a clear fluid in which one large spherule or several small 
highly refractile spherules are suspended. In some, there is a fila- 
mentous connection between the spherules and the wall of the 
vesicle. Penard maintains that these bodies are balancing cell-organs 
and called the vesicle, the statocyst, and the spherules, the stato- 

Another vacuole, known as concrement vacuole, is a character- 
istic organella in Biitschliidae and Paraisotrichidae. As a rule, there 
is a single vacuole present in an individual in the anterior third of 
body. It is spherical to oval and its structure appears to be highly 



complex. According to Dogiel (1929), the vacuole is composed of a 
pellicular cap, a permanent vacuolar wall, concrement grains and 
two fibrillar systems (Fig. 31, d). When the organism divides, the an- 
terior daughter individual retains it, and the posterior individual de- 
velopes a new one from the pellicle into which concrement grains 

Fig. 31. a-c, Miiller's vesicles in Loxodes (a, b) and in Remanella (c) 
(a, Penard; b, c, Kahl); d, concrement vacuole of Blepharoprosthium 
(Dogiel). cf, centripetal fibril; eg, concrement grains; cp, cap; fw, fibrils 
of wall; p, pellicle; vp, vacuolar pore; w, wall. 

enter after first appearing in the endoplasm. This vacuole shows no 
external pore. Dogiel believes that its function is sensory and has 
named the vacuole, the statocyst, and the enclosed grains, the 

Food vacuoles are conspicuously present in the holozoic Protozoa 
which take in whole or parts of other organisms as food. The food 
vacuole is a space in the cytoplasm, containing the fluid medium 
which surrounds the protozoans and in which are suspended the 
food matter, such as various Protophyta, other Protozoa or small 
Metazoa. In the Sarcodina and the Mastigophora which do not 
possess a cytostome, the food vacuoles assume the shape of the food 
materials and, when these particles are large, it is difficult to make 
out the thin film of water which surrounds them. When minute food 


particles are taken through a cytostome, as is the case with the 
majority of euciliates, the food vacuoles are usually spherical and 
of approximately the same size within a single protozoan. In the 
saprozoic Protozoa, which absorb fluid substances through the body 
surface, food vacuoles containing solid food, of course, do not occur. 




Fig. 32. a, Trachelomonas hispida, X530 (Doflein); b, c, living and 
stained reproductive cells of Pleodorina illinoisensis, XlOOO (Merton); 
d-f, terminal cells of Hydrurus foetidus, showing division of chromato- 
phore and pyrenoid (Geitler); g-i, Chlamydomonas sp., showing the di- 
vision of pyrenoid (Geitler). 

Chromatophore and associated organellae 

In the Phytomastigina and certain other forms which are green- 
colored, one to many chromatophores (Fig. 32) containing chloro- 
phyll occur in the cytoplasm. The chromatophores vary in form 
among different species; namely, discoidal, ovoid, band-form, rod- 
like, cup-like, fusiform, network or irregularly diffused. The color 
of the chromatophore depends upon the amount and kinds of pig- 
ment which envelops the underlying chlorophyll substance. Thus the 
chromatophores of Chrysomonadina are brown or orange, as they 
contain one or more accessory pigments, including phycochrysin, 
and those of Cryptomonadina are of various types of brown with 


very diverse pigmentation. In Chloromonadina, the chromatophores 
are bright green, containing an excess of xanthophyll. In dinoflagel- 
lates, they are dark yellow or brown, because of the presence of 
pigments: carotin, phylloxanthin, and peridinin (Kylin, 1927), the 
last of which is said to give the brown coloration. A few species of 
Gymnodinium contain blue-green chromatophores for which phyco- 
cyanin is held to be responsible. The chromatophores of Phytomon- 
adina and Euglenoidina are free from any pigmentation, and there- 
fore green. Aside from various pigments associated with the chro- 
matophores, there are carotinoid pigments which occur often outside 
the chromatophores, and are collectively known as haematochrome. 
The haematochrome occurs in Haematococcus pluvialis, Euglena 
sanguinea, E. rubra, Chlamydomonas, etc. In Haematococcus, it in- 
creases in volume and in intensity when there is a deficiency in phos- 
phorus and especially in nitrogen; and when nitrogen and phos- 
phorus are present sufficiently in the culture medium, the haemato- 
chrome loses its color completely (Reichenow, 1909; Pringsheim, 
1914). Steinecke also noticed that the frequent yellow coloration of 
phytomonads in moorland pools is due to a development of carotin in 
the chromatophores as a result of deficiency in nitrogen. Johnson 
(1939) noted that the haematochrome granules of Euglena rubra be- 
come collected in the central portion instead of being scattered 
throughout the body when sunlight becomes weaker. Thus this Eu- 
glena appears green in a weak light and red in a strong light. The 
chromatophores undergo division at the time when the organism 
which contains them, divides, and therefore the number of chroma- 
tophores appears to remain about the same through different genera- 
tions (Fig. 32). 

In association with the chromatophores are found the pyrenoids 
(Fig. 32) which are usually embedded in them. The pyrenoid is a 
viscous structureless mass of protein (Czurda), and may or may not ' 
be covered by tightly fitting starch-envelope, composed of several 
pieces or grains which appear to grow by apposition of new material 
on the external surface. A pyrenoid divides when it reaches a certain 
size, and also at the time of the division of the organism in which it 
occurs. As to its function, it is generally agreed that the pyrenoid is 
concerned with the formation of the starch and allied anabolic prod- 
ucts of photosynthesis. Pyrenoid (Geitler, 1926). 

Chromatophore-bearing Protozoa usually possess also a stigma 
(Fig. 32) or eye-spot. The stigma may occur in exceptional cases 
in colorless forms, as in Khawkinea, Polytomella, etc. It is ordi- 
narily situated in the anterior region and appears as a reddish or 


brownish red dot or short rod, embedded in the cortical layer of the 
cytoplasm. The color of the stigma is due to the presence of droplets 
of haematochrome in a cytoplasmic network. The stigma is incapable 
of division and a new one is formed de novo at the time of cell divi- 
sion. In many species, the stigma possesses no accessory parts, but, 
according to Mast (1928), the pigment mass in Chlamydomonas, 
Pandorina, Eudorina, Euglena, Trachelomonas, etc., is in cup-form, 
the concavity being deeper in the colonial than in solitary forms. 
There is a colorless mass in the concavity, which appears to function 
as a lens. In certain dinoflagellates, there is an ocellus (Fig. 127, c, d, 
q, h) which is composed of amyloid lens and a dark pigment mass 
(melanosome) that is sometimes capable of amoeboid change of form. 
The stigma is, in general, regarded as an organella for the perception 
of light intensity. Mast (192G) considers that the stigma in the Vol- 
vocidae is an organella which determines the direction of the move- 


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Arch. Protist., 61:144. 
Richardson, K. C. and Horning, E. S.: (1931) Cytoplasmic struc- 
tures in binucleate opalinids with special reference to the Golgi 

apparatus. J. Morphol. Physiol., 52:27. 
Roskin, G.: (1923) La structure des mvonemes des infusoires. Bull. 

biol. France et Belg., 57:143. 
— (1925) Ueber die Axopodien der Heliozoa und die Greiften- 

takel der Ephelotidae. Arch. Protist,, 52:207. 

and Levinsohn, L. B.: (1929) Die Kontractilen und die 

Skelettelemente der Protozoen. I. Ibid., 66:355. 
Rumjantzew, A. and Wermel, E. : (1925) Untersuchungen ueber 

den Protoplasmabau von Actinosphaerium eichhorni. Ibid., 52: 

Saunders, J. T.: (1925) The trichocysts of Paramecium. Proc. 

Cambridge Philos. Soc, Biol. Sc, 1:249. 
Schroder, O.: (1906) Beitrage zur Kenntnis von Stentor coeruleus 

und St. roeselii. Arch. Protist,, 8:1. 
Schuberg, A.: (1888) Die Protozoen des Wiederkauermagens. I. 

Zool. Jahrb., Abt. Syst,, 3:365. 
Sharp, R. : (1914) Diplodinium ecaudatum with an account of its 

neuromotor apparatus. Univ. California Publ. Zool., 13:43. 


Strelkow, A.: (1929) Morphologische Studien ueber oligotriche In- 

fusorien aus dem Darme des Pferdes. I. Arch. Protist., 68:503. 
Taylor, C. V.: (1920) Demonstration of the function of the neuro- 
motor apparatus in Euplotes by the method of micro-dissection. 

Univ. California Publ. Zool., 19:403. 
(1941) Ciliate fibrillar systems. In: Calkins and Summers' 

Protozoa in biological research. 
ten Kate, C. G. B.: (1927) Ueber das Fibrillensvstem der Ciliaten. 

Arch. Protist., 57:362. 

(1928) II. Ibid., 62:328. 

Thon, K. : (1905) Ueber den feineren Ban von Didinium nasutum. 

Ibid., 5:282. 
Tobie, Eleanor J.: (1951) Loss of the kinetoplast in a strain of 

Trypanosoma equiperdum. Tr. Am. Micr. Soc, 70:251. 
Tonniges, C: (1914) Die Trichocysten von Frontonia leucas und 

ihr chromidialer Ursprung. Arch. Protist., 32:298. 
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notes on the neuromotor apparatus. Biol. Bull., 64:53. 
(1937) Studies on the ciliate Tillina canalifera n. sp. Tr. 

Am. Micr. Soc, 56:447. 

(1940) Cytoplasmic inclusions in the ciliate, Tillina canali- 

fera. Arch. Protist., 93:255. 

Verworn, M.: (1903) Allgemeine Physiologic 4th ed. Jena. 

Visscher, J. P.: (1926) Feeding reactions in the ciliate Dileptus 
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Vlk, W.: (1938) Ueber den Bau der Geissel. Arch. Protist., 90:-148. 

Weatherby, J. H.: (1941) The contractile vacuole. In: Calkins and 
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Weisz, P. B.: (1948) The role of carbohydrate reserves in the re- 
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(1949) A cytochemical and cytological study of differentia- 
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(1950) On the mitochondrial nature of the pigmented gran- 
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Wetzel, A.: (1925) Vergleichend cytologische Untersuchungen an 
Ciliaten. Arch. Protist., 51:209. 

Wilber, C. G. : (1942) The cytology of Pelomyxa carolinensis. Trans. 
Am. Micr. Soc, 61:227. 

(1945) Origin and function of the protoplasmic constituents 

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Wohlfarth-Bottermann, K-E. : (1950) Funktion und Struktur der 
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Woodruff, L. L. and Spencer, H.: (1922) Studies on Spathidium 
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Yocom, H. B. : (1918) The neuromotor apparatus of Euplotes patella. 
Univ. California Publ. Zool., 18:337. 

Chapter 4 

THE morphological consideration which has been given in the 
last chapter, is, though necessarily brief, indicative of the occur- 
rence of various and often complex organellae in Protozoa. The 
physiological activity of the whole protozoan is the sum-total of 
all the functions which are carried on by numerous minute parts or 
organellae of the cell body, unlike the condition found in a metazoan. 
Indeed, as Calkins (1933) stated, "physiological problems (of 
Protozoa) for the most part begin where similar problems of the 
Metazoa leave off, namely the ultimate processes of the single cell. 
Here the functional activities have to do with the action and inter- 
action of different substances which enter into the make-up of 
protoplasm and, for the most part, these are beyond our powers of 
analysis." A full discussion of various physiological problems per- 
taining to Protozoa is out of question in the present work and, there- 
fore, a general consideration on protozoan physiology will suffice 
for our purpose. 


Protozoa obtain nourishment in manifold ways. Information on 
the nutrition of the Protozoa is undergoing an accelerated progress 
through improvements in technique in experimental cultivation. In 
many Phytomastigina (Pringsheim, 1937a; Hall, 1939), afewciliates 
(Kidder and Dewey, 1951) and many blood-inhabiting flagellates 
(Lwoff, 1951) which have been cultivated in vitro free from other 
organisms, a much clearer information is becoming available. But 
for the majority of Protozoa a thorough comprehension of the nutri- 
tion is to be sought in future (Doyle, 1943; Lwoff, 1951; Most, 1951; 
Kidder, 1951). 

Holozoic (zootrophic, heterotrophic) nutrition. This is the method 
by which all higher animals obtain their nourishment; namely, the 
protozoan uses other animals or plants as sources of food. It involves 
the food-capture and ingestion, digestion and assimilation, and re- 
jection of indigestible portions. 

The methods of food-capture vary among different forms. In the 
Sarcodina, the food organisms are captured and taken into the body 
at any point. The methods however vary. According to Rhumbler's 
(1910) oft-quoted observations, four methods of food-ingestion oc- 
cur in amoebae (Fig. 33) ; namely, (1) by "import," in which the food 
is taken into the body upon contact, with very little movement on 



the part of the amoeba (a); (2) by "circumfluence,'' in which the 
cytoplasm flows around the food organism as soon as it comes in 
contact with it on all sides and engulfs it (6) ; (3) by "circumvalla- 
tion," in which the amoeba without contact with the food, forms 
pseudopodia which surround the food on all sides and ingest it (c) ; 

Fig. 33. Various ways by which amoebae capture food organisms, 
a, A moeba verrucosa feeding on Oscillatoria by 'import' (Rhumbler) ; b, A . 
proteus feeding on bacterial glea by 'circumfluence'; c, on Paramecium 
by 'circumvallation' (Kepner and Whitlock) ; d-h, A. verrucosa ingesting 
a food particle by 'invagination' (Gross-Allermann). 

(4) by "invagination," in which the amoeba touches and adheres to 
the food, and the ectoplasm in contact with it is invaginated into the 
endoplasm as a tube, the cytoplasmic membrane later disappears 
(d-h). In a species of Hartmannella, Ray (1951) reports an aggluti- 
nation of large numbers of motile bacteria over the body surface, 
which later form a large mass and are taken into a food cup. 

In certain testaceans, such as Gromia, several rhizopodia cooper- 
ate in engulfing the prey and, in Lieberkuhnia (Fig. 34), Verworn 
noted ciliates are captured by and digested in rhizopodia. Similar 



observation was made by Schaudinn in the heliozoan Camptonema in 
which several axopodia anastomose to capture a prey (Fig. 214, d). 
In the holozoic Mastigophora, such as Hypermastigina, which do 
not possess cytostome, the food-ingestion is by import or invagina- 
tion as noted in Trichonympha campanula (Cleveland, 1925a; Emik, 
1941) (Fig. 35, a) and Lophomonas blattarum (Kudo, 1926). 

The food particles become attached to the pseudopodium and are 
held there on account of the viscid nature of the pseudopodium. The 
sudden immobility of active organisms upon coming in contact with 
pseudopodia of certain forms, such as Actinophrys, Actinosphaer- 
ium, Gromia, Elphidium, etc., suggests, however, probable discharge 
of poisonous substances. In the Suctoria which lack a cytostome, the 
tentacles serve as food-capturing organellae. The suctorial tentacle 

Fig. 34. 

Rhizopodium of Lieberkiihnia, capturing and digesting 
Colpidium colpoda (Vervvorn). 

bears on its distal end a rounded knob which, when it comes in con- 
tact with an actively swimming ciliate, stops the latter immediately 
(Parapodophrya typha, Fig. 369, a). The prehensile tentacles of 
Ephelotidae are said to be similar in structure to the axopodia, in 
that each possesses a bundle of axial filaments around a cytoplasmic 
core (Roskin, 1925). These tentacles are capable of piercing through 
the body of a prey. In some suctorians, such as Choanophrya (Fig. 
374, a), the tubular tentacles are clearly observable, and both solid 
and liquid food materials are sucked in through the cavity. The 
rapidity with which tentacles of a suctorian stop a very actively 
swimming ciliate is attributed to a certain substance secreted by the 
tentacles, which paralyses the prey. 

In the cytostome-bearing Mastigophora, the lashing of flagella 
will aid in bringing about the food particles to the cytostome, where 



it is taken into the endoplasm. Chen (1950) observed Peranema feed- 
ing on immobile organisms. When the tip of the anterior flagellum 
comes in contact with an immobile Euglena, the whole flagellum 

Fig. 35. a, eight outline sketches of a Trichonympha campanula, in- 
gesting a large particle of food, XI 50 (Emik); b, four outline sketches of 
a Peranema trichophorum feeding on an immobile Euglena (Chen). 

beats actively and the body contracts, followed by elongation. The 
process is repeated several times until the body touches Euglena. 
Then the cytostome stretches open, the oral rods move up, protrude 
from the body and become attached to Euglena. Peranema advances 


toward the prey and the whole Euglena is engulfed in 2 to 15 min- 
utes (Fig. 35, b). 

In the ciliates, there are many types of cytostome and associated 
organelles, but the food-capturing seems to be in general of two 
kinds. When the cytostome is permanently open, the organism in- 
gests continuously food particles that are small enough to pass the 
cytostome and cytopharynx, as in the case of Paramecium. The 
other type is carried on by organisms bearing cytostome which is 
ordinarily closed such as seen in Coleps, Didinium, Perispira (Dewey 
and Kidder, 1940), but which expands to often an extraordinary size 
when the ingestion of prey takes place. Cannibalism in Protozoa 
(Dawson, 1919; Lapage, 1922; Gelei, 1925a; Tanabe and Komada, 
1932; Giese and Alden, 1938; Chen, 1950). 

The ingested food particles are usually surrounded by a film of 
fluid which envelops the organism and the whole is known as the 
food vacuole (p. 88). The quantity of fluid taken in with the food 
varies greatly and, generally speaking, it seems to be inversely pro- 
portional to the size, but proportional to the activity, of the food 
organisms. Food vacuoles composed entirely of surrounding liquid 
medium have occasionally been observed. Edwards (1925) noticed 
ingestion of fluid medium by an amoeba by forming food-cups under 
changed chemical composition. Brug (1928) reports seeing Ent- 
amoeba histolytica engulf liquid culture medium by formation of lip- 
like elevation of the ectoplasm and Kirby (1932) figures ingestion 
of the brine containing no visible organisms by the cytostome of 
Rhopalophrya salina (Fig. 36). Mast and Doyle (1934) state that if 
Amoeba proteus, A. dubia, A. dofleini, or A. radiosa is placed in an 
albumin solution, a hypertonic balanced salt solution, or a hyper- 
tonic solution of calcium gluconate it rapidly decreases in volume, 
and forms numerous tubes filled with fluid, which disintegrate sooner 
or later and release their fluid content in the cytoplasm. At times 50 
or more such tubes may be present, which indicates that the organism 
ingests considerable quantities of fluid in this way. The two authors 
consider that it is "a biological adaptation which serves to compen- 
sate for the rapid loss of water." 

The food vacuoles finally reach the endoplasm and in forms such 
as Amoebina the vacuoles are carried about by the moving endo- 
plasm. In the ciliates, the fluid endoplasm shows often a definite 
rotation movement. In Paramecium, the general direction is along 
the aboral side to the anterior region and down the other side, with 
a short cyclosis in the posterior half of the body. 

Some observers maintain that in ciliates there is a definite "diges- 



tive tubule" beginning with the cytostome and ending in the cyto- 
pyge, and the food vacuoles travel through it. Cosmovici (1931, 
1932) saw such a canal in soluble starch-fed Colpidium colpoda upon 
staining with iodine, but Hall and Alvey (1933) could not detect 
such a structure in the same organism. Kitching (1938b) observed 
no such tubule in the peritrichous ciliates he studied, and concluded 
that the food vacuoles are propelled over the determined part of the 
course by the contraction of surrounding cytoplasm. In Vorticella 
sp., food vacuoles are formed one by one at the end of cytopharynx, 
migrate through different parts of the cytoplasm without order and 
food material is digested (Fig. 37, a). Old food vacuoles are defecated 
through a small papilla on the lower wall of the cytopharynx and 
thence to the outside (Hall and Dunihue, 1931) (Fig. 37, b-d). 


n tr\ n n 

Fig. 36. Ingestion of brine by Rhopalophrya salina (Kirbj'). 

As stated above, in a number of species the food organisms are 
paralyzed or killed upon contact with pseudopodia, tentacles or ex- 
ploded trichocysts. In numerous other cases, the captured organism 
is taken into the food vacuole alive, as will easily be noted by ob- 
serving Chilomonas taken in by Amoeba proteus or actively moving 
bacteria ingested by Paramecium. But the prey ceases to move in a 
very short time. It is generally believed that some substances are se- 
creted into the food vacuole by the protoplasm of the organisms to 
stop the activity of the prey within the food vacuole. Engelmann 
(1878) demonstrated that the granules of blue litmus, when ingested 
by Paramecium or Amoeba, became red in a few minutes. Brandt 
(1881) examined the staining reactions of amoebae by means of 
haematoxylin, and found that the watery vacuoles contained an 
acid. Metschnikoff (1889) also showed that there appears an acid 
secretion around the ingested litmus grains in Mycetozoa. Green- 
wood and Saunders (1894) found in Carchesium that ingestion of 



food particles stimulated the cytoplasm to secrete a mineral acid. 
According to Nirenstein (1925), the food vacuole in Paramecium 
undergoes change in reaction which can be grouped in two periods. 
The first is acid reaction and the second alkaline reaction, in which 
albumin digestion takes place. On the other hand, Khainsky (1910) 
observed that the food vacuole of ciliates, such as Paramecium, is 

Fig. 37. Diagrams showing movements of food vacuoles in Vorticella 
sp. (Hall and Dunihue). a, diagram of the migration paths of six food 
vacuoles (vacuoles 1, 2, most recently formed; 3, 4, recently formed; 5, 6, 
formed some time before) ; b-d, stages in extrusion of a food vacuole (b, 
food vacuole entering gullet; c, a later stage; d, the food vacuole leaving 
cytostome, while another one is moving up toward the cytopyge). 

acid during the entire period of protein digestion, and becomes neu- 
tral to finally alkaline when the solution of the food substance is 
ended. Metalnikoff (1912) found that in the food vacuoles of Para- 
mecium, besides acid-alkaline reaction change, some vacuoles never 
show acid reaction and others occasionally show sustained acid reac- 
tion. Shapiro (1927) studied the reaction change of the food vacuoles 
in Paramecium caudatum by using phenol red, neutral red, Congo 
red, and litmus, and found that when the organism is kept in a 
medium with pH 7, its food vacuoles are first alkaline (pH 7.6), 
soon reach a maximum acidity (pH 4.0), while still in the posterior 


half of the body. Later, the vacuoles show a decreased acidity, finally 
reaching pH 7.0. In Vorticella sp. and Stylonychia pustulata, the 
range of pH observed in the food vacuoles was said to be 4.5- 
7.0 and 4.8-7.0 respectively. The food vacuoles of Actinosphaer- 
ium, according to Howland (1928), possess at the beginning pH 
6.0-7.0 for 5 to 10 minutes, but this soon changes to acid (pH 4.3) 
in which digestion appears to be carried on. In older food vacuoles 
which are of less acid (pH 5.4-5.6), the digestion appears to be at 
an end. In the species of Bresslaua, Claff, Dewey and Kidder (1941) 
noted that a Colpoda taken into the food vacuole is instantly killed 
with a sudden release of an acid which shows pH 3.0-4.2. During 
digestion the protoplasm of the prey becomes alkaline and the un- 
digested residue becomes acid before extrusion. 

Mast's observations (1942) on the food vacuoles in Amoeba pro- 
teus and A. dubia containing Chilomonas or Colpidium, indicate: 

(1) the fluid in the vacuoles becomes first acid and then alkaline; 

(2) the increase in the acidity of the fluid in the vacuole is not due to 
cytoplasmic secretion, but is probably due to respiration in the in- 
gested organisms, chemical changes associated with their death, 
etc.; and (3) the death of the organisms taken in the food vacuoles is 
probably caused by the decrease in oxygen in the vacuoles, owing to 
the respiration of the organisms in them. De La Arena (1941, 1942) 
found the maximum acidity of the fluid of food vacuoles in Pelomyxa 
carolinensis containing Colpidium striatum was pH 5.8 and was not 
fatal for the ciliate, but considered the possibility of the existence in 
the food vacuole of "some lethal agent" which kills the prey. 

Just exactly what processes take place in the food vacuole have 
been observed only in a few cases. Nirenstein (1925) noticed the ap- 
pearance of numerous neutral red-stainable granules around the food 
vacuole which pass into the interior of the vacuole, and regarded 
them as carriers of a tryptic ferment, while Roskin and Levinsohn 
(1926) demonstrated the oxidase reaction in these granules. Hopkins 
and Warner (1946) believe that the digestion of food in Entamoeba 
histolytica is brought about by enzymes carried to the food vacuoles 
by "digestive spherules" which arise at the periphery of the nucleus, 
apparently due to the action of the substances diffusing from the nu- 
cleus into the cytoplasm. 

As to the localization or distribution of enzymes within protozoan 
body, definite information is not yet available. In centrifuged 
Amoeba proteus, Holter and Kopac (1937) found the peptidase ac- 
tivity independent of all cytoplasmic inclusions that were stratified 
by centrifugal forces. Holter and L0vtrup (1949) found peptidase in 


centrifuged Pelomyxa carolinensis comparatively evenly distributed 
after centrifugation, possibly with a tendency to be concentrated in 
the lighter half, while proteinase was largely localized in the heavier 
half in which cytoplasmic granules were accumulated, and concluded 
that these two enzymes are bound, at least in part, to different cyto- 
plasmic components. A number of enzymes have been reported to 
occur in Protozoa, some of which are listed in Table 3. 

These findings suffice to indicate that the digestion in Protozoa 
is carried on also by enzymes and its course appears to vary among 
different Protozoa. The albuminous substances are digested and de- 
composed into simpler compounds by enzymes and absorbed by the 
surrounding cytoplasm. The power to digest starch into soluble 
sugars is widely found among various Protozoa. It has been re- 
ported in Mycetozoa, Foraminifera, Pelomyxa, Amoeba, Enta- 
moeba, Ophryoscolecidae and other ciliates by several investigators. 

The members of Vampyrella (p. 420) are known to dissolve the 
cellulose wall of algae, especially Spirogyra in order to feed on their 
contents. Pelomyxa (Stole), Foraminifera (Schaudinn), Amoeba 
(Rhumbler), Hypermastigina, Polymastigina (Cleveland), etc., have 
also been known for possessing the power of cellulose digestion. 
Many of the Hypermastigina and Polymastigina which lead symbi- 
otic life in the intestine of the termite and of the wood roach, as dem- 
onstrated by Cleveland and his co-workers, digest by enzymes the 
cellulose which the host insect ingests. The assimilation products 
produced by an enormous number of these flagellates are seemingly 
sufficient to support the protozoans as well as the host. The cili- 
ate commensals inhabiting the stomach of ruminants also appar- 
ently digest the cellulose, since the faecal matter as a rule does not 
contain this substance (Becker et al., 1930; Weineck, 1934). 

Dawson and Belkin (1928) injected oils into Amoeba dubia and 
found 1.4 to 8.3 per cent digested. Mast (1938) reported that the 
neutral fat globules of Colpidium are digested by Amoeba proteus 
and transformed into fatty acid and glycerine which unite and form 
neutral fat. Chen (1950) found that when Peranema trichophorum 
was fed on almond oil (stained dark blue with Sudan black), Sudan 
III-stainable droplets gradually increased in number in five to 10 
hours, while ingested oil-droplets decreased in size, and considered 
that the droplets were "fat-substances" resynthesized from prod- 
ucts of digestion of almond oil by this flagellate. The digestion of 
rice starch is followed by the appearance of increasing number of 
ovoid paramylon granules, and the digestion of casein results in the 
formation of oil droplets and paramylon bodies. 



Table 3. — Enzymes in Protozoa 




Amoeba proteus 


Holter and Kopac (1 937) ; 
Holter and Doyle (1938); 
Andresen and Holter (1949); 
Holter and Ljtfvtrup (1949) 


Andresen and Holter (1949); 
Holter and Ljrfvtrup (1949) 


Holter and Doyle (1938a) 

A. dubia 

Lipolytic substance 

Dawson and Belkin (1928) 

Pelornyxa palustris 

Diastatic enzyme 

Hartog and Dixon (1893) ; 
Stole (1900) 

Pepsin-like enzyme 

Hartog and Dixon (1893) 


Andresen and Holter (1949) 



P. carolinensis 





Succinic dehydro- 

Andresen, Engel and Holter 




Wilber (1946) 

Soil amoeba 

" Amoebo-diastase, " 
a trypsin-like en- 

Mouton (1902) 

Aethalium seftticum 

Pepsin-like enzyme 

Krukenberg (1886) 

Eitglena gracilis 

Proteolytic enzyme 

Jahn (1931) 

Xylophagous Poly- 


Trager (1932) 

and Hyper-mas- 


Cleveland et ah (1934) 


Didinium nasutum 


Doyle and Patterson (1942) 

Tetrahymena pirifor- 

Proteolytic enzyme 

Lwoff (1932); Lawrie (1937) 



Kidder and Dewey (1951) 


Seaman and Houlihan (1951) 

Colpidium striatum 

Proteolytic enzyme 

Elliott (1933) 

Paramecium cau- 


Holter and Doyle (1938) 




P. multimicronuclea- 

Frontonia sp. 


Doyle and Patterson (1942) 


Holter and Doyle (1938) 



Balantidium coli 


Glaessner (1908) 

In certain Sarcodina such as Amoeba and Pelornyxa, refringent 
bodies occur conspicuously in the cytoplasm. They were first noticed 
in Pelornyxa palustris by Green" (1874) who called them "Glanz- 
korper." Stole (1900) and Leiner (1924) considered them as glycogen 
enclosed within a membrane and associated intimately with the 


carbohydrate metabolism of the organism, since their number was 
proportionate to the amount of food obtained by the organism. 
Veley (1905) on the other hand found them albuminoid in nature. 
Studies of the refringent bodies in Amoeba proteus led Mast and 
Doyle (1935, 1935a) to conclude that the outer layer is composed of 
a protein stroma impregnated with lipid containing fatty acid, which 
gives positive reaction for Golgi substance; the envelope is made up 
of a carbohydrate which is neither starch nor glycogen; and the re- 
fringent bodies function as reserve food, since they disintegrate dur- 
ing starvation. The same function was assigned to those occurring in 
Pelomyxa carolinensis by Wilber (1945, 1945a), but Andresen and 
Holter (1945) do not agree with this view, as they observed the 
number of the refringent bodies ("heavy spherical bodies") remains 
the same in starvation. Thus a full comprehension of the nature and 
function of the refringent body must depend on future observations. 

The indigestible residue of the food is extruded from the body. 
The extrusion may take place at an}' point on the surface in many 
Sarcodina by a reverse process of the ingestion of food. But in pelli- 
cle-bearing forms, the defecation takes place either through the 
cytopyge located in the posterior region of the body or through an 
aperture to the vestibule (Fig. 37, b-d). Permanent cytopyge is lack- 
ing in some forms. In Fabrea salina, Kirby (1934) noticed that a large 
opening is formed at the posterior end, the contents of food vacuoles 
are discharged, and the opening closes over. At first the margin of 
the body is left uneven, but soon the evenly rounded outline is re- 
stored. The same seems to be the case with Spirostomum (Fig. 38), 
Blepharisma, etc. Cytopyge (Klein, 1939). 

Holophytic (autotrophic, prototrophic) nutrition. This is the type 
of nutrition in which the Protozoa are able to decompose carbon 
dioxide by means of chlorophyll contained in chromatophores (p. 89) 
in the presence of the sunlight, liberating the oxygen and combining 
the carbon with other elements derived from water and inorganic 
salts (photosynthesis). Aside from the Phytomastigina, chromato- 
phores were definitely observed in a ciliate Cyclotrichium meunieri 
(Figs. 300, o; 301) (Powers, 1932; Bary and Stuckey, 1950). In a 
number of other cases, the organism itself is without chromatophores, 
but is apparently not holozoic, because of the presence of chloro- 
phyll-bearing organisms within it. For example, in the testacean 
Paulinella (Fig. 206, c) in which occur no food vacuoles, chromato- 
phores of peculiar shape are always present. The latter appear to be 
a species of alga which holds a symbiotic relationship with the 
testacean, and perhaps acts for the sarcodinan as the chromatophores 



of the Phytomastigina. A similar relationship seems to exist between 
Paramecium bursaria, Stentor pohjmorphus, etc. and zoochlorellae; 
Paraeuplotes tortugensis and a zooxanthella and others (p. 29). 
Pringsheim (1928) showed that organic matters from zoochlorellae 
are passed on to their host, Paramecium bursaria, to be used as food. 
Through studies of relationships between zooxanthellae and in- 
vertebrates, Yonge observed that the zooxanthellae utilize carbon 
dioxide, nitrogen and phosphorus which are the catabolic products 
of the host and supply in return oxygen, fats and carbohydrates to 
the host. Photosynthesis in Phytomastigina (Hutner and Provasoli, 

Saprozoic (saprophytic) nutrition. In this nutrition, the Protozoa 
obtain nourishment by diffusion through the body surface. This is 
accomplished without any special organellae. Perhaps the only in- 

Fig. 38. Outline sketches showing the defecation process in 
Spirostomum ambiguum (Blattner). 

stance in which the saprozoic nutrition is accomplished through a 
special organella is the pusules (Figs. 127, 129) in marine dinoflagel- 
lates which, according to Kofoid and Swezy (1921), appear to con- 
tain decomposed organic matter and aid the organisms in carrying 
on this process. 

The dissolved food matters are simpler compounds which originate 
in animal or vegetable matter due to the decomposing activities of 
bacterial organisms. Numerous free-living flagellates nourish them- 
selves with this method. Recently a number of investigators found 
that saprozoic Protozoa could be cultivated in bacteria-free media 
of known compositions. For example, Pringsheim (1937) observed in 
Polytoma uvella (Fig. 113, h) that sodium acetate is needed from 
which the starch among others is produced and carbohydrates have 
no direct bearing upon the nutrition, but fatty acids derived from 
them participate in the metabolism. 

The Protozoa which live within the body of another organism are 


able to nourish themselves by absorbing the digested or decomposed 
substances of the host and could be considered assaprozoic, though 
the term parasitic has sometimes been used. Coelozoic Protozoa be- 
long to this group, as for example, Protociliata, astomatous ciliates, 
Trypan osomatidae, etc. In the case of cytozoic or certain histozoic 
forms, such as Cnidosporidia, the host cytoplasm is apparently 
liquefied or hydrolyzed by enzymes before being absorbed by them. 
The parasitic Protozoa, which actually feed on host tissue cells, such 
as Entamoeba histolytica, Balantidium coli, etc., or endo commensals, 
{Endamoeba blattae, Entamoeba coli, etc.) employ, of course, the holo- 
zoic nutrition. 

Many Protozoa nourish themselves by more than one method at 
the same or different times, subject to a change in external condi- 
tions. This is sometimes referred to as mixotrophic nutrition (Pfeif- 
fer). For example, Euglena gracilis, according to Zumstein (1900), 
Lwoff (1932) and Pringsheim and Hovasse (1948), loses its green 
coloration in the darkness or even in the light when the culture 
medium is very abundant in decomposed organic substances, which 
may indicate that this organism is capable of carrying on both holo- 
phytic and saprozoic nutrition. 

With the introduction of bacteria-free culture technique in recent 
years, it has now become well established that a protozoan species 
exhibits conspicuous differences in form, size and structure, which 
are exclusively due to differences in the kind and amount of food 
material. For example, Kidder, Lilly and Claff (1940) noted in 
Tetrahymena vorax (Fig. 39), bacteria-feeders are tailed (50-75^ 
long), saprozoic forms are fusiform to ovoid (30-70/x long), forms 
feeding on sterile dead ciliates are fusiform (60-80^ long), and carni- 
vores and cannibals are irregularly ovoid (100-250^ long), in the latter 
form of which a large "preparatory vacuole" becomes developed. 
In Chilomonas Paramecium, Mast (1939) observed the individuals 
grown in sterile glucose-peptone solution were much smaller than 
those cultured in acetate-ammonium solution and moreover the 
former contained many small starch grains, but no fat, while the 
latter showed many larger starch grains and a little fat. Amoeba 
proteus when fed exclusively on Colpidium, became very large and 
extremely "fat" and sluggish, growing and multiplying slowly, but 
indefinitely; when fed on Chilomonas only, they grew and multi- 
plied for several days, then decreased in number and soon died, but 
lived longer on Chilomonas cultured in the glucose-peptone. It is 
well known that Protozoa as any other organism, show atypical 
or abnormal morphological and physiological peculiarities. In the 



case of carnivorous forms, the condition of food organisms may pro- 
duce abnormalities in them, as was shown by Beers (1933) in Didi- 
nium fed on starved paramecia (Fig. 40). 

Some thirty years ago, Robertson (1921-1927) reported that when 
two ciliates, Enchelys and Colpoda, are placed in a small amount of 
fresh culture medium, the rate of reproduction following a "lag pe- 

Fig. 39. Form and size variation in Tetrahymena vorax, due to differ- 
ences in kind and amount of food material, as seen in life, X400 (Kidder, 
Lilly and Claff). a, bacteria-feeder; b, c, saprozoic forms; d, individual 
which has fed on killed Colpidium campylum; e, starved individual from 
a killed-Colpidium culture; f-i, progressive form and size changes of 
saprozoic form in the presence of living Colpidium; j, a young carnivore 
which has been removed to a culture with living yeast. 



riod" is more than twice (up to ten times) that of a single animal in 
the same amount of the medium. He assumed that this acceleration 
was due to a certain agent or substance produced within the animal, 

Fig. 40. Didinium nasutum, X265 (Beers), a, normal fully grown ani- 
mal; b-e, abnormal organisms which were fed on starved Paramecium. 

which diffused into the culture medium. When more than one animal 
is confined in a limited amount of culture fluid, this substance is 
present in a higher concentration than with one animal, and an in- 
creased rate of division is the result. Robertson called this "allelo- 
catalytic result," and the phenomenon, "allelocatalysis." 


Soon a large number of observers came forward with varying re- 
sults — some confirmatory, others contradictory. The vast majority 
of these observations including Robertson's own, were carried on 
ciliates which were grown in association with various bacteria, and 
naturally, the results lacked agreement. For a review of these ob- 
servations too numerous to mention here, the reader is referred to 
Allee (1931, 1934), Mast and Pace (1938) and Richards (1941). 
When bacteria-free cultivation became possible for some Protozoa, 
it was hoped that this problem might be solved under controlled 
conditions. How r ever, the results still lack agreement. For example, 
Phelps (1935) reported that in Tetrahymena (Glaucoma), the 
growth rate and the maximum yield were the same between tw r o 
cultures: one started with 0.014 organism and the other, with 1600 
organisms per ml. Thus there was no allelocatalysis. On the other 
hand, Mast and Pace (1938) noted a significant acceleration of the 
growth rate in Chilomonas when up to 50 organisms were inoculated 
into 0.4 cc. of culture fluid as compared to the growth rate in cultures 
with one or more Chilomonas inocula, and furthermore, a single 
Chilomonas showed an increased rate of reproduction as the volume 
of the culture fluid was reduced. 

Various aspects of metabolic processes in Protozoa such as inor- 
ganic requirements, carbon and nitrogen metabolism, growth fac- 
tors, vitamins, etc., have recently been studied by a number of in- 
vestigators. For information, the reader is referred to Hall (1941) 
and Lwoff (1951). 

Reserve food matter 

The anabolic activities of Protozoa result in the growth and in- 
crease in the volume of the organism, and also in the formation and 
storage of reserve food-substances which are deposited in the cy- 
toplasm to be utilized later for growth or reproduction. The re- 
serve food stuff is ordinarily glycogen or glycogenous substances, 
which seem to be present widely. Thus, in saprozoic Gregarinida, 
there occur in the cytoplasm numerous refractile bodies which stain 
brown to brownish-violet in Lugol's solution; are insoluble in cold 
water, alcohol, and ether; become swollen and later dissolved in boil- 
ing water; and are reduced to a sugar by boiling in dilute sulphuric 
acid. This substance which composes the refractile bodies is called 
paraglycogen (Biitschli) or zooamylon. Gohre (1943) considers it a 
stabilized polymerization product of glycogen. 

Rumjantzew and Wermel (1925) demonstrated glycogen in Ac- 
tinosphaerium. In the cysts of Iodamoeba, glycogen body is con- 



spicuously present and is looked upon as a characteristic feature of 
the organism. The iodinophile vacuole of the spores of Myxobolidae 
is a well-defined vacuole containing glycogenous substance and is 
also considered as possessing a taxonomic value. In many ciliates, 
both free-living (Paramecium, Glaucoma, Vorticella, Stentor, etc.) 
and parasitic (Ophryoscolecidae, Nyctotherus, Balantidium (Faure- 
Fremiet and Thaureaux, 1944)), glycogenous bodies are always 
present. According to MacLennan (1936), the development of the 
paraglycogen in Ichthyophthirius is associated with the chondrio- 
somes. In Eimeria tenella, glycogenous substance does apparently 
not occur in the schizonts, merozoites, or microgametocytes ; but 
becomes apparent first in the macrogametocyte, and increases in 
amount with its development, a small amount being demonstrable 
in the sporozoites (Edgar et al., 1944). 


Fig. 41. a-d, two types of paramylon present in Euglena gracilis 
(Btitschli); e-h, paramylon of E '. sanguinea, X1100 (Heidt). (e, natural 
appearance; f, g, dried forms; h, strongly pressed body.) 

The anabolic products of the holophytic nutrition are starch, 
paramylon, oil and fats. The paramylon bodies are of various forms 
among different species, but appear to maintain a certain character- 
istic form within a species and can be used to a certain extent in 
taxonomic consideration. According to Heidt (1937), the paramylon 
of Euglena sanguinea (Fig. 41) is spirally coiled which confirms 
Butschli's observation. The paramylon appears to be a polysac- 
charide which is insoluble in boiling water, but dissolves in concen- 
trated sulphuric acid, potassium hydroxide, and slowly in formalde- 
hyde. It does not stain with either iodine or chlor-zinc-iodide and 
when treated with a dilute potassium hydroxide, the paramylon 
bodies become enlarged and frequently exhibit a concentric stratifi- 

In the Chrysomonadina, the reserve food material is in the form 
of refractile spheroid bodies which are known as leucosin, probably 
a carbohydrate which when boiled in water stains with iodine. Oil 



droplets occur in various Protozoa and when there is a large number 
of oil-producing forms in a body of water, the water may develop 
various odors as indicated in Table 4. 

Table 4. — Protozoa and odors of water 


Odor produced by them 


candied violets 


aromatic, violets, fishy 


ripe cucumber, muskmelon, bitter and 

spicy taste 


fishy, cod-liver oil-like 


fishy, like rockweed 


fishy, unpleasant or aromatic 


faintly fishy 


faintly fishy 




vile stench 




fishy, like clam-shells 


Irish moss, salt marsh, fishy (Whipple, 



ripe cucumber (Schaeffer, 1937) 

Fats occur widely in Protozoa. They appear usually as small re- 
fractile globules. Zingher (1934) found that in the Sarcodina and 
Ciliata he studied, each species showed morphological characteristics 
of the fatty substance it contained. Fat globules occur abundantly 
in Amoeba and Pelomyxa which are easily seen by staining with 
Sudan III. In Tillina canalifera, fat droplets, 1-2/x in diameter, are 
present especially in the region to the right of the cytopharynx 
(Turner, 1940). According to Panzer (1913), the fat content of 
Eimeria gadi was 3.55 per cent and Pratje (1921) reports that 12 per 
cent of the dry matter of Noctiluca scintillans appeared to be the 
fatty substance present in the form of granules and is said to give 
luminescence upon mechanical or chemical stimulation. But the 
chemical nature of these "photogenic" granules is still unknown at 
present (Harvey, 1952). A number of other dinoflagellates, such as 
Peridinium, Ceratium, Gonyaulax, Gymnodinium, etc., also emit 
luminescence. In other forms the fat may be hydrostatic in function, 
as is the case with a number of pelagic Radiolaria, many of which 
are also luminous. Luminescence in Protozoa (Harvey, 1952). 

Another reserve food-stuff which occurs widely in Protozoa, ex- 
cepting Ciliophora, is the so-called volutin or metachromatic gran- 
ule. It is apparently equally widely present in Protophyta. In fact 
it was first discovered in the protophytan Spirillum volutans. Meyer 


coined the name and held it to be made up of a nucleic acid. It stains 
deeply with nuclear dyes. Reichenow (1909) demonstrated that if 
Haematococcus pluvialis (Fig. 42) is cultivated in a phosphorus-free 
medium, the volutin is quickly used up and does not reappear. If 
however, the organisms are cultivated in a medium rich in phos- 
phorus, the volutin increases greatly in volume and, as the culture 
becomes old, it gradually breaks down. In Polytomella agilis (Fig. 
114, c, d), Doflein (1918) showed that an addition of sodium phos- 
phate resulted in an increase of volutin. Reichenow, Schumacher^ 

Fig. 42. Haematococcus pluvialis, showing the development of volutin 
in the medium rich in phosphorus and its disintegration in an exhausted 
medium, X570 (Reichenow). a, second day; b, third day; c, fourth day; 
d, e, sixth day; f, eighth day. 

and others, hold that the volutin appears to be a free nucleic acid, 
and is a special reserve food material for the nuclear substance. Sas- 
suchin (1935) studied the volutin in Spirillum volutans and Sarcina 
flava and found that the volutin appears during the period of strong 
growth, nourishment and multiplication, disappears in unfavorable 
condition of nourishment and gives a series of characteristic carbo- 
hydrate reactions. Sassuchin considers that the volutin is not related 
to the nucleus, but is a reserve food material of the cell, and is 
composed of glycoprotein. Volutin (Jirovec, 1926). 

Starvation. As in all living things, when deprived of food, Protozoa 
perish sooner or later. The changes noticeable under the microscope 
are: gradual loss of cytoplasmic movement, increasing number of 
vacuoles and their coalescence, and finally the disintegration of the 
body. In starved Pelomyxa carolinensis, Andresen and Holter (1945) 
noticed the following changes: the animals disintegrate in 10-25 
days at 22°C. ; body volume decreases particularly during the early 
days of starvation and is about 20-30 per cent of the initial volume 
at the time of death; food vacuoles are extruded from the body in 24 
to 48 hours; the cytoplasm becomes less viscous and many fluid 
vacuoles make their appearance; crystals and refringent bodies en- 
closed within vacuoles, form large groups as the vacuoles coalesce, 
some of which are extruded from the body; crystals and refringent 
bodies remain approximately constant during starvation and there 


is no indication that they are utilized as food reserves. The ratio of 
reduced weight and volume and the specific gravity remain reason- 
ably constant during starvation (Zeuthen, 1948). Andresen (1945) 
found starved Amoeba proteus to show a similar change on the whole, 
except that the number of chondriosomes decreased and in some 
cases dissolution of crystals occurred just before disintegration. 


In order to carry on various vital activities, the Protozoa, like 
all other organisms, must transform the potential energy stored in 
highly complex chemical compounds present in the cytoplasm, into 
various forms of active energy by oxidation. The oxygen involved 
in this process appears to be brought into contact with the sub- 
stances in two ways in Protozoa. The great majority of free-living, 
and certain parasitic forms absorb free molecular oxygen from 
the surrounding media. The absorption of oxygen appears to be 
carried on by the permeable body surface, since there is no special 
organella for this purpose. The polysaprobic Protozoa are known 
to live in water containing no free oxygen. For example, Noland 
(1927) observed Metopus es in a pool, 6 feet in diameter and 18 inches 
deep, filled with dead leaves which gave a strong odor of hydrogen 
sulphide. The water in it showed pH 7.2 at 14°C, and contained no 
dissolved oxygen, 14.9 c.c. per liter of free carbon dioxide, and 78.7 
c.c. per liter of fixed carbon dioxide. The parasitic Protozoa of 
metazoan digestive systems live also in a medium containing no 
molecular oxygen. All these forms appear to possess capacity of 
splitting complex oxygen-bearing substances present in the body to 
produce necessary oxygen. 

Several investigators studied the influence of abundance or lack 
of oxygen upon different Protozoa. For example, Putter (1905) dem- 
onstrated that several ciliates reacted differently when subjected to 
anaerobic condition, some perishing rapidly, others living for a con- 
siderable length of time. Death is said by Lohner to be brought 
about by a volume-increase due to accumulation of the waste prod- 
ucts. When first starved for a few days and then placed in anaerobic 
environment, Paramecium and Colpidium died much more rapidly 
than unstarved individuals. Putter, therefore, supposed that the dif- 
ference in longevity of aerobic Protozoa in anaerobic conditions was 
correlated with that of the amount of reserve food material such as 
protein, glycogen and paraglycogen present in the body. Putter fur- 
ther noticed that Paramecium is less affected by anaerobic condition 
than Spirostomum in a small amount of water, and maintained that 


the smaller the size of body and the more elaborate the contractile 
vacuole system, the organisms suffer the less the lack of oxygen in 
the water, since the removal of catabolic products depends upon these 

The variety of habitats and results of artificial cultivations of 
various Protozoa indicate clearly that the oxygen requirements vary 
a great deal among different forms. Attempts were made in recent 
years to determine the oxygen requirement of Protozoa. The results 
of the observations are not always convincing. The oxygen consump- 
tion of Paramecium is said, according to Lund (1918) and Amberson 
(1928), to be fairly constant over a wide range of oxygen concentra- 
tion. Specht (1934) found the measurements of the oxygen con- 
sumption and carbon dioxide production in Spirostomum ambiguum 
vary because of the presence of a base produced by the organism. 
Soule (1925) observed in the cultural tubes of Trypanosoma lewisi 
and Leishmania tropica, the oxygen contained in about 100 c.c. of 
air of the test tube is used up in about 12 and 6 days respectively. 
A single Paramedian caudatum is said to consume in one hour at 
21°C. from 0.0052 c.c. (Kalmus) to 0.00049 c.c. (Howland and Bern- 
stein) of oxygen. The oxygen consumption of this ciliate in heavy 
suspensions (3X10 3 to 301 X10 3 in 3 c.c.) and associated bacteria, 
ranged, according to Gremsbergen and Reynaerts-De Pont (1952), 
from 1000 to 4000 nM 3 per hour per million individuals at 23.5°C. 
The two observers considered that P. caudatum possesses a typical 
cytochrome-oxidase system. Amoeba proteus, according to Hulpieu 
(1930), succumbs slowly when the amount of oxygen in water is less 
than 0.005 per cent and also in excess, which latter confirms Putter's 
observation on Spirostomum. According to Clark (1942), a normal 
Amoeba proteus consumes 1.4 X10~ 3 mm 3 of oxygen per hour, while 
an enucleated amoeba only 0.2X10 -3 mm 3 . He suggests that "the 
oxygen-carriers concerned with 70 per cent of the normal respiration 
of an amoeba are related in some way to the presence of the nu- 
cleus." In Pelomyxa caroUnensis, the rate of oxygen consumption at 
25°C. was found by Pace and Belda (1944) to be 0.244+0.028 mm 3 
per hour per mm 3 cell substance and does not differ greatly from 
that of Amoeba proteus and Actinosphaervum eichhorni. The tem- 
perature coefficient for the rate of respiration is nearly the same as 
that in Paramecium, varying from 1.7 at 15-25°C. to 2.1 at 25-35°C. 
Pace and Kimura (1946) further note in Pelomyxa caroUnensis that 
carbohydrate metabolism is greater at higher than at lower tem- 
perature and that a cytochrome-cytochrome oxidase system is the 
mechanism chiefly involved in oxidation of carbohydrate. 


The Hypermastigina of termites are killed, according to Cleve- 
land (1925), when the host animals are kept in an excess of oxygen. 
Jahn found that Chilomonas paramedian in bacteria-free cultures in 
heavily buffered peptone-phosphate media at pH 6.0, required for 
rapid growth carbon dioxide which apparently brings about a favor- 
able intracellular hydrogen-ion concentration. Respiratory metabo- 
lism (Meldrum, 1934; Jahn, 1941). 

Excretion and secretion 

The catabolic waste material composed of water, carbon dioxide, 
and nitrogenous compounds, all of which are soluble, pass out of the 
body by diffusion through the surface or by means of the contractile 
vacuole (p. 83). The protoplasm of the Protozoa is generally con- 
sidered to possess a molecular make-up which appears to be similar 
among those living in various habitats. In the freshwater Protozoa 
the body of which is hypertonic to surrounding water, the water 
diffuses through the body surface and so increases the water content 
of the body protoplasm as to interfere with its normal function. The 
contractile vacuole, which is invariably present in all freshwater 
forms, is the means of getting rid of this excess water from the body. 
On the other hand, marine or parasitic Protozoa live in nearly iso- 
tonic media and there is no excess of water entering the body, hence 
the contractile vacuoles are not found in them. Just exactly why 
nearly all euciliates and suctorians possess the contractile vacuole 
regardless of habitat, has not fully been explained. It is assumed that 
the pellicle of the ciliate is impermeable to salts and slowly permeable 
to water (Kitching, 1936) or impermeable to water, salts and prob- 
ably gases (Frisch, 1937). If this is the case with all ciliates, it is not 
difficult to understand the universal occurrence of the contractile 
vacuole in the ciliates and suctorians. 

That the elimination of excess amount of water from the body 
is one of the functions of the contractile vacuole appears to be be- 
yond doubt judging from the observations of Zuelzer (1907), Finley 
(1930) and others, on Amoeba verrucosa which lost gradually its con- 
tractile vacuole as sodium chloride was added to the water, losing 
the organella completely in the seawater concentration and of Yo- 
com (1934) on Paramecium caudatum and Euplotes patella, the con- 
tractile vacuoles of which nearly ceased functioning when the ani- 
mals were placed in 10 per cent sea water. Furthermore, marine 
amoebae develop contractile vacuoles de novo when they are trans- 
planted to fresh water as in the case of Vahlkampfia calkinsi (Hogue, 
1923) and Amoeba biddulphiae (Zuelzer, 1927). Herfs (1922) studied 


the pulsation of the contractile vacuoles of Paramecium caudatum in 
fresh water as well as in salt water and obtained the following meas- 

Per cent NaCl in water 





Contraction period in second 






Excretion per hour in body 







The number of the contractile vacuoles present in a species is con- 
stant under normal conditions. The contraction period varies from a 
few seconds to several minutes in freshwater inhabitants, and is, as 
a rule, considerably longer in marine Protozoa. Kitching (1938a) 
estimated that a quantity of water equivalent to the body volume is 
eliminated by freshwater Protozoa in four to 45 minutes and by 
marine forms in about three to four hours. The size of contractile 
vacuole in diastole may vary. Botsford (1926) reported that the con- 
tractile vacuole in Amoeba proteus varied considerably within a short 
period of time in size and rate of contraction under seemingly identi- 
cal conditions. The rate of contraction is subject to change with the 
temperature, physiological state of the organism, amount of food 
substances, etc. For example, Rossbach noted in the three ciliates 
listed below, the contraction was accelerated first rapidly and then 
more slowly with rise of the temperature: 

Time in seconds between two systoles at 
different temperature (C.) 

5° 10° 15° 20° 25° 30° 
Euplotes char on 61 48 31 28 22 23 

Stylonychia pustulata 18 14 10-11 6-8 5-6 4 

Chilodonella cucidlulus 9 7 5 4 4 — 

How much water enters through the body surface of Protozoa is 
not known, but it appears to be the major portion that is excreted 
through contractile vacuoles. Water also enters the protozoan body 
in food vacuoles. In Vampyrella lateritia which feeds on the cell con- 
tents of Spirogyra in a single feeding, many contractile vacuoles ap- 
pear within the cytoplasm and evacuate the Avater that has come in 
with the food (Lloyd, 1926) and the members of Ophryoscolecidae 
show an increased number and activity of contractile vacuoles while 
feeding (MacLennan, 1933). The amount of water contained in food 
vacuoles seems, however, to be far smaller than the amount evacu- 
ated by contractile vacuoles (Gelei, 1925; Eisenberg, 1925). Other 
evidences such as the contractile vacuole continues to pulsate when 
cytosome-bearing Protozoa are not feeding and its occurrence in 
automatons ciliates, would indicate also that the water entering 


through this avenue is not of a large quantity. How much water is 
produced during the metabolic activity of the organisms is un- 
known, but it is considered to be a very small amount (Kitching, 
1938). The mechanism by which the difference in osmotic pressure 
can be maintained at the body surface is unknown. It may be, as 
suggested by Kitching (1934), that the contractile vacuole extrudes 
water but retains the solutes or some osmotically active substances 
must be continuously produced within the body. 

Attempts to detect catabolic products in the contractile vacuole, 
in the body protoplasm or in the culture fluid, were unsuccessful, be- 
cause of technical difficulties. Weatherby (1927) detected in the 

Fig. 43. Examples of crystals present in Protozoa, a-e, in Paramecium 
caudatum (Schewiakoff), (a-d, X1000, e, X2600); f, in Amoeba protetis; 
g, in A. discoides; h-1, in A. dubia (Schaeffer). 

spring water in which he kept a number of thoroughly washed Para- 
mecium, urea and ammonia after 30-36 hours and supposed that 
the urea excreted by the organisms gave rise to ammonia. He found 
also urea in similar experiments with Spirostomum and Didinium 
(Weatherby, 1929). Doyle and Harding (1937) found Glaucoma ex- 
creting ammonia, and not urea. Carbon dioxide is obviously ex- 
creted by the body surface as well as the contractile vacuole. At 
present the composition of the fluid in the contractile vacuole is not 
know 7 n. General reference (Weatherby, 1941); permeability of water 
in Protozoa (Belda, 1942; L0vtrup and Pigon, 1951); physiology of 
contractile vacuole (Stempell, 1924; Fortner, 1926; Gaw, 1936; 
Kitching, 1938a). 

Aside from the soluble forms, there often occur in the protozoan 
body insoluble substances in the forms of crystals and granules of 
various kinds. Schewiakoff (1894) first noticed that Paramecium 
often contained crystals (Fig. 43) composed of calcium phosphate, 
which disappeared completely in 1-2 days when the organisms were 
starved, and reappeared when food was given. Schewiakoff did not 
see the extrusion of these crystals, but considered that these crystals 


were first dissolved and excreted by the contractile vacuoles, as they 
were seen collected around the vacuoles. When exposed to X-irradi- 
ation, the symbiotic Chlorella of Paramecium bursaria disappear 
gradually and crystals appear and persist in the cytoplasm of the 
ciliate (Wichterman, 1948a). These crystals varying in size from a 
few to 12m, are found mainly in the posterior region of the body. 
Wichterman notes that the appearance or disappearance of crystals 
seems to be correlated with the absence or presence of symbiotic 
Chlorella and with the holozoic or holophytic (by the alga) nutrition 
of the organism. 

In Amoeba proteus, Schubotz (1905) noted crystals of calcium 
phosphate which were bipyramidal or rhombic in form, were doubly 
refractile and measured about 2-5m in length. In three species of 
Amoeba, Schaeffer (1920) points out the different shape, number and 
dimensions of the crystals. Thus in Amoeba proteus, they are truncate 
bipyramids, rarely flat plates, up to 4.5m long; in A. discoides, abun- 
dant, truncate bipyramids, up to 2.5m long; and in .4. dubia, vari- 
ously shaped (4 kinds), few, but large, up to 10m, 12m, 30m long (Fig. 
43). Bipyramidal or plate-like crystals are especially abundant in 
Pelom.yxa illinoisensis at all times (Kudo, 1951); the crystals of P. 
carolinensis remain the same during the starvation of the organism 
(Andresen and Holter, 1945; Holter, 1950). 

The crystals present in Protozoa appear to be of varied chemical 
nature. Luce and Pohl (1935) noticed that at certain times amoe- 
bae in culture are clear and contain relatively a few crystals but, as 
the culture grows older and the water becomes more neutral, the 
crystals become abundant and the organisms become opaque in 
transmitted light. These crystals are tubular and six-sided, and vary 
in length from 0.5 to 3.5m- They considered the crystals were com- 
posed of calcium chlorophosphate. Mast and Doyle (1935), on the 
other hand, noted in Amoeba proteus two kinds of crystals, plate- 
like and bipyramidal, which vary in size up to 7m in length and 
which are suspended in alkaline fluid to viscous vacuoles. These two 
authors believed that the plate-like crystals are probably leucine, 
while the bipyramidal crystals consist of a magnesium salt of a sub- 
stituted glycine. Other crystals are said to be composed of urate, 
carbonate, oxalate, etc. 

Another catabolic product is the haemozoin (melanin) grains 
which occur in many haemosporidians and which appear to be com- 
posed of a derivative of the haemoglobin of the infected erythrocyte 
(p. 605). In certain Radiolaria, there occurs a brownish amorphous 
mass which is considered as catabolic waste material and, in Foram- 


inifera, the cytoplasm is frequently loaded with masses of brown 
granules which appear also to be catabolic waste and are extruded 
from the body periodically. 

While intracellular secretions are usually difficult to recognize, 
because the majority remain in fluid form except those which pro- 
duce endoskeletal structures occurring in Foraminifera, Heliozoa, 
Radiolaria, certain parasitic ciliates, etc., the extracellular secretions 
are easily recognizable as loricae, shells, envelopes, stalks, collars, 
mucous substance, etc. Furthermore, many Protozoa secrete, as was 
stated before, certain substances through the pseudopodia, tentacles 
or trichocysts which possess paralyzing effect upon the preys. 


Protozoa move about by means of the pseudopodia, flagella, or 
cilia, which may be combined with internal contractile organellae. 

Movement by pseudopodia. Amoeboid movements have long been 
studied by numerous observers. The first attempt to explain the 
movement was made by Berthold (1886), who held that the differ- 
ence in the surface tension was the cause of amoeboid movements, 
which view was supported by the observations and experiments of 
Butschli (1894) and Rhumbler (1898). According to this view, when 
an amoeba forms a pseudopodium, there probably occurs a diminu- 
tion of the surface tension of the cytoplasm at that point, due to 
certain internal changes which are continuously going on within the 
body and possibly due to external causes, and the internal pressure of 
the cytoplasm will then cause the streaming of the cytoplasm. This 
results in the formation of a pseudopodium which becomes attached 
to the substratum and an increase in tension of the plasma-mem- 
brane draws up the posterior end of the amoeba, thus bringing about 
the movement of the whole body. 

Jennings (1904) found that the movement of Amoeba verrucosa 
(Fig. 44, a) could not be explained by the surface tension theory, 
since he observed "in an advancing amoeba substance flows for- 
ward on the upper surface, rolls over at the anterior edge, coming 
in contact with the substratum, then remains quiet until the body 
of the amoeba has passed over it. It then moves upward at the 
posterior end, and forward again on the upper surface, continuing 
in rotation as long as the amoeba continues to progress." Thus 
Amoeba verrucosa may be compared with an elastic sac filled with 
fluid. Dellinger (1906) studied the movement of Amoeba proteus, A. 
verrucosa and Difflugia spiralis. Studying in side view, he found 
that the amoeba (Fig. 45) extends a pseudopod, "swings it about, 



brings it into the line of advance, and attaches it" to the substratum 
and that there is then a concentration of the substance back of this 
point and a flow of the substance toward the anterior end. Dellinger 
held thus that "the movements of amoebae are due to the presence 

Fig. 44. a, diagram showing the movement of Amoeba verrucosa in side 
view (Jennings) • b, a marine limax-amoeba in locomotion (Pantin from 
Reichenow). ac, area of conversion; cet, contracting ectoplasmic tube; fe, 
fluid ectoplasm; ge, gelated ectoplasm. 

of a contractile substance," which was said to be located in the endo- 
plasm as a coarse reticulum. Wilber (1946) pointed out that Pelo- 
myxa carolinensis carries on a similar movement at times. 

Fig. 45. Outline sketches of photomicrographs of Amoeba protexis 
during locomotion, as viewed from side (Dellinger). 

In the face of advancement of our knowledge on the nature of 
protoplasm, Rhumbler (1910) realized the difficulties of the surface 
tension theory and later suggested that the conversion of the ecto- 
plasm to endoplasm and vice versa were the cause of the cytoplasmic 


movements, which was much extended by Hyman (1917). Hyman 
considered that: (1) a gradient in susceptibility to potassium cyanide 
exists in each pseudopodium, being the greatest at the distal end, 
and the most recent pseudopodium, the most susceptible; (2) the 
susceptibility gradient (or metabolic gradient) arises in the amoebae 
before the pseudopodium appears and hence the metabolic change 
which produces increased susceptibility, is the primary cause of 
pseudopodium formation; and (3) since the surface is in a state of 
gelation, amoeboid movement must be due to alterations of the col- 
loidal state. Solation, which is brought about by the metabolic 
change, is regarded as the cause of the extension of a pseudopodium, 
and gelation, of the withdrawal of pseudopodia and of active con- 
traction. Schaeffer (1920) mentioned the importance of the surface 
layer which is a true surface tension film, the ectoplasm, and the 
streaming of endoplasm in the amoeboid movement. 

Pantin (1923) studied a marine limax-type amoeba (Fig. 44, 6) and 
came to recognize acid secretion and absorption of water at the place 
where the pseudopodium was formed. This results in swelling of the 
cytoplasm and the pseudopodium is formed. Because of the acidity, 
the surface tension increases and to lower or reduce this, concentra- 
tion of substances in the "wall" of the pseudopodium follows. This 
leads to the formation of a gelatinous ectoplasmic tube which, as the 
pseudopodium extends, moves toward the posterior region where the 
acid condition is lost, gives up water and contracts finally becoming 
transformed into endoplasm near the posterior end. The contraction 
of the ectoplasmic tube forces the endoplasmic streaming to the 

This observation is in agreement with that of Mast (1923, 1926, 
1931) who after a series of carefully conducted observations on 
Amoeba proteus came to hold that the amoeboid movement is 
brought about by "four primary processes; namely, attachment to 
the substratum, gelation of plasmasol at the anterior end, solation of 
plasmagel at the posterior end and the contraction of the plasmagel 
at the posterior end" (Fig. 46). As to how these processes work, 
Mast states: "The gelation of the plasmasol at the anterior end ex- 
tends ordinarily the plasmagel tube forward as rapidly as it is broken 
down at the posterior end by solation and the contraction of the 
plasmagel tube at the posterior end drives the plasmasol forward. 
The plasmagel tube is sometimes open at the anterior end and the 
plasmasol extends forward and comes in contact with the plasma- 
lemma at this end (Fig. 47, a), but at other times it is closed by a 
thin sheet of gel which prevents the plasmasol from reaching the 



Fig. 46. Diagram of Amoeba proteus, showing the solation and gelation 
ot the cytoplasm during amoeboid movement (Mast), c, crystal: cv con- 
tractile vacuole; f food vacuole; he, hyaline cap; n, nucleus; pg plasma- 
gel; pgs, plasmagel sheet; pi, plasmalemma; ps, plasmasol 



anterior end (6). This gel sheet at times persists intact for consider- 
able periods, being built up by gelation as rapidly as it is broken 
down by stretching, owing to the pressure of the plasmagel against 
it. Usually it breaks periodically at various places. Sometimes the 
breaks are small and only a few granules of plasmasol pass through 
and these gelate immediately and close the openings (d). At other 
times the breaks are large and plasmasol streams through, filling the 
hyaline cap (c), after which the sol adjoining the plasmalemma gel- 

Fig. 47. Diagrams of varied cytoplasmic movements at the tip of a 
pseudopodium in Amoeba proteus (Mast), g, plasmagel; he, hyaline cap; 
hi, hyaline layer; pi, plasmalemma; s, plasmasol. 

ates forming a new gel sheet. An amoeba is a turgid system, and the 
plasmagel is under continuous tension. The plasmagel is elastic and, 
consequently, is pushed out at the region where its elasticity is 
weakest and this results in pseudopodial formation. When an amoeba 
is elongated and undergoing movement, the elastic strength of the 
plasmagel is the highest at its sides, lowest at the anterior end and 
intermediate at the posterior end, which results in continuity of the 
elongated form and in extension of the anterior end. If pressure is 
brought against the anterior end, the direction of streaming of plas- 
masol is immediately reversed, and a new hyaline cap is formed at 
the posterior end which is thus changed into a new anterior end." 
The rate of amoeboid locomotion appears to be influenced by en- 
vironmental factors such as pH, osmotic pressure, salt concentration, 
substratum, temperature, etc. (Mast and Prosser, 1932). 

Flagellar movement. The flagellar movement is in a few instances 
observable as in Peranema, but in most cases it is very difficult to 
observe in life. Since there is difference in the number, location, size, 
and probably structure (p. 53) of flagella occurring in Protozoa, it 
is supposed that there are varieties of flagellar movements. The first 
explanation was advanced by Biitschli, who observed that the flagel- 


lum undergoes a series of lateral movements and, in so doing, a pres- 
sure is exerted on the water at right angles to its surface. This pres- 
sure can be resolved into two forces: one directed parallel, and the 
other at right angles, to the main body axis. The former will drive 
the organism forward, while the latter will tend to rotate the animal 
on its own axis. 

Gray (1928), who gave an excellent account of the movement of 
flagella, points out that "in order to produce propulsion there must 
be a force which is always applied to the water in the same direction 
and which is independent of the phase of lateral movement. There 
can be little doubt that this condition is satisfied in flagellated organ- 
isms not because each particle of the flagellum is moving laterally to 
and fro, but by the transmission of the waves from one end of the 
flagellum to the other, and because the direction of the transmission 
is always the same. A stationary wave, as apparently contemplated 
by Biitschli, could not effect propulsion since the forces acting on 
the water are equal and opposite during the two phases of the move- 
ment. If however the waves are being transmitted in one direction 
only, definite propulsive forces are present which always act in a 
direction opposite to that of the waves." 

Because of the nature of the flagellar movement, the actual proc- 
ess has often not been observed. Verworn observed long ago that in 
Peranema trichophorum the undulation of the distal portion of flagel- 
lum is accompanied by a slow forward movement, while undulation 
along the entire length is followed by a rapid forward movement. 
Krijgsman (1925) studied the movements of the long flagellum of 
Monas sp. (Fig. 48) which he found in soil cultures, under the dark- 
field microscope and stated: (1) when the organism moves forward 
with the maximum speed, the flagellum starting from c 1, with the 
wave beginning at the base, stretches back (c 1-6), and then waves 
back (d, e), which brings about the forward movement. Another type 
is one in which the flagellum bends back beginning at its base (/) 
until it coincides with the body axis, and in its effective stroke waves 
back as a more or less rigid structure (g) ; (2) when the organism 
moves forward with moderate speed, the tip of the flagellum passes 
through 45° or less (h-j) ; (3) when the animal moves backward, the 
flagellum undergoes undulation which begins at its base (k-o) ; (4) 
when the animal moves to one side, the flagellum becomes bent at 
right angles to the body and undulation passse along it from its base 
to tip (p); and (5) when the organism undergoes a slight lateral 
movement, only the distal end of the flagellum undulates (q). 

Ciliary movement. The cilia are the locomotor organella present 



permanently in the ciliates and vary in size and distribution among 
different species. Just as flagellates show various types of move- 
ments, so do the ciliates, though nearly all free-swimming forms 
swim in a spiral path (Bullington, 1925, 1930). Individual cilium on a 

Fig. 48. Diagrams illustrating flagellar movements of Monas sp. 
(Krijgsman). a-g, rapid forward movement (a, b, optical image of the 
movement in front and side view; c, preparatory and d, e, effective stroke; 
f, preparatory and g, effective stroke); h-j, moderate forward movement 
(h, optical image; i, preparatory and j, effective stroke); k-o, undulatory 
movement of the flagellum in backward movement; p, lateral movement; 
q, turning movement. 



progressing ciliate bends throughout its length and strikes the water 
so that the organism tends to move in a direction opposite to that of 
the effective beat, while the water moves in the direction of the beat 
(Fig. 49, a-d). In the Protociliata and the majority of holotrichous 
and heterotrichous ciliates, the cilia are arranged in longitudinal, or 
oblique rows and it is clearly noticeable that the cilia are not beating 
in the same phase, although they are moving at the same rate. A 

/" "^ 7 

1 2 

'5 4 



Fig. 49. Diagrams illustrating ciliary movements (Verworn). a-d, 
movement of a marginal cilium of Urostyla grandis (a, preparatory and 
b, effective stroke, resulting in rapid movement; c, preparatory, and d, 
effective stroke, bringing about moderate speed) ; e, metachronous move- 
ments of cilia in a longitudinal row. 

cilium (Fig. 49, e) in a single row is slightly in advance of the cilium 
behind it and slightly behind the one just in front of it, thus the cilia 
on the same longitudinal row beat metachronously. On the other 
hand, the cilia on the same transverse row beat synchronously, the 
condition clearly being recognizable on Opalina among others, 
which is much like the waves passing over a wheat field on a windy 
day. The organized movements of cilia, cirri, membranellae and un- 
dulating membranes are probably controlled by the neuromotor 
system (p. 63) which appears to be conductile as judged by the 
results of micro-dissection experiments of Taylor (p. 65). Ciliary 
movement (Gray, 1928) ; spiral movement of ciliates (Bullington, 
1925, 1930); movement of Paramecium (Dembowski, 1923, 1929a) 
and of Spirostomum (Blattner, 1926). 

The Protozoa which possess myonemes are able to move by con- 


traction of the body or of the stalk, and others combine this with the 
secretion of mucous substance as is found in Haemogregarina and 


Under natural conditions, the Protozoa do not behave always in 
the same manner, because several stimuli act upon them usually in 
combination and predominating stimulus or stimuli vary under dif- 
ferent circumstances. Many investigators have, up to the present 
time, studied the reactions of various Protozoa to external stimula- 
tions, full discussion of which is beyond the scope of the present 
work. Here one or two examples in connection with the reactions 
to each of the various stimuli only will be mentioned. Of various 
responses expressed by a protozoan against a stimulus such as 
changes in body form, movement, structure, behavior, etc., the 
movement is the most clearly recognizable one and, therefore, free- 
swimming forms, particularly ciliates, have been the favorite ob- 
jects of study. We consider the reaction to a stimulus in protozoans 
as the movement response, and this appears in one of the two direc- 
tions: namely, toward, or away from, the source of the stimulus. 
Here we speak of positive or negative reaction. In forms such as 
Amoeba, the external stimulation is first received by the body sur- 
face and then by the whole protoplasmic body. In flagellated or 
ciliated Protozoa, the flagella or cilia act in part sensory; in fact in a 
number of ciliates are found non-vibratile cilia which appear to be 
sensory in function. In a comparatively small number of forms, there 
are sensory organellae such as stigma, ocellus, statocysts, concretion 
vacuoles, etc. 

In general, the reaction of a protozoan to any external stimulus 
depends upon its intensity so that a certain chemical substance may 
bring about entirely opposite reactions on the part of the protozoans 
in different concentrations and, even under identical conditions, 
different individuals of a given species may react differently. Irri- 
tability (Jennings, 1906; Mast, 1941); in Spirostomum (Blattner, 

Reaction to mechanical stimuli. One of the most common stimuli 
a protozoan would encounter in the natural habitat is that which 
comes from contact with a solid object. When an amoeba which 
Jennings observed, came in contact with the end of a dead algal 
filament at the middle of its anterior surface (Fig. 50, a), the amoe- 
boid movements proceeded on both sides of the filament (6), but 
soon motion ceased on one side, while it continued on the other, and 



the organism avoided the obstacle by reversing a part of the current 
and flowing in another direction (c) . When an amoeba is stimulated 
mechanically by the tip of a glass rod (rf), it turns away from the 
side touched, by changing endoplasmic streaming and forming new 
pseudopodia (e). Positive reactions are also often noted, when a 
suspended amoeba (/) comes in contact with a solid surface with the 
tip of a pseudopodium, the latter adheres to it by spreading out (g). 
Streaming of the cytoplasm follows and it becomes a creeping form 

Fig. 50. Reactions of amoebae to mechanical stimuli (Jennings), a-c, 
an amoeba avoiding an obstacle; d, e, negative reaction to mechanical 
stimulation; f-h, positive reaction of a floating amoeba. 

(h). Positive reactions toward solid bodies account of course for the 
ingestion of food particles. 

In Paramecium, according to Jennings, the anterior end is more 
sensitive than any other parts, and while swimming, if it comes in 
contact with a solid object, the response may be either negative or 
positive. In the former case, avoiding movement (Fig. 51, c) follows 
and in the latter case, the organism rests with its anterior end 
or the whole side in direct contact with the object, in which position 
it ingests food particles through the cytostome. 

Reaction to gravity. The reaction to gravity varies among dif- 
ferent Protozoa, according to body organization, locomotor organ- 
elle, etc. Amoebae, Testacea and others which are usually found 
attached to the bottom of the container, react as a rule positively 



toward gravity, while others manifest negative reaction as in the 
case of Paramecium (Jensen; Jennings), which explains in part why 
Paramecium in a culture jar are found just below the surface film in 
mass, although the vertical movement of P. caudatum is undoubt- 
edly influenced by various factors (Koehler, 1922, 1930; Dembowski, 
1923, 1929, 1929a; Merton, 1935). 

Reaction to current. Free-swimming Protozoa appear to move 
or orientate themselves against the current of water. In the case of 

Fig. 51. Reactions of Paramecium (Jennings), a, collecting in a drop 
of 0.02% acetic acid; b, ring-formation around a drop of a stronger solu- 
tion of the acid; c, avoiding reaction. 

Paramecium, Jennings observed the majority place themselves in 
line with the current, with anterior end upstream. The mycetozoan 
is said to exhibit also a well-marked positive reaction. 

Reaction to chemical stimuli. When methylgreen, methylene 
blue, or sodium chloride is brought in contact with an advancing 
amoeba, the latter organism reacts negatively (Jennings). Jen- 
nings further observed various reactions of Paramecium against 
chemical stimulation. This ciliate shows positive reaction to weak 
solutions of many acids and negative reactions above certain con- 
centrations. For example, Paramecium enters and stays within the 


area of a drop of 0.02 per cent acetic acid introduced to the prepara- 
tion (Fig. 51, a); and if stronger acid is used, the organisms collect 
about its periphery where the acid is diluted by the surrounding 
water (b) . The reaction to chemical stimuli is probably of the great- 
est importance for the existence of Protozoa, since it leads them to 
proper food substances, the ingestion of which is the foundation of 
metabolic activities. In the case of parasitic Protozoa, possibly the 
reaction to chemical stimuli results in their finding specific host ani- 
mals and their distribution in different organs and tissues within the 
host body. Recent investigations tend to indicate that chemotaxis 
plays an important role in the sexual reproduction in Protozoa. 
Chemotaxis in Peranema (Chen, 1950). 

Reaction to light stimuli. Most Protozoa seem to be indifferent 
to the ordinary light, but when the light intensity is suddenly in- 
creased, there is usually a negative reaction. Verworn saw the di- 
rection of movements of an amoeba reversed when its anterior end 
was subjected to a sudden illumination; Rhumbler observed that an 
amoeba, which was in the act of feeding, stopped feeding when it 
was subjected to strong light. According to Mast, Amoeba pro- 
teus ceases to move when suddenly strongly illuminated, but con- 
tinues to move if the increase in intensity is gradual and if the il- 
lumination remains constant, the amoeba begins to move. Pelomyxa 
carolinensis reacts negatively to light (Kudo, 1946). 

The positive reaction to light is most clearly shown in stigma- 
bearing Mastigophora, as is well observable in a jar containing 
Euglena, Phacus, etc., in which the organisms collect at the place 
where the light is strongest. If the light is excluded completely, 
the organisms become scattered throughout the container, inac- 
tive and sometimes encyst, although the mixotrophic forms would 
continue activities by saprozoic method. The positive reaction to 
light by chromatophore-bearing forms enables them to find places 
in the water where photosynthesis can be carried on to the maximum 

All Protozoa seem to be more sensitive to ultraviolet rays. Inman 
found that amoeba shows a greater reaction to the rays than others 
and Hertel observed that Paramecium which was indifferent to an 
ordinary light, showed an immediate response (negative reaction) to 
the rays. MacDougall brought about mutations in Chilodonella by 
means of these rays (p. 229). Horvath (1950) exposed Kahlia sim- 
plex to ultraviolet rays and destroyed the micronucleus. The emi- 
cronucleate individuals lived and showed a greater vitality than nor- 
mal individuals, as judged by the division rate at 34°C. Mazia and 


Hirshfield (1951) subjected Amoeba proteus to ultraviolet radiation 
and noticed that irradiation of the whole and nucleated half amoebae 
delays division immediately following exposure; later progeny of the 
irradiated amoebae have a normal division rate; amputation of half 
of the cytoplasm greatly increases the radiation sensitivity as meas- 
ured by delayed division or by the dose required for permanent in- 
hibition of division (sterilization dose) ; individuals that have re- 
ceived this dose may survive for 20-30 days; and the survival time 
of an enucleate fragment is very much reduced by small (200-500 
ergs/sq. mm) doses. The two workers consider that the overall radia- 
tion effect may have both nuclear and cytoplasmic components. By 
exposing Pelomyxa carolinensis to 2537 A ultraviolet irradiation, 
Wilber and Slane (1951) found the effects variable; however, all re- 
covered from a two minutes' exposure, none survived a 10-minute 
exposure, and 70 per cent of fat were released after two minutes' 

Zuelzer (1905) found the effect of radium rays upon various Pro- 
tozoa vary; in all cases, a long exposure was fatal to Protozoa, the 
first effect of exposure being shown by accelerated movement. Hal- 
berstaedter and Luntz (1929, 1930) studied injuries and death of 
Eudorina elegans by exposure to radium rays. Entamoeba histolytica 
in culture when subjected to radium rays, Nasset and Kofoid (1928) 
noticed the following changes: the division rate rose two to four 
times by the exposure, which effect continued for not more than 24 
hours after the removal of the radium and was followed by a re- 
tardation of the rate; radium exposure produced changes in nuclear 
structure, increase in size, enucleation or autotomy, which were more 
striking when a larger amount of radium was used for a short time 
than a smaller amount acting on for a long time; and the effects 
persisted for four to six days after the removal of the radium and 
then the culture gradually returned to normalcy. Halberstaedter 
(1914) reported that when exposed to Beta rays, Trypanosoma 
brucei lost its infectivity, though remained alive. 

Halberstaedter (1938) exposed Trypanosoma gambiense to X-rays 
and found that 12,000r rendered the organisms not infectious for 
mice, while 600,000r was needed to kill the flagellates. Emmett 
(1950) exposed T. cruzi to X-rays and noticed that dosages between 
51,000r and 100,000r were necessary to destroy the infectivity of this 
trypanosome; the cultures, after exposure to 100,000r, appeared to 
be thriving up to three months; and the effects of exposure were not 
passed on to new generations. 

When Paramecium bursaria were exposed to X-rays, Wichterman 


(1948) noted: dosages higher than 100,0Q0r retard the locomotion of 
the ciliate; none survives 700,000r; the symbiotic Chlorella is de- 
stroyed by exposure to 300,000-000,000?' ; irradiation inhibits di- 
division temporarily, but the animals recover normal division rate 
after certain length of time; and mating types are not destroyed, 
though minor changes occur. In Pelomyxa carolinensis, Daniels 
(1951) observed: the median lethal dose of X-rays is 96,000r; with 
dosages 15,000-140,000r, the first plasmotomy is greatly delayed and 
the second plasmotomy is also somewhat delayed, but later plas- 
motomies show complete recovery; X-irradiation does not change 
the type of plasmotomy; and in individuals formed by plasmogamy 
of X-irradiated halves to non-irradiated halves, the nuclei divide 
simultaneously as in a normal individual. 

Reaction to temperature stimuli. As was stated before, there 
seems to be an optimum temperature range for each protozoan, 
although it can withstand temperatures which are lower or higher 
than that range. As a general rule, the higher the temperature, the 
greater the metabolic activities, and the latter condition results in 
turn in a more rapid growth and more frequent reproduction. It has 
been suggested that change to different phases in the life-cycle of a 
protozoan in association with the seasonal change may be largely 
due to temperature changes of the environment. In the case of 
parasitic Protozoa which inhabit two hosts: warm-blooded and cold- 
blooded animals, such as Plasmodium and Leishmania, the difference 
in body temperature of host animals may bring about specific stages 
in their development. 

Reaction to electrical stimuli. Since Verworn's experiments, 
several investigators studied the effects of electric current which 
is passed through Protozoa in water. Amoeba shows negative re- 
action to the anode and moves toward the cathode either by revers- 
ing the cytoplasmic streaming (Verworn) or by turning around the 
body (Jennings). The free-swimming ciliates move mostly toward 
the cathode, but a few may take a transverse position (Spirostomum) 
or swim to the anode (Paramecium, Stentor, etc.). Of flagellates, 
Verworn noticed that Trachelomonas and Peridinium moved to the 
cathode, while Chilomonas, Cryptomonas, and Polytomella, swam 
to the anode. When Paramecium caudatum was exposed to a high- 
frequency electrostatic or electromagnetic field, Kahler, Chalkley 
and Voegtlin (1929) found the effect was primarily caused by a tem- 
perature increase in the organism. By subjecting Pelomyxa carolin- 
ensis to a direct current electric field, Daniel and May (1950) noted 
that the time required for the rupture of the body in a given current 


density is directly correlated with the size of the organism and that 
calcium increases the time required for rupture at a fixed body size 
and current density, but does not alter the size effect. Galvanotaxis 
of Oxytricha (Luntz, 1935), of Arcella (Miller, 1932). 


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(1929a) II. Ibid., 68:215. 

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— (1930) Weitere Untersuchungen ueber die Wirkung 
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(1930) II. Ibid., 70:279. 

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Chapter 5 

THE mode of reproduction in Protozoa is highly variable among 
different groups, although it is primarily a cell division. The 
reproduction is initiated by the nuclear division in nearly all cases, 
which will therefore be considered first. 

Nuclear division 

Between a simple direct division on the one hand and a com- 
plicated indirect division which is comparable with the typical 
metazoan mitosis on the other hand, all types of nuclear division 

Direct nuclear division. Although not so widely found as it was 
thought to be in former years, amitosis occurs normally and regu- 
larly in many forms. While the micronuclear division of the Cilio- 
phora is mitotic (p. 165), the macronuclear division is invariably 
amitosis. The sole exception to this general statement appears to be 
the so-called promitosis reported by Ivanic (1938) in the macro- 
nucleus in the "Vermehrungsruhe" stage of Chilodenella uncinata in 
which chromosomes and spindle-fibers were observed. In Para- 
mecium caudatum (Fig. 52), the micronucleus initiates the division 
by mitosis and the macronucleus elongates itself without any visible 
changes in its internal structure. The elongated nucleus becomes 
constricted through the middle and two daughter nuclei are pro- 

It is assumed that the nuclear components undergo solation during 
division, since the formed particles of nucleus which are stationary 
in the resting stage manifest a very active Brownian movement. 
Furthermore, in some cases the nuclear components may undergo 
phase reversal, that is to say, the chromatin granules which are dis- 
persed phase in the non-staining fluid dispersion medium in the rest- 
ing nucleus, become dispersion medium in which the latter is sus- 
pended as dispersed phase. By using Feulgen's nucleal reaction, 
Reichenow (1928) demonstrated this reversal phenomenon in the di- 
vision of the macronucleus of Chilodonella cucullulus (Fig. 53). 

The macronucleus becomes at the time of its division somewhat 
enlarged and its chromatin granules are more deeply stained than 
before. But chromosomes which characterize the mitotic division 
are entirely absent, although in a few forms in which mating types 
occur, the type difference and certain other characters, according to 




Sonneborn and Kimball, appear to be under control of genie consti- 
tuents of the macronucleus. Since the number of chromatin granules 
appear approximately the same in the macronuclei of different gen- 
erations of a given species, the reduced number of chromatin gran- 

Fig. 52. Nuclear and cytoplasmic division of Paramecium caudatum as 
seen in stained smears, X260 (Kudo). 

ules must be restored sometime before the next division takes place. 
Calkins (1926) is of the opinion that "each granule elongates and 
divides into two parts, thus doubling the number of chromomeres." 
Reichenow (1928) found that in Chilodonella cucullulus the lightly 
Feulgen positive endosome appeared to form chromatin granules 
and Kudo (1936) maintained that the large chromatin spherules of 



the macronucleus of Nyctotherus ovalis probably produce smaller 
spherules in their alveoli (Fig. 3). 

When the macronucleus is elongated as in Spirostomum, Stentor. 
Euplotes, etc., the nucleus becomes condensed into a rounded form 
prior to its division. During the "shortening period" of the elongated 
macronuclei prior to division, there appear 1-3 characteristic zones 
which have been called by various names, such as nuclear clefts, 
reconstruction bands, reorganization bands, etc. In Euplotes patella 

Fig. 53. The solation of chromatin during the macronuclear division of 
Chilodonella cucullulus, as demonstrated by Feulgen's nucleal reaction, 

(E. eury stomas) , Turner (1930) observed prior to division of the 
macronucleus a reorganization band consisting of a faintly staining 
zone ("reconstruction plane") and a deeply staining zone ("solution 
plane"), appears at each end of the nucleus (Fig. 54, a) and as each 
moves toward the center, a more chromatinic area is left behind 
(b-d). The two bands finally meet in the center and the nucleus as- 
sumes an ovoid form. This is followed by a simple division into two. 
In the T-shaped macronucleus of E. woodruffi, according to Pierson 
(1943), a reorganization band appears first in the right arm and the 
posterior tip of the stem of the nucleus. When the anterior band 
reaches the junction of the arm and stem, it splits into two, one part 



moving along the left arm to its tip, and the other entering and pass- 
ing down the stem to join the posterior band. According to Summers 
(1935) a process similar to that of E. eurystomus occurs in Diophrys 
appendiculata and Stylonychia pustulata; but in Aspidisca lynceus 
(Fig. 55) a reorganization band appears first near the middle region 
of the macronucleus (6), divides into two and each moves toward an 
end, leaving between them a greater chromatinic content of the 
reticulum (c-i). Summers suggested that "the reorganization bands 
are local regions of karyolysis and resynthesis of macronuclear 
materials with the possibility of an elimination of physically or 
possibly chemically modified nonstaining substances into the cyto- 
plasm." Weisz (1950a) finds that the nodes of the moniliform macro- 

Fig. 54. Macronuclear reorganization before division in Euplotes 
eurystomus, X240 (Turner), a, reorganization band appearing at a tip 
of the macronucleus; b-d, later stages. 

nucleus of Stentor coeruleus contain different concentration of thymo- 
nucleic acid which is correlated with morphogenetic activity of indi- 
vidual nodes, and that fusion of ill-staining nodes results in a return 
of strong affinity to methyl green. It appears, therefore, concentra- 
tion of bandform or moniliform macronucleus prior to division may 
serve to recover morphogenetic potential prior to division. 

In a small number of ciliates, the macronucleus is distributed as 
small bodies throughout the cytoplasm. In Urostyla grandis, the 
macronuclear material is lodged in 100 or more small bodies scat- 
tered in the cytoplasm. Prior to fission, all macronuclear bodies fuse 
with one another and form one macronucleus which then divides 
three times into eight and the latter are evenly distributed between 
the two daughter individuals, followed by divisions until the number 
reaches 100 or more (Raabe, 1947). On the other hand, in Dileptus 



anser (Fig. 310, c), "each granule divides where it happens to be 
and with the majority of granules both halves remain in one daugh- 
ter cell after division" (Calkins). Hayes noticed a similar division, 
but at the time of simultaneous division prior to cell division, each 
macronucleus becomes elongated and breaks into several small 

Fig. 55. Macronuclear reorganization prior to division in Aspidisca 
lynceus, X1400 (Summers), a, resting nucleus; b-i, successive stages in 
reorganization process; j, a daughter macronucleus shortly after division. 

The extrusion of a certain portion of the macronuclear material 
during division has been observed in a number of species. In Urolep- 
tus halseyi, Calkins actually noticed each of the eight macronuclei 
is "purified" by discarding a reorganization band and an "x-body" 
into the cytoplasm before fusing into a single macronucleus which 
then divides into two nuclei. In the more or less rounded macro- 
nucleus that is commonly found in many ciliates, no reorganization 
band has been recognized. A number of observers have however noted 



that during the nuclear division there appears and persists a small 
body within the nuclear figure, located at the division plane as in 
the case of Loxocephalus (Behrend), Eupoterion (MacLennan and 
Connell) and even in the widely different protozoan, Endamoeba 
blattae (Kudo, 1926). Kidder (1933) observed that during the division 
of the macronucleus of Conchophthirus my till (Fig. 56), the nucleus 
"casts out a part of its chromatin at every vegetative division," 
which "is broken down and disappears in the cytoplasm of either 

Fig. 56. Macronuclear division in Conchophthirus mytili, X440 (Kidder). 

daughter organism." A similar phenomenon has since been found 
further in C. anodontae, C. curtus, C. magna (Kidder), Urocentrum 
turbo, Colpidium colpoda, C. campylum, Glaucoma scintillans (Kidder 
and Diller), Allosphaerium convexa (Kidder and Summers), Colpoda 
inHata, C. maupasi, Tillina canalifera, Bresslaua vorax, etc. (Burt et 
al., 1941). Beers (1946) noted chromatin extrusion from the macro- 
nucleus during division and in permanent cysts in Tillina magna. 
What is the significance of this phenomenon? Kidder and his associ- 
ates believe that the process is probably elimination of waste sub- 
stances of the prolonged cell-division, since chromatin extrusion does 
not take place during a few divisions subsequent to reorganization 


after conjugation in Conchophthirus mytili and since in Colpidium 
and Glaucoma, the chromatin elimination appears to be followed by 
a high division rate and infrequency of conjugation. Dass (1950) 
noticed a dark body between two daughter macronuclei of a ciliate 
designated by him as Glaucoma piriformis and considered it as sur- 
plus desoxyribonucleic acid about to be converted by the cytoplasm 
to ribonucleic acid necessary for active growth. 

In Paramecium aurelia, Woodruff and Erdmann (1914) reported 
the occurrence of "endomixis." At regular intervals of about 30 days, 
the old macronucleus breaks down and disappears, while each of the 
two micronuclei divides twice, forming eight nuclei. Of these, six 
disintegrate. The animal then divides into two, each daughter indi- 
vidual receiving one micronucleus. This nucleus soon divides twice 
into four, two of which develop into two macronuclei, while the 
other two divide once more. Here the organism divides again into 
two individuals, each bearing one macronucleus and two micronuclei. 
This process, they maintained, is "a complete periodic nuclear re- 
organization without cell fusion in a pedigreed race of Paramecium." 
The so-called endomixis has since been reported to occur in many 
ciliates. However, as pointed out by Wilson (1928), Diller (1936), 
Sonneborn (1947) and others, there are several difficulties in holding 
that endomixis is a valid process. Diller considers that endomixis 
may have been based upon partial observations on hemixis (p. 206) 
and autogamy (p. 203). Sonneborn could not find any indication 
that this process occurs in numerous stocks and varieties of Para- 
mecium aurelia, including the progeny of the strains studied by 
Woodruff, and maintained that endomixis does not occur in this spe- 
cies of Paramecium. 

As has been stated already, two types of nuclei: macronucleus 
and micronucleus, occur in Euciliata and Suctoria. The macro- 
nucleus is the center of the whole metabolic activity of the organism 
and in the absence of this nucleus, the animal perishes. The waste 
substances which become accumulated in the macronucleus through 
its manifold activities, are apparently eliminated at the time of 
division, as has been cited above in many species. On the other 
hand, it is also probable that under certain circumstances, the macro- 
nucleus becomes impregnated with waste materials which cannot be 
eliminated through this process. Prior to and during conjugation 
(p. 188) and autogamy (p. 203), the macronucleus becomes trans- 
formed, in many species, into irregularly coiled thread-like structure 
(Fig. 85) which undergoes segmentation into pieces and finally is 
absorbed by the cytoplasm. New macronuclei are produced from 



some of the division-products of micronuclei by probably incor- 
porating the old macronuclear material. In most cases this sup- 
position is not demonstrable. However, Kidder (1938) has shown in 

S'd © © 

d e f g 

Fig. 57. Diagram showing the macronuclear regeneration in Parame- 
cium aurelia (Sonneborn). a, an individual before the first division after 
conjugation or autogamy, containing two macronuclear (stippled) an- 
lagen, two micronuclei (rings) and about 30 disintegrating (solid black) 
masses of the old macronucleus; b, two individuals formed by the first 
division, each containing one macronuclear anlage, two micronuclei and 
macronuclear masses; c, two individuals produced by the second division: 
one (above) with the new macronucleus, two micronuclei and macro- 
nuclear masses, and the other without new macronucleus; d-f, binary 
fissions in which the two micronuclei divide, but old macronuclear masses 
are distributed equally between the two daughters until there is one large 
regenerated macronucleus and two micronuclei; g, division following f, 
goes on in an ordinary manner. 

the encysted Paraclevelandia simplex, an endocommensal of the 
colon of certain wood-feeding roaches, this is actually the case; 
namely, one of the divided micronuclei fuses directly with a part of 
macronucleus to form a macronuclear anlage which then develops 
into a macronucleus after passing through "ball-of-yarn" stage simi- 
lar to that which appears in an exconjugant of Nyctotherus (Fig. 85). 


Since the macro-nucleus originates in a micronucleus, it must con- 
tain all structures which characterize the micronucleus. Why then 
does it not divide mitotically as does the micronucleus? During 
conjugation or autogamy in a ciliate, the macronucleus degenerates, 
disintegrates and finally becomes absorbed in the cytoplasm. In 
Paramecium aurelia, Sonneborn (1940, 1942, 1947) (Fig. 57) ob- 
served that when the animal in conjugation is exposed to 38°C. 
from the time of the synkaryon-formation until before the second 
postzygotic nuclear division (a-c), the development of the two newly 
formed macronuclei is retarded and do not divide as usual with the 
result that one of the individuals formed by the second postzygotic 
division receives the newly formed macronucleus, while the other 
lacks this (c). In the latter, however, division continues, during 
which some of the original 20-40 pieces of the old macronucleus that 
have been present in the cytoplasm segregate in approximately equal 
number at each division (d, e) until there is only one in the animal 
(/). Thereafter the macronucleus divides at each division (g). Sonne- 
born found this "macronuclear regeneration" in the varieties 1 and 
4, but considered that it occurs in all stocks. Thus the macronucleus 
in this ciliate appears to be a compound structure with its 20-40 
component parts, each containing all that is needed for development 
into a complete macronucleus. From these observations, Sonneborn 
concludes that the macronucleus in P. aurelia appears to undergo 
amitosis, since it is a compound nucleus composed of many "sub- 
nuclei" and since at fission all that is necessary to bring about 
genetically equivalent functional macronuclei is to segregate these 
multiple subnuclei into two random groups. 

While the macronuclear division usually follows the micronuclear 
division, it takes place in the absence of the latter as seen in amicro- 
nucleate individuals of ciliates which possess normally a micronu- 
cleus. Amicronucleate ciliates have been found to occur naturally or 
produced experimentally in the following species: Didinium nasutum 
(Thon, 1905; Patten, 1921), Oxytricha hymenostoma (Dawson, 1919), 
O.fallax, Urostyla grandis (Woodruff , 1921), Paramecium caudatum 
(Landis, 1920; Woodruff, 1921), etc. Amicronucleate Oxytricha f alia x 
which were kept under observation by Reynolds (1932) for 29 
months, showed the same course of regeneration as the normal indi- 
viduals. Beers (1946b) saw no difference in vegetative activity be- 
tween amicronucleate and normal individuals of Tillina magna. In 
Euplotes patella, amicronucleates arise from "double" form (p. 229) 
with a single micronucleus, and Kimball (1941a) found that the 
mioronucleus is not essential for continued life in at least some 


clones, though its absence results in a marked decrease in vigor. The 
bi-micronucleate Paramecium bursaria which Woodruff (1931) iso- 
lated, developed in the course of 7 years of cultivation, unimicronu- 
cleate and finally amicronucleate forms, in which no marked varia- 
tion in the vitality of the race was observed. These data indicate that 
amicronucleates are capable of carrying on vegetative activity and 
multiplication, but are unable to conjugate or if cell-pairing occurs, 
the result is abortive, though Chen (1940c) reported conjugation be- 
tween normal and amicronucleate individuals of P. bursaria (p. 189). 
Horvath (1950) succeeded in destroying the micronucleus in Kahlia 
simplex (p. 133) and found the emicronucleates as vigorous as the 
normal forms, judged by the division rate, but were killed within 15 
days by proactinomycin, while normal individuals resisted by en- 
cystment. This worker reasons that the emicronucleates are easily 
destroyed by unfavorable conditions and, therefore, ciliates without 
a micronucleus occur rarely in nature. 

Fig. 58. Amitosis of the vegetative nucleus in the trophozoite of 
Myxosoma catostomi, X2250 (Kudo). 

Other examples of amitosis are found in the vegetative nuclei in 
the trophozoite of Myxosporidia, as for example, Myxosoma catos- 
tomi (Fig. 58), Thelohanellus notatus (Debaisieux), etc., in which the 
endosome divides first, followed by the nuclear constriction. In 
Streblomastix strix, the compact elongated nucleus was found to 
undergo a simple division by Kof oid and Swezy. 

Indirect nuclear division. The indirect division which occurs in the 
protozoan nuclei is of manifold types as compared with the mitosis 
in the metazoan cell, in which, aside from minor variations, the 
change is of a uniform pattern. Chatton, Alexeieff and others, have 
proposed several terms to designate the various types of indirect 
nuclear division, but no one of these types is sharply defined. For our 
purpose, mentioning of a few examples will suffice. 

A veritable mitosis was noted by Dobell in the heliozoan Oxnerella 
maritima (Fig. 59), which possesses an eccentrically situated nucleus 
containing a large endosome and a central centriole, from which 
radiate many axopodia (a). The first sign of the nuclear division is 



the slight enlargement, and migration toward the centriole, of the 
nucleus (6). The centriole first divides into two (c, d) and the nucleus 
becomes located between the two centrioles (e). Presently spindle 
fibers are formed and the nuclear membrane disappears (/, g). After 



••fin Hi' '».'. ' 

/ f'n 

Fig. 59. Nuclear and cytoplasmic division in Oxnerella maritime/,, X about 
1000 (Dobell). a, a living individual; b, stained specimen; c-g, prophase; 
h, metaphase; i, anaphase; j, k, telophase; 1, division completed. 

passing through an equatorial-plate stage, the two groups of 24 
chromosomes move toward the opposite poles (g-i). As the spindle 
fibers become indistinct, radiation around the centrioles becomes 
conspicuous and the two daughter nuclei are completely recon- 
structed to assume the resting phase (j-l). The mitosis of another 
heliozoan Acanthocystis aculeata is, according to Schaudinn and 



Stern, very similar to the above. Aside from these two species, the 
centriole has been reported in many others, such as Hartmannella 
(Arndt), Euglypha, Monocystis (Bglaf), Aggregata (Dobell; Bglaf; 

Fig. 60. Mitosis in Trichonympha campanula, X800 (Kofoid and 
Swezy). a, resting nucleus; b-g, prophase; h, metaphase; i, j, anaphase; 
k, telophase; 1, a daughter nucleus being reconstructed. 


Naville), various Hypermastigina (Kofoid; Duboscq and Grasse; 
Kirby; Cleveland and his associates). 

In numerous species the division of the centriole (or blepharo- 
plast) and a connecting strand between them, which has been called 
desmose (centrodesmose or paradesmose), have been observed. Ac- 
cording to Kofoid and Swezy (1919), in Trichonympha campanula 
(Fig. 60), the prophase begins early, during which 52 chromosomes 
are formed and become split. The nucleus moves nearer the anterior 
end where the centriole divides into two, between which develops a 
desmose. From the posterior end of each centriole, astral rays extend 
out and the split chromosomes form loops and pass through "tangled 
skein" stage. In the metaphase, the equatorial plate is made up of 
V-shaped chromosomes as each of the split chromosomes is still 
connected at one end, which finally becomes separate in anaphase, 
followed by reformation of two daughter nuclei. 

As to the origin and development of the achromatic figure, vari- 
ous observations and interpretations have been advanced. Certain 
Hypermastigina possess very large filiform centrioles and a large 
rounded nucleus. In Barbulanympha (Fig. 61), Cleveland (1938a) 
found that the centrioles vary from 15 to 30^ in length in the four 
species of the genus which he studied. They can be seen, according 
to Cleveland, in life as made up of a dense hyaline protoplasm. 
When stained, it becomes apparent that the two centrioles are 
joined at their anterior ends by a desmose and their distal ends 20 to 
30/x apart, each of which is surrounded by a special centrosome (a). 
In the resting stage no fibers extend from either centriole, but in the 
prophase, astral rays begin to grow out from the distal end of each 
centriole (6). As the rays grow longer (c), the two sets soon meet and 
the individual rays or fibers join, grow along one another and over- 
lap to form the central spindle (d). In the resting nucleus, there are 
large irregular chromatin granules which are connected by fibrils 
with one another and also with the nuclear membrane. As the achro- 
matic figure is formed and approaches the nucleus, the chromatin be- 
comes arranged in a single spireme imbedded in matrix. The spireme 
soon divides longitudinally and the double spireme presently breaks 
up transversely into paired chromosomes. The central spindle begins 
to compress the nuclear membrane and the chromosomes become 
shorter and move apart. The intra- and extra-nuclear fibrils unite as 
the process goes on (e), the central spindle now assumes an axial 
position, and two groups of V-shaped chromosomes are drawn to 
opposite poles. In the telophase, the chromosomes elongate and be- 
come branched, thus assuming conditions seen in the resting nucleus. 



Fig. 61. Development of spindle and astral rays during the mitosis in 
Barbulanympha, X930 (Cleveland), a, interphase centrioles and centro- 
somes; b, prophase centrioles with astral rays developing from their distal 
ends through the centrosomes; c, meeting of astral rays from two cen- 
trioles; d, astral rays developing into the early central spindle; e, a later 
stage showing the entire mitotic figure. 

In Holomastigotoides tusitala (Fig. 172, a, b), Cleveland (1949) 
brought to light the formation of the achromatic figure, and the 
minute structure and change in chromosomes (Fig. 62). In the late 
telophase, after cytoplasmic division, the centrioles follow the flagel- 
lar bands 4 and 5 for 1.5 turns (a). The two chromosomes are an- 
chored to the old centriole. When the new centriole has become as 



a M>, 

Fig. 62. Mitosis in Holomastigotoides tusitala (Cleveland), a, anterior 
region showing flagellar bands, centrioles, centromeres and chromosomes, 
b-h, telophase; i, j, prophase; k, metaphase; 1, anaphase; m, telophase, 
b, c, new and old centrioles forming achromatic figure; d, one chromosome 
has shifted its connection from old to new centriole; e, f, flattening out of 
centrioles and achromatic figure; g, h, beginning of chromosomal twist- 
ing; i, chromosomes duplicated, producing many gyres of close-together 
relational coiling of chromatics, and centromeres duplicated; j, chroma- 
tids losing their relational coiling by unwinding; k, relational coiling dis- 
appeared, achromatic figure elongating and separating sister chromatids; 
1, central spindle bent, chromatids in two groups; m, central spindle 
pulled apart. 


long as the old one, the centrioles begin to produce astral rays (b) 
which soon meet and form the central spindle (c). An astral ray from 
the new centriole becomes connected with the centromere of one of 
the chromosomes (d). The spindle grows in length and enters resting 
stage (e-j), later the spindle fibers lengthen (k, /) and pull apart (m). 

The chromosome is composed of the matrix and chromonema 
(Fig. 63), of which the former disintegrates in the telophase and re- 
appears in the early prophase of each chromosome generation, while 
the latter remains throughout. From late prophase to mid-telophase, 
minor coils are incorporated in major coils (a-c) ; from mid-telophase 
to late telophase, they are in very loose majors (d); and after the 
majors have disappeared completely, they become free (e). Soon 
after cytoplasmic division, the majors become looser and irregular 
and finally disappear, while minors and twisting remain. Each chro- 
mosome presently divides into 2 chromatids (f) and a new matrix is 
formed for each. As the matrix contracts the chromatids lose their 
relational coiling and the minors become bent and thus the new 
generation of major coils makes its appearance (g). With the further 
concentration of the matrix, the majors become more conspicuous 
(h), the minors being incorporated into them. When most of the re- 
lational coiling has been lost and majors are close together, the 
chromosomal changes cease for days or weeks. This is the late pro- 
phase. After the resting stage, the achromatic figure commences to 
grow again (i, j) and the two groups of chromatids are carried to the 
poles, followed by transverse cytoplasmic division (Fig. 64). The 
coils remain nearly the same during metaphase to early telophase. 
Thus Cleveland showed the continuity of chromosomes from genera- 
tion to generation. He finds that the resting stage of chromosomes 
varies in different types of cells: some chromosomes rest in inter- 
phase, some in early prophase and others in telophase, and that the 
centromere is an important structure associated with the movement 
of chromatids and in the reduction of chromosomes in meiosis. For 
fuller information the reader is referred to the profusely illustrated 
original paper (Cleveland, 1949). 

In Lophomonas blattarum, the nuclear division (Fig. 65) is initiated 
by the migration of the nucleus out of the calyx. On the nuclear 
membrane is attached the centriole which probably originates in the 
blepharoplast ring; the centriole divides and the desmose which 
grows, now stains very deeply, the centrioles becoming more con- 
spicuous in the anaphase when new flagella develop from them. 
Chromatin granules become larger and form a spireme, from which 



?, aft 

Fig. 63. Chromosomal changes in Holomastigotoides tusitala, X1050 
(Cleveland), a, telophase shortly after cytoplasmic division, new fifth 
band and new centriole are growing out and chromosomes are twisted; 
b, c, the same chromosome showing major and minor coils respectively; 
d, later telophase, showing minor coils; e, matrix completely disinte- 
grated, showing minor coils; f, a prophase nucleus, showing division of 
chromosomes into two chromatids; g, later prophase, in which majors 
are developing with minors; h, later prophase; i, metaphase in which 
distal halves of the chromatids have not yet separated, showing minor 
coils; j, anaphase, showing major and minor coils of chromonemata. 



Fig. 64. Cytoplasmic division in Holomastigotoides tusitala, X about 
430 (Cleveland), a, fifth flagellar band has separated from others; b, one 
nucleus and fifth band moving toward posterior end; c, the movement of 
the band and nucleus has been completed; d, e, anterior and posterior 
daughter individuals, produced by transverse division. 



6-8 chromosomes are produced. Two groups of chromosomes move 
toward the opposite poles, and when the division is completed, each 
centriole becomes the center of formation of all motor organellae. 

In some forms, such as Noctiluca (Calkins), Actinophrys (Belaf), 
etc., there may appear at each pole, a structureless mass of cyto- 
plasm (centrosphere), but in a very large number of species there 

Fig. 65. Nuclear division in Lophomonas blattarum, X1530 (Kudo), 
a, resting nucleus; b, c, prophase; d, metaphase; e-h, anaphase; i-k, telo- 

appear no special structures at poles and the spindle fibers become 
stretched seemingly between the two extremities of the elongating 
nuclear membrane. Such is the condition found in Pelomyxa (Kudo) 
(Fig. 66), Cryptomonas (Belaf), Rhizochrysis (Doflein), Aulacantha 
(Borgert), and in micronuclear division of the majority of Euciliata 
and Suctoria. 

The behavior of the endosome during the mitosis differs among 
different species as are probably their functions. In Eimeria schubergi 
(Schaudinn), Euglena viridis (Tschenzoff), Oxyrrhis marina (Hall), 



Colacium vesiculosum (Johnson), Haplosporidium limnodrili (Gran- 
ata), etc., the conspicuously staining endosome divides by elongation 
and constriction along with other chromatic elements, but in many 
other cases, it disappears during the early part of division and reap- 
pears when the daughter nuclei are reconstructed as observed in 
Monocystis, Dimorpha, Euglypha, Pamphagus (Belar), Acantho- 
cystis (Stern), Chilomonas (Doflein), Dinenympha (Kirby), etc. 

Fig. 66. Mitosis in Pelomyxa carolinensis, X1150 (Kudo), a, c, 1, in life; 
b, d-k, in acidified methyl green, a, b, resting nuclei; c-g, prophase; h, 
metaphase; i-k, anaphase; 1, front and side view of a young daughter 

In the vegetative division of the micronucleus of Conchophthirus 
anodontae, Kidder (1934) found that prior to division the micronu- 
cleus moves out of the pocket in the macronucleus and the chromatin 
becomes irregularly disposed in a reticulum; swelling continues and 
the chromatin condenses into a twisted band, a spireme, which 
breaks into many small segments, each composed of large chromatin 
granules. With the rapid development of the spindle fibers, the 
twelve bands become arranged in the equatorial plane and condense. 
Each chromosome now splits longitudinally and two groups of 12 
daughter chromosomes move to opposite poles and transform them- 



selves into two compact daughter nuclei. A detailed study of micro- 
nuclear division (Fig. 67) of Urostyla grandis was made by Raabe 
(1946). The micronucleus is a compact body in the interphase (a), 

Fig. 67. Micronuclear division of Urostyla grandis, X2100 (H. Raabe). 
a, resting stage; b-j, prophase (b-e, stages in the formation of spireme; 
f, g, spireme ribbon; h, i, twelve segments of ribbon arranged in the direc- 
tion of the elongating nuclear axis; j, a polar view of the same); k, 1, 
metaphase, condensation of the segments; m-o, anaphase; p, late ana- 
phase; q, a daughter nucleus in telophase; r-t, reconstruction stages; u, a 
resting daughter nucleus. 


but increases in size and the chromatin becomes grouped into small 
masses (6, c), which become associated into a spiral ribbon (d-g). 
The latter then breaks up into 12 segments that are arranged paral- 
lel to the axis of the elongating nucleus (h-i). Each segment con- 
denses into a chromosome which splits longitudinally into two (k) 
and the two groups of chromosomes move to opposite poles (l-P). In 
Zelleriella elliptica (Fig. 295) and four other species of the genus in- 
habiting the colon of Bufo valliceps, Chen (1936, 1948) observed the 
formation of 24 chromosomes, each of which is connected with a 
fiber of the intranuclear spindle and splits lengthwise in the meta- 

While in the majority of protozoan mitosis, the chromosomes split 
longitudinally, there are observations which suggest a transverse di- 
vision. As examples may be mentioned the chromosomal divisions in 
Astasia laevis (Belaf), Entosiphon sulcatum (Lackey), and a number 
of ciliates. In a small number of species observations vary within a 
species, as, for example, in Peranema trichophorum in which the 
chromosomes were observed to divide transversely (Hartmann and 
Chagas) as well as longitudinally (Hall and Powell; Brown). It is 
inconceivable that the division of the chromosome in a single species 
of organism is haphazard. The apparent transverse division might be 
explained by assuming, as Hall (1937) showed in Euglena gracilis, 
that the splitting is not completed at once and the pulling force act- 
ing upon them soon after division, brings forth the long chromo- 
somes still connected at one end. Thus the chromosomes remain to- 
gether before the anaphase begins. 

In the instances considered on the preceding pages, the so-called 
chromosomes found in them, appear to be essentially similar in 
structure and behavior to typical metazoan chromosomes. In many 
other cases, the so-called chromosomes or "pseudochromosomes" 
are slightly enlarged chromatin granules which differ from the ordin- 
ary chromatin granules in their time of appearance and movement 
only. In these cases it is of course not possible at present to deter- 
mine how and when their division occurs before separating to the 
respective division pole. In Table 5 are listed the number of the 
"chromosomes" which have been reported by various investigators 
in the Protozoa that are mentioned in the present work. 

Cytoplasmic division 

The division of the nucleus is accompanied by division of extranu- 
clear organelles such as chromatophores, pyrenoids, etc. The blepha- 
roplast of the flagellates and kinetosomes of the ciliates undergo di- 

Table 5. — Chromosomes in Protozoa 



Number of 


Rhizochrysis scherffeli 



H aematococcus pluvialis 



Polytomella agilis 



Chla7?iydomonas spp. 

10 (haploid) 


Polytoma uvella 

16 (diploid) 


Euglena pisciformis 



E. viridis 

30 or more 


Phacus pyrum 



Rhabdomonas incurva 

About 12 


Vacuolaria virescens 

About 30 


Syndinium turbo 



Anthophysis vegetans 



Cercomonas longicauda 



Collodictyon triciliatum 

About 20 


Chilomastix gallinarum 

About 12 

Boeck and Tanabe 

Eutrichomastix serpentis 


Kofoid and Swezy 

Dinenympha fimbricata 



Metadevescovina debilis 

About 4 


Trichomonas tenax 



T. gallinae 



T. hominis 

5 or 6 


T. vaginalis 



Tritrichomonas atigusta 


Kofoid and Swezy 

4 or 8 




T, batrachorum 

4 or 8 




T. muris 



Hexamita salmonis 

5 or 6 


Giardia intestinalis 


Kofoid and Swezy 

G. muris 


Kofoid and Christiansen 

Calonympha grassii 

4 or 5 


Spirotrichonympha polygyra 

2 doubles 




S. bispira 



Lophomonas blattarum 

16 or 8 doubles 


8 or 6 


12 or 6 doubles 


L. striata 

12 or 6 doubles 


Barbidanympha laurabuda 



B. uf alula 



Rhynchonympha tarda 



Urinympha talea 



Staurojoenia assimilis 



Trichony mpha campanula 

52 or 26 doubles 

Kofoid and Swezy 



Table 5. — Continued 


Number of 


T. grandis 



Plasmodiophora brassicae 

8 (diploid) 


Naegleria gruberi 



N. bistadialis 



Amoeba protevs 



Endamoeba disparata 

About 12 


Entamoeba histolytica 


Kofoid and Swezy; Uribe 

E. coli 


Swezy; Stabler 



E. gingivalis 


Stabler; Noble 

Dientamoeba fragilis 





Uydr amoeba hydroxena 


Reynolds and Threlkeld 

Spirillina vivipara 

12 (diploid) 


Patellina corrugata 

24 (diploid) 


Pontigulasia vas 



Actinophrys sol 

44 (diploid) 


Oxnerella maritima 

About 24 


Thalassicolla nucleata 



Aulacantha scolymantha 

More than 1600 


4 in gamogony 


Zygosoma globosum 

12 (diploid) 


Diplocystis schneideri 

6 (diploid) 


Gregarina blattarum 

6 (diploid) 


Nina gracilis 

5 (haploid) 

L6ger and Duboscq 

Actinocephalus parvus 

8 (diploid) 


Aggregata eberthi 

12 (diploid) 

Dobell; Belaf; Naville 

Merocystis kathae 

6 (haploid) 


Adelea ovata 

8-10 (diploid) 


Adelina deronis 

20 (diploid) 


Orcheobius herpobdellae 



Chloromyxum leydigi 

4 (diploid) 


Sphaerospora polymorpha 

4 (diploid) 


Myxidium lieberkuhni 



M. serotinum 

4 (diploid) 


Sphaeromyxa sabrazesi 


Debaisieux; Belaf 



S. balbianii 



Myxobolus pfeifferi 


Keysselitz; Mercier; 

Protoopalina intestinalis 

8 (diploid) 


Zelleriella antilliensis 



Z. intermedia 



Didinium nasutum 

16 (diploid) 


Cyclotrichium meunieri 



Table 5. — Continued 


Number of 


Chilodonella uncinata 

4 (diploid) 

Enrique; MacDougall 

C. uncinata (tetraploid) 

8; 4 


Conchophthirus anodontae 

12 (diploid) 


C. mytili 

16 (diploid) 


Ancistruma isseli 

About 5 (haploid) 


Paramecium aurelia 



About 35 


P. caudatum 

About 36 


Stentor coeruleus 

28 (diploid) 


Tetrato.vum unifasciculatum 

About 14 


Oxytricha bifaria 

24 (diploid) 


0. fallax 

24 (diploid) 


Uroleptus halseyi 

24 (diploid) 


Pleurotricha lanceolata 

About 40 (dipl.) 


Stylonychia pustulata 



Eaplotes patella 

6 (diploid) 

Yocom; Ivanic 

E. eurystomus 

8 (diploid) 


Vorticella microstoma 



Carchesium polypinum 

16 (diploid) 


Trichodina sp. 



vision, giving rise to daughter blepharoplasts and kinetosomes that 
become organized into characteristic locomotor organelles. Morpho- 
genesis in the apostomes (Chatton and Lwoff, 1935; Lwoff, 1950); 
mechanism of morphogenesis in ciliates (Faure-Fremiet, 1948; Guil- 
cher, 1950; Weisz, 1951, 1951a). 

Binary fission. As in metazoan cells, the binary fission occurs very 
widely among the Protozoa. It is a division of the body through 
middle of the extended long axis into two nearly equal daughter 
individuals. In Amoeba proteus, Chalkley and Daniel found that 
there is a definite correlation between the stages of nuclear divi- 
sion and external morphological changes (Fig. 68). During the pro- 
phase, the organism is rounded, studded with fine pseudopodia and 
exhibits under reflected light a clearly defined hyaline area near its 
center (a), which disappears in the metaphase (b, c). During the 
anaphase the pseudopodia rapidly become coarser; in the telophase 
the elongation of body, cleft formation, and return to normal 
pseudopodia, take place. 

In Testacea, one of the daughter individuals remains, as a rule, 
within the old test, while the other moves into a newly formed one, 



as in Arcella, Pyxidicula, Euglypha, etc. According to Doflein, the 
division plane coincides with the axis of body in Cochliopodium, 
Pseudodifflugia, etc., and the delicate homogeneous test also divides 
into two parts. In the majority of the Mastigophora, the division is 
longitudinal, as is shown by that of Rhabdomonas incurva (Fig. 69). 
In certain dinoflagellates, such as Ceratium, Cochliodinium, etc., 
the division plane is oblique, while in forms such as Oxyrrhis (Dunk- 

b ^ 


Fig. 68. External morphological changes during division of Amoeba 
proteus, as viewed in life in reflected light, X about 20 (Chalkley and 
Daniel), a, shortly before the formation of the division sphere; b, a later 
stage; c, prior to elongation; d, further elongation; e, division almost 

erly; Hall), the fission is transverse. In Streblomastix strix (Kofoid 
and Swezy, 1919), Lophomonas striata (Kudo, 1926b), Spirotricho- 
nympha bispira (Cleveland, 1938), Holomastigotoides tusitala (Fig. 
64) and others (Cleveland, 1947), and Strombidium clavellinae (Bud- 
denbrock, 1922), the division takes place transversely but the polar- 
ity of the posterior individual is reversed so that the posterior end 
of the parent organism becomes the anterior end of the posterior 
daughter individual. In the ciliate Bursaria, Lund (1917), observed 
reversal of polarity in one of the daughter organisms at the time of 
division of normal individuals and also in those which regenerated 
after being cut into one-half the normal size. 



In the Ciliophora the division is as a rule transverse (Fig. 52), in 
which the body without any enlargement or elongation divides by 
constriction through the middle so that the two daughter indivi- 
duals are about half as large at the end of division. Both individuals 
usually retain their polarity. 

Multiple division. In multiple division the body divides into a 
number of daughter individuals, with or without residual cyto- 

Fig. 69. Nuclear and cytoplasmic division in Rhabdomonas incurva, 
X about 1400 (Hall), a, resting stage; b, c, prophase; d, equatorial plate; 
e, f, anaphase; g, telophase. 

plasmic masses of the parent body. In this process the nucleus 
may undergo either simultaneous multiple division, as in Aggregata, 
or more commonly, repeated binary fission, as in Plasmodium (Fig. 
256) to produce large numbers of nuclei, each of which becomes the 
center of a new individual. The number of daughter individuals often 
varies, not only among the different species, but also within one and 
the same species. Multiple division occurs commonly in the Fora- 
minifera (Fig. 208); the Radiolaria (Fig. 218), and various groups of 
Sporozoa in which the trophozoite multiplies abundantly by this 

Budding. Multiplication by budding which occurs in the Proto- 
zoa is the formation of one or more smaller individuals from the 



parent organism. It is either exogenous or endogenous, depending 
upon the location of the developing buds or gemmules. Exogenous 
budding has been reported in Acanthocystis, Noctiluca (Fig. 127), 
Myxosporidia (Fig. 70, b), astomatous ciliates (Fig. 298), Chono- 
tricha, Suctoria (Fig. 371, k), etc. Endogenous budding has been 



Fig. 70. a, b, budding in Myxidium lieberkiihni; c, d, plasmotomy in 
Chloromyxum leydigi; e, plasmotomy in Sphaeromyxa balbianii. 

found in Testacea, Gregarinida, Myxosporidia (Figs. 279, e; 281, j), 
and other Sporozoa as well as Suctoria (Fig. 371, h). Collin observed 
a unique budding in Tokophrya cyclopum in which the entire body, 
excepting the stalk and pellicle, transforms itself into a young 
ciliated bud and leaves sooner or later the parent pellicle. 

Plasmotomy. Occasionally the multinucleate body of a protozoan 
divides into two or more small, mutinucleate individuals, the cyto- 
plasmic division taking place independently of nuclear division. This 
has been called plasmotomy by Doflein. It has been observed in the 



trophozoites of several coelozoic myxosporidians, such as Chloro- 
■myxumleydigi, Sphaeromyxa balbianii (Fig. 70), etc. It occurs further 
in certain Sarcodina such as Mycetozoa (Fig. 179) and Pelomyxa 
(Fig. 71), and Protociliata. 

Fig. 71. Eight individuals of Pelomyxa carolinensis, seen undisturbed 
in culture dishes, in which mitotic stages occurred as follows, X40 (Kudo) : 
a, early prophase; b, c, later prophase; d, metaphase; e, f, early and late 
anaphase; g, h, late telophase to resting nuclei (g, plasmotomy into two 
individuals; h, plasmotomy into three daughters). 

Colony formation 

When the division is repeated without a complete separation of 
the daughter individuals, a colonial form is produced. The compon- 


ent individuals of a colony may either have protoplasmic connections 
among them or be grouped within a gelatinous envelope if completely 
separated. Or, in the case of loricate or stalked forms, these exo- 
skeletal structures may become attached to one another. Although 
varied in appearance, the arrangement and relationship of the com- 
ponent individuals are constant, and this makes the basis for dis- 
tinguishing the types of protozoan colonies, as follows: 

Catenoid or linear colony. The daughter individuals are attached 
endwise, forming a chain of several individuals. It is of compara- 
tively uncommon occurrence. Examples: Astomatous ciliates such as 
Radiophrya (Fig. 298), Protoradiophrya (Fig. 298) and dinoflagel- 
lates such as Ceratium, Haplozoon (Fig. 130) and Polykrikos (Fig. 

Arboroid or dendritic colony. The individuals remain connected 
with one another in a tree-form. The attachment may be by means 
of the lorica, stalk, or gelatinous secretions. It is a very common 
colony found in different groups. Examples: Dinobryon (Fig. 108), 
Hyalobryon (Fig. 108), etc. (connection by lorica); Colacium (Fig. 
121), many Peritricha (Figs. 362; 364), etc. (by stalk); Poterioden- 
dron (Fig. 139), Stylobryon (Fig. 151), etc. (by lorica and stalk); 
Hydrurus (Fig. 109), Spongomonas (Fig. 150), Cladomonas(Fig. 150) 
and Anthophysis (Fig. 151) (by gelatinous secretions). 

Discoid colony. A small number of individuals are arranged in a 
single plane and grouped together by a gelatinous substance. Exam- 
ples: Cyclonexis (Fig. 108), Gonium (Fig. 116), Platydorina (Fig. 
117), Protospongia (Fig. 138), Bicosoeca (Fig. 139), etc. 

Spheroid colony. The individuals are grouped in a spherical form. 
Usually enveloped by a distinct gelatinous mass, the component 
individuals may possess protoplasmic connections among them. 
Examples: Uroglena (Fig. 108, c), Uroglenopsis (Fig. 108, d), Volvox 
(Fig. 115), Pandorina (Fig. 117,/), Eudorina (Fig. 117, h), etc. Such 
forms as Stephanoon (Fig. 117, a) appear to be intermediate between 
this and the discoid type. The component cells of some spheroid 
colonies show a distinct differentiation into somatic and reproductive 
individuals, the latter developing from certain somatic cells during 
the course of development. 

The gregaloid colony, which is sometimes spoken of, is a loose 
group of individuals of one species, usually of Sarcodina, which 
become attached to one another by means of pseudopodia in an ir- 
regular form. 



Asexual reproduction 

The Protozoa nourish themselves by certain methods, grow and 
multiply, by the methods described in the preceding pages. This 
phase of the life-cycle of a protozoan is the vegetative stage or the 
trophozoite. The trophozoite repeats its asexual reproduction process 
under favorable circumstances. Generally speaking, the Sporozoa 
ncrease to a much greater number by multiple division or schizog- 
ony and the trophozoites are called schizonts. 

Under certain conditions, the trophozoite undergoes encystment 
(Fig. 72). Prior to encystment, the trophozoites cease to ingest, and 
extrude remains of, food particles, resulting in somewhat smaller 
forms which are usually rounded and less active. This phase is some- 

Fig. 72. Encystment of Lophomonas blattarum, X1150 (Kudo). 

times called the precystic stage. The whole organism becomes de- 
differentiated; namely, various cell organs such as cilia, cirri, 
flagella, axostyle, peristome, etc., become usually absorbed. Finally 
the organism secretes substances which become solidified into a re- 
sistant wall, and thus the cyst is formed. In this condition, the 
protozoan is apparently able to maintain its vitality for a certain 
length of time under unfavorable conditions. 

Protozoa appear to encyst under various conditions. Low tem- 
perature (Schmahl, 1926), evaporation (Belaf, 1921; Bodine, 1923; 
Garnjobst, 1928), change in pH (Koffman, 1924; Darby, 1929), low 
or high oxygen content (Brand, 1923; Rosenberg, 1938), accumula- 
tion of metabolic products (Belaf, 1921; Mast and Ibara, 1923; 
Beers, 1926) or of associated bacteria (Mouton, 1902; Belaf, 1921) 
and over-population (Barker and Taylor, 1931) in the water in which 
Protozoa live, have been reported to bring about encystment. While 


lack of food in the culture has been noted by many observers 
(Oehler, 1916; Claff, Dewey and Kidder, 1941; Singh, 1941; Beers, 
1948; etc.) as a cause of encystment in a number of Protozoa such 
as Blepharisma (Stolte, 1922), Polytomella (Kater and Burroughs, 
1926), Didinium (Mast and Ibara, 1931), Uroleptus (Calkins, 1933), 
etc., an abundance of food and adequate nourishment seem to be 
prerequisite for encystment. Particular food was found in some in- 
stances to induce encystment. For example, Singh (1948) employed 
for culture of Leptomyxa reticulata, 40 strains of bacteria, of which 
15 led to the production of a large number of cysts in this sarcodinan. 
Encystment of Entamoeba histolytica is easily obtained by adding 
starch to the culture (Dobell and Laidlow, 1926; Balamuth, 1951). 

The age of culture, if kept under favorable conditions, does not 
influence encystment. Didinium after 750 generations, according to 
Beers (1927), showed practically the same encystment rate as those 
which had passed through 10 or 20 generations since the last encyst- 
ment. When Leptomyxa mentioned above is cultured for more than 
a year, no encystment occurred, but young cultures when supplied 
with certain bacteria encysted (Singh, 1948). 

In some cases, the organisms encyst temporarily in order to un- 
dergo nuclear reorganization and multiplication as in Colpoda (Fig. 
73) (Kidder and Claff, 1938; Stuart, Kidder and Griffin, 1939), Til- 
lina (Beers, 1946), etc. In Ichthyophthirius, the organism encysts 
after leaving the host fish and upon coming in contact with a solid 
object, and multiplies into numerous "ciliospores" (MacLennan, 
1937). Pelomyxa carolinensis (Illinois stock) has not encysted since 
its discovery in 1944, although the cultures were subjected to vari- 
ous environmental changes, but P. illinoisensis has been found to 
encyst and excyst frequently in flourishing cultures (Kudo, 1951). 
Thus it may be assumed that some unknown internal factors play 
as great a part as do the external factors in the phenomenon of en- 
cystment (Ivanic, 1934; Cutler and Crump, 1935). 

The cyst is covered by one to three membranes. Though generally 
homogeneous, the wall of cyst may contain siliceous scales as in 
Euglypha (Fig. 74). While chitinous substance is the common ma- 
terial of which the cyst wall is composed, cellulose makes up the 
cyst membrane of many Phytomastigina. Entz (1925) found the 
cysts of various species of Ceratium less variable in size as com- 
pared with the vegetative form, and found in all, glycogen, oil and 

The capacity of Protozoa to produce cyst is probably one of the 



reasons why they are so widely distributed over the surface of the 
globe. The minute protozoan cysts are easily carried from place to 
place by wind, attached to soil particles, debris, etc., by the flowing 
water of rivers or the current in oceans or by insects, birds, other 

Fig. 73. Diagram showing the life cycle of Colpoda cucullus (Kidder and 
Claff). a-j, normal reproductive activity repeated (j-b) under favorable 
cultural conditions; k-o, resistant cyst (k-n, nuclear reorganization and 
chromatin elimination). 

animals to which they become readily attached. The cyst is capable 
of remaining viable for a long period of time : eight years in Haema- 
tococcus pluvialis (Reichenow, 1929), four yaers in Spathidium spath- 
ula and Oxytricha sp. (Dawson and Mitchell, 1929), five years in 
Colpoda cucullus (Dawson and Hewitt, 1931), 10 years in Didinium 
nasutum (Beers, 1937), etc. 



When a cyst encounters a proper environment, redifferentiation 
takes place within the cyst. Various organellae which characterize 
the organism, are regenerated and reformed, and the young tropho- 
zoite excysts. The emerged organism returns once more to its trophic 
phase of existence. Experimental data indicate that excystment 
takes place under conditions such as addition of fresh culture me- 
dium (Kiihn, 1915; Rosenberg, 1938), hypertonic solution (Ilowai- 
sky, 1926), distilled water (Johnson and Evans, 1941), organic in- 
fusion (Mast, 1917; Beers, 1926; Barker and Taylor, 1933), and bac- 
terial infusion (Singh, 1941; Beers, 1946a) to the culture medium. 
Change in pH (Koffman, 1924), lowering the temperature (John- 
son and Evans, 1941) and increase in oxygen content (Brand, 1923; 
Finley, 1936) of the medium have also been reported as bringing 
about excystment. Excystment in Colpoda cucullus is said to be due 

Fig. 74. Encystment of Euglypha acanthophora, X320 (Kiihn). 

to specific inducing substances present in plant infusion (Thimann 
and Barker, 1934; Haagen-Smit and Thimann, 1938). Experiment- 
ing with two soil amoebae, "species 4 and Z," Crump (1950) found 
that the excystment in species Z took place without the presence of 
bacteria and regardless of the age of the cysts, but species 4 excysted 
only in the presence of certain bacteria (Aerobacter sp. or "4036") 
and the excystment diminished with the age of cysts. Crump sug- 
gested that the two strains of bacteria appeared to produce some 
material which induced excystment in Amoeba species 4. In Tillina 
magna, Beers (1945) found, however, the primary excystment-in- 
ducing factor to be of an osmotic nature and inducing substances, 
a secondary one. 

As to how an aperture or apertures are formed in the cyst wall 
prior to the emergence of the content, precise information is not 
yet on hand, though there are many observations. In the excyst- 
ment in Didinium and Tillina, Beers (1935, 1945, 1945a) notes that 



an increased internal pressure due to the imbibition of water, re- 
sults in the rupture of the cyst wall which had lost its rigidity and 
resistance (Fig. 75). Apertures in the cyst wall of Pelomyxa illi- 
noisensis are apparently produced by pseudopodial pressure (Kudo, 
1951). Seeing a similar aperture formation in the cyst of Entamoeba 
histolytica, Dobell (1928) "imagined that the amoeba secretes a fer- 
ment which dissolves the cyst wall." 

Fig. 75. Excystment in Didinium nasutum, as seen in a single indi- 
vidual, X250 (Beers), a, resting cyst; b, appearance of "excystment" 
vacuole; c, rupture of the cyst membrane, the vacuole is becoming en- 
larged; d, e, emergence of the cyst content, the vacuole increasing in 
size; f, the empty outer cyst membrane; g, the free organism with the 
inner membrane; h, organism after discharge of vacuole; i, j, later stages 
of emergence of the ciliate. 

Although encystment seems to be an essential phase in the life 
cycle of Protozoa in general, there are certain Protozoa including 
such common and widely distributed forms as the species of Para- 
mecium in which this phenomenon has not been definitely observed 
(p. 744). In some Sporozoa, encystment is followed by production 
of large numbers of spores, while in others there is no encystment. 
Here at the end of active multiplication of trophozoite, sexual re- 



production usually initiates the production of the spores (Fig. 76). 
The spores which are protected by a resistant membrane are capa- 
ble of remaining viable for a long period of time outside the host 

Fig. 76. Diagram illustrating the life-cycle of Thelohania legeri (Kudo), 
a, extrusion of the polar filament in gut of anopheline larva; b, emerged 
amoebula; c-f, schizogony in fat body; g-m, sporont-formation; m-x, 
stages in spore-formation. 

Sexual reproduction and life-cycles 

Besides reproducing by the asexual method, numerous Protozoa 
reproduce themselves in a manner comparable with the sexual re- 
production which occurs universally in the Metazoa. Various types 
of sexual reproduction have been reported in literature, of which a 
few will be considered here. The sexual fusion or syngamy which is a 
complete union of two gametes, has been reported from various 
groups, while the conjugation which is a temporary union of two 
individuals for the purpose of exchanging the nuclear material, is 
found almost exclusively in the Ciliophora. 

Sexual fusion. The gametes which develop from trophozoites, may 
be morphologically alike (isogametes) or unlike (anisogametes) , 


both of which are, in well-studied forms, physiologically different 
as judged by their behavior toward each other. If a gamete does not 
meet with another one, it perishes. Anisogametes are called micro- 
gametes and macrogametes. Difference between them is comparable 
in many instances (Figs. 77, 256) with that which exists between the 
spermatozoa and the ova of Metazoa. The microgametes are motile, 
relatively small and usually numerous, while the macrogametes are 
usually not motile, much more voluminous and fewer in number. 
Therefore, they have sometimes been referred to as male and female 
gametes (Fig. 77). 


Fig. 77. a, macrogamete, and b, microgamete of Volvox aureus, 
X1000 (Klein). 

While morphological differences between the gametes have long 
been known and studied by many workers, whatever information 
we possess on physiological differences between them is of recent 
origin. Since 1933, Moewus and his co-workers have published a 
series of papers based upon their extended studies of bacteria-free 
cultures of many species (and strains) of Chlamydomonas (p. 276) 
which throw some light on the gamete differentiation among these 
phytomonadinans. The gametes in Chlamydomonas are mostly 
isogamous, except in a few forms. Sexual fusion takes place in the 
majority of species and strains between the gametes produced in 
different clones, and there is no gametic fusion within a single clone. 
Moewus obtained "sex substances" from some of the cultures and 
showed that these are chemotactic substances. Each gamete secretes 
substances that attract the other and each reacts to the substances 
secreted by the other. Kiihn, Moewus and Wendt (1939) recognized 
"hormones," and named them, termones (sex-determining hor- 
mones), anderotermone (male-determining hormone) and gynoter- 
mone (female-determining hormone). 

In a few strains or species of Chlamydomonas, sexual fusion is 
found to take place among the gametes that develop within a single 
clone. Moewus considers in these cases there exist two types of 
gametes in a clone. However, Pascher, Pringsheim, and others ob- 



Fig. 78. Sexual fusion in Copromonas subtilis, X1300 (Dobell). 

tained results which seem to indicate that there is no physiological 
or sex differentiation between the fusing gametes. In the much- 
studied Sporozoa, for example, Plasmodium, the two gametes are 
both morphologically and physiologically differentiated, and sexual 
fusion always takes place between two anisogametes. 

Fig. 79. Sexual fusion in Trinema linearis, X960 (Dunkerly). a, an 
organism in life, with the resting nucleus and two contractile vacuoles; 
b, union of two individuals; c, fusion of the organisms in one test, sur- 
rounded by cyst membrane; d, older cyst; e, still older cyst with a single 



The isogamy is typically represented by the flagellate Copro- 
monas subtilis (Fig. 78), in which there occurs, according to Dobell, 

Fig. 80. The life-cycle of Stephanosphaera pluvialis (Hieronymus). 
a-e, asexual reproduction; f-m, sexual reproduction. 

a complete nuclear and cytoplasmic fusion between two isogametes. 
Each nucleus, after casting off a portion of its nuclear material, 
fuses with the other, thus forming a zygote containing a synkaryon. 
In Trinerna lineare (Fig. 79), Dunkerly (1923) saw isogamy in which 

Fig. 81. Sexual reproduction in Trichonympha of Cryptocercus 
(Cleveland), a, vegetative individual; b, gametocyte in early stage of 
encystment; c, anterior end of the same organism (chromosomes have 
been duplicated, nuclear sleeve is opening at seams and granules are 
flowing into the cytoplasm); d, further separation of the male and fe- 
male chromosomes; e, the nuclear division has been completed, few old 
flagella remain and new post rostral flagella are growing; f, the cytoplas- 
mic division has begun at the anterior end; g, the gametes just before ex- 
cystment, the female showing the developing ring of fertilization granules; 
h, a female gamete; i, a female gamete with a fertilization ring, a, X350; 
b, X320; c, X600; d-i, X280. 


two individuals undergo a complete fusion within one test and en- 
cyst. In Stephanosphaera pluvialis (Fig. 80), both asexual and sexual 
reproductions occur, according to Hieronymus. Each individual 
multiplies and develops into numerous biflagellate gametes, all of 
which are alike. Isogamy between two gametes results in formation 
of numerous zygotes which later develop into trophozoites. 

Anisogamy has been observed in certain Foraminifera. It perhaps 
occurs in the Radiolaria also, although positive evidence has yet to 
be presented. Anisogamy seems to be more widely distributed. In 
Pandorina morum, Pringsheim observed that each cell develops asex- 
ually into a young colony or into anisogametes which undergo sexual 
fusion and encyst. The organism emerges from the cyst and develops 
into a young trophozoite. A similar life-cycle was found by Goebel in 
Eudorina elegc.ns 

The wood-roach inhabiting flagellates belonging to Trichonympha, 
Oxymonas, Saccinobaculus, Notila and Eucomonympha, were found 
by Cleveland (1949a-1951a) to undergo sexual reproduction when 
the host insect molts. It has been observed that the gamete-forma- 
tion is induced by the molting hormone produced by the prothoracic 
glands of the host insect. The sexual reproduction of Trichonympha, 
possessing 24 chromosomes, as observed and described by Cleve- 
land, is briefly as follows (Figs. 81, 82): About three days before its 
host molts, the haploid nucleus in the flagellate divides, in which 
two types of daughter chromosomes (or chromatids) become sepa- 
rated from each other: the dark-staining male gamete nucleus and 
light-staining female gamete nucleus (Fig. 81, b-d); in the mean- 
time, a membrane is formed to envelop the organism (b, d). When 
the cytoplasmic division is completed (e-g), the two gametes "ex- 
cyst" and become free in the host gut (h; Fig. 82, b). In the female 
gamete, there appear "fertilization granules" (Fig. 81, h), which 
gather at the posterior extremity (i), through which a fluid-filled 
vesicle ("fertilization cone") protrudes (Fig. 82, a). A male gamete 
(6) comes in touch with a female gamete only at this point (c), and 
enters the latter (d-f). The two gamete nuclei fuse into a diploid 
synkaryon (g, h). The zygote and its nucleus begin immediately to 
increase in size, and undergo two meiotic divisions (i-k), finally giv- 
ing rise to vegetative individuals (Fig. 81, a). 

Among the Sporozoa, anisogamy is of common occurrence. In 
Coccidia, the process was well studied in Eimeria schubergi (Fig. 
243), Aggregata eberthi (Fig. 246), Adelea ovata (Fig. 253), etc., and 
the resulting products are the oocysts (zygotes) in which the spores 
or sporozoites develop. Similarly in Haemosporidia such as Plasmo- 



Fig. 82. Sexual reproduction in Trichonympha of Cryptocercus 
(Cleveland), a, a female gamete with a fetilization ring and cone; b, a 
male gamete; c-g, stages in fusion and fertilization; h, a zygote; i, telo- 
phase of the first meiotic division of the zygote nucleus; j, k, prophase and 
anaphase of the second meiotic division, a-g, X280;h, X215;i-k, X600. 


dium vivax (Fig. 256), anisogamy results in the formation of the 
ookinetes or motile zygotes which give rise to a large number of 
sporozoites. Among Myxosporidia, a complete information as to 
how the initiation of sporogony is associated with sexual reproduc- 
tion, is still lacking. Naville, however, states that in the trophozoite 
of Sphaeromyxa sabrazesi (Fig. 277), micro- and macro-gametes 
develop, each with a haploid nucleus. Anisogamy, however, is pe- 
culiar in that the two nuclei remain independent. The microgametic 
nucleus divides once and the two nuclei remain as the vegetative 
nuclei of the pansporoblast, while the macrogamete nucleus multi- 
plies repeatedly and develop into two spores. Anisogamy has been 
suggested to occur in some members of Amoebina, particularly in 
Endamoeba blattae (Mercier, 1909). Cultural studies of various para- 
sitic amoebae in recent years show, however, no evidence of sexual 
reproduction. Among the Ciliophora, the sexual fusion occurs only 
in Protociliata (Fig. 294). 

Conjugation. The conjugation is a temporary union of two indivi- 
duals of one and the same species for the purpose of exchanging part 
of the nuclear material and occurs almost exclusively in the Euci- 
liata and Suctoria. The two individuals which participate in this 
process may be either isogamous or anisogamous. In Paramecium 
caudatum (Fig. 83), the process of conjugation has been studied by 
many workers, including Biitschli (1876), Maupas (1889), Calkins 
and Cull (1907), and others. Briefly the process is as follows: Two 
similar individuals come in contact on their oral surface (a). The 
micronucleus in each conjugant divides twice (b-e), forming four 
micronuclei, three of which degenerate and do not take active part 
during further changes (f-h). The remaining micronucleus divides 
once more, producing a wandering pronucleus and a stationary pro- 
nucleus (/, g). The wandering pronucleus in each of the conjugants 
enters the other individual and fuses with its stationary pronucleus 
(h, r). The two conjugants now separate from each other and be- 
come exconjugants. In each exconjugant, the synkaryon divides 
three times in succession (i-m) and produces eight nuclei (n), four 
of which remain as micronuclei, while the other four develop into 
new macronuclei (o). Cytoplasmic fision follows then, producing 
first, two individuals with four nuclei (p) and then, four small in- 
dividuals, each containing a micronucleus and a macronucleus (a). 
Jennings maintained that of the four smaller nuclei formed in the 
exconjugant (o), only one remains active and the other three de- 
generate. This active nucleus divides prior to the cytoplasmic divi- 



Fig. 83. Diagram illustrating the conjugation of Paramecium caudatum. 
a-q, X about 130 (Calkins); r, a synkaryon formation as in h, X1200 


sion so that in the next stage (p), there are two developing macro- 
nuclei and one micronucleus which divides once more before the 
second and last cytoplasmic division (q). During these changes, the 
original macronucleus disintegrates, degenerates, and finally be- 
comes absorbed in the cytoplasm. 

Although this is the general course of events in the conjugation 
of this ciliate, recent observations revealed a number of different 
nuclear behavior. For example, there may not be pronuclear ex- 
change between the conjugants (cytogamy, p. 204), thus resulting 
in self fertilization (Diller, 1950a). In a number of races, Diller 
(1950) found that one of the two nuclei produced by the first divi- 
sion of the synkaryon degenerates, while the other nucleus divides 
three times, forming 8 nuclei, and furthermore, an exconjugant may 
conjugate occasionally with another individual before the reorgani- 
zation has been completed. 

The conjugaton of P. bursaria has also received attention of 
many workers. According to Chen (1946a), the first micronuclear 
division is a long process. One daughter nucleus degenerates and 
the other undergoes a second division. Here again one nucleus de- 
generates, while the other divides once more, giving rise to a wan- 
dering and a stationary pronucleus. Exchange of the wandering 
pronuclei is followed by the fusion of the two pronuclei in each 
conjugant. The synkaryon then divides. One of the two nuclei 
formed by this division degenerates, while the other gives rise to 
four nuclei by two divisions. The latter presently become dif- 
ferentiated into two micronuclei and two macronuclei, followed 
by a cytoplasmic division. The time two conjugants remain paired 
is said to be 20-38 or more hours (Chen, 1946c). In this Paramecium 
also, various nuclear activities have been reported. Chen (1940a, c) 
found that conjugation between a micronucleate and an amicronu- 
cleate can sometimes occur. In such a case, the micronucleus in the 
normal individual divides three times, and one of the pronuclei mi- 
grates into the amicronucleate in which there is naturally no nu- 
clear division. The single haploid nucleus ("hemicaryon") in each 
individual divides three times as mentioned above and four nuclei 
are produced. Thus amicronucleate becomes micronucleated. Con- 
jugating pairs sometimes separate from each other in a few hours. 
Chen (1946c) found that when such pairs are kept in a depression 
slide, temporary pairing recurs daily for many days, though there 
is seemingly no nuclear change. Chen (1940) further observed that 
the micronucleus in this species is subject to variation in size and 


in the quantity of chromatin it contains, which gives rise to dif- 
ferent (about 80 to several hundred) chromosome numbers during 
conjugation in different races, and that polyploidy is not uncom- 
mon in this ciliate. This investigator considers that polyploidy is 
a result of fusion of more than two pronuclei which he observed on 
several occasions. The increased number of pronuclei in a conju- 
gant may be due to: (1) the failure of one of the two nuclei produced 
by the first or second division to degenerate; (2) the conjugation 
between a unimicronucleate and a bimicronucleate, or (3) the fail- 
ure of the wandering pronucleus to enter the other conjugant; with 
this latter view Wichterman (1946) agrees. Apparently polyploidy 
occurs in other species also; for example, in P. caudatum (Calkins 
and Cull, 1907; Penn, 1937). 

In P. trichium, Diller (1948) reported that the usual process of 
conjugation is the sequence of three micronuclear divisions, pro- 
ducing the pronuclei (during which degeneration of nuclei may oc- 
cur at the end of both the first and second divisions), cross- or 
self-fertilization and three divisions of the synkarya. Ordinarily four 
of the eight nuclei become macronuclei, one remains as the micro- 
nucleus and the other three degenerate. The micronucleus divides 
at each of the two cytoplasmic divisions. Exchange of strands of the 
macronuclear skein may take place between the conjugants. Diller 
found a number of variations such as omission of the third prefer- 
tilization division, autogamous development, etc., and remarked 
that heteroploidy is pronounced and common. 

In P. aurelia possessing typically two micronuclei, the process of 
conjugation was studied by Maupas (1889), Hertwig (1889), Dil- 
ler (1936), Sonneborn (1947), etc., and is as follows: Soon after bi- 
association begins, the two micronuclei in each conjugant divide 
twice and produce eight nuclei, seven of which degenerate, while the 
remaining one divides into two gametic nuclei (Maupas, Woodruff, 
Sonneborn) Diller notes that two or more of the eight nuclei divide 
for the third time, but all but two degenerate; the two gametic nu- 
clei may or may not be sister nuclei. All agree that there are two 
functional pronuclei in each conjugant. As in other species of Para- 
mecium already noted, there is a nuclear exchange which results in 
the formation of a synkaryon in each conjugant. The synkaryon di- 
vides twice and the conjugants separate from each other at about 
this time. Two nuclei develop into macronuclei and the other two 
into micronuclei. Prior to the first cytoplasmic division of the excon- 
jugant, the micronuclei divide once, but the macronucleus does not 
divide, so that each of the two daughters receives one macronucleus 


and two micronuclei. The original macronucleus in the conjugant 
becomes transformed into a skein which breaks up into 20 to 40 
small masses. These are resorbed in the cytoplasm as in other species. 
As to when these nuclear fragments are absorbed, depends upon the 
nutritive condition of the organism (Sonneborn); namely, under a 
poor nutritional condition the resorption begins and is completed 
early, but under a better condition this resorption takes place after 
several divisions. 

During conjugation reciprocal migration of a pronucleus thus oc- 
curs in all cases. During biassociation and even in autogamy (p. 203), 
there develops a conical elevation ("paroral cone") and the nuclear 
migration takes place through this region. Although there is ordi- 
narily no cytoplasmic exchange between the conjugants, this may 
occur in some cases as observed by Sonneborn (1943a, 1944). P. 
aurelia of variety 4, according to Sonneborn, do occasionally not 
separate after fertilization, but remain united by a thin strand in the 
region of the paroral cones. In some pairs, the strand enlarges into a 
broad band through which cytoplasm flows from one individual to 
the other. The first division gives off a normal single animal from 
each of the "parabiotic twins" and the two clones derived from the 
two individuals belong to the same mating type (p. 192). 

Conjugation between different species of Paramecium has been 
attempted by several workers. Muller (1932) succeeded in producing 
a few pairings between normal P. caudatum and exconjugant P. 
multimicronucleatum. The nuclear process ran normally in cauda- 
tum, which led Muller to believe that crossing might be possible, but 
without success. De Garis (1935) mixed "double animals" (p. 228) of 
P. caudatum and conjugating population of P. aurelia. Pairing be- 
tween them occurred readily, in which the aurelia mates remained 
attached to caudatum for five to 12 hours. Four pairs remained to- 
gether, but aurelia underwent cytolysis on the second day. The 
separated aurelia from other pairs died after showing "cloudy swell- 
ing" on the second or third day after biassociation. The caudatum 
double-animals on the other hand lived for two to 12 (average six) 
days during which there was neither growth nor division and finally 
perished after "hyaline degeneration." No information on nuclear 
behavior in these animals is available. Apparently, the different spe- 
cies of Paramecium are incompatible with one another. 

In 1937, Sonneborn discovered that in certain races of P. aurelia, 
there are two classes of individuals with respect to "sexual" differ- 
entiation and that the members of different classes conjugate with 
each other, while the members of each class do not. The members of 


a class or caryonide (Sonneborn, 1939) are progeny of one of the two 
individuals formed by the first division of an exconjugant and thus 
possess the same macronuclear constitution. These classes were des- 
ignated by Sonneborn (1938) as mating types. Soon a similar phe- 
nomenon was found by several workers in other species of Para- 

A ' ,r ,- , .- • 

*~K * * 







it _• ' . im. o _ • _i .*_, J 

Fig. 84. Mating behavior of Paramecium bursaria (Jennings), a, indi- 
viduals of a single mating type; b, 6 minutes after individuals of two mat- 
ing types have been mixed; c, after about 5 hours, the large masses have 
been broken down into small masses; d, after 24 hours, paired conjugants. 

mecium; namely, P. bursaria (Jennings, 1938), P. caudatum (Gil- 
man, 1939; Hiwatashi, 1949-1951), P. trichium, P. calkinsi (Sonne- 
born, 1938) and P. multimicronucleatum (Giese, 1939). When organ- 
isms which belong to different mating types are brought together, 
they adhere to one another in large clumps ("agglutination") of 
numerous individuals (Fig. 84, b). After a few to several hours, the 


large masses break down into small masses (c) and still later, con- 
jugants appear in pairs (d). The only other ciliate in which mating 
types are definitely known to occur is Euplotes patella in which, ac- 
cording to Kimball (1939), there occurs no agglutination mating re- 

How widely mating types occur is not known at present. But as 
was pointed out by Jennings, the mating types may be of general oc- 
currence among ciliates; for example, Maupas (1889) observed that 
in Lionotus (Loxophyllum) fasciola, Leucophrys patula, Stylonychia 
pustulata, and Onychodromus grandis, conjugation took place be- 
tween the members of two clones of different origin, and not among 
the members of a single clone. Precise information on the occurrence 
of mating types among different ciliates depends on future research. 

In Paramecium aurelia, Sonneborn distinguishes seven varieties 
which possess the same morphological characteristics of the species, 
but which differ in addition to mating types, also in size, division 
rate, conditions of temperature and light under which mating reac- 
tion may occur, etc. (Sonneborn, 1947). There occurs ordinarily no 
conjugation between the clones of different varieties. Within each of 
six varieties, there are two mating types, while there is only one type 
in the seventh variety. Animals belonging to the same variety, but 
to different mating types, only conjugate when put together (Table G). 

Under optimum breeding conditions two mating types of the same 
variety give 95 per cent immediate agglutination and conjugation. 
But exceptions occur. Sonneborn and Dipell (1946) place the 7 va- 
rieties of aurelia under two groups: A (varieties 1, 3, 5 and 7) and B 
(varieties 2, 4 and 6) on the basis of their conjugational reactions. 
Mating types in group A do not conjugate with those of group B; no 
mating type of group B is known to conjugate with any type of other 
varieties in this group; but a number of combinations of mating 
types belonging to different varieties of group A conjugate with each 
other. For example, varieties 1 and 5 conjugate (namely, type I with 
type X and type II with type IX); however these interparietal mat- 
ing reactions are (1) always less intense than intra varietal reaction, 
(2) dependent upon the degree of reactivity of the culture, and (3) 
different from the intravarietal reaction with respect to the condi- 
tions for optimum reaction. Furthermore in most cases, the progeny 
of intervarietal matings are not viable. In the varieties of group A, 
the mating types appear to be of a more general sort. Therefore, 
Sonneborn (1947) designated even- and odd-numbered types as + 
and — respectively. 



Table 6. — Groups, varieties and mating types in Paramecium 
aurelia (Sonneborn) 

indicates that conjugation does not occur; numbers show the 

maximum percentage of conjugant-pairs formed; Inc. 

indicates incomplete mating reaction 




































3 Inc. 





1 Inc. 
















In P. bursaria, Jennings (1938, 1939) found three varieties. Va- 
rieties 1 and 3 contain 4 mating types each, while variety 2, eight 
mating types. Jennings and Opitz (1944) further found variety 4 
(Russian), composed of tw r o mating types and variety 5 under which 
several Russian clones were placed. Chen (1946a) added variety 6 
(originating in Europe) containing four mating types. Thus in this 
species of Paramecium, there are now six varieties, containing 23 
mating types (Table 7), and mating reaction occurs even among 
enucleate fragments of animals of different mating types of the same 
variety (Tartar and Chen, 1941). In Euplotes patella, Kimball (1939) 
observed six mating types which he designated as type I to type VI 
(Table 8). 

Though the members of a clone are of the same mating type and 
therefore do not conjugate, a clone may undergo at very long inter- 
vals (some 2000 culture days), "self -differentiation" into tw r o mating 
types which then conjugate (Jennings, 1941). Furthermore, Jennings 


Table 7. — Varieties and mating types in Paramecium bursaria 
(Jennings; Jennings and Opitz; Chen) 

+ indicates that conjugation occurs; — indicates that it does not 









A B C D 



O P Q 

R S 


U V W X 


- + + + 

- + + 

- + 




- + + + + + + + 

- + + + + + + 

- + + + + + 

- + + + + 

- + + + 

- + + 

- + 

+ - 

+ - 
+ - 
+ - 


+ + + 

- + + 

- + 





- + 







- + + + 

- + + 

- + 

and Opitz (1944) found that mating type R (variety 4) conjugated 
with E, K, L or M (variety 2), but all conjugants or exconjugants 
perished without multiplication. Chen (1946a) made a cytological 
study of them and observed that the nuclear changes which are 


8. — Mating types in 


patella (E 


Mating type 



































seemingly normal during the first 16 hours, become abnormal sud- 
denly after that time, and the micronuclei divide only once and there 
is no nuclear exchange. The death of conjugants or exconjugants is 
possibly due to physiological incompatibility between the varieties 
upon coming in contact or probably due to "something that diffuses 
from one conjugant to the other." 

Studies of mating types have revealed much information re- 
garding conjugation. Conjugation usually does not occur in well-fed 
or extremely starved animals, and appears to take place shortly 
after the depletion of food. Temperature also plays a role in con- 
jugation, as it takes place within a certain range of temperature 
which varies even in a single species among different varieties 
(Sonneborn). Light seems to have different effects on conjugation 
in different varieties of P. aurelia. The time between two conju- 
gations also varies in different species and varieties. In P. bursaria, 
Jennings found that in some races the second conjugation would 
not take place for many months after the first, while in others 
such an "immature" period may be only a few weeks. In P. aurelia, 
in some varieties there is no "immature" period, while in others there 
is 6 to 10 days' "immaturity." 

Very little is known about the physiological state of conjugants 
as compared with vegetative individuals. Several investigators ob- 
served that animals which participate in conjugation show much 
viscous body surface. Boell and Woodruff (1941) found that the 
mating individuals of Paramecium calkinsi show a lower respiratory 
rate than not-mating individuals. Neither is the mechanism of con- 
jugation understood at present. Kimball (1942) discovered in 
Euplotes patella, the fluid taken from cultures of animals of one type 
induces conjugation among the animals of other types (p. 235). Pre- 
sumably certain substances are secreted by the organisms and be- 
come diffused in the culture fluid. In Paramecium aurelia, Sonne- 
born (1943) found that of the four races of variety 4, race 51 was a 
"killer," while the other three races, "sensitive." Fluid in which the 
killer race grew, kills the individuals of the sensitive races. As has 
been mentioned already, P. bursaria designated as type T (variety 
5) (Table 7) conjugates with none. But Chen (1945) found that its 
culture fluid induces conjugation among a small number of the indi- 
viduals of one mating type of varieties 2, 3, 4 and 6, in which nuclear 
changes proceed as in normal conjugation. Furthermore, this fluid 
is capable of inducing autogamy in single animals. Other visible in- 
fluences of the fluid on organisms are sluggishness of movement and 
darker coloration and distortion of the body. 


Boell and Woodruff (1941) noticed that in P. calkinsi, living indi- 
viduals of one mating type will agglutinate with dead ones of the 
complementary mating type. A similar phenomenon was also ob- 
served by Metz (194(5, 1947, 1948) who employed various methods of 
killing the animals. The pairs composed of living and formaldehyde- 
killed animals, behave much like normal conjugating pairs; there is 
of course no cross-fertilization, but the living member of the pair 
undergoes autogamy. While the "mating type substances" can be 
destroyed by exposure to 52°C. for five minutes; by X-irradiation; 
by exposure of formaldehyde-killed reactive animals to specific anti- 
sera or to 100°C, etc., Metz demonstrated that animals may be 
killed by many reagents which do not destroy these substances. 
Furthermore, all mating activities disappear when the animals are 
thoroughly broken up, which suggests that Paramecium might re- 
lease some mating substance inhibitory agent. This agent was later 
found in this Paramecium (Metz and Butterfield, 1950). Metz (4948) 
points out that the mating reaction involves substances present on 
the surfaces of the cilia, and supposes that the interaction between 
two mating-type substances initiates a chain of reactions leading up 
to the process of conjugation and autogamy. Hiwatashi (1949a, 
1950) using four groups (each composed of two mating types) of P. 
caudatum, confirmed Metz's observation. Metz and Butterfield 
(1951) more recently report that non-proteolytic enzymes (lecithin- 
ase, hyaluronidase, lysozyme, ptyalin, ribonuclease) have no de- 
tectable effect on the mating reactivity of P. calkinsi; but proteo- 
lytic enzymes such as trypsin and chymotrypsin destroy the mating 
reactivity, and mating substance activity was not found in the digest 
of enzyme-treated organisms. The two observers believe that the 
mating reactivity is dependent upon protein integrity. 

When the ciliate possesses more than one micronucleus, the 
first division ordinarily occurs in all and the second may or may 
not take place in all, varying apparently even among individuals 
of the same species. This seems to be the case with the majority, al- 
though more than one micronucleus may divide for the third time to 
produce several pronuclei, for example, two in Euplotes patella, Sty- 
lonychia pustulata; two to three in Oxytricha fallax and two to four in 
Uroleptus mobilis. This third division is often characterized by long 
extended nuclear membrane stretched between the division prod- 

Ordinarily the individuals which undergo conjugation appear to 
be morphologically similar to those that are engaged in the trophic 
activity, but in some species, the organism divides just prior to 



Fig. 85. The life-cycle of Nyctotherus cordiformis in Hyla versicolor 
(Wichterman). a, a cyst; b, excystment in tadpole; c, d, division is 
repeated until host metamorphoses; e, smaller preconjugant; f-j, con- 
jugation; k, exconjugant; 1, amphinucleus divides into 2 nuclei, one micro- 
nucleus and the other passes through the "spireme ball" stage before 
developing into a macronucleus; k-n, exconjugants found nearly exclu- 
sively in recently transformed host; o, mature trophozoite; p-s, binary 
fission stages; t, precystic stage. 


conjugation. According to Wichterman (1936), conjugation in 
Nyctotherus cordiformis (Fig. 85) takes place only among those 
which live in the tadpoles undergoing metamorphosis (f-j). The 
conjugants are said to be much smaller than the ordinary tropho- 
zoites, because of the preconjugation fission (d-e). The micronuclear 
divisions are similar to those that have been described for Para- 
mecium caudatum and finally two pronuclei are formed in each con- 
jugant. Exchange and fusion of pronuclei follow. In each exconjug- 
ant, the synkaryon divides once to form the micronucleus and the 
macronuclear anlage (k-l) which develops into the "spireme ball" 
and finally into the macronucleus (m-o). 

A sexual process which is somewhat intermediate between the 
sexual fusion and conjugation, is noted in several instances. Ac- 
cording to Maupas' (1888) classical work on Vorticella nebulifera, the 
ordinary vegetative form divides twice, forming four small indi- 
viduals, which become detached from one another and swim about 
independently. Presently each becomes attached to one side of a 
stalked individual. In it, the micronucleus divides three times and 
produces eight nuclei, of which seven degenerate; and the remaining 
nucleus divides once more. In the stalked form the micronucleus di- 
vides twice, forming four nuclei, of which three degenerate, and the 
other dividing into two. During these changes the two conjugants 
fuse completely. The wandering nucleus of the smaller conjugant 
unites with the stationary nucleus of the larger conjugant, the other 
two pronuclei degenerating. The synkaryon divides several times 
to form a number of nuclei, from some of which macronuclei are 
differentiated and exconjugant undergoes multiplication. In Vorti- 
cella microstoma (Fig. 86), Finley (1943) notes that a vegetative indi- 
vidual undergoes unequal division except the micronucleus which 
divides equally (a), and forms a large stalked macroconjugant and a 
small free microconjugant (b). The conjugation which requires 18- 
24 hours for completion, begins when a microconjugant attaches it- 
self to the lower third of a macroconjugant. The protoplasm of the 
microconjugant enters the macroconjugant (c). The micronucleus of 
the microconjugant divides three times, the last one of which being 
reductional (d, e), while that of the macroconjugant divides twice 
(one mitotic and one meiotic). Fusion of one of each produces a 
synkaryon (/) which divides three times. One of the division products 
becomes a micronucleus and the other seven macronuclear anlagen 
(g, h) which are distributed among the progeny (i,j). 

Another example of this type has been observed in Metopus es 



(Fig. 87). According to No land (1927), the conjugants fuse along the 
anterior end (a), and the micronucleus in each individual divides in 
the same way as was observed in Paramecium caudatum ib-e). But 
the cytoplasm and both pronuclei of one conjugant pass into the 
other (J), leaving the degenerating macronucleus and a small 

Fig. 86. Sexual reproduction in Vorticella microstoma, X800 (Fin- 
ley), a, preconj ligation division which forms a macroconjugant ami a 
microconjugant; b, a macroconjugant with three microconjugants; c, a 
microconjugant fusing with a macroconjugant; d, the micronucleus of the 
microconjugant divided into four nuclei; e, with 12 nuclei formed by di- 
visions of the two micronuclei of conjugants; f, synkaryon; g, eight nu- 
clei after three divisions of synkaryon; h, seven enlarging macronuclear 
anlagen and a micronucleus in division; i, first division; j, a daughter in- 
dividual with a micronucleus, four macronuclear anlagen. and old macro- 
nuclear fragments. 



amount of cytoplasm behind in the shrunken pellicle of the smaller 
conjugant which then separates from the other (j). In the larger 
exconjugant, two pronuclei fuse, and the other two degenerate and 
disappear (g, h) . The synkaryon divides into two nuclei, one of which 
condenses into the micronucleus and the other grows into the macro- 
nucleus (i, k-m). This is followed by the loss of cilia and encystment. 
While ordinarily two individuals participate in conjugation, three 

Fig. 87. Conjugation of Metopus es (Noland). a, early stage; b, first 
micronuclear division; c, d, second micronuclear division; e, third micro- 
nuclear division; f, migration of pronuclei from one conjugant into the 
other; g, large conjugant with two pronuclei ready to fuse; h, large con- 
jugant with the synkaryon, degenerating pronuclei and macronucleus; 
i, large exconjugant with newlj r formed micronucleus and macronucleus 
j, small exconjugant with degenerating macronucleus; k-m, development 
of two nuclei, a, X290; b-j, X250, k-m, X590. 



or four individuals are occasionally involved. For example, conjuga- 
tion of three animals was observed in P. caudatum by Stein (1867), 
Jickeli (1884), Maupas (1889) and in Blepharisma vndulans by 
Giese (1938) and Weisz (1950). Chen (1940b, 1948) made a careful 
study of such a conjugaion which he found in Paramecium bur- 

Fig. 88. Conjugation of three individuals in Paramecium bursaria, 
X365 (Chen), a, late prophase of the first nuclear division (the individual 
on right is a member of a race with "several hundred chromosomes," 
while the other two belong to another race with "about 80 chromosomes") ; 
b, anaphase of the third division (each individual contains 2 degenerating 
nuclei); c, beginning of pronuclear exchange between two anterior ani- 
mals; d, e, synkaryon formation; f, after the first division of synkaryon, 
one daughter nucleus undergoing degeneration in all animals. 



saria (Fig. 88). He found that the usual manner of association is 
conjugation between a pair with the third conjugant attached to the 
posterior part of one of them (a). Nuclear changes occur in all three 
individuals, and in each, two pronuclei are formed by three divisions 
(c) . But the exchange of the pronuclei takes place only between two 
anterior conjugants (c-e) and autogamy (see below) occurs in the 
third individual. 

Fig. 89. Diagram illustrating autogamy in Paramecium aurelia (Diller). 
a, normal animal; b, first micronuclear division; c, second micronuclear 
division; d, individual with 8 micronuclei and macronucleus preparing for 
skein formation; e, two micronuclei dividing for the third time; f, two 
gamete-nuclei formed by the third division in the paroral cone; g, fusion 
of the nuclei, producing synkaryon; h, i, first and second division of 
synkaryon; j, with 4 nuclei, 2 becoming macronuclei and the other 2 re- 
maining as micronuclei; k, macronuclei developing, micronuclei dividing; 
1, one of the daughter individuals produced by fission. 

Automixis. In certain Protozoa, the fusion occurs between two 
nuclei which originate in a single nucleus of an individual. This 
process has been called automixis by Hartmann, in contrast to the 
amphimixis (Weismann) which is the complete fusion of two nuclei 
originating in two individuals, as was discussed in the preceding 
pages. If the two nuclei which undergo a complete fusion are present 
in a single cell, the process is called autogamy, but, if they are in two 


different cells, then paedogamy. The autogamy is of common occur- 
rence in the myxosporidian spores. The young sporoplasm contains 
two nuclei which fuse together prior to or during the process of ger- 
mination in the alimentary canal of a specific host fish, as for exam- 
ple in Sphaeromyxa sabrazesi (Figs. 276; 277) and Myxosoma cato- 
stomi (Fig. 275). In the Microsporidia, autogamy appears to initiate 
the spore-formation at the end of schizogonic activity of individuals 
as in Thelohania legeri (Fig. 76). 

Diller (1936) observed in solitary Paramecium aurelia (Fig. 89), 
certain micronuclear changes similar to those which occur in 
conjugating individuals. The two micronuclei divide twice, form- 
ing eight nuclei (a-d), some of which divide for the third time (e), 
producing two functional and several degenerating nuclei (/). The 
two functional nuclei then fuse in the "paroral cone" and form the 
synkaryon (g, h) which divides twice into four (i, j). The original 
macronucleus undergoes fragmentation and becomes absorbed in the 
cytoplasm. Of the four micronuclei, two transform into the new 
macronuclei and two remain as micronuclei (k) each dividing into 
two after the body divided into two (Z). 

Another sexual process appears to have been observed by Diller 
(1934) in conjugating Paramecium trichium in which there was 
no nuclear exchange between the two conjugants. Wichterman 
(1940) observed a similar process in P. caudatum and named it cytog- 
amy. Two small (about 200/x long) individuals of P. caudatum 
fuse on their oral surfaces. There occur three micronuclear divisions 
as in the case of conjugation, but there is no nuclear exchange be- 
tween the members of the pair. The two gametic nuclei in each indi- 
vidual are said to fuse and form a synkaryon as in autogamy. Sonne- 
born (1941) finds the frequency of cytogamy in P. aurelia to be cor- 
related with temperature. At 17°C, conjugation occurs in about 95 
per cent of the pairs and cytogamy in about 5 per cent; but at 10° 
and 27°C, cytogamy takes place in 47 and 60 per cent respectively. 
In addition, there is some indication that sodium decreases and 
calcium increases the frequency of occurrence of cytogamy. 

The paedogamy occurs in at least two species of Myxosporidia, 
namely, Leptotheca ohlmacheri (Fig. 279) and Unicapsula muscularis 
(Fig. 280). The spores of these myxosporidians contain two uninu- 
cleate sporoplasms which are independent at first, but prior to 
emergence from the spore, they undergo a complete fusion to meta- 
morphose into a uninucleate amoebula. Perhaps the classical exam- 
ple of the paedogamy is that which was found by Hertwig (1898) in 
Actinosphaerium eichhorni. The organism encysts and the body di- 



vides into numerous uninucleate secondary cysts. Each secondary 
cyst divides into two and remains together within a common cyst- 
wall. In each the nucleus divides twice, and forms four nuclei, one of 
which remains functional, the remaining three degenerating. The 
paedogamy results in formation of a zygote in place of a secondary 
cyst. Belaf (1923) observed a similar process in Actinophrys sol 
(Fig. 90). This heliozoan withdraws its axopodia and divides into 
two uninucleate bodies which become surrounded by a common 

Fig. 90. Paedogamy in Actinophrys sol, X460 (Belaf). a, withdrawal 
of axopodia; b, c, division into two uninucleate bodies, surrounded by 
a common gelatinous envelope; d-f, the first reduction division; g-i, 
the second reduction division; j-1, synkaryon formation. 

gelatinous envelope. Both nuclei divide twice and produce four nu- 
clei, three of which degenerate. The two daughter cells, each with one 
haploid nucleus, undergo paedogamy and the resulting individual 
now contains a diploid nucleus. 

In Paramecium aurelia, Diller (1936) found simple fragmentation 
of the macronucleus which was not correlated with any special 
micronuclear activity and which could not be stages in conjugation 
or autogamy. Diller suggests that if conjugation or autogamy is to 
create a new nuclear complex, as is generally held, it is conceivable 
that somewhat the same result might be achieved by "purification 
act" (through fragmentation) on the part of the macronucleus itself, 



without involving micronuclei. He coined the term hemixis for this 

Meiosis. In the foregoing sections, references have been made to 
the divisions which the nuclei undergo prior to sexual fusion or con- 
jugation. In all Metazoa, during the development of the gametes, 
the gametocytes undergo reduction division or meiosis, by which the 
number of chromosomes is halved; that is to say, each fully mature 
gamete possesses half (haploid) number of chromosomes typical of 
the species (diploid). In the zygote, the diploid number is reestab- 
lished. In the Protozoa in which sexual reproduction occurs during 
their life-cycle, meiosis presumably takes place to maintain the con- 
stancy of chromosome-number, but the process is understood only 
in a small number of species. 

Fig. 91. Mitotic and meiotic micronuclear divisions in conjugating 
Didinium nasutum. (Prandtl, modified), a, normal micronucleus;b, equa- 
torial plate in the first (mitotic) division; c, anaphase in the first division; 
d, equatorial plate in the second division; e, anaphase in the second 
(meiotic) division. 

In conjugation, the meiosis seems to take place in the second 
micronuclear division, although in some, for example, Oxytricha 
fallax, according to Gregory, the actual reduction occurs during the 
first division. Prandtl (1906) was the first to note a reduction in 
number of chromosomes in the Protozoa. In conjugating Didinium 
nasutum (Fig. 91), he observed 16 chromosomes in each of the 
daughter micronuclei during the first division, but only 8 in the 
second division. Since that time, the fact that meiosis occurs during 
the second micronuclear division has been observed in Chilodonella 
uncinata (Enrique; MacDougall), Carchesium polypinum (Popoff), 
Uroleptus halseyi (Calkins), etc. (note the ciliates in Table 5 on p. 
168). In various species of Paramecium and many other forms, the 
number of chromosomes appears to be too great to allow a precise 
counting, but the observations of Sonneborn, as quoted elsewhere 
(p. 234) and of Jennings (1942) on P. aurelia and P. bursaria respec- 



tively, indicate clearly the occurrence of meiosis prior to nuclear ex- 
change during conjugation. 

Information on the meiosis involved in the complete fusion of gam- 
etes is even more scanty and fragmentary. In Monocystis rostrata 
(Fig. 92), a parasite of the earthworm, Mulsow (1911) noticed that 

f ' ^^V 





Fig. 92. Mitosis and meiosis in Monocystis rostrata (Mulsow). a-g, 
mitosis; h-j, meiosis. a, a resting nucleus in the gametocyte; b, develop- 
ment of chromosomes; c, polar view of equatorial plate; d, longitudinal 
splitting of eight chromosomes; e, separation of chromosomes in two 
groups; f, late anaphase; g, two daughter nuclei; h, i, polar view of the 
equatorial plate in the last division; j, anaphase, the gamete nucleus is 
now haploid (4). a-c, X1840; d-g, X1400; h-j, X3000. 

the nuclei of two gametocytes which encyst together, multiply by 
mitosis in which eight chromosomes are constantly present (a-g), 
but in the last division in gamete formation, each daughter nucleus 
receives only 4 chromosomes (h-j). In another species of Monocystis, 
Calkins and Bowling (1926) observed that the diploid number of 
chromosomes was 10 and that haploid condition is established in the 
last gametic division thus confirming Mulsow's finding. 

In the paedogamy of Actinophrys sol (Fig. 90), Belaf (1923) finds 
44 chromosomes in the first nuclear division, but after two meiotic 
divisions, the remaining functional nucleus contains only 22 chromo- 
somes so that when paedogamy is completed the diploid number is 
restored. In Polytoma uvella, Moewus finds each of the two gametes 
is haploid (8 chromosomes) and the zygotes are diploid. The syn- 
karyon divides twice, and during the first division reduction division 
takes place. 



In the coccidian, Aggregata eberthi (Fig. 246), according to Dobell 
(1925), Naville (1925) and Belaf (1926) and in the gregarine, Diplo- 
cystis schneideri, according to Jameson (1920), there is no reduction 
in the number of chromosomes during the gamete-formation, but the 
first zygotic division is meiotic, 12 to 6 and 6 to 3, respectively. A 
similar reduction takes place also in Actinocephalus parvus (8 to 4, 
after Weschenf elder, 1938), Greg arina blattarum (6 to 3, after Sprague, 
1941), Adelina deronis (20 to 10, after Hauschka, 1943), etc. Tri- 
chonympha and other flagellates (p. 185) of woodroach, Polytoma 

Fig. 93. Degeneration or aging in Stylonychia pustulata. X340 (Maupas, 
modified), a, Beginning stage with reduction in size and completely 
atrophied micronucleus; b, c, advanced stages in which disappearance of 
the frontal zone, reduction in size, and fragmentation of the macronucleus 
occurred; d, final stage before disintegration. 

and Chlamydomonas (p. 276) also undergo postzygotic meiosis. 
Thus in these organisms, the zygote is the only stage in which the 
nucleus is diploid. 

Some seventy years ago Weismann pointed out that a protozoan 
grows and muliplies by binary fission or budding into two equal or 
unequal individuals without loss of any protoplasmic part and these 
in turn grow and divide, and that thus in Protozoa there is neither 
senescence nor natural death which occur invariably in Metazoa in 
which germ and soma cells are differentiated. Since that time, the 
problem of potential immortality of Protozoa has been a matter 
which attracted the attention of numerous investigators. Because of 
large dimensions, rapid growth and reproduction, and ease with 


which they can be cultivated in the laboratory, the majorhVy of 
Protozoa used in the study of the problem have been free-living 
freshwater ciliates that feed on bacteria and other microorganisms. 

The very first extended study was made by Maupas (1888) who 
isolated Stylonychia pustulata on February 27, 1886, and observed 
316 binary fissions until July 10. During this period, there was noted 
a gradual decrease in size and increasing abnormality in form and 
structure, until the animals could no longer divide and died (Fig. 
93). A large number of isolation culture experiments have since been 
carried on numerous species of ciliates by many investigators. The 
results obtained are not in agreement. However, the bulk of ob- 
tained data indicates that the vitality of animals decreases with the 
passing of generations until finally the organisms suffer inevitable 
death, and that in the species in which conjugation or other sexual 
reproduction occurs, the declining vitality often becomes restored. 
Perhaps the most thorough experiment was carried on by Calkins 
(1919, 1933) with Uroleptus mobilis. Starting with an exconjugant on 
November 17, 1917, a series of pure-line cultures was established by 
the daily isolation method. It was found that no series lived longer 
than a year, but when two of the progeny of a series were allowed to 
conjugate after the first 75 generations, the exconjugants repeated 
the history of the parent series, and did not die when the parent 
series died. In this way, lines of the same organism have lived for 
more than 12 years, passing through numerous series. In a series, 
the average division for the first 60 days was 15.4 divisions per 10 
days, but the rate gradually declined until death. Woodruff and 
Spencer (1924) also found the isolation cultures of Spathidium 
spathula (fed on Colpidium colpoda) died after a gradual decline in 
the division rate, but were inclined to think that improper environ- 
mental conditions rather than internal factors were responsible for 
the decline. 

On the other hand, Woodruff (1932) found that 5071 generations 
produced by binary fission from a single individual of Paramecium 
aurelia between May 1, 1907 and May 1, 1915, did not manifest any 
decrease in vitality after eight years of continued asexual reproduc- 
tion. Other examples of longevity of ciliates without conjugation 
are: Glaucoma for 2701 generations (Enriques, 1916), Paramecium 
caudatum for 3967 generations (Metalnikov, 1922), Spathidium spa- 
thula for 1080 generations (Woodruff and Moore, 1924), Didinium 
nasutum for 1384 generations (Beers, 1929), etc. With Actinophrys 
sol, Belaf (1924) carried on isolation cultures for 1244 generations for 
a period of 32 months and noticed no decline in the division rate. 


Hartmann (1921) made a similar observation on Eudorina 

It would appear that in these forms, the life continues indefinitely 

without apparent decrease in vital activity. 

As has been noted in the beginning part of the chapter, the 
macronucleus in the ciliates undergoes, at the time of binary fission 
a reorganization process before dividing into two parts and undoubt- 
edly, there occurs at the same time extensive cytoplasmic reorgani- 
zation as judged by the degeneration and absorption of the old, and 
formation of the new, organellae. It is reasonable to suppose that 
this reorganization of the whole body structure at the time of divi- 
sion is an elimination process of waste material accumulated by the 
organism during the various phases of vital activities as was con- 
sidered by Kidder and others (p. 150) and that this elimination, 
though not complete, enables the protoplasm of the products of divi- 
sion to carry on their metabolic functions more actively. 

As the generations are multiplied, the general decline in vitality 
is manifest not only in the decreased division-rate, slow growth, 
abnormal form and function of certain organellae, etc., but also in 
inability to complete the process involved in conjugation. Jennings 
(1944) distinguished four successive periods in various clone cultures 
of Paramecium bursaria; namely, (1) a period of sexual immaturity 
during which neither sexual reaction nor conjugation occurs; (2) a 
period of transition during which weak sexual reactions appear in a 
few individuals; (3) a period of maturity in which conjugation takes 
place readily when proper mating types are brought together; and 
(4) a period of decline, ending in death. The length of the first two 
periods depends on the cultural conditions. Exconjugant clones that 
are kept in condition under which the animals multiply rapidly, 
reach maturity in three to five months, while those subjected to de- 
pressing condition require 10 to 14 months to reach maturity. The 
third period lasts for several years and is followed by the fourth 
period during which fission becomes slower, abnormalities appear, 
many individuals die and the clones die out completely. 

Does conjugation affect the longevity of clones in Paramecium 
busaria? A comparative study of the fate of exconjugants and non- 
conjugants led Jennings (1944a) to conclude that (1) conjugation 
results in production of one of the following four types: (a) excon- 
jugants perish without division, (b) exconjugants divide one to four 
times and then die, (c) exconjugants produce weak abnormal clones 
which may become numerous, and (d) exconjugants multiply vigor- 
ously and later undergo conjugation again; at times the latter are 


more vigorous than the parent clones, thus showing rejuvenescence 
through conjugation; (2) conjugation of young clones results in little 
or no mortality, while that of old clones results in high (often 100 per 
cent) mortality; (3) conjugation between a young and an old clone, 
results in the death of most or all of the exconjugants; (4) the two 
members of a conjugating pair have the same fate; and (5) what 
other causes besides age bring about the death, weakness or ab- 
normality of the exconjugants, are not known. 

It is probable that the process of replacing old macronuclei by 
micronuclear material which are derived from the products of fusion 
of two micronuclei of either the same (autogamy) or two different 
animals (conjugation), would perhaps result in a complete elimina- 
tion of waste substances from the newly formed macronuclei, and 
divisions which follow this fusion may result in shifting the waste 
substances unequally among different daughter individuals. Thus in 
some individuals there may be a complete elimination of waste 
material and consequently a restored high vitality, while in others 
the influence of waste substances present in the cytoplasm may offset 
or handicap the activity of new macronuclei, giving rise to stocks of 
low vitality which will perish sooner or later. In addition in conjuga- 
tion, the union of two haploid micronuclei produces diverse genetic 
constitutions which would be manifest in progeny in manifold 
ways. Experimental evidences indicate clearly such is actually the 

In many ciliates, the elimination of waste substances at the time 
of binary fission and sexual reproduction (conjugation, and autog- 
amy), seemingly allow the organisms continued existence through 
a long chain of generations indefinitely. Jennings (1929, 1942) who 
reviewed the whole problem states: "Some Protozoa are so con- 
stituted that they are predestined to decline and death after a 
number of generations. Some are so constituted that decline occurs, 
but this is checked or reversed by substitution of reserve parts 
for those that are exhausted; they can live indefinitely, but are 
dependent on this substitution. In some the constitution is such 
that life and multiplication can continue indefinitely without visible 
substitution of a reserve nucleus for an exhausted one; but whether 
this is due to the continued substitution, on a minute scale, of re- 
serve parts for those that are outworn cannot now be positively 
stated. This perfected condition, in which living itself includes con- 
tinuously the necessary processes of repair and elimination, is found 
in some free cells, but not in all." 



The capacity of regenerating the lost parts, though variable 
among different species, is characteristic of all Protozoa from simple 
forms to those with highly complex organizations, as shown by ob- 
servations of numerous investigators. It is now a well established 
fact that when a protozoan is cut into two parts and the parts are 
kept under proper environmental conditions, the enucleated portion 
is able to carry on catabolic activities, but unable to undertake ana- 
bolic activities, and consequently degenerates sooner or later. Brandt 
(1877) studied regeneration in Actinosphaerium eichhorni and found 
that only nucleate portions containing at least one nucleus regener- 
ated and enucleate portions or isolated nuclei degenerated. Similarly 
Gruber (1886) found in Amoeba proteus the nucleate portion regener- 
ated completely, while enucleate part became rounded and perished 
in a few days. The parts which do not contain nuclear material may 
continue to show certain metabolic activities such as locomotion, 
contraction of contractile vacuoles, etc., for some time; for example, 
Grosse-Allermann (1909) saw enucleate portions of Amoeba verrucosa 
alive for 20 to 25 days, while Stole (1910) found enucleate Amoeba 
proteus living for 30 days. Clark (1942, 1943) showed that Amoeba 
proteus lives for about seven days after it has been deprived of its 
nucleus. Enucleated individuals show a 70 per cent depression of 
respiration and are unable to digest food due to the failure of zymo- 
gens to be activated in the dedifferentiating cytoplasm. According to 
Brachet (1950), the enucleated half of an amoeba shows a steady 
decrease in ribonucleic acid content, while the nucleated half retains 
a much larger amount of this substance. Thus it appears that the 
synthesis of the cytoplasmic particles containing ribonucleic acid is 
under the control of the nucleus. 

In Arcella (Martini; Hegner) and Difflugia (Verworn; Penarcl), 
when the tests are partially destroyed, the broken tests remain un- 
changed. Verworn considered that in these testaceans test-forming 
activity of the nucleus is limited to the time of asexual reproduction 
of the organisms. On the other hand several observers report in 
Foraminifera the broken shell is completely regenerated at all times. 
Verworn pointed out that this indicates that here the nucleus con- 
trols the formation of shell at all times. In a radiolarian, Thalassi- 
colla nucleata, the central capsule, if dissected out from the rest of 
body, will regenerate into a complete organism (Schneider). A few 
regeneration studies on Sporozoa have not given any results to be 
considered here, because of the difficulties in finding suitable media 
for cultivation in vitro. 


An enormous number of regeneration experiments have been con- 
ducted on more than 50 ciliates by numerous investigators. Here 
also the general conclusion is that the nucleus is necessary for re- 
generation. In many cases, the macronucleus seems to be the only 
essential nucleus for regeneration, as judged by the continued divi- 
sion on record of several amicronucleate ciliates and by experiments 
such as Schwartz's in which there was no regeneration in Stentor 
coeruleus from which the whole macronucleus had been removed. 

A remarkably small part of a protozoan is known to be able to re- 
generate completely if nuclear material is included. For example, 
Sokoloff found 1/53-1/69 of Spirostomum ambiguum and 1/70-1/75 
of Dileptus anser regenerated and Phelps showed portions down to 
1/80 of an amoeba were able to regenerate. In Stentor coeruleus, 
pieces as small as 1/27 (Lilly) or 1/64 (Morgan) of the original speci- 
mens or about 70/jl in diameter (Weisz) regenerate. Burnside cut 27 
specimens of this ciliate belonging to a single clone, into two or more 
parts in such a way that some of the pieces contained a large portion 
of the nucleus while others a small portion. These fragments re- 
generated and multiplied, giving rise to 268 individuals. No dimen- 
sional differences resulted from the different amounts of nuclear 
material present in the cut specimens. Apparently regulatory pro- 
cesses took place and in all cases normal size was restored, re- 
gardless of the amount of the nuclear material in ancestral pieces. 
Thus biotypes of diverse sizes are not produced by causing inequali- 
ties in the proportions of nuclear material in different individuals. 

In addition to these restorative regenerations, there are physio- 
logical regenerations in which as in the case of asexual and sexual re- 
production, various organellae such as cilia, flagella, cytostome, 
contractile vacuoles, etc., are completely regenerated. Information is 
now available on the process of morphogenesis in regeneration and 
reorganization in certain ciliates (Chatton and Lwoff, 1935; Bala- 
muth, 1940; Summers, 1941; Faure-Fremiet, 1948; Weisz, 1948, 


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■ (1940b) Conjugation of three animals in Paramecium bur- 
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(1940c) Conjugation in Paramecium bursaria between ani- 
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— (1950) II. Ibid., 86:185. 
- (1950a) III. Ibid., 86:215. 


(1950b) IV. Ibid., 87:317. 

(1950c) V. Ibid., 87:349. 

(1951) VI. Ibid., 88:199. 

(1951a) VII. Ibid., 88:385. 

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Paramecium aurelia and double-monsters of P. caudatum. Am. 
Nat., 69:87. 

Diller, W. F.: (1936) Nuclear reorganization processes in Para- 
mecium aurelia, etc. J. Morphol., 59:11. 

(1948) Nuclear behavior of Paramecium trichium during con- 
jugation. Ibid., 82:1. 

(1950) An extra postzygotic nuclear division in Paramecium 

caudatum. Tr. Am. Micr. Soc, 69:309. 

(1950a) Cytological eivdence for pronuclear interchange in 

Paramecium caudatum. Ibid., 69:317. 
Dobell, C. : (1908) The structure and life history of Copromonas 

subtilis, etc. Quart. J. Micr. Sc, 52:75. 

(1917) On Oxnerella maritima, etc. Ibid., 62:515. 

(1925) The life history and chromosome cycle of Aggregata 

eberthi. Parasitology, 17:1. 
(1928) Researches on the intestinal Protozoa of monkeys and 

man. I, II. Ibid., 20:357. 

and Laidlaw, P. P.: (1926) On the cultivation of Entamoeba 

histolytica, etc. Ibid., 18:283. 
Enriques, P.: (1916) Duemila cinquecento generazioni in un in- 
fusorio, senza conjugazione ne partenogenesi, ne depressioni. 
Rev. Acad. Sc. Bologna, 20:67. 


Entz, G.: (1925) Ueber Cysten und Encystierung der Siisswasser- 

Ceratien. Arch. Protist., 51:131. 
Everritt, Martha G.: (1950) The relationship of population 

growth, etc. J. Parasit., 36:586. 
Faure-Fremiet, E.: (1948) Les mecanismes de la morphogenese 

chez les cilies. Folia Bioth., 3:25. 
Finley, H. E.: (1936) A method for inducing conjugation within 

Vorticella cultures. Tr. Am. Micr. Soc, 55:323. 
(1943) The conjugation of Vorticella microstoma. Ibid., 62: 

Frosch, P.: (1897) Zur Frage der Reinzuchtung der Amoeben. Zen- 

tralbl. Bakt. I. Abt., 21:926. 
Garnjobst, L.: (1928) Induced encystment and excystment in 

Ewplotes taylori, etc. Physiol. Zool., 1:561. 
Giese, A. C.: (1938) Size and conjugation in Blepharisma. Arch. 

Protist., 91:125. 
(1939) Studies on conjugation in Paramecium multimicro- 

nucleatum. Am. Nat., 73:432. 
(1939a) Mating types in Paramecium caudatum. Am. Nat., 

Gilman, L. C.: (1941) Mating types in diverse races of Paramecium 

caudatum. Biol. Bull., 80:384. 
Grasse, P.-P.: (1952) Traite de Zoologie. I. Fasc. 1. Paris. 
Guilcher, Yvette: (1950) Contribution a l'etude des cilies gemmi- 

pares, etc. Univ. de Paris thesis, Ser. A. no. 2369. 
Haagen-Smit, A. J. and Thimann, K. V.: (1938) The excystment of 

Colpoda cucullus. I. J. Cell. Comp. Physiol., 11:389. 
Hall, R. P.: (1923) Morphology and binary fission of Menoidium 

incurvum. Univ. California Publ. Zool., 20:447. 
(1937) A note on behavior of the chromosomes in Euglena. 

Tr. Am. Micr. Soc, 56:288. 
Hartmann, M.: (1917) Ueber die dauernde rein agame Zuchtung 

von Eudorina elegans, etc. Ber. preuss. Akad. Wiss., Phys.- 

Math. Kl., p. 760. 
Hauschka, T. S.: (1943) Life history and chromosome cycle of the 

coccidian, Adelina deronis. J. Morphol., 73:529. 
Hertwig, R.: (1889) Ueber die Conjugation der Infusorien. Abh. 

bayerl. Akad. Wiss., 17:151. 
Hinshaw, H. C: (1926) On the morphology and mitosis of Tri- 
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Hiwatashi, K.: (1949) Studies on the conjugation of Paramecium, 

caudatum. I. Sc. Rep. Tohoku Univ. Ser. IV, 18:137. 

(1949a) II. Ibid., 18:141. 

(1950) III. Ibid., 18:270. 

(1951) IV. Ibid., 19:95. 

Horvath, J.: (1950) Vitalitatsausserung einer mikronucleuslose 

Bodenziliate in der vegetativen Fortpflanzung. Oesterr. zool. 

Ztschr., 2:336. 
Ilowaisky, S. A.: (1926) Material zum Studium der Cysten der 

Hypotrichen. Arch. Protist., 54:92. 


Ivanic, M. : (1934) Ueber die Ruhestadienbildung und die damit am 
Kernapparate verbundenen Veranderungen bei Lionotus cygnus. 
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(1938) Ueber die mit der Chromosomenbildung verbundene 

promitotische Grosskernteilung bei den Vermehrungsruhe Sta- 
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Jameson, A. P.: (1920) The chromosome cycle of gregarines with 
special reference to Diplocystis schneideri. Quart. J. Micr. Sc, 

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— ■ (1938) Sex relation types and their inheritance in Parame- 
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(1939) Genetics of Paramecium bursaria. I. Genetics, 24:202. 

(1941) II. Proc. Am. Philos. Soc, 85:25. 

(1942) III. Genetics, 27:193. 

(1942a) Senescence and death in Protozoa and invertebrates. 

E. V. Cowdry's Problems of ageing. 2 ed. Baltimore. 

(1944) Paramecium bursaria: Life history. I. Biol. Bull., 86: 


■ (1944a) II. J. Exper. Zool., 96:17. 

and Opitz, Pauline: (1944) Genetics of Paramecium bur- 
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Raffel, D., Lynch, R. S. and Sonneborn, T. M.: (1932) 

The diverse biotypes produced by conjugation within a clone of 

Paramecium aurelia. J. Exper. Zool., 62:363. 
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Zool. Anz., 7:491. 
Johnson, W. H. and Evans, F. R.: (1940) Environmental factors 

affecting encystment in Woodruffia metabolica. Physiol. Zool., 

— — — (1941) A further study of environmental factors af- 
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Kidder, G. W. : (1933) Studies on Conchophthirus mytili de Morgan. 

I. Arch. Protist., 79:1. 
(1938) Nuclear reorganization without cell division in Para- 

clevelandia simplex, etc. Ibid., 91:69. 
and Claff, C. L.: (1938) Cytological investigations of Gol- 

poda cucullus. Biol. Bull., 74:178. 
and Diller, W. F. : (1934) Observations on the binary fission 

of four species of common free-living ciliates, etc Ibid., 67:201. 
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Physiol. Zool., 12:341. 
and Summers, F. M.: (1935) Taxonomic and cytological 

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Biol. Bull, 68:51. 


Kimball, R. F.: (1939) Change of mating type during vegetative 
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(1939a) Mating types in Euplotes. Amer. Nat., 73:451. 

(1941) The inheritance of mating type in the ciliate protozoan 

Euplotes patella. Genetics, 26:158. 

(1941a) Double animals and amicronucleate animals, etc. 

J. Exper. Zool., 86:1. 

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plotes patella. Genetics, 27:269. 
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the termites. I. Univ. California Publ. Zool., 20:1. 

(1919a) III. Ibid., 20:41. 

Korschelt, E.: (1927) Regeneration und Transplantation. Vol. 1. 

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— (1936) Studies on Nyctotherus ovalis, etc. Ibid., 87:10. 
(1947) Pelomyxa carolinensis Wilson. II. J. Morphol., 80: 


■ (1951) Observations on Pelomyxa illinoisensis. Ibid., 88: 

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Amoeba proteus. Ibid., 91:135. 
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Bursaria. J. Exper. Zool., 24:1. 
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(1889) Le rejeunissement karyogamique chez les cilies. Ibid., 


Metalnikov, S.: (1922) Dix aus de culture des infusoires sans con- 

jugasion. C. R. Acad. Sc, 175:776. 
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substance of Paramecium aurelia variety 4. Anat. Rec, 93:347. 
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mecium aurelia by formalin killed animals of opposite mating 

type. J. Exp. Zool., 105:115. 
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substances. Am. Nat., 82:85. 
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reaction inhibiting sgent from Paramecium calkinsi. Proc. Nat. 

Acad. Sc, 36:268. 
Mouton, H.: (1902) Recherches sur la digestion chez les amibes, 

etc. Ann. Inst. Pasteur, 16:457. 
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gata. Rev. Suiss. Zool., 32:125. 
Noble, E. R. : (1947) Cell division in Entamoeba gingivalis. Univ. 

California Publ. Zool., 53:263. 
Noland, L. E.: (1927) Conjugation in the ciliate Metopus sygmoides. 

J. Morphol. Physiol., 44:341. 
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Didinium nasutum. Proc. Soc. Exper. Biol., 18:188. 
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plotes patella. Am. Midland Nat., 30:175. 
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Arch. Protist., 7:251. 
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Uni. Mar. Curie-Ski., Lublin, Sec. C, 1:18. 

(1947) II. Ibid., 1:151. 

Rafalko, J. S.: (1947) Cytological observations on the amoebo- 

flagellate, Naegleria gruberi. J. Morphol., 81:1. 
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tozoen. Arch. Protist., 61:144. 
(1929) In: Doflein-Reichenow's Lehrbuch der Protozoen- 

kunde. Jena. 
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infusorian. J. Exper. Zool, 62:327. 
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Entwicklungsgeschichte der holotrichen Infusoriengattung Col- 

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Tr. Am. Micr. Soc, 57:147. 


Schmahl, O.: (1926) Die Neubildung des Peristoms bei der Teilung 
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Singh, B. N.: (1941) The influence of different bacterial food sup- 
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Sokoloff, B.: (1924) Das Regenerationsproblem bei Protozoen. 
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Sonneborn, T. M. : (1937) Sex, sex inheritance and sex determina- 
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(1939) Paramecium aurelia: mating types and groups, etc. 

Am. Nat., 73:390. 

(1940) The relation of macronuclear regeneration in Para- 
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(1941) The occurrence, frequency and causes of failure to 

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— — — (1942) Sex hormones in unicellular organisms. Cold Spr. 
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(1942a) Inheritance in ciliate Protozoa. Am. Nat., 76:46. 

(1943) Gene and cytoplasm. I. Proc. Nat. Acad. Sc, 29: 


(1943a) II. Ibid., 29:338. 

(1944) Exchange of cytoplasm at conjugation in Paramecium 

aurelia, variety 4. Anat. Rec, 89:49. 

(1947) Recent advances in the genetics of Paramecium and 

Euplotes. Adv. Genetics, 1:263. 

(1950) The cytoplasm in heredity. Heredity, 4:11. 

and Dippell, Ruth V.: (1943) Sexual isolation, mating 

types, and sexual responses to diverse conditions in variety 4, 
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(1946) Mating reactions and conjugation between 

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Sprague, V.: (1941) Studies on Gregarina blatlarum, etc., 111. Biol. 

Monogr., 18, no. 2. 
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studies on ciliates. III. Physiol. Zool., 12:348. 
Summers, F. M.: (1935) The division and reorganization of the 

macronuclei of Aspidisca lynceus, etc Arch. Protist., 85: 173. 
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Taylor, C. V. and Strickland, A. G. R.: (1938) Reactions of Col- 

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Thimann, K. V. and Barker, H. A.: (1934) Studies on the excyst- 

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Arch. Protist., 5:282. 
Turner, J. P.: (1930) Division and conjugation in Euplotes patella, 

etc. Univ. California Publ. Zool., 33:193. 
von Brand, T. : (1923) Die Encystierung bei Vorticella microstoma 

und hypotrichen Infusorien. Arch. Protist., 47:59. 
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regneration of Stentor fragments. J. Exper. Zool., 107:269. 
(1950) Multiconjugation in Blepharisma. Biol. Bull., 98: 

(1950a) A correlation between macronuclear thymonucleic 

acid concentration and the capacity of morphogenesis in Sten- 
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coeruleus. J. Exper. Zool., 116:231. 
(1951a) A general mechanism of differentiation based on 

morphogenetic studies in ciliates. Am. Nat., 85:293. 
Wenrich, D. H.: (1939) Studies on Dientamoeba fragilis. III. J. 

Parasitol., 25:43. 
Weschenfelder, R.: (1938) Die Entwicklung von Actinocephalus 

parvus. Arch. Protist., 91:1. 
Wichterman, R. : (1936) Division and conjugation in Nyctotherus 

cordiformis, etc. J. Morphol., 60:563. 
(1940) Cytogamy: a sexual process occurring in living joined 

pairs of Paramecium caudatum, etc. Ibid., 66:423. 

(1946) Further evidence of polyploidy in the conjugation of 

green and colorless Paramecium bursaria. Biol. Bull., 91:234. 
Wilson, E. B.: (1928) The cell in development and heredity. New 

Wolff, E.: (1927) Un facteur de l'enkystment des amibes d'eau 

douce. C. R. Soc. Biol., 96:636. 
Woodruff, L. L.: (1921) Micronucleate and amicronucleate races 

of Infusoria. J. Exper. Zool., 34:329. 
(1931) Micronuclear variation in Paramecium bursaria. 

Quart. J. Micr. Sc, 74:537. 
(1932) Paramecium aurelia in pedigree culture for 25 years. 

Tr. Am. Micr. Soc, 51:196. 
and Erdmann, Rhoda: (1914) A normal periodic reorganiza- 
tion process without cell fusion in Paramecium. J. Exper. Zool., 

and Spencer, H.: (1921) The survival value of conjugation 

in the life history of Spathidium spathula. Proc. Soc. Exper. 

Biol., 18:303. 

Chapter 6 
Variation and heredity 

IT IS generally recognized that individuals of all species of organ- 
ism vary in morphological and physiological characteristics. Pro- 
tozoa are no exception, and manifest a wide variation in size, form, 
structure, and physiological characters among the members of a 
single species. The different groups in a species are spoken of as the 
races, varieties, strains, etc. It is well known that dinoflagellates 
show a great morphological variation in different localities. Wesen- 
berg-Lund (1908) noticed a definite seasonal morphological variation 
in Cerctium hirundinella in Danish lakes, while Schroder (1914) 
found at least nine varieties of this organism (Fig. 94) occurring in 
various bodies of water in Europe, and List (1913) reported that the 
organisms living in shallow ponds possess a marked morphological 
difference from those living in deep ponds. Cyphoderia ampulla is 
said to vary in size among those inhabiting the same deep lakes; 
namely, individuals from the deep water may reach 200m in length, 
while those from the surface layer measure only about 100^ long. 

In many species of Foraminifera, the shell varies in thickness ac- 
cording to the part of ocean in which the organisms live. Thus the 
strains which live floating in surface water have a much thinner shell 
than those that dwell on the bottom. For example, according to 
Rhumbler, Orbulina universa inhabiting surface water has a com- 
paratively thin shell, 1.28-18^ thick, while individuals living on the 
bottom have a thick shell, up to 24/x in thickness. According to 
Uyemura, a species of Amoeba living in thermal waters, showed a 
distinct dimensional difference in different springs. It measured 
10— 40/x in diameter in sulphurous water and 45-80^ in ferrous water; 
in both types of water the amoebae were larger at 36-40°C. than 
at 51°C. 

Such differences or varieties appear to be due to the influence of 
diverse environmental conditions, and will continue to exist under 
these conditions; but when the organisms of different varieties are 
subjected to a similar environment, the strain differences usually dis- 
appear sooner or later. That the differences in kind and amount of 
foods bring about extremely diverse individuals in Tetrahymena 
vorax and Chilomonas Paramecium in bacteria-free cultures has al- 
ready been mentioned (p. 109). Chlamydomonas debaryana are repre- 
sented by many races differing in form, size, and structure, in various 
localities as well as under different laboratory conditions. Moewus 




(1934) distinguished 12 such varieties and showed that any variety 
could be changed into another by using different culture media. This 
transformation, however, did not occur at the same rate among dif- 
ferent races. It was found that the longer a strain has remained under 

Fig. 94. Varieties of Ceratium hirundinella from various European 
waters (Schroder), a, furcoides-type (130-300> by 30-45/x); b, brachy- 
ceroides-type (130-145/z by 30-45^); c, silesiacum-type (148-280/x by 
28— 34ju) ; d, carinthiacum-type (120-145/z by 45-60/x); e, gracile-type 
(140-200/* by 60-75/x); f, austriacum-type (120-160/x by 45-60/x); g, 
robustum-type (270-310/x by 45-55/x); h, scotticum-type (160-210/z by 
50-60m); i, piburgense-type (180-260/* by 50-60/x). 

conditions producing a given type, the greater the time and the num- 
ber of generations needed to change it to a new type under a new 
condition, as is shown in Table 9. 

While in many species, the races or varieties have apparently been 
brought about into being under the influence of environmental con- 
ditions, in others the inherited characters persist for a long period, 
and still in others the biotype may show different inherited char- 


Table 9. — Relation between the number of days cultivated in peptone 
medium and the number of days cultivated in salt-sugar medium needed to 
change from type 1 to type 5 in Chlamydomonas debaryana (Moewus). 

Days in peptone medium 

Days in salt-sugar medium needed 

as type 1 

to change to type 5 



















acters. To the last-mentioned category belongs perhaps a strain of 
Tetrahymena pyriformis in which, according to Furgason (1940), a 
pure-line bacteria-free culture derived from a single individual was 
found to be composed of individuals differing in shape and size which 
became more marked in older cultures. 

The first comprehensive study dealing with the variation in 
size and its inheritance in asexual reproduction of Protozoa was 
conducted by Jennings (1909). From a "wild" lot of Paramec- 
ium caudatum, eight races or biotypes with the relative mean 
lengths of 206, 200, 194, 176, 142, 125, 100, and 45/x were isolated. 
It was found that within each clone derived from a single parent, 
the size of individuals varies greatly (which is attributable to 
growth, amount of food, and other environmental conditions), any 
one of which may give rise to progeny of the same mean size. Thus 
selection within the pure race has no effect on the size, and the differ- 
ences brought about merely by environment are not inherited. Jen- 
nings (1916) examined the inheritance of the size and number of 
spines, size of shell, diameter of mouth, and size and number of 
teeth of the testacean Difflugia corona, and showed that "a popula- 
tion consists of many hereditarily diverse stocks, and a single stock, 
derived from a single progenitor, gradually differentiates into such 
hereditarily diverse stocks, so that by selection marked results are 
produced." Root (1918) with Centropyxis aculeata, Hegner (1919) 
with Arcella dentata, and Reynolds (1924) with A. polypora, ob- 
tained similar results. Jennings (1937) studied the inheritance of 
teeth in Difflugia corona in normal fission and by altering through 
operation, and found that operated mouth or teeth were restored to 


normal form in 3 or 4 generations and that three factors appeared to 
determine the character and number of teeth: namely, the size of the 
mouth, the number and arrangement of teeth in the parent, and 
"something in the constitution of the clone (its genotype) which 
tends toward the production of a mouth of a certain size, with teeth 
of a certain form, arrangement, and number." 

Races or strains have been recognized in almost all intensively 
studied Protozoa. For example, Ujihara (1914) and Dobell and Jepps 
(1918) noticed five races in Entamoeba histolytica on the basis of dif- 
ferences in the size of cysts. Spector (1936) distinguished two races in 
the trophozoite of this amoeba. The large strain was found to be 
pathogenic to kittens, but the small strain was not. Meleney and 
Frye (1933, 1935) and Frye and Meleney (1939) also hold that there 
is a small race in Entamoeba histolytica which has a weak capacity for 
invading the intestinal wall and not pathogenic to man. Sapiro, 
Hakansson and Louttit (1942) similarly notice two races which can 
be distinguished by the diameters of cysts, the division line being 
10/x and 9m in living and balsam-mounted specimens respectively. 
The race with large cysts gives rise to trophozoites which are more 
actively motile, ingest erythrocytes, and culture easily, is patho- 
genic to man and kitten, while the race with small cysts develops 
into less actively motile amoebae which do not ingest erythrocytes 
and are difficult to culture, is not pathogenic to hosts, thus not being 
histozoic. It is interesting to note, however, that Cleveland and 
Sanders (1930) found the diameter of the cysts produced in a pure- 
line culture of this sarcodinan, which had originated in a single cyst, 
varied from 7 to 23m- Furthermore, the small race of Frye and 
Meleney mentioned above was later found by Meleney and Zucker- 
man (1948) to give rise to larger forms in culture, which led the last 
two observers to consider that the size range of the strains of this 
amoeba is a characteristic which may change from small to large or 
vice versa under different environmental conditions. 

Investigations by Boyd and his co-workers and others show that 
the species of Plasmodium appear to be composed of many strains 
which vary in diverse physiological characters. In an extended study 
on Trypanosoma lewisi, Taliaferro (1921-1926) found that this flagel- 
late multiplies only during the first ten days in the blood of a rat after 
inoculation, after which the organisms do not reproduce. In the adult 
trypanosomes, the variability for total length in a population is about 
3 per cent. Inoculation of the same pure line into different rats some- 
times brings about small but significant differences in the mean size 
and passage through a rat-flea generally results in a significant vari- 


ability of the pure line. It is considered that some differences in 
dimensions among strains are apparently due to environment (host), 
but others cannot be considered as due to this cause, since they per- 
sist when several strains showing such differences are inoculated 
into the same host. The two strains of T. cruzi isolated from human 
hosts and maintained for 28 and 41 months by Hauschka (1949), 
showed well defined and constant strain-specific levels of virulence, 
different degrees of affinity for certain host tissues, unequal suscepti- 
bility to the quinoline-derivative Bayer 7602, and a difference in re- 
sponse to environmental temperature. The five strains of Tricho- 
monas gallinae studied by Stabler (1948) were found to possess a 
marked variation in virulence to its hosts. 

According to Kidder and his associates, the six strains (H, E, T, 
T-P, W, GHH) of Tetrahymena pyriformis and the two strains (V, 
PP) of T. vorax differ in biochemical reactions. They found the ap- 
pearance of a biochemical variation between a parent strain (T) and 
a daughter strain (T-P) during a few years of separation and a 
greater difference in the reactions between the two species than that 
between the strains of each species. These strains show further dif- 
ferences in antigenic relationships. Five strains of pyriformis con- 
tain qualitatively identical antigens, but differ quantitatively with 
respect to amount, concentration or distribution of antigenic ma- 
terials. The sixth strain (T) contains all the antigens of the other five 
strains and additional antigens. The two strains of vorax are said to 
be nearly identical antigenically. The antigenic differences between 
the two species were marked, since there is no cross-reaction within 
the standard testing time. In these cases, thus, some aspects of the 
physiological difference among different strains are understood. 

Jollos (1921) subjected Paramecium caudatum to various environ- 
mental influences such as temperature and chemicals, and found that 
the animals develop tolerance which is inherited through many gen- 
erations even after removal to the original environment. For exam- 
ple, one of the clones which tolerated only 1.1% of standard solution 
of arsenic acid, was cultivated in gradually increasing concentrations 
for four months, at the end of which the tolerance for this chemical 
was raised to 5%. After being removed to water without arsenic 
acid, the tolerance changed as follows: 22 days, 5%; 46 days, 4.5%; 
151 days, 4%; 166 days, 3%; 183 days, 2.5%; 198 days, 1.25% and 
255 days, 1%. As the organisms reproduced about once a day, the 
acquired increased tolerance to arsenic was inherited for about 250 

There are also known inherited changes in form and structure 


which are produced under the influence of certain environmental 
conditions. Jollos designated these changes long-lasting modifica- 
tions (Dauermodifikationen) and maintained that a change in en- 
vironmental conditions, if applied gradually, brings about a change, 
not in the nucleus, but in the cytoplasm, of the organism which 
when transferred to the original environment, is inherited for a 
number of generations. These modifications are lost usually during 
sexual processes at which time the whole organism is reorganized. 

The long-lasting morphological and physiological modifications 
induced by chemical substances have long been known in parasitic 
Protozoa. Werbitzki (1910) discovered that Trypanosoma brucei 
loses its blepharoplast when inoculated into mice which have 
been treated with pyronin, acridin, oxazin and allied dyes, and 
Piekarski (1949) showed that trypaflavin and organic metal com- 
pounds which act as nuclear poisons and interfere with nuclear di- 
vision, also bring about the loss of blepharoplast in this trypano- 
some. Laveran and Roudsky (1911) found that the dyes mentioned 
above have a special affinity for, and bring about the destruction 
by auto-oxidation of, the blepharoplast. Such trypanosomes lacking 
a blepharoplast behave normally and remain in that condition during 
many passages through mice. When subjected to small doses of cer- 
tain drugs repeatedly, species of Trypanosoma often develop into 
drug-fast or drug-resistant strains which resist doses of the drug 
greater than those used for the treatment of the disease for which 
they are responsible. These modifications may also persist for several 
hundred passages through host animals and invertebrate vectors, 
but are eventually lost. 

Long-lasting modifications have also been produced by several 
investigators by subjecting Protozoa to various environmental in- 
fluences during the nuclear reorganization at the time of fission, 
conjugation, or autogamy. In Stentor (Popoff) and Glaucoma 
(Chatton), long-lasting modifications appeared during asexual divi- 
sions. Calkins (1924) observed a double-type Uroleptus mobilis (Fig. 
95, b) which was formed by a complete fusion of two conjugants. 
This abnormal animal underwent fission 367 times for 405 days, but 
finally reverted back to normal forms, without reversion to double 
form. The double animal of Euplotes patella (d) is, according to Kim- 
ball (1941) and Powers (1943), said to be formed by incomplete di- 
vision and rarely through conjugation. De Garis (1930) produced 
double animals in Paramecium caudatum through inhibition of di- 
vision by exposing the animals to cyanide vapor or to low tempera- 



Jennings (1941) outlined five types of long-lasting inherited 
changes during vegetative reproduction, as follows: (1) changes that 
occur in the course of normal life history, immaturity to sexual ma- 
turity which involves many generations; (2) degenerative changes 
resulting from existence under unfavorable conditions; (3) adaptive 
changes or inherited acclimitization or immunity; (4) changes which 
are neither adaptive nor degenerative, occurring under specific en- 
vironmental conditions; and (5) changes in form, size, and other 
characters, which are apparently not due to environment. 

Whatever exact mechanism by which the long-lasting modifica- 

Fig. 95. a-c, Uroleptus mobilis (Calkins) (a, a pair in conjugation; b, 
an individual from the third generation by division of a double organism 
which had been formed by the coalescence of a conjugating pair; c, a 
product of reversion); d, a double animal of Euplotes patella (Kimball). 

tions are brought about may be, they are difficult to distinguish 
from permanent modification or mutation, since they persist for 
hundreds of generations, and cases of mutation have in most instan- 
ces not been followed by sufficiently long enough pure-line cultures 
to definitely establish them as such (Jollos, 1934; Moewus, 1934; 
Sonneborn, 1947). 

Jollos observed that if Paramecium were subjected to environ- 
mental change during late stages of conjugation, certain individuals, 
if not all, become permanently changed. Possibly the recombining and 
reorganizing nuclear materials are affected in such a way that the 
hereditary constitution or genotype becomes altered. MacDougall 
subjected Chilodonella uncinata to ultraviolet rays and produced 
many changes which were placed in three groups: (1) abnormalities 
which caused the death of the organism; (2) temporary variations 
which disappeared by the third generation ; and (3) variations which 



were inherited through successive generations and hence considered 
as mutations. The mutants were triploid, tetraploid, and tailed 
diploid forms (Fig. 96), which bred true for a variable length of time 
in pure-line cultures, either being lost or dying off finally. The tailed 
form differed from the normal form in the body shape, in the number 
of ciliary rows and contractile vacuoles, and in the mode of move- 
ment, but during conjugation it showed the diploid number of chro- 
mosomes as in the typical form. The tailed mutant remained true 
and underwent 20 conjugations during ten months. 

Fig. 96. Chilodonella uncinata (MacDougall). a, b, ventral and side 
view of normal individual; c, d, ventral and side view of the tailed mutant. 

Kimball (1950) exposed Paramecium aurelia to beta particles from 
plaques containing P 32 and obtained many clones which multiplied 
more slowly than normal animals or died, which conditions were 
interpreted by him to be due to mutational changes induced in the 
micronuclei by the radiation. Kimball found that the radiation was 
less effective if given just before the cytoplasmic division than if 
given at other times during the division interval and that exposure 
of the organisms to ultraviolet ray of wave length 2537 A inactivates 
the Kappa (p. 239). 

The loss of the blepharoplast in trypanosomes mentioned above 
occurs also spontaneously in nature. A strain of Trypanosoma evansi 
which had been maintained in laboratory animals for five years, sud- 
denly lost the blepharoplast (Wenyon, 1928) which condition re- 
mained for 12| years (Hoare, 1940). Hoare and Bennett (1937) found 
five camels out of 100 they examined infected by the same species 
of trypanosome that was without a blepharoplast. One strain inocu- 
lated into laboratory animals has retained this peculiarity for nearly 


three years. Nothing is known as to how such strains arise, though 
some workers suggest mutational change. 

In sexual reproduction, the nuclei of two individuals participate 
in producing new combinations which would naturally bring about 
diverse genetic constitutions. The new combination is accomplished 
either by sexual fusion in Sarcodina, Mastigophora, and Sporozoa, 
or by conjugation in Euciliata and Suctoria. 

The genetics of sexual fusion is only known in a few forms. Perhaps 
the most complete information was obtained by Moewus through 
his extended studies of certain Phytomonadina. In Polytoma (p. 
281), Chlamydomonas (p. 276), and allied forms, the motile indi- 
viduals are usually haploid. Two such individuals (gametes) fuse 
with each other and produce a diploid zygote which encysts. The 
zygote later undergoes at least two divisions within the cyst wall, in 
the first division of which chromosome reduction takes place. These 
swarmers when set free become trophozoites and multiply asexually 
by division for many generations, the descendants of each s warmer 
giving rise to a clone. 

Moewus (1935) demonstrated the segregation and independent as- 
sortment of factors by hybridization of Polytoma. He used two va- 
rieties each of two species: P. uvella and P. pascheri, both of which 
possess 8 haploid chromosomes. Their constitutions were as follows: 

P. uvella 

Form A: Oval (F), without papilla (p), with stigma (S), large (D) 

(Fig. 97, a). 
Form B: Oval (F), without papilla (p), without stigma (s), large (D) 

(Fig. 97, b). 

P. pascheri 

Form C: Pyriform (f), with papilla (P), without stigma (s), large 

(D) (Fig. 97, c). 
Form D: Pyriform (f), with papilla (P), without stigma (s), small 

(d) (Fig. 97, d). 

Thus six different crosses were possible from the four pairs of 
characters. When A (FpSD) and B (FpsD) fuse, the zygote divides 
into four swarmers, two swarmers have stigma (S), and the other 
two lack this cell organ, which indicates the occurrence of segrega- 
tion of the two characters (S, s) during the reduction division. When 
B (FpsD) is crossed with C (fPsD), thus differing in two pairs of 
characters, two swarmers possess one combination or type and the 
other two another combination. Different pairs of combinations are 


of course found. It was found that about half the zygotes gives rise to 
the two parental combinations (Fig. 97, b, c), while the other half 
gives rise to FPsD (e) and fpsD (/). 

When B (FpsD) is crossed with D (fPsd) or A (FpSD) is crossed 
with D (fPsd), only two types of swarmers are also formed from 
each zygote, and in the case of BxD, eight different combinations 
are produced, while in the case of AXD, sixteen different combina- 
tions, which appear in about equal numbers, are formed. Thus these 
four factors or characters show independent assortment during divi- 
sions of the zygote. 

a b c d e ( 

Fig. 97. a, b. Polytoma uvella. a, Form A; b, P^orm B. 
c, d. P. pascheri. c, Form C; d, Form D. 
e, f. Crosses between Forms B and C. (Moewus) 

Furthermore, Moewus noticed that certain other characters ap- 
peared to be linked with some of the four characters mentioned 
above. For example, the length of flagella, if it is under control of a 
factor, is linked on the same chromosome with the size-controlling 
factors (D, d), for large individuals have invariably long flagella 
and small individuals short flagella. During the experiments to de- 
termine this linkage, it was found that crossing over occurs between 
two entire chromosomes that are undergoing synapsis. 

In certain races of Polytoma pascheri and Chlamydomonas euga- 
metos, the sexual fusion takes place between members of different 
clones only. The zygote gives rise as was stated before to four swarm- 
ers by two divisions, which are evenly divided between the two 
sexes, which shows that the sex-determining factors are lodged in a 
single chromosome pair. In a cross between Chlamydomonas para- 
doxa and C. pseudoparadoxa, both of which produce only one type of 
gamete in a clone, the majority of the zygotes yield four clones, two 


producing male gametes and the other two female gametes; but a 
small number of zygotes gives rise to four clones which contain both 
gametes. It is considered that this is due to crossing-over that 
brought the two sex factors (P and M) together into one chromo- 
some, and hence the "mixed" condition, while the other chromosome 
which is devoid of the sex factors gives rise to individuals that soon 

In crosses between Chlamydo?no?ias eugametos which possesses a 
stigma and 10 haploid chromosomes and C. paupera which lacks a 
stigma and 10 haploid chromosomes, 12 pairs of factors including 
sex factor are distinguishable. Consequently at least two chromo- 
somes must have two factors in them. Thus adaptation to acid or 
alkaline culture media was found to be linked with differences in 
the number of divisions in zygote. That there occurs a sex-linked in- 
heritance in Chlamydomonas was demonstrated by crossing stigma- 
bearing C. eugametos of one sex with stigma-lacking C. paupera of 
the opposite sex. The progeny that were of the same sex as C. euga- 
metos parent possessed stigma, while those that were of the same sex 
as C. paupera parent lacked stigma. Thus it is seen that the sex factor 
and stigma factor are located in the same chromosome. 

The genetics of conjugation which takes place between two diploid 
conjugants has been studied by various investigators. Pure-line 
cultures of exconjugants show that conjugation brings about diverse 
inherited constitutions in the clones characterized by difference in 
size, form, division-rate, mortality-rate, vigor, resistance, etc. The 
discovery of mating types in Paramecium and in Euplotes, and in- 
tensive studies of conjugation and related phenomena, are bringing 
to light hitherto unknown information on some of the fundamental 
problems in genetics. 

Sonneborn (1939) has made extended studies of variety 1 of 
Paramecium aurelia (p. 194) and found that genetically diverse ma- 
terials show different types of inheritance, as follows: 

(1) Stocks containing two mating types. When types I and II 
conjugate, among a set of exconjugants some produce all of one 
mating type, others all of the other mating type and still others 
both types (one of one type and the other of the other type). In the 
last mentioned exconjugants, the types segregate usually at the 
first division, since of the two individuals produced by the first divi- 
sion, one and all its progeny, are of one mating type, and the other 
and all its progeny are of the other mating type. A similar change 
was also found to take place at autogamy. Sonneborn therefore con- 
siders that the mating types are determined by macronuclei, as 


judged by segregation at first or sometimes second division in excon- 
jugants and by the influence of temperature during conjugation and 
the first division. 

(2) Stocks containing only one mating type. No conjugation oc- 
curs in such stocks. Autogamy does not produce any change in type 
which is always type I. Stocks that contain type II only have not 
yet been found. 

(3) Hybrids between stocks containing one and two mating types. 
When the members of the stock containing both types I and II 
(two-type condition) conjugate with those of the stock containing 
one type (one-type condition), all the descendants of the hybrid 
exconjugants show two-type condition, which shows the dominancy 
of two-type condition over one-type condition. The factor for the 
two-type condition may be designated A and that for the one-type 
condition a. The parent stocks are AA and aa, and all Fi hybrids Aa. 
When the hybrids (Aa) are backcrossed to recessive parent (aa) 
(158 conjugating pairs in one experiment), approximately one-half 
(81) of the pairs give rise to two-type condition (Aa) and the remain- 
ing one-half (77) of the pairs to one-type condition (aa), thus showing 
a typical Mendelian result. When Fi hybrids (Aa) were interbred by 
120 conjugating pairs, each exconjugant in 88 of the pairs gave 
rise to two- type condition and each exconjugant in 32 pairs pro- 
duced one-type condition, thus approximating an expected Men- 
delian ratio of 3 dominants to 1 recessive. That the F 2 dominants 
are composed of two-thirds heterozygotes (Aa) and one-third homo- 
zygotes (AA) was confirmed by the results obtained by allowing F 2 
dominants to conjugate with the recessive parent stock (aa). Of 19 
pairs of conjugants, 6 pairs gave rise to only dominant progenj^, 
which shows that they were homozygous (AA) and their progeny 
heterozygous (Aa), while 13 pairs produced one-half dominants and 
one-half recessives, which indicates that they were heterozygous 
(Aa) and their progeny half homozygous (aa) and half heterozygous 
(Aa). Thus the genie agreement between two conjugants of a pair 
and the relative frequency of various gene combinations as shown in 
these experiments confirm definitely the occurrence of meiosis and 
chromosomal exchange during conjugation which have hitherto been 
considered only on cytological ground. 

In Euplotes patella, Kimball (1942) made various matings with 
respect to the inheritance of the mating type. The results obtained 
can be explained if it is assumed that mating types I, II, and V, are 
determined by different heterozygous combinations of three allelic 
genes which if homozygous determine mating types III, IV, and VI. 


Upon this supposition, type I has one allele in common with type II, 
and this allele is homozygous in type IV. It has one allele in common 
with type V, and this allele is homozygous in type VI. Type II has 
one allele in common with type V and this is homozygous in type 
III. These alleles were designated by Kimball, mt 1 , mt 2 , and mt 3 . 
The genotypes of the six mating types may be indicated as follows: 
imVmtMI), rn^mt 3 (II), mt 3 mt 3 (III), mtfmt 1 (IV), mt 2 mt 3 (V), and 
mt 2 mt 2 (VI). 

There is no dominance among these alleles, the three heterozygous 
combinations determining three mating types being different from 
one another and from the three determined by homozygous combi- 
nation. Kimball (1939, 1941) had shown that the fluid obtained free 
of Euplotes from a culture of one mating type will induce conjuga- 
tion among animals of certain other mating types. When all possible 
combinations of fluids and animals are made, it was found that the 
fluid from any of the heterozygous types induces conjugation among 
animals of any types other than its own and the fluid from any of 
the homozygous types induces conjugation only among animals of 
the types which do not have the same allele as the type from 
which the fluid came. These reactions may be explained by an 
assumption that each of the mating type alleles is responsible for 
the production by the animal of a specific conjugation-inducing 
substance. Thus the two alleles in a heterozygote act independently 
of each other; each brings about the production by the animal of a 
substance of its own. Thus heterozygous animals are induced to con- 
jugate only by the fluids from individuals which possess an allele 
not present in the heterozygotes. 

The double animals of Euplotes patella (p. 228) conjugate with 
double animals or with single animals in appropriate mixtures and at 
times a double animal gives rise by binary fission to a double and 
two single animals instead of two animals (Fig. 98). Powers (1943) 
obtained doubles of various genotypes for mating types which were 
determined by observing the mating type of each of the two singles 
that arose from the doubles. Doubles of type IV (m^mt 1 ) with a 
single micronucleus (Fig. 98, a) were mated with singles of type VI 
(mt 2 mt 2 ) (6). The double exconjugants (d) were "split" into their 
component singles belonging to mating types IV and VI (g), while 
the doubles were type I (/) . Thus it was found that the phenotype of 
a double animal with separate nuclei was the same as though the 
alleles present in the nuclei were located within one nucleus. The 
fact that loss of one micronucleus had no effect on the type of 
doubles, tends to show that the micronucleus has no direct effect on 



mating types. Sonneborn's view (p. 233) that the macro-nucleus is 
the determiner of the mating types in Paramecium aurelia appears to 
hold true in Euplotes also. 

The relation between the cytoplasm and nucleus in respect to in- 
heritance has become better known in recent years in some ciliates. 
Sonneborn (1934) crossed two clones of Paramecium aurelia differing 
markedly in size and division rate, and found the difference persisted 

Type VI 

Type J 

Type I 

Type I 

Type VI 

Fig. 98. Diagram showing conjugation between a double (type IV) 
and a single (type VI) of Euplotes patella (Powers), a, a double organism 
with one micronucleus (genotype mt'mt 1 ); b, a normal single with a mi- 
cronucleus (genotype mt 2 mt 2 ); c, conjugation of the single with the ami- 
cronucleate half of the double (one of the pronuclei produced in the sin- 
gle migrates into the double, while the two pronuclei of the double un- 
dergo autogamy); d, the exconjugant double is shown to be type I 
(mtmit 2 ); e, exconjugant single remains type VI; f, the double divides 
into two type I doubles; g, occasionally the anterior half of the double 
is widely "split," and division produces a double and two singles, the 
latter testing as type IV and type VI; h, line of exconjugant single. Newly 
formed macronuclei are stippled. 


for a time between the two Fi clones produced from the two mem- 
bers of each hybrid pair of exconjugants, but later both clones be- 
came practically identical in size and division rate (Sonneborn, 
1947). De Garis (1935) succeeded in bringing about conjugation in 
Paramecium caudatum, between the members of a large clone (198m 
long) (Fig. 99, a) and of a small clone (73ju long) (b). The excon- 
jugants of a pair are different only in the cytoplasm as the nuclei are 
alike through exchange of a haploid set of chromosomes. The two 
exconjugants divide and give rise to progeny which grow to size 
characteristic of each parent clone, division continuing at the rate of 
once or twice a day. However, as division is repeated, the descend- 



Fig. 99. Diagram showing the size changes in two clones derived from 
a pair of conjugants of Paramecium caudatum, differing in size (a, b). 
Gradual change in dimensions in each clone during 22 days resulted in 
intermediate size (Jennings) . 

ants of the large clone become gradually smaller after successive 
fissions, while the descendants of the small clone become gradually 
larger, until at the end of 22 days (in one experiment) both clones 
produced individuals of intermediate size (about 135ju long) which 
remained in the generations that followed. Since the exconjugants 
differed in the cytoplasm only, it must be considered probable that 
at first the cytoplasmic character was inherited through several 
vegetative divisions, but ultimately the influence of the new nucleus 
gradually changed the cytoplasmic character. The ultimate size be- 
tween the two clones is however not always midway between the 
mean sizes of the two parent clones, and is apparently dependent 
upon the nuclear combinations brought about by conjugation. It 
has also become known that different pairs of conjugants between 
the same two clones give rise to diverse progeny, similar to those of 
sexual reproduction in Metazoa, which indicates that clones of Para- 


mecium caudatum are in many cases heterozygous for size factors and 
recombination of factors occurs at the time of conjugation. 

In P. aurelia, Kimball (1939) observed that there occasionally 
occurs a change of one mating type into another following autogamy. 
When the change is from type II to type I, not all animals change 
type immediately. Following the first few divisions of the product of 
the first division after autogamy there are present still some type II 
animals, although ultimately all become transformed into type I. 
Here also the cytoplasmic influence persists and is inherited through 
vegetative divisions. Jennings (1941) in his excellent review writes: 
"The primary source of diversities in inherited characters lies in the 
nucleus. But the nucleus by known material interchanges im- 
presses its constitution on the cytoplasm. The cytoplasm retains the 
constitution so impressed for a considerable length of time, dur- 
ing which it assimilates and reproduces true to its impressed char- 
acter. It may do this after removal from contact with the nucleus to 
which its present constitution is due, and even for a time in the 
presence of another nucleus of different constitution. During this 
period, cytoplasmic inheritance may occur in vegetative reproduc- 
tion. The new cells produced show the characteristics due to this 
cytoplasmic constitution impressed earlier by a nucleus that is no 
longer present. But in time the new nucleus asserts itself, impressing 
its own constitution on the cytoplasm. Such cycles are repeated as 
often as the nucleus is changed by conjugation." 

Since the first demonstration some forty years ago of "cytoplas- 
mic inheritance" in higher plants, many cytoplasmic factors have 
been observed in various plants (Michaelis and Michaelis, 1948). 
Information on similar phenomena in Metazoa and Protozoa is of 
recent origin. 

As was already mentioned (p. 196), Sonneborn found in four races 
of variety 4 of Paramecium aurelia a pair of characters which he 
designated as "killer" and "sensitive." The killers liberate para- 
mecin, a desoxyribonucleoprotein (Wagtendonk and Zill, 1947), into 
the culture fluid, to which they are resistant. When the sensitive 
races are exposed to paramecin in the fluid in which the killer race 51 
lived, they show after hours a hump on the oral surface toward the 
posterior end which becomes enlarged, while the anterior part of the 
body gradually wastes away. The body becomes smaller and 
rounded; finally the organisms perish (Fig. 100). Sensitives can be 
mated to the killers, however, without injury if proper precaution is 
taken, since paramecin does not affect them during conjugation. The 
two exconjugants obtain identical genotypes, but their progeny 


are different; that is, one is a killer and the other is a sensitive 
culture. F 2 progeny obtained by selfing show no segregation. There- 
fore, the difference between the killer and the sensitive is due to a 
cytoplasmic difference and not to a genie difference. 

The same observer noted that the thin cytoplasmic paroral strand 
which appears between conjugating pair that ordinarily breaks off 
within a minute, occasionally may remain for a long time, and if the 
strand persists as long as 30 minutes, there occurs an interchange of 
cytoplasm between the pair (Fig. 101). When this happens, both 
exconjugants produce killer clones. In F 2 no segregation takes place. 
Thus killers can introduce the killer trait to sensitives through a 
cytoplasmic connection between them. Sonneborn supposed that the 
killers contain a cytoplasmic genie factor or a plasmagene which de- 

Fig. 100. Paramecium aurelia. The changes leading up to death when the 
sensitives are exposed to the killer stock 51 (variety 4) (Sonneborn). 

termines the killer trait and called it kappa. Preer (1948) demon- 
strated that this kappa is a particle which can be recognized in 
Giemsa-stained specimens (Fig. 102). It was further found that kill- 
ers can be irreversibly transformed into hereditary sensitives by 
eliminating kappa particles by exposure to high temperature (Sonne- 
born, 1946), x-irradiation (Preer, 1948b) or nitrogen mustard (Geck- 
ler, 1949) and that sensitives can be transformed to hereditary killers 
by placing them in concentrated suspensions of broken bodies of 
killers (Sonneborn, 1948a). Therefore, it became clear that kappa is a 
self-multiplying cytoplasmic body which is produced when some are 
already present. 

Killer races of variety 2 differ from each other and from that of 
variety 4 mentioned above, in the effects produced on sensitives be- 
fore the latter are killed. These sensitives possess a gene different 
from that of the killers and cannot be changed into killers by im- 
mersing it to kappa suspensions of broken bodies of killers. When 
this sensitive is mated with a killer, F 2 generation produced by self- 



ing among the killer Fi clones, shows segregation of sensitives and 
killers in the ratio of a single gene difference. In the presence of 
dominant gene K, kappa is maintained, but in recessive k homozy- 
gotes, kappa cannot be maintained and any kappa carried over from 
killers is rapidly lost. Thus it is evident, Sonneborn points out, that 
the plasmagene kappa is dependent on gene K. 

Dipell (1948, 1950) found a number of killer mutants in variety 4. 

End oi- conjuqa+iorv.: Separated except at paroral cone. 
Time until separation is completed 

More +h<m 
3o min. 

KHIer Killer 
Clone, clone 

kk+/c kk+a: 

Killer Sensitive 

e clone 
KK+/C KK+* 

Killer Sensitive 
clone clone 

Fig. 101. Diagram showing the effects of transfers of different amounts 
of the cytoplasm between mates in conjugation of KK+ kappa killers 
and KK sensitives in Paramecium aurelia (Sonneborn). 

She showed through breeding analysis that these mutations have 
brought about no change in any gene affecting kappa or the killer 
trait, but have been in every case due to changes in kappa. In a 
mutant which was capable of producing two types of killing, there 
were two kinds of kappa which she succeeded in separating in differ- 
ent animals and their progeny. Thus it became apparent that kappa 
can undergo mutation, that various mutant kappas can multiply in 
animals with the original genome, and that the kappas are deter- 
mined by themselves and not by nuclear genes. 

According to Preer (1948), the kappa particles (Fig. 102) in the 
killer race G are about 0.4ju long, and those in a mutant Gml only 
about 0.2-0.3ju long, while in other strains they measure as much as 



0.8/* in length. Preer (1948a, 1950) further observed that the kappa 
particles contain desoxyribonucleic acid and vary in form (rod-like or 
spherical), size and number in different races of killers, and that an 
increase, reduction or destructon of the kappas, as determined by 
indirect methods, was correlated with the observed number of the 

Fig. 102. Photomicrographs of Paramecium, aurelia, stained with 
Giemsa's stain (Sonneborn). a, a killer with a number of kappa particles 
in the cytoplasm; b, a sensitive without kappa particles, a few dark- 
stained bodies near the posterior end being bacteria in a food vacuole. 

stained particles. As to the suggestion that the kappa particles may 
be viruses, symbionts (Altenberg, 1948), etc., the reader is referred 
to Sonneborn (1946, 1950). 

The application of antigen-antibody reactions to free-living Pro- 
tozoa began some forty years ago. Bernheimer and Harrison (1940, 
1941) pointed out the antigenic dissimilarity of three species of 
Paramecium in which the members of a clone differ widely in their 


susceptibility to the immobilizing action of a given serum. Strains of 
Tetrahymena pyriformis differ in antigenic reactions, as has already 
been mentioned (p. 227). Sonneborn and his co-workers have studied 
serological reactions in Paramecium aurelia (Sonneborn, 1950). 

When a rabbit is inoculated intraperitoneally with a large number 
of a strain of P. aurelia, its serum immobilizes in a high dilution, the 
organisms of the same strain, but not of other strains. Such a sero- 
logically distinct strain is called a serotype or antigenic type. It was 
found that a clone originating in a homozygous individual gives 
rise to a series of various serotypes. Race 51 gave rise to eight sero- 
types: A, B, C, D, E, G, H and J, and race 29, to seven serotypes: 
A, B, C, D, F, H and J. When a serotype is exposed to its antiserum, 
it changes into other types, which course Sonneborn was able to 
control by temperature and other conditions. For example, serotype 
D (stock 29) may be changed by its antiserum to type B at 32°C. 
and to type H at 20°C, types B, F and H are convertible one into the 
other and all other types can be transformed to any of the three ; and 
serotypes A and B (stock 51) are convertible one into the other, and 
other types can be changed to A or B. The antigenic types are in- 
herited, if the cultures are kept at 26°-27°C. with food enough to 
allow one division a day. When induced or spontaneous changes of 
serotype occur, crosses made among different serotypes of the same 
strain reveal no effective gene differences among them ; thus all sero- 
types of a strain possess apparently an identical genie constitution. 
Sonneborn finds serotype A of stock 29 is not exactby the same as the 
type A of stock 51. When these are crossed, it is found that the dif- 
ference between two antigens is controlled by a pair of allelic genes 
of which the 51A-gene is dominant over the 29A-gene. On the basis 
of these observations, it has been concluded that nuclear genes con- 
trol the specificity of the physical basis of cytoplasmic inheritance 
in these antigenic traits, and hereditary transformations of serotype 
are cytoplasmic "mutations" of hitherto unknown type. 

In the inheritance of the killer trait and of serotype, both traits 
are cytoplasmically determined and inherited; hereditary changes 
are brought about by environmental conditions; and the traits are 
dependent for their maintenance upon nuclear genes. However, the 
specific type of killer trait is controlled by the kind of kappa pres- 
ent, not by the genes, while the specific type of A antigen is de- 
termined by the nuclear genes. The transformation of the killer 
to the sensitive is made irreversible, but that of serotypes is not. 
The various types of killer character are not mutually exclusive, 
as different kinds of kappa can coexist in the same organism and 


its progeny, each kind of kappa controlling production of its cor- 
responding kind of paramecin, while in serotype, two kinds of anti- 
gen substances cannot coexist, thus being mutually exclusive. The 
physical basis of the killer trait lies in the visible Feulgen-positive 
kappa particles, while no such particles have so far been found in 
association with the serotype. 


Altenburg, E.: (1948) The role of symbionts and autocatalysts in 
the genetics of the ciliates. Am. Nat., 82:252. 

Bernheimer, A. W. and Harrison, J. A.: (1940) Antigen-anti- 
body reactions in Paramecium: the aurelia group. J. Immunol., 

■ (1941) Antigenic differentiation among strains of 

Paramecium aurelia. Ibid., 41:201. 

Calkins, G. N. : (1925) Uroleptus mobilis. V. J. Exper. Zool., 41 : 191. 

Cleveland, L. R. and Sanders, Elizabeth P.: (1930) Encystation, 
multiple fission without encystment, etc. Arch. Protist., 70: 

De Garis, C. F.: (1930) Genetic results from conjugation of double 
monsters and free individuals of Paramecium caudatum. Anat. 
Rec, 47:393. 

(1930a) Nucleus versus cytoplasm in the heredity of Para- 
mecium caudatum as shown by conjugation of double monsters. 
Ibid., 47:393. 

(1935) Heritable effects of conjugation between free individ- 

uals and double monsters in diverse races of Paramecium. J. 
Exper. Zool., 71:209. 

Dippell, Ruth V.: (1948) Mutation of the killer plasmagene, 
Kappa, in variety 4 of Paramecium aurelia. Am. Nat., 82:43. 

(1950) Mutation of the killer cytoplasmic factor in Parame- 
cium aurelia. Heredity, 4:165. 

Dobell, C. and Jepps, Margaret W.: (1918) A study of the di- 
verse races of Entamoeba histolytica distinguishable from one 
another by the dimensions of their cysts. Parasitology, 10:320. 

Frye, W. W. and Meleney, H. E.: (1938) The pathogenicity of a 
strain of small race Entamoeba histolytica. Am. J. Hyg., 27:580. 

Furgason, W. H.: (1940) The significant cytostomal pattern of the 
"Glaucoma-Colpidium group," and a proposed new genus and 
species, Tetrahymena geleii. Arch. Protist., 94:224. 

Geckler, R, P.: (1949) Nitrogen mustard inactivation of the cyto- 
plasmic factor, kappa, in Paramecium. Science, 110:89. 

Hauschka, T. S.: (1949) Persistence of strain-specific behavior in 
two strains of Trypanosoma cruzi after prolonged transfer 
through inbred mice. J. Parasit., 35:593. 

Hegner, R. W. : (1919) Heredity, variation, and the appearance of 
diversities during the vegetative reproduction of Arcella dentata. 
Genetics, 4:95. 


Hoare, C. A.: (1940) Recent studies on the kinetoplast in relation 

to heritable variation in trypanosomes. J. Roy. Micr. Soc., 60: 

(1943) Biological races in parasitic Protozoa. Biol. Rev., 18: 

and Bennett, S. C. J.: (1937) Morphological and taxonomic 

studies on mammalian trypanosomes. III. Parasitology. 29:43. 
(1939) IV. Ibid., 30:529. 

Jennings, H. S.: (1909) Heredity and variation in the simplest or- 
ganisms. Am. Nat., 43:322. 

(1916) Heredity, variation and the results of selection in the 

uniparental reproduction of Difflugia corona. Genetics, 1 :407. 

(1929) Genetics of the Protozoa. Bibliogr. Genetica, 5:105. 

(1937) Formation, inheritance and variation of the teeth in 

Difflugia corona. J. Exper. Zool., 77:287. 

(1938) Sex reaction types and their interrelations in Para- 
mecium bursaria. I. Proc. Nat. Acad. Sc, 24:112. 

(1939) Genetics of Paramecium bursaria. I. Genetics, 24:202. 

(1941) Inheritance in Protozoa. In: Calkins and Summers' 

(1941) Protozoa in biological research. New York. 

, Raffel, D., Lynch, R. S. and Sonneborn, T. M.: (1932) 

The diverse biotypes produced by conjugation within a clone of 
Paramecium. J. Exper. Zool., 63:363. 

Jollos, V.: (1913) Experimentelle Untersuchungen an Infusorien. 
Biol. Zentralbl., 33:222. 

(1921) Experimentelle Protistenstudien. I. Arch. Protist., 


(1934) Dauermodifikationen und Mutationen bei Proto- 

zoen. Ibid., 83: 197. 
Kidder, G. W., Stuart, C. A., McGann, Virginia G. and Dewey, 
Virginia C.: (1945) Antigenic relationships in the genus Tetra- 
hymena. Physiol. Zool., 18:415. 
Kimball, R. F.: (1939) A delayed change of phenotype following a 
change of genotype in Paramecium aurelia. Genetics, 24:49. 
- (1939a) Mating types in Euplotes. Am. Nat., 73:451. 
(1941) Double animals and amicronucleate animals in Eu- 
plotes patella with particular reference to their conjugation. J. 
Exper. Zool., 86:1. 
(1942) The nature and inheritance of mating types in Eu- 
plotes patella. Genetics, 27:269. 

(1950) The effect of radiations on genetic mechanism of 

Paramecium aurelia. J. Cell. Comp. Physiol., 35 (sup. 1) : 157. 
List, T.: (1913) Ueber die Temperal- und Lokalvariation von 

Ceratium hirundinella, etc. Arch. Hydrobiol., 9:81. 
Meleney, H. E. and Zuckerman, Lucille K.: (1948) Note on a 

strain of small race Entamoeba histolytica which became large 

in culture. Am. J. Hyg., 47:187. 
Michaelis, P. and Michaelis, G.: (1948) Ueber die Konstanz des 

zytoplasmons bei Epilobium. Planta, 35:467. 


Moewus, F.: (1933) Untersuchungen ueber die Variabilitat von 

Chlamydomonaden. Arch. Protist., 80:128. 
(1934) Ueber Dauermodifikation bei Chlamydomonaden. 

Ibid., 83:220. 
(1935) Ueber die Vererbung des Geschlechts bei Polytoma 

pascheri und bei P. uvella. Ztschr. Induk. Abst.-u. Vererb., 69: 


(1936) Faktorenaustausch, insbesondere der Realisatoren 

bei Chlamydomonas-Kreuzungen. Ber. deutsch. Bot. Ges., 54: 

(1938) Vererbung des Geschlechts bei Chlamydomonas eu- 

gametos und verwandten Arten. Biol. Zentralbl., 58:516. 
Piekarski, G.: (1949) Blepharoplast und Trypaflavinwirkung bei 

Trypanosoma brucei. Zentralbl. Bakt., I. Orig., 153:109. 
Powers, E. L.: (1943) The mating types of double animals in Eu- 

plotes patella. Am. Midi. Natur., 30:175. 
Preer, J. R. Jr.: (1948) The killer cytoplasmic factor kappa: its 

rate of reproduction, the number of particles per cell, and its 

size. Am. Nat., 82:35. 
(1948a) Microscopic bodies in the cytoplasm of "killers" 

of Paramecium aurelia and evidence for the identification of 

these bodies with cytoplasmic factor, kappa. Genetics, 33:625. 
(1950) Microscopically visible bodies in the cytoplasm of 

the "killer" strain of Paramecium aurelia. Ibid., 35:344. 

Reynolds, B. D. : (1924) Interactions of protoplasmic masses in rela- 
tion to the study of heredity and environment in Arcella poly- 
pora. Biol. Bull., 46:106. 

Root, F. M.: (1918) Inheritance in the asexual reproduction in 
Centropyxis aculeata. Genetics, 3:173. 

Sapiro, J. J., Hakansson, E. G. and Louttit, C. M.: (1942) The 
occurrence of two significantly distinct races of Entamoeba his- 
tolytica. Am. J. Trop. Med., 22:191. 

Schroder, B.: (1914) Ueber Planktonepibionten. Biol. Zentralbl., 

Sonneborn, T. M. : (1937) Sex, sex inheritance and sex determina- 
tion in Paramecium aurelia. Proc. Nat. Acad. Sc, 23:378. 

(1939) Paramecium aurelia: mating types and groups; etc. 

Am. Nat., 73:390. 

— (1942) Inheritance in ciliate Protozoa. Ibid., 76:46. 

(1943) Gene and cytoplasm. I, II. Proc. Nat. Acad. Sc, 29: 


(1946) Experimental control of the concentration of cyto- 
plasmic genetic factors in Paramecium. Cold Springs Harbor 
Symp. Quant. Biol., 11:236. 

(1947) Recent advances in the genetics of Paramecium and 

Euplotes. Adv. Genetics, 1:263. 

(1948) Introduction to symposium on plasmagenes, genes 

and characters in Paramecium aurelia. Am. Nat., 82:26. 
(1950) The cytoplasm in heredity. Heredity, 4:11. 


and Lynch, R. S.: (1934) Hybridization and segregation in 

Paramecium aurelia. J. Exper. Zool., 67:1. 

Stabler, R. M.: (1948) Variations in virulenec of strains of Tri- 
chomonas gallinae in pigeons. J. Parasit., 34: 147. 

Taliaferro, W. H.: (1926) Variability and inheritance of size in 
Trypanosoma lewisi. J. Exper. Zool., 43:429. 

(1929) The immunology of parasitic infections. New York. 

and Huff, C. G.: (1940) The genetics of the parasitic Proto- 
zoa. Am. A. Adv. Sc. Publ., 12:57. 

Ujihara, K.: (1914) Studien ueber die Amoebendysenterie. Ztschr. 
Hyg., 77:329. 

Wagtendonk, W. J. v. and Zill, L. P.: (1947) Inactivation of 
paramecin ("killer" substance of Paramecium aurelia 51, va- 
riety 4) at different hydrogen-ion concentrations and tempera- 
tures. J. Biol. Chem., 171:595. 

Wenyon, C. M. : (1928) The loss of the parabasal body in trypano- 
somes. Tr. Roy. Soc. Trop. Med. Hyg., 22:85. 

Wesenberg-Lund, C. : (1908) Plankton investigations of the Danish 
lakes. Copenhagen. 


Chapter 7 
Major groups and phylogeny of Protozoa 

THE Protozoa are grouped into two subphyla: Plasmodroma (p. 
254) and Ciliophora (p. 683). The Plasmodroma are more primi- 
tive Protozoa and subdivided into three classes: Mastigophora 
(p. 254), Sarcodina (p. 417), and Sporozoa (p. 526). The Ciliophora 
possess more complex body organizations, and are divided into two 
classes: Ciliata (p. 683) and Suctoria (p. 863). 

In classifying Protozoa, the natural system would be one which is 
based upon the phylogenetic relationships among them in conform- 
ity with the doctrine that the present day organisms have descended 
from primitive ancestral forms through organic evolution. Unlike 
Metazoa, the great majority of Protozoa now existing do not possess 
skeletal structures, which condition also seemingly prevailed among 
their ancestors, and when they die, they disintegrate and leave 
nothing behind. The exceptions are Foraminifera (p. 493) and 
Radiolaria (p. 516) which produce multiform varieties of skeletal 
structures composed of inorganic substances and which are found 
abundantly preserved as fossils in the earliest fossiliferous strata. 
These fossils show clearly that the two classes of Sarcodina were 
already well-differentiated groups at the time of fossilization. The 
sole information the palaeontological record reveals for our reference 
is that the differentiation of the major groups of Protozoa must have 
occurred in an extremely remote period of the earth history. There- 
fore, consideration of phylogeny of Protozoa had to depend ex- 
clusively upon the data obtained through morphological, physio- 
logical, and developmental observations of the present-day forms. 

The older concept which found its advocates until the beginning 
of the present century, holds that the Sarcodina are the most primi- 
tive of Protozoa. It was supposed that at the very beginning of 
the living world, there came into being undifferentiated mass of pro- 
toplasm which later became differentiated into the nucleus and the 
cytoplasm. The Sarcodina represented by amoebae and allied forms 
do not have any further differentiation and lack a definite body 
wall, they are, therefore, able to change body form by forming 
pseudopodia. These pseudopodia are temporary cytoplasmic proc- 
esses and formed or withdrawn freely, even in the more or less 
permanent axopodia. On the other hand, flagella and cilia are per- 
manent cell-organs possessing definite structural plans. Thus from 
the morphological viewpoint, the advocates of this concept main- 



tained that the Sarcodina are the Protozoa which were most closely 
related to ancestral forms and which gave rise to Mastigophora, 
Ciliata, and Sporozoa. 

This concept is however difficult to follow, since it does not agree 
with the general belief that the plant came into existence before the 
animal; namely, holophytic organisms living on inorganic substances 
anteceded holozoic organisms living on organic substances. There- 
fore, from the physiological standpoint the Mastigophora which 
include a vast number of chlorophyll-bearing forms, must be con- 
sidered as more primitive than the holozoic Sarcodina. The class 
Mastigophora is composed of Phytomastigina (chromatophore-bear- 
ing flagellates and closely related colorless forms) and Zoomastigina 
(colorless flagellates). Of the former, Chrysomonadina (p. 256) are 
mostly naked, and are characterized by possession of 1-2 flagella, 
1-2 yellow chromatophores and leucosin. Though holophytic nutri- 
tion is general, many are also able to carry on holozoic nutrition. 
Numerous chrysomonads produce pseudopodia of different types; 
some possess both flagellum and pseudopodia; others such as Chrys- 
amoeba (Fig. 105) may show flagellate and ameoboid forms (Klebs; 
Scherffel); still others, for example, members of Rhizochrysidina 
(p. 267), may lack flagella completely, though retaining the char- 
acteristics of Chrysomonadina. When individuals of Rhizochrysis 
(p. 267) divide, Scherffel (1901) noticed unequal distribution of the 
chromatophore resulted in the formation of colorless and colored 
individuals (Fig. 110, a, b). Pascher (1917) also observed that in the 
colonial chrysomonad, Chrysarachnion (p. 267), the division of 
component individuals produces many in which the chromatophore 
is entirely lacking (Fig. 110, c, d). Thus these chrysomonads which 
lack chromatophores, resemble Sarcodina rather than the parent 

Throughout all groups of Phytomastigina, there occur forms 
which are morphologically alike except the presence or absence of 
chromatophores. For example, Cryptomonas (p. 273) and Chilo- 
monas (p. 273), the two genera of Cryptomonadina, are so mor- 
phologically alike that had it not been for the chromatophore, the 
former can hardly be distinguished from the latter. Other examples 
are Euglena, Astasia, and Khawkinea; Chlorogonium and Hyalo- 
gonium; Chlamydomonas and Polytoma; etc. 

The chromatophores of various Phytomastigina degenerate read- 
ily under experimental conditions. For instance, Zumstein (1900) 
and recently Pringsheim and Hovasse (1948) showed that Euglena 
gracilis loses its green coloration even in light if cultured in fluids 


rich in organic substances; in a culture fluid with a small amount 
of organic substances, the organisms retain green color in light, lose 
it in darkness; and when cultured in a pure inorganic culture fluid, 
the flagellates remain green even in darkness. Therefore, it would 
appear reasonable to consider that the morphologically similar forms 
with or without chromatophores such as are cited above, are closely 
related to each other phylogenetically, that they should be grouped 
together in any scheme of classification, and that the apparent 
heterogeneity among Phytomastigina is due to the natural course of 
events. The newer concept which is at present followed widely is that 
the Mastigophora are the most primitive unicellular animal organ- 

Of Mastigophora, Phytomastigina are to be considered on the 
same ground more primitive than Zoomastigina. According to the 
studies of Pascher, Scherffel and others, Chrysomonadina appear to 
be the nearest to ancestral forms from which other groups of Phyto- 
mastigina arose. Among Zoomastigina, Rhizomastigina possibly 
gave rise to Protomonadina, from which Polymastigina and Hyper- 
mastigina later arose. The last-mentioned group is the most highly 
advanced one of Mastigophora in which an increased number of 
flagella is an outstanding characteristic. 

As to the origin of Sarcodina, many arose undoubtedly from vari- 
ous Zoomastigina, but there are indications that they may have 
evolved directly from Phytomastigina. As was stated already, 
Rhizochrysidina possess no flagella and the chromatophore often de- 
generates or is lost through unequal distribution during division, 
apparently being able to nourish themselves by methods other than 
holophytic nutrition. Such forms may have given rise to Amoebina. 
Some chrysomonads such as Cyrtophora (p. 260) and Palatinella, 
have axopodia, and it may be considered that they are closer to the 
ancestral forms from which Heliozoa arose through stages such as 
shown by Actinomonas (p. 335), Dimorpha (p. 335), and Pteri- 
domonas (p. 335) than any other forms. Another chrysomonad, 
Porochrysis (p. 260), possesses a striking resemblance to Testacea. 
The interesting marine chrysomonad, Chrysothylakion (p. 267) 
that produces a brownish calcareous test from which extrudes an- 
astomosing rhizopodial network, resembling a monothalamous 
foraminiferan, and forms such as Distephanus (p. 267) with siliceous 
skeletons, may depict the ancestral forms of Foraminifera and 
Radiolaria respectively. The flagellate origin of these two groups of 
Sarcodina is also seen in the appearance of flagellated swarmers dur- 
ing their development. The Mycetozoa show also flagellated phase 


during their life cycle, which perhaps suggests their origin in flagel- 
lated organisms. In fact, in the chrysomonad Myxochrysis (p. 261), 
Pascher (1917) finds a multinucleate and chromatophore-bearing 
organism (Fig. 105, e-j) that stands intermediate between Chryso- 
monadina and Mycetozoa. Thus there are a number of morpho- 
logical, developmental, and physiological observations which sug- 
gest the flagellate origin of various Sarcodina. 

The Sporozoa appear to be equally polyphyletic. The Telosporidia 
contain three groups in which flagellated microgametes occur, which 
suggests their derivation from flagellated organisms. Leger and 
Duboscq even considered them to have arisen from Bodonidae (p. 
362) on the basis of flagellar arrangement. Obviously Gregarinida 
are the most primitive of the three groups. The occurrence of such a 
form as Selenococcidium (p. 572), would indicate the gregarine- 
origin of the Coccidia and the members of Haemogregarinidae (p. 
592) suggest the probable origin of the Haemosporidia in the Coc- 
cidia. The Cnidosporidia are characterized by multinucleate tro- 
phozoites and by the spore in which at least one polar capsule with 
a coiled filament occurs. Some consider them as having evolved 
from Mycetozoa-like organisms, because of the similarity in multi- 
nucleate trophozoites, while others compare the polar filament with 
the flagellum. It is interesting to note here that the nematocyst, 
similar to the polar capsule, occurs in certain Dinoflagellata (p. 310) 
independent of flagella. The life cycle of Acnidosporidia is still in- 
completely known, but the group may have differentiated from such 
Sarcodina as Mycetozoa. 

The Ciliata and Suctoria are distinctly separated from the other 
groups. They possess the most complex body organization seen 
among Protozoa. All ciliates possess cilia or cirri which differ from 
flagella essentially only in size. Apparently Protociliata and Eucili- 
ata have different origins, as judged by their morphological and 
physiological differences. It is probable that Protociliata arose from 
forms which gave rise to Hypermastigina. Among Euciliata, one 
finds such forms as Coleps, Urotricha, Plagiocampa, Microregma, 
Trimyema, Anophrys, etc., which have, in addition to numerous 
cilia, a long flagellum-like process at the posterior end, and Ileonema 
that possesses an anterior vibratile flagellum and numerous cilia, 
which also indicates flagellated organisms as their ancestors. It is 
reasonable to assume that Holotricha are the most primitive ciliates 
from which Spirotricha, Chonotricha, and Peritricha evolved. The 
Suctoria are obviously very closely related to Ciliata and most prob- 
ably arose from ciliated ancestors by loss of cilia during adult stage 


and by developing tentacles in some forms from cytostomes as was 
suggested by Collin (Fig. 13). General reference (Franz, 1919; Lwoff, 


Butschli, 0.: (1883-1887) Bronn's Klassen und Ordnungen des 

Thierreichs. 1. 
Doflein, F. and E. Reichenow: (1949) Lehrbuch der Protozoen- 

kunde. 6th ed. 1. 
Franz, V.: (1919) Zur Frage der phylogenetischen Stellung der 

Protisten, besonders der Protozoen. Arch. Protist., 39:263. 
Lwoff, A.: (1951) Biochemistry and physiology of Protozoa. New 

Minchin, E. A.: (1912) Introduction to the study of the Protozoa. 

Pascher, A.: (1912) Ueber Rhizopoden- und Palmellastadien bei 

Flagellaten, etc. Arch. Protist., 25:153. 
(1916) Rhizopodialnetz als Fangvorrichtung bei einer Plas- 

modialen Chrysomonade. Ibid., 37:15. 
(1916a) Fusionsplasmodien bei Flagellaten und ihre Be- 

deutung fiir die Ableitung der Rhizopoden von den Flagellaten. 

Ibid., 37:31. 
(1917) Flagellaten und Rhizopoden in ihren gegenseitigen 

Beziehungen. Ibid., 38:1. 

(1942) Zur Klarung einiger gefarbter und farbloser Flagel- 

laten und ihrer Einrichtungen zur Aufnahme animalischer Nahr- 
ung. Ibid., 96:75. 

Pringsheim, E. G. and Hovasse, R.: (1948) The loss of chromato- 
phores in Euglena gracilis. New Phytologist, 47:52. 

Scherffel, A.: (1901) Kleiner Beitrag zur Phylogenie einiger Grup- 
pen niederer Organismen. Bot. Zeit., 59:143. 

Zumstein, H.: (1900) Zur Morphologie und Physiologie der Eu- 
glena gracilis. Jahrb. wiss. Botanik., 34:149. 

Chapter 8 
Phylum Protozoa Goldfuss 

Subphylum 1 Plasmodroma Doflein 

THE Plasmodroma possess pseudopodia which are used for loco- 
motion and food-getting or flagella that serve for cell-organs of 
locomotion. In Sporozoa, the adult stage does not possess any cell- 
organs of locomotion. The body structure is less complicated than 
that of Ciliophora. In some groups, are found various endo- and 
exo-skeletons. The nucleus is of one kind, but may vary in number. 
All types of nutrition occur. Sexual reproduction is exclusively by 
sexual fusion or automixis; asexual reproduction is by binary or 
multiple fission or budding. The majority are free-living, but numer- 
ous parasitic forms occur, Sporozoa being all parasitic. 

The Plasmodroma are subdivided into three classes as follows: 

Trophozoite with fiagellum Class 1 Mastigophora 

Trophozoite with pseudopodium Class 2 Sarcodina (p. 417) 

Without cell-organs of locomotion; producing spores; all parasitic 

Class 3 Sporozoa (p. 526) 

Class 1 Mastigophora Diesing 

The Mastigophora includes those Protozoa which possess one to 
several flagella. Aside from this common characteristic, this class 
makes a very heterogeneous assemblage and seems to prevent a 
sharp distinction between the Protozoa and the Protophyta, as it 
includes Phytomastigina which are often dealt with by botanists. 

In the majority of Mastigophora, each individual possesses 1-4 
flagella during the vegetative stage, although species of Polymasti- 
gina may possess up to 8 or more flagella and of Hypermastigina a 
greater number of flagella. The palmella stage (Fig. 103) is common 
among the Phytomastigina and the organism is capable in this stage 
not only of metabolic activity and growth, but also of reproduction. 
In this respect, this group shows also a close relationship to algae. 

All three types of nutrition, carried on separately or in combina- 
tion, are to be found among the members of Mastigophora. In holo- 
phytic forms, the chlorophyll is contained in the chromatophores 
which are of various forms among different species and which differ 
in colors, from green to red. The difference in color appears to be due 
to the pigments which envelop the chlorophyll body (p. 89). Many 
forms adapt their mode of nutrition to changed environmental con- 
ditions; for instance, from holophytic to saprozoic in the absence of 
the sunlight. Holozoic, saprozoic and holophytic nutrition are said 



to be combined in such a form as Ochromonas. In association with 
chromatophores, there occurs refractile granules or bodies, the 
pyrenoids, which are connected with starch -form at ion. Reserve 
food substances are starch, oil, etc. (p. 113). 

In less complicated forms, the body is naked except for a slight 
cortical differentiation of the ectoplasm to delimit the body surface 
and is capable of forming pseudopodia. In others, there occurs a thin 
plastic pellicle produced by the cytoplasm, which covers the body 
surface closely. In still others, the body form is constant, being en- 
cased in a shell, test, or lorica, which is composed of chitin, pseudo- 
chitin, or cellulose. Not infrequently a gelatinous secretion envelops 
the body. In three families of Protomonadina there is a collar-like 
structure located at the anterior end, through which the flagellum 

The great majority of Mastigophora possess a single nucleus, and 
only a few are multinucleated. The nucleus is vesicular and contains 
a conspicuous endosome. Contractile vacuoles are always present in 
the forms inhabiting fresh water. In simple forms, the contents of 
the vacuoles are discharged directly through the body surface to 
the exterior; in others there occurs a single contractile vacuole near 
a reservoir which opens to the exterior through the so-called cyto- 
pharynx. In the Dinoflagellata, there are apparently no contractile 
vacuoles, but non-contractile pusules (p. 310) occur in some forms. 
In chromatophore-bearing forms, there occurs usually a stigma 
which is located near the base of the flagellum and seems to be the 
center of phototactic activity of the organism which possesses it. 
Asexual reproduction is, as a rule, by longitudinal fission, but in 
some forms multiple fission also takes place under certain circum- 
stances, and in others budding may take place. Colony-formation 
(p. 174), due to incomplete separation of daughter individuals, is 
widely found among this group. Sexual reproduction has been re- 
ported in a number of species. 

The Mastigophora are free-living or parasitic. The free-living 
forms are found in fresh and salt waters of every description ; many 
are free-swimming, others creep over the surface of submerged ob- 
jects, and still others are sessile. Together with algae, the Mastigoph- 
ora compose a major portion of plankton life which makes the 
foundation for the existence of all higher aquatic organisms. The 
parasitic forms are ecto- or endo-parasitic, and the latter inhabit 
either the digestive tract or the circulatory system of the host ani- 
mal. Trypanosoma, a representative genus of the latter group, in- 
cludes important disease-causing parasites of man and of domestic 


The Mastigophora are divided into two subclasses as follows : 

With chromatophores Subclass 1 Phytomastigina 

Without chromatophores Subclass 2 Zoomastigina (p. 333) 

Subclass 1 Phytomastigina Doflein 

The Phytomastigina possess the chromatophores and their usual 
method of nutrition is holophytic, though some are holozoic, sapro- 
zoic or mixotrophic; the majority are conspicuously colored; some 
that lack chromatophores are included in this group, since their 
structure and development resemble closely those of typical Phyto- 

Some observers consider the types of flagella as one of the char- 
acters in taxonomic consideration (Petersen, 1929; Vlk, 1938: Owen, 
1949; etc.). Owen found, for example, "lash flagella" (with a terminal 
filament) in some species of Phytomonadina, Rhizomastigina, Pro- 
tomonadina and Polymastigina and simple flagella in the forms in- 
cluded in Chrysomonadina, Cryptomonadina, Euglenoidina and 
Dinoflagellata; and simple flagellum and flagella on Oikomonas and 
Monas. He advocated the transfer of the latter two genera from 
Protomonadina to Chrysomonadina. 

1-4 flagella, either directed anteriorly or trailing 
Chromatophores yellow, brown or orange 

Anabolic products fat, leucosin Order 1 Chrysomonadina 

Anabolic products starch or similar carbohydrates 

Order 2 Cryptomonadina (p. 272) 

Chromatophores green 

Anabolic products starch and oil. Order 3 Phytomonadina (p. 276) 

Anabolic products paramylon Order 4 Euglenoidina (p. 293) 

Anabolic products oil Order 5 Chloromonadina (p. 306) 

2 flagella, one of which transverse Order 6 Dinoflagellata (p. 310) 

Order 1 Chrysomonadina Stein 

The chrysomonads are minute organisms and are plastic, since 
the majority lack a definite cell- wall. Chromatophores are yellow to 
brown and usually discoid, though sometimes reticulated, in form. 
Metabolic products are leucosin and fats. 1-2 flagella are inserted at 
or near the anterior end of body where a stigma is present. 

Many chrysomonads are able to form pseudopodia for obtaining 
food materials which vary among different species. Nutrition, though 
chiefly holophytic, is also holozoic or saprozoic. Contractile vacuoles 
are invariably found in freshwater forms, and are ordinarily of 
simple structure. 

Under conditions not fully understood, the chrysomonads lose 


their fiagella and undergo division with development of mucilaginous 
envelope and thus transform themselves often into large bodies 
known as the palmella phase and undertake metabolic activities as 
well as multiplication (Fig. 103). Asexual reproduction is, as a rule, 

m c w 

Qb — 1 

m \ / b 

Fig. 103. The life-cycle of Chromulina, X about 200 (Kiihn). a, encyst- 
ment; b, fission; c, colony-formation; d, palmella-formation. 

by longitudinal division during either the motile or the palmella 
stage. Incomplete separation of the daughter individuals followed 
by repeated fission, results in numerous colonial forms mentioned 
elsewhere (p. 174). Some resemble higher algae very closely. Sexual 
reproduction is unknown in this group. Encystment occurs com- 
monly; the cyst is often enveloped by a silicious wall possessing an 
opening with a plug. Taxonomy (Doflein, 1923; Schiller, 1925a; 
Pascher, 1926; Conrad, 1926; Scherffel, 1926; Hollande, 1952). 

The chrysomonads inhabit both fresh and salt waters, often occur- 
ring abundantly in plankton. 

Motile stage dominant Suborder 1 Euchrysomonadina 

Palmella stage dominant 

Sarcodina-like; flagellate stage unknown 

Suborder 2 Rhizochrysidina (p. 267) 

With flagellate phase Suborder 3 Chrysocapsina (p. 269) 

Suborder 1 Euchrysomonadina Pascher 

With or without simple shell 

One flagellum Family 1 Chromulinidae (p. 258) 

2 flagella 

Fiagella equally long Family 2 Syncryptidae (p. 262) 

Flagella unequally long Family 3 Ochromonadidae (p. 264) 

With calcareous or silicious shell 

Bearing calcareous discs and rods. . . .Family 4 Coccolithidae (p. 266) 
Bearing silicious skeleton Family 5 Silicoflagellidae (p. 267) 


Family 1 Chromulinidae Engler 

Minute forms, naked or with sculptured shell; with a single flagel- 
lum; often with rhizopodia; a few colonial; free-swimming or at- 

Genus Chromulina Cienkowski. Oval; round in cross-section; 
amoeboid; 1-2 chromatophores ; palmella stage often large; in fresh 
water. Numerous species. The presence of a large number of these 
organisms gives a golden-brown color to the surface of the water. 
Development (Doflein, 1923); species (Doflein, 1921, 1922; Schiller, 
1929; Pascher, 1929; Conrad, 1930). 

C. pascheri Hofeneder (Fig. 104, a, b). 15-20/* in diameter. 

Genus Pseudochromulina Doflein. Spheroid body amoeboid; cyto- 
plasm granulated; two contractile vacuoles anterior; a single flagel- 
lum about the body length; a yellow tray-like chromatophore with 
upturned edge; stigma and pyrenoid absent; nucleus central; cyst 
ovoid, with asymmetrical siliceous wall with an aperture tube (Do- 
flein, 1921). 

P. asymmetrica D. Body 3-4 /* in diameter; cytoplasm with fat and 
probably leucosin; cyst 4/* by 3/*; aperture tube about l/i; fresh 
water (Doflein, 1921). 

Genus Chrysamoeba Klebs. Body naked; flagellate stage ovoid, 
with 2 chromatophores, sometimes slender pseudopodia at the same 
time; flagellum may be lost and the organism becomes amoeboid, 
resembling Rhizochrysis (p. 267) ; standing fresh water. 

C. radians K. (Fig. 105, a, b). Flagellated form measures 8/x by 
3.5/*; amoeboid stage about 8-10/* by 3-4/x, with 10-20/x long radiat- 
ing pseudopodia; cyst 7/* in diameter (Doflein, 1922). 

Genus Chrysapsis Pascher. Solitary; plastic or rigid; chromato- 
phore diffused or branching; with stigma; amoeboid movement; 
holophytic, holozoic; fresh water. Several species. 

C. sageneF. (Fig. 104, c). Anterior region actively plastic; stigma 
small; 8-14m long; flagellum about 30/* long. 

Genus Chrysococcus Klebs. Shell spheroidal or ovoidal, smooth 
or sculptured and often brown-colored; through an opening a flagel- 
lum protrudes; 1-2 chromatophores; one of the daughter individuals 
formed by binary fission leaves the parent shell and forms a new one ; 
fresh water. Lackey (1938) found several species in Scioto River, 

C. ornatus Pascher (Fig. 104, d). 14-16/* by 7-10/*. 

Genus Mallomonas Perty (Pseudomallomonas Chodat). Body 
elongated; with silicious scales and often spines; 2 chromatophores 



rod-shaped; fresh water. Numerous species (Pascher, 1921; Conrad, 
1927, 1930). 

M . litomosa Stokes (Fig. 104, e). Scales very delicate, needle-like 
projections at both ends; flagellum as long as body; 24-32/* by 8/x- 

Fig. 104. a, b, Chromulina pascheri, X670 (Hofeneder); c, Chrysapsis 
sagene, X1000 (Pascher); d, Chrysococcus ornatus, X600 (Pascher); e, 
Mallomonas litomosa, X400 (Stokes); f, Pyramidochrysis modesta, X670 
(Pascher); g, Sphaleromantis ochracea, X600 (Pascher); h, Kephyrion 
ovum, X1600 (Pascher); i, Chrysopyzis cyathus, X600 (Pascher); j, 
Cyrtophora pedicellata, X400 (Pascher); k, Palatinella cyrtophora, X400 
(Lauterborn) ; 1, Chrysosphaerella longispina, X600 (Lauterborn). 


Genus Microglena Ehrenberg. Body ovoid to cylindrical; with a 
firm envelope in the surface of which are embedded many lenticular 
masses of silica (Conrad, 1928); a single flagellum at anterior end; a 
reservoir around which four to eight contractile vacuoles occur; a 
sheet-like chromatophore; stigma; leucosin; fresh water. 

M. ovum Conrad (Fig. 106, a). 31-38ju by 18-25m (Conrad, 1928). 

Genus Pyramidochrysis Pascher. Body form constant; pyriform 
with 3 longitudinal ridges; flagellate end drawn out; a single chro- 
matophore; 2 contractile vacuoles; fresh water. 

P. modesta P. (Fig. 104,/). 11-13/z long. 

Genus Sphaleromantis Pascher. Triangular or heart-shaped; 
highly flattened; slightly plastic; 2 chromatophores; 2 contractile 
vacuoles ; stigma large; long flagellum; fresh water. 

S. ochracea P. (Fig. 104, g). 6-13m long. 

Genus Kephyrion Pascher. With oval or fusiform lorica ; body fills 
posterior half of lorica; one chromatophore; a single short flagellum; 
small; fresh water. Species (Conrad, 1930). 

K. ovum P. (Fig. 104, h). Lorica up to 7 p. by 4;u. 

Genus Chrysopyxis Stein. With lorica of various forms, more or 
less flattened; 1-2 chromatophores; a flagellum; attached to algae in 
fresh water. 

C. cyathus Pascher (Fig. 104, i). One chromatophore; flagellum 
twice body length; lorica 20-25^ by 12-15/x. 

Genus Cyrtophora Pascher. Body inverted pyramid with 6-8 
axopodia and a single flagellum; with a contractile stalk; a single 
chromatophore ; a contractile vacuole ; fresh water. 

C. pedicellata P. (Fig. 104, j). Body 18-22julong; axopodia 40-60m 
long; stalk 50-80;u long. 

Genus Palatinella Lauterborn. Lorica tubular; body heartshaped ; 
anterior border with 16-20 axopodia; a single flagellum; a chromato- 
phore; several contractile vacuoles; fresh water. 

P. cyrtophora L. CFig. 104, k). Lorica 80-1 50/z long ; body 20-25/x by 
18-25ju; axopodia 50/x long. 

Genus Chrysosphaerella Lauterborn. In spherical colony, indivi- 
dual cell, oval or pyriform, with 2 chromatophores; imbedded in 
gelatinous mass ; fresh water. 

C. longispina L. (Fig. 104, I). Individuals up to 15^ by 9^; colony 
up to 250ju in diameter; in standing water rich in vegetation. 

Genus Porochrysis Pascher. Shell with several pores through 
which rhizopodia are extended ; a flagellum passes through an apical 
pore; a single small chromatophore; leucosin; a contractile vacuole; 
fresh water. 



P. aspergillus P. (Fig. 105, c, d). Shell about 35m long by 25/z wide; 
chromatophore very small; a large leucosin grain; fresh water. 

Genus Myxochrysis Pascher. Body multinucleate, amoeboid; with 
yellowish moniliform chromatophores, many leucosin granules and 
contractile vacuoles; holozoic; surrounded by a brownish envelop 
which conforms with body form; flagellated swarmers develop into 

Fig. 105. a, flagellate and b, amoeboid phase of Chrysamoeba radians, 
X670 (Klebs); c, surface view and d, optical section of Porochrysis asper- 
gillus, X400 (Pascher); e-j, Myxochrysis paradoxa (Pascher). e, a medium 
large Plasmodium with characteristic envelop; the large food vacuole 
contains protophytan, Scenedesmus, X830; f, diagrammatic side view of a 
Plasmodium, engulfing a diatom; moniliform bodies are yellowish 
chromatophores, X1000; g-i, development of swarmer into Plasmodium 
(stippled bodies are chromatophores), X1200. 

multinucleate Plasmodium; plasmotomy and plasmogamy; fresh 
water (Pascher, 1916a). 

M. paradoxa P. (Fig. 105, e-j). Plasmodium 15-18^ or more in 
diameter; in standing water. 

Genus Angulochrysis Lackey. Body ovoid: colorless, thin lorica 
rounded anteriorly and flattened posteriorly into "wings"; a single 
flagellum long; no cytostome; two bright yellow-brown chromato- 
phores; no stigma; swims with a slow rotation; marine (Lackey, 



A. erratica L. (Fig. 106, b, c). Body up to 12/x long; lorica up to 
30m high; flagellum about four times the body length; Woods Hole. 

Genus Stylochromonas L. Body ovoid, sessile with a stiff stalk: 
with a large collar at anterior end; a single flagellum; two golden 
brown chromatophores; no stigma; marine (Lackey, 1940). 

S. minuta L. (Fig. 106, d). Body 5-8 m long; collar about 6/x high; 
flagellum about twice the body length. 

Fig. 106. a, Microglena ovum, X680 (Conrad); b, c, two views of 
Angulochrysis erratica, X900 (Lackey); d, Stylochromonas minuta, X1200 

Family 2 Syncryptidae Poche 

Solitary or colonial chrysomonads with 2 equal flagella; with or 
without pellicle (when present, often sculptured) ; some possess stalk. 

Genus Syncrypta Ehrenberg. Spherical colonies; individuals with 
2 lateral chromatophores, embedded in a gelatinous mass; 2 con- 
tractile vacuoles ; without stigma ; cysts unknown ; fresh water. 

S. volvox E. (Fig. 107, a). 8-14 M by 7-12/z; colony 20-70m in diam- 
eter; in standing water. 

Genus Synura Ehrenberg (Synuropsis Schiller). Spherical or ellip- 
soidal colony composed of 2-50 ovoid individuals arranged radially; 
body usually covered by short bristles; 2 chromatophores lateral; no 
stigma; asexual reproduction of individuals is by longitudinal di- 
vision; that of colony by bipartition; cysts spherical; fresh water. 
Species (Korshikov, 1929). 

S. uvella E. (Fig. 107, b). Cells oval; bristles conspicuous; 20-40m 
by 8-17^; colony 100-400^ in diameter; if present in large numbers, 



the organism is said to be responsible for an odor of the water re- 
sembling that of ripe cucumber. 

S. adamsi Smith (Fig., 107 c). Spherical colony with individuals 
radiating; individuals long spindle, 42-47/t by 6.5-7// ; 2 flagella up 
to 17// long; in fresh water pond. 

Fig. 107. a, Syncrypta volvox, X430 (Stein); b, Synura uvella, X500 

(Stein); c, S. adamsi, X280 (Smith); d, Hymenomonas roseola, X400 

(Klebs); e, Derepyxis amphora, X540 (Stokes); f, D. ollula, X600 
(Stokes); g, Stylochrysallis parasitica, X430 (Stein). 

Genus Hymenomonas Stein. Solitary; ellipsoid to cylindrical; 
membrane brownish, often sculptured; 2 chromatophores; without 
stigma; a contractile vacuole anterior; fresh water. 

H. roseola S. (Fig. 107, d). 17-50// by 10-20/*. 

Genus Derepyxis Stokes. With cellulose lorica, with or without a 
short stalk; body ellipsoid to spherical with 1-2 chromatophores; 
2 equal flagella; fresh water. 

D. amphora S. (Fig. 107, e). Lorica 25-30// by 9-18//; on algae in 
standing water. 

D. ollula S. (Fig. 107,/). Lorica 20-25// by 15//. 

Genus Stylochrysalis Stein. Body fusiform; with a gelatinous 
stalk attached to Volvocidae; 2 equal flagella; 2 chromatophores; 
without stigma; fresh water. 

S. parasitica S. (Fig. 107, g). Body 9-1 l/i long; stalk about 15/z 
long; on phytomonads. 



Family 3 Ochromonadidae Pascher 

With 2 unequal flagella; no pellicle and plastic; contractile vacu- 
oles simple; with or without a delicate test; solitary or colonial; 
free-swimming or attached. 

Genus Ochromonas Wyssotzki. Solitary or colonial; body surface 
delicate; posterior end often drawn out for attachment; 1-2 chro- 
matophores; usually with a stigma; encystment; fresh water. Many 
species (Doflein, 1921, 1923). 

0. mutdbilis Klebs (Fig. 108, a). Ovoid to spherical; plastic, 15-30m 
by 8-22 M . 

0. ludibunda Pascher (Fig. 108, b). Not plastic; 12-17m by 6— 12ju. 

0. granulans Doflein. No stigma; 5-12/z long (Doflein, 1922). 

Fig. 108. a, Ochromonas mutdbilis, X670 (Senn); b, 0. ludibunda, X540 
(Pascher); c, Uroglena volvox, X430 (Stein); d, Uroglenopsis americana, 
X470 (Lemmermann) ; e, Cyclonexis annularis, X540 (Stokes); f, Dino- 
bryon sertularia, X670 (Scherffel) ; g, Hyalobryon ramosum., X540 (Lauter- 
born); h, Stylopyxis viucicola, X470 (Bolochonzew). 


Genus Uroglena Ehrenberg. Spherical or ovoidal colon}', com- 
posed of ovoid or ellipsoidal individuals arranged on periphery of a 
gelatinous mass; all individuals connected with one another by 
gelatinous processes running inward and meeting at a point; with a 
stigma and a plate-like chromatophore; asexual reproduction of 
individuals by longitudinal fission, that of colony by bipartition; 
cysts spherical with spinous projections, and a long tubular process; 
fresh water. One species. 

U. volvox E. (Fig. 108, c). Cells 12-20/* by 8-13/*; colony 40-400/* 
in diameter; in standing water. 

Genus Uroglenopsis Lemmermann. Similar to Uroglena, but 
individuals without inner connecting processes. 

U. americana (Calkins) (Fig. 108, d). Each cell with one chro- 
matophore; 5-8/* long; flagellum up to 32/* long; colony up to 300/* 
in diameter; when present in abundance, the organism gives an of- 
fensive odor to the water (Calkins). Morphology, development 
(Troitzkaja, 1924). 

U. europaea Pascher. Similar to the last-named species; but 
chromatophores 2; cells up to 7/* long; colon y 150-300/* in diameter. 

Genus Cyclonexis Stokes. Wheel-like colony, composed of 10-20 
wedge-shaped individuals; young colony funnel-shaped; chromato- 
phores 2, lateral; no stigma; reproduction and encystment unknown ; 
fresh water. 

C. annularis S. (Fig. 108, e). Cells 11-14/* long; colony 25-30/* in 
diameter; in marshy water with sphagnum. 

Genus Dinobryon Ehrenberg. Solitary or colonial; individuals 
with vase-like, hyaline, but sometimes, yellowish cellulose test, 
drawn out at its base; elongated and attached to the base of test 
with its attenuated posterior tip; 1-2 lateral chromatophores; 
usually with a stigma; asexual reproduction by binary fission; one 
of the daughter individuals leaving test as a swarmer, to form a new 
one; in colonial forms daughter individuals remain attached to the 
inner margin of aperture of parent tests and there secrete new tests; 
encystment common; the spherical cysts possess a short process; 
Ahlstrom (1937) studied variability of North American species and 
found the organisms occur more commonly in alkaline regions than 
elsewhere; fresh water. Numerous species. 

D. sertularia E. (Fig. 108,/). 23-43/* by 10-14/*. 

D. divergens Imhof. 26-65/* long; great variation in different lo- 

Genus Hyalobryon Lauterborn. Solitary or colonial; individual 
body structure similar to that of Dinobryon; lorica in some cases 



tubular, and those of young individuals are attached to the exterior 
of parent tests ; fresh water. 

H. ramosum L. (Fig. 108, g). Lorica 50-7 0/j long by 5-9 ^ in diame- 
ter; body up to 30/x by 5/x; on vegetation in standing fresh water. 

Genus Stylopyxis Bolochonzew. Solitary; body located at bottom 
of a delicate stalked lorica with a wide aperture ; 2 lateral chromato- 
phores ; fresh water. 

S. mucicolali. (Fig. 108, h). Lorica 17— 18^ long; stalk about 33/x 
long; body 9— llyu long: fresh water. 

Family 4 Coccolithidae Lohmann 

The members of this family occur, with a few exceptions, in salt 
water only; with perforate (tremalith) or imperforate (discolith) 
discs, composed of calcium carbonate; 1-2 flagella; 2 yellowish 

Fig. 109. a, Pontosphaerahaeckeli, X1070 (Kiihn); b, Discosphaeratubi- 
fer, X670 (Klihn); c, Distephanus speculum, X530 (Kiihn); d, Rhizo- 
chrysis scherffeli, X670 (Doflein); e-g, Hy drums foetidus (e, entire 
colony; f, portion; g, cyst), e (Berthold), f, X330, g, X800 (Klebs); h, i, 
Chrysocapsa paludosa, X530 (West); j, k, Phaeosphaera gelatinosa (j, part 
of a mass, X 70 ; k, three cells, X330) (West). 


chromatophores ; a single nucleus; oil drops and leucosin; holophytic. 
Taxonomy and phylogeny (Schiller, 1925, 1926; Conrad, 1928a; 
Kamptner, 1928; Deflandre, 1952a). 

Examples : 

Pontosphaera haeckeli Lohmann (Fig. 109, a). 
Discosphaera tubifer Murray and Blackman (Fig. 109, b). 

Family 5 Silicoflagellidae Borgert 

Exclusively marine planktons; with siliceous skeleton which en- 
velops the body. Example: Distephanus speculum (Miiller) (Fig. 109, 
c) (Deflandre, 1952). 

Suborder 2 Rhizochrysidina Pascher 

No flagellate stage is known to occur; the organism possesses pseu- 
dopodia; highly provisional group, based wholly upon the absence of 
flagella; naked or with test; various forms; in some species chroma- 
tophores are entirely lacking, so that the organisms resemble some 
members of the Sarcodina. Several genera. 

Genus Rhizochrysis Pascher. Body naked and amoeboid ; with 1-2 
chromatophores : fresh water. 

R. scherffeli P. (Figs. 109, d; 110, a, b). 10-14/* in diameter; 1-2 
chromatophores: branching rhizopods; fresh water. 

Genus Chrysidiastrum Lauterborn. Naked; spherical; often sev- 
eral in linear association by pseudopodia; one yellow-brown chro- 
matophore; fresh water. 

C. catenation L. Cells 12-14ju in diameter (Pascher, 1916a). 

Genus Chrysarachnion Pascher. Ameboid organism; with achro- 
matophore, leucosin grain and contractile vacuole; many individuals 
arranged in a plane and connected by extremely fine rhizopods, the 
whole forming a cobweb network. Small animals are trapped by the 
net; chromatophores are small; nutrition both holophytic and holo- 
zoic; during division the chromatophore is often unevenly distrib- 
uted so that many individuals without any chromatophore are 
produced; fresh water (Pascher, 1916a). 

C. insidians P. (Fig. 110, c, d). Highly amoeboid individuals 3-4/x 
in diameter; chromatophore pale yellowish brown, but becomes blu- 
ish green upon death of organisms; a leucosin grain and a contractile 
vacuole; colony made up of 200 or more individuals. 

Genus Chrysothylakion Pascher. With retort-shaped calcareous 
shell with a bent neck and an opening; shell reddish brown (with 



Fig. 110. a, b, Rhizochrysis scherffeli, X500 (Scherffel). a, 4 chroma- 
tophore-bearing individuals and an individual without chromatophore; 
b, the last-mentioned individual after 7 hours, c, d, Chrysarachnion insi- 
dians (Pascher). c, part of a colony composed of individuals with and 
without chromatophore, X1270; d, products of division, one individual 
lacks chromatophore, but with a leucosin body, X2530. e, f, Chrysothy- 
lakion vorax (Pascher). e, an individual with anastomosing rhizopodia and 
"excretion granules," XS70; f, optical section of an individual; the cyto- 
plasm contains two fusiform brownish chromatophores, a spheroid 
nucleus, a large leucosin body and contractile vacuole, X about 1200. 


iron) in old individuals; through the aperture are extruded extremely 
fine anastomosing rhizopods; protoplasm which fills the shell is 
colorless; a single nucleus, two spindle-form brown chromatophores, 
several contractile vacuoles and leucosin body; marine water. 

C. vorax P. (Fig. 110, e, /). The shell measures 14-18/x long, 7-10/x 
broad, and 5-6/x high; on marine algae. 

Suborder 3 Chrysocapsina Pascher 

Palmella stage prominent; flagellate forms transient; colonial; 
individuals enclosed in a gelatinous mass ; 1-2 flagella, one chromato- 
phore, and a contractile vacuole; one group of relatively minute 
forms and the other of large organisms. 

Genus Hydrurus Agardh. In a large (1-30 cm. long) branching 
gelatinous cylindrical mass; cells yellowish brown; spherical to 
ellipsoidal; with a chromatophore; individuals arranged loosely in 
gelatinous matrix; apical growth resembles much higher algae; mul- 
tiplication of individuals results in formation of pyrimidal forms 
with a flagellum, a chromatophore, and a leucosin mass; cyst may 
show a wing-like rim; cold freshwater streams. 

H. foetidus Kirschner (Figs. 32, d-f; 109, e-g). Olive-green, feath- 
ery tufts, 1-30 cm. long, develops an offensive odor; sticky to touch; 
occasionally encrusted with calcium carbonate; in running fresh 

Genus Chrysocapsa Pascher. In a spherical to ellipsoidal gelati- 
nous mass; cells spherical to ellipsoid; 1-2 chromatophores; with or 
without stigma ; freshwater. 

C. paludosa P. (Fig. 109, h, i). Spherical or ellipsoidal with cells 
distributed without order; with a stigma; 2 chromatophores; 
s warmer pyriform with 2 flagella; cells llju long; colony up to 100/z 
in diameter. 

Genus Phaeosphaera West and West. In a simple or branching 
cylindrical gelatinous mass; cells spherical with a single chroma- 
tophore; fresh water. 

P. gelatinosa W. and W. (Fig. 109, j, k). Cells 14-17.5/x in diameter. 


Butschli, O. : (1883-1887) Mastigophora. Bronn's Klassen und Ord- 

nungen des Thierreichs. 1, pt. 2. 
Doflein, F. and Reichenow, E. : (1949) Lehrbuch der Protozoen- 

kunde. 6th ed. 1. Jena. 
Grasse, P.-P.: (1952) Traite de Zoologie. I. Fasc. 1. Paris. 
Kent, S.: (1880-1882) A manual of Infusoria. London. 


Pascher, A.: (1914) Flagellatae: Allgemeiner Teil. In: Die Siisswas- 
serflora Deutschlands. Part 1. 

Stein, F.: (1878) Der Organismus der Infusionsthiere. 3 Abt. Leip- 

(1883) Der Organismus der Flagellate oder Geisselinfusorien. 

Parts 1, 2. Leipzig. 

Ahlstrom, E. H.: (1936) The deep-water plankton of Lake Michi- 
gan, exclusive of the Crustacea. Tr. Am. Micr. Soc, 55:286. 

(1937) Studies on variability in the genus Dinobryon. Ibid., 


Conrad, W.: (1926) Recherches sur les flagellates de nos eaux 
saumatres. II. Arch. Protist., 56:167. 

— ■ (1927) Essai d'une monographie des genres Mallomonas 

Perty (1852) et Pseudomallomonas Chodat (1920). Ibid., 59: 

(1928) Le genre Microglena. Ibid., 60:415. 

(1928a) Sur les Coccolithophoracees d'eau douce. Ibid., 63: 


(1930) Flagellates nouveaux ou peu connus. I. Ibid., 70:657. 

Deflandre, G.: (1952) Classe des Silicoflagellides. In: Grasse 

(1952), p. 425. 

(1952a) Classe des Coccolithophorides. Ibid., p. 440. 

Doflein, F.: (1921) Mitteilungen liber Chrysomonadien aus dem 

Schwarzwald. Zool. Anz., 53:153. 
(1922) Untersuchungen liber Chrysomonadinen. I, II. Arch. 

Protist., 44:149. 

(1923) III. Ibid., 45:267. 

Fritsch, F. E.: (1935) The structure and reproduction of the algae. 

Hollande, A.: (1952) Classe des Chrysomonadines. In: Grasse 
(1952), p. 471. 

Kamptner, E.: (1928) Ueber das System und die Phylogenie der 
Kalkflagellaten. Arch. Protist., 64: 19. 

Korshikov, A. A.: (1929) Studies on the chrysomonads. I. Ibid., 67: 

Lackey, J. B. : (1938) Scioto River forms of Chrysococcus. Am. Mid- 
land Natur., 20:619. 

- (1940) Some new flagellates from the Woods Hole area. Ibid., 

Owen,'h. M.: (1947) Flagellar structure. I. Tr. Am. Micr. Soc, 


(1949) II. Ibid., 68: 261. 

Pascher, A.: (1916) Studien liber die rhizopodiale Entwicklung der 

Flagellaten. Arch. Protist., 36:81. 
(1916a) Rhizopodialnetz als Fangvorrichtung bei einer plas- 

modialen Chrysomonade. Ibid., 37:15. 

— (1916b) Fusionsplasmodien bei Flagellaten und ihre Be- 
deutung fur die Ableitung der Rhizopoden von den Flagellaten. 
Ibid., 37:31. 


— (1917) Flagellaten und Rhizopoden in ihren gegenseitigen 
Beziehungen. Ibid., 38:584. 

— (1921) Neue oder wenig bekannte Protisten. Ibid., 44:119. 
(1929) XXI. Ibid., 65:426. 

Scherffel, A.: (1901) Kleiner Beitrag zur Phylogenie einiger Grup- 

pen niederer Organismen. Bot. Zeit., 59:143. 
(1927) Beitrag zur Kenntnis der Chrysomonadineen. II. 

Arch. Protist., 57:331. 
Schiller, J.: (1925) Die planktonischen Vegetationen des adriat- 

ischen Meeres. A. Ibid., 51:1. 

(1925a) B. Ibid., 53:59. 

(1926) Ueber Fortpflanzung, geissellose Gattungen und die 

Nomenklatur der Coccolithophoraceen, etc. Ibid., 53:326. 
(1926a) Der thermische Einfluss und die Wirkung des Eises 

auf die planktischen Herbstvegetationen, etc. Ibid., 56:1. 
■ — (1929) Neue Chryso- und Cryptomonaden aus Altwassern 

der Donau bei Wien. Ibid., 66:436. 
Smith, G. M.: (1950) The freshwater algae of the United States. 2 

ed. New York. 
Stokes, A. C.: (1888) A preliminary contribution toward a history 

of the freshwater Infusoria of the United States. J. Trenton 

Nat. Hist. Soc, 1:71. 
Troitzkaja, O. V.: (1924) Zur Morphologie und Entwicklungsge- 

schichte von Uroglenopsis americana. Arch. Protist., 49:260. 
West, G. S. and Fritsch, F. E.: (1927) A treatise on the British 

freshwater algae. Cambridge. 

Chapter 9 
Order 2 Cryptomonadina Stein 

THE cryptomonads differ from the chrysomonads in having a 
constant body form. Pseudopodia are very rarely formed, as 
the body is covered by a pellicle. The majority show dorso-ventral 
differentiation, with an oblique longitudinal furrow. 1-2 unequal 
flagella arise from the furrow or from the cytopharynx. In case 2 
flagella are present, both may be directed anteriorly or one poster- 
iorly. These organisms are free-swimming or creeping. 

One or two chromatophores are usually present. They are discoid 
or band-form. The color of chromatophores varies: yellow, brown, 
red, olive-green; the nature of the pigment is not well understood, 
but it is said to be similar to that which is found in the Dinoflagel- 
lata (Pascher). One or more spherical pyrenoids which are enclosed 
within a starch envelope appear to occur outside the chromato- 
phores. Nutrition is mostly holophytic; a few are saprozoic or holo- 
zoic. Assimilation products are solid discoid carbohydrates which 
stain blue with iodine in Cryptomonas or which stain reddish violet 
by iodine in Cryptochrysis ; fat and starch are produced in holo- 
zoic forms which feed upon bacteria and small Protozoa. The stigma 
is usually located near the insertion point of the flagella. Con- 
tractile vacuoles, one to several, are simple and are situated near the 
cytopharynx. A single vesicular nucleus is ordinarily located near 
the middle of the body. 

Asexual reproduction, by longitudinal fission, takes place in 
either the active or the non-motile stage. Sexual reproduction is un- 
known. Some cryptomonads form palmella stage and others gelati- 
nous aggregates. In the suborder Phaeocapsina, the palmella stage is 
permanent. Cysts are spherical, and the cyst wall is composed of 
cellulose. The Cryptomonadina occur in fresh or sea water, living 
also often as symbionts in marine organisms. 

Flagellate forms predominant Suborder 1 Eucryptomonadina 

Palmella stage permanent Suborder 2 Phaeocapsina (p. 275) 

Suborder 1 Eucryptomonadina Pascher 

Truncate anteriorly; 2 anterior flagella; with an oblique furrow near 
anterior end Family 1 Cryptomonadidae (p. 273) 

Reniform; with 2 lateral flagella; furrow equatorial 

Family 2 Nephroselmidae (p. 274) 




Family 1 Cryptomonadidae Stein 
Genus Cryptomonas Ehrenberg. Elliptical body with a firm pelli- 
cle; anterior end truncate, with 2 flagella; dorsal side convex, ventral 
side slightly so or flat; nucleus posterior; "cytopharynx" with gran- 
ules, considered trichocysts by some observers (Hollande, 1942, 
1952); 2 lateral chromatophores vary in color from green to blue- 
green, brown or rarely red; holophytic; with small starch-like bodies 
which stain blue in iodine; 1-3 contractile vacuoles anterior; fresh 
water. Several species. Morphology and taxonomy (Hollande, 1942, 

Fig. 111. a, Cryptomonas ovata, X800 (Pascher);b, Chilomonas Para- 
mecium, X1330 (Biitschli); c, d, Chrysidella schaudinni, X1330 (Winter); 
e, Cyathomonas truncata, X670 (Ulehla); f, Cryptochrysis commutata, 
X670 (Pascher); g, Rhodomonas lens, X1330 (Ruttner); h, Nephroselmis 
olvacea, X670 (Pascher) ; i, Protochrysis phaeophycearum, X800 (Pascher); 
j, k, Phaeothamnion confervicolum, X600 (Kiihn). 

C. ovata E. (Fig. Ill, a). 30-60/x by 20-25/x; among vegetation. 

Genus Chilomonas Ehrenberg. Similar to Cryptomonas in general 
body form and structure, but colorless because of the absence of 
chromatophores; without pyrenoid; "cytopharynx" deep, lower half 
surrounded by granules, considered by Hollande (1942) and Drag- 
esco (1951) as trichocysts; one contractile vacuole anterior; nucleus 
in posterior half; endoplasm usually filled with polygonal starch 
grains; saprozoic fresh water. 

C. Paramecium E. (Fig. 111,6). Posteriorly narrowed, slightly bent 
"dorsally"; 30-40 m by 10-1 5m; saprozoic; widely distributed in stag- 


nant water. Cytology (Mast and Doyle, 1935; Hollande, 1942; 
Dragesco, 1951); bacteria-free culture (Mast and Pace, 1933); me- 
tabolism (Mast and Pace, 1929; Pace, 1941); growth substances 
(Pace, 1944, 1947; Mast and Pace, 1946); effects of vitamins (Pace, 

C. oblonga Pascher. Oblong; posterior end broadly rounded; 20- 
50/i long. 

Genus Chrysidella Pascher. Somewhat similar to Cryptomonas- 
but much smaller-, yellow chromatophores much shorter; those oc, 
curring in Foraminifera or Radiolaria as symbionts are known as 
Zooxanthellae. Several species. 

C. schaudinni (Winter) (Fig. Ill, c, d). Body less than 10m long; in 
the foraminiferan Peneroplis pertusus. 

Genus Cyathomonas Fromentel. Body small, somewhat oval; 
without chromatophores; much compressed; anterior end obliquely 
truncate; with 2 equal or subequal anterior flagella; colorless; nu- 
cleus central; anabolic products, stained red or reddish violet by 
iodine; contractile vacuole usually anterior; a row of refractile 
granules, protrichocysts, close and parallel to anterior margin of 
body; asexual reproduction by longitudinal fission; holozoic; in stag- 
nant water and infusion. One species. 

C. truncata Ehrenberg (Fig. Ill, e). 15-25ju by 10-15/i. 

Genus Cryptochrysis Pascher. Furrow indistinctly granulated; 
2 or more chromatophores brownish, olive-green, or dark green, 
rarely red; pyrenoid central; 2 equal flagella; some lose flagella and 
may assume amoeboid form ; fresh water. 

C. commutataV. (Fig. Ill, /). Bean-shaped; 2 chromatophores; 
19/x by 10m. 

Genus Rhodomonas Karsten. Furrow granulated; chromatophore 
one, red (upon degeneration the coloring matter becomes dissolved 
in water) ; pyrenoid central ; fresh water. 

R. lens Pascher and Ruttner (Fig. Ill, g). Spindle-form; about 16m 
long; in fresh water. 

Family 2 Nephroselmidae Pascher 

Body reniform; with lateral equatorial furrow; 2 flagella arising 
from furrow, one directed anteriorly and the other posteriorly. 

Genus Nephroselmis Stein. Reniform; flattened; furrow and 
cytopharynx distinct; no stigma; 1-2 chromatophores, discoid, 
brownish green; nucleus dorsal; a central pyrenoid; 2 contractile 
vacuoles; with reddish globules; fresh water. 

N. olvacea S. (Fig. Ill, h). 20-25m by 15m- 


Genus Protochrysis Pascher. Reniform; not flattened; with a dis- 
tinct furrow, but without cytopharynx; a stigma at base of flagella; 
1-2 chromatophores, brownish yellow; pyrenoid central; 2 contrac- 
tile vacuoles ; fission seems to take place during the resting stage ; 
fresh water. 

P. phaeophycearum P. (Fig. Ill, i). 15-17/z by 7-9//. 

Suborder 2 Phaeocapsina Pascher 

Palmella stage predominant; perhaps border-line forms between 
brown algae and cryptomonads. Example: Phaeothamnion confer- 
vicolum Lagerheim (Fig. Ill, j, k) which is less than 10// long. 


Dragesco, J.: (1951) Sur la structure des trichocystes du flagelle 

cryptomonadine, Chilomonas paramecium. Bull. micr. appl., 2 

ser. 1:172. 
Fritsch, F. E. : (1935) The structure and reproduction of the algae. 

Hollande, A.: (1942) Etude cytologique et biologique de quelques 

flagell^s libres. Arch. zool. exper. g£n., 83:1. 
(1952) Classe des Cryptomonadines. In: Grasse (1952), p. 

Mast, S. O. and Doyle, W. L.: (1935) A new type of cytoplasmic 

structure in the flagellate Chilomonas paramecium. Arch.Protist., 

and Pace, D. M. : (1933) Synthesis from inorganic compound 

of starch, fats, proteins and protoplasm in the colorless animal, 

Chilomonas paramecium. Protoplasma, 20:326. 

(1939) The effect of calcium and magnesium on 

metabolic processes in Chilomonas. J. Cell. Comp. Physiol., 14: 

(1946) The nature of the growth-substance produced 

by Chilomonas paramecium. Physiol. Zool., 19:223. 

Pace, D. M.: (1941) The effects of sodium and potassium on meta- 
bolic processes in Chilomonas paramecium. J. Cell. Comp. 
Physiol., 18:243. 

(1944) The relation between concentration of growth-pro- 
moting substance and its effect on growth in Chilomonas para- 
mecium. Physiol. Zool., 17:278. 

(1947) The effects of vitamins and growth-promoting sub- 
stance on growth in Chilomonas paramecium. Exper. Med. Surg. 

Pascher, A.: (1913) Cryptomonadinae. Susswasserflora Deutsch- 
lands. 2. 

West, G. S. and Fritsch, F. E.: (1927) A treatise on the British 
freshwater algae. Cambridge. 

Chapter 10 
Order 3 Phytomonadina Blochmann 

THE phytomonads are small, more or less rounded, green flagel- 
lates, with a close resemblance to the algae. They show a definite 
body form, and most of them possess a cellulose membrane, which 
is thick in some and thin in others. There is a distinct opening in 
the membrane at the anterior end, through which 1-2 (or 4 or 
more) flagella protrude. The majority possess numerous grass-green 
chromatophores, each of which contains one or more pyrenoids. The 
method of nutrition is mostly holophytic or mixotrophic; some color- 
less forms are, however, saprozoic. The metabolic products are 
usually starch and oils. Some plr^tomonads are stained red, owing 
to the presence of haematochrome. The contractile vacuoles may be 
located in the anterior part or scattered throughout the body. The 
nucleus is ordinarily centrally located, and its division seems to be 
mitotic, chromosomes having been definitely noted in several species. 

Asexual reproduction is by longitudinal fission, and the daughter 
individuals remain within the parent membrane for some time. 
Sexual reproduction seems to occur widely. Colony formation also 
occurs, especially in the family Volvocidae. Encystment and forma- 
tion of the palmella stage are common among many forms. The 
phytomonads have a much wider distribution in fresh than in salt 

Membrane a single piece; rarely indistinct 

2 flagella Family 1 Chlamydomonadidae 

3 flagella Family 2 Trichlorididae (p. 281) 

4 flagella Family 3 Carteriidae (p. 281) 

5 flagella Family 4 Chlorasteridae (p. 283) 

6 or more flagella Family 5 Polyblepharididae (p. 284) 

Membrane bivalve Family 6 Phacotidae (p. 284) 

Colonial, of 4 or more individuals; 2 (1 or 4) flagella 

Family 7 Volvocidae (p. 285) 

Family 1 Chlamydomonadidae Butschli 

Solitary; spheroid, oval, or ellipsoid; with a cellulose membrane; 
2 flagella; chromatophores, stigma, and pyrenoids usually present. 
Cytology (Hollande, 1942). 

Genus Chlamydomonas Ehrenberg. Spherical, ovoid or elongated; 
sometimes flattened; 2 flagella; membrane often thickened at an- 
terior end; a large chromatophore, containing one or more pyrenoids; 



stigma; a single nucleus; 2 contractile vacuoles anterior; asexual 
reproduction and palmella formation; sexual reproduction isogamy 
or anisogamy; fresh water. Numerous species (Pascher, 1921, 1925, 
1929, 1930, 1932: Skvortzow, 1929; Pringsheim, 1930; Pascher and 
Jahoda, 1928; Moewus, 1932, 1933; Gerloff, 1940); variation (Moe- 
wus, 1933) ; sexual development (Moewus, 1933a) ; variation (p. 223) ; 
genetics (p. 231). 

C. monadina Stein (Fig. 112, a-c). 15-30/x long; fresh water; 
Landacre noted that the organisms obstructed the sand filters used in 
connection with a septic tank, together with the diatom Navicula. 

C. angulosa Dill. About 20^u by 12-15/z; fresh water. 

C. epiphytica Smith (Fig. 112, d). 8-9/j, by 7-8/*; in freshwater lakes. 

C. globosa Snow (Fig. 112, e). Spheroid or ellipsoid; 5-7 n in dia- 
meter; in freshwater lakes. 

C. gracilis S. (Fig. 112,/). 10-13/x by 5-7 n; fresh water. 

Genus Haematococcus Agardh (Sphaerella Sommerfeldt). Sphe- 
roidal or ovoid with a gelatinous envelope ; chromatophore peripheral 
and reticulate, with 2-8 scattered pyrenoids; several contractile 
vacuoles; haematochrome frequently abundant in both motile and 
encysted stages; asexual reproduction in motile form; sexual repro- 
duction isogamy; fresh water. 

H. pluvialis (Flotow) (Figs. 42; 112, g). Spherical; with numerous 
radial cytoplasmic processes; chromatophore U-shape in optical sec- 
tion; body 8-50m, stigma fusiform, lateral; fresh water. Reichenow 
(1909) noticed the disappearance of haematochrome if the culture 
medium was rich in nitrogen and phosphorus. In bacteria-free cul- 
tures, Elliott (1934) observed 4 types of cells: large and small flagel- 
lates, palmella stage and haemato cysts. Large flagellates predominate 
in liquid cultures, but when conditions become unfavorable, palmella 
stage and then haematocysts develop. When the cysts are placed in 
a favorable environment after exposure to freezing, desiccation, etc., 
they give rise to small flagellates which grow into palmella stage or 
large flagellates. No syngamy of small flagellates was noticed. Hae- 
matochrome appears during certain phases in sunlight and its ap- 
pearance is accelerated by sodium acetate under sunlight. Sexuality 
(Schulze, 1927). 

Genus Sphaerellopsis Korschikoff (Chlamydococcus Stein). With 
gelatinous envelope which is usually ellipsoid with rounded ends; 
body elongate fusiform or pyriform, no protoplasmic processes to 
envelope; 2 equally long flagella; chromatophore large; a pyrenoid; 
with or without stigma; nucleus in anterior half; 2 contractile vacu- 
oles; fresh water. 



S. fluviatilis (Stein) (Fig. 112, h). 14-30/zby 10-20m; fresh water. 

Genus Brachiomonas Bohlin. Lobate; with horn-like processes, 
all directed posteriorly; contractile vacuoles; ill-defined chromato- 
phore; pyrenoids; with or without stigma; sexual and asexual re- 
production; fresh, brackish or salt water. 

Fig. 112. a-c, Chlamydomonas monadina, X470 (Goroschankin) (a, 
typical organism; b, anisogamy; c, palmella stage); d, C. epiphytica, 
X1030 (Smith); e, C. globosa, X2000 (Snow); f, C. gracilis, X770 (Snow); 
g, Haematococcus pluvialis, X500 (Reichenow); h, Sphaerellopsis fluvia- 
tilis, X490 (Korschikoff); i, Brachiomonas westiana, X960 (West); j, 
Lobomonas rostrata, X1335 (Hazen); k, Diplostauron pentagonium, X1110 
(Hazen); 1, Gigantochloris permaxima, X370 (Pascher); m, Gloeomonas 
ovalis, X330 (Pascher); n, Scourfieldia complanata, X1540 (West); o, 
Thorakomonas sabulosa, X670 (Korschikoff). 


B. westiana Pascher (Fig. 112, i). 15-24/t by 13-23/z; brackish 

Genus Lobomonas Dangeard. Ovoid or irregularly angular; chro 
matophore cup-shaped; pyrenoid; stigma; a contractile vacuole, 
fresh water. 

L. rostrata Hazen (Fig. 112, j). 5-12 /i by 4-8 /*. 

Genus Diplostauron Korschikoff. Rectangular with raised cor- 
ners; 2 equally long flagella; chromatophore; one pyrenoid; stigma; 
2 contractile vacuoles anterior; fresh water. 

D. pentagonium (Hazen) (Fig. 112, k). 10-13/* by 9— 10m- 

Genus Gigantochloris Pascher. Unusually large form, equalling 
in size a colony of Eudorina; flattened; oval in front view; elongate 
ellipsoid in profile; membrane radially striated; 2 flagella widely 
apart, less than body length; chromatophore in network; numerous 
pyrenoids; often without stigma; in woodland pools. 

G. permaxima P. (Fig. 1 12, 1). 70-150/* by 40-80/x by 25-50/*. 

Genus Gloeomonas Klebs. Broadly ovoid, nearly subspherical; 
with a delicate membrane and a thin gelatinous envelope; 2 flagella 
widely apart; chromatophores numerous, circular or oval discs; 
pyrenoids (?); stigma; 2 contractile vacuoles anterior; freshwater. 

G. ovalis K. (Fig. 112, m). 38-42/x by 23-33/*; gelatinous envelope 
over 2/* thick. 

Genus Scourfieldia West. Whole body flattened; ovoid in front 
view; membrane delicate; 2 flagella 2-5 times body length; a chro- 
matophore; without pyrenoid or stigma; contractile vacuole anter- 
ior; nucleus central; fresh water. 

S. complanata W. (Fig. 112, n). 5.2-5. 7/* by 4. 4-4. 6m ; fresh water. 

Genus Thorakomonas Korschikoff. Flattened; somewhat irregu- 
larly shaped or ellipsoid in front view; membrane thick, enclustered 
with iron-bearing material, deep brown to black in color; proto- 
plasmic body similar to that of Chlamydomonas; a chromatophore 
with a pyrenoid; 2 contractile vacuoles; standing fresh water. 

T. sabulosa K. (Fig. 112, o). Up to 16// by 14/*. 

Genus Coccomonas Stein. Shell smooth; globular; body not filling 
intracapsular space; stigma; contractile vacuole; asexual reproduc- 
tion into 4 individuals ; fresh water. Species (Conrad 1930). 

C. orbicularis S. (Fig. 113, a). 18-25/1 in diameter; fresh water. 
Genus Chlorogonium Ehrenberg. Fusiform; membrane thin and 

adheres closely to protoplasmic body; plate-like chromatophores 
usually present, sometimes ill-contoured; one or more pyrenoids; 
numerous scattered contractile vacuoles; usually a stigma; a central 
nucleus; asexual reproduction by 2 successive transverse fissions 



during the motile phase; isogamy reported; fresh water. 

during the motile phase; isogamy reported; fresh water. Sexuality 

(Schulze, 1927); nutrition (Loefer, 1935). 

C. euchlorum E. (Fig. 113, b). 25-70/1 by 4-1 5/x; in stagnant water. 

Genus Phyllomonas Korschikoff. Extremely flattened ; membrane 
delicate; 2 flagella; chromatophore often faded or indistinct; numer- 
ous pyrenoids; with or without stigma; many contractile vacuoles; 
fresh water. 

Fig. 113. a, Coccomonas orbicularis, X500 (Stein); b, Chlorogonium 
euchlorum, X430 (Jacobsen); c, Phyllomonas phacoides, X200 (Kor- 
schikoff); d, Sphaenochloris printzi, X600 (Printz); e, Korschikoffia 
guttula, X1670 (Pascher); f, Fur cilia lobosa, X670 (Stokes); g, Hyalo- 
gonium klebsi, X470 (Klebs); h, Polytoma uvella, X670 (Dangeard); 
i, Parapolytoma satura, X1600 (Jameson); j, Trichloris paradoxa, X990 

P. phacoides K. (Fig. 113, c). Leaf -like; rotation movement; up to 
100/i long; in standing fresh water. 

Genus Sphaenochloris Pascher. Body truncate or concave at flagel- 
late end in front view; sharply pointed in profile; 2 flagella widely 
apart; chromatophore large; pyrenoid; stigma; contractile vacuole 
anterior; fresh water. 

S. printzi P. (Fig. 113, d). Up to 18/x by 9/*. 

Genus Korschikoffia Pascher. Elongate pyriform with an undu- 
lating outline; anterior end narrow, posterior end more bluntly 
rounded; plastic; chromatophores in posterior half; stigma absent; 
contractile vacuole anterior; 2 equally long flagella; nucleus nearly 
central ; salt water. 


K. guttula P. (Fig. 113, e). 6-lOyu by 5m; brackish water. 

Genus Furcilla Stokes. U-shape, with 2 posterior processes; in 
side view somewhat flattened; anterior end with a papilla; 2 flagella 
equally long; 1-2 contractile vacuoles anterior; oil droplets; fresh 

F. lobosa S. (Fig. 113,/). 11-14 M long; fresh water. 

Genus Hyalogonium Pascher. Elongate spindle-form ; anterior end 
bluntly rounded; posterior end more pointed; 2 flagella; protoplasm 
colorless; with starch granules; a stigma; asexual reproduction re- 
sults in up to 8 daughter cells; fresh water. 

H. klebsi P. (Fig. 113, g). 30-80/x by up to 10m; stagnant water. 

Genus Polytoma Ehrenberg (Chlamydoblepharis France; Tussetia 
Pascher). Ovoid; no chromatophores; membrane yellowish to 
brown; pyrenoid unobserved; 2 contractile vacuoles; 2 flagella 
about body length; stigma if present, red or pale-colored; many 
starch bodies and oil droplets in posterior half of body; asexual re- 
production in motile stage; isogamy (Dogiel, 1935); saprozoic; in 
stagnant fresh water. Genetics (p. 231). 

P. uvella E. (Figs. 8, c; 97, a, b; 113, h). Oval to pyriform; stigma 
may be absent; 15-30/x by 9-20m- Cytology (Entz, 1918; Hollande, 

Genus Parapolytoma Jameson. Anterior margin obliquely trun- 
cate, resembling a cryptomonad, but without chromatophores; with- 
out stigma and starch; division into 4 individuals within envelope; 
fresh water. 

P. satura J. (Fig. 113, i). About 15m by 10m; fresh water. 

Family 2 Trichlorididae 

Genus Trichloris Scherffel and Pascher. Bean-shape; flagellate 
side flattened or concave; opposite side convex; chromatophore 
large, covering convex side; 2 pyrenoids surrounded by starch 
granules; a stigma near posterior end of chromatophore; nucleus 
central; numerous contractile vacuoles scattered; 3 flagella near 
anterior end. 

T. paradoxa S and P. (Fig. 113, j). 12-15/x broad by 10-12 M high; 
flagella up to 30m long. 

Family 3 Carteriidae 

Genus Carteria Diesing (Corbierea, Pithiscus Dangeard). Ovoid, 
chromatophore cup-shaped; pyrenoid; stigma; 2 contractile vacuoles; 
fresh water. Numerous species (Pascher, 1925, 1932; Schiller, 1925). 



C. cordiformis (Carter) (Fig. 114, a). Heart-shaped in front view; 
ovoid in profile; chromatophore large; 18-23/x by 16-20/t. 

C. ellipsoidalis Bold. Ellipsoid; chromatophore; a small stigma; 
division into 2, 4, or 8 individuals in encysted stage; 6-24/x long; 
fresh water, Maryland (Bold, 1938). 

Genus Pyramimonas Schmarda (Pyramidomonas Stein). Small 
pyramidal or heart-shaped body; with bluntly drawn-out posterior 
end; usually 4 ridges in anterior region; 4 flagella; green chromato- 
phore cup-shaped; with or without stigma; a large pyrenoid in the 
posterior part; 2 contractile vacuoles in the anterior portion ;'encyst- 
ment; fresh water. Several species (Geitler, 1925). 

P. tetrarhynchus S. (Fig. 114, b). 20-28/* by 12-18/*; fresh water; 
Wisconsin (Smith, 1933). 

Fig. 114. a, Carteria cordiformis, X600 (Dill); b, Pyramimonas tetra- 
rhynchus, X400 (Dill); c, d, Polytomella agilis, X1000 (Doflein) (d, a 
cyst) ; e, Spirogonium chlorogonioides, X 670 (Pascher) ; /, Tetrablepharis 
7nultifilis, X670 (Pascher); g, Spermatozopsis exultans, XI 630 (Pascher); 
h, Chloraster gyrans, X670 (Stein); i, Polyblepharides singularis, X870 
(Dangeard); j, k, Pocillomonas flos aquae, X920 (Steinecke); 1, m, Phaco- 
tus lenticularis, X430 (Stein); nj Pteromonas angulosa, X670 (West); o, p, 
Dysmorphococcus variabilis, X1000 (Bold). 


P. montana Geitler. Bluntly conical; anterior end 4-lobed or 
truncate; posterior end narrowly rounded; plastic; pyriform nucleus 
anterior, closely associated with 4 flagella; stigma; 2 contractile 
vacuoles anterior; chromatophore cup-shaped, granular, with scat- 
tered starch grains and oil droplets ; a pyrenoid with a ring of small 
starch grains; 17-22.5/1 long (Geitler, 1925); 12-20/* by 8-16/* 
(Bold); flagella about body length; fresh water, Maryland (Bold, 

Genus Polytomella Aragao. Ellipsoid, or oval, with a small papilla 
at anterior end, where 4 equally long flagella arise ; with or without 
stigma; starch: fresh water (Aragao, 1910; Doflein, 1916). 

P. agilis A. (Fig. 114, c, d). Numerous starch grains; 8—18/* by 
5-9/*; flagella 12-17/* long; fresh water; hay infusion. 

P. caeca Pringsheim. Ovoid with bluntly pointed posterior end; 
12-20/* by 10-12/*; membrane delicate; a small papilla at anterior 
end; no stigma; two contractile vacuoles below papilla; cytoplasm 
ordinarily filled with starch grains; fresh water (Pringsheim, 1937). 

Genus Medusochloris Pascher. Hollowed hemisphere with 4 proc- 
esses, each bearing a flagellum at its lower edge; a lobed plate- 
shaped chromatophore; without pyrenoid. One species. 

M. phiale P. In salt water pools with decaying algae in the Baltic. 

Genus Spirogonium Pascher. Body spindle-form; membrane deli- 
cate; flagella a little longer than body; chromatophore conspicuous; 
a pyrenoid; stigma anterior; 2 contractile vacuoles; fresh water. One 

S. chlorogonioides (P). (Fig. 114, e). Body up to 25/* by 15/*. 

Genus Tetrablepharis Senn. Ellipsoid to ovoid; pyrenoid present; 
fresh water. 

T. multifilis (Klebs) (Fig. 114,/). 12-20/* by 8-15/*; stagnant water. 

Genus Spermatozopsis Korschikoff. Sickle-form; bent easily, oc- 
casionally plastic; chromatophore mostly on convex side; a distinct 
stigma at more rounded anterior end; flagella equally long; 2 con- 
tractile vacuoles anterior; fresh water infusion. 

S. exultans K. (Fig. 114, g). 7-9/* long; also biflagellate ; in fresh 
water with algae, leaves, etc. 

Family 4 Chlorasteridae 

Genus Chloraster Ehrenberg. Similar to Pyramimonas, but an- 
terior half with a conical envelope drawn out at four corners; with 5 
flagella; fresh or salt water. 

C. gyrans E. (Fig. 114, h). Up to 18/* long; standing water; also re- 
ported from salt water. 


Family 5 Polyblepharididae Dangeard 

Genus Polyblepharides Dangeard. Ellipsoid or ovoid; flagella 6-8, 
shorter than body length; chromatophore; a pyrenoid; a central 
nucleus; 2 contractile vacuoles anterior; cysts; a questionable genus; 
fresh water. 

P. singularis D. (Fig. 114, i). 10-14 M by 8-9/x. 

Genus Pocillomonas Steinecke. Ovoid with broadly concave an- 
terior end; covered with gelatinous substance with numerous small 
projections; 6 flagella; chromatophores disc-shaped; 2 contractile 
vacuoles anterior; nucleus central; starch bodies; without pyrenoid. 

P.flos aquae S. (Fig. 114, j, k). 13m by 10m; fresh water pools. 

Family 6 Phacotidae Poche 

The shell typically composed of 2 valves; 2 flagella protrude from 
anterior end; with stigma and chromatophores; asexual reproduction 
within the shell ; valves may become separated from each other ow- 
ing to an increase in gelatinous contents. 

Genus Phacotus Perty. Oval to circular in front view; lenticular 
in profile; protoplasmic body does not fill dark-colored shell com- 
pletely; flagella protrude through a foramen; asexual reproduction 
into 2 to 8 individuals ; fresh water. 

P. lenticularis (Ehrenberg) (Fig. 114, I, m). 13-20m in diameter; in 
stagnant water. 

Genus Pteromonas Seligo. Body broadly winged in plane of suture 
of 2 valves; protoplasmic body fills shell; chromatophore cup- 
shaped; one or more pyrenoids; stigma; 2 contractile vacuoles; 
asexual reproduction into 2-4 individuals; sexual reproduction by 
isogamy; zygotes usually brown; fresh water. Several species. 

P. angulosa (Lemmermann) (Fig. 114, n). With a rounded wing 
and 4 protoplasmic projections in profile; 13-17/i by 9-20m; fresh 

Genus Dysmorphococcus Takeda. Circular in front view; anterior 
region narrowed; posterior end broad; shell distinctly flattened pos- 
teriorly, ornamented by numerous pores; sutural ridge without 
pores; 2 flagella; 2 contractile vacuoles; stigma, pyrenoid, cup-shaped 
chromatophore; nucleus; multiplication by binary fission; fresh 

D. variabilis T. (Fig. 114, o, p). Shell 14-19/x by 13-17/x; older shells 
dark brown; fresh water; Maryland (Bold, 1938). 


Family 7 Volvocidae Ehrenberg 

An interesting group of colonial flagellates; individual similar to 
Chlamydomonadidae, with 2 equally long flagella (one in Mastigo- 
sphaera; 4 in Spondylomorum) , green chromatophores, pyrenoids, 
stigma, and contractile vacuoles; body covered by a cellulose mem- 
brane and not plastic; colony or coenobium is discoid or spherical; 
exclusively freshwater inhabitants. 

Genus Volvox Linnaeus. Often large spherical or subspherical 
colonies, consisting of a large number of cells which are differen- 
tiated into somatic and reproductive cells; somatic cells numerous, 
embedded in gelatinous matrix, and contains a chromatophore, 
one or more pyrenoids, a stigma, 2 flagella and several contractile 
vacuoles; in some species cytoplasmic connection occurs between ad- 
jacent cells; generative cells few and large. Reproduction is by 
parthenogenesis or true sexual fusion. In parthenogenetic colonies, 
the gametes are larger in size and fewer in number as compared with 
the macrogametes of the female colonies. Sexual fusion is anisogamy 
(Fig. 77) and sexual colonies may be monoecious or dioecious. Zy- 
gotes are usually yellowish to brownish red in color and covered by a 
smooth, ridged or spinous wall. Fresh water. Many species. Smith 
(1944) made a comprehensive study of 18 species on which the fol- 
lowing species descriptions are based. 

V. globator L. (Fig. 115, a, b). Monoecious. Sexual colonies 350- 
500m in diameter; 5000-15,000 cells, with cytoplasmic connections; 
3-7 microgametocytes, each of which develops into over 250 micro- 
gametes; 10-40 macrogametes; zygotes 35-45/1 in diameter, covered 
with many spines with rounded tip. Parthenogenetic colonies 400- 
GOO/i in diameter; 4-10 gametes, 10-13/i in diameter; young colonies 
up to 250/i. Europe and North America. 

V. aureus Ehrenberg (Figs. 77; 115, c-e). Dioecious. Male colonies 
300-350/* in diameter; 1000-1500 cells, with cytoplasmic connec- 
tions; numerous microgametocytes; clusters of some 32 microgam- 
etes, 15-18/x in diameter. Female colonies 300-400/*; 2000-3000 
cells; 10-14 macrogametes; zygotes 40-60/x with smooth surface. 
Parthenogenetic colonies up to 500/z; 4-12 gametes; young colonies 
150/x in diameter. Europe and North America. Sexual differentiation 
(Mainx, 1929). 

V. tertius Meyer. Dioecious. Male colonies up to 170/t in diameter; 
180-500 cells, without cytoplasmic connections; about 50 micro- 
gametocytes. Female colonies up to 500ju; 500-2000 cells; 2-12 
macrogametes; zygotes 60-65/i with smooth wall. Parthenogenetic 



^oo o ° o ° ° o ooocS?: 
•oo° °„ o.o ° o „ of 


Ns( %& 

D o"W 

Fig. 115. Species of Volvox ("Smith), a, b, Volvox globator (a, a female 
colony, X150; b, a zygote, X370); c-e, V. aureus (c, a young partheno- 
genetic colony; d, a mature male colony, X125; e, a zygote, X370); f-h, 
V. spermatosphaera: f, a parthenogenetic colony, X185; g, a mature male 
colony, X370; h, a zygote, X370); i, a zygote of V. weismannia, X370; 
j, k, V. per globator (j, a male colony, XI 50; k, a zygote, X370). 


colonies up to 600 m in diameter; 500-2000 cells; 2-12 gametes. 
Europe and North America. 

V. spermatosphaera Powers (Fig. 115, f-h). Dioecious. Male colo- 
nies up to 100m in diameter; cells, without connection, up to 128 
microgametocytes. Female colonies up to 500 n in diameter; 6-16 
macrogametes; zygotes 35-45/1, with smooth membrane. Partheno- 
genetic colonies up to 650/x in diameter; 8-10 gametes; young colo- 
nies ellipsoid, up to 100 ju in diameter. North America (Powers, 1908). 

V. weismannia P. (Fig. 115, i). Male colonies 100-150/z in diam- 
eter; 250-500 cells; 6-50 microgametocytes; clusters of microgametes 
(up to 128) discoid, 12-15/t in diameter. Female colonies up to 400/*; 
2000-3000 cells; 8-24 macrogametes; zygotes 30-50ju in diameter, 
with reticulate ridges on shell. Parthenogenetic colonies up to 400/z; 
1500-3000 cells; 8 or 10 gametes; 40-60/x in diameter; young colonies 
1 00-200 /x in diameter. North America (Powers, 1908). 

V. perglobator P. (Fig. 115, j, k). Dioecious. Male colonies 300- 
450/x in diameter 5000-10,000 cells, with delicate cytoplasmic con- 
nections; 60-80 microgametocytes. Female colonies 300-550/z in di- 
ameter; 9000-13,000 cells; 50-120 macrogametes; zygotes 30-34/x, 
covered with bluntly pointed spines. Parthenogenetic colonies as 
large as 1.1 mm; three to nine gametes; young colonies 250-275/x in 
diameter. North America. 

Genus Gonium Miiller. 4 or 16 individuals arranged in one plane; 
cell ovoid or slightly polygonal; with 2 flagella arranged in the plane 
of coenobium; with or without a gelatinous envelope; protoplasmic 
connections among individuals occur occasionally; asexual reproduc- 
tion through simultaneous divisions of component cells; sexual re- 
production isogamy; zygotes reddish; fresh water. Colony formation 
(Hartmann, 1924). 

G. sociale (Dujardin) (Fig. 116, a). 4 individuals form a discoid 
colony; cells 10-22/* by 6-16// wide; in open waters of ponds and 

G. pectorale M. (Fig. 116, b). 16 (rarely 4 or 8) individuals form a 
colony; 4 cells in center; 12 peripheral, closely arranged; cells 5-14/x 
by 10/x; colony up to 90/z in diameter; fresh water. 

G. /orraoswm Pascher. 16 cells in a colony further apart; peripheral 
gelatinous envelope reduced; cells similar in size to those of G. so- 
ciale but colony somewhat larger; freshwater lakes. 

Genus Stephanoon Schewiakoff. Spherical or ellipsoidal colony, 
surrounded by gelatinous envelope, and composed of 8 or 16 bi- 



flagellate cells, arranged in 2 alternating rows on equatorial plane; 
fresh water. 

S. askenasii S. (Fig. 117, a). 16 individuals in ellipsoidal colony; 
cells 9/x in diameter; flagella up to 30/t long; colony 78/* by 60/z- 

Genus Platydorina Kofoid. 32 cells arranged in a slightly twisted 
plane; flagella directed alternately to both sides; dioecious; fresh 

P. caudata K. (Fig. 117, b). Individual cells 10-15/t long; colony 
up to 165m long by 145ju wide, and 25/u thick; dioecious; anisogamy; 
macrogametes escape from female colonies and remain attached to 

Fig. 116. a, Gonium sociale, X270 CChodat); b, G. pec- 
torale, X670 CHartmann). 

them or swim about until fertilized by microgametes; zygotes be- 
come thickly walled (Taft, 1940). 

Genus Spondylomorum Ehrenberg. 16 cells in a compact group in 
4 transverse rings; each with 4 flagella; asexual reproduction by 
simultaneous division of component cells; fresh water. One species. 

S. quaternarium E. (Fig. 117, c). Cells 12-26/x by 8-15/i; colony 
up to 60ju long. 

Genus Chlamydobotrys Korschikoff. Colony composed of 8 or 16 
individuals; cells with 2 flagella; chromatophore; stigma ; no 
pyrenoid; fresh water. Species (Pascher, 1925); culture (Schulze, 

C. stellata K. (Fig. 117, d). Colony composed of 8 individuals 
arranged in 2 rings; individuals 14-15m long; colony 30-40/1 in 
diameter; Maryland (Bold, 1933). 



Genus Stephanosphaera Cohn. Spherical or subspherical colony, 
with 8 (rarely 4 or 16) cells arranged in a ring; cells pyriform, but 
with several processes; 2 flagella on one face; asexual reproduction 
and isogamy (p. 183) ; fresh water. 

Fig. 117. a, Stephanoon askenasii, X440 (Schewiakoff); b, Platydorina 
caudata, X2S0 (Kofoid); c, Spondylomorum quaternarium, X330 (Stein); 
d, Chlamydobotrys stellata, X430 (Korschikoff) ; e, Stephanosphaera plu- 
vialis, X250 (Hieronymus) ; f, Pandorina morum, X300 (Smith); g, 
Mastigosphaera gobii, X520 (Schewiakoff ) ; h, Eudorina elegans, X310 
(Goebel); i, Pleodorina illinoisensis, X200 (Kofoid). 

S. pluvialis C. (Figs. 80; 117, e). Cells 7-13m long; colony 30-60/x 
in diameter. Culture and sexuality (Schulze, 1927). 

Genus Pandorina Bory. Spherical or subspherical colony of usu- 
ally 16 (sometimes 8 or 32) biflagellate individuals, closely packed 
within a gelatinous, but firm and thick matrix; individuals often 
angular; with stigma and chromatophores; asexual reproduction 


through simultaneous division of component individuals; anisog- 
amy; zygotes colored and covered by a smooth wall; fresh water. 
One species. 

P. morum (Miiller) (Figs. 117, /). Cells 8-17/z long; colony 20- 
40/x, up to 250/z in diameter; ponds and ditches. 

Genus Mastigosphaera Schewiakoff. Similar to Pandorina; but 
individuals with a single flagellum which is 3.5 times the body length; 
fresh water. 

M. gobii S. (Fig. 117, g). Individual 9m long; colony 30-33/*. 

Genus Eudorina Ehrenberg. Spherical or ellipsoidal colony of 
usually 32 or sometimes 16 spherical cells; asexual reproduction 
similar to that of Pandorina; sexual reproduction with 32-64 spheri- 
cal green macrogametes and numerous clustered microgametes which 
when mature, unite with the macrogametes within the colony; red- 
dish zygotes with a smooth wall; fresh water. Colony formation 
(Hartmann, 1924). 

E. elegans E. (Fig. 117, h). Cells 10-24^ in diameter; colony 40- 
150 fx in diameter; in ponds, ditches and lakes. Culture and morphol- 
ogy (Hartmann, 1921); response to light (Luntz, 1935). 

Genus Pleodorina Shaw. Somewhat similar to Eudorina, being 
composed of 32, 64, or 128 ovoid or spherical cells of 2 types: small 
somatic and large generative, located within a gelatinous matrix; 
Sexual reproduction similar to that of Eudorina; fresh water. 

P. illinoisensis Kofoid (Figs. 32, b, c; 117, i). 32 cells in ellipsoid 
colony, 4 vegetative and 28 reproductive individuals; arranged in 
5 circles, 4 in each polar circle, 8 at equator and 8 on either side of 
equator; 4 small vegetative cells at anterior pole; vegetative cells 
10-16/x in diameter; reproductive cells 19-25/x in diameter; colony 
up to 160m by 130/z. 

P. californica S. Spherical colony with 64 or 128 cells, of which 
1/2-2/3 are reproductive cells; vegetative cells 13-1 5m; reproductive 
cells up to 27/x; colony up to 450/x, both in diameter. Variation (Tif- 
fany, 1935); in Ukraine (Swirenko, 1926). 


Aragao, H. B.: (1910) Untersuchungen iiber Polytomella agilis n.g., 

n. sp. Mem. Inst. Oswaldo Cruz, 2:42. 
Bold, H. C: (1938) Notes on Maryland algae. Bull. Torrey Bot. 

Club., 65:293. 
Conrad, W. : (1930) Flagellates nouveaux ou peu connus. I. Arch. 

Protist., 70:657. 
Crow, W. B.: (1918) The classification of some colonial Chlamy- 

domonads. New Phytol., 17:151. 


Dangeard, P.: (1900) Observations sur la structure et le developpe- 

ment du Pandorina morum. Le Botaniste, 7:192. 
Doflein, F.: (1916) Polytomella agilis. Zool. Anz., 47:273. 
Dogiel, V.: (1935) Le mode de conjugaison de Polytoma uvella. 

Arch. zool. exper. gen., 77 (N. et R.) : 1:1. 
Elliott, A. M.: (1934) Morphology and life history of Haematococ- 

cus pluvialis. Arch. Protist., 82:250. 
Entz, G. Jr.: (1913) Cytologische Beobachtungen an Polytoma 

uvella. Verh. deutsch. zool. Ges. Ver. Berlin, 23:249. 
(1918) Ueber die mitotische Teilung von Polytoma uvella. 

Arch. Protist., 38:324. 
Fritsch, F. E.: (1935) The structure and reproduction of the algae. 
Geitler, L.: (1925) Zur Kenntnis der Gattung Pyramidoraonas. 

Arch. Protist., 52:356. 
Gerloff, J.: (1940) Beitrage zur Kenntnis der Variabilitat und 

Systematik der Gattung Chlamydomonas. Ibid., 94:311. 
Harper, R. A.: (1912) The structure and development of the colony 

in Gonium. Tr. Am. Micr. Soc, 31:65. 
Hartmann, M.: (1921) Untersuchungen iiber die Morphologie und 

Physiologie des Formwechsels der Phytomonadien. III. Arch. 

Protist., 43:223. 
— (1924) Ueber die Veranderung der Koloniebildung von 

Eudorina elegans und Gonium pectorale unter dem Einfluss aus- 

serer Bedingungen. IV. Ibid., 49:375. 
Hollande, A.: (1942) Etude cytologique et biologique de queleques 

flagelles libres. Arch. zool. exper. gen., 83:1. 
Janet, C.: (1912, 1922, 1923) Le Volvox. I. II and III Memoires. 

Kofoid, C. A.: (1900) Plankton studies. II, III. Ann. Mag. Nat, 
Hist., Ser. 7,6:139. 

Loefer, J. B.: (1935) Effect of certain carbohydrates and organic 
acids on growth of Chlorogonium and Cbilomonas. Arch Pro- 
tist., 84:456. 

( 1935a) Effect of certain nitrogen compounds on growth of 

Chlorogonium and Chilomonas. Ibid., 85:74. 

Luntz, A.: (1935) Ueber die Regulation der Reizbeantwortung bei 
koloniebildenden griinen Einzelligen. Ibid., 86:90. 

Mainx, F.: (1929) Ueber die Geschlechterverteilung bei Volvox 
aureus. Ibid., 67:205. 

Mast, S. O.: (1928) Structure and function of the eye-spot in uni- 
cellular and colonial organisms. Ibid., 60:197. 

Moewus, F.: (1932) Neue Chlamydomonaden. Ibid., 75:284. 

— (1933) Untersuchungen liber die Variabilitat von Chlamy- 
domonaden. Ibid., 80:128. 

— (1933a) Untersuchungen iiber die Sexualitat und Entwick- 
lung von Chlorophyceen. Ibid., 80:469. 

Pascher, A.: (1921) Neue oder wenig bekannte Protisten. Arch. 
Protist., 44:119. 

(1925) Neue oder wenig bekannte Protisten. XVII. Ibid., 51 : 



(1925a) XVIII. Ibid., 52:566. 

(1927) Volvocales — Phytomonadinae. Die Siisswasserflora. 

Pt. 4. 

— (1929) Neue oder wenig bekannte Protisten. Arch. Protist., 

— (1930) Neue Volvocalen. Ibid., 69:103. 

— (1932) Zur Kenntnis der einzelligen Volvocalen. Ibid., 76:1. 

— and Jahoda, Rosa: (1928) Neue Polyblepharidinen und 
Chlamydomonadinen aus den Almtumpeln um Lunz. Ibid., 

Pavillard, J.: (1952) Classe de Phytomonadines ou Volvocales. In: 

Grasse (1952), p. 154. 
Powers, J. H.: (1907) New forms of Volvox. Tr. Am. Micr. Soc, 


— (1908) Further studies in Volvox with descriptions of three 
new species. Ibid., 28: 141. 

Pringsheim, E. G.: (1930) Neue Chlamydomonadaceen, etc. Arch. 
Protist., 69:95. 

— (1937) Zur Kenntnis saprotropher Algen und Flagellaten. II. 
Ibid., 88:151. 

Reichenow, E.: (1909) Untersuchungen an Haematococcus pulvialis 

nebst Bemerkungen iiber andere Flagellaten. Arb. kaiserl. 

Gesundh., 33:1. 
Schiller, J.: (1925) Die planktonischen Vegetationen des adria- 

tischen Meeres. B. Arch. Protist., 53:59. 
Schulze, B.: (1927) Zur Kenntnis einiger Volvocales. Ibid., 58: 508. 
Shaw, W. R.: (1894) Pleodorina, a new genus of the Volvocideae. 

Bot. Gaz., 19:279. 
Skvortzow, B. W. : (1929) Einige neue und wenig bekannte Chlamy- 

domonadaceae aus Manchuria. Arch. Protist., 66:160. 
Smith, G. M.: (1944) A comparative study of the species of Volvox. 

Tr. Am. Micr. Soc, 63:265. 

(1950) The freshwater algae of the United States. New York. 

Swirenko: (1926) Ueber einige neue und interessante Volvocineae, 

etc. Arch. Protist., 55:191. 
Taft, C. E. : (1940) Asexual and sexual reproduction in Platydorina 

caudata. Tr. Am. Micr. Soc, 59:1. 
Tiffany. L. H.: (1935) Homothallism and other variations in 

Pleodorina calif ornica. Arch. Protist., 85:140. 
West, G. S. and Fritsch, F. E.: (1927) A treatise on the British 

freshwater algae. Cambridge. 

Chapter 11 
Order 4 Euglenoidina Blochmann 

THE body is as a rule elongated; some are plastic, others have a 
definite body form with a well-developed, striated or variously 
sculptured pellicle. At the anterior end, there is an opening through 
which a flagellum protrudes. In holophytic forms the so-called cyto- 
stome and cytopharynx, if present, are apparently not concerned with 
the food-taking, but seem to give a passage-way for the flagellum 
and also to excrete the waste fluid matters which become collected 
in one or more contractile vacuoles located near the reservoir. 
In holozoic forms, a well-developed cytostome and cytopharynx are 
present. Ordinarily there is only one flagellum, but some possess two 
or three. Chromatophores are present in the majority of the Eu- 
glenidae, but absent in two families. They are green, vary in 
shape, such as spheroidal, band-form, cup-form, discoidal, or 
fusiform, and usually possess pyrenoids. Some forms may contain 
haematochrome. A small but conspicuous stigma is invariably pres- 
ent near the anterior end of the body in chromatophore-bearing 

Reserve food material is the paramylon body, fat, and oil, the 
presence of which depends naturally on the metabolic condition 
of the organism. The paramylon body assumes diverse forms in dif- 
ferent species, but is, as a rule, constant in each species, and this 
facilitates specific identification to a certain extent. Nutrition is 
holophytic in chromatophore-possessing forms, which, however, 
may be saprozoic, depending on the amount of light and organic sub- 
stances present in the water. The holozoic forms feed upon bacteria, 
algae, and smaller Protozoa. 

The nucleus is, as a rule, large and distinct and contains almost 
always a large endosome. Asexual reproduction is by longitudinal 
fission; sexual reproduction has been observed in a few species. En- 
cystment is common. The majority inhabit fresh water, but some 
live in brackish or salt water, and a few are parasitic in animals. 
Taxonomy (Mainx, 1928; Hollande, 1942, 1952a); Jahn, 1946; Pring- 
sheim, 1950. 

With stigma Family 1 Euglenidae (p. 294) 

Without stigma 

With 1 flagellum Family 2 Astasiidae (p. 302) 

With 2 flagella Family 3 Anisonemidae (p. 303) 



Family 1 Euglenidae Stein 

Body plastic ("euglenoid"), but, as a rule, more or less spindle- 
form during locomotion. The flagellum arises from a blepharoplast 
located in the cytoplasm at the posterior margin of the reservoir. 
Between the blepharoplast and the "cytostome," the flagellum shows 
a swelling which appears to be photosensitive (Mast, 1938). Many 
observers consider that the basal portion of the flagellum is bifur- 
cated and ends in two blepharoplasts, but Hollande (1942), Prings- 
heim (1948) and others, hold that in addition to a long flagellum 
arising from a blepharoplast, there is present a short flagellum which 
does not extend beyond the neck of the reservoir and often adheres 
to the long flagellum, producing the appearance of bifurcation. Cul- 
ture and physiology (Mainx, 1928); cytology (Giinther, 1928; Hol- 
lande, 1942). 

Genus Euglena Ehrenberg. Short or elongated spindle, cylindrical, 
or band-form; pellicle usually marked by longitudinal or spiral 
striae; some with a thin pellicle highly plastic; others regularly spi- 
rally twisted; stigma usually anterior; chromatophores numerous and 
discoid, band-form, or fusiform; pyrenoids may or may not be sur- 
rounded by starch envelope; paramylon bodies which may be two 
in number, one being located on either side of nucleus, and rod-like 
to ovoid in shape or numerous and scattered throughout; contractile 
vacuole small, near reservoir; asexual reproduction by longitudinal 
fission; sexual reproduction reported in Euglena sanguined ; common 
in stagnant water, especially where algae occur; when present in 
large numbers, the active organisms may form a green film on the 
surface of water and resting or encysted stages may produce con- 
spicuous green spots on the bottom of pond or pool; in fresh water. 
Numerous species (Pascher, 1925; Johnson, 1944; Gojdics, 1953). 

E. pisciformis Klebs (Fig. 118, a). 20-35/* by 5-10/*; spindle-form 
with bluntly pointed anterior and sharply attenuated posterior end; 
slightly plastic; a body-length flagellum, active; 2-3 chromato- 
phores; division into two or four individuals in encysted stage 
(Johnson, 1944). 

E. viridis Ehrenberg (Fig. 118, 6). 40-65/* by 14-20/*; anterior end 
rounded, posterior end pointed; fusiform during locomotion; highly 
plastic when stationary; flagellum as long as the body; pellicle ob- 
liquely striated; chromatophores more or less bandform, radially 
arranged; nucleus posterior; nutrition holophytic, but also saprozoic. 
Multiplication in thin-walled cysts (Johnson). 

E. acus E. (Fig. 118, c). 50-175/* by 8-18/*; body long spindle or 



cylinder, with a sharply pointed posterior end; flagellum short, about 
I the body length; spiral striation of pellicle very delicate; numerous 
discoid chromatophores; several paramylon bodies, rod-form and 
12-20ju long; nucleus central; stigma distinct; movement sluggish. 

Fig. 118. Species of Euglena (Johnson), a, Euglena pisciformis, X855; 
b, E. viridis, X400; c, E. acus, X555; d, E. spirogyra, X460; e, E. oxyuris, 
X200; f, E. sanguinea, X400; g, E. deses, X315; h, E. gracilis, X865; i, 
E. tripteris, with optical section of body, X345; j, E. ehrenbergi, X145; 
k, E. terricola, X345; 1, E. sociabilis, X320; m, two individuals of E. 
klebsi, X335; n, two individuals of E. rubra, X355. 

E. spirogyra E. (Fig. 118, d). 80-125 ;u by 10-35m; cylindrical; an- 
terior end a little narrowed and rounded, posterior end drawn out; 
spiral striae, made up of small knobs, conspicuous; many discoid 
chromatophores; two ovoidal paramylon bodies, 18-45/x by 10-18/x, 
one on either side of centrally located nucleus; flagellum about \ the 
body length; stigma prominent; sluggish. 

E. oxyuris Schmarda (Fig. 118, e). 1 50-500 m by 20-40^; cylindri- 


cal; almost always twisted, somewhat flattened; anterior end round- 
ed, posterior end pointed; pellicle with spiral striae; numerous dis- 
coid chromatophores; two ovoid paramylon bodies, 20-40/* long, one 
on either side of nucleus, and also small bodies; stigma large; flagel- 
lum short; sluggish. 

E. sanguinea E. (Fig. 118,/). 80-170/* by 25-45/*; posterior end 
bluntly rounded; flagellum about the body length; pellicle striated; 
elongate chromatophores lie parallel to the striae; haematochrome 
granules scattered in sun light and collected in the central area in 

E. deses E. (Fig. 118, g). 85-170/* by 10-20/*; elongate; highly 
plastic; faint striae; stigma distinct; nucleus central; chromato- 
phores discoid with pyrenoid; several small rod-shaped paramylon 
scattered; flagellum less than \ the body length. 

E. gracilis Klebs (Fig. 118, h). 35-55/* by 6-25/*; cylindrical to 
elongate oval; highly plastic; flagellum about the body length; fusi- 
form chromatophores 10-20; nucleus central; pyrenoids. 

E. tripteris Dujardin (Fig. 118, i). 70-120/* by 12-16/*; elongate; 
three-ridged, rounded anteriorly and drawn out posteriorly; pellicle 
longitudinally striated; only slightly plastic; stigma prominent; dis- 
coid chromatophores numerous; two paramylon bodies, rod-shaped 
and one on either side of the nucleus; flagellum about f the body 

E. ehrenbergi Klebs (Fig. 118, j). 170-400/* by 15-40/*; cylindrical 
and flattened, posterior end rounded; plastic, often twisted; spiral 
striation; numerous small discoid chromatophores; stigma conspicu- 
ous; 2 paramylon bodies elongate, up to over 100m long; flagellum 
about \ the body length or less. 

E. terricola Dangeard (Fig. 118, k). 65-95/* by 8-18/*; pellicle thin 
and highly plastic; nucleus central; chromatophores long (20-30/*) 
rods; paramylon bodies small and annular; flagellum about § the 
body length. 

E. sociabilis D. (Fig. 118, 1). 65-112/* by 15-30/*; cylindrical; deli- 
cate pellicle; highly plastic; numerous elongate chromatophores; 
paramylon bodies discoid; flagellum slightly longer than body. 

E. klebsi Mainx (Fig. 118, m). 45-85/* by 5-10/*; form highly 
plastic; chromatophores discoid; paramylon bodies rod-shaped, up 
to several; flagellum short. 

E. rubra Hardy (Fig. 118, n). 70-170/* by 25-36/*; cylindrical; 
rounded anteriorly and drawn out posteriorly; spiral striation; nu- 
cleus posterior; flagellum longer than body; stigma about 7/* in di- 
ameter; many fusiform chromatophores aligned with the body striae; 


numerous haematochrome granules, 0.3-0.5/x in diameter: ovoid 
paramylon bodies; reproductive and temporary cysts and protective 
cysts, 34-47^ in diameter, with a gelatinous envelope. 

Johnson (1939) found that the color of this Euglena was red in 
the morning and dull green in the late afternoon, due to the dif- 
ference in the distribution of haematochrome within the body. 
When haematochrome granules are distributed throughout the 
body, the organism is bright-red, but when they are condensed 
in the center of the body, the organism is dull green. When part 
of the area of the pond was shaded with a board early in the 
morning, shortly after sunrise all the scum became red except 
the shaded area. When the board was removed, the red color 
appeared in 11 minutes while the temperature of the water remained 
21°C. In the evening the change was reversed. Johnson and Jahn 
(1942) later found that green-red color change could be induced by 
raising the temperature of the water to 30-40°C. and by irradiation 
with infrared rays or visible light. The two workers hold that the 
function of haematochrome may be protective, since it migrates to a 
position which shields the chromatophores from very bright light. 
If this is true, it is easy to find the species thriving in hot weather in 
shallow ponds where temperature of the water rises to 35-45°C. In 
colder weather, it is supposed that this Euglena is less abundant and 
it exists in a green phase, containing a few haematochrome granules. 

Genus Khawkinea Jahn and McKibben. Similar to Genus Eu- 
glena, but without chromatophores and thus permanently colorless ; 
fresh water. 

K. halli.L and M. 30-65/z by 12-14/*; fusiform; pellicle spirally 
striated; plastic; flagellum slightly longer than body; stigma 2-3/x in 
diameter, yellow-orange to reddish-orange, composed of many gran- 
ules; numerous (25-100) paramylon bodies elliptical or polyhedral: 
cysts 20-30^ in diameter; putrid leaf infusion; saprozoic (Jahn and 
McKibben, 1937). 

K. ocellata (Khawkine). Similar to above; flagellum 1.5-2 times 
body length; fresh water. 

Genus Phacus Dujardin. Highly flattened; asymmetrical; pellicle 
firm; body form constant; prominent longitudinal or oblique stria- 
tion; flagellum and a stigma; chromatophores without pyrenoid 
(Pringsheim) are discoid and green; holophytic ; fresh water. Numer- 
ous species (Skvortzov, 1937; Pochmann, 1942; Conrad, 1943; Alle- 
gre and Jahn, 1943); Morphology and cytology (Krichenbauer, 1937; 
Conrad, 1943). 

P. pleuronectes (Miiller) (Fig. 119, a). 45-100 n by 30-70/x; short 



posterior prolongation slightly curved; a prominent ridge on the con- 
vex side, extending to posterior end; longitudinally striated; usually 
one circular paramylon body near center; flagellum as long as body. 
P. longicauda (Ehrenberg) (Fig. 119, b). 120-170/* by 45-70/*; 
usually slightly twisted ; a long caudal prolongation ; flagellum about 

Fig. 119. Species of Phacus (Allegre and Jahn). a, Phacus pleuronedes 
and an end view, X800; b, P. longicauda, X500; c, P. pyrum and an end 
view, X880; d, P. acuminata and an end view, XI 300; e, P. monilata, 
X800; f, P. torta, and an end view, X800; g, P. oscillans, X1400. 

one discoidal paramylon body central; pellicle longitudinally stri- 

P. pyrum (E.) (Fig. 119, c). About 30-50/1 by 10-20/*; circular in 
cross-section; with a medium long caudal prolongation; pellicle ob- 
liquely ridged; stigma inconspicuous; two discoid paramylon bodies; 
flagellum as long as the body. 


P. acuminata Stokes (Fig. 119, d). About 30-40 m by 20-30/*; 
nearly circular in outline; longitudinally striated; usually one small 
paramylon body; flagellum as long as the body. 

P. monilata (S) (Fig. 119, e). 40-55/z by 32-40/*; a short caudal pro- 
jection; pellicle with minute knobs arranged in longitudinal rows; 
discoid chromatophores; flagellum about the body length. 

P. torta Lemmermann (Fig. 119, /). 80-100 m by 40-45/*; body 
twisted, with a long caudal prolongation; longitudinal striae on pel- 
licle; chromatophores discoid; one large circular paramylon body; 
flagellum about | the body length. 

P. oscillans Klebs (Fig. 119, g). 15-35/* by 7-10/x; rounded ante- 
riorly and bluntly pointed posteriorly; striation oblique; 1 or 2 
paramylon bodies; flagellum about as long as the body. 

Genus Lepocinclis Perty (Crumenula Dujardin). Body more or 
less ovo-cylindrical; rigid with spirally striated pellicle; often with a 
short posterior spinous projection; stigma sometimes present; dis- 
coidal chromatophores numerous and marginal; paramylon bodies 
usually large and ring-shaped, laterally disposed; without pyrenoids; 
fresh water. Many species (Pascher, 1925, 1929: Conrad, 1934; 
Skvortzov, 1937). 

L. ovum (Ehrenberg) (Fig. 120, a). Body 20-40 /x long. 

Genus Trachelomonas Ehrenberg. With a lorica which often pos- 
sesses numerous spines; sometimes yellowish to dark brown, com- 
posed of ferric hydroxide impregnated with a brown manganic com- 
pound (Pringsheim, 1948); a single long flagellum protrudes from 
the anterior aperture, the rim of which is frequently thickened to 
form a collar; chromatophores either two curved plates or numerous 
discs; paramylon bodies small grains; a stigma and pyrenoid; mul- 
tiplication by fission, one daughter individual retains the lorica and 
flagellum, while the other escapes and forms a new one; cysts com- 
mon; fresh water. Numerous species (Palmer, 1902, 1905, 1925, 
1925a; Pascher, 1924, 1925, 1925a, 1926, 1929; Gordienko, 1929; 
Conrad, 1932; Skvortzov, 1937; Balech, 1944). 

T. hispida (Perty) (Figs. 32, a; 120, b). Lorica oval, with numerous 
minute spines; brownish; 8-10 chromatophores; 20-42 /i by 15-26/t; 
many varieties. 

T. urceolata Stokes (Fig. 120, c). Lorica vasiform, smooth with a 
short neck; about 45/z long. 

T. piscatoris (Fisher) (Fig. 120, d). Lorica cylindrical with a short 
neck and with numerous short, conical spines; 25-40/z long; flagel- 
lum 1-2 times body length. 



T. verrucosa Stokes (Fig. 120, e). Lorica spherical, with numerous 
knob-like attachments ; no neck ; 24-25/* in diameter. 

T. vermiculosa Palmer (Fig. 120, /). Lorica spherical; with many 
sausage-form markings; 23m in diameter. 

Genus Cryptoglena Ehrenberg. Body rigid, flattened; 2 band-form 
chromatophores lateral; a single flagellum; nucleus posterior; 
among freshwater algae. One species. 

C. pigra E. (Fig. 120, g). Ovoid, pointed posteriorly; flagellum 
short; stigma prominent; 10-15/t by 6-10/t; standing water. 

y£f+;£$$ I'/Jf If] 


Fig. 120. a, Lepocinclis ovum, X430 (Stein); b, Trachelomonas hispida, 
X430 (Stein); c, T. urceolata, X430 (Stokes); d, T. piscatoris, X520 
(Fisher); e, T. verrucosa, X550 (Stokes); f, T. vermiculosa, X800 (Palmer); 
g, Cryptoglena pigra, X430 (Stein); h, Ascoglena vaginicola, X390 (Stein); 
i, Eutreptia viridis, X270 (Klebs); j, E. marina, X670 (da Cunha); k, 
Euglenamorpha hegneri, X730 (Wenrich). 

Genus Ascoglena Stein. Encased in a flexible, colorless to brown 
lorica, attached with its base to foreign object; solitary; without 
stalk; body ovoidal, plastic; attached to test with its posterior end; 
a single flagellum; a stigma; numerous chromatophores discoid; 
with or without pyrenoids; reproduction as in Trachelomonas; 
fresh water. 

A. vaginicola S. (Fig. 120, h). Lorica about 43/i by 15/*. 

Genus Colacium Ehrenberg. Stalked individuals form colony; 
frequently attached to animals such as copepods, rotifers, etc. ; stalk 
mucilaginous; individual cells pyriform, ellipsoidal or cylindrical; 
without flagellum; a single flagellum only in free-swimming stage; 
disco idal chromatophores numerous; with pyrenoids; multiplication 



by longitudinal fission; also by swarmers, possessing a flagellum and 
a stigma; fresh water. Several species. 

C. vesiculosum E. (Fig. 121). Solitary or colonial, made up of two 
to eight individuals; flagellate form ovoid to spindle; 22 ju by 12^; 
seven to ten elongate chromatophores along the periphery; flagellum 

Fig. 121. Colacium vesiculosum (Johnson), a, diagram showing the life 
cycle (a-d, palmella stage; e, formation of flagellate stage; f, formation 
of flagellate stage by budding of Palmella stage; g, flagellate stage; h, 
attached stage); b, flagellate and c, stalked form on a crustacean, X1840. 

one to two times the body length; a stigma; many paramylon bodies; 
palmella stage conspicuous; stalked form (Johnson, 1934). 

Genus Eutreptia Perty (Eutreptiella da Cunha). With 2 flagella at 
anterior end; pellicle distinctly striated; plastic; spindle-shaped dur- 
ing movement; stigma; numerous discoid chromatophores; pyren- 
oids absent; paramylon bodies spherical or subcylindrical ; multipli- 
cation as in Euglena; cyst with a thick stratified wall; fresh or salt 

E. viridis P. (Fig. 120, i). 50-70 M by 5-13;u; in fresh water; a 
variety was reported from brackish water ponds. 

E. marina (da Cunha) (Fig. 120, j). Flagella unequal in length; 



longer one as long as body, shorter one ^; body 40-50/* by 8-10/*; 
salt water. 

Genus Euglenamorpha Wenrich. Body form and structure similar 
to those of Euglena, but with 3 flagella; in gut of frog tadpoles. One 

E. hegneri W. (Fig. 120, k). 40-50/* long (Wenrich, 1924). 

Family 2 Astasiidae Butschli 

Similar to Euglenidae in body form and general structure, but 
without chromatophores; body highly plastic, although usually 
elongate spindle. 

Genus Astasia Dujardin. Body plastic, although ordinarily elon- 
gate; fresh water or parasitic (?) in microcrustaceans. Many species 
(Pringsheim, 1942). Bacteria-free cultivation (Schoenborn, 1946). 

A. klebsi Lemmermann (Fig. 122, a). Spindle-form; posterior 

Fig. 122. a, Astasia klebsi, X500 (Klebs); b, Urceolus cyclostomus, 
X430 (Stein); c, U. sabulosus, X430 (Stokes); d, Petalomonas mediocanel- 
lata, X1000 (Klebs); e, Rhabdomonas incurva, X1400 (Hall); f, Scyto- 
monas pusilla, X430 (Stein). 

portion drawn out; flagellum as long as body; plastic; paramylon 
bodies oval; 40-50/* by 13-20/*; stagnant water. 

Genus Urceolus Mereschkowsky (Phialonema Stein). Body color- 
less; plastic; flask-shaped; striated; a funnel-like neck; posterior 
region stout; a single flagellum protrudes from funnel and reaches in- 
ward the posterior third of body; fresh or salt water. 

U. cyclostomus (Stein) (Fig. 122, b). 25-50/* long; fresh water. 

U. sabulosus (Stokes) (Fig. 122, c). Spindle-form; covered with 
minute sand-grains; about 58/* long; fresh water. 

Genus Petalomonas Stein. Oval or pyriform; not plastic; pellicle 
often with straight or spiral furrows; a single flagellum; paramylon 


bodies; a nucleus; holozoic or saprozoic. Many species in fresh water 
and a few in salt water. Species (Shawhan and Jahn, 1947). 

P. mediocanellata S. (Fig. 122, d). Ovoid with longitudinal fur- 
rows on two sides; flageHum about as long as the body; 21-26/x long. 

Genus Rhabdomonas Fresenius. Rigid body, cylindrical and not 
flattened, more or less arched ; pellicle longitudinally ridged ; a flag- 
ellum through aperture at the anterior tip; fresh water (Pringsheim, 
1942). Species (Pascher, 1925); relation to Menoidium (Pringsheim, 

R. incurva F. (Figs. 69, 122, e). Banana-shaped; longitudinal ridges 
conspicuous; flagellum as long as the body; 15-25^ by 7-8 n (Hall, 
1923); 13-15/x by 5-7;u (Hollande, 1952a); common in standing 

Genus Scytomonas Stein. Oval or pyriform, with a delicate pel- 
licle; a single flagellum; a contractile vacuole with a reservoir; 
holozoic on bacteria; longitudinal fission in motile stage; stagnant 
water and coprozoic. 

S. pusilla S. (Fig. 122, /). About 15/x long. Cytology (Schiissler, 

Genus Copromonas Dobell. Elongate ovoid; with a single flagel- 
lum; a small cytostome at anterior end; holozoic on bacteria; per- 
manent fusion followed by encystment (p. 183); coprozoic in faecal 
matters of frog, toad, and man; several authors hold that this genus 
is probably identical with Scytomonas which was incompletely de- 
scribed by Stein. 

C. subtilis D. (Fig. 78). 7-20ju long. Golgi body (Gatenby and 
Singh, 1938). 

Family 3 Anisonemidae Schewiakoff 

Colorless body plastic or rigid with a variously marked pellicle; 
2 flagella, one directed anteriorly and the other usually posteriorly; 
contractile vacuoles and reservoir; stigma absent; paramylon bodies 
usually present; free-swimming or creeping. 

Genus Anisonema Dujardin. Generally ovoid; more or less flat- 
tened; asymmetrical; plastic or rigid; a slit-like ventral furrow; 
flagella at anterior end; cytopharynx long; contractile vacuole an- 
terior; nucleus posterior; in fresh water. Several species. 

A. acinus D. (Fig. 123, a). Rigid; oval; somewhat flattened; pel- 
licle slightly striated; 25-40m by 16-22/x. 

A. truncatum Stein (Fig. 123, b). Rigid; elongate ovoid: 60 m by 

A. emarginatum Stokes (Fig. 123, c). Rigid; 14/x long; flagella long. 


Genus Peranema Dujardin. Elongate, with a broad rounded or 
truncate posterior end during locomotion; highly plastic when sta- 
tionary; delicate pellicle shows a fine striation; expansible cytostome 
with a thickened ridge and two oral rods at anterior end; aperture 
through which the flagella protrude is also at anterior end; a free 
flagellum, long and conspicuous, tapers toward free end; a second 
flagellum adheres to the pellicle; nucleus central; a contractile vacu- 
ole, anterior, close to the reservoir; holozoic; fresh water. 

P. trichophorum (Ehrenberg) (Fig. 123, d). 4.0-70/x long; body or- 
dinarily filled with paramylon or starch grains derived from Astasia, 
Rhabdomonas, Euglena, etc., which coinhabit the culture; holozoic; 
very common in stagnant water. Cell inclusion (Hall, 1929); struc- 
ture and behavior (Chen, 1950); development (Lackey, 1929); flag- 
ellar apparatus (Lackey, 1933; Pitelka, 1945); food intake (Hall, 
1933; Hollande, 1942; Hyman, 1936; Chen, 1950). 

P. granulifera Penard. Much smaller in size. 8-1 5ju long; elongate, 
but plastic; pellicle granulated; standing water. 

Genus Heteronema Dujardin. Plastic; rounded or elongate; 
flagella arise from anterior end, one directed forward and the other 
trailing; cytostome near base of flagella; holozoic; fresh water. Sev- 
eral species. 

H. acus (Ehrenberg) (Fig. 123, e). Extended body tapers towards 
both ends; anterior flagellum as long as body, trailing one about 1/2; 
contractile vacuole anterior ; nucleus central ; 45-50/* long ; fresh water. 
Morphology, reproduction (Loefer, 1931). 

H. mutabile (Stokes) (Fig. 123,/). Elongate; highly plastic ; longi- 
tudinally striated; about 254/x long; in cypress swamp. 

Genus Tropidoscyphus Stein. Slightly plastic; pellicle with 8 
longitudinal ridges; 2 unequal flagella at anterior pole; holozoic or 
saprozoic; fresh or salt water. 

T. octocostatus S. (Fig. 123, g). 35-63yu long; fresh water, rich in 

Genus Distigma Ehrenberg. Plastic; elongate when extended; 
body surface without any marking; 2 flagella unequal in length, di- 
rected forward; cytostome and cytopharynx located at anterior end; 
endoplasm usually transparent; holozoic. Several species (Prings- 
heim, 1942). 

D. proteus E. (Fig. 123, h). 50-1 10m long when extended; nucleus 
central; stagnant water; infusion. Cytology (Hollande, 1937). 

Genus Entosiphon Stein. Oval, flattened; more or less rigid,; 
flagella arise from a cytostome, one flagellum trailing; protrusible 
cytopharynx a long conical tubule almost reaching posterior end; 



nucleus centro-lateral; fresh water. 

E. sulcatum (Dujardin) (Fig. 123, i). About 20/i long (Lackey, 
1929, 1929a). 

E. ovatum Stokes. Anterior end rounded; 10-12 longitudinal 
striae; about 25-28/z long. 

Genus Notosolenus Stokes. Free-swimming; rigid oval; ventral 

Fig. 123. a, Anisonema acinus, X400 (Klebs); b, A. truncatum, X430 
(Stein); c, A. emerginatum, X530 (Stokes); d, Peranema trichophorum, 
X670; e, Heteronema acus, X430 (Stein); f, H. mutabile, XI 20 (Stokes); 
g, Tropidoscyphus octocostatus, X290 (Lemmermann); h, Distigma proteus, 
X430 (Stein); i, Entosiphon sulcatum, X430 (Stein); j, Notosolenus apo- 
camptus, X120 (Stokes); k, N. sinuatus, X600 (Stokes); 1, m, front and 
side views of Triangulomonas rigida, X935 (Lackey); n, Marsupiogaster 
striata, X590 (Schewiakoff ) ; o, M. picta (Faria, da Cunha and Pinto). 


surface convex, dorsal surface with a broad longitudinal groove; 
flagella anterior; one long, directed anteriorly and vibratile; the 
other shorter and trailing; fresh water with vegetation. 

iV. apocamptus S. (Fig. 123, j). Oval with broad posterior end; 
6-1 1/x long. 

N. sinuatus S. (Fig. 123, h). Posterior end truncate or concave; 
about 22/t long. 

Genus Triangulomonas Lackey. Rigid body, triangular, with con- 
vex sides; one surface flat, the other elevated near the anterior end; 
pellicle brownish; a mouth at anterior end with cytopharynx and 
reservoir: two flagella, one trailing; salt water. 

T. rigida L. (Fig. 123, I, m). Body 18m by 15/z; anterior flagellum 
as long as the body; posterior flagellum 1.5 times the body length; 
Woods Hole (Lackey, 1940). 

Genus Marsupiogaster Schewiakoff. Oval; flattened; asymmet- 
rical; cytostome occupies entire anterior end; cytopharynx con- 
spicuous, 1/2 body length; body longitudinally striated; 2 flagella, 
one directed anteriorly, the other posteriorly; spherical nucleus; 
contractile vacuole anterior; fresh or salt water. 

M. striata Schewiakoff (Fig. 123, n). About 27/x by 15/x; fresh 
water; Hawaii. 

M . picta Faria, da Cunha and Pinto (Fig. 123, o). In salt water; 
Rio de Janeiro. 

Order 5 Chloromonadina Klebs 

The chloromonads are of rare occurrence and consequently not 
well known. The majority possess small discoidal grass-green chro- 
matophores with a large amount of xanthophyll which on addition 
of an acid become blue-green. No pyrenoids occur. The metabolic 
products are fatty oil. Starch or allied carbohydrates are absent. 
Stigma is also not present. Genera (Poisson and Hollande, 1943; Hol- 
lande, 1952). 

Genus Gonyostomum Diesing (Rhaphidomonas Stein). With a sin- 
gle flagellum: chromatophores grass-green; highly refractile tricho- 
cyst-like bodies in cytoplasm ; fresh water. A few species. 

G. semen D. (Fig. 124, a). Sluggish animal; about 45-60/x long; 
among decaying vegetation. 

Genus Vacuolaria Cienkowski (Coelomonas Stein). Highly plastic; 
without trichocyst-like structures; anterior end narrow; two flag- 
ella; cyst with a gelatinous envelope. One species. 

V. virescens C. (Fig. 124, 6). 50-70 M by 18-25/*; fresh water. Cy- 
tology (Fott, 1935; Poisson and Hollande, 1943). 



Genus Trentonia Stokes. Bi-flagellate as in the last genus; but 
flattened; anterior margin slightly bilobed. One species. 

T. flagellata S. (Fig. 124, c). Slow-moving organism; encystment 
followed by binary fission; about 60ju long; fresh water. 

Genus Thaumatomastix Lauterborn. Colorless; pseudo podia 
formed; 2 flagella, one extended anteriorly, the other trailing; holo- 

Fig. 124. a, Gonyostomum semen, X540 (Stein); b, Vacuolaria virescens, 
X460 (Senn); c, Trentonia flagellata, X330 (Stokes); d, Thaumatomastix 
setifera, X830 (Lauterborn) 

zoic; perhaps a transitional form between the Mastigophora and the 
Sarcodina. One species. 

T. setifera L. (Fig. 104, d). About 20-35/* by 15-28/*; fresh water. 


Allegre, C. F. and Jahn, T. L.: (1943) A survey of the genus 

Phacus Dujardin. Tr. Am. Micr. Soc, 62:233. 
Balech, E.: (1944) Trachelomonas de la Argentina. An. Mus. 

Argent. Cien. Nat., 41:221. 
Chen, Y. T.: (1950) Investigations of the biology of Peranema tri- 

chophorum. Quart. J. Micr. Sc, 91:279. 
Conrad, W.: (1932) Flagellates nouveaux ou peu connus. III. Arch. 

Protist., 78:463. 
(1934) Materiaux pour une monographic du genre Lepo- 

cinclis. Ibid., 82:203. 

(1943) Notes protistologiques. XXVIII. Bull. Mus. Roy. 

d'Hist. Natur. Belgique, 19, no. 6. 
da Cunha, A. M.: (1913) Sobre um novo genero de "Euglenoidea." 
Brazil Medico, 27:213. 


Dangeard, P.: (1901) Recherches sur les Eugleniens. La Bot., 8:97. 
Fott, B.: (1935) Ueber den inneren Bau von Vacuolaria viridis. 

Arch. Protist., 84:242. 
Fritsch, F. E.: (1935) The structure and reproduction of the algae. 
Gatenby, J. B. and Singh, B. N.: (1938) The Golgi apparatus of 

Copromonas subtilis and Euglena sp. Quart. J. Micr. Sc., 80:567. 
Gojdics, Mary: (1953) The genus Euglena. Madison, Wisconsin. 
Gordienko, M.: (1929) Zur Frage der Systematik der Gattung 

Trachelomonas. Arch. Protist., 65:258. 
Gunther, F.: (1928) Ueber den Bau und die Lebensweise der 

Euglenen, etc. Ibid., 60:511. 
Hall, R. P.: (1923) Morphology and binary fission of Menoidium 

incurvum. Univ. California Publ. Zool., 20:447. 
(1929) Reaction of certain cytoplasmic inclusions to vital 

dyes and their relation to mitochondria and Golgi apparatus in 

the flagellate Peranema trichophorum. J. Morphol. Physiol., 48: 

(1933) The method of ingestion in Peranema, etc. Arch. 

Protist., 81:308. 
(1934) A note on the flagellar apparatus of Peranema, etc. 

Tr. Am. Micr. Soc, 53:237. 

(1937) A note on behavior of chromosomes. Ibid., 56:288. 

Hollande, A.: (1937) Quelques donnees nouvelles sur la cytologic 

d'une Astasiacee peu connu: Distigma proteus. Bull. Soc. zool. 

Fr., 62:236. 
(1942) Etudes cytologique et biologique de quelques flagelles 

libres. Arch. zool. exp. gen., 83:1. 

— (1952) Classe de Chloromonadines. In: Grasse (1952), p. 227. 

— (1952a) Classe des Eugleniens. Ibid., p. 239. 

Hyman, Libbie H.: (1936) Observations on Protozoa. II. Quart. J. 

Micr. Sc. 79:50,. 
Jahn, T. L.: (1946) The euglenoid flagellates. Quart. Rev. Biol., 21: 


— and McKibben, W. R.: (1937) A colorless euglenoid flagel- 
late, Khawkinea halli n.g., n.sp. Tr. Am. Micr. Soc, 56:48. 

Johnson, D. F. : (1934) Morphology and life history of Colacium 

vesiculosum. Arch. Protist., 83:241. 
Johnson, L. P.: (1939) A study of Euglena rubra. Tr. Am. Micr. 

Soc, 58:42. 

(1944) Euglena of Iowa. Ibid., 63:97. 

and Jahn, T. L. : (1942) Cause of the green-red color change 

in Euglena rubra. Physiol. Zool, 15:89. 
Krichenbauer, H.: (1937) Beitrag zur Kenntnis der Morphologie 

und Entwicklungsgeschichte der Gattungen Euglena und Pha- 

cus. Arch. Protist., 90:88. 
Lackey, J. B.: (1929) Studies on the life history of Euglenida. I. 

Ibid., 66:175. 

(1929a) II. Ibid., 67:128. 

(1933) III. Biol. Bull., 65:238. 


(1940) Some new flagellates from the Woods Hole area. Am. 

Midi. Nat., 23:463. 
Lemmermann, E.: (1913) Eugleninae. Siisswasserflora Deutsch- 

lands. Pt. 2. 
Loefer, J. B.: (1931) Morphology and binary fission of Heteronema 

acus. Arch. Protist., 74:449. 
Mainx, F. : (1928) Beitrage zur Morpholgie und Physiologie der 

Eugleninen. I, II. Ibid., 60:305. 
Palmer, T. C: (1902) Five new species of Trachelomonas. Proc. 

Acad. Nat. Sc., Philadelphia, 54:791. 

(1905) Delaware valley forms of Trachelomonas. Ibid., 57:665. 

(1925) Trachelomonas: etc. Ibid., 77:15. 

(1925a) Nomenclature of Trachelomonas. Ibid., 77:185. 

Pascher, A.: (1913) Chloromonadinae. Siisswasserflora Deutsch. 

Pt. 2. 
(1924) Neue oder wenig bekannte Protisten. XIII. Arch. 

Protist., 48:492. 

(1925) XV. Ibid., 50:486. 

(1925a) XVII. Ibid., 51:549. 

(1926) XIX. Ibid., 53:459. 

(1929) XXI. Ibid., 65:426. 

Pitelka, Dorothy R. : (1945) Morphology and taxonomy of flagel- 
lates of the genus Peranema Dujardin. J. Morphol., 76: 179. 

Pochmann, A.: (1942) Synopsis der Gattung Phacus. Arch. Protist., 

Poisson, R. and Hollande, A.: (1943) Considerations sur la cy- 
tologic, la mitose et les affinit^s des Chloromonadies. Ann. Sc. 
Nat. Ser. Bot. Zool., 5:147. 

Pringsheim, E. G.: (1942) Contribution to our knowledge of sapro- 
phytic Algae and Flagellata. III. New Phytologist, 41:171. 

(1948) Taxonomic problems in the Euglenineae. Biol. Rev., 


and Hovasse, R. : (1948) The loss of chromatophores in 

Euglena gracilis. New Phytologist, 47:52. 

(1950) Les relations de parente entre Astasiacees et 

Euglenacees. Arch. zool. exper. gen., 86:499. 
Schoenborn, H. W. : (1946) Studies on the nutrition of colorless 

euglenoid flagellates. II. Physiol. Zool., 19:430. 
Schussler, H.: (1917) Cytologische und entwicklungsgeschichtliche 

Protozoenstudien. I. Arch. Protist., 38:117. 
Shawhan, Fae M. and Jahn, T. L.: (1947) A survey of the genus 

Petalomonas. Tr. Am. Micr. Soc, 66:182. 
Skvortzov, B. V.: (1937) Contributions to our knowledge of the 

freshwater algae of Rangoon, Burma, India. I. Arch. Protist., 

Stokes, A. C: (1888) A preliminary contribution toward a history 

of the freshwater Infusoria of the United States. J. Trenton Nat. 

Hist. Soc, 1:71. 

Chapter 12 
Order 6 Dinoflagellata Biitschli 

THE dinoflagellates make one of the most distinct groups of the 
Mastigophora, inhabiting mostly marine water, and to a lesser 
extent fresh water. In the general appearance, the arrangement of 
the two flagella, the characteristic furrows, and the possession of 
brown chromatophores, they are closely related to the Crypto- 

The body is covered by an envelope composed of cellulose which 
may be a simple smooth piece, or may be composed of two valves 
or of numerous plates, that are variously sculptured and possess 
manifold projections. Differences in the position and course of the 
furrows and in the projections of the envelope produce numerous 
asymmetrical forms. The furrows, or grooves, are a transverse an- 
nulus and a longitudinal sulcus. The annulus is a girdle around the 
middle or toward one end of the body. It may be a complete, 
incomplete or sometimes spiral ring. While the majority show a 
single transverse furrow, a few may possess several. The part of the 
shell anterior to the annulus is called the epitheca and that posterior 
to the annulus the hypotheca. In case the envelope is not developed, 
the terms epicone and hypocone are used (Fig. 105). The sulcus 
may run from end to end or from one end to the annulus. The two 
flagella arise typically from the furrows, one being transverse and 
the other longitudinal. 

The transverse flagellum which is often band-form, encircles the 
body and undergoes undulating movements, which in former years 
were looked upon as ciliary movements (hence the name Cilioflagel- 
lata). In the suborder Prorocentrinea, this flagellum vibrates freely 
in a circle near the anterior end. The longitudinal flagellum often 
projects beyond the body and vibrates. Combination of the move- 
ments of these flagella produces whirling movements characteristic 
of the organisms. 

The majority of dinoflagellates possess a single somewhat massive 
nucleus with evenly scattered chromatin, and usually several endo- 
somes. There are two kinds of vacuoles. One is often surrounded by 
a ring of smaller vacuoles, while the other is large, contains pink- 
colored fluid and connected with the exterior by a canal opening into 
a flagellar pore. The latter is known as the pusule which functions 
as a digestive organella (Kofoid and Swezy). In many freshwater 
forms a stigma is present, and in Pouchetiidae there is an ocellus 
composed of an amyloid lens and a dark pigment-ball. The majority 



of planktonic forms possess a large number of small chromatophores 
which are usually dark yellow, brown or sometimes slightly greenish 
and are located in the periphery of the body, while bottom-dwelling 
and parasitic forms are, as a rule, colorless, because of the absence of 
chromatophores. A few forms contain haematochrome. The method 
of nutrition is holophytic, holozoic, saprozoic, or mixotrophic. In 
holophytic forms, anabolic products are starch, oil, or fats. 

Anterior flagellar pore n. /" -\ -Epicone 

}■£ \ ^Transverse flagellum 

Annulus or girdle - — Ls^^^^^^^ 

^C \\ 4 Sulcus 

Hypocone V— ][r^>j/ 

Longitudinal flagellum - — j ^Posterior flagellar pore 

Fig. 125. Diagram of a typical naked dinoflagellate (Lebour). 

Asexual reproduction is hy binary or multiple fission or budding 
in either the active or the resting stage and differs among different 
groups. Encystment is of common occurrence. In some forms the 
cyst wall is formed within the test. The cysts remain alive for many 
years; for example, Ceratium cysts were found to retain their vital- 
ity in one instance for six and one-half years. Conjugation and sexual 
fusion have been reported in certain forms, but definite knowledge on 
sexual reproduction awaits further investigation. 

The dinoflagellates are abundant in the plankton of the sea and 
play an important part in the economy of marine life as a whole. A 
number of parasitic forms are also known. Their hosts include vari- 
ous diatoms, copepods and several pelagic animals. 

Some dinoflagellates inhabiting various seas multiply suddenly in 
enormous numbers within certain areas, and bring about distinct 
discolorations of water, often referred to as "red tide" or "red wa- 
ter." Occasionally the red water causes the death of a large number 
of fishes and of various invertebrates. According to Galtsoff (1948, 
1949), the red water which appeared on the west coast of Florida 
in 1946 and 1947, was due to the presence of an enormous number 
of Gymnodinium brevis and this dinoflagellate seemed in some man- 
ner to have been closely correlated with the fatal effect on animals 
entering the discolored water. Ketchum and Keen (1948) found the 
total phosphorus content of the water containing dense Gymnodin- 
ium populations to be 2.5 to 10 times the maximum expected in 


the sea, and the substance associated with Gymnodinium and other 
dinoflagellates causes nose and throat irritations in man. Woodcock 
(1948) observed that similar irritations can be produced by breath- 
ing air artificially laden with small drops of the red water contain- 
ing 56X10 6 dinoflagellates per liter. The irritant substance passed 
through a fine bacterial filter, and was found to be very stable, re- 
maining active in stored red water for several weeks. Distribution 
and taxonomy (Kofoid, 1906, 1907, 1909, 1931; Kofoid and Swezy, 
1921; Prescott, 1928; Eddy, 1930; Playfair, 1919; Wailes, 1934; 
Thompson, 1947, 1950; Balech, 1944, 1949, 1951; Rampi, 1950; 
Chatton, 1952); locomotion (Peters, 1929). 

The Dinoflagellata are subdivided into three major groups: 

Bivalve shell without furrows Suborder 1 Prorocentrinea 

Naked or with shell showing furrows. .Suborder 2 Peridiniinea (p. 313) 

Naked; without furrows; no transverse flagellum 

Suborder 3 Cystoflagellata (p. 329) 

Suborder 1 Prorocentrinea Poche 

Test bivalve; without any groove; with yellow chromatophores; 
2 flagella anterior, one directed anteriorly, the other vibrates in a 
circle; fresh or salt water. 

Family Prorocentridae Kofoid 

Genus Prorocentrum Ehrenberg. Elongate oval; anterior end 
bluntly pointed, with a spinous projection at pole; chromatophores 
small, yellowish brown; salt water. Species (Schiller, 1918, 1928). 

P. micans E. (Fig. 126, a). 36-52/x long; a cause of "red water." 

P. triangulatum Martin. Triangular with rounded posterior end; 
shell-valves flattened; one valve with a delicate tooth; surface cov- 
ered with minute pores; margin striated; chromatophores yellow- 
brown, irregular, broken up in small masses; 17-22^. Martin (1929) 
found it extremely abundant in brackish water in New Jersey. 

Genus Exuviaella Cienkowski. Subspherical or oval; no anterior 
projection, except 2 flagella; 2 lateral chromatophores, large, brown, 
each with a pyrenoid and a starch body; nucleus posterior; salt 
and fresh water. Several species (Schiller, 1918, 1928). 

E. marina C. (Fig. 126, b, c). 36-50 M long. 

E. apora Schiller. Compressed, oval; striae on margin of valves; 
chromatophores numerous yellow-brown, irregular in form; 30-32/x 
by 21-26/x (Schiller); 17-22 M by 14-1 % (Lebour; Martin); common 
in brackish water, New Jersey. 

E. compressa (Stein). Flattened ellipsoid test; anterior end with a 



depression through which two flagella emerge; two chromatophores 
pale or deep green, each with a pyrenoid; nucleus posterior; no 
stigma; 22-26/x by 15-18/z by 11-12/*; fresh and salt water (Thomp- 
son, 1950). 

Suborder 2 Peridiniinea Poche 

Typical dinoflagellates with one to many transverse annuli and 
a sulcus; 2 flagella, one of which undergoes a typical undulating 
movement, while the other usually directed posteriorly. According 

Fig. 126. a, Prorocentrum micans, X420 (Schiitt); b, c, Exuviaella 
marina, X420 (Schiitt); d, e, Cystodinium steini, X370 (Klebs); f, Gleno- 
dinium cinctum, X590 (Schilling); g, G. pulvisculum, X420 (Schilling); 
h, G. uliginosum, X590 (Schilling); i, G. edax, X490 (Schilling); j, 
G. neglectum, X650 (Schilling). 

to Kofoid and Swezy, this suborder is divided into two tribes. 

Body naked or covered by a thin shell Tribe 1 Gymnodinioidae 

Body covered by a thick shell Tribe 2 Peridinioidae (p. 324) 

Tribe 1 Gymnodinioidae Poche 

Naked or covered by a single piece cellulose membrane with an- 
nulus and sulcus, and 2 flagella; chromatophores abundant, yellow 
or greenish platelets or bands; stigma sometimes present; asexual 
reproduction, binary or multiple division; holophytic, ho lo zoic, or 


sap ro zoic; the majority are deep-sea forms; a few coastal or fresh 
water forms also occur. 

With a cellulose membrane Family 1 Cystodiniidae 

Without shell 

Furrows rudimentary Family 2 Pronoctilucidae 

Annulus and sulcus distinct 

With ocellus Family 3 Pouchetiidae (p. 316) 

Without ocellus 

With tentacles Family 4 Noctilucidae (p. 316) 

Without tentacles 

Free-living Family 5 Gymnodiniidae (p. 318) 

Parasitic Family 6 Blastodiniidae (p. 321) 

Permanently colonial Family 7 Polykrikidae (p. 324) 

Family 1 Cystodiniidae Kofoid and Swezy 

Genus Cystodinium Klebs. In swimming phase, oval, with ex- 
tremely delicate envelope; annulus somewhat acyclic; cyst-mem- 
brane drawn out into 2 horns. Species (Pascher, 1928; Thompson, 

C. steini K. (Fig. 126, d, e). Stigma beneath sulcus; chromato- 
phores brown; swarmer about 45^ long; freshwater ponds. 

Genus Glenodinium Ehrenberg. (Glenodiniopsis, Stasziecella 
Woloszynska). Spherical; ellipsoidal or reniform in end-view; an- 
nulus a circle; several discoidal, yellow to brown chromatophores; 
horseshoe- or rod-shaped stigma in some; often with gelatinous en- 
velope; fresh water. Many species (Thompson, 1950). 

G. cinctum E. (Fig. 126,/). Spherical to ovoid; annulus equatorial; 
stigma horseshoe-shaped; 43 ai by 40/x. Morphology and reproduction 
(Lindemann, 1929). 

G. pulvisculum Stein (Fig. 126, g). No stigma; 38/x by 30ju. 

G. uliginosum Schilling (Fig. 126, h). 36-48m by 3G> 

G. edax S. (Fig. 126, i). 34/x by 33/x. 

G. neglectum S. (Fig. 126, j). 30-32 M by 29 M . 

Family 2 Pronoctilucidae Lebour 

Genus Pronoctiluca Fabre-Domergue. Body with an antero- 
ventral tentacle and sulcus; annulus poorly marked; salt water. 

P. tentaculatum (Kofoid and Swezy) (Fig. 127, a). About 54ju long; 
off California coast. 

Genus Oxyrrhis Dujardin. Subovoidal, asymmetrical posteriorly; 
annulus incomplete; salt water. 

0. marina D. (Fig. 127, 6). 10-37/x long. Division (Dunkerly, 1921; 
Hall, 1925). 



Fig. 127. a, Pronoctiluca tentaculatum, X730 (Kofoid and Swezy); 
b, Oxyrrhis marina, X840 (Senn); c. Pouchetia fusus, X340 (Schiitt); 
d, P. maxima, X330 (Kofoid and Swezy); e, Protopsis ochrea, X340 
(Wright); f, Nematodinium partitum, X560 (Kofoid and Swezy); g, Pro- 
terythropsis crassicaudata, X740 (Kofoid and Swezy); h, Erythropsis 
cornuta, X340 (Kofoid and Swezy); i, j , Noctiluca scintillans (i, side view; 
j, budding process), X140 (Robin). 


Family 3 Pouchetiidae Kofoid and Swezy 

Ocellus consists of lens and melanosome (pigment mass); sulcus 
and annulus somewhat twisted; pusules usually present; cytoplasm 
colored; salt water (pelagic). 

Genus Pouchetia Schutt. Nucleus anterior to ocellus; ocellus with 
red or black pigment mass with a red, brown, yellow, or colorless 
central core; lens hyaline; body surface usually smooth; ho lo zoic; 
en^ystment common; salt water. Many species (Schiller, 1928a). 

P. fusus S. (Fig. 127, c). About 94/t by 41/x; ocellus 27m long. 

P. maxima Kofoid and Swezy (Fig. 127, d). 145/t by 92/*; ocellus 
20/x; off California coast. 

Genus Protopsis Kofoid and Swezy. Annulus and sulcus similar 
to those of Gymnodinium or Gyrodinium; with a simple or compound 
ocellus; no tentacles; body not twisted; salt water. A few species. 

P. ochrea (Wright) (Fig. 127, e). 55/i by 45/z; ocellus 22/i long; 
Nova Scotia. 

Genus Nematodinium Kofoid and Swezy. With nematocysts; 
girdle more than 1 turn; ocellus distributed or concentrated, pos- 
terior; holozoic; salt water. 

N. partitum K. and S. (Fig. 127, /). 91/* long; off California coast. 

Genus Proterythropsis Kofoid and Swezy. Annulus median; ocel- 
lus posterior; a stout rudimentary tentacle; salt water. One species. 

P. crassicaudata K. and S. (Fig. 127, g). 70/t long; off California. 

Genus Erythropsis Hertwig. Epicone flattened, less than 1/4 
hypocone; ocellus very large, composed of one or several hyaline 
lenses attached to or imbedded in a red, brownish or black pigment 
body with a red, brown or yellow core, located at left of sulcus; 
sulcus expands posteriorly into ventro -posterior tentacle; salt water. 
Several species. 

E. cornuta (Schutt) (Fig. 127, h). 104/x long; off California coast 
(Kofoid and Swezy). 

Family 4 Noctilucidae Kent 

Contractile tentacle arises from sulcal area and extends poste- 
riorly; a flagellum; this group has formerly been included in the 
Cystoflagellata; studies by recent investigators, particularly by 
Kofoid, show its affinity with the present suborder ; holozoic ; saltwater. 

Genus Noctiluca Suriray. Spherical, bilaterally symmetrical; peri- 
stome marks the median line of body; cytostome at the bottom of 
peristome; with a conspicuous tentacle and a short flagellum; cyto- 
plasm greatly vacuolated, and cytoplasmic strands connect the cen- 
tral mass with periphery; specific gravity is less than that of sea wa- 



ter, due to the presence of an osmotically active substance with a 
lower specific gravity than sodium chloride, which appears to be 
ammonium chloride (Goethard and Heinsius); certain granules are 
luminescent (Fig. 128); cytoplasm colorless or blue-green; sometimes 
tinged with yellow coloration in center; swarmers formed by bud- 
ding, and each possesses one flagellum, annulus, and tentale; widely 
distributed in salt water; holozoic. One species. 

N. scintillans f Macartney) (N. miliaris S.) (Figs. 127, i,j; 128). 
Usually 500-IOOOm in diameter, with extremes of 200/u and 3 mm. 
Gross (1934) observed that complete fusion of two swarmers (isoga- 
metes) results in cyst formation from which trophozoites develop. 
Acid content of the body fluid is said to be about pH 3. Nuclear di- 

Fig. 128. Noctiluca scintillans, as seen under darkfield microscope 
(Pratje). a, an active individual; b, a so-called "resting stage," with fat 
droplets in the central cytoplasm, prior to either division or swarmer 
formation; c, d, appearance of luminescent individuals (F, fat-droplets; 
K, nucleus; P, peristome; T, tentacle; V, food body; Z, central proto- 


vision (Calkins, 1898); morphology and physiology (Goor, 1918; 
Kofoid, 1920; Pratje, 1921); feeding (Hofker, 1930); luminescence 
(Harvey, 1952). 

Genus Pavillardia Kofoid and Swezy. Annulus and sulcus similar 
to those of Gymnodinium; longitudinal flagellum absent; stout 
finger-like mobile tentacle directed posteriorly; salt water. One 

P. tentaculifera K. and S. 58m by 27/x; pale yellow; off California. 

Family 5 Gymnodiniidae Kofoid 

Naked forms with simple but distinct 1/2-4 turns of annulus; 
with or without chromatophores; fresh or salt water. 

Genus Gymnodinium Stein. Pellicle delicate; subcircular; bi- 
laterally symmetrical; numerous discoid chromatophores vari- 
colored (yellow to deep brown, green, or blue) or sometimes absent; 
stigma present in few; many with mucilaginous envelope; salt, 
brackish, or fresh water. Numerous species (Schiller, 1928a) ; culti- 
vation and development (Lindemann, 1929). 

G. aeruginosum S. (Fig. 129, a). Green chromatophores; 20-32/x by 
13-25/x (Thompson, 1950) ; ponds and lakes. 

G. rotundatum Klebs (Fig. 129, b). 32-35/x by 22-25 M ; fresh water. 

G. palustre Schilling (Fig. 129, c). 45/z by 38^; fresh water. 

G. agile Kofoid and Swezy (Fig. 129, d). About 28m long; along 
sandy beaches. 

Genus Hemidinium Stein. Asymmetrical; oval; annulus about 
half a turn, only on left half. One species. 

H. nasutum S. (Fig. 129, e). Sulcus posterior; chromatophores 
yellow to brown; with a reddish brown oil drop; nucleus posterior; 
transverse fission; 24-28ju by 16-17/x; fresh water. 

Genus Amphidinium Claparede and Lachmann. Form variable; 
epicone small; annulus anterior; sulcus straight on hypo cone or also 
on part of epicone; with or without chromatophores; mainly holo- 
phytic, some holozoic; coastal or fresh water. Numerous species 
Schiller, 1928a). 

A. lacustre Stein (Fig. 129, /). 30/t by 18/x; in fresh and salt (?) 

A. scissum Kofoid and Swezy (Fig. 129, g). 50-60m long; along 
sandy beaches. 

A. fusiforme Martin. Fusiform, twice as long as broad: circular 
in cross-section; epicone rounded conical; annulus anterior; hypo- 
cone 2-2.5 times as long as epicone; sulcus obscure; body filled with 



Fig. 129. a, Gymnodinium aeruginosum, X500 (Schilling); b, G. ro- 
tundatum, X360 (Klebs); c, G. palustre, X360 (Schilling); d, G. agile, 
X740 (Kofoid and Swezy); e, Hemidinium nasutum, X670 (Stein); 
f, Amphidinium lacustre, X440 (Stein); g, A. scissum, X8S0 (Kofoid 
and Swezy); h, Gyrodinium biconicum, X340 (Kofoid and Swezy); 
i, G. hyalinum, X670 (Kofoid and Swezy); j, Cochlodinium atromacu- 
latum, X340 (Kofoid and Swezy); k, Torodinium robustum, X670 
(Kofoid and Swezy); 1, Massartia nieuportensis, X670 (Conrad); m, 
Chilodinium cruciatum, X900 (Conrad); n, o, Trochodinium prismaticum, 
X1270 (Conrad); p, Ceratodinium asymmetricum, X670 (Conrad). 


yellowish green chromatophores except at posterior end ; stigma dull 
orange, below girdle; nucleus ellipsoid, posterior to annulus; pellicle 
delicate; 17-22ju by 8-1 1/z in diameter. Martin (1929) found that it 
was extremely abundant in parts of Delaware Bay and gave rise to 
red coloration of the water ("Red water"). 

Genus Gyrodinium Kofoid and Swezy. Annulus descending left 
spiral; sulcus extending from end to end; nucleus central; pusules; 
surface smooth or striated; chromatophores rarely present; cyto- 
plasm colored; holozoic; salt or fresh water. Many species (Schiller, 

Q. biconicum K. and S. (Fig. 129, h). 68 n long; salt water; off Cali- 

G. hyalinum (Schilling) (Fig. 129, i). About 24^ long; fresh water. 

Genus Cochlodinium Schlitt. Twisted at least 1.5 turns; annulus 
descending left spiral; pusules; cytoplasm colorless to highly colored; 
chromatophores rarely present; holozoic; surface smooth or striated; 
salt water. Numerous species (Schiller, 1928a). 

C. atromaculatum Kofoid and Swezy (Fig. 129, j). 183-185/x by 
72ju; longitudinal flagellum 45/x long; off California. 

Genus Torodinium Kofoid and Swezy. Elongate; epicone several 
times longer than hypocone; annulus and hypocone form augur- 
shaped cone; sulcus long; nucleus greatly elongate; salt water. 2 
species (Schiller, 1928). 

T. robustum K. and S. (Fig. 129, k). 67-75/z long; off California. 

Genus Massartia Conrad. Cylindrical; epicone larger (9-10 times 
longer and 3 times wider) than hypocone; no sulcus; with or without 
yellowish discoid chromatophore (Thompson, 1950). 

M . nieuportensis C. (Fig. 129, 1). 28-37/x long; brackish water. 

Genus Chilodinium Conrad. Ellipsoid; posterior end broadly 
rounded, anterior end narrowed and drawn out into a digitform 
process closely adhering to body; sulcus, apex to 1/5 from posterior 
end; annulus oblique, in anterior 1/3 (Conrad, 1926). 

C. cruciatum C. (Fig. 129, m). 40-50ju by 30-40/z; with trichocysts; 
brackish water. 

Genus Trochodinium Conrad. Somewhat similar to Amphidi- 
nium; epicone small, button-like; hypocone with 4 longitudinal 
rounded ridges; stigma; without chromatophores. 

T. prismaticum C. (Fig. 129, n, o). 18-22/x by 9-12;u; epicone 
5-7 jit in diameter; brackish water (Conrad, 1926). 

Genus Ceratodinium Conrad. Cuneiform; asymmetrical, color- 
less, more or less flattened; annulus complete, oblique; sulcus on half 
of epicone and full length of hypocone; stigma. 


C. asymmetricum C. (Fig. 129, p). 68-80^ by about 10/x; brackish 
water (Conrad, 1926). 

Family 6 Elastodiniidae Kofoid and Swezy 

All parasitic in or on plants and animals; in colony forming genera, 
there occur trophocyte (Chatton) by which organism is attached to 
host and more or less numerous gonocytes (Chatton). Taxonomy 
(Chatton, 1920; Reichenow, 1930). 

Genus BJastodinium Chatton. In the gut of copepods; spindle- 
shaped, arched, ends attenuated; envelope (not cellulose) often with 
2 spiral rows of bristles; young forms binucleate; when present, 
chromatophores in yellowish brown network; swarmers similar to 
those of Gymnodinium; in salt water. Many species. 

B. spinulosum C. (Fig. 130, a). About 235/* by 33-39/z; swarmers 
5-10ju; in Palacalanus parvus, Clausocalanus arcuicornis and C. 

Genus Oodinium Chatton. Spherical or pyriform; with a short 
stalk; nucleus large; often with yellowish pigment; on Salpa, Anne- 
lida, Siphonophora, marine fishes, etc. 

0. poucheti (Lemmermann) (Fig. 130, b, c). Fully grown indivi- 
duals up to 170/x long; bright yellow ochre; mature forms become 
detached and free, dividing into numerous gymnodinium-like 
swarmers; on the tunicate. Oikopleura dioica. 

O. ocellatum Brown (Fig. 131, a, b). Attached to the gill filaments of 
marine fish by means of cytoplasmic processes; oval in form; 12m by 
10m to 104m by 80m, average 60m by 50m; nucleus spherical; many 
chromatophores and starch grains; a stigma. When grown, the or- 
ganism drops off the gill and becomes enlarged to as much as 150m 
in diameter. Soon the cytoplasmic processes and the broad flagel- 
lum are retracted and the aperture of shell closes by secretion of 
cellulose substance. The body divides up to 128 cells, which become 
flagellated and each divides once more. These flagellates, 12/x by 8m, 
reach the gills of fish and become attached (Brown, 1931; Nigrelli, 

O. limneticum Jacobs (Fig. 131, c, d). Pyriform; 12ju by 7.5m to 
20ju by 13/x; light green chromatophores variable in size and shape; 
no stigma; without flagella; filopodia straight or branched; the or- 
ganism grows into about 60m long in three days at 25°C; observed 
maximum, 96m by 80m; starch becomes abundant; fission takes place 
in cyst; flagellate forms measure about 15m long; ectoparasitic on the 
integument of freshwater fishes in aquaria (Jacobs, 1946). 



Genus Apodinium Chatton. Young individuals elongate, spherical 
or pyriform; binucleate; adult colorless; formation of numerous 
swarmers in adult stage is peculiar in that lower of the 2 individuals 
formed at each division secretes a new envelope, and delays its 

Fig. 130. a, Blastodinium spinxdosum, X240 (Chatton); b, c, Oodi- 
nium poucheti (c, a swarmer) (Chatton); d, e, Apodinium mycetoides 
(d, swarmer-formation, X450; e, a younger stage, X640) (Chatton); 
f, Chytriodiniuxn parasiticum in a copepod egg (Dogiel); g, Trypanodinium 
ovicola, X1070 (Chatton); h, Duboscqella tintinnicola (Duboscq and 
Collin); i, j, Haplozoon clymenellae (i, mature colony, X300; j, a swarmer, 
X1340) (Shumway); k, Syndinium turbo, X1340 (Chatton); 1, Paradi- 
nium poucheti, X800 (Chatton); m, Ellobiopsis chattoni on Calanus fin- 
marchicus (Caullery); n, Paraellobiopsis coutieri (Collin). 



further division until the upper one has divided for the second time, 
leaving several open cups; on tunicates. 

A. mycetoides C. (Fig. 130, d, e). On gill-slits of Fritillaria pel- 

Genus Chytriodinium Chatton. In eggs of planktonic copepods; 
young individuals grow at the expense of host egg and when fully 
formed, body divides into many parts, each producing 4 swarmers. 
Several species. 

C. parasiticum (Dogiel) (Fig. 130, /). In copepod eggs; Naples. 

Genus Trypanodinium Chatton. In copepod eggs; swarmer-stage 
only known. 

Fig. 131. a, Oodinium ocellatum, recently detached from host gill; 
b, a free living flagellate form, X760 (Nigrelli); c, d, 0. limneticum, X800 

T. ovicola C. (Fig. 130, g). Swarmers biflagellate; about 15ju long. 

Genus Duboscqella Chatton. Rounded cell with a large nucleus; 
parasitic in Tintinnidae. One species. 

D. tiniinnicola (Lohmann) (Fig. 130, h). Intracellular stage oval, 
about 100^ in diameter with a large nucleus; swarmers biflagellate. 

Genus Haplozoon Dogiel. In gut of polychaetes; mature forms 
composed of variable number of cells arranged in line or in pyramid; 
salt water. Many species. 

H. clymenellae (Calkins) (Microtaeniella clymenellae C.) (Fig. 130, 
i,j). In the intestine of Clymenella torquata; colonial forms consist of 
250 or more cells; Woods Hole (Shumway, 1924). 

Genus Syndinium Chatton. In gut and body cavity of marine 
copepods; multinucleate round cysts in gut considered as young 


forms; multinucleate body in host body cavity with numerous 
needle-like inclusions. 

S. turbo C. (Fig. 130, k). In Paracalanus parvus, Corycaeus ven- 
ustus, Calanus finmarchicus; swarmers about 15/x long. 

Genus Paradinium Chatton. In body-cavity of copepods; mul- 
tinucleate body without inclusions; swarmers formed outside the 
host body. 

P. poucheti C. (Fig. 130, 1). In the copepod, Acartia clausi; swarm- 
ers about 25,u long, amoeboid. 

Genus Ellobiopsis Caullery. Pyriform; with stalk; often a septum 
near stalked end; attached to anterior appendages of marine cope- 

E. chattoni C. (Fig. 130, m). Up to 700/c long; on antennae and 
oral appendages of Calanus finmarchicus, Pseudocalanus elongatus 
and Acartia clausi. Development (Steuer, 1928). 

Genus Paraellobiopsis Collin. Young forms stalkless; spherical; 
mature individuals in chain-form; on Malacostraca. 

P. coutieri C. (Fig. 130, n). On appendages of Nebalia bipes. 

Family 7 Polykrikidae Kofoid and Swezey 

Two, 4, 8, or 16 individuals permanently joined; individuals 
similar to Gymnodinium; sulcus however extending entire body 
length; with nematocysts (Fig. 132, 6); greenish to pink; nuclei 
about 1/2 the number of individuals; holozoic; salt water. Nemato- 
cysts (Hovasse, 1951). 

Genus Polykrikos Btitschli. With the above-mentioned characters; 
salt or brackish water. Species (Schiller, 1928). 

P. kofoidi (Chatton) (Fig. 132, a, 6). Greenish grey to rose; com- 
posed of 2, 4, 8, or 16 individuals; with nematocysts; each nemato- 
cyst possesses presumably a hollow thread, and discharges under 
suitable stimulation its content; a binucleate colony composed of 4 
individuals about 110m long; off California. 

P. barnegatensis Martin. Ovate, nearly circular in cross-section, 
slightly concave ventrally; composed of 2 individuals; constriction 
slight; beaded nucleus in center; annuli descending left spiral, dis- 
placed twice their width; sulcus ends near anterior end; cytoplasm 
colorless, with numerous oval, yellow-brown chromatophores; nem- 
atocysts absent; 46m by 31.5/*; in brackish water of Barnegat Bay. 

Tribe 2 Peridinioidae Poche 

The shell composed of epitheca, annulus and hypotheca, which 
may be divided into numerous plates; body form variable. 



With annulus and sulcus 
Shell composed of plates; but no suture. . . Family 1 Peridiniidae (p. 326) 
Breast plate divided by sagittal suture. Family 2 Dinophysidae (p. 328) 

Without annulus or sulcus Family 3 Phytodiniidae (p. 329) 

Fig. 132. a, b, Polykrikos kofoidi (a, colony of four individuals, X340; 
b, a nematocyst, X1040) (Kofoid and Swezy); c, Peridinium tabulatum, 
X460 (Schilling); d, P. divergens, X340 (Calkins); e, Ceratium hirundi- 
nella, X540 (Stein); f. C. longipes, X100 (Wailes); g, C. tripos, X140 
(Wailes); h, C. fusxis, X100 (Wailes); i, Heterodinium scrippsi, X570 
(Kofoid and Adamson). 


Family 1 Peridiniidae Kent 

Shell composed of numerous plates; annulus usually at equator, 
covered by a plate known as cingulum; variously sculptured and 
finely perforated plates vary in shape and number among different 
species; in many species certain plates drawn out into various proc- 
esses, varying greatly in different seasons and localities even among 
one and the same species; these processes seem to retard descending 
movement of organisms from upper to lower level in water when 
flagellar activity ceases; chromatophores numerous small platelets, 
yellow or green; some deep-sea forms without chromatophores; chain 
formation in some forms; mostly surface and pelagic inhabitants in 
fresh or salt water. 

Genus Peridinium Ehrenberg. Subspherical to ovoid; reniform in 
cross-section; annulus slightly spiral with projecting rims; hypotheca 
often with short horns and epitheca drawn out; colorless, green, or 
brown; stigma usually present; cysts spherical; salt or fresh water. 
Numerous species. Species and variation (Bohm, 1933; Diwald, 
1939); Chromatophore and pyrenoid (Geitler, 1926). 

P. tabulation Claparede and Lachmann (Fig. 132, c). 48/t by 44/i; 
fresh water. 

P. diver gens (E.) (Fig. 132, d). About 45/i in diameter; yellowish, 
salt water. 

Genus Ceratium Schrank. Body flattened; with one anterior and 
1-4 posterior horn-like processes; often large; chromatophores yel- 
low, brown, or greenish; color variation conspicuous; fission is said 
to take place at night and in the early morning; fresh or salt water. 
Numerous species; specific identification is difficult due to a great 
variation (p. 223). Biology and morphology (Entz, 1927); encyst- 
ment (Entz, 1925). 

C. hirundinella (Muller) (Figs. 94; 132, e). 1 apical and 2-3 antap- 
ical horns; seasonal and geographical variations (p. 223); chain- 
formation frequent; 95-700/x long; fresh and salt water. Numerous 
varieties. Reproduction (Entz, 1921, 1931; Hall, 1925a; Borgert, 
1935); holozoic nutrition (Hofeneder, 1930). 

C. longipes (Bailey) (Fig. 132, /). About 210/i by 51-57 M ; salt 

C. tripos (Muller) (Fig. 132,0). About 225/i by 75/x; salt water. Wailes 
(1928) observed var. atlantica in British Columbia; Martin (1929) 
in Barnegat Inlet, New Jersey. Nuclear division (Schneider, 1924). 

C.fusus (Ehrenberg) (Fig. 132, h). 300-600/x by 15-30/*; salt water; 
widely distributed; British Columbia (Wailes), New Jersey (Martin), 


Genus Heterodinium Kofoid. Flattened or spheroidal; 2 large 
antapical horns; annulus submedian; with post-cingular ridge; sulcus 
short, narrow; shell hyaline, reticulate, porulate; salt water. Numer- 
ous species. 

H. scrippsi K. (Fig. 132, i). 130-155/x long; Pacific and Atlantic 

Genus Dolichodinium Kofoid and Adamson. Subcorneal, elongate; 
without apical or antapical horns; sulcus only 1/2 the length of hy- 
potheca; plate porulate; salt water. 

D. lineatum (Kofoid and Michener) (Fig. 133, a). 58/z long; eastern 
tropical Pacific. 

Genus Goniodoma Stein. Polyhedral with a deep annulus; epi- 
theca and hypotheca slightly unequal in size, composed of regularly 
arranged armored plates; chromatophores small brown platelets; 
fresh or salt water. 

G. acuminata (Ehrenberg) (Fig. 133, b). About 50> long; salt water. 

Genus Gonyaulax Diesing. Spherical, polyhedral, fusiform, 
elongated with stout apical and antapical prolongations, or dorso- 
ventrally flattened; apex never sharply attenuated; annulus equa- 
torial; sulcus from apex to antapex, broadened posteriorly; plates 
1-6 apical, 0-3 anterior intercalaries, 6 precingulars, 6 annular 
plates, 6 postincingulars, 1 posterior intercalary and 1 antapical; 
porulate; chromatophores yellow to dark brown, often dense; with- 
out stigma; fresh, brackish or salt water. Numerous species (Kofoid, 
1911; Whedon and Kofoid, 1936). 

G. polyedra Stein (Fig. 133, c). Angular, polyhedral; ridges along 
sutures, annulus displaced 1-2 annulus widths, regularly pitted; salt 
water. "Very abundant in the San Diego region in the summer 
plankton, July-September, when it causes local outbreaks of 'red 
water,' which extend along the coast of southern and lower Cali- 
fornia" (Kofoid, 1911; Allen, 1946). The organisms occurred also in 
abundance (85 per cent of plankton) in pools of sea water off the 
beach of Areia Branca, Portugal, and caused "red water" during the 
day and an extreme luminescence when agitated at night (Santos- 
Pinto, 1949). 

G. apiculata (Penard) (Fig. 133, d). Ovate, chromatophores yel- 
lowish brown; 30-60/x long; fresh water. 

Genus Spiraulax Kofoid. Biconical; apices pointed; sulcus not 
reaching apex; no ventral pore; surface heavily pitted; salt 

S. jolliffei (Murray and Whitting) (Fig. 133, e). 132^ by 92^; 
California (Kofoid, 1911a). 



Genus Woloszynskia Thompson (1950). An apparently intermedi- 
ate form between Gymnodinioidae and Peridinioidae. 

Family 2 Dinophysidae Kofoid 

Genus Dinophysis Ehrenberg. Highly compressed; annulus wid- 
ened, funnel-like, surrounding small epitheca; chromatophores yel- 
low; salt water. Several species (Schiller, 1928). Morphology and 
taxonomy (Tai and Skogsberg, 1934). 

Fig. 133. a, Dolichodinium lineatum, X670 (Kofoid and Adamson), 
b, Goniodoma acuminata, X340 (Stein); c, Gonyaulax polyedra, X670 
(Kofoid); d, G. apiculata, X670 (Lindemann) ; e, Spiraulax jolliffei, 
right side of theca, X340 (Kofoid); f, Dinophysis acuta, X580 (Schutt); 
g, h, Oxyphysis oxytoxoides, X780 (Kofoid); i, Phytodinium simplex, 
X340 (Klebs); j, k, Dissodinium lunula: j, primary cyst (Dogiel); k, 
secondary cyst with 4 swarmers (Wailes), X220. 


D. acuta E. (Fig. 133,/). Oval; attenuated posteriorly ;54-94/z long; 
widely distributed; British Columbia (Wailes). 

Genus Oxyphysis Kofoid. Epitheca developed; sulcus short; sulcal 
lists feebly developed; sagittal suture conspicuous; annulus im- 
pressed; salt water (Kofoid, 1926). 

0. oxytoxoides K. (Fig. 133, g, h). 63-68 M by 15/*; off Alaska. 

Family 3 Phytodiniidae Klebs 

Genus Phytodinium Klebs. Spherical or ellipsoidal; without fur- 
rows; chromatophores discoidal, yellowish brown. 

P. simplex K. (Fig. 133, i). Spherical or oval; 42-50/x by 30-45m 
fresh water. 

Genus Dissodinium Klebs (Pyrocystis Paulsen). Primary cyst, 
spherical, uninucleate; contents divide into 8-16 crescentic second- 
ary cysts which become set free; in them are formed 2, 4, 6, or 8 
Gymnodinium-like swarmers; salt water. 

Fig. 134. a, Leptodiscus medusoides, X50 (Hertwig); b, Craspedotella 
pileolus, X110 (Kofoid). 

D. lunula (Schutt) (Fig. 133, j, k). Primary cysts 80-155/* in 
diameter; secondary cysts 104-130/z long; swarmers 22/x long; widely 
distributed; British Columbia (Wailes). 

Suborder 3 Cystoflagellata Haeckel 

Since Noctiluca which had for many years been placed in this 
suborder, has been removed, according to Kofoid, to the second sub- 
order, the Cystoflagellata becomes a highly ill-defined group and 
includes two peculiar marine forms: Leptodiscus medusoides Hertwig 
(Fig. 134, a), and Craspedotella pileolus Kofoid (Fig. 134, b), both 
of which are medusoid in general body form. 


Allen, W. E.: (1946) Significance of "red water" in the sea. Turtox 
news, 24:49. 

Balech, E.: (1949) Etude de quelques especes de Peridinium, sou- 
vent confondues. Hydrobiologia, 1:390. 

(1951) Deuxieme contribution a la connaissance des Peridi- 
nium. Ibid., 3:305. 


Bohm, A.: (1933) Beobachtungen an adriatischen Peridinium-Arten. 

Arch. Protist, 80:303. 
Borgert, A.: (1935) Fortpflanzungsvorgange und Heteromorphis- 

mus bei marinen Ceratien, etc. Ibid., 86:318. 
Brown, E. M.: (1931) Note on a new species of dinoflagellate from 

the gills and epidermis of marine fishes. Proc. Zool. Soc. London, 

Calkins, G. N.: (1898) Mitosis in Noctiluca milliaris. 58 pp. 
Chatton, E.: (1920) Les Peridiniens parasites: Morphologie, re- 
production, ethologie. Arch. zool. exper. gen., 59:1. 
(1952) Classe des Dinoflagelles ou Peridiniens. In: Grasse 

(1952), p. 310. 
Conrad, W.: (1926) Recherches sur les flagellates de nos eaux 

saumatres. I. Arch. Protist., 55:63. 
Diwald, K.: (1939) Ein Beitrag zur Variabilitat und Systematik der 

Gattung Peridinium. Ibid., 93:121. 
Dunkerly, J. S.: (1921) Nuclear division in the dinoflagellate, 

Oxyrrhis marina. Proc. Roy. Phys. Soc, Edinburgh, 20:217. 
Eddy, S.: (1930) The freshwater armored or thecate dinoflagellates. 

Tr. Am. Micr. Soc, 49:1. 
Entz, G.: (1921) Ueber die mitotische Teilung von Ceratium hi- 

rundinella. Arch. Protist., 43:415. 
— (1925) Ueber Cysten und Encystierung der Siisswasser- 

Ceratien. Ibid., 51:131. 

— (1927) Beitrage zur Kenntnis der Peridineen. Ibid., 58:344. 
(1931) Analyse des Wachstums und Teilung einer Population 

sowie eines Individuums des Protisten Ceratium, etc. Ibid., 74: 

Fritsch, F. E.: (1935) The structure and reproduction of the algae. 
Galtsoff, P. S.: (1948) Red tide: etc. Spec. Sc Rep., U. S. Fish 

Wildl. Service, no. 46. 

(1949) The mystery of the red tide. Sc. Monthly, 68:109. 

Geitler, L.: (1926) Ueber Chromatophoren und Pyrenoide bei 

Peridineen. Arch. Protist., 53:343. 
Goor, A. C. J. Van: (1918) Die Cytologie von Noctiluca miliaris. 

Ibid., 39:147. 
Graham, H. W.: (1943) Gymnodinium catenatum, etc. Tr. Am. 

Micr. Soc, 62:259. 
Gross, F.: (1934) Zur Biologie und Entwicklungsgeschichte von 

Noctiluca miliaris. Arch. Protist., 83:178. 
Hall, R. P.: (1925) Binary fission in Oxyrrhis marina. Univ. Cali- 
fornia Publ. Zool, 26:281. 

(1925a) Mitosis in Ceratium hirundinella, etc. Ibid, 28:29. 

Harvey, E. N.: (1952) Bioluminescence. New York. 

Hofeneder, H. : (1930) Ueber die animalische Ernahrung von 

Ceratium, etc. Arch. Protist, 71:1. 
Hofker, J.: (1930) Ueber Noctiluca scintillans. Ibid, 71:57. 
Hovasse, R.: (1951) Contribution a l'etude de la cnidogenese chez 

les Peridiniens. I. Arch. zool. exper. gen, 87:299. 
Jacobs, D. L.: (1946) A new parasitic dinoflagellate from freshwater 

fish. Tr. Am. Micr. Soc, 65:1. 


Ketchum, B. H. and Keen, Jean: (1948) Unusual phosphorus con- 
centrations in the Florida "red tide" sea water. J. Mar. Res., 7: 

Kofoid, C. A.: (1907) The plate of Ceratium, etc. Zool. Anz., 32: 

— (1909) On Peridinium steinii, etc. Arch. Protist., 14:25. 
(1911) Dinoflagellata of the San Diego Region. IV. Uni. Cal. 

Publ. Zool., 8:187. 

- (1911a) V. Ibid., 8:295. 
(1920) A new morphological interpretation of Noctiluca, etc. 

Ibid., 19:317. 
(1926) On Oxyphysis oxytoxoides, etc. Ibid., 28:203. 

— (1931) Report of the biological survey of Mutsu Bay. XVIII. 
Sc. Rep. Tohoku Imp. Uni., Biol., 6:1. 

— and Adamson, A. M.: (1933) The Dinoflagellata: the family 
Heterodiniidae, etc. Mem. Mus. Comp. Zool. Harvard, 54:1. 

— and Swezy, Olive: (1921) The free-living unarmored Dino- 
flagellata. Mem. Univ. California, 5:1. 

Lebour, Marie V. : (1925) The dinoflagellates of northern seas. 

Lindemann, E.: (1929) Experimentelle Studien uber die Fortpflanz- 

ungserscheinungen der Siisswasserperidineen auf Grund von 

Reinkulturen. Arch. Protist., 68:1. 
Martin, G. W.: (1929) Dinoflagellates from marine and brackish 

waters of New Jersey. Univ. Iowa Stud. Nat. Hist., 12, no. 9. 
Nigrelli, R. F.: (1936) The morphology, cytology and life-history 

of Oodinium ocellatum Brown, etc. Zoologica, 21 : 129. 
Pascher, A.: (1928) Von einer neue Dinococcale, etc. Arch. Protist., 

Peters, N.: (1929) Ueber Orts- und Geisselbewegung bei marinen 

Dinoflagellaten. Ibid., 67:291. 
Playfair, G. I.: (1919) Peridineae of New South Wales. Proc. Linn. 

Soc. N.S.Wales, 44:793. 
Pratje, A.: (1921) Noctiluca miliaris Suriray. Beitrage zur Morpho- 

logie, Physiologie und Cytologic I. Arch. Protist., 42:1. 
Prescott, G. W. : (1928) The motile algae of Iowa. Univ. Iowa Stud. 

Nat. Hist., 12:5. 
Rampi, L. : (1950) Peridiniens rares ou nouveaux pour la Pacifique 

Sud-Equatorial. Bull. lTnst. Oceanogr., no. 974. 
Reichenow, E.: (1930) Parasitische Peridinea. In: Grimpe's Die 

Tierwelt der Nord- und Ost-See. Pt. 19, II, d3. 
Santos-Pinto, J. d.: (1949) Um caso de "red water" motivado por 

abundancia anormal de Gonyaulax poliedra. Bol. Soc. Port. Ci. 

Nat., 17:94. 
Schiller, J.: (1918) Ueber neue Prorocentrum- und Exuviella- 

Arten, etc. Arch. Protist., 38:250. 
■ (1928) Die planktischen Vegetationen des adriatischen 

Meers. I. Ibid., 61:45. 

(1928a) II. Ibid., 62:119. 

Schilling, A.: (1913) Dinoflagellatae (Peridineae). Die Slisswasser- 

flora Deutscblands. Pt. 3. 


Schneider, H.: (1924) Kern und Kernteilung bei Ceratium tripos. 

Arch. Protist., 48:302. 
Shumway, W.: (1924) The genus Haplozoon, etc. Jour. Parasit., 11 : 

Steuer, A.: (1928) Ueber Ellobiopsis chattoni Caullery, etc. Arch. 

Protist., 60:501. 
Tai, L.-S. and Skogsberg, T.: (1934) Studies on the Dinophysoidae, 

etc. Ibid., 82:380. 
Thompson, R. H.: (1947) Freshwater dinoflagellates of Maryland. 

Chesapeake Biol. Lab. Publ., no. 67. 

— (1949) Immobile Dinophyceae. I. Am. J. Bot., 36:301. 

— (1950) A new genus and new records of freshwater Pyrro- 
phyta, etc. Lloydia, 13:277. 
Wailes, G. H.: (1928) Dinoflagellates and Protozoa from British 
Columbia. Vancouver Mus. Notes, 3. 

— (1934) Freshwater dinoflagellates of North America. Ibid., 7, 
Suppl., 11. 

Whedon, W. F. and Kofoid, C. A.: (1936) Dinoflagellates of the 
San Francisco region. I. Univ. California Publ. Zool., 41:25. 

Chapter 13 
Subclass 2 Zoomastigina Doflein 

THE Zoomastigina lack chromatophores and their body organ- 
izations vary greatly from a simple to a very complex type. The 
majority possess a single nucleus which is, as a rule, vesicular in 
structure. Characteristic organellae such as parabasal body, axo- 
style, etc., are present in numerous forms and myonemes are found 
in some species. Nutrition is holozoic or saprozoic (parasitic). Asex- 
ual reproduction is by longitudinal fission; sexual reproduction is un- 
known. Encystment occurs commonly. The Zoomastigina are free- 
living or parasitic in various animals. 

With pseudopodia besides flagella Order 1 Rhizomastigina 

With flagella only 

With 1-2 flagella Order 2 Protomonadina (p. 339) 

With 3-8 flagella Order 3 Polymastigina (p. 369) 

With more than 8 flagella Order 4 Hypermastigina (p. 404) 

Order 1 Rhizomastigina Butschli 

A number of borderline forms between the Sarcodina and the 
Mastigophora are placed here. Flagella vary in number from one to 
several and pseudopods also vary greatly in number and in appear- 

With many flagella Family 1 Multiciliidae 

With 1-3 rarely 4 flagella Family 2 Mastigamoebidae 

Family 1 Multiciliidae Poche 

Genus Multicilia Cienkowski. Generally spheroidal, but amoeboid; 
with 40-50 flagella, long and evenly distributed; one or more nuclei; 
holozoic; food obtained by means of pseudopodia; multiplication by 
fission; fresh or salt water. 

M. marina C. (Fig. 135, a). 20-30ju in diameter; uninucleate; salt 

M. lacustris Lauterborn (Fig. 135, b). Multinucleate; 30-40/x in 
diameter; fresh water. 

Family 2 Mastigamoebidae 

With 1-3 or rarely 4 flagella and axo podia or lobo podia; uninucle- 
ate; flagellum arises from a basal granule which is connected 
with the nucleus by a rhizoplast; binary fission in both trophic and 
encysted stages; sexual reproduction has been reported in one spe- 
cies; holozoic or saprozoic; the majority are free-living, though a few 




Genus Mastigamoeba Schulze (Mastigina Frenzel). Monomasti- 
gote, uninucleate, with finger-like pseudopodia; flagellum long and 
connected with nucleus; fresh water, soil or endocommensal. Species 
(Klug, 1936). 

M. aspera S. (Fig. 135, c). Subspherical or oval; during locomotion 
elongate and narrowed anteriorly, while posterior end rounded or 

Fig. 135. a, Multicilia marina, X400 (Cienkowski) ; b, M. lacustris, 
X400 (Lauterborn) ; c, Mastigamoeba aspera, X200 (Schulze); d, M, 
longifilum, X340 (Stokes); e, M. setosa, X370 (Goldschmidt); f, Masti- 
gellavitrea, X 370 (Goldschmidt). 

lobed; numerous pseudopods slender, straight; nucleus near flagel- 
late end; 2 contractile vacuoles; 150-200> by about 50>; in ooze of 

M. longifilum Stokes (Fig. 135, d). Elongate, transparent; flagel- 
lum twice body length; pseudopods few, short; contractile vacuole 
anterior; body 28/i long when extended, contracted about 10>; stag- 
nant water. 


M. setosa (Goldschmidt) (Fig. 135, e). Up to 140m long. 

M. hylae (Frenzel) (Fig. 136, a). In the hind-gut of the tadpoles of 
frogs and toads: 80-135^ by 21-31 m; flagellum about 10m long 
(Becker, 1925). Development (Ivanic, 1936). 

Genus Mastigella Frenzel. Flagellum apparently not connected 
with nucleus; pseudopods numerous, digitate; body form changes 
actively and continuously; contractile vacuole. 

M. vitrea Goldschmidt (Fig. 135,/). 150/x long; sexual reproduction 

Genus Actinomonas Kent. Generally spheroidal, with a single 
flagellum and radiating pseudopods; ordinarily attached to foreign 
object with a cytoplasmic process, but swims freely by withdrawing 
it; nucleus central; several contractile vacuoles; ho lo zoic. 

A. mirabilis K. (Fig. 136, 6). Numerous simple filopodia; about 
10/x in diameter; flagellum 20ju long; fresh water. 

Genus Dimorpha Gruber. Ovoid or subspherical; with 2 flagella 
and radiating axopodia, all arising from an eccentric centriole; nu- 
cleus eccentric ; pseudopods sometimes withdrawn ; fresh water. Spe- 
cies (Pascher, 1925). 

D. mutans G. (Fig. 136, c). 15-20;u in diameter; flagella about 20- 
30/x long. 

Genus Tetradimorpha Hsiung. Spherical with radiating axopodia; 
four flagella originate in a slightly depressed area; nucleus central. 
When disturbed, all axopodia turn away from the flagellated pole 
and are withdrawn into body, and the organism undergoes swimming 
movement; freshwater ponds. 

T. radiata H. (Fig. 136, d, e). Body 27-38m in diameter; axopodia 
27-65m long; flagella 38-57/z long (Hsiung, 1927). 

Genus Pteridomonas Penard. Small, heart-shaped; usually at- 
tached with a long cytoplasmic process; from opposite pole there 
arises a single flagellum, around which occurs a ring of extremely fine 
filopods; nucleus central; a contractile vacuole; ho lo zoic; fresh water. 

P. pulex P. (Fig. 136,/). 6-12ju broad. 

Genus Histomonas Tyzzer. Actively amoeboid; mostly rounded, 
sometimes elongate; a single nucleus; an extremely fine flagellum 
arises from a blepharoplast, located close to nucleus; axostyle (?) 
sometimes present; in domestic fowls. One species. 

H. meleagridis (Smith) {Amoeba meleagridis S.) (Fig. 137). Ac- 
tively amoeboid organism; usually rounded; 8-21/x (average 10-14/x) 
in the largest diameter; nucleus circular or pyriform with usually a 
large endosome; a fine flagellum; food "vacuoles contain bacteria, 
starch grains and erythrocytes; binary fission; during division flagel- 



lum is discarded; cysts unobserved; in young turkeys, chicks, grouse, 
and quail. Bayon and Bishop (1937) successfully cultured the organ- 
ism from hen's liver. Morphology of the cultured forms (Bishop, 

This organism is the cause of enterohepatitis known as "black- 
head," an infectious disease, in young turkeys and also in other 
fowls, in which it is often fatal. Smith (1895) discovered the organ- 
ism and considered it an amoeba (1910). It invades and destroys the 
mucosa of the intestine and caeca as well as the liver tissues. Tropho- 

Fig. 136. a, Mastigamoeba hylae, X690 (Becker); b, Actinomonas 
mirabilis, XI 140 (Griessmann) ; c, Dimorpha mutans, X940 (Blochmann); 
d, e, Tetradimorpha radiata CHsiung) (d, a typical specimen, X430; e, 
swimming individual, X300); f, Pteridomonas pulex, X540 (Penard); g, 
Rhizomastix gracilis, X1340 (Mackinnon). 



zoites voided in faeces by infected birds may become the source of 
new infection when taken in by young birds with drink or food. 
Tyzzer (1920) found the organism to possess a flagellate stage and 
established the genus Histomonas for it. Tyzzer and Fabyan (1922) 
and Tyzzer (1934) demonstrated that the organism is transmissible 
from bird to bird in the eggs of the nematode Heterakis gallinae, 
which method appears to be a convenient and reliable one for pro- 
ducing Histomonas infection in turkeys (McKay and Morehouse, 

Fig. 137. Histomonas meleagridis. a-d, from host animals (Wenrich); 
e-h, from cultures (Bishop), a, b, organisms in caecum of chicken (in a 
Tyzzer slide); c, an individual from pheasant showing "ingestion tube" 
with a bacterial rod; d, a large individual from the same source, all 
X1765; e, an amoeboid form; f, a rounded form with axostyle (?); g, h, 
stages in nuclear division, X2200. 

1948). Desowitz (1950) noticed in a Heterakis two enlarged gut cells 
filled with amoebulae which he suggested might be a stage of this 
protozoan. Niimi (1937) reported that the organism enters through 
the mouth of the nematode and invades its eggs. Dobell (1940) points 
out the similarity between this flagellate and Dientamoeba fragilis 
(p. 462). Wenrich (1943) made a comparative study of forms found in 


the caecal smears of wild ring-neck pheasants and of chicks. The 
organisms measured 5-30^ in diameter and possessed 1-4 flagella, 
though often there were no flagella. 

Genus Rhizomastix Alexeieff. Body amoeboid; nucleus central: 
blepharoplast located between nucleus and posterior end; a long 
fiber runs from it to anterior end and continues into the flagellum; 
without contractile vacuole; division in spherical cyst. 

R. gracilis A. (Fig. 136, g). 8-14ju long; flagellum 20/x long; in 
intestine of axolotles and tipulid larvae. 

Bayon, H. P. and Bishop, Ann: (1937) Cultivation of Histomonas 

meleagridis from the liver lesions of a hen. Nature, 139:370. 
Becker, E. R. : (1925) The morphology of Mastigina hylae (Frenzel) 

from the intestine of the tadpole. J. Parasit., 11:213. 
Bishop, Ann: (1938) Histomonas meleagridis, etc. Parasit., 30:181. 
Desowitz, R. S.: (1950) Protozoan hyperparasitism of Heterakis 

gallinae. Nature, 165:1023. 
Dobell, C: (1940) Research on the intestinal Protozoa of monkeys 

and man. X. Parasit., 32:417. 
Hsiung, T.-S.: (1927) Tetradimorpha radiata, etc. Tr. Am. Micr. 

Soc, 46:208. 
Klug, G.: (1936) Neue oder wenig bekannte Arten der Gattungen 

Mastigamoeba, etc. Arch. Protist., 87:97. 
Lemmermann, E. : (1914) Pantostomatinae. Slisswasserflora Deutsch- 

lands. Pt. 1. 
McKay, F. and Morehouse, N. F.: (1948) Studies on experimental 

blackhead infection in turkeys. J. Parasit., 34:137. 
Niimi, D.: (1937) Studies on blackhead. II. J. Japan. Soc. Vet. Sc, 

Pascher, A. : (1925) Neue oder wenig bekannte Protisten. XV. Arch. 

Protist., 50:486. 
Smith, T. : (1895) An infectious disease among turkeys caused by 

protozoa. Bull. Bur. Animal Ind., U. S. Dep. Agr., no. 8. 

(1910) Amoeba meleagridis. Science, 32:509. 

(1915) Further investigations into the etiology of the proto- 
zoan disease of turkeys known as blackheads, etc. J. Med. Res., 

Tyzzer, E. E.: (1919) Developmental phases of the protozoan of 

"blackhead" in turkeys. Ibid., 40:1. 
(1920) The flagellate character and reclassification of the 

parasite producing "blackhead" in turkey, etc. J. Parasit., 6: 

(1934) Studies on histomoniasis, etc. Proc. Am. Acad. Arts Sc, 

and Fabyan, M.: (1920) Further studies on "blackhead" in 

turkeys, etc. J. Infect. Dis., 27:207. 

(1922) A further inquiry into the source of the virus 

in blackhead of turkeys, etc. J. Exper. Med., 35:791. 
Wenrich, D. H.: (1943) Observations on the morphology of Histo- 
monas from pheasants and chickens. J. Morphol., 72:279. 

Chapter 14 
Order 2 Protomonadina Blochmann 

THE protomonads possess one or two flagella and are composed 
of a heterogeneous lot of Protozoa, mostly parasitic, whose af- 
finities to one another are very incompletely known. The body is in 
many cases plastic, having no definite pellicle, and in some forms 
amoeboid. The method of nutrition is holozoic, or saprozoic (para- 
sitic). Reproduction is, as a rule, by longitudinal fission, although 
budding or multiple fission has also been known to occur, while 
sexual reproduction, though reported in some forms, has not been 

With 1 flagellum 
With collar 

Collar enclosed in jelly Family 1 Phalansteriidae 

Collar not enclosed in jelly 

Without lorica Family 2 Codosigidae 

With lorica Family 3 Bicosoecidae (p. 341) 

Without collar 

Free-living Family 4 Oikomonadidae (p. 343) 

Parasitic Family 5 Trypanosomatidae (p. 344) 

With 2 flagella 

With undulating membrane Family 6 Cryptobiidae (p. 357) 

Without undulating membrane 

Flagella equally long Family 7 Amphimonadidae (p. 358) 

Flagella unequally long 

No trailing flagellum Family 8 Monadidae (p. 360) 

One flagellum trailing Family 9 Bodonidae (p. 362) 

Family 1 Phalansteriidae Kent 

Genus Phalansterium Cienkowski. Small, ovoid ; one flagellum and 
a small collar; numerous individuals are embedded in gelatinous 
substance, with protruding flagella; fresh water. 

P. digitatum Stein (Fig. 138, a). Cells about 17ju long; oval; colony 
dendritic; fresh water among vegetation. 

Family 2 Codosigidae Kent 

Small flagellates; delicate collar surrounds flagellum; ordinarily 
sedentary forms; if temporarily free, organisms swim with flagellum 
directed backward; holozoic on bacteria or saprozoic; often colonial; 
free-living in fresh water. Feeding process (Lapage, 1925). 

Genus Codosiga Kent (Codonocladium Stein; Astrosiga Kent). In- 
dividuals clustered at end of a simple or branching stalk ; fresh water. 




C. utriculus Stokes (Fig. 138, b). About 11/x long; attached to fresh- 
water plants. 

C. disjuncta (Fromentel) (Fig. 138, c). In stellate clusters; cells 
about 15ju long; fresh water. 

Fig. 138. a, Phalansterium digitatum, X540 (Stein); b, Codosiga 
utriculus, X1340 (Stokes); c, C. disjuncta, X400 (Kent); d, Monosiga 
ovata, X800 (Kent); e, M. robusta, X770 (Stokes); f. Desmarella monili- 
formis, X800 (Kent); g, Protospongia haeckeli, X400 (Lemmermann) ; 
h, an individual of Sphaeroeca volvox, X890 (Lemmermann); i, Diplosiga 
francei, X400 (Lemmermann); j, D. socialis, X670 (France^. 

Genus Monosiga Kent. Solitary; with or without stalk; occasion- 
ally with short pseudo podia; attached to freshwater plants. Several 

M. ovata K. (Fig. 138, d). 5-15/x long; with a short stalk. 

M. robusta Stokes (Fig. 138, e). 13m long; stalk very long. 

Genus Desmarella Kent. Cells united laterally to one another; 
fresh water. 

D. moniliformis K. (Fig. 138,/). Cells about 6ju long; cluster com- 
posed of 2-12 individuals; standing fresh water. 

D. irregularis Stokes. Cluster of individuals irregularly branching, 
composed of more than 50 cells; cells 7-1 1m long; pond water. 


Genus Proterospongia Kent. Stalkless individuals embedded irreg- 
ularly in a jelly mass, collars protruding; fresh water. 

P. haeckeli K. (Fig. 138, g). Body oval; 8m long; flagellum 24-32ju 
long; 6-60 cells in a colony. 

Genus Sphaeroeca Lauterborn. Somewhat similar to the last 
genus; but individuals with stalks and radiating; gelatinous mass 
spheroidal; fresh water. 

S. volvox L. (Fig. 138, h) . Cells ovoid, 8-12ju long; stalk about 
twice as long; flagellum long; contractile vacuole posterior; colony 
82-200> in diameter; fresh water. 

Genus Diplosiga Frenzel {Codonosigopsis Senn). With 2 collars; 
without lorica; a contractile vacuole; solitary or clustered (up to 4); 
fresh water. 

D. francei Lemmermann (Fig. 138, i). With a short pedicel; 12ju 
long; flagellum as long as body. 

D. socialis F. (Fig. 138, j). Body about 15/x long; usually 4 clus- 
tered at one end of stalk (15ju long). 

Family 3 Bicosoecidae Poche 

Small monomastigote; with lorica; solitary or colonial; collar may 
be rudimentary; holozoic; fresh water. Taxonomy and morphology 
(Grasse and Deflandre, 1952). 

Genus Bicosoeca James-Clark. With vase-like lorica; body small, 
ovoid with rudimentary collar, a flagellum extending through it; 
protoplasmic body anchored to base by a contractile filament 
(flagellum?); a nucleus and a contractile vacuole; attached or free- 

B. socialis Lauterborn (Fig. 139, a). Lorica cylindrical, 23/x by 
12^; body about 10> long; often in groups; free-swimming in fresh 

B. kepneri Reynolds. Body pyriform: 10m by 6m; lorica about 1.5 
times the body length; flagellum about 30m long (Reynolds, 1927). 

Genus Salpingoeca James-Clark. With a vase-like chitinous lorica 
to which stalked or stalkless organism is attached; fresh or salt 
water. Numerous species (Pascher, 1925, 1929). Morphology (Hofe- 
neder, 1925). 

S. fusiformis Kent (Fig. 139, 6). Lorica short vase-like, about 15- 
16m long; body filling lorica; flagellum as long as body; fresh water. 

Genus Diplosigopsis France. Similar to Diplosiga but with 
lorica; solitary; fresh water on algae. 

D. affinis Lemmermann (Fig. 139, c). Chitinous lorica, spindle- 
form, about 15^ long; body not filling lorica; fresh water. 



Genus Histiona Voigt. With lorica; but body without attaching 
filament; anterior end with lips and sail-like projection; fresh water. 
Morphology (Pascher, 1943). 

H. zachariasi V. (Fig. 139, d). Lorica cup-like; without stalk; 
about 13/a long; oval body 13/x long; flagellum long; standing fresh 

Genus Poteriodendron Stein. Similar to Bicosoeca; but colonial; 

Fig. 139. a, Bicosoeca socialis, X560 (Lauterborn); b, Salpingoeca 
fusiformis, X400 (Lemmermann); c, Diplosigopsis affinis, X590 (France^; 
d, Histiona zachariasi, X440 (Lemmermann); e, Poteriodendron petiola- 
tunij X440 (Stein); f, Codonoeca inclinata, X540 (Kent); g, Lagenoeca 
ovata, X400 (Lemmermann). 

lorica vase-shaped: with a prolonged stalk; fresh water. Flagellar 
movement (Geitler, 1942). 

P. petiolatum (S.) (Fig. 139, e). Lorica 17-50^ high; body 21-35/t 
long; flagellum twice as long as body; contractile vacuole terminal; 
standing fresh water. 

Genus Codonoeca James-Clark. With a stalked lorica; a single 
flagellum; 1-2 contractile vacuoles; fresh or salt water. 

C. inclinata Kent (Fig. 139, /). Lorica oval; aperture truncate; 
about 23m long; stalk twice as long; body oval, about 17m long; 
flagellum 1.5 times as long as body; contractile vacuole posterior; 
standing fresh water. 

Genus Lagenoeca Kent. Resembles somewhat Salpingoeca; with 
lorica; but without any pedicel between body and lorica; solitary; 
free-swimming; fresh water. 

L. ovata Lemmermann (Fig. 139, g). Lorica oval, 15/x long; body 
loosely filling lorica; flagellum 1.5 times body length; fresh water. 

Genus Stelexomonas Lackey. A single collar longer than body; 



vesicular nucleus median; a contractile vacuole terminal; individuals 
are enclosed in arboroid, dichotomously branching tubes; fresh 

S. dichotoma L. (Fig. 140, a). Body ovoid, 10m by 8m; flagellum up 
to 25/x long; collar 12m long; the dichotomous tube infolded and 
wrinkled where branched; organisms are not attached to the tube 
(Lackey, 1942). 

Fig. 140. a, Stelexomonas dichotoma, X1000 (Lackey); b, Oikomonas 
termo, X1330 (Lemmermann) ; c, Thylacomonas compressa, X640 (Lem- 
mermann); d, Ancyromonas contorta, X2000 (Lemmermann); e, Platy- 
theca microspora, X650 (Stein): f, Aulomonas purdyi, X1000 (Lackey); 
g, Caviomonas mobilis, X2400 (Nie). 

Family 4 Oikomonadidae Hartog 

Genus Oikomonas Kent. A rounded monomastigote; uninucleate; 
encystment common; stagnant water, soil and exposed faecal mat- 
ter. Several workers note the affinity of the members of this genus 
with Chrysomonadina, on the basis of general structure, cyst, etc., 
though lacking chromatophores. Owen (1949) points out the flagel- 
lum of Oikomonas is a simple one, typical of Chrysomonadina. 

0. termo (Ehrenberg) (Fig. 140, b). Spherical or oval; anterior end 
lip-like; flagellum about twice body length; a contractile vacuole; 
5-20m in diameter; stagnant water. Bacteria-free culture (Hardin, 
1942); bacterial food (Hardin, 1944, 1944a). 

Genus Thylacomonas Schewiakoff. Pellicle distinct; cytostome 


anterior; one flagellum; contractile vacuole anterior; rare. 

T. compressa S. (Fig. 140, c). 22/u by 18/x; flagellum body length; 
fresh water. 

Genus Ancyromonas Kent. Ovate to triangular; free-swimming or 
adherent; flagellum trailing, adhesive or anchorate at its distal end, 
vibratile throughout remainder of its length; nucleus central; a 
contractile vacuole; fresh or salt water. 

A. contorta (Klebs) (Fig. 140, d). Triangular, flattened; posterior 
end pointed; 6-7/z by 5-6/n; flagellum short; a contractile vacuole; 
standing fresh water. 

Genus Platytheca Stein. With a flattened pyriform lorica, with a 
small aperture; 1 or more contractile vacuoles; fresh water. 

P. microspora S. (Fig. 140, e). Lorica yellowish brown, with a 
small aperture; 12-18/x long; flagellum short; among roots of Lemna. 

Genus Aulomonas Lackey. Solitary and colorless; enclosed in, but 
not attached to, a thin hyaline cylindrical tube, which expands like a 
funnel at one end and broken at the other end; fresh water. 

A. purdyi L. (Fig. 140,/). Ovoid, 6-8ju by 4-5/x; flagellum 10-16m 
long; nucleus median; one contractile vacuole at each end of the 
body (Lackey, 1942). 

Genus Caviomonas Nie. Elongate pyriform; a single flagellum 
from the rounded anterior end where a vesicular nucleus is located; 
a band-like "peristyle" runs along the body; without cytostome; 
parasitic. One species (Nie, 1949). 

C. mobilis N. (Fig. 140, g). Body 2.2-6.6/x by 2-3m; average 4/x by 
3ju; in addition to the peristyle, a short, fine spinous strand occurs; 
in the caecal contents of guinea-pig, Cavia porcella. 

Family 5 Trypanosomatidae Doflein 

Body characteristically leaf-like, though changeable to a certain 
extent; a single nucleus and a blepharoplast from which a flagellum 
arises (Figs. 9; 141); basal portion of the flagellum forms the 
outer margin of undulating membrane which extends along one side 
of body; exclusively parasitic; a number of important parasitic 
Protozoa which are responsible for serious diseases of man and 
domestic animals in various parts of the world are included in it. 
Morphology and taxonomy (Grass6, 1952). 

Genus Trypanosoma Gruby. Parasitic in the circulatory system of 
vertebrates; highly flattened, pointed at flagellate end, and bluntly 
rounded, or pointed, at other; polymorphism due to differences in 
development common; nucleus central; near aflagellate end, there is 
a blepharoplast from which the flagellum arises and runs toward 



opposite end, marking the outer boundary of the undulating 
membrane; in most cases fiagellum extends freely beyond body; 
many with myonemes; multiplication by binary or multiple fission. 
The organism is carried from host to host by blood-sucking in- 
vertebrates and undergoes a series of changes in the digestive system 
of the latter (Fig. 142). A number of forms are pathogenic to their 
hosts and the diseased condition is termed trypanosomiasis in general. 

In vertebrate 

In invertebrate host 

In vertebrate 
















Leptomonas and 
Phytomonas (in plant) 





Fig. 141. Diagram illustrating the morphological differences among the 
genera of Trypanosomatidae (Wenyon) 

T. gambiense Dutton (Fig. 143, a-d). The trypanosome, as it oc- 
curs in the blood, lymph or cerebro-spinal fluid of man, is extremely 
active; body elongate, tapering towards both ends and sinuous; 15- 
30/i by 1-3 ju; the small blepharoplast is located near the posterior 
end; fiagellum arises from the blepharoplast and runs forward along 
the outer border of somewhat spiral undulating membrane, extend- 
ing freely; binary fission; between long (dividing) and short (recently 
divided) forms, various intermediates occur; in man in central Africa. 

No other stages are found in the human host. When a "tse-tse" 
fly, Glossina palpalis or G. tachinoides, sucks the blood of an in- 
fected person, the trypanosomes remain in its stomach for a few 
days and undergo multiplication which produces flagellates of 
diverse size and form until the 7th to 10th days when the organisms 
show a very wide range of forms. From 10th to 12th days on, long 



slender forms appear in great numbers and these migrate back gradu- 
ally towards proventriculus in which they become predominant 
forms. They further migrate to the salivary glands and attach them- 

Fig. 142. The life-cycle of Trypanosoma lewisi in the flea, Ceratophyl- 
lus fasciatus (Minchin and Thomson, modified), a, trypanosome from 
rat's blood; b, individual after being in flea's stomach for a few hours; 
o-l, stages in intracellular schizogony in stomach epithelium; m-r, two 
ways in which rectal phase may arise from stomach forms in rectum; 
s, rectal phase, showing various types; t, secondary infection of pylorus of 
hind-gut, showing forms similar to those of rectum. 



selves to the duct-wall in crithidia form. Here the development con- 
tinues for 2-5 days and the flagellates finally transform themselves 
into small trypanosomes which are now infective. These metacyclic 
trypanosomes pass down through the ducts and hypopharynx. When 
the fly bites a person, the trypanosomes enter the victim. In addition 
to this so-called cyclic transmission, mechanical transmission may 
take place. 

Trypanosoma gambiense is a pathogenic protozoan which causes 
Gambian or Central African sleeping sickness. The disease occurs in, 

Fig. 143. a-d, Trypanosoma gambiense; e-h, T. rhodesiense, in stained 
blood smears of experimental rats, X2300. An erythrocyte of rat is shown 
for comparison, a, b, typical forms; c, d, division stages; e, f, typical forms; 
g, h, post-nuclear forms. 

and confined to, central Africa within a zone on both sides of the 
equator where the vectors, Glossina palpalis and G. tachinoides (on 
the west coastal region) live. Many wild animals have been found 
naturally infected by the organisms and are considered to be reser- 
voir hosts. Among the domestic animals, the pigs appear to be one 
of the most significant, as they themselves are said not to suffer from 

The chief lesions of infection are in the lymphatic glands and in 
the central nervous system. In all cases, there is an extensive small- 



cell infiltration of the perivascular lymphatic tissue throughout the 
central nervous system. 

T. rhodesiense Stephens and Fantham (Fig. 143, e-h). Morphologi- 
cally similar to T. gambiense, but when inoculated into rats, the posi- 
tion of the nucleus shifts in certain proportion (usually less than 5%) 
of individuals toward the posterior end, near or behind the blepharo- 
plast, together with the shortening of body. Some consider this 
trypanosome as a virulent race of T. gambiense or one transmitted 
by a different vector, others consider it a human strain of T. brucei. 

The disease caused by this trypanosome appears to be more 
virulent and runs a course of only a few months. It is known as 
Rhodesian or East African sleeping sickness. The organism is con- 
fined to south-eastern coastal areas of Africa and transmitted by 
Glossina morsitans. 

T. cruzi Chagas (Schizotrypanum cruzi C). (Fig. 144). A small 

Fig. 144. Trypanosoma cruzi in experimental rtas. a-c, flagellate forms 
in blood; d, e, cytozoic forms, all X2300; f, a portion of infected cardiac 
muscle, X900. 

curved (C or U) form about 20m long; nucleus central; blepharoplast 
conspicuously large, located close to sharply pointed non-flagellate 
end; multiplication takes place in the cells of nearly every organ of 
the host body; upon entering a host cell, the trypanosome loses its 
flagellum and undulating membrane, and assumes a leishmania form 
which measures 2 to by. in diameter; this form undergoes repeated 
binary fission, and a large number of daughter individuals are pro- 
duced; they develop sooner or later into trypanosomes which, 
through rupture of host cells, become liberated into blood stream. 
Life cycle (Elkeles, 1951). 

This trypanosome is the causative organism of Chagas' disease or 
South American trypanosomiasis which is mainly a children's dis- 
ease, and is widely distributed in South and Central America and as 


far north as Mexico in North America. In the infected person, the 
heart and skeletal muscles show minute cyst-like bodies. 

The transmission of the organism is carried on apparently by nu- 
merous species of reduviid bugs, bed bugs and certain ticks, though 
the first named bugs belonging to genus Triatoma (cone-nosed or 
kissing bugs) especially T. megista (Panslrongylus megistus), are the 
chief vectors. When P. megistus (nymph or adult) ingests the in- 
fected blood, the organisms undergo division in the stomach and 
intestine, and become transformed into crithidia forms which con- 
tinue to multiply. In eight to 10 days the metacyclic or infective 
trypanosomes make their appearance in the rectal region and pass 
out in the faeces of the bug at the time of feeding on host. The para- 
sites gain entrance to the circulatory system when the victim 
scratches the bite-site or through the mucous membrane of the eye 
(Brumpt, 1912; Denecke and von Haller, 1939; Weinstein and Pratt, 

Cats, dogs, opossums, monkeys, armadillos, bats, foxes, squirrels, 
wood rats, etc., have been found to be naturally infected by T. cruzi, 
and are considered as reservoir hosts. Vectors are also numerous. 

No cases of Chagas' disease have been reported from the United 
States, but Wood (1934) found a San Diego wood rat (Neotoma 
fuscipes macrotis) in the vicinity of San Diego, California, in- 
fected by Trypanosoma cruzi and Packchanian (1942) observed in 
Texas, 1 nine-banded armadillo (Dasypis novemcinctus) , 8 opossums 
(Didelphys virginiana), 2 house mice (Mus musculus), and 32 wood 
rats {Neotoma micropus micropus), naturally infected by Trypano- 
soma cruzi. It has now become known through the studies of Kofoid, 
Wood, and others that Triatoma protracta (California, New Mex- 
ico), T. rubida (Arizona, Texas), T. gerstaeckeri (Texas), T. heide- 
manni (Texas), T. longipes (Arizona), etc., are naturally infected 
by T. cruzi. Wood and Wood (1941) consider it probable that 
human cases of Chagas' disease may exist in southwestern United 
States. In fact, the organisms from a naturally infected Triatoma 
heidemanni were shown by Packchanian (1943) to give rise to a 
typical Chagas' disease in a volunteer. Reduviid bugs (Usinger, 
1944) ; Chagas' disease in the United States (Packchanian, 1950) ; in 
central Brazil (Dias, 1949). 

T.brucei Plimmer and Bradford (Fig. 145, a). Polymorphic; 
15-30ju long (average 20/x); transmitted by various species of tsetse 
flies, Glossina; the most virulent of all trypanosomes; the cause of 
the fatal disease known as "nagana" among mules, donkeys, horses, 
camels, cattle, swine, dogs, etc., which terminates in the death of 



the host animal in from two weeks to a few months; wild animals 
are equally susceptible; the disease occurs, of course, only in the 
region in Africa where the tsetse flies live. 

T. theileri Laveran (Fig. 145, b). Large trypanosome which oc- 
curs in blood of cattle; sharply pointed at both ends; 60-7 0/t long; 
myonemes are well developed. Cytology (Hartmann and Noller, 

T. americanum Crawley. In American cattle; 17-25/u or longer; 
only crithidia forms develop in culture. Crawley (1909, 1912) found 
it in 74 per cent and Glaser (1922a) in 25 per cent of cattle they 
examined. The latter worker considered that this organism was an 
intermediate form between Trypanosoma and Crithidia. 

Fig. 145. a, Trypanosoma brucei; b. T. theileri; c, T. melophagium ; 
d, T. evansi; e, T. equinum; f, T. equiperdum; g, T. lewisi; all X1330 
(several authors). 

T. melophagium (Flu) (Fig. 145, c). A trypanosome of the sheep; 
50-60m long with attenuated ends; transmitted by Melophagus 

T. evansi (Steel) (Fig. 145, d). In horses, mules, donkeys, cattle, 
dogs, camels, elephants, etc.; infection in horses seems to be usually 
fatal and known as "surra"; about 25/x long; monomorphic; trans- 
mitted by tabanid flies; widely distributed. Transmission (Nieschulz, 

T. equinum Vages (Fig. 145, e). In horses in South America, caus- 
ing an acute disease known as "mal de Caderas"; other domestic 
animals do not suffer as much as do horses; 20-25/* long; without 


T. equiperdum Doflein (Fig. 145, /). In horses and donkeys; 
causes "dourine," a chronic disease; widely distributed; 25-30> 
long; no intermediate host; transmission takes place directly from 
host to host during sexual act. Nuclear division (Roskin and Schisch., 

T. hippicum Darling. In horses and mules in Panama; the cause 
of "murrina" or "derrengadera"; 16-18/x long; posterior end obtuse; 
mechanically transmitted by flies; experimentally various domestic 
and wild animals are susceptible, but calf is refractory (Darling, 
1910, 1911). Serological tests (Taliaferro and Taliaferro, 1934). 

T. lewisi (Kent) (Figs. 142; 145, g). In the blood of rats; widely 
distributed; about 30m long; body slender with a long flagellum; 
transmitted by the flea Ceratophyllus fasciatus, in which the organism 
undergoes multiplication and form change (Fig. 142); when a rat 
swallows freshly voided faecal matter of infected fleas containing 
the metacyclic organisms, it becomes infected. Many laboratory 
animals are refractory to this trypanosome, but guinea pigs are 
susceptible (Laveran and Mesnil, 1901: Coventry, 1929). Variation 
and inheritance of size (Taliaferro, 1921, 1921a, 1923); reproduction- 
inhibiting reaction product (Taliaferro, 1924, 1932) ; nuclear division 
(Wolcott, 1952). 

T. neotomae Wood (? T. triatomae Kofoid and McCulloch). In 
wood rats, Neotoma fuscipes annectens and N. f. macrotis; resembles 
T. lewisi; about 29m long; blepharoplast large, rod-form; free flagel- 
lum relatively short; the development in the vector flea Orchopeas 
W. wickhami, similar to that of T. lewisi; experimentally Norway 
rats are refractory (and wood rats are refractory to T. lewisi (Fae D. 
Wood, 1936)); comparative morphology of trypanosomes which oc- 
cur in California rodents and shrews (Davis, 1952). 

T. duttoni Thiroux. In the mouse; similar to T. lewisi, but rats are 
said not to be susceptible, hence considered as a distinct species; 
transmission by fleas. Antibodies (Taliaferro, 1938). 

T. peromysci Watson. Similar to T. lewisi; in Canadian deer mice, 
Peromyscus maniculatus and others. 

T. nabiasi Railliet. Similar to T. lewisi; in rabbits, Lepus do- 
mesticus and L. cuniculus. 

T. paddae Laveran and Mesnil. In Java sparrow, Munia oryzi- 

T. noctuae (Schaudinn). In the owl Athene noctua. 
Numerous other species occur in birds (Novy and MacNeal, 1905; 
Laveran and Mesnil, 1912; Wenyon, 1926). Crocodiles, snakes and 
turtles are also hosts for trypanosomes (Roudabush and Coatney, 



1937). Transmission is by blood-sucking arthropods or leeches. 

T. rotatorium (Mayer) (Fig. 146, a). In tadpoles and adults of 
various species of frog; between a slender form with a long projecting 
flagellum measuring about 35/x long and a very broad one without 
free portion of flagellum, various intermediate forms are to be 
noted in a single host; blood vessels of internal organs, such as kid- 
neys, contain more individuals than the peripheral vessels; nucleus 
central, hard to stain; blepharoplast small; undulating membrane 

Fig. 146. a, Trypanosoma rotatorium X750 (Kudo); b, T. inopinatum, 
X1180 (Kudo); c, T. diemyctyli, XSOO (Hegner); d, T. giganteum, 
X500 (Neumann); e, T. granulosum, XlOOO (Minchin); f, T. remaki, 
X1650 (Kudo); g, T. percae, XlOOO (Minchin); h, T. danilewskyi, 
XlOOO (Laveran and Mesnil); i, T. rajae, X1600 (Kudo). 

highly developed; myonemes prominent; multiplication by longi- 
tudinal fission; the leech, Placobdella marginata, has been found to 
be the transmitter in some localities 

T. inopinatum Sergent and Sergent (Fig. 146, b). In blood of vari- 
ous frogs; slender; 12-20/x long; larger forms 30-35/z long; blepharo- 
plast comparatively large; transmitted by leeches. 

Numerous species of Trypanosoma have been reported from the 
frog, but specific identification is difficult; it is better and safer 
to hold that they belong to one of the 2 species mentioned above 
until their development and transmission become known. 

T. diemyctyli Tobey (Fig. 146, c). In blood of the newt, Triturus 
viridescens ; a comparatively large form; slender; about 50ju by 2-5ju; 
flagellum 20-25/n long; with well developed undulating membrane. 


Both fresh and salt water fish are hosts to different species of 
trypanosomes; what effect these parasites exercise upon the host 
fish is not understood; as a rule, only a few individuals are ob- 
served in the peripheral blood of the host. Transmission (Robertson, 
1911); species (Laveran and Mesnil, 1912; Wenyon, 1926; Laird, 

T. granulosumL&ver&n and Mesnil (Fig. 146, e). In the eel, Anguilla 
vulgaris; 70-80> long. 

T. giganteum Neumann (Fig. 146, d). In Raja oxyrhynchus; 125- 
130^ long. 

T. remaki Laveran and Mesnil (Fig. 146, /). In Esox lucius, E. 
reticulatus and probably other species; 24-33/x long. (Kudo, 1921). 

T. percae Brumpt (Fig. 146, g). In Perca fluviatilis; 45-50> long. 

T. danilewskyi Laveran and Mesnil (Fig. 146, h). In carp and 
goldfish; widely distributed; 40> long. 

T. rajae Laveran and Mesnil (Fig. 146, i). In various species of 
Raja; 30-35/x long (Kudo, 1923). 

Genus Crithidia Leger. Parasitic in arthropods and other inverte- 
brates; blepharoplast located between central nucleus and flagellum- 
bearing end (Fig. 141); undulating membrane not so well developed 
as in Trypanosoma; it may lose the flagellum and form a leptomonas 
or rounded leishmania stage which leaves host intestine with faecal 
matter and becomes the source of infection in other host animals. 

C. euryophthalmi McCulloch (Fig. 147, a-c). In gut of Eury- 
ophthalmus convivus; California coast. 

C. gerridis Patton (Fig. 147, d). In intestine of water bugs, Gerris 
and Microvelia; 22-45^ long. Becker (1923) saw this in Gerris re- 

C. hyalommae O'Farrell (Fig. 147, e, /). In body cavity of the 
cattle tick, Hyalomma aegyptium in Egypt; the flagellate through 
its invasion of ova is said to be capable of infecting the offspring 
while it is still in the body of the parent tick. 

Genus Leptomonas Kent. Exclusively parasitic in invertebrates; 
blepharoplast very close to flagellate end ; without undulating mem- 
brane (Fig. 141); non-flagellate phase resembles Leishmania. 

L. ctenocephali Fantham (Fig. 147, g, h). In hindgut of the dog 
flea, Ctenocephalus canis; widely distributed. Morphology (Yama- 
saki, 1924). 

Genus Phytomonas Donovan. Morphologically similar to Lep- 
tomonas (Fig. 141); in the latex of plants belonging to the families 
Euphorbiaceae, Asclepiadaceae, Apocynaceae, Sapotaceae and 
Utricaceae; transmitted by hemipterous insects; often found in 



enormous numbers in localized areas in host plant; infection spreads 
from part to part; infected latex is a clear fluid, owing to the absence 
of starch grains and other particles, and this results in degeneration 
of the infected part of the plant. Several species. 

P. davidi (Lafront). 15-20> by about 1.5/z; posterior portion of 
body often twisted two or three times; multiplication by longitu- 
dinal fission; widely distributed; in various species of Euphorbia. 

P. elmassiani (Migone) (Fig. 147, i, j). In various species of milk 

Fig. 147. a-c, Crithidia euryophthalmi (a, b, in mid-gut; c, in rectum), 
X880 (McCulloch); d, C. gerridis, X1070 (Becker); e, f, C. hyalom- 
mae, X1000 (O'Farrell); g, h, Leptomonas ctenocephali, XlOOO (Wenyon); 
i, j, Phytomonas elmassiani (i, in milkweed, Asclepias sp. ; j, in gut of a 
suspected transmitter, Oncopeltus fasciatus), X1500 (Holmes); k, 
Herpetomonas muscarum, X1070 (Becker); 1-n, H. drosophilae, XlOOO 
(Chatton and Leger). 

weeds; 9-20/x long; suspected transmitter, Oncopeltus fasciatus 
(Holmes, 1924); in South and North America. 

Genus Herpetomonas Kent. Ill-defined genus (Fig. 141); ex- 
clusively invertebrate parasites; Trypanosoma-, Crithidia-, Lep- 
tomonas-, and Leishmania-forms occur during development. Several 
species. Species in insects (Drbohlav, 1925). 

H. muscarum (Leidy) (H. muscae-domeslicae Burnett) (Fig. 147, k). 
In the digestive tube of flies belonging to the genera: Musca, Cal- 
liphora, Cochliomyia, Sarcophaga, Lucilia, Phormia, etc.; up to 30ju 
by 2-3/x. Effect on experimental animals (Glaser, 1922) ; comparative 
study (Becker, 1923a). 

H. drosophilae (Chatton and Alilaire) (Fig. 147, l-n). In intestine 
of Drosophila confusa; large leptomonad forms 21-25/u long, flagel- 
lum body-length; forms attached to rectum 4-5m long. 


Genus Leishmania Ross. In man or dog, the organism is an ovoid 
body with a nucleus and a blepharoplast; 2-5;u in diameter; with 
vacuoles and sometimes a rhizoplast near the blepharoplast; intra- 
cellular parasite in the cells of reticuloendothelial system; multi- 
plication by binary fission. In the intestine of blood-sucking insects 
or in blood-agar cultures, the organism develops into leptomonad 
form (Fig. 148, d-j) which multiplies by longitudinal fission. Nuclear 
division (Roskin and Romanowa, 1928). 

There are known at present three "species" of Leishmania which 
are morphologically alike. They do not show any distinct differential 
characteristics either by animal inoculation experiments or by cul- 
ture method or agglutination test. 

Species of Phlebotomus (sand-flies) have long been suspected as 
vectors of Leishmania. When a Phlebotomus feeds on kala-azar 
patient, the leishmania bodies become flagellated and undergo 
multiplication so that by the third day after the feeding, there 
are large numbers of Leptomonas flagellates in the mid-gut. These 
flagellates migrate forward to the pharynx and mouth cavity on the 
4th or 5th day. On the 7th to 9th days (after the fly is fed a second 
time), the organisms may be found in the proboscis. But the great 
majority of the attempts to infect animals and man by the bite of 
infected Phlebotomus have failed, although in a number of cases 
small numbers of positive infection have been reported. Adler and 
Ber (1941) have finally succeeded in producing cutaneous leish- 
maniasis in 5 out of 9 human volunteers on the site of bites by lab- 
oratory-bred P. papatasii which were fed on the flagellates of 
Leishmania tropica suspended in 3 parts 2.7% saline and 1 part de- 
fib rinated blood and kept at a temperature of 30°C. Swaminath, 
Shortt and Anderson (1942) also succeeded in producing kala-azar 
infections in 3 out of 5 volunteers through the bites of infected P. 

L. donovani (Laveran and Mesnil) (L. infantum, Nicolle) (Fig. 148). 
As seen in stained spleen puncture smears, the organism is rounded 
(1-3/x) or ovoid (2— 4/x by 1.5-2.5/z); cytoplasm homogeneous, but 
often with minute vacuoles; nucleus comparatively large, often 
spread out and of varied shapes; blepharoplast stains more deeply 
and small; number of parasites in a host cell varies from a few to 
over 100. 

This is the cause of kala-azar or visceral leishmaniasis which is 
widely distributed in Europe (Portugal, Spain, Italy, Malta, Greece, 
and southern Russia), in Africa (Morocco, Algeria, Tunisia, Libya, 
Abyssinia, Sudan, northern Kenya and Nigeria), in Asia (India, 



China, Turkestan, etc.), and in South America. The parasite is most 
abundantly found in the macrophages, mononuclear leucocytes, and 
polymorphonuclears of the reticulo-endothelial system of various 
organs such as spleen, liver, bone marrow, intestinal mucosa, lym- 
phatic glands, etc. The most characteristic histological change ap- 
pears to be an increase in number of large macrophages and mono- 
nuclears. The spleen and liver become enlarged due in part to 
increased fibrous tissue and macrophages. 

Fig. 148. Leishmania donovani, X1535. a, an infected polymorpho- 
nuclear leucocyte; b, organisms scattered in the blood plasm; c, an in- 
fected monocyte; d-f, flagellate forms which develop in blood-agar cul- 

The organism is easily cultivated in blood-agar media (p. 886). 
After two days, it becomes larger and elongate until it measures 
14-20/z by 2/i. A flagellum as long as the body develops from the 
blepharoplast and it thus assumes leptomonad form (Fig. 148, /) 
which repeats longitudinal division. Dogs are naturally infected with 
L. donovani and may be looked upon as a reservoir host. Vectors are 
Phlebotomus argentipes and other species of Phlebotomus. 

L. tropica (Wright). This is the causative organism of the Oriental 
sore or cutaneous leishmaniasis. It has been reported from Africa 
(mainly regions bordering the Mediterranean Sea), Europe (Spain 
Italy, France, and Greece), Asia (Syria, Palestine, Armenia, South- 
ern Russia, Iraq, Iran, Arabia, Turkestan, India, Indo-China, and 
China), and Australia (northern Queensland). The organisms are 
present in the endothelial cells in and around the cutaneous lesions, 
located on hands, feet, legs, face, etc. 

L. tropica is morphologically indistinguishable from L. donovani, 
but some believe that it shows a wider range of form and size than 
the latter. In addition to rounded or ovoid forms, elongate forms are 


often found, and even leptomonad forms have been reported from 
the scrapings of lesions. The insect vectors are Phlebotomus papa- 
tasii (p. 355), P. scrgenti and others. Direct transmission through 
wounds in the skin also takes place. The lesion appears first as a 
small papula on skin; it increases in size and later becomes ulcerated. 
Microscopically an infiltration of corium and its papillae by lympho- 
cytes and macrophages is noticed; in ulcerated lesions leishmania 
bodies are found in the peripheral zone and below the floor of the 

L. brasiliensis Vianna. This organism causes Espundia, Bubos, or 
American or naso-oral leishmaniasis, which appears to be con- 
fined to South and Central America. It has been reported from 
Brazil, Peru, Paraguay, Argentina, Uruguay, Bolivia, Venezuela, 
Ecuador, Colombia, Panama, Costa Rica, and Mexico. 

Its morphological characteristics are identical with those of L. 
tropica, and a number of investigators combine the two species into 
one. However, L. brasiliensis produces lesions in the mucous mem- 
brane of the nose and mouth. Vectors appear to be Phlebotomus 
intermedins, P. panamensis and other species of the genus. Direct 
transmission through wounds is also possible. Fuller and Geiman 
(1942) find Citellus tridecemlineatus a suitable experimental animal. 

Family 6 Cryptobiidae Poche 

Biflagellate trypanosome-like pro to monads; 1 flagellum free, the 
other marks outer margin of undulating membrane; blepharoplast 
an elongated rod-like structure, often referred to as the parabasal 
body; all parasitic. 

Genus Cryptobia Leidy (Trypanoplasma Laveran and Mesnil). 
Parasitic in the reproductive organ of molluscs (Leidy, 1846) and 
other invertebrates; also in the blood of fishes. 

C. helicis L. (Fig. 149, a-c). In the reproductive organ of various 
species of pulmonate snails: Triodopsis albolabris, T. tridentata, 
Anguispira alternata (Leidy, 1846), Helix aspersa, and Monadenia 
fidelis (Kozloff, 1948); 16-26.5 M by 1.5-3.3/x. Morphology and cul- 
ture (Schindera, 1922). 

C. borreli (Laveran and Mesnil) (Fig. 149, d, e). In blood of various 
freshwater fishes such as Catostomus, Cyprinus, etc.; 20-25/x long 
(Mavor, 1915). 

C. cyprini (Plehn) (Fig. 149, /). In blood of carp and goldfish; 
10-30/z long; rare. 

C. grobbeni (Keysselitz). In coelenteric cavity of Siphonophora; 
about 65/x by 4/x. 



Family 7 Amphimonadidae Kent 

Body naked or with a gelatinous envelope; 2 equally long anterior 
flagella; often colonial; 1-2 contractile vacuoles; free-swimming or 
attached ; mainly fresh water. 

Genus Amphimonas Dujardin. Small oval or rounded amoeboid; 
flagella at anterior end; free-swimming or attached by an elongated 
stalk-like posterior process; fresh or salt water. 

Fig. 149. a, a neutral red stained and b, a fixed and stained Cryptobia 
helicis, X2200 (Kozloff); c, stained specimen of the same organism, 
X1690 (Belaf); d, a living and e, stained C. borreli, X1730 (Mavor); f, 
C. cyprini, X600 (Plehn). 

A. globosa Kent (Fig. 150, a). Spherical; about 13/x in diameter; 
stalk long, delicate; fresh water. 

Genus Spongomonas Stein. Individuals in granulated gelatinous 
masses; 2 flagella; one contractile vacuole; colonial; with pointed 
pseudopodia in motile stage; fresh water. 

S. uvella S. (Fig. 150, 6). Oval; 8-12/x long; flagella 2-3 times as 
long; colony about 50ju high; fresh water. 

Genus Cladomonas Stein. Individuals are embedded in dichot- 
omous dendritic gelatinous tubes which are united laterally; fresh 

C. fruticulosa S. (Fig. 150, c). Oval; about 8^ long; colony up to 
85ju high. 

Genus Rhipidodendron Stein. Similar to Cladomonas, but tubes 
are fused lengthwise ; fresh water. 



R. splendidum S. (Fig. 150, d, e). Oval; about 13m long; flagella 
about 2-3 times body length; fully grown colony 350/z high. 

Genus Spiromonas Perty. Elongate; without gelatinous covering; 
spirally twisted; 2 flagella anterior; solitary; fresh water. 

S. augusta (Dujardin) (Fig. 150,/). Spindle-form; about 10ju long; 
stagnant water. 

Fig. 150. a, Amphimonas globosa, X540 (Kent); b, Spongomonas uvella, 
X440 (Stein); c, Cladomonas fruticulosa, X440 (Stein); d, e, Rhipidoden- 
dron splendidum (d, a young colony, X440; e, a freeswimming individual, 
X770) (Stein); f, Spiromonas augusta, X1000 (Kent); g, Diplomita soci- 
alis, X1000 (Kent); h, Streptomonas cordata, X890 (Lemmermann) ; i, 
Dinomonas vorax, X800 (Kent). 

Genus Diplomita Kent. With transparent lorica; body attached 
to bottom of lorica by a retractile filamentous process; a rudimen- 
tary stigma (?) ; fresh water. 

D. socialis K. (Fig. 150, g). Oval flagellum about 2-3 times the 
body length; lorica yellowish or pale brown; broadly spindle in form; 
about 15ju long; pond water. 

Genus Streptomonas Klebs. Free-swimming; naked; distinctly 
keeled; fresh water. 

S. cordata (Perty) (Fig. 150, h). Heart-shaped; 15/u by 13/*; rota- 
tion movement, 


Genus Dinomonas Kent. Ovate or pyriform, plastic, free-swim- 
ming; 2 fiagella, equal or sub-equal, inserted at anterior extremity, 
where large oral aperture, visible only at time of food ingestion, is also 
located, feeding on other flagellates; in infusions. 

D. vorax K. (Fig. 150, i). Ovoid, anterior end pointed; 15-16ju. 
long; fiagella longer than body; hay infusion and stagnant water. 

Family 8 Monadidae Stein 

Two unequal fiagella; one primary and the other secondary; swim- 
ming or attached; 1-2 contractile vacuoles; colony formation fre- 
quent; free-living. 

Genus Monas Muller (Physomonas Kent). Active and plastic; 
often attached to foreign objects; small, up to 20m long; fresh and 
salt water. Some authors hold that this genus should be placed in 
Chrysomonadina on the same ground mentioned for Oikomonas (p. 
343). Flagellar movement (Krijgsman, 1925); cyst (Scherffel, 1924); 
morphology and taxonomy (Reynolds, 1934). 

M. guttula Ehrenberg (Fig. 151, a). Spherical to ovoid; 14-16m 
long; free-swimming or attached; longer flagellum about 1-2 times 
body length; cysts 12m in diameter; stagnant water. 

M. elongata (Stokes) (Fig. 151, b). Elongate; about 11m long; free- 
swimming or attached; anterior end obliquely truncate; fresh water. 

M. socialis (Kent) (Figs. 8, d; 151, c). Spherical; 5-10ju long; 
among decaying vegetation in fresh water. 

M. vestita (Stokes) (Fig. 151, d). Spherical; about 13.5m in diam- 
eter; stalk about 40m long; pond water. Reynolds (1934) made a 
careful study of the organism. 

M. sociabilis Meyer. Body 8-10ju long by 5m; two unequal fiagella; 
the longer one is as long as the body and the shorter one about one- 
fourth; 20-50 individuals form a spheroid colony, resembling a 
detached colony of Anthophysis; polysaprobic. 

Genus Stokesiella Lemmermann. Body attached by a fine cyto- 
plasmic thread to a delicate and stalked vase-like lorica; 2 contrac- 
tile vacuoles; fresh water. 

S. dissimilis (Stokes) (Fig. 151, e). Solitary; lorica about 28m long. 

S. leptostoma (S.) (Fig. 151, /). Lorica about 17m long; often in 
groups; on vegetation. 

Genus Stylobryon Fromentel. Similar to Stokesiella; but colonial ; 
on algae in fresh water. 

S. abbotti Stokes (Fig. 151, g). Lorica campanulate; about 17m 
long; main stalk about 100m high; body oval or spheroidal; fiagella 



Genus Dendromonas Stein. Colonial; individuals without lorica, 
located at end of branched stalks; fresh water among vegetation. 

D. virgaria (Weisse) (Fig. 151, h). About 8/1 long; colony 200/x 
high; pond water. 

Fig. 151. a, Monas guttula, X620 (Fisch); b, M. elongata, X670 
(Stokes); c, M. socialis, X670 (Kent); d, M. vestita, X570 (Stokes); 
e, Stokesiella dissimilis, X500 (Stokes); f, S. leptostoma, X840 (Stokes); 
g, Stylobryon abbotti, X480 (Stokes); h, Dendromonas virgaria, a young 
colony of, X670 (Stein); i, Cephalothamnium cyclopum, X440 (Stein); 
j, k, Anthophysis vegetans (j, part of a colony, X230; k, an individual, 
X770) (Stein). 

Genus Cephalothamnium Stein. Colonial; without lorica, but in- 
dividuals clustered at the end of a stalk which is colorless and rigid; 
fresh water. 

C. cyclopum S. (Fig. 151, i). Ovoid; 5-10/x long; attached to body 
of Cyclops and also among plankton. 

Genus Anthophysis Bory (Anthophysa). Colonial forms, some- 
what similar to Cephalothamnium; stalks yellow or brownish and 
usually bent ; detached individuals amoeboid with pointed pseudo- 

A. vegetans (Miiller) (Fig. 151, j, k). About 5-6m long; common in 
stagnant water and infusion. 


Family 9 Bodonidae Biitschli 

With 2 flagella; one directed anteriorly and the other posteriorly 
and trailing; flagella originate in anterior end which is drawn out 
to a varying degree; one to several contractile vacuoles; asexual re- 
production by binary fission; holozoic or saprozoic (parasitic). Mor- 
phology and taxonomy (Hollande, 1942, 1952). 

Genus Bodo Ehrenberg (Prowazekia Hartman and Chagas). 
Small, ovoid, but plastic; cytostome anterior; nucleus central or 
anterior; flagella connected with 2 blepharoplasts in some species; 
encystment common; in stagnant water and coprozoic. Numerous 
species. Cytology (Belaf, 1920; Hollande, 1936). 

B. caudatus (Dujardin) (Fig. 152, a, b). Highly flattened, usually 
tapering posteriorly; 11-22/x by 5-10>; anterior flagellum about 
body length, trailing flagellum longer; blepharoplast; cysts spherical; 
stagnant water. 

B. edax Klebs (Fig. 152, c). Pyriform with bluntly pointed ends; 
11— 15/x by 5-7m; stagnant water. 

Genus Pleuromonas Perty. Naked, somewhat amoeboid; usually 
attached with trailing flagellum; active cytoplasmic movement; 
fresh water. 

P. jaculans P. (Fig. 152, d). Body 6-10> by about 5/z; flagellum 
2-3 times body length; 4-8 young individuals are said to emerge 
from a spherical cyst; stagnant water. 

Genus Rhynchomonas Klebs (Cruzella Faria, da Cunha and 
Pinto). Similar to Bodo, but there is an anterior extension of body, 
in which one of the flagella is embedded, while the other flagellum 
trails; a single nucleus; minute forms; fresh or salt water; also some- 
times coprozoic. 

R. nasuta (Stokes) (Fig. 152, e). Oval, flattened; 5 6/u by 2-3/x; 
fresh water and coprozoic. 

R. marina (F., C. and P.). In salt water. 

Genus Proteromonas Kunstler (ProwazekeUa Alexeieff). Elon- 
gated pyriform; 2 flagella from anterior end, one directed anteriorly 
and the other, posteriorly; nucleus anterior; encysted stage is re- 
markable in that it is capable of increasing in size to a marked de- 
gree; exclusively parasitic; in gut of various species of lizards. Spe- 
cies (Grasse, 1926, 1952). 

P. lacertae (Grassi) (Fig. 152, /). Elongate, pyriform; 10-30> long, 
gut of lizards belonging to the genera Lacerta, Tarentola, etc. 

Genus Retortamonas Grassi {Embadomonas Mackinnon). Body 
plastic, usually pyriform or fusiform, drawn out posteriorly; a large 


cytostome toward anterior end; nucleus anterior; 2 flagella; cysts 
pyriform or ovoid; parasitic in the intestines of various animals. 
Taxonomy (Wenrich, 1932; Kirby and Honigberg, 1950). 

R. gryllotalpae G. (Fig. 152, g). About 7-14;u (average 10/x) long; 
in intestine of the mole cricket, Gryllotalpa gryllotalpa. 

Fig. 152. a, b, Bodo caudatus, X1500 (Sinton); c, B. edax, X1400 
(Kiihn); d, Pleuromonas jaculans, X650 (Lemmermann); e, Rhin- 
chomonas nasuta, X1800 (Parisi); f, Proteromonas lacertae, X2500 
(Ktihn); g, Retortamonas gryllotalpae, X2000 (Wenrich); h, R. blattae, 
X2000 (Wenrich); i, R. intestinalis, X2000 (Wenrich); j, Phijllomitus 
undulans, X1000 (Stein); k, Colponema loxodes, X650 (Stein); 1, Cerco- 
monas longicauda, X2000 (Wenyon); m, C. crassicauda, X2000 (Dobell). 

R. blattae (Bishop) (Fig. 152, h). About 6-9/x long; in colon of 

R. intestinalis (Wenyon and O'Connor) (Figs. 152, i; 153). Poly- 
morphic, often pyriform or ovoid with drawn-out posterior end; 4-9ju 
by 3-4ju; cytostome large, about 1/3 the body length ; vesicular nucleus 



with an endosome near anterior end; anterior flagellum as long as 
the body; posterior flagellum shorter, but thicker, in or near cyto- 
stome; cysts pyriform; 4.5-7/* long; a single nucleus and an oblong 
area surrounded by fibril; commensal in the lumen of human intes- 
tine; trophozoites and also cysts occur in diarrhoeic faeces; of com- 
paratively rare occurrence. Varieties (Hogue, 1933, 1936). 

R. caviae (Hegner and Schumaker, 1928). In the caecum of guinea- 
pigs; stained trophozoites 4-7 /* by 2.4-3.2/* (H. and S.), 4.4-7.7/* by 
4-4.3/* (Nie, 1950); stained cysts 3.4-5.2/* by 3.3-3.6/z (H. and S.), 
4.5-5.7/* by 3.4-3.7/* (Nie). 

Fig. 153. Retortamonas intestinalis, X2300 (a, b, d, Wenyon and 
O'Connor; c, Dobell and O'Connor; e, g, Kudo; f, Jepps). a, b, organ- 
isms in life; c, d, stained trophozoites; e, cyst in life; f, g, stained cysts. 

Genus Phyllomitus Stein. Oval; highly plastic; cytostome large 
and conspicuous; 2 unequal flagella, each originates in a blepharo- 
plast; fresh water or coprozoic. 

P. undulans S. (Fig. 152, j), Ovoid; 21-27/* long; trailing flagel- 
lum much longer than anterior one; stagnant water. 

Genus Colponema Stein. Body small; rigid; ventral furrow con- 
spicuous, wide at anterior end; one flagellum arises from anterior end 
and the other from middle of body; fresh water. 

C. loxodes S. (Fig. 152, k). 18-30/* by 14/* cytoplasm with refractile 

Genus Cercomonas Dujardin. Biflagellate, both flagella arising 
from anterior end of body; one directed anteriorly and the other 
runs backward over body surface, becoming a trailing flagellum; 
plastic; pyriform nucleus connected with the blepharoplast of 
flagella; spherical cysts uninucleate; fresh water or coprozoic. 


C. longicauda D. (Fig. 152, V). Pyriform or ovoid; posterior end 
drawn out; 18-36/x by 9-14ju; flagella as long as body; pseudo podia; 
fresh water and coprozoic. 

C. crassicauda D. (Fig. 152, m). 10-16ju by 7-10/*; fresh water and 


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by the bite of Phlebotomus papatasii. Indian J. Med. Research, 

Becker, E. R. : (1923) Observations on the morphology and life 

cycle of Crithidia gerridis, etc. J. Parasit., 9:141. 
(1923a) Observations on the morphology and life history of 

Herpelomonas muscae-domesticae in North American muscoid 

flies. Ibid., 9:199. 
Belar, K. : (1920) Die Kernteilung von Prowazekia. Arch. Protist., 

Brumpt, E.: (1912) Penetration du Schizotrypanum cruzi a travers 

la muqueuse oculaire saine. Bull. Soc. Path. Exot., 5:723. 
Coventry, F. A. : (1929) Experimental infections with Trypanosoma 

lewisi in the guinea pigs. Am. J. Hyg., 9:247. 
Crawley, H.: (1909) Studies on blood and blood parasites. I— III. 

Bull. Bur. Animal Ind., U. S. Dep. Agr., no. 119. 

(1912) Trypanosoma americanum, a common blood parasite 

of American cattle. Ibid., no. 145. 

Darling, S. T. : (1910) Equine trypanosomiasis in the canal zone. 
Bull. Soc. Path. Exot., 3:381. 

— (1911) Murrina: etc. J. Infect. Dis., 8:467. 

Davis, Betty S.: (1952) Studies on the trypanosomes of some Cali- 
fornia mammals. Univ. California Publ. Zool., 57:145. 

Denecke, K. and Haller, E. v.: (1939) Recherches experimentale 
sur le mode de transmission et le course de l'infection par 
Trypanosoma cruzi chez les souris. Ann. Parasit., 17:313. 

Dias, E. : (1949) Consideracoes sobre a doenca de Chagas. Mem. 
Inst. Oswaldo Cruz, 47:679. 

Drbohlav, J.: (1925) Studies on the relation of insect flagellates to 
Leishmaniasis. I— III. Am. J. Hyg., 5:580. 

Elkeles, G.: (1951) On the life cycle of Trypanosoma cruzi. J. 
Parasit., 37:379. 

Fuller, H. S. and Geiman, Q. M.: (1942) South American cutane- 
ous leishmaniasis in experimental animals. J. Parasit., 28:429. 

Geitler, L.: (1942) Beobachtungen liber die Geisselbewegung der 
Bicoecacee Poteriodendron. Arch. Protist., 96:119. 

Glaser, R. W.: (1922) Hcrpetomonas muscae-domesticae, its be- 
havior and effect in laboratory animals. J. Parasit., 8:99. 

— (1922a) A study of Trypanosoma americanum. Ibid., 8:136. 
Grasse, P.-P. : (1926) Contribution a l'etude des flagelles parasites. 

Arch. zool. exper. gen., 65:345. 

(1952) Traite de zoologie. I. Fasc. 1. Paris. 


and Deflandre, G. : (1952) Ordre des Bicoecidea. In: 

Grasse (1952), p. 599. 

Hardin, G.: (1942) An investigation of the physiological require- 
ments of a pure culture of the heterotrophic flagellate, Oiko- 
monas termo Kent. Physiol. Zool., 15:466. 

(1944) Physiological observations and their ecological sig- 
nificance: etc. Ecology, 25:192. 

(1944a) Symbiosis of Paramecium and Oikomonas. Ibid., 25: 

Hartmann, M. and Noller, W.: (1918) Untersuchungen ueber die 

Cytologic von Trypanosoma theileri. Arch. Protist., 38:355. 
Hegner, R. W. and Schumaker, E.: (1928) Some intestinal amoe- 
bae and flagellates from the chimpanzee, etc. J. Parasit., 15:31. 
Hofeneder, H. : (1925) Ueber eine neue Caspedomonadine. Arch. 

Protist., 51:192. 
Hogue, Mary J.: (1933) A new variety of Retortamonas intestinalis 

from man. Am. J. Hyg., 18:433. 

— (1936) Four races of Retortamonas intestinalis. Ibid., 23:80. 

Hollande, A.: (1936) Sur la cytologie d'un flagelle du genre Bodo. 

C. R. Soc. Biol., 123:651.' 
(1942) Etudes cytologique et biologique de quelques flagelles 

libres. Arch. zool. exper. gen., 83:1. 

(1952) Ordre des Bodonides. In: Grasse (1952), p. 669. 

Holmes, F. O.: (1924) Herpetomonad flagellates in the latex of 

milkweed in Maryland. Phytopathology, 14:146. 
■ — • (1925) The relation of Herpetomonas elmassiani to its plant 

and insect hosts. Biol. Bull., 49:323. 
Ivanic, M.: (1936) Zur Kenntnis der Entwicklungsgeschichte bei 

Mastigina hylae. Arch. Protist., 87:225. 
Kirby, H. and Honigberg, B.: (1950) Intestinal flagellates from a 

wallaroo, Macropus robustus. Univ. California Publ. Zool., 55: 

Kozloff, E. N.: (1948) The morphology of Cryptobia helicis. J. 

Morphol., 83:253. 
Kudo, R. R.: (1921) On some Protozoa parasitic in freshwater fishes 

of New York. J. Parasit., 7:166. 

(1923) Skate trypanosome from Woods Hole. Ibid., 9: 179. 

Lackey, J. B.: (1942) Two new flagellate Protozoa from the Ten- 
nessee River. Tr. Am. Micr. Soc, 61:36. 
Laird, M. : (1951) Studies on the trypanosomes of New Zealand fish. 

Proc. Zool. Soc, London, 121:285. 
Lapage, G.: (1925) Notes on the choanoflagellate, Codosiga botrytis. 

Quart. J. Micr. Sc, 69:471. 
Laveran, A. and Mesnil, F.: (1901) Sur les flagelles a membrane 

ondulante des poissons, etc. C. R. Acad. Sc, 133:670. 

(1912) Trypanosomes et trypanosomiases. 2 ed. 

Leidy, J.: (1846) Description of a new genus and species of Entozoa. 

Proc. Acad. Nat. Sc. Philadelphia, 3:100. 
Lemmermann, E.: (1914) Protomastiginae. Susswasserflora Deutsch- 

lands. H. 1. 


Mavor, J. W. : (1915) On the occurrence of a trypanosome, probably 
Trypanoplasma borreli, etc. J. Parasit., 2:1. 

Minchin, E. A. and Thomson, J. D.: (1915) The rat trypanosome, 
Trypanosoma lewisi, in its relation to the rat flea, etc. Quart. J. 
Micr.Sc, 60:463. 

Nelson, R. : (1922) The occurrence of Protozoa in plants affected 
with mosaic and related diseases. Tech. Bull. Bot. Stat. Michi- 
gan Agr. Coll., no. 58. 

Nie, D.: (1950) Morphology and taxonomy of the intestinal Proto- 
zoa of the guinea-pig, Cavia porcella. J. Morphol., 86:381. 

Nieschulz, O.: (1928) Zoologische Beitrage zum Surra problem. 
XVII. Arch. Protist., 61:92. 

Novy, F. G. and MacNeal, W. J.: (1905) On the trypanosomes of 
birds. J. Infect. Dis., 2:256. 

Packchanian, A.: (1942) Reservoir hosts of Chagas' disease in the 
State of Texas. Am. J. Trop. Med., 22:623. 

(1943) Infectivity of the Texas strain of Trypanosoma cruzi 

toman. Ibid., 23:309. 

(1950) The present status of Chagas' disease in the United 

States. Rev. Soc. Mexicana Hist. Nat., 10:91. 

Pascher, A.: (1925) Neue oder wenig bekannte Protisten. XVII. 
Arch. Protist., 51:549. 
(1929) XXI. Ibid., 65:426. 

— (1943) Eine neue Art der farblosen Flagellatengattung His- 
tiona aus den Uralpen. Ibid., 96:288. 

Reynolds, B. D.: (1927) Bicosoeca kepneri. Tr. Am. Micr. Soc, 

(1934) Studies on monad flagellates. I, II. Arch. Protist., 81 : 

Robertson, M.: (1911) Transmission of flagellates living in the 

blood of certain freshwater fishes. Philos. Trans., B, 202:29. 
Roskin, G. and Romanowa, K. : (1928) Die Kernteilung bei 

Leishmania tropica. Arch. Protist., 60:482. 
and Schischliaiewa, S.: (1928) Die Kernteilung bei Try- 

panosomen. Ibid., 60:460. 
Roudabush, R. L. and Coatney, G. R. : (1937) On some blood 

Protozoa of reptiles and amphibians. Tr. Am. Micr. Soc, 56: 

Scherffel, A.: (1924) Ueber die Cyste von Monas. Arch. Protist., 

Schindera, M.: (1922) Beitrage zur Biologie, Agglomeration und 

Ztichtung von Trypanoplasma helicis. Ibid., 45:200. 
Swaminath, C. S., Shortt, E. and Anderson, A. P.: (1942) Trans- 
mission of Indian kala-azar to man by the bites of Phlebotomus 

argentipes. Indian J. Med. Research, 30:473. 
Taliaferro, W. H.: (1921) Variation and inheritance in size in 

Trypanosoma lewisi. I. Proc Nat. Acad. Sc, 7:138. 

— (1921a) II. Ibid., 7:163. 

(1923) A study of size and variability, throughout the course 

of "pure line" infections, with Trypanosoma lewisi. J. Exper. 
Zool., 37:127. 


— (1924) A reaction product in infections with Trypanosoma 
lewisi which inhibits the reproduction of the trypanosomes. J. 
Exper. Med., 39:171. 

— (1926) Variability and inheritance of size in Trypanosoma 
lewisi. J. Exper. Zool., 43:429. 

— (1932) Trypanocidal and reproduction-inhibiting antibodies 
to Trypanosoma lewisi in rats and rabbits. Am. J. Hyg., 16:32. 

(1938) Ablastic and trypanocidal antibodies against Try- 

panosoma duttoni. J. Immunol., 35:303. 
— and Taliaferro, Lucy G.: (1934) Complement fixation, 
precipitin, adhesion, mercuric chloride and Wassermann tests in 
equine trypanosomiasis of Panama. Ibid., 26:193. 

Usinger, R. L.: (1944) The Triatominae of North and Central 
America and the West Indies and their public health signifi- 
cance. U. S. Publ. Health Bull., no. 288. 

Vianna, G.: (1911) Sobre uma nova especie de Leishmania. Brazil 
Medico, no. 41. 

Weinstein, P. P. and Pratt, H. D.: (1948) The laboratory infec- 
tion of Triatoma neotomae Neiva with Trypanosoma cruzi, etc. 
J. Parasit., 34:231. 

Wenrich, D. H.: (1932) The relation of the protozoan flagellate, 
Retortamonas gryllotalpae, etc. Tr. Am. Micr. Soc, 51:225. 

Wenyon, C. M.: (1911) Oriental sore in Bagdad, etc. Parasitology, 

— (1926) Protozoology. London and Baltimore. 

Wolcott, G. B.: (1952) Mitosis in Trypanosoma lewisi. J. Morphol., 

Wood, Fae D.: (1934) Natural and experimental infection of 
Triatoma protracta Uhler and mammals in California with 
American human trypanosomiasis. Am. J. Trop. Med., 14:497. 

— (1936) Trypanosoma neotomae sp. nov., etc. Univ. California 
Publ. Zool., 41:133. 

and Wood, S. F.: (1941) Present knowledge of the distribu- 

tion of Trypanosoma cruzi in reservoir animals and vectors. Am. 
J. Trop. Med., 21:335. 
Yamasaki, S.: (1924) Ueber Leptomonas ctenocephali, etc. Arch. 
Protist,, 48:137. 

Chapter 15 
Order 3 Polymastigina Blochmann 

THE Zoomastigina placed in this group possess 3-8 (in one 
family up to a dozen or more) flagella and generally speaking, 
are minute forms with varied characters and structures. Many 
possess a cytostome and one to many nuclei and the body is covered 
by a thin pellicle which allows the organism to change form, although 
each species shows a typical form. The cytoplasm does not show any 
special cortical differentiation; in many, there is an axial structure 
known as axostyle or axostylar filaments (p. 70). In Trichomonadi- 
dae, there is usually a rod-like structure, known as costa (Kunstler), 
along the base of the undulating membrane and in Devescovinidae, 
there is a subtriangular body, the cresta, directly below the basal 
portion of the trailing flagellum, which in some species is very large 
and capable of movement. At the time of division, the old costa is 
retained and a new one is formed; the cresta however is resorbed 
and two new ones are produced (Kirby). Parabasal bodies of various 
form and structure occur in many species. 

The majority of Polymastigina inhabit the digestive tract of ani- 
mals and nutrition is holozoic or saprozoic (parasitic). Many xylopha- 
gous forms hold symbiotic relationship with the host termites. 
Asexual reproduction is binary or multiple fission. Encystment is 
common. Sexual reproduction has been recognized in a few species. 
Taxonomy of species living in termites (Kirby, 1926). 

With 1 nucleus Suborder 1 Monomonadina 

With 2 nuclei Suborder 2 Diplomonadina (p. 392) 

With more than 2 nuclei Suborder 3 Polymonadina (p. 396) 

Suborder I Monomonadina 

Without axial organella 

With 3 flagella Family 1 Trimastigidae (p. 370) 

With 4 flagella 

None undulates on body surface 

Without cell-organ of attachment. . Family 2 Tetramitidae (p. 371) 

With rostellum Family 3 Streblomastigidae (p. 374) 

One undulates on body surface . . Family 4 Chilomastigidae (p. 374) 

With more than 4 flagella Family 5 Callimastigidae (p. 375) 

With axial organella 

Without undulating membrane 
Without cresta 

Flagella not adhering to body 

Without rostellum Family 6 Polymastigidae (p. 376) 

With rostellum Family 7 Oxymonadidae (p. 378) 




Flagellar cords on body surface 

Family S Dinenymphidae (p. 379) 

With cresta Family 9 Devescovinidae (p. 380) 

With undulating membrane. . . .Family 10 Trichomonadidae (p. 385) 

Family 1 Trimastigidae Kent 

Genus Trimastix Kent. Ovate or pyriform; naked; free-swimming; 
with a laterally produced membranous border; 3 flagella (1 anterior 
flagellum vibrating, 2 trailing); salt water. Species (Grasse, 1952a). 

T. marina K. (Fig. 154, a). About 18ju long; salt water. 

Fig. 154. a, Trimastix marina, X1250 (Kent); b, Dallingeria drysdali, 
X2000 (Kent); c, Macromaslix lapsa, X1500 (Stokes). 

T. convexa Grasse (Coelotrichomastix convexa Hollande) (Fig. 167, 
a). In life 10-22/* by 8-10/x; dorsal side strongly convex, ventral side 
concave; three free flagella nearly equally long, fourth flagellum 
borders the undulating membrane, present on the concave side and 
becomes free beyond the posterior end of body; spherical nucleus 
voluminous, with a large endosome; free-living and coprozoic (Hol- 
lande, 1939; Grasse, 1952a). 

Genus Dallingeria Kent. Free-Swimming or attached; with trail- 
ing flagella; body small; with drawn-out anterior end; fresh water 
with decomposed organic matter. 

D. drysdali K. (Fig. 154, b). Small; elongate oval; less than 6^ 
long ; stagnant water. 

Genus Macromastix Stokes. Free-swimming, somewhat like 


Dallingeria, but anterior region not constricted; 3 flagella from an- 
terior end; one contractile vacuole; fresh water. 

M. lapsa S. (Fig. 154, c). Ovoid; 5.5/x long; anterior flagellum 1/2 
and trailing flagella 2-3 times body length; pond water. 

Genus Mixotricha Sutherland. Large; elongate; anterior tip 
spirally twisted and motile; body surface with a coat of flagella in 
closely packed transverse bands (insertion and movement entirely 
different from those of Trichonympha) except posterior end ; 3 short 
flagella at anterior end; nucleus, 20m by 2ju, connected with blepharo- 
plasts by prolonged tube which encloses nucleus itself; cytoplasm 
with scattered wood chips; in termite gut. One species. Taxonomic 
position undetermined. 

M. paradoxa S. About 340^ long, 200> broad and 25/x thick ; in gut 
of Mastotermes darwiniensis ; Australia (Sutherland). 

Family 2 Tetramitidae Butschli 

Genus Tetramitus Perty. Ellipsoidal or pyriform; free-swimming; 
cytostome at anterior end; 4 flagella unequal in length; a contractile 
vacuole; holozoic; fresh or salt water or parasitic. Species (Klug, 

T. rostratus P. (Fig. 15G, a). Body form variable, usually ovoid and 
narrowed posteriorly: 18-30ju by 8-11 n; stagnant water. Bunting 
(1922, 1926) observed an interesting life cycle of what appeared to be 
this organism which she had found in cultures of the caecal content 
of rats (Fig. 155). Nuclear division (Bunting and Wenrich, 1929). 

T. pyriformis Klebs (Fig. 156, b). Pyriform, with pointed poste- 
rior end; 11-13/x by 10-1 2/x; stagnant water. 

T. salinus (Entz) (Fig. 156, c). 2 anterior flagella, 2 long trailing 
flagella; nucleus anterior; cytostome anterior to nucleus; a groove to 
posterior end; cytopharynx temporary and length variable; 20-30^ 
long (Entz); 15-19ju long (Kirby). Kirby observed it in a pool with 
a high salinity at Marina, California. 

Genus Collodictyon Carter. Body highly plastic; with longitudinal 
furrows; posterior end bluntly narrowed or lobed; no apparent 
cytostome; 4 flagella; a contractile vacuole anterior; fresh water. 

C. triciliatum C. (Fig. 156, d). Spherical, ovoid or heart-shaped; 
27-60/x long; flagella as long as the body; pond water. Cytology 
(Rhodes, 1919); food ingestion (Belaf, 1921). 

Genus Costia Leclerque. Ovoid in front view, pyriform in profile; 
toward the right side, there is a shallow depression which leads into 
cytostome (?) and from which extend two long and two short flagella 
(only two flagella (Andai, 1933)); contractile vacuole posterior; en- 
cystment ; ectoparasitic in freshwater fishes. 



Fig. 155. Diagram illustrating the life-cycle of Tetramitus rostratus 
(Bunting), a, cyst; b, vegetative amoeba; c, division; d, after division; 
e, f, stages in transformation to flagellate form; g, fully formed flagel- 
late; h, flagellate prior to division; i, flagellate after division; j-1, trans- 
formation stages to amoeba. 

C. necatrix (Henneguy) (Fig. 156, e-j). 10-20ju by 5-10/x (Henne- 
guy), 5-18/x by 2.5-7 fj. (Tavolga and Nigrelli, 1947) ; nucleus central; 
uninucleate cyst, spherical, 7-10/iin diameter; when present in large 
numbers, the epidermis of the fish appears to be covered by a whitish 
coat. Davis (1943) found a similar organism which measured 9-14^ 
by 5-8 m, on trout, Salmo irideus and Salvelinus fontinalis, and 
named it Costia pyriformis. 

Genus Enteromonas da Fonseca (Tricercomonas Wenyon and 
O'Connor). Spherical or pyriform, though plastic; 3 anterior flagella; 
the fourth flagellum runs along the flattened body surface and ex- 
tends a little freely at the posterior tip of body; nucleus anterior; 
no cytostome; cyst ovoid and with 4 nuclei when mature; parasitic 



in mammals, da Fonseca (1915) originally observed only 3 flagella 
and no cysts; 4 flagella and encysted forms were noticed in Tri- 
cercomonas by Wenyon and O'Connor (1917); in da Fonseca's ori- 
ginal preparations, Dobell (1935) observed 4 flagella as well as cysts 
and concluded that Enteromonas and Tricercomonas are one and 
the same flagellate. 

Fig. 156. a, Tetramitus rostratus, X620 (Lemmermann); b, T. pyri- 
formis, X670 (Klebs); c. T. salinus, X1630 (Kirby); d, Collodictyon 
triciliatum, X400 (Carter); e-j, Costia necatrix (e, f, XSOO (Weltner); 
g-i, X1400 (Moroff); j, two individuals attached to host integument 
X500 (Kudo)); k, Enteromonas hominis, X1730 (Wenyon and O'Con- 
nor); 1, Copromastix prowazeki, X1070 (Aragao). 

E. hominis da F. (T. intestinalis W. and O) (Figs. 156, k; 157, ad). 
Trophozoites 4-l(hz by 3-6ju; nucleus circular or pyriform, with a 
large endosome, near anterior end; 4 flagella take their origins in 
blepharoplasts located close to nucleus; cytoplasm vacuolated or 
reticulated, contains bacteria; cysts ovoid, 6-8/x by 4-6/z; with 1, 2, 
or 4 nuclei; commensal in the lumen of human intestine; found in 
diarrhoeic stools. Widely distributed. 

E. caviae Lynch. Similar to the species mentioned above, but 
slightly smaller; in the caecum of guinea-pigs (Lynch, 1922). Cytol- 
ogy (Nie, 1950). 


Genus Copromastix Aragao. Four anterior flagella equally long; 
body triangular or pyramidal; coprozoic. 

C. prowazeki A. (Fig. 156, I). About 16-18/* long; in human and 
rat faeces. 

Genus Karotomorpha Travis (Tetramastix Alexeieff). Elongate 
pyriform; body more or less rigid; four unequal flagella at the an- 
terior end, in two groups; nucleus anterior; without cytostome; 
parasitic in the intestine of Amphibia. Species (Travis, 1934). 

K. bufonis (Dobell) (Fig. 157, e). Spindle in shape; 12-16/x by 
2-6/*; in the intestine of frogs and toads. Cytology (Grasse, 1926). 

Family 3 Streblomastigidae Kofoid and Swezy 

Genus Streblomastix K. and S. Spindle-form; with a rostellum, 
the anterior tip of which is enlarged into a sucker-like cup; below the 
cup are inserted 4 (Kidder) or 6 (Kofoid and Swezy) equally long 
flagella; extremely elongate nucleus below rostellum; body surface 
with 4 or more spiral ridges; in termite gut. One species. 

S. strix K. and S. (Fig. 157, /, g). 15-52/* by 2-15/*; 4-8 spiral 
ridges; blepharoplast in rostellum; in Termopsis angasticollis. 

Family 4 Chilomastigidae Wenyon 

Four flagella, one of which undulates in the cytostome. 

Genus Chilomastix Alexeieff. Pyriform; with a large cytostomal 
cleft at anterior end; nucleus anterior; 3 anteriorly directed flagella; 
short fourth flagellum undulates within the cleft; cysts common; in 
intestine of vertebrates. Several species. 

C. mesnili (Wenyon) (Fig. 157, h-k). The trophozoite is oval or 
pyriform; 5-20 (10-15)/* long; jerky movements; a large cytosto- 
mal cleft near anterior end; nucleus, vesicular, often without endo- 
some; 3 anterior flagella about 7-10/z long; the fourth flagellum 
short, undulates in the cleft which ridge is marked by 2 fibrils. The 
cyst pyriform; 7-10/* long; a single nucleus; 2 cytostomal fibrils and 
a short flagellum; commensal in the caecum and colon (some con- 
sider also in small intestine) of man. Both trophozoites and cysts oc- 
cur in diarrhoeic faeces. It is widely distributed and very common. 
Cytology (Kofoid and Swezy, 1920); cultivation (Boeck, 1921). 

C. intestinalis Kuczynski. In guinea-pigs; 13-27/* by 5—1 1/x (Gei- 
man, 1935); 8.8-28/* by 6.6-11/* (Nie, 1950). 

C. bettencourti da Fonseca. In rats and mice. 

C. cuniculi da F. In rabbits. 

C. caprae d. F. In goat. 



Fig. 157. a-d, Enteromonas hominis, XI 730 (Wenyon and O'Connor) 
(a, b, living and c, stained trophozoites; d, a stained cyst); e, Karoto- 
morpha bufonis, X2000 (Grass6); f, Streblomastix strix, X1030; g, ante- 
rior end of the organism, showing the rostellum, blepharoplast, sucking 
cup and flagella (Kidder); h-k, Chilomastix mesnili, X1530 (h, living and 
i, stained trophozoites; j, a fresh cyst; k, a stained cyst); 1, a stained 
trophozoite, and m, a stained cyst of C. gallinarum, X1330 (Boeck and 
Tanabe); n, Callimastix frontalis, XI 500 (Braune); o, C. equi, XI 100 

C. gallinarum Martin and Robertson (Fig. 157, I, m). 11-20/x by 
5-6^; in the caeca of turkeys and chicks. Morphology (Boeck and 
Tanabe, 1926). 

Family 5 Callimastigidae da Fonseca 

Flagella 12 or more; in stomach of ruminants or in caecum and 
colon of horse. 

Genus Callimastix Weissenberg. Ovoid; compact nucleus central 
or anterior; 12-15 long flagella near anterior end, vibrate in unison. 
Weissenberg (1912) considered this genus to be related to Lopho- 
monas (p. 407), but organism lacks axial organellae;in Cyclops and 
alimentary canal of ruminants and horse. 

C. cyclopis W. In body-cavity of Cyclops sp. 

C. frontalis Braune (Fig. 157, n). 12 flagella; about 12ju long; fla- 
gella 30ju long; in cattle, sheep and goats. 



C. equi Hsiung (Fig. 157, o). 12-15 flagella; 12-18/* by 7-10/*; 
nucleus central; in caecum and colon of horse. 

Family 6 Polymastigidae Biitschli 

Genus Polymastix Biitschli. Pyriform; four flagella arise from two 
blepharoplasts located at anterior end; cytostome and axostyle in- 
conspicuous; body often covered by a protophytan; commensals in 
insects. Species (Grasse, 1926, 1952). 

P. melolonthae (Grassi) (Fig. 158, a). 10—15/* by 4-8/*; body cov- 
ered by Fusiformis melolonthae (Grasse, 1926) : in the intestine of 
Melolontha, Oryctes, Cetonia, Rhizotrogus, Tipula, etc. 

Fig. 158. a, Polymastix melolonthae, X2000 (Grasse); b, Eutrichomastix 
serpentis, X1450 (Kofoid and Swezy); c, E. batrachorum, X1350 (Dobell); 
d, E. axostylis, X2000 (Kirby); e, Chilomitus caviae (Nie); f, Hexamastix 
termopsidis, X2670 (Kirby); g, H. batrachorum; h, Protrichomonas legeri, 
X1000 (Alexeieff); i, Monocercomonoides melolonthae, X2000 (Grasse); j, 
Cochlosoma rostraturn, X1465 (Kiiriura). 

Genus Eutrichomastix Kofoid and Swezy (Trichomastix Bloch- 
mann). Pyriform; anterior end rounded; cytostome and nucleus 
anterior; 3 flagella of equal length arise from anterior end, the fourth 
trailing; axostyle projects beyond posterior end of body; all endo- 

E. serpentis (Dobell) (Fig. 158, b). About 10-25/* long; in intestine 


of snakes: Pituophis, Eutaenia, and Python (Kofoid and Swezy, 

E. balrachorum (Dobell) (Fig. 158, c). Ovoid; 6-20/x long; in 
intestine of Ranafusca (Dobell, 1909). 

E. axostylis Kirby (Fig. 158, d). Elongate, ellipsoid, or pyriform; 
axostyle projecting; 5-10.5/xby 2-3.5/*; 3 anterior flagella 5-1 0/x long; 
in gut of Nasutitermes kirbyi (Kirby, 1931). 

Genus Chilomitus da Fonseca. Elongate oval; pellicle well de- 
veloped; aboral surface convex; cytostome near anterior end, 
through which four flagella originating in a bi-lobed blepharoplast, 
protrude; rudimentary axostyle; nucleus and parabasal body below 
the cytostome (da Fonseca, 1915). 

C. caviae da F. (Fig. 158, e). In the caecum of guinea-pigs; stained 
trophozoites 6-14/i by 3.1-4.6/x; cytoplasm contains siderophilic 
bodies of unknown nature (Nie, 1950). 

Genus Hexamastix Alexeieff. Body similar to Eatrichomastix, 
but with 6 flagella, of which one trails; axostyle conspicuous; para- 
basal body prominent. 

H. termopsidis Kirby (Fig. 158, /). Ovoidal or pyriform; 5-1 1m 
long; flagella 15-25^ long; in gut of Zootermopsis angusticollis and 
Z. nevadensis; California (Kirby, 1930). 

H. caviae and H. robustus were described by Nie (1950) from the 
caecum of guinea-pigs. 

H. balrachorum Alexeieff (Fig. 158, g). Oval or spindle form; 8-14ju 
by 4-8ju; flagella about body length; in gut of Triton taeniatus. 

Genus Protrichomonas Alexeieff. 3 anterior flagella of equal 
length, arising from a blepharoplast located at anterior end; para- 

P. legeri A. (Fig. 158, h). In oesophagus of the marine fish, Box 

Genus Monocercomonoides Travis (Monocercomonas Grassi). 
Small; 4 flagella inserted in pairs in two places; two directed an- 
teriorly and the other two posteriorly; axostyle filamentous; para- 
sitic. Taxonomy (Travis, 1932). 

M. melolonthae (Grassi) (Fig. 158, ?'). Ovoid: 4-1 5/x long; in the 
larvae of Melolontha melolontha, etc. 

Genus Cochlosoma Kotlan. Body small, oval; sucker in the an- 
terior half; 6 flagella; axostyle filamentous; parasitic (Kotlan, 1923). 

C. rostratum Kimura (Fig. 158, j). In the colon of domestic ducks, 
Anas platyrhynchus and Carina moschata; 6-10m by 4-6. 5^ (Kimura, 
1934). McNeil and Hinshaw (1942) observed this organism in the 
intestine of young poults and in the region of caecal tonsil in adults. 



Family 7 Oxymonadidae Kirby 

Genus Oxymonas Janicki. Attached phase with a conspicuous 
rostellum, the anterior end of which forms a sucking-cup for attach- 
ment; pyriform. In motile phase, rostellum is less conspicuous; 2 
blepharoplasts located near the anterior extremity of axostyle, give 
rise to 2 flagella each; axostyle conspicuous; xylophagous; in termite 
and woodroach; sexual reproduction in some (Cleveland, 1950). 

Fig. 159. a, b, Oxymonas dimorpha (Connell) (a, a motile form, X900; 
b, an attached aflagellate form, X460); c, 0. grandis, X265 (Cleveland); 
d, Proboscidiella kofoidi, X600 (Kirby). 

0. dimorpha Connell (Fig. 159, a, b). Subovoid; delicate pellicle; 
axostyle slightly protruding; a pair of long anterior flagella from 
2 blepharoplasts, connected by rhizoplast; nucleus anterior. When 
attached to intestine, rostellum elongate, flagella disappear; 17m by 
14/z to 195/x by 165m; in Neotermes simplicicornis; California and 
Arizona (Connell, 1930). 

0. grandis Cleveland (Fig. 159, c). Body 76m by 31m to 183m by 
79m; rostellum varies 30-200m in length; nucleus without an endo- 


some, anterior, about 20-23/x in diameter; axostyle consists of a 
staining part and a non-staining part; in the intestine of Neotermes 
dalbergiae and N. tectonae (Cleveland, 1935). 

Genus Proboscidiella Kofoid and Swezy (Microrhopalodina Grassi 
and Foa; Kirbyella Zeliff). Attached and motile forms similar to Oxy- 
monas; but multinucleate; 4 flagella from each karyomastigont (p. 
315); rostellum with filaments which extend posteriorly as axo- 
styles; in termite gut (Kofoid and Swezy, 1926; Zeliff, 1930a). 

P. kofoidi Kirby (Fig. 159, d). Average size 66m by 46m; rostellum 
as long as, or longer than, the body; karyomastigonts 2-19 or more 
(average 8) ; each mastigont with 2 blepharoplasts from which extend 
4 flagella; in Cryptolermes dudleyi (Kirby, 1928). 

Family 8 Dinenymphidae Grassi and Foa 

Genus Dinenympha Leidy. Medium large; spindle form; 4-8 
flagellar cords adhering to body which are spirally twisted about one 
turn; the flagella free at the posterior end; axostyle varies from cord 
to band; pyriform nucleus, anterior, with a large endosome; in ter- 
mite gut. Species (Koidzumi, 1921). 

D. gracilis L. (Fig. 160, a). 24-50/1 by 6-1 2m ; body flattened and 
twisted; ends attenuated; with adhering protophytes; in Reticuli- 
termes flavipes. 

D. fimbriata Kirby (Fig. 140, b). 52-64m by 8-18/x; 4-8 flagellar 
cords; with adherent protophytes; axostyle varies in width; in hesperus (Kirby, 1924). 

Genus Pyrsonympha Leidy. Large; club-shaped, the posterior end 
is rounded; body surface with 4-8 flagellar cords which are arranged 
lengthwise or slightly spirally; flagella extend freely posteriorly; 
blepharoplast at the anterior tip, often with a short process for at- 
tachment; axostyle a narrow band, may be divided into parts; large 
pyriform nucleus anterior; in termite gut. Species (Koidzumi, 1921) ; 
nuclear division (Cleveland, 1938). 

P. vertens L. (Fig. 160, c). About 100-150m long; 4-8 flagellar 
cords; in Reticulitermes flavipes. Cytology (Duboscq and Grasse, 

P. granulata Powell (Fig. 160, d). 40-120m by 5-35m; 4-8 flagellar 
cords; in Reticulitermes hesperus (Powell, 1928). 

Genus Saccinobaculus Cleveland. Elongate to spherical; 4, 8, or 
12 flagella adhere to the body, and project out freely; axostyle is an 
extremely large paddle-like body and undulates, serving as cell- 
organ of locomotion; posterior end of axostyle enclosed in a sheath; 
in woodroach gut. 



S. ambloaxostylus C. (Fig. 160, e-g). 65-1 10/x by 18-26/*; in 
Cryptocercus punctulatus. Sexual reproduction (Cleveland, 1950a). 

Genus Notila Cleveland. Body elongate, plastic; four flagella, the 
attached portion of which shows attached granules (Fig. 160, i); 
axostyle large, paddle-like, much broader than that of Pyrsonympha ; 

Fig. 160. a, Dinenympha gracilis, X730;b, D. fimbriate/,, X625 (Kirby); 
c, Pyrsonympha vertens, X730; d, P. granulata, X500 (Powell); e-g, 
Saccinobaculus ambloaxostylus (Cleveland) (e, whole organism, X600; 
f, anterior and g, posterior portion of vegetative individual); h-j, Notila 
proteus (Cleveland) (h, diploid individual, X360; i, anterior and j, pos- 
terior ends of the organism). 

no axostyler sheath at posterior end, but with large granules or 
spherules embedded in it; in Cryptocercus punctulatus. 

N. proteus C. (Fig. 160, h-j). Size not given; gametogenesis and 
sexual fusion, induced by the molting hormone of the host; diploid 
number of chromosomes 28 (Cleveland, 19501)). 

Family 9 Devescovinidae Doflein 

Usually 3 anterior flagella and a trailing stout flagellum; near 
base of trailing flagellum an elongated cresta (becoming a large 



internal membrane in some species) (Fig. 161); trailing flagellum 
lightly adheres to body surface along edge of cresta; axostyle; para- 
basal body of various forms; single nucleus anterior; without undu- 
lating membrane; generally xylophagous. Cytology and morpho- 
genesis (Kirby, 1944). 

ant. flagella 
ant. lamella 
bleph. group 
nucl. rhiz. 
parab. fil. 
parab. body 


chrom. mass 
nucl. memb. 
chr. cone in ax. 

parab. spiral 

chromoph. element 
of pb. 

tr. flagellum 

Fig. 161. A diagrammatic view of the anterior part of Devescovina lem- 
niscata, showing the cresta and other organellae (Kirby). 

Genus Devescovina Foa. Elongate body, usually pointed poste- 
riorly; 3 anterior flagella about the body length; trailing flagellum, 
slender to band-form, about 1-1.5 times the body length; cresta; 
parabasal body spiraled around axostyle or nucleus; in termite in- 
testine. Many species (Kirby, 1941, 1949). 

D. lemniscata Kirby (Figs. 161; 162, a). 21-51/* by 9-17//; trailing 
flagellum a band; cresta long, 7-9/*; in Cryptotermes hermsi and many 
species of the genus; species of Neotermes, Glyptotermes and 
Kalotermes (Kirby, 1926a). 

Genus Parajoenia Janicki. Medium large; with rounded extremi- 
ties; 3 anterior flagella and trailing flagellum long; cresta of moder- 
ate size; parabasal body well developed with its anterior end close to 
blepharoplast; stout axostyle expanded anteriorly into leaf -like 
capitulum, bearing a longitudinal keel; in intestine of termites. 

P. grassii J. (Fig. 162, b). 29-59/* by 12-33/*; trailing flagellum 



Fig. 162. a, Devescovina lemniscata, X1600; b, Parajoenia grassii, with 
attached spirochaetes, XH50; c, Foaina nana, XH50; d, Macrotricho- 
monas pulchra, X1600 (all after Kirby); e, Metadevescovina debilis, X1130 
(Light, modified). 


stout, cordlike; cresta about 9/t long; in Neotermes connexus (Kirby, 
1937, 1942a). 

Genus Foaina Janicki {Janickiella Duboscq and Grasse; Para- 
devescovina, Crucinympha Kirby). Small to medium large; 3 anterior 
flagella; trailing flagellum about twice the body length; cresta 
slender, 2.5-17/x long; parabasal body single, in some with rami; in 
intestine of termites. Many species (Kirby, 1942a, 1949). 

F. nana Kirby (Fig. 162, c). 6-18/x by 4.5-8.5/x; trailing flagellum 
a moderately stout cord, 2-3 times the body length; cresta slender, 
8.5m long; filament part of the parabasal body reaching the middle 
of body; in Cryptotermes hermsi and many species of the genus; also 
species of Glyptotermes, Rugitermes, and Procryptotermes (Kirby, 

Genus Macrotrichomonas Grassi. Large; 3 anterior flagella; trail- 
ing flagellum well developed, 1-1.5 times the body length; cresta a 
broad internal membrane, 21-86/i long; parabasal body coiled around 
the axostyle, 1-13 times; in termite gut. Several species (Kirby, 
1942, 1949). 

M. pulchra G. (Fig. 162, d). 44-91/x by 21-41/*; trailing flagellum 
band-form; cresta large; parabasal body coiled closely 4-10 times; 
in Glyptotermes parvulus, and many other species of the genus (Kirby, 

Genus Metadevescovina Light. Moderately large; 3 anterior 
flagella; a short trailing flagellum; cresta small; parabasal body 
loosely coiled around axostyle; anterior end of axostyle in a loop; 
in termite gut. Many species (Light, 1926; Kirby, 1945). 

M . debilis L. (Fig. 162, e). 30-70/* by 15-30/*; in Kalotermes hub- 

Genus Caduceia Franca. Large; 3 long anterior flagella; trailing 
flagellum slender, shorter than body; cresta relatively small, 1— 12/z 
long; parabasal body coiled around axcstyle 2-20 times; nucleus 
relatively large; axostyle terminates in filament; in termites. Several 
species (Kirby, 1942, 1949). 

C. bugnioni Kirby (Fig. 163, a). 48-80/* by 18-40/*; in Neotermes 
greeni (Kirby, 1942). 

Genus Hyperdevescovina Kirby. Similar to Caduceia; but cresta 
very small ;stout axostyle projects from the body ; in Proglyptotermes, 
Neotermes; New Zealand and South Africa. Many species (Kirby, 

H. calotermitis (Nurse). 52-1 14/* by 30-65//; projecting portion of 
the axostyle 45-63/*; in Proglyptotermes browni; New Zealand. 

Genus Pseudodevescovina Sutherland. Large; 3 short anterior 



fiagella; one short trailing flagellum; axostyle stout; cresta of moder- 
ate size; parabasal body large, divided into a number of attached 
cords; in termite gut. Several species (Kirby, 1945). 

P. uniflagellate, S. (Fig. 163, b). 52-95m by 26-60/z; 3 delicate 
fiagella, 30/z long; trailing flagellum a little stouter; cresta 11-20/* 
long; main parabasal body C-shaped, with 7-19 attached cords; in 
Kalotermcs insularis (Kirby, 1936, 1945). 

Fig. 163. a, Caduceia bugnioni, X930; b, Pseudodevescovina unifiagel- 
lata, X1190; c, Bullanympha silvestrii, X780 (all after Kirby); d, e, 
Gigantomonas herculea (Dogiel) (d, X530; e, amoeboid phase (Myxo- 
monas), X400). 


Genus Bullanympha Kirby. Flagella and cresta similar to those in 
Pseudodevescovina; axostyle similar to that in Caduceia; proximal 
part of parabasal body bent in U-form around the nucleus and at- 
tached voluminous distal portion coiled around the axostyle; in 
termite gut (Kirby, 1938, 1949). 

B. silvestrii K. (Fig. 163, c). 50-138/* by 35-100/*; cresta about 5.8m 
long; distal portion of parabasal body coils around axostyle about 
twice; in Neotermes erythraeus. 

Genus Gigantomonas Dogiel (Myxomoiias D.). Medium large; 3 
anterior flagella; a long and stout trailing flagellum; cresta conspicu- 
ously large; large axostyle; in termite gut. According to Kirby (1946), 
the so-called undulating membrane is a large cresta; in aflagellate 
phase (Myxomonas) the nuclear division takes place. 

G. herculea D. (M. polymorpha D.) (Fig. 163, d, e). 60-75/* by 
30-35/z; in the intestine of Hodotermes mossambicus (Kirby, 1946). 

Family 10 Trichomonadidae Wenyon 

Kirby (1947) considers that Trichomonas and allied genera should 
be grouped in a new order Trichomonadina. He proposes four fami- 
lies: Monocercomonadidae, Devescovinidae, Calonymphidae and 
Trichomonadidae to be placed under it. Morphology and taxonomy 
(Grasse, 1952a}. 

Genus Trichomonas Donne. Pyriform ; typically with four free an- 
terior flagella; fifth flagellum along the outer margin of the undulat- 
ing membrane; costa at the base of the membrane; axostyle de- 
veloped, often protruding beyond the posterior end of the body; en- 
cystment has not been definitely observed; all parasitic. Numerous 
species (Wenrich, 1944). Cytology and morphogenesis (Kirby, 1944) ; 
division process (Kuczynski, 1918). 

T. hominis (Davaine) (Fig. 164, a). Active flagellate, undergoing a 
jerky or spinning movement; highly plastic, but usually ovoid or 
pyriform; 5-20/t long; cytostome near anterior end; 4 anterior 
flagella equally lpng; fifth flagellum borders undulating membrane 
which is seen in life ; in degenerating individuals the membrane may 
undulate, even after loss of flagella, simulating amoeboid movement; 
axostyle straight along the median line; vacuolated cytoplasm with 
bacteria; commensal in the colon and ileum of man; found in diarr- 
hoeic stools. Wenrich (1944) states that in all 20 cases which he 
studied, some or most of the individuals showed five anterior flagella 
and two unequal blepharoplasts. 

Since encysted forms have not yet been found, transmission is as- 
sumed to be carried on by trophozoites. According to Dobell (1934), 



he became infected by an intestinal Trichomonas of a monkey 
(Macacas nemestrinus) by swallowing "a rich two-day culture" plus 
bacteria which were mixed with 10 cc. of sterilized milk on an empty 
stomach. The presence of Trichomonas in his stools was established 
on the 6th day by culture and on the 13th day by microscopical 
examination after taking in the cultures. The infection which lasted 
for about four and a half years, did not cause any ill effects upon 

Fig. 164. Diagrams showing the species of Trichomonas which live 
in man, X2500 (modified after Wenrich). a, Trichomonas hominis; b, T. 
tenax; c. T. vaginalis. 

him. The organism is killed after five minutes' exposure to N/20 
HC1 at 37°C, but at 15-22°C, is able to survive, though in small 
numbers, up to 15 minutes after exposure to the acid (Bishop, 1930). 
This flagellate is widely distributed and of common occurrence, es- 
pecially in tropical and subtropical regions. 

T. tenax (Miiller) (T. elongata Steinberg; T. buccalis Goodey) 
(Fig. 164, b). Similar to the last mentioned species; commensal in the 
tartar and gum of human mouth. Nomenclature (Dobell, 1939). 

T. vaginalis Donne (Fig. 164, c). Broadly pyriform; 10-30/x by 
10-20/x; cytoplasm contains many granules and bacteria; cytostome 
inconspicuous; nutrition parasitic and holozoic; parasitic in human 
reproductive organ. Although the organism does not enter the vagi- 
nal tissues, many observers believe it to be responsible for certain 
diseases of the vagina. Trussell and Johnson (1945) maintain that it 



is capable of inciting an inflammatory reaction in the vaginal mucous 
membrane and according to Hogue (1943), this flagellate produces a 
substance which injures the cells in tissue culture. It occurs also in 
the male urethra (Feo, 1944). Morphology (Reuling, 1921; Wenrich, 
1939, 1944, 1944a, 1947); taxonomy, structure and division (Hawes, 
1947); comprehensive monograph (Trussell, 1947). 
Because of the morphological similarity of these three species of 

Fig. 165. a, Trichomonas microti, X2000 (Wenrich and Saxe); b-d, 
T. gallinae, X1765 (Stabler) (b, from domestic pigeon; c, from turkey; 
d, from red- tailed hawk); e, T. linearis, X2000 (Kirby). 

human Trichomonas, a number of workers maintain that they may 
be one and the same species. Dobell (1934) inoculated a rich culture 
of Trichomonas obtained from his stools into the vagina of a monkey 
(Macacus rhesus) and obtained a positive infection which was easily 
proven by culture, but unsatisfactorily by microscopical examina- 
tion of smears. The infection thus produced lasted over three years 
and did not bring about any ill effect on the monkey. He considers 
that T. vaginalis and T. hominis are synonyms and that there occur 
diverse strains different in minor morphological characters and phys- 
iological properties. Andrews (1929) noted the organism obtained 
from vaginal secretion was larger than T. hominis and its undulating 
membrane extended for 1/2 or 2/3 the body length, but when cul- 
tured in vitro, the organisms became smaller in size and the undu- 
lating membrane protruded beyond the body as a free flagellum. On 
the other hand, Stabler and his co-workers (1941, 1942) failed to ob- 
tain infections in volunteers by inoculating intravaginally with cul- 


tures of T. hominis. Wenrich (1944) who made comparative studies 
of human Trichomonas, considers that there exist distinctly recog- 
nizable morphological differences among the three human species of 
Trichomonas, as shown in Fig. 164. 

T. macacovaginae Hegner and Ratcliffe. In the vagina of Macacus 
rhesus. Dobell (1934) held that this is identical with T. vaginalis and 
T. hominis. 

T. microti Wenrich and Saxe (Fig. 165, a). In the caecum of ro- 
dents, Microtus pennsylvanicus, Peromyscus leucopus, Rattus nor- 
vegicus, Mesocricetus auratus; 4-9 m long; four free flagella; a blepha- 
roplast; undulating membrane medium long; axostyle conspicuous. 

T. gallinae (Rivolta) (T. columbae Rivolta and Delprato) (Fig. 
165, b-d). Pyriform; 6— 19>u by 2-9m; ovoid nucleus anterior together 
with a blepharoplast and parabasal body ; axostyle protrudes a little ; 
cytoplasmic granules; four anterior flagella 8-13/x long; autotomy; 
in the upper digestive tract of pigeon and also turkey, chicken, and 
dove. Experimentally it is transferable to quail, bob-white, hawk, 
canary, etc., and often fatal to hosts. Species (Travis, 1932a). Mor- 
phology (Stabler, 1941); pathology (Levine and Brandly, 1940); 
transmission (Levine et al., 1941); distribution (Barnes, 1951; Sta- 
bler, 1951). 

T. linearis Kirby (Fig. 165, e). Elongate spindle in form; 9-24^ by 
3-8 n; in the intestine of Orlhognathotermes wheeleri; Panama. Other 
species in termites (Kirby, 1931). 

T. limacis (Dujardin). In the intestine and liver-tubules of slugs, 
Deroceras agreste (Dujardin, 1841) and Limax flavus (Kozloff, 1945); 
subspherical to ellipsoidal; 11-17/x by 8-13m; four anterior flagella; 
undulating membrane extends to posterior end, with free flagellum 

Genus Tritrichomonas Kofoid. Similar to Trichomonas in appear- 
ance, behavior and structure, but with only three anterior flagella; 
parasitic. Many species. 

T. foetus (Riedmuller) (Fig. 166, a, b). In the genitalia of cattle; 
pathogenic; 10-15/z long; transmission by sexual act, from cow to 
bull or bull to cow and also by "natural contamination" (Andrews 
and Miller, 1936) from cow to cow. Infection brings about perma- 
nent or temporary suspension of the conception or the death of 
foetus. Sheep is susceptible (Andrews and Rees, 1936). Morphology 
(Wenrich and Emmerson, 1933; Morgan and Noland, 1943; Kirby, 
1951); effect on tissue culture (Hogue, 1938); effect on reproducti- 
bility of cow (Bartlett, 1947, 1948). 

T. fecalis Cleveland. 5m by 4ju to 12/x by 6m; average dimensions 



8.5/i by 5.7^; axostyle long, protruding 1/3-1/2 the body length 
from the posterior end; of 3 flagella, one is longer and less active 
than the other two; in the faeces of man. Its remarkable adapta- 
bility observed by Cleveland was noted elsewhere (p. 34). 

Fig. 166. a, Tritrichomonas foetus in life, X1330 (Morgan and Noland); 
h, a stained T. foetus, X1765 (Wenrich and Emmerson); c, d, T. muris, 
X2000 (Wenrich); e, T. batrachorum, X1465 (Bishop); f, g, T. augusta, 
X 1455 (Samuels) ; h, T. brevicollis, X2000 (Kirby) ; i, j, Pseudotrichomonas 
keilini, X2200 (Bishop). 

T. muris (Grassi) (Fig. 166, c, d). Fusiform; 10-16/* by 5-10/*; 3 
anterior flagella short, posterior flagellum extends beyond body; 
axostyle large, its tip protruding; in the caecum and colon of mice 
(Mus, Peromyscus) (Wenrich, 1921) and ground squirrel (Citellus 
lateralis chrysodeirus) (Kirby and Honigberg, 1949). The organism 


has been found within nematodes which coinhabit the host intestine. 
For example, Theiler and Farber (1932) found the flagellate in the 
chyle-stomach of Aspicularis tetraptera and Syphacia obvelata, and 
Becker (1933) noted two active individuals of this flagellate within 
the egg shell of the last-named nematode. Morphology and division 
(Kofoid and Swezy, 1915; Wenrich, 1921). 

T. caviae (Davaine). Ovoid or pyriform; 5-22/z long; undulating 
membrane long; axostyle protrudes; spherical cysts about 7 m in di- 
ameter (Galli-Valerio, 1903; Wenyon, 1926). Cytology and reproduc- 
tion (Grasse and Faure, 1939). 

T. batrachorum (Perty) (Fig. 166, e). Ovoid; 14-18/* by 6-10/x 
(Alexeieff); in culture, 7-22/z by 4-7 ju (Bishop, 1931) ; axostyle with- 
out granules; in the colon of frogs and toads. Bishop (1934) suc- 
ceeded in infecting the tadpoles of Rana temporaria and Bufo vul- 
garis by feeding them on cultures free from cysts. 

T. augusta Alexeieff (Fig. 166, /, g). Elongate spindle; 15-27/x by 
5-13/z; thick axostyle protrudes, and contains dark-staining gran- 
ules; in the colon of frogs and toads. Morphology and division 
(Kofoid and Swezy, 1915; Samuels, 1941); viability (Rosenberg, 
1936); in frog liver lesions (Stabler and Pennypacker, 1939). 

T. brevicollis Kirby (Fig. 166, h). Ovoid, undulating membrane 
curved around end; 10-1 7m by 4-8m; in the intestine of Kalotermes 
brevicollis; Panama. 

Genus Pseudotrichomonas Bishop. Body form, structure and 
movement, are exactly like those of Tritrichomonas, but free-living 
in freshwater pond (Bishop, 1939). 

P. keilini B. (Fig. 166, i, j). When alive 7-11m by 3-6m; highly 
plastic; young cultures contain more globular forms, while old cul- 
tures more elongated organisms; three unequally long anterior flag- 
ella; undulating membrane short, does not extend more than 1/2 
the body and without a free flagellum; cytostome; holozoic, feeding 
on bacteria; nucleus anterior; axostyle filamentous, invisible in life; 
no cysts; in a pond in Lincolnshire, England. Bishop (1935) culti- 
vated this flagellate in serum-saline medium, in hay infusion and in 
pond or rain water with boiled wheat grains at 4-31°C. (Bishop, 
1936, 1939). 

Genus Tricercomitus Kirby. Small; 3 anterior flagella; a long 
trailing flagellum, adhering to body; nucleus anterior, without 
endosome; blepharoplast large, with a parabasal body and an axial 
filament; parasitic. 

T. termopsidis K. (Fig. 167, b). 4-12/x by 2-3m; anterior flagella 
6-20m long; trailing flagellum 19-65m long; in gut of Zootermopsis 



angusticollis, Z. nevadensis and Z. laticeps; California and Arizona. 
Culture and encystment (Trager, 1934). 

Genus Pentatrichomonas Mesnil. Similar to Trichomonas, but 
with 5 free anterior flagella. 

P. bengalensis Chatterjee. 9-20ju by 7-14/*; in human intestine. 
Kirby (1943, 1945a) observed that of the five flagella, four arise from 

Fig. 167. a, Trimastix convexa, X1310 (Hollande); b, Tricercomitus 
termopsidis, X665 (Kirby) ; c, Pentatrichomonoides scroa, X1500 (Kirby); 
d, Pseudotrypanosoma giganteum, X435 (Kirby). 

the end of a columnar (1-2ju long) extension, while the fifth flagellum 
is a little shorter and takes its origin about 1m behind the extension. 

Genus Pentatrichomonoides Kirby. Five anterior flagella and the 
undulating membrane; axostyle very slightly developed; fusiform 
parabasal body; nucleus separated from the anterior blepharoplast; 
in termite gut. 

P. scroa K. (Fig. 167, c). 14-45/u by 6-15/z; in Cryptotermes dudleyi 
and Lobitemies longicollis. 

Genus Pseudotrypanosoma Grassi. Large, elongate; 3 anterior 
flagella; undulating membrane; slender axostyle; band-like structure 
between nucleus and blepharoplast; parabasal body long, narrow; 
in termite gut. 

P. giganteum G. (Fig. 167, d). 55-lU/u long (Grassi); 145-205/* by 



20-40m; anterior flagella about 30m long (Kirby); in gut of Poro- 
termes adamsoni and P. grandis. 

Suborder 2 Diplomonadina 

The suborder consists of a number of binucleate flagellates pos- 
sessing bilateral symmetry. 

Family Hexamitidae Kent 
Genus Hexamita Dujardin (Octomitus Prowazek). Pyriform; 2 
nuclei near anterior end; 6 anterior and 2 posterior flagella; 2 axo- 

Fig. 168. a, Hexamita inflata, X600 (Klebs); b, c, trophozoite and cyst 
of H. intestinalis, X1600 (Alexeieff); d, H. salmonis, X2100 (Davis); e, H. 
cryptocerci, X1600 (Cleveland); f, Trepomonas agilis, X1070 (Klebs); 
g, T. rotans, X710 (Lemmermann) ; h, Gyromonas ambulans, X530 
(Seligo); i, Trigonomonas compressa, X490 (Klebs); j, Urophagus rostratus, 
X800 (Klebs). 


styles; 1-2 contractile vacuoles in free-living forms; cytostome ob- 
scure; endoplasm with refractile granules; encystment; in stagnant 
water or parasitic. 

H. inflata D. (Fig. 168, a). Broadly oval; posterior end truncate; 
13-25/* by 9-1 5/z; in stagnant water. 

H. intestinalis D. (Fig. 168, b, c). 10-16/x long; in intestine of 
frogs, also in midgut of Trutta fario and in rectum of Motella tricir- 
rata and M . mustela in European waters. Morphology (Schmidt, 

H. salmonis (Moore) (Fig. 168, d). 10-12/x by 6-8/*; in intestine 
of various species of trout and salmon; schizogony in epithelium of 
pyloric caeca and intestine; cysts; pathogenic to young host fish 
(Moore, 1922, 1923; Davis, 1925). 

H. periplanetae (Belaf). 5-8 m long; in intestine of cockroaches. 

H. cryptocerci Cleveland (Fig. 168, e). 8-13/t by 4-5. 5/z; in Crypto- 
cercus punctulatus. 

H. meleagridis McXiel, Hinshaw and Kofoid (Fig. 169, a). Body 
6-12/x by 2-5/*. It causes a severe catarrhal enteritis in young tur- 
keys. Experimentally it is transmitted to young quail, chicks, and 
duckling (McNeil, Hinshaw and Kofoid, 1941). 

H. sp. Hunninen and Wichterman (1938) (Fig. 169, b). Average 
dimensions 10/x by 5.5m; found in the reproductive organs of the 
trematode, Deropristis inflata, parasitic in the eel; heavily infected 
eggs are said not to develop. 

Genus Giardia Kunstler {Lamblia Blanchard). Pyriform to ellip- 
soid; anterior end broadly rounded, posterior end drawn out; bi- 
laterally symmetrical; dorsal side convex, ventral side concave or 
flat, with a sucking disc in anterior half; 2 nuclei; 2 axostyles; 8 
flagella in 4 pairs; cysts oval to ellipsoid; with 2 or 4 nuclei and 
fibrils; in the intestine of various vertebrates. Many species. Criteria 
for species differentiation (Simon, 1921 ; Hegner, 1922) ; cytology and 
taxonomy (Filice, 1952). 

G. intestinalis (Lambl) (G. enterica Grassi; G. lamblia Stiles (Fig. 
169, c-g). When the flagella lash actively, the organism shows a slight 
forward movement with a sidewise rocking motion. The trophozoite 
is broadly pyriform, not plastic ; 9-20/x by 5-lG>; sucking disc acts as 
attachment organella; cytoplasm hyaline; 2 needle-like axostyles; 2 
vesicular nuclei near anterior margin; 8 flagella in 4 pairs; two flag- 
ella originate near the anterior end of axostyles, cross each other and 
follow the anterolateral margin of the disc, becoming free; two 
originating in anterior part of axostyles, leave the body about 1/3 
from the posterior tip; two (ventral) which are thicker than others, 
originate in axostyles at nuclear level and remain free; two (caudal) 



flagella arise from the posterior tips of axostyles; a deeply staining 
body may be found in cytoplasm. 

The cysts are ovoid and refractile; 8-14/x by 6-lOju; cyst wall thin; 
contents do not fill the wall; 2 or 4 nuclei, axostyles, fibrils and fla- 
gella are visible in stained specimens. 

This flagellate inhabits the lumen of the duodenum and other 

Fig. 169. a, Hexamita meleagridis, X1875 (McNeal et al.)\ b, an egg 
of Deropristis inflata containing Hexamita, X770 (Hunninen and Wich- 
terman); c-g, Giardia intestinalis, X2300 (c, front and d, side view of 
living organisms; e. stained trophozoite; f, fresh and g, stained mature 
cysts) . 


parts of small intestine and colon of man. Both trophozoites and 
cysts are ordinarily found in diarrhoeic faeces. In severe cases of in- 
fection, an enormous number of the organisms attach themselves to 
the mucous membrane of the intestine which may result in abnormal 
functions of the host tissues. In some cases, the flagellate has been 
reported from the gall bladder. The stools often contain unusual 
amount of mucus. Although there is no evidence that G. intestinalis 
attacks the intestinal epithelium, experimental observations point to 
its pathogenicity (Tsuchiya and Andrews, 1930). Cytology (Kofoid 
and Swezy, 1922). 

G. duodenalis (Davaine). In the intestine of rabbits; 1 3-1 9m by 8- 
U/x (Hegner, 1922). 

G. canis Hegner. In dogs; 12-17/x by 7.6-10/z; cysts oval, 9- 13m by 
7-9m (Hegner, 1922). 

G. muris (Grassi). In rats and mice; 7-13m by 5- 10m (Simon, 1922). 

G. simoni Lavier. In the small intestine of rats; 14-19m by 7-10. 5m 
(Lavier, 1924); 11—16/* by 5-8m (Nieschulz and Krijgsman, 1925). 

G. ondatrae Travis. In the intestine of the muskrat, Ondatra 
zibethica; 13m by 7m (Travis, 1939); 10m by 5.5m (Waters et al). 

G. caviae Hegner. In the intestine of guinea-pigs; 8-14m by 5.5- 
10m (Hegner, 1923). 

Genus Trepomonas Dujardin. Free-swimming; flattened; more or 
less rounded; cytostomal grooves on posterior half, one on each side; 
8 flagella (one long and 3 short flagella on each side) arise from ante- 
rior margin of groove; near anterior margin there is a horseshoe-form 
structure, in which two nuclei are located; fresh water, parasitic, 
or coprozoic. 

T. agilis D. (Fig. 168, /). More or less ovoid; 7-30m long; 1 long 
and 3 short flagella on each side; rotation movement; stagnant 
water; also reported from intestine of amphibians. 

T. rotans Klebs (Fig. 168, g). Broadly oval; posterior half highly 
flattened; 2 long and 2 short flagella on each of 2 cytostomes; stag- 
nant water. ' 

Genus Gyromonas Seligo. Free-swimming; small; form constant, 
flattened; slightly spirally coiled; 4 flagella at anterior end; cyto- 
stome not observed; fresh water. 

G. ambulans S. (Fig. 168, h). Rounded; 8-15m long; standing 

Genus Trigonomonas Klebs. Free-swimming; pyriform, plastic; 
cytostome on either side, from anterior margin of which arise 3 
flagella; flagella 6 in all; 2 nuclei situated near anterior end; move- 
ment rotation; holozoic; fresh water. 



T. compressa K. (Fig. 168, i). 24-33/x by 10-16/*; flagella of differ- 
ent lengths; standing water (King, 1936). 

Genus Urophagus Klebs. Somewhat similar to Hexamita; but 
a single cytostome; 2 moveable posterior processes; ho lo zoic; stag- 
nant water. 

U. rostratus (Stein) (Fig. 168, j). Spindle-form; 16-25/* by 6-12/*. 

Suborder 3 Polymonadina 

The polymonads are multinucleate. Each nucleus is associated 
with a blepharoplast (from which a flagellum extends), a parabasal 

Fig. 170. a, Calonympha grassii, X900 (Janicki); b, Stephanonympha 
nelumbium, X400 (Kirby); c, Coronympha clevelandi, X1000 (Kirby); 
d, Metacoronympha senta, X485 (Kirby); e, Snyderella tabogae, X350 


body, and an axial filament. Janicki called this complex karyomasti- 
gont (Fig. 170, a) and the complex which does not contain a nucleus, 
akaryomastigont (Fig. 170, e). This group includes the forms which 
inhabit the gut of various species of termites, most probably as 

Genus Calonympha Foa. Body rounded; large; numerous long 
flagella arise from anterior region; numerous nuclei; karyomastigonts 
and akaryomastigonts; axial filaments form a bundle; in termite 
gut (Foa, 1905). 

C. grassii F. (Fig. 170, a). 69-90/x long; in Cryptotermes grassii. 

Genus Stephanonympha Janicki. Oval, but plastic; numerous 
nuclei spirally arranged in the anterior half; karyomastigonts; axial 
filaments form a bundle; in termite gut (Janicki, 1911). 

S. nelumbium Kirby (Fig. 170, b). 45)u by 27m; in Cryptotermes 

Genus Coronympha Kirby. Pyriform with 8 or 16 nuclei, arranged 
in a single circle in anterior region; 8 or 16 karyomastigonts; axo- 
styles distributed; in termite gut (Kirby, 1929, 1939). 

C. clevelandi K. (Fig. 170, c). 25-53^ by 18-46/*; in Kalotermes 

Genus Metacoronympha Kirby. Pyriform; one hundred or more 
karyomastigonts arranged in spiral rows meeting at the anterior 
end; each karyomastigont is composed of nucleus, blepharoplast, 
cresta, 3 anterior flagella, a trailing flagellum, and an axostyle; axo- 
style as in the last genus; in termite gut (Kirby, 1939). 

M. senta K. (Fig. 170, d). 22-92 M by 15-67ju; karyomastigonts 
about 66-345 (average 150) in usually 6 spiral rows; in Kalotermes 
emersoni and four other species of the genus. 

Genus Snyderella Kirby. Numerous nuclei scattered through the 
cytoplasm; akaryomastigonts close together and extend through the 
greater part of peripheral region; axial filaments in a bundle; in 
termite gut (Kirby, 1929). 

S. tabogae K. (Fig. 170, e). Pyriform; rounded posteriorly; bluntly 
conical anteriorly; 77-172ju by 53-97/*; in Cryptotermes longicollis. 


Alexeieff, A.: (1912) Sur quelques noms de genre des flagelles, etc 

Zool. Anz., 39:674. 
Andai, G.: (1933) Ueber Costia necatrix. Arch. Protist., 79:284. 
Andrews, J. and Miller, F. W.: (1936) Non-venereal transmission 

of Trichomonas foetus infection in cattle. Am. J. Hyg., 24:433. 
- (1938) Trichomonas foetus in bulls. Ibid., 28:40. 


and Rees, C. W. : (1936) Experimental Trichomonas foetus 

infection in sheep. J. Parasit., 22:108. 

Andrews, Mary N.: (1929) Observations on Trichomonas vaginalis, 
etc. J. Trop. Med. Hyg., 32:237. 

Barnes, W. B.: (1951) Trichomoniasis in mourning doves in Indi- 
ana. Indiana Audub. Quart., 29:8. 

Bartlett, D. E.: (1947) Trichomonas foetus infection and bovine re- 
production. Am. J. Vet. Res., 8:343. 

(1948) Bovine venereal trichomoniasis: etc. Proc. U. S. 

Livestock Sanit., A. 1947, p. 170. 

Becker, E. R. : (1933) Two observations on helminths. Tr. Am. 
Micr. Soc, 52:361. 

Belar, K: (1921) Protozoenstudien. III. Arch. Protist., 43:431. 

Bishop, Ann: (1930) The action of HC1 upon cultures of Tricho- 
monas. Parasitology, 22:230. 

(1931) The morphology and method of division of Tricho- 
monas. Ibid., 23:129. 

(1934) The experimental infection of Amphibia with cultures 

of Trichomonas. Ibid., 26:26. 

— (1935) Observations upon a "trichomonas" from pond water. 
Ibid., 27:246. 

— (1936) Further observations upon a "Trichomonas" from 

pond water. Ibid., 28:443. 

(1939) A note upon the systematic position of "Trichomonas" 

keilini. Ibid., 31:469. 

Boeck, W. C: (1921) Chilomastix mesnili and a method for its cul- 
ture. J. Exper. Med., 33:147. 
and Tanabe, M.: (1926) Chilomastix gallinarum, morphol- 
ogy, division and cultivation. Am. J. Hyg., 6:319. 

Bunting, Martha: (1926) Studies of the life-cycle of Tetramitus 
rostratus. J. Morphol. Physiol., 42:23. 

and Wenrich, D. H.: (1929) Binary fission in the amoeboid 

and flagellate phases of Tetramitus rostratus. Ibid., 47:37. 

Cleveland, L. R.: (1935) The intranuclear achromatic figure of 
Oxymonas grandis sp. nov. Biol. Bull., 69:54. 
— (1938) Mitosis in Pyrsonympha. Arch. Protist,, 91:452. 

(1950) Hormone-induced sexual cycle of flagellates. II. J. 

Morphol., 86:185. 

(1950a) III. Ibid., 86:215. 

(1950b) IV. Ibid., 87:317. 

Hall, S. R., Sanders, E. P. and Collier, J.: (1934) The 

wood-feeding roach, Cryptocercus, its Protozoa, etc. Mem. Am. 

Acad. Arts and Sc, 17:185. 
Connell, F. H.: (1930) The morphology and life-cycle of Oxymonas 

dimorpha, etc. Univ. daiifornia Publ. Zool., 36:51. 
da Fonseca, O. O. R.: (1915) Sobre os flagellados dos mammiferos 

do Brazil. Brazil Medico, 29:281. 
Davis, H. S.: (1925) Octomitus salmonis, a parasitic flagellate of 

trout. Bull. Bur. Fisher., 42:9. 
— (1943) A new polymastigine flagellate, Costia pyriformis, 

parasitic on trout. J. Parasit., 29:385. 


Dobell, C: (1934) Researches on the intestinal Protozoa of mon- 
keys and man. VI. Parasitology, 26:531. 

— (1935) VII. Ibid., 27:564. 

— (1939) The common flagellate of the human mouth, Tricho- 
monas tenax (O.F.M.): etc. Ibid., 31:138. 

-and O'Connor, F. W.: (1921) The intestinal Protozoa of 

man. London. 
Dogiel, V.: (1916) Researches on the parasitic Protozoa from the 

intestine of termites. I. J. russ. zool., 1:1. 
Donne, A.: (1836) Animalcules observes dans les matieres puru- 

lentes et le produit des secretions des organes genitaux de 

l'homme et de la femme. C. R. Acad. Sc, 3:385. 
Duboscq, O. and Grasse, P.: (1925) Appareil de Golgi, mitochon- 

dries, etc. C. R. Soc. Biol., 93:345. 
Feo, L. G. : (1944) The incidence and significance of Trichomonas 

vaginalis in the male. Am. J. Trop. Med., 24:195. 
Filice, F. P.: (1952) Studies on the cytology and life history of a 

Giardia from the laboratory rat. Uni. Cal. Publ. Zool., 57:53. 
FoA, Anna: (1905) Due nuovi flagellati parassiti (Nota prelim.). 

Rend. Ace. Lincei, 14:542. 
Galli-Valerio, B. : (1903) Notes de parasitologic. Centralbl. Bakt. 

I. Orig., 35:81. 
Geiman, Q. M.: (1935) Cytological studies of the Chilomastix of 

man and other mammals. J. Morphol., 57:429. 
Grasse, P. P.: (1926) Contribution a l'etude des flagell^s parasites. 

Arch. zool. exper. gen., 65:345. 

— (1952) Traite de zoologie. I. Fasc. 1. Paris. 

— (1952a) Ordre des Trichomonadines. In: Grasse (1952), p. 

— and Faure, Alice: (1939) Quelques donnees nouvelles sur 
la cytologie et la reproduction de Trichomonas caviae. Bull. biol. 
France et Belg., 73: 1. 

Grassi, B.: (1917) Flagellati nei Termitidi. Mem. R. Ace. Lincei, 
Ser. 5, 12:331. 

— -and FoA, Anna: (1911) Intorno ai protozoi dei termitidi 
(n.p.). Rend. R. Ace. Lincei, S. V. CI. Sc. fils, 20:725. 

Hawes, R. S.: (1947) On the structure, division, and systematic po- 
sition of Trichomonas vaginalis Donne, with a note on its meth- 
ods of feeding. Quart. J. Micr. Sc, 88:79. 

Hegner, R. W. : (1922) A comparative study of the Giardias living 
in man, rabbit, and dog. Am. J. Hyg., 2:442. 

— (1923) Giardias from wild rats and mice and Giardia caviae 
sp. n. from the guinea-pig. Ibid., 3:345. 

Hogue, Mary J.: (1938) The effect of Trichomonas foetus on tissue 
culture cells. Am. J. Hyg., 28:288. 

— (1943) The effect of Trichomonas vaginalis on tissue culture 
cells. Ibid., 37:142. 

Hollande, A. V.: (1939) Sur un genre nouveau de Trichomonadide 

libre: etc. Bull. soc. zool. France, 64:114. 
Hsiung, T. S.: (1930) A monograph on the Protozoa of the large 

intestine of the horse. Iowa State College J. Sc, 4:356. 


Hunninen, A. V. and Wichterman, R. : (1938) Hyperparasitism: a 
species of Hexamita found in the reproductive systems, etc. 
J. Parasit., 24:95. 

Janicki, C: (1911) Zur Kenntnis des Parabasalapparats bei para- 
sitischen Flagellaten. Biol. Centralbl., 31:321. 

— (1915) Untersuchungen an parasitischen Flagellaten. II. 
Ztschr. wiss. Zool., 112:573. 

Kimura, G. G.: (1934) Cochlosoma rostratum sp. nov., etc. T. Am. 

Micr. Soc, 53:102. 
Kirby, H. Jr.: (1924) Morphology and mitosis of Dinenympha 

Jimbriata. Univ. California Publ. Zool., 26:199. 

— (1926) On Staurojoenina assimilis sp.n. Ibid., 29:25. 

— (1926a) The intestinal flagellates of the termite, Cryptotermes 
hermsi. Ibid., 29:103. 

— (1928) A species of Proboscidiella from Kalotermes, etc. 
Quart. J. Micr. Sc, 72:355. 

— (1929) Snyderella and Coronympha, etc. Uni. Cal. Publ. 
Zool., 31:417. 

— (1930) Trichomonad flagellates from termites. I. Ibid., 33: 

— (1931) II. Ibid., 36:171. 

— (1932) Two Protozoa from brine. Tr. Am. Micr. Soc, 51:8. 

— (1936) Two polymastigote flagellates of the genera Pseudo- 
devescovina and Caduceia. Quart. J. Micr. Sc, 79:309. 

(1937) The devescovinid flagellate Parajoenia grassii from a 

Hawaiian termite. Univ. California Publ. Zool., 41:213. 

— (1938) Polymastigote flagellates of the genus Foaia Janicki, 
etc. Quart. J. Micr. Sc, 81:1. 

— (1939) Two new flagellates from termites in the genera 
Coronympha Kirby, etc. Proc California Acad. Sc, 22:207. 

— (1941) Devescovinid flagellates of termites. I. Univ. Cali- 
fornia Publ. Zool., 45:1. 

— ■ (1942) II. Ibid., 45:93. 

— (1942a) III. Ibid., 45:167. 

— (1943) Observations on a trichomonad from the intestine of 
man. J. Parasit., 29:422. 

— (1944) Some observations on cytology and morphogenesis in 
flagellate Protozoa. J. Morphol, 75:361. 

— (1945) The structure of the common intestinal trichomonad 
of man. Jour. Parasit., 31:163. 

— (1946) Gigantomonas herculea. Uni. Cal. Publ. Zool., 53:163. 

— (1947) Flagellate and host relationships of trichomonad fla- 
gellates. J. Parasit., 33:214. 

— (1949) Devescovinid flagellates of termites. V. Univ. Cali- 
fornia Publ. Zool., 45:319. 

— (1951) Observations on the trichomonad flagellate of the re- 
productive organs of cattle. J. Parasit., 37:445. 

and Honigberg, B.: (1949) Flagellates of the caecum of 

ground squirrels. Univ. California Publ. Zool., 53:315. 
Klug, G.: (1936) Neue oder wenig bekannte Arten der Gattungen 
Mastigamoeba, etc Arch Protist., 87:97. 


Kofoid, C. A. and Christiansen, E. B.: (1915) On binary and mul- 
tiple fission in Giardia muris. Univ. California Publ. Zool., 16: 

- and Swezy, Olive: (1915) Mitosis and multiple fission in 
trichomonad flagellates. Proc. Am. Acad. Arts and Sc, 

(1920) On the morphology and mitosis of Chilomastix 

mesnili, etc. Univ. California Publ. Zool., 20:117. 

(1922) Mitosis and fission in the active and encysted 

phases of Giardia enterica, etc. Ibid., 20:199. 

- (1920) On Proboscidiclla multinucleata, etc. Ibid., 20: 


Koidzumi, M.: (1921) Studies on the intestinal Protozoa found in 
the termites of Japan. Parasitology, 13:235. 

Kotlan, A.: (1923) Zur Kenntnis der Darmflagellaten aus der 
Hausente und anderen Wasservogeln. Centralbl. Bakt. I. Orig., 

Kozloff, E. N.: (1945) The morphology of Trichomonas limacis. J. 
Morphol., 77:53. 

Kuczynski, M. H.: (1918) Ueber die Teilungsvorgange verschie- 
dener Trichomonaden, etc. Arch. Protist., 39:107. 

Lambl, W. : (1859) Mikroskopische Untersuchungen der Darm- 
Excrete. Vierteljahrschr. prakt. Heilk., 61:1. 

Lavier, G.: (1924) Deux especes de Giardia, etc. Ann. Parasit., 2: 

Leidy, J.: (1877) On intestinal parasites of Tcrmes flavipes. Proc. 
Acad. Nat. Sc, Philadelphia, p. 146. 

Levine, N. D., Boley, L. E. and Hester, H. R.: (1941) Experi- 
mental transmission of Trichomonas gallinae from the chicken 
to other birds. Am. J. Hyg., 33:23. 

— and Brandly, C. A.: (1940) Further studies on the patho- 
genicity of Trichomonas gallinae for baby chicks. Poultry Sc, 

Light, S. F.: (1926) On Metadevescovina debilis g. n., sp. n. Univ. 
California Publ. Zool., 29:141. 

Lynch, K. M.: (1922) Tricercomonas intestinalis and Enter omonas 
caviae n. sp., etc. J. Parasit., 9:29. 

Martin, C. H. and Robertson, Muriel: (1911) Further observa- 
tions on the caecal parasites of fowls. Quart. J. Micr. Sc, 57:53. 

McNeil, Ethel and Hinshaw, W. R.: (1942) Cochlosoma rostratum 
from the turkey. J. Parasit., 28:349. 

and Kofoid, C. A.: (1941) Hexamita meleagridis sp. 

nov. from the turkey. Am. J. Hyg., 34:71. 

Moore, Emmeline: (1922) Octomitus salmonis, a new species of in- 
testinal parasite in trout. Tr. Am. Fish. Soc, 52:74. 
— (1923) Diseases of fish in State hatcheries. Rep. Bur. Prev. 
Stream Poll., New York, 12:18. 

Morgan, B. B. and Noland, L. E.: (1943) Laboratory methods for 
differentiating Trichomonas foetus from other Protozoa in the 
diagnosis of trichomoniasis in cattle. J. Am. Vet. Med. Assoc, 


Nie, D.: (1950) Morphology and taxonomy of the intestinal Proto- 
zoa of the guinea-pig, Cavia porcella. J. Morphol., 86:381. 

Nieschulz, O. and Krijgsman, B. J.: (1925) Ueber Giardia simoni 
Lavier. Arch. Protist., 52:16(5. 

Powell, W. N.: (1928) On the morphology of Pyrsonympha with a 
description of three new species, etc. Univ. California Publ. 
Zool., 31:179. 

Rees, C. W. : (1938) Observations on bovine venereal trichomoni- 
asis. Veter. Med., 33:321. 

Reuling, F.: (1921) Zur Morphologie von Trichomonas vaginalis. 
Arch. Protist., 42:347. 

Rosenberg, L. E.: (1936) On the viability of Tritrichomonas augusta. 
Tr. Am. Micr. Soc, 55:313. 

Samuels, R. : (1941) The morphology and division of Trichomonas 
augusta. Ibid., 60:421. 

Schmidt, W.: (1920) Untersuchungen iiber Octomitus intestinalis. 
Arch. Protist., 40:253. 

Simon, C. E.: (1921) Giardia enterica: etc. Am. J. Hyg., 1:440. 

— (1922) A critique of the supposed rodent origin of human 
giardiasis. Ibid., 2:406. 

Stabler, R. M.: (1941) The morphology of Trichomonas gallinae 
( = columbae). J. Morphol, 69:501. 
(1951) Effect of Trichomonas gallinae from diseased mourn- 
ing doves on clean domestic pigeons. J. Parasit., 37:473. 

— and Engley, F. B.: (1946) Studies on Trichomonas gallinae 
infections in pigeon squabs. J. Parasit., 32:225. 

Feo, L. G. and Rakoff, A. E.: (1941) Implantation of in- 

testinal trichomonads (T. hominis) into the human vagina. Am. 
J. Hyg., 34:114. 

— and Pennypacker, M. I.: (1939) A brief account of Tricho- 
monas augusta, etc. Tr. Am. Micr. Soc, 58:391. 

Sutherland, J. L.: (1933) Protozoa from Australian termites. 
Quart, J. Micr. Sc, 76:145. 

Tavolga, W. N. and Nigrelli, R. F.: (1947) Studies on Costia 
necatrix. Tr. Am. Micr. Soc, 66:366. 

Theiler, H. and Farber, S. M.: (1932) Trichomonas muris, para- 
sitic in Oxyurids of the white mouse. J. Parasit., 19: 169. 

Trager, W. : (1934) A note on the cultivation of Tricercomitus 
termopsidis, etc. Arch. Protist., 83:264. 

Travis, B. V. : (1932) A discussion of synonymy in the nomenclature 
of certain insect flagellates, etc. Iowa State College J. Sc, 6:317. 

— (1932a) Trichomonas phasiani, a new flagellate from the 
ring-necked pheasant, etc. J. Parasit., 18:285. 

— (1934) Karotomorpha, a new name for Tetramastix, etc. Tr. 
Am. Micr. Soc, 53:277. 

— (1939) Descriptions of five new species of flagellate Protozoa 
of the genus Giardia. J. Parasit., 25:11. 

Trussell, R. E.: (1947) Trichomonas vaginalis and trichomoniasis. 
Springfield, Illinois. 

— and Johnson, G.: (1945) Trichomonas vaginalis Donne. Re- 


cent experimental advances. Puerto Rico J. P. H. Trop. Med., 

Tsuchiya, H. and Andrews, J. : (1930) A report on a case of giardi- 
asis. Am. J. Hyg., 12:297. 

Waters, P. C. Fiene, A. R. and Becker, E. R.: (1940) Strains in 
Giardia ondatrae Travis. Tr. Am. Micr. Soc, 59:160. 

Weissenberg, R. : (1912) Callimastix cyclopis n.g., n.sp., etc. Ber- 
lin. Sitz.-Ber. Ges. naturf. Freunde, p. 299. 

Wenrich, D. H.: (1921) The structure and division of Trichomonas 
muris. J. Morphol., 36:119. 

(1932) The relation of the protozoan flagellate, Retortamonas 

gryllotalpae, etc. Tr. Am. Micr. Soc, 51:225. 

— (1944) Comparative morphology of the trichomonad flagel- 
lates of man. Am. J. Trop. Med., 24:39. 

— (1944a) Morphology of the intestinal trichomonad flagellates 

in man and of similar forms in monkeys, cats, dogs and rats. 
J. Morphol., 74:189. 

(1947) The species of Trichomonas in man. J. Parasit., 


and Emmerson, M. A.: (1933) Studies on the morphology of 

Tritrichomonas foetus (Riedmiiller) from American cows. J. 
Morphol., 55:193. 

-and Saxe, L. H.: (1950) Trichomonas microti n.sp. J. 

Parasit., 36:261. 

Wenyon, C. M.: (1926) Protozoology. 1. London and Baltimore. 

Zeliff, C. C: (1930) A cytological study of Oxymonas, etc. Am. J. 
Hyg., 11:714. 

(1930a) KirbyeUa zeteki, etc. Ibid., 11:740. 

Chapter 16 
Order 4 Hypermastigina Grassi and Foa 

ALL members of this order are inhabitants of the alimentary 
. canal of termites, cockroaches, and woodroaches. The cyto- 
plasmic organization is of high complexity, although there is only 
a single nucleus. Flagella are numerous and have their origin in the 
blepharoplasts located in the anterior region of body. In many spe- 
cies which are xylophagous, there exists a true symbiotic relationship 
between the host termite and the protozoans (p. 29). Method of 
nutrition is either holozoic or saprozoic (parasitic). Bits of wood, 
starch grains, and other food material are taken in by means of 
pseudopodia (p. 99). 

Asexual reproduction is by binary fission; multiple division has 
also been noted in some species under certain conditions, while sexual 
reproduction has been observed in a few species. Encystment occurs 
in some genera of Lophomonadidae and certain species inhabiting 
woodroaches in which moulting of the host insect leads to encyst- 
ment and sexual reproduction. The protozoan fauna of the colon is 
lost at the time of molting of the host insect, but newly molted indi- 
viduals regain the fauna by proctodeal feeding (Andrews, 1930). 

The number of Protozoa present in the colon of the termite is 
usually very enormous. The total weight of all Protozoa present in a 
termite worker has been estimated to be from about 1/7-1/4 (Hun- 
gate, 1939) or 1/3 (Katzin and Kirby, 1939) to as much as 1/2 
(Cleveland, 1925) of the body weight of the host. The correlation- 
ship between the termite and its intestinal flagellate fauna, has been 
studied by several observers. Kirby (1937) notes that certain groups 
of flagellates occur only in certain groups of termites, while others 
are widely distributed. Flagellates of one host termite introduced 
into individuals of another species survive for a limited time only 
(Light and Sanford, 1928; Cleveland, Hall et al., 1934; Dropkin, 
1941, 1940). Taxonomy (Koidzumi, 1921; Kirby, 1920; Bernstein, 

Body without segmented appearance 

Flagella in spiral rows Family 1 Holomastigotidae (p. 405) 

Flagella not arranged in spiral rows 
Flagella in one or more anterior tufts 

1 tuft of flagella Family 2 Lophomonadidae (p. 407) 

2 tufts of flagella Family 3 Hoplonymphidae (p. 410) 

4 tufts of flagella Family 4 Staurojoeninidae (p. 412) 

Several tufts (loriculae) Family 5 Kofoidiidae (p. 412) 




Flagella not arranged in tufts 

Posterior part without flagella 

Family 6 Trichonymphidae (p. 412) 

Flagella over entire body.. .Family 7 Eucomonymphidae (p. 414) 
Body with segmented appearance. .Family 8 Teratonymphidae (p. 414) 

Family 1 Holomastigotidae Janicki 

Genus Holomastigotes Grassi. Body small; spindle-shaped; few 
spiral rows reach from anterior to posterior end; nucleus anterior, 
surrounded by a mass of dense cytoplasm; saprozoic; in the termite 

H. elongatum G. (Fig. 171, a). In gut of Reticulitermes lucifugus, 
R. speratus, R. flaviceps, and Macrohodotermes massambicus; up to 
70/x by 24m (Grassi, 1892). 

Fig. 171. a, Holomastigotes elongatum, X700 (Koidzumi); b, Holo- 
mastigotoides hartmanni, X250 (Koidzumi); c, Spirotrichonympha leidyi, 
X400 (Koidzumi); d, S. pulchella, X900 (Brown); e, Microspirotricho- 
nympha porteri, X250 (Koidzumi); f, M. ovalis, X600 (Brown); g, Macro- 
spironympha xylopletha, X300 (Cleveland et al.); h, Leptospironympha 
eupora, X1050 (Cleveland et al.). 


Genus Holomastigotoides Grassi and Foa. Large; pyriform; 
spiral rows of flagella as in the last genus, but more numerous (12-40 
rows) ; a mass of dense cytoplasm surrounds ovoid nucleus near the 
anterior end; in termite gut (Grassi and Foa, 1911). Cytology (Cleve- 
land, 1949). 

H. hartmanni Koidzumi (Fig. 171, b). 50-140^ long; in Copto- 
termes formosanus. 

H. tusitala Cleveland (Figs. 62; 63; 64; 172, a, 6). In the hindgut 
of Prorhinotermes simplex; largest species in this host; elongate pyri- 
form; five flagellar bands, arise at the anterior end and spiral the 
body 5| times; dimorphic with respect to chromosome numbers, 
2 and 3; 130-200 m long. Cleveland's observation on its chromosome 
cycle has been mentioned elsewhere (p. 158). 

Genus Spirotrichonympha Grassi and Foa (1911). Moderately 
large; elongate pyriform; flagella deeply embedded in cytoplasm in 
anterior region, arising from 1 to several spiral bands; mass of dense 
cytoplasm conical and its base indistinct; nucleus spherical; in ter- 
mite gut. Development (Duboscq and Grasse, 1928). 

S. leidyi Koidzumi (Fig. 171 ,c). In Coptotermes formosanus; 15-50/z 
by 8-30ju. 

S. pulchella Brown (Fig. 171, d). 36-42 M by 14-16/x; in Reticu- 
litermes hageni. 

S. bispira Cleveland. In Kalotermes simplicicornis ; 59-102^ by 
32-48m; two flagellar bands in 34 spiral turns; resting nucleus with 
two chromosomes; the cytoplasmic division is unique in that portion 
of the anterior end shifts its position to the posterior end, where a 
new flagellar band develops; thus the division is longitudinal (Cleve- 
land, 1938). 

Genus Spirotrichonymphella Grassi. Small; without spiral ridges; 
flagella long; saprozoic, not wood-feeding; in termite gut. 

S. pudibunda G. In Porotermes adamsoni; Australia. Multiple 
fusion (Sutherland). 

Genus Micro spirotrichonympha Koidzumi (Spironympha Koid- 
zumi). Small, surface not ridged; spiral rows of flagella only on 
anterior half; a tubular structure between nucleus and anterior 
extremity; a mass of dense cytoplasm surrounds nucleus; with or 
without axial rod; in termite gut (Koidzumi, 1917, 1921). 

M. porteri K. (Fig. 171, e). In Reticulitermes flaviceps ; 20-55^ by 


M. ovalis (Brown) (Fig. 171,/). 36-48/1 by about 40/z; in Reticu- 
litermes hesperus (Brown, 1931). 

Genus Spirotrichosoma Sutherland. Pyriform or elongate; below 


operculum, two deeply staining rods from which fiagella arise and 
which extend posteriorly into 2 spiral flagellar bands; without axo- 
style; nucleus anterior, median; wood chips always present, but 
method of feeding unknown; in Stolotermes victoriensis; Australia. 

S. capitata S. 87/x by 38/*; flagellar bands closely spiral, reach 
posterior end. 

Genus Macrospironympha Cleveland et al. Broadly conical: fia- 
gella on 2 broad flagellar bands which make 10-12 spiral turns, 2 inner 
bands; axostyles 36-50 or more; during mitosis nucleus migrates 
posteriorly; encystment, in which only nucleus and centrioles are 
retained, takes place at each ecdysis of host; in Cryptocercus punctu- 

M. xylopletha C. et al. (Fig. 171, g). 112-154 M by 72-127 M . 

Genus Leptospironympha Cleveland et al. Cylindrical; small; fia- 
gella on 2 bands winding spirally along body axis; axostyle single, 
hyaline; in Cryptocercus punctulatus. Several species. Sexual repro- 
duction (Cleveland, 1951). 

L. eupora C. et al. (Fig. 171, h). 30-38/z by 18-21/i. 

Genus Rostronympha Duboscq, Grasse and Rose. Form variable, 
ovoid to medusoid; with or without a long contractile attaching 
organelle like a trunk, constricted in three places and of annulated 
surface; spiral ridges from which fiagella arise, do not reach the pos- 
terior half; posterior half with attached spirochaetes; xylophagous; 
in the intestine of Anacanthotermes in Algier. 

R. magna D., G. and R. (Fig. 172, c-e). Large individuals, 135- 
180m by 110-135/x, with the trunk-like extension reaching a length of 
180yu; the body proper is divided into two parts; the posterior portion 
may be drawn out like the manubrium of a medusa; axostyle con- 
spicuous; in the gut of Anacanthotermes ochraceus of Algier (Duboscq 
and Grasse, 1943). 

Family 2 Lophomonadidae Kent 

Genus Lophomonas Stein. Ovoid or elongate; small: a vesicular 
nucleus anterior; axostyle composed of many filaments; cysts com- 
mon; in colon of cockroaches. 

L. blattarum S. (Figs. 24, a; 65; 72; 173, a-e). Small pyriform, 
plastic; bundle of axostylar filaments may project beyond the pos- 
terior end; active movements; binary or multiple fission; 25-30/1 
long; encystment; holozoic; in the colon of cockroaches, Blatta orien- 
talis in particular; widely distributed (Kudo, 1926). Cytology (Ja- 
nicki, 1910; Belaf, 1926; Kudo, 1926). 

L. striata Biitschli (Fig. 173, f-h). Elongate spindle; body with 



obliquely arranged needle-like structures which some investigators 
believe to be a protophytan (to which Grasse gave the name, Fusi- 
formis lophomonadis) ; bundle of axial filaments short, never protrud- 
ing; movement sluggish; cyst spherical with needle-like structures; 
in same habitat as the last species. Cytology (Kudo, 1926a). 


' ? 

Fig. 172. a, b, Holomastigotoides tusitala (Cleveland) (a, surface view; 
b, flagellar bands, parabasal bodies, thin axostyles) ; c-e, Rostronympha 
magna (Duboscq and Grasse) (c, a large individual with the completely 
extended trunk, with axostyle, X500; d, a small medusoid form, XI 000; 
e, a young individual with posteriorly attached spirochaetes, X500); f, 
anterior end of Joenia annectens (Duboscq and Grasse). 

Genus Eulophomonas Grassi and Foa. Similar to Lophomonas, but 
flagella vary from 5-15 or a little more in number; in termite gut. 

E. kalotermitis Grassi. In Kalotermes flavicollis; this flagellate has 
not been observed by other workers. 

Genus Prolophomonas Cleveland et al. Similar to Eulophomonas; 
established since Eulophomonas had not been seen by recent observ- 
ers; it would become a synonym "if Eulophomonas can be found in 
K. flavicollis" (Cleveland et al.). 



P. tocopola C. et al. (Fig. 173, i). 14-19/i by 12-15/*; in Cr?/pto- 
cercus punctidatus. 

Genus Joenia Grassi. Ellipsoidal; anterior portion capable of 
forming pseudopodia; flagellar tufts in part directed posteriorly; 
surface covered by numerous immobile short filamentous processes, 

Fig. 173. a-e, Lophomonas blattarum (a, b, in life, X320; c, a stained 
specimen; d, a trophozoite in which the nucleus is dividing; e, a stained 
cyst, X1150) (Kudo); f-h, L. striata (f, in life, X320; g, a stained divid- 
ing individual; h, a stained cyst, XI 150) (Kudo); i, Prolophomonas toco- 
pola, X1200 (Cleveland et al.); j, Joenia annectens (Grassi and Foa); k, 
Microjoenia pyriformis, X920 (Brown); 1, Torquenympha octophis, X920 

nucleus spherical, anterior; posterior to it a conspicuous axostyle 
composed of numerous axial filaments, a parabasal apparatus sur- 
rounding it; xylophagous; in termite gut (Grassi, 1885). 

J. annectens G. (Figs. 172, /; 173, j). In Kalotermes flavicollis. 
Parabasal apparatus (Duboscq and Grasse, 1928a). 


Genus Joenina Grassi. More complex in structure than that of 
Joenia; flagella inserted at anterior end in a semi-circle; parabasal 
bodies 2 elongated curved rods; xylophagous (Grassi, 1917). 

J. pulchella G. In Porotermes adamsoni. 

Genus Joenopsis Cutler. Oval; large; a horseshoe-shaped pillar at 
anterior end, flagella arising from it; some directed anteriorly, others 
posteriorly; parabasal bodies long rods; a strong axostyle; xylopha- 
gous; in the termite gut (Cutler, 1920). 

J. polytricha C. In Archotermopsis wroughtoni; 95-129/z long. 

Genus Microjoenia Grassi. Small, pyriform; anterior end flat- 
tened; flagella arranged in longitudinal rows; axostyle; parabasal 
body simple; in termite gut (Grassi, 1892). 

M. pyriformis Brown (Fig. 173, k). 44-52 n by 24-30/x; in Reticuli- 
termes hageni (Brown, 1930). 

Genus Mesojoenia Grassi and Foa. Large; flagellar tuft spreads 
over a wide area; distinct axostyle, bent at posterior end; 2 para- 
basal bodies; in termite gut (Grassi and Foa, 1911). 

M . decipiens G. In Kalotcrmes flavicollis. 

Genus Torquenympha Brown. Small; pyriform or top-form; axo- 
style; radially symmetrical; 8 radially arranged parabasal bodies; 
nucleus anterior; in termite gut (Brown, 1930). 

T. octoplus B. (Fig. 173, I). 15-26/x by 9-13/z; in Reticulitermes 

Family 3 Hoplonymphidae Light 

Genus Hoplonympha Light. Slender fusiform, covered with thick, 
rigid pellicular armor; each of the two flagellar tufts arises from a 
plate connected with blepharoplast at anterior end; nucleus near 
anterior extremity, more or less triangular in form; in termite gut 
(Light, 1926). 

H. natator L. (Fig. 174, a, b). 60-120/x by 5-12/x; in Kalotermes 

Genus Barbulanympha Cleveland et al. Acorn-shaped: small, nar- 
row, nuclear sleeve between centrioles; number of rows of flagella 
greater at base; large chromatin granules; numerous (80-350) para- 
basals; axostylar filaments 80-350; flagella 1500-13,000; different 
species show different number of chromosomes during mitosis; in gut 
of Cryptocercus punctulatus. Four species. 

B. ujalula C. et al. (Figs. 61; 174, c). 250-340 M by 175-275 M ; 50 
chromosomes; flagellated area 36-41ju long; centriole 28-35^ long. 

B. laurabuda C. et al. 180-240^ by 135-170/z; 40 chromosomes; 
flagellated area 29-33/z long; centriole 24-28^ long. 



Genus Rhynchonympha Cleveland et al. Elongate; number of fla- 
gellar rows same throughout; axial filaments somewhat larger and 
longer, about 30; 30 parabasals: 2400 flagellar in Cryplocercus punc- 
tulatus. Sexual cycle (Cleveland, 1952). 

R. tarda C. et al. (Fig. 175,/). 130-215 M by 30-70 M . 

Genus Urinympha Cleveland et at. Narrow, slender; flagellated 
area, smaller than that of the two genera mentioned above; flagella 
move as a unit; about 24 axial filaments; 24 parabasals; 600 flagella; 

Fig. 174. a, b, Hoplonympha natator, X450 (Light); c, Barbulanympha 
ufalula, X210 (Cleveland etal.); d, Urinympha talea, X350 (Cleveland 
et al.); e, Staurojoenina assimilis, X200 (Kirby); f, Idionympha perissa, 
X250 (Cleveland et al.); g, Teratonympha mirabilis, X200 (Dogiel). 


in gut of Cryptocercus punctulatus (Cleveland, 1951a). 

U. talea C. (Fig. 174, d). 7 5-300 /i by 15-50/t; sexual reproduction 
(Cleveland, 1951a). 

Family 4 Staurojoeninidae Grassi 

Genus Staurojoenina Grassi. Pyriform to cylindrical; anterior 
region conical; nucleus spherical, central; 4 flagellar tufts from ante- 
rior end; ingest wood fragments; in termite gut (Grassi, 1917). 

S. assimilis Kirby (Fig. 174, e). 105-190/z long; in Kalotermes 
minor (Kirby, 1926). 

Genus Idionympha Cleveland et al. Acorn-shaped; axostyles 8-18; 
fine parabasals grouped in 4 areas; pellicle non-striated; nucleus 
nearer anterior end than that of Staurojoenina; flagellated areas 
smaller; in gut of Cryptocercus punctulatus. 

I. perissa C. et. al (Fig. 174,/). 169-275/* by 98-155/t. 

Family 5 Kofoidiidae Light 

Genus Kofoidia Light. Spherical; flagellar tufts composed of 8-16 
loriculae (permanently fused bundles of flagella); without either 
axostyle or parabasal body; between oval nucleus and bases of 
flagellar tufts, there occurs a chromatin collar; in termite gut (Light, 

K. loriculata L. (Fig. 175, a, b). 60-140/z in diameter; in Kalotermes 

Family 6 Trichonymphidae Kent 

Genus Trichonympha Leidy (Leidyonella Frenzel; Gymnonympha 
Dobell; ? Leidy opsis Kofoid and Swezy). Anterior portion consists 
of nipple and bell, both of which are composed of 2 layers; a distinct 
axial core; nucleus central; flagella located in longitudinal rows on 
bell; xylophagous; in the intestine of termites and woodroach. Many 
species. The species inhabiting the woodroach undergo sexual repro- 
duction at the time of molting of the host (Cleveland, 1949a) (p. 
185). Species (Leidy, 1877; Kirby, 1932, 1944) ; nomenclature (Cleve- 
land, 1938; Dobell, 1939); mineral ash (MacLennan and Murer, 

T. campanula Kofoid and Swezy (Figs. 60; 175, c). 144-313/z by 
57-1 44/t; wood particles are taken in by posterior region of the body 
(Fig. 35, a); in Zootermopsis angusticollis, Z. nevadensis and Z. 
laticeps (Kofoid and Swezy, 1919). 

T. agilis Leidy (Fig. 175, d). 55-1 15/t by 22-45/*; in Reticulitermes 
flavipes, R. lucifugus, R. speratus, R. flaviceps, R. hesperus, R. tibialis. 
(Leidy, 1877). 



T. grandis Cleveland et al. 190-205^ by 79-88^; in Cryptocercus 

Genus Pseudotrichonympha Grassi and Foa. 2 parts in anterior 
end as in Trichonympha; head organ with a spherical body at its tip 
and surrounded by a single layer of ectoplasm; bell covered by 2 
layers of ectoplasm; nucleus lies freely; body covered by slightly 

Fig. 175. a, b, Kofoidia loriculata, X175, X300 (Light); c, Tricho- 
nympha campanula, X150 (Kofoid and Swezy); d, T. agilis, X410 
(Kirby); e, Eucomonympha imla, X350 (Cleveland et al.); f, Rhyncho- 
nympha tarda, X350 (Cleveland et al.). 


oblique rows of short fiagella; in termite gut (Grassi and Foa, 1911). 

P. grassii Koidzumi. In Coptotermes formosanus; spindle-form; 
200-300^ by 50-1 20/x (Koidzumi, 1921). 

Genus Deltotrichonympha Sutherland. Triangular; with a small 
dome-shaped "head"; composed of 2 layers; head and neck with long 
active fiagella; body fiagella short, arranged in 5 longitudinal rows; 
fiagella absent along posterior margin; nucleus large oval, located 
in anterior third; cytoplasm with wood chips; in termite gut. One 

D. operculata S. Up to 230/* long, 164/* wide, and about 50/x thick; 
in gut of Mastotermes darwiniensis; Australia. 

Family 7 Eucomonymphidae Cleveland et al. 

Genus Eucomonympha Cleveland et al. Body covered with fiagella 
arranged in 2 (longer rostral and shorter post-rostral) zones; rostral 
tube very broad, filled with hyaline material; nucleus at base of 
rostrum; in gut of Cryptocercus punctulatus. 

E. imla C. et al. (Fig. 175, e). 100-165/* by 48-160/*; attached 
forms more elongate than free individuals; sexual reproduction 
(Cleveland, 1950). 

Family 8 Teratonymphidae Koidzumi 

Genus Teratonympha Koidzumi (Teranympha K.; Cyclonympha 
Dogiel). Large and elongate; transversely ridged, and presents a 
metameric appearance; each ridge with a single row of fiagella; an- 
terior end complex, containing a nucleus; reproduction by longitudi- 
nal fission; in termite gut (Koidzumi, 1917, 1921; Dogiel, 1917). 

T. mirabilis K. (Fig. 174, g). 200-300/* or longer by 40-50/*; in Re- 
ticulitermes speratus. Mitosis (Cleveland, 1938a). 


Andrews, Bess J.: (1930) Method and rate of protozoan refauna- 
tion in the termite, etc. Univ. California Publ. Zool., 33:449. 

Belar, K.: (1926) Der Formwechsel der Protistenkerne. Ergebn. u. 
Fortschr. Zool., 6:235. 

Bernstein, T.: (1928) Untersuchungen an Flagellaten aus dem 
Darmkanal der Termiten aus Turkestan. Arch. Protist., 61:9. 

Brown, V. E.: (1930) Hypermastigote flagellates from the termites 
Reticulitermes: etc. Univ. California Publ. Zool., 36:67. 

(1930a) On the morphology of Spirotrichonympha with a de- 
scription of two new species, etc. Arch. Protist., 70:517. 

(1931) The morphology of Spironympha, etc. J. Morphol. 

Phvsiol., 51:291. 


Cleveland, L. R. : (1925) The effects of oxygenation and starvation 
on the symbiosis between the termite, Termopsis, and its in- 
testinal flagellates. Biol. Bull., 48:455. 

— (1938) Longitudinal and transverse division in two closely 
related flagellates. Ibid., 74:1. 

(1938a) Morphology and mitosis of Tetranympha. Arch. 

Protist., 91:442. 

(1949) The whole life cycle of chromosomes and their coiling 

systems. Tr. Am. Philos. Soc, 39:1. 

(1949a) Hormone-induced sexual cycles of flagellates. I. J. 

Morphol., 85:197. 

(1950) V. Ibid., 87:349. 

(1951) VI. Ibid., 88:199. 

(1951a) VII. Ibid., 88:385. 

- (1952) VIII. Ibid., 91:269. 
Hall, S. R., Sanders, E. P. and Collier, Jane: (1934) The 

wood-feeding roach, Cryptocercus, its Protozoa, etc. Mem. Am. 

Acad. Arts and Sc., 17:185. 
Cutler, D. W. : (1920) Protozoa parasitic in termites. II. Quart. J. 

Micr. Sc, 64:383. 
Dobell, C: (1939) On "Teranympha" and other monstrous latin 

parasites. Parasitology, 31:255. 
Dogiel, V. A.: (1917) Cyclonympha strobila n. g., n. sp. J. Microbiol., 

■ (1922) Untersuchungen an parasitischen Protozoen aus dem 

Darmkanal der Termiten. II, III. Arch. Soc. Russ. Protist., 1 : 

Dropkin, V. H.: (1937) Host-parasite relations in the distribution of 

Protozoa in termites. Univ. California Publ. Zool., 41 : 189. 
(1941) Host specificity relations of termite Protozoa. Ecol- 
ogy, 22:200. 
(1946) The use of mixed colonies of termites in the study of 

host-symbiont relations. J. Parasit., 32:247. 
Duboscq, O. and Grasse, P.: (1928) Notes sur les protistes para- 
sites des termites de France. V. Arch. zool. exper. gen., 67 

(1928a) L'appareil parabasal de Joenia annectens. 

C. R. Soc. biol., 99:1118. 

(1943) Les flagelles de V Anacanthotermes ochraccus. 

Arch. zool. exper. gen., 82:401, 

and Rose, M.: (1937) La flagelle de V Anacantho- 

termes ochraceus du Sud-Algerien. C. R. Acad. Sc, 205:574. 
Grasse, P. P.: (1952) Traite de zoologie. I. Fasc. 1. Paris. 
and Hollande, A.: (1945) La structure d'une hypermasti- 

gine complexe Staurojoenina caulleryi. Ann. Sc. Nat. Bot. Zool., 

Grassi, B.: (1885) Intorno ad alcuni protozoi parassiti delle termiti. 

Atti Accad. Gioenia Sci. Nat, Catania, Ser. 3, 18:235. 

— (1892) Conclusioni d'una memoria sulla societa dei termiti. 

Atti R. Accad. Lincei, Ser. 5, 1:33. 


(1917) Flagellati viventi nei termiti. Mem. R. Accad. Lincei, 


and FoA, Anna: (1911) Intorno di protozoi dei termitidi. 

Atti R. Accad. Lincei, Ser. 5, 20:725. 

Hungate, R. E.: (1939) Experiments on the nutrition of Zooter- 
mopsis. III. Ecology, 20:230. 

Janicki, C: (1910) Untersuchungen an parasitischen Flagellaten. I. 
Ztschr. wiss. Zool., 95:245. 

(1915) II. Ibid., 112:573. 

Katzin, L. I. and Kirby, H. Jr.: (1939) The relative weights of ter- 
mites and their Protozoa. J. Parasit., 25:444. 

Kirby, H. Jr.: (1926) On Staurojoenina assimilis, etc. Univ. Cali- 
fornia Publ. Zool., 29:25. 

— — (1932) Flagellates of the genus Trichonympha. Ibid.,37:349. 

(1937) Host-parasite relations in the distribution of Protozoa 

in termites. Ibid., 41:189. 

(1944) The structural characteristics and nuclear parasites 

of some species of Trichonympha in termites. Ibid., 49: 185. 

Kofoid, C. A. and Swezy, Olive: (1919) Studies on the parasites of 
termites. III. Ibid., 20:41. 

(1919a) IV. Ibid., 20:99. 

Koidzumi, M.: (1917) Studies on the Protozoa harboured by the 
termites of Japan. Rep. Invest, on termites, 6:1. 

(1921) Studies on the intestinal Protozoa found in the ter- 
mites of Japan. Parasitology, 13:235. 

Kudo, R. R.: (1926) Observations on Lophomonas blattaram, etc. 
Arch. Protist., 53:191. 

(1926a) A cytological study of Lophomonas striata. Ibid., 55: 


Leidy, J.: (1877) On intestinal parasites of Termes flavipes. Proc. 
Acad. Nat. Sc. Philadelphia, p. 146. 

Light, S. F.: (1926) Hoplonympha natator. Univ. California Publ. 
Zool., 29:123. 

— (1927) Kofoidia, a new flagellate, from a California termite. 

Ibid., 29:467. 

and Sanford, Mary F.: (1928) Experimental transfaunation 

of termites. Ibid., 31:269. 
MacLennan, R. F. and Murer, H. K.: (1934) Localization of 

mineral ash in the organelles of Trichonympha, etc. J. Morphol., 

Sutherland, J. L.: (1933) Protozoa from Australian termites. Quart. 

J. Micr. Sc, 76:145. 
Swezy, Olive: (1923) The pseudopodial method of feeding by 

trichomonad flagellates parasitic in wood-eating termites. 

Univ. California Publ. Zool., 20:391. 

Chapter 17 
Class 2 Sarcodina Hertwig and Lesser 

THE members of this class do not possess any thick pellicle 
and, therefore, are capable of forming pseudopodia (p. 49). 
The term 'amoeboid' is often used to describe their appearance. 
The pseudopodia serve ordinarily for both locomotion and food- 
capturing. The peripheral portion of the body shows no structural 
differentiation in Amoebina, Proteomyxa, and Mycetozoa. Internal 
and external skeletal structures are variously developed in other 
orders. Thus, in Testacea and Foraminifera, there is a well-devel- 
oped test or shell that usually has an aperture, through which the 
pseudopodia are extruded; in Heliozoa and Radiolaria, skeletons of 
various forms and materials are developed. 

The cytoplasm is, as a rule, differentiated into the ectoplasm and 
the endoplasm, but this differentiation is not constant. In Radio- 
laria, there is a perforated membranous central capsule which marks 
the border line between the two cytoplasmic regions. The endoplasm 
contains the nucleus, food vacuoles and various granules. The ma- 
jority of Sarcodina are uninucleate, but species of Foraminifera and 
Mycetozoa are multinucleate in certain phases during their develop- 
ment. In the family Paramoebidae, there occurs a peculiar secondary 

The Sarcodina are typically holozoic. Their food organisms are 
Protozoa, small Metazoa and Protophyta, which present themselves 
conspicuously in the cytoplasm. The methods of ingestion have al- 
ready been considered (p. 97). One or more contractile vacuoles 
are invariably present in forms inhabiting the fresh water, but absent 
in parasitic forms or in those which live in the salt water. 

Asexual reproduction is usually by binary (or rarely multiple) 
fission, budding, or plasmotomy. Definite proof of sexual reproduc- 
tion has been noted in a comparatively small number of species. 
Encystment is common in the majority of Sarcodina, but is unknown 
in a few species. The life-cycle has been worked out in some forms 
and seems to vary among different groups. The young stages are 
either amoeboid or flagellate, and on this account, it is sometimes 
very difficult to distinguish the Sarcodina and the Mastigophora. 
In some forms the mature trophic stage may show an amoeboid or 
flagellate phase, owing to differences in environmental conditions. 

The Sarcodina are divided into two subclasses as follows : 

With lobopodia, rhizopodia, or filopodia . . Subclass 1 Rhizopoda (p. 418) 
With axopodia Subclass 2 Actinopoda (p. 505) 



Subclass 1 Rhizopoda Siebold 

The name Rhizopoda has often been used to designate the entire 
class, but it is used here for one of the subclasses, which is further 
subdivided into five orders, as follows: 

Without test or shell 

With radiating pseudopodia Order 1 Proteomyxa 

With rhizopodia; forming Plasmodium. . .Order 2 Mycetozoa (p. 427) 
With lobopodia Order 3 Amoebina (p. 435) 

With test or shell 

Test single-chambered; chitinous Order 4 Testacea (p. 472) 

Test 1- to many-chambered; calcareous . . Order 5 Foraminifera (p. 493) 

Order 1 Proteomyxa Lankester 

A number of incompletely known Rhizopods are placed in this 
group. The pseudopodia are filopodia which often branch or anas- 
tomose with one another. In this respect the Proteomyxa show 
affinity to the Mycetozoa. Flagellate swarmers and encystment occur 
commonly. The majority of Proteomyxa lead parasitic life in algae 
or higher plants in fresh or salt water. Taxonomy (Valkanov, 1940). 

Pseudoplasmodium-formation Family 1 Labyrinthulidae 

Solitary and Heliozoa-like 

With flagellate swarmers Family 2 Pseudosporidae (p. 420) 

Without flagellate swarmers Family 3 Vampyrellidae (p. 420) 

Family 1 Labyrinthulidae Haeckel 

Small fusiform protoplasmic masses are grouped in network of 
sparingly branched and anastomosing filopodia; individuals encyst 
independently; with or without flagellate stages. 

Genus Labyrinthula Cienkowski. Minute forms feeding on various 
species of algae in fresh or salt water; often brightly colored due to 
carotin. Jepps (1931) found these organisms common in marine 
aquaria. Young (1943) considers the six known species as actually 
three species and two varieties, while Watson (1951) holds that only 
one species, L. macrocystis, should be recognized. 

L. cienkowskii Zopf (Fig. 176, a). Attacks Vaucheria in fresh water. 

L. macrocystis Cienkowski. Renn (1934, 1936) found a species in 
the diseased leaf-tissue of the 'spotting and darkening' eel-grass, 
Zostera marina, along the Atlantic coast of the United States. Young 
(1943) identified the organism which he studied as L. macrocystis, 
and noted that its hosts included various algae and three genera of 
Naiadaceae: Zostera, Ruppia and Zannichellia. 

The 'net-plasmodium' contains fusiform cells which average in size 



18/x by 4/x and which multiply by binary fission; many cells encyst 
together within a tough, opaque membrane. The growth is best at 
14-24°C. and at 12-22 per cent chlorinity (Young). Watson and 
Ordal (1951) cultivated the organism on agar and sea water with 
various bacteria, and found that the organism is fusiform in young- 
cultures; highly motile; filamentous projections are formed from the 
flat mucoid lamellae, secreted by the organism, and expand to form 
passways over which the organism travels; holozoic, saprozoic. 

Genus Labyrinthomyxa Duboscq. Body fusiform; amoeboid and 
flagellate phases, variable in size; flagellate stage penetrates the host 
cell membrane; in plants. 

Fig. 176. a, Labyrinthula cienkowskii, X200 (Doflein); b-e, Laby- 
rinthomyxa sauvageaui (b, c, flagellate forms, XlOO; d, e, amoeboid 
forms, X500) (Duboscq); f, g, Pseudospora volvocis, X670 (Robert- 
son); h-j, Protonwnas amyli (Zopf);k, 1, Vampyrella lateritia, X530 
(k (Leidy), 1 (Doflein)); m, n, Nuclearia delicatula, X300 (Cash). 


L. sauvageaui D. (Fig. 176, b-e). Fusiform body 7— llyu long; pseu- 
doplasmodium-formation; amoeboid stage 2.5-14ju long; flagellate 
stage 7-18/z long; parasitic in Laminaria lejolisii at Roscoff, France. 

Family 2 Pseudosporidae Berlese 

Genus Pseudospora Cienkowski. Body minute; parasitic in algae 
and Mastigophora (including Volvocidae) ; organism nourishes itself 
on host protoplasm, grows and multiplies into a number of smaller 
individuals, by repeated division; the latter biflagellate, seek a new 
host, and transform themselves into amoeboid stage; encystment 
common. Morphology and development (Schussnig, 1929). 

P. volvocis C. (Fig. 176, /, g). Heliozoan form about 12-30/1 in 
diameter; pseudopodia radiating; cysts about 25ju in diameter; in 
species of Volvox. Morphology (Roskin, 1927). 

P. -parasitica C. Attacks Spirogyra and allied algae. 

P. eudorini Roskin. Heliozoan forms 10-12/x in diameter; radiating 
pseudopodia 2-3 times longer; amoeboid within host colony; cysts 
15 n in diameter; in Eudorina elegans. 

Genus Protomonas Cienkowski. Body irregularly rounded with 
radiating filo podia; food consists of starch grains; division into bi- 
flagellate organisms which become amoeboid and unite to form 
pseudo plasmodium; fresh or salt water. 

P. amyli C. (Fig. 176, h-j). In fresh water. 

Family 3 Vampyrellidae Doflein 

Filo podia radiate from all sides or formed from a limited area; 
flagellate forms do not occur; the organism is able to bore 
through the cellulose membrane of various algae and feeds on proto- 
plasmic contents; body often reddish because of the presence of 
carotin; multinucleate; multiplication in encysted stage into uni- or 
multi-nucleate bodies; cysts often also reddish. 

Genus Vampyrella Cienkowski. Heliozoa-like; endoplasm vacuo- 
lated or granulated, with carotin granules; numerous vesicular 
nuclei and contractile vacuoles; multinucleate cysts, sometimes 
with stalk; 50-700/* in diameter. Several species. 

V. lateritia (Fresenius) (Fig. 176, k, I). Spherical; orange-red 
except the hyaline ectoplasm; feeds on Spirogyra and other algae 
in fresh water. On coming in contact with an alga, it often travels 
along it and sometimes breaks it at joints, or pierces individual cell 
and extracts chlorophyll bodies by means of pseudopodia; multipli- 
cation in encysted condition; 30-40/z in diameter. Behavior (Lloyd, 
1926, 1929). 



Genus Nuclearia Cienkowski. Subspherical, with sharply pointed 
fine radiating pseudopodia; actively moving forms vary in shape; 
with or without a mucous envelope; with one or many nuclei; fresh 

Fig. 177. a, Arachnula impatiens, X670 (Dobell); b, c, Chalnwjdomyxa 
montana: b, X270 (Cash); c, X530 (Penard); d, Rhizoplasma kaiseri, 
(Verworn); e, Biomyxa vagans, X200 (Cash); f, Penardia mutabilis, X200 
(Cash); g, Hyalodiscus rubicundus, X370 (Penard). 


N. delicatula C. (Fig. 176, m, n). Multinucleate; bacteria often 
adhering to gelatinous envelope; up to 60m in diameter. 

N. simplex C. Uninucleate ; 30ju in diameter. 

Genus Arachnula Cienkowski. Body irregularly chain-form with 
filo podia extending from ends of branches; numerous nuclei and 
contractile vacuoles; feeds on diatoms and other microorganisms. 

A. impatiens C. (Fig. 177, a). 40-35Gy in diameter. 

Genus Chlamydomyxa Archer. Body spheroidal; ectoplasm and 
endoplasm well differentiated; endoplasm often green-colored due 
to the presence of green spherules; numerous vesicular nuclei; 1-2 
contractile vacuoles; secretion of an envelope around the body is 
followed by multiplication into numerous secondary cysts; cyst wall 
cellulose; in sphagnum swamp. 

C. montana Lankester (Fig. 177, b, c). Rounded or ovoid; cyto- 
plasm colored; about 50/* in diameter; when moving, elongate with 
extremely fine pseudo podia which are straight or slightly curved 
and which are capable of movement from side to side; non-con- 
tractile vacuoles at bases of grouped pseudo pods; in active individ- 
ual there is a constant movement of minute fusiform bodies 
(function?); when extended 100-150^ long; total length 300/x or 
more; fresh water among vegetation. 

Genus Rhizoplasma Verworn. Spherical or sausage-shaped; with 
anastomosing filo podia; orange-red; with a few nuclei. 

R. kaiseri V. (Fig. 177, d). Contracted form 0.5-1 mm. in diameter; 
with 1-3 nuclei; pseudo podia up to 3 cm. long; extended body up to 
10 mm. long; originally described from Red Sea. 

Genus Chondropus Greeff. Spherical to oval; peripheral portion 
transparent but often yellowish; endoplasm filled with green, yellow, 
brown bodies; neither nucleus nor contractile vacuoles observed; 
pseudo pods straight, fine, often branched; small pearl-like bodies on 
body surface and pseudopodia. 

C. viridis G. Average diameter 35-45^; fresh water among algae. 

Genus Biomyxa Leidy (Gymnophrys Cienkowski). Body form in- 
constant; initial form spherical; cytoplasm colorless, finely granu- 
lated, capable of expanding and extending in any direction, with 
many filopodia which freely branch and anastomose; cytoplasmic 
movement active throughout; numerous small contractile vacuoles 
in body and pseudopodia; with one or more nuclei. 

B. vagans L. (Fig. 177, e). Main part of body, of various forms; 
size varies greatly; in sphagnous swamps, bog-water, etc. 

B. cometa (C). Subspherical or irregularly ellipsoidal; pseudopodia 
small in number, formed from 2 or more points; body 35-40/z, or up 


to 80/x or more; pseudopodia 400/x long or longer. Cienkowski main- 
tained that this was a moneran. 

Genus Penardia Cash. When inactive, rounded or ovoid; at other 
times expanded; exceedingly mobile; endoplasm chlorophyll-green 
with a pale marginal zone; filopodia, branching and anastomosing, 
colorless; nucleus inconspicuous; one or more contractile vacuoles, 
small; fresh water. 

P. mutabilis C. (Fig. 177, /). Resting form 90-100/x in diameter; 
extended forms (including pseudopodia) 300-400/x long. 

Genus Hyalodiscus Hertwig and Lesser. Discoid, though outline 
varies; endoplasm reddish, often vacuolated and sometimes shows 
filamentous projections reaching body surface; a single nucleus; 
ectoplasmic band of varying width surrounds the body completely; 
closely allied to Vampyrella; fresh water. 

H. rubicundus H. and L. (Fig. 177, g). 50-80/x by about 30ju; 
polymorphic; when its progress during movement is interrupted by 
an object, the body doubles back upon itself, and moves on in 
some other direction; freshwater ponds among surface vegetation. 

Genus Leptomyxa Goodey. Multinucleate, thin, amoeboid or- 
ganisms; multinucleate cysts formed by condensation of protoplasm; 
free-living in soil (Goodey, 1915). 

L. reticulata G. (Fig. 178, a-c). Body composed of a thin trans- 
parent protoplasm; when fully extended, 3 mm. or more in length; 
superficially resembles an endosporous mycetozoan, but no reversi- 
ble cytoplasmic movement; multinucleate with eight to 20 to several 
hundred nuclei; nuclei, 5-6/z in diameter, with a large endosome; 
nuclear division simultaneous, but not synchronous; plasmotomy; 
plasmogamy; cysts multinucleate, by local condensation of proto- 
plasm; widely distributed in British soil (Singh, 1948, 1948a). 
McLennan (1930) found a similar organism in and on the root of 
diseased hops in Tasmania. 

Genus Megamoebomyxa Nyholm. Extremely large amoeboid or- 
ganism; when contracted, lobulate, with adhering detritus; when 
cultured at 8-10°C. on debris, filopodia are formed and form-change 
occurs; lobate during locomotion; "nutrient chiefly detritus"; Ma- 
rine. One species (Nyholm, 1950). 

M. argillobia N. (Fig. 178, d). An opaque white organism; up to 
25 mm. long; polymorphic; in marine sediment, rich in debris at the 
depth of 45-70 in.; Gullmar Fjord, Sweden. 

Genus Reticulomyxa Nauss. Highly polymorphic, multinucleate 
amoeboid organism; rhizopodia radiating from a central mass of un- 
differentiated granular protoplasm with many non-contractile vacu- 



Fig. 178. a-c, Leptomyxa reticulata, X73 (Singh) (a, a trophozoite; 
b, cyst-formation; c, a cyst); d, an individual of Megamoebomyxa argil- 
lobia, showing the changes of body form, X2/3 fNyholm); e, a young 
trophozoite of Reticulomyxa filosa, X3 (Nauss). 

oles; plasmotomy usually into three, after discarding extraneous 
particles and migrating to new site; when transferred to fresh dish of 
water, "spore-like" bodies are dispersed; fresh water among decaying 
leaves. Nauss (1949) points out its affinity to Proteomyxa, Myceto- 
zoa and Foraminifera. 

R. filosa N. (Fig. 178, e). On moist blotting paper the central mass 
is an elevated body, but in water it spreads into a broad sheet, 4-6 
mm. in diameter; pseudopodia may be up to 10 times the diameter 
of the central white mass; encyst ment occurs when subjected to 


lower temperature or when cultured with algae; food consists of 
"worms," rotifers and organic debris. 


Cash, J.: (1905,1909) The British freshwater Rhizopoda and 

Heliozoa. 1, 2. London. 

— and Wailes, G. H. : (1915-1918) 3, 4 London. 
Doflein, F. and Reichenow, E.: (1929) Lehrbuch der Protozoen- 

kunde. 5 ed. Jena. 
Kuhn, A.: (1926) Morphologie der Tiere in Bildern. H.2, T.2. 

Rhizopoden. Jena. 
Leidy, J.: (1879) Freshwater Rhizopods of North America. Rep. 

U. S. Geol. Survey, 12. 
Penard, E.: (1902) Faune rhizopodique du bassin du Leman. 


Cash, J.: (1905) The British freshwater Rhizopoda and Heliozoa. 1. 

Cienkowski, L.: (1863) Das Plasmodium. Pringsheim's Jahrb. Bot., 

(1867) Ueber den Bau und die Entwicklung der Labyrinthu- 

leen. Arch. mikr. Anat., 3:274. 

Dobell, C: (1913) Observations on the life-history of Cienkowski's 
Arachnula. Arch. Protist., 31:317. 

Duboscq, O.: (1921) Labyrinthomyxa sauvageaui, etc. C. R. Soc. 
bid., 84:27. 

Goodey, T.: (1915) A preliminary communication of three new pro- 
teomyxan rhizopods from soil. Arch. Protist., 35:80. 

Jepps, Margaret W.: (1931) Note on a marine Labyrinthula. J. 
Marine Biol. Ass. United Kingdom, 17:833. 

Lloyd, F. E.: (1926) Some behaviours of Vampyrella lateritia, etc. 
Papers Mich. Acad. Sc, 6:275. 

(1929) The behavior of Vampyrella lateritia, etc. Arch. Pro- 
tist., 67:219. 

McLennan, E. I.: (1930) A disease of hops in Tasmania and an ac- 
count of a proteomyxan organism, etc. Australian J. Exper. 
Biol., 7:9. 

Nauss, Ruth N.: (1949) Reticulomyxa filosa, etc. Bull. Torrey Bot. 
Club, 76:161. 

Nyholm, K.-G.: (1950) A marine nude rhizopod type Megamoebo- 
myxa argillobia. Zool. Bidrag. Uppsala, 29:93. 

Renn, C. E.: (1935) A mycetozoan parasite of Zostera marina. Na- 
ture, 135:544. 

(1936) The wasting disease of Zostera marina. Biol. Bull., 


Roskin, G.: (1927) Zur Kenntnis der Gattung Pseudospora. Arch. 
Protist., 59:350. 

Schussnig, B.: (1929) Beitrage zur Entwicklungsgeschichte der 
Protophyten. IV. Ibid., 68:555. 


Singh, B. N.: (1948) Studies on giant amoeboid organisms. I. J. Gen. 

Microbiol., 2:7. 

(1948a) II. Ibid., 2:89. 

Valkanov, A.: (1929) Protistenstudien. IV. Arch. Protist., 67:110. 

— (1940) Die Heliozoen und Proteomyxien. Ibid., 93:225. 
Watson, S. W. and Ordal, E. J.: (1951) Studies on Labyrinthula. 

Univ. Washington Oceanogr. Lab., Tech. Rep., 3, 37 pp. 
Young, E. L.: (1943) Studies on Labyrinthula, etc. Am. J. Bot., 30: 

Zopf, W.: (1887) Handbuch der Botanik (A. Schenk), 3:24. 

Chapter 18 
Order 2 Mycetozoa de Bary 

THE Mycetozoa had been considered to be closely related to the 
fungi, being known as Myxomycetes, or Myxogasteres, the 
'slime molds.' Through extended studies of their development, 
de Bary showed that they are more closely related to the Protozoa 
than to the Protophyta, although they stand undoubtedly on the 
border-line between these two groups of microorganisms. The Myce- 
tozoa occur on dead wood or decaying vegetable matter of various 

The most conspicuous part of a mycetozoan is its Plasmodium 
which is formed by fusion of many myxamoebae, thus producing 
a large multinucleate body (Fig. 179, a). The greater part of the 
cytoplasm is granulated, although there is a thin layer of hyaline and 
homogeneous cytoplasm surrounding the whole body. The numerous 
vesicular nuclei are distributed throughout the granular cytoplasm. 
Many small contractile vacuoles are present in the peripheral por- 
tion of the Plasmodium. The nuclei increase in number by division 
as the body grows; the division seems to be amitotic during the 
growth period of the Plasmodium, but is mitotic prior to the spore- 
formation. The granulation of the cytoplasm is due to the presence 
of enormous numbers of granules which in some forms are made up 
of carbonate of lime. The Plasmodium is usually colorless, but some- 
times yellow, green, or reddish, because of the numerous droplets of 
fluid pigment present in the cytoplasm. 

The food of Mycetozoa varies among different species. The great 
majority feed on decaying vegetable matter, but some, such as 
Badhamia, devour living fungi. Thus the Mycetozoa are holozoic or 
saprozoic in their mode of nutrition. Pepsin has been found in the 
Plasmodium of Fuligo and is perhaps secreted into the food vacuoles, 
into which protein materials are taken. The Plasmodium of Bad- 
hamia is said to possess the power of cellulose digestion. 

When exposed to unfavorable conditions, such as desiccation, 
the protoplasmic movement ceases gradually, foreign bodies are 
extruded, and the whole Plasmodium becomes divided into numer- 
ous sclerotia or cysts, each containing 10-20 nuclei and being sur- 
rounded by a resistant wall (6). These cysts may live as long as three 
years. Upon return of favorable conditions, the contents of the 
sclerotia germinate, fuse together, and thus again produce plasmodia 

When lack of food material occurs, the Plasmodium undergoes 




changes and develops sporangia. The first indication of this process 
is the appearance of lobular masses of protoplasm in various parts 
of the body (/, g). These masses are at first connected with the stream- 
ing protoplasmic thickenings, but later become completely segre- 
gated into young sporangia. During the course of sporangium-for- 
mation, foreign bodies are thrown out of the body, and around each 

Fig. 179. The life-cycle of the endosporous mycetozoan (de Bary, 
Lister, and others), a, plasmodium-formation by fusion of numerous 
myxamoebae; b, c, formation of sclerotium; d, e, germination of sclero- 
tium and formation of Plasmodium; f, portion of a Plasmodium showing 
streaming protoplasmic thickenings; g, h, formation of sporangia; i, a 
sporangium opened, showing capillitium; j, a spore; k, germination of 
spore; 1, myxamoeba; m, n, myxoflagellates; o-q, multiplication of 
myxoflagellate; r, microcyst; s, myxamoeba. Variously magnified. 

sporangium there is secreted a wall which, when mature, possesses a 
wrinkled appearance (h). The wall continues down to the substra- 
tum as a slender stalk of varying length, and in many genera the end 
of a stalk spreads into a network over the substratum, which forms 
the base, hypothallus, for the stalk. With these changes the interior 


of the sporangium becomes penetrated by an anastomosing network, 
capillitium, of flat bands which are continuous with the outer cover- 
ing (i). Soon after the differentiation of these protective and sup- 
porting structures, the nuclei divide simultaneously by mitosis and 
the cytoplasm breaks up into many small bodies. These uninucleate 
bodies are the spores which measure 3-20/x in diameter and which 
soon become covered by a more or less thick cellulose membrane (j), 
variously colored in different species. 

The mature sporangium breaks open sooner or later and the 
spores are carried, and scattered, by the wind. When a spore falls 
in water, its membrane ruptures, and the protoplasmic contents 
emerge as an amoebula (k, I). The amoebula possesses a single vesic- 
ular nucleus and contractile vacuoles, and undergoes a typical amoe- 
boid movement. It presently assumes an elongate form and one 
flagellum or two unequally long flagella (Elliott, 1948) develop from 
the nucleated end, thus forming a myxoflagellate (m, n) which under- 
goes a peculiar dancing movement and is able to form short, pointed 
pseudopodia from the posterior end. It feeds on bacteria, grows and 
multiplies by binary fission (o-q). After a series of division, the myxo- 
flagellate may encyst and becomes a microcyst (r). When the micro- 
cyst germinates, the content develops into a myxamoeba (s) which, 
through fusion with many others, produces the Plasmodium men- 
tioned above. This is the life-cycle of a typical endosporous myceto- 

In the genus Ceratiomyxa in which spores are formed on the sur- 
face of sporophores, the development is briefly as follows: the 
Plasmodium lives on or in decayed wood and presents a horn-like 
appearance. The body is covered by a gelatinous hyaline substance, 
within which the protoplasmic movements may be noted. The proto- 
plasm soon leaves the interior and accumulates at the surf ace of the 
mass; at first as a close-set reticulum and then into a mosaic of 
polygonal cells, each containing a single nucleus. Each of these cells 
moves outward at right angles to the surface, still enveloped by the 
thin hyaline layer, which forms a stalk below. These cells are spores 
which become ellipsoid and covered by a membrane when fully 
formed. The spore is uninucleate at first, but soon becomes tetranu- 
cleate. When a spore reaches the water, its content emerges as an 
amoebula which divides three times, forming 8 small bodies, each 
of which develops a flagellum and becomes a myxoflagellate. The 
remaining part of the development is presumably similar to that of 
the endosporous form. Morphology (de Bary, 1864, 1884; MacBride, 
1922; Jahn, 1928; MacBride and Martin, 1934). 


A large number of mycetozoan genera and species are known 
(Hagelstein, 1944). The order is divided here into two suborders. 

Spore develops into myxoflagellate; myxamoebae fuse completely and 
form Plasmodium Suborder 1 Eumycetozoa 

No flagellate stage; myxamoebae grouped prior to spore-formation, but 

do not fuse to form a true Plasmodium 

Suborder 2 Sorophora (p. 433) 

Suborder 1 Eumycetozoa Zopf 

Spores develop within sporangia 
Spores violet or violet-brown 
Sporangia with lime 

Lime in small granular form Family 1 Physaridae 

Fig. 180. a, b, Badhamia utricularis Berkeley (a, cluster of sporangia, 
X4; b, part of capillitium and spore-cluster, X140) (Lister); c, d, Fuligo 
septica Gmelin (c, a group of sporangia, X^; d, part of capillitium and 
two spores, X120) (Lister); e, f, Didymium effusum Link (e, sporan- 
gium, Xl2; f, portion of capillitium and wall of sporangium showing 
the crystals of calcium carbonate and two spores, X200) (Lister); 
g, h, Stemonitis splendens Rostafinski (g, three sporangia, X2; h, col- 
umella and capillitium, X42) (Lister). 

Genus Badhamia Berkeley (Fig. 180, a, b) 
Capillitium, a course network with lime throughout. 

Genus Fuligo Haller (Fig. 180, c, d) 

Capillitium, a delicate network of threads with vesicular expan- 
sions filled with granules of lime. 

Lime in crystalline form Family 2 Didymiidae 


Genus Didymium Schrader (Fig. 180, e, f) 

Lime crystals stellate, distributed over the wall of sporangium. 
Sporangia without lime 

Sporangia stalked Family 3 Stemonitidae 

Genus Stemonitis Gleditsch (Fig. 180, g, h) 

Sporangium-wall evanescent; capillitium arising from all parts of 
columella to form a network. 

Sporangium combined into aethalium 

Family 4 Amaurochaetidae 

Genus Amaurochaete Rostafinski (Fig. 181, a, b) 

With irregularly branching thread-like capillitium. 
Spores variously colored, except violet 

Capillitium absent or not forming a system of uniform threads. 

Sporangium-wall membranous; with minute round granules 

Family 5 Cribrariidae 

c^ggfc, d . 

W$9 f?m 

Fig. 181. a, b, Amaurochaete fuliginosa MacBride (a, group of spor- 
angia, X£; b, capillitium, XlO) (Lister); c, empty sporangium of Cri- 
braria aurantiaca Schrader, X20 (Lister); d, sporangium of Orcadella 
operculata Wingate, X80 (Lister); e, cluster of sporangia of Tubulina 
fragiformis Persoon, X3 (Lister); f, aethalium of Reticularia lycoperdon 
Bull., XI (Lister); g, aethalium of Lycogala miniatum Persoon Xl (Lis- 
ter); h-j, Trichia affinis de Bary (h, group of sporangia, X2; i, elater, 
X250; j, spore, X400) (Lister); k, 1, Arcyria punicea Persoon (k, four 
sporangia, X2; 1, part of capillitium, X 250 and a spore, X 560) (Lister); 
m, n, Ceratiomyxa fruticulosa MacBride (m, sporophore, X40; n, part of 
mature sporophore, showing two spores, X480) (Lister). 


Genus Cribraria Persoon (Fig. 181, c) 

Sporangia stalked; wall thickened and forms a delicate persistent 
network expanded at the nodes. 

Sporangia solitary; stalked Family 6 Liceidae 

Genus Orcadella Wingate (Fig. 181, d) 
Sporangia stalked, furnished with a lid of thinner substance. 

Sporangium-wall membranous without granular deposits 

Family 7 Tubulinidae 

Genus Tubulina Persoon (Fig. 181, e) 

Sporangia without tubular extensions. 

Many sporangia more or less closely fused to form large bodies 

(aethalia); sporangium-wall incomplete and perforated 

Family 8 Reticulariidae 

Genus Reticularia Bulliard (Fig. 181,/) 

Walls of convoluted sporangia incomplete, forming tubes and folds 
with numerous anastomosing threads. 

Sporangia forming aethalium Family 9 Lycogalidae 

Genus Lycogala Micheli (Fig. 181, g) 

Oapillitium a system of uniform threads 

Capillitium threads with spiral or annular thickenings 

Family 10 Trichiidae 

Genus Trichia Haller (Fig. 181, h-j) 

Capillitium abundant, consisting of free elasters with spiral 

Capillitium combined into an elastic network with thickenings in 
forms of cogs, half-rings, spines, or warts. Family 11 Arcyriidae 

Genus Arcyria Wiggers (Fig. 181, A;, I) 

Sporangia stalked; sporangium-wall evanescent above, persistent 
and membranous in the lower third. 

Capillitium abundant; sporangia normally sessile 

Family 12 Margaritidae 

Genus Margarita Lister 

Capillitium profuse, long, coiled hair-like. 

Spores develop on the surface of sporophores 

Spores white; borne singly on filiform stalk 

Family 13 Ceratiomyxidae 


Genus Ceratiomyxa Schroter (Fig. 181, m, n) 
Suborder 2 Sorophora Lister 

Pseudoplasmodium incomplete; myxamoeba of limax-form 

Family 1 Guttuliniidae 

Pseudoplasmodium complete; myxamoeba with short pointed pseudo- 
podia Family 2 Dictyosteliidae 

The Proteomyxa and the Mycetozoa as outlined above, are not 
distinctly defined groups. In reality, there are a number of forms 
which stand on the border line between them. Development of 
Dictyostelium discoideum (Raper, 1940) ; food habits and distribution 
of Dictyostelium (Singh, 1947, 1947a). 

Phytomyxinea Poche 

These organisms which possess a large multinucleate amoeboid 
body, are parasitic in various plants and also in a few animals. Tax- 
onomy (Palm and Burk, 1933; Cook, 1933). 

Genus Plasmodiophora Woronin. Parasitic in the roots of cabbage 
and other cruciferous plants. The organism produces knotty enlarge- 
ments, sometimes known as "root-hernia," or "fingers and toes" 
(Fig. 182, a). The small (haploid) spore (6) gives rise to a myxoflagel- 
late (c-f) which penetrates the host cell. The organism grows in size 



Fig. 182. Plasmodiophora brassicae. a, root-hernia of cabbage; b, a 
spore, X620; c-e, stages in germination of spore, X620; f, myxamoeba, 
X620 (Woronin); g, a host cell with several young parasites, X400; 
h, an older parasite, X400 (Nawaschin). 

and multiplies (g, h). The Plasmodium divides into sporangia. Flagel- 
lated gametes that develop from them fuse in pairs, giving rise to 
diploid zygotes. These zygotes develop further into plasmodia in 
which haploid spores are produced. Morphology (Jones, 1928) ; cy- 
tology (Milovidov, 1931). 

P. brassicae W. (Fig. 182). In Brassica spp. 


Genus Sorosphaera Schroter. Parasitic in Veronica spp. 

Genus Tetramyxa Goebel. In Ruppia, Zannichellia, etc. 

Genus Octomyxa Couch, Leitner and Whiffen. In Achlya glomerata. 

Genus Sorodiscus Lagerheim and Winge. In Chara, Callitriche, etc. 

Genus Polymyxa Ledingham. In Triticum, etc. 

Genus Membranosorus Ostenfeld and Petersen. In Heteranthera 

Genus Spongospora Brunchorst. Parasitic in Solanum; the dis- 
eased condition of potatoes is known as powdery or corky scab. 

Genus Ligniera Maire and Tison. In Alisma, Juncus, etc. 


Cook, W. R. I.: (1933) A monograph of the Plasmodiophorales. 
Arch. Protist., 80:179. 

de Bary, A.: (1864) Die Mycetozoa. Leipzig. 

(1884) Vergleichende Morphologie und Biologie der Pilze, 

Mycetozoen, und Bacterien. Leipzig. 

Elliott, E. W.: (1948) The sperm-cells of Myxomycetes. J. Wash- 
ington Acad. Sc, 38:133. 

Hagelstein, R.: (1944) The Mycetozoa of North America. New 

Jahn, E.: (1901-1920) Myxomycetenstudien. I-X. Ber. deutsch. 
bot. Ges., 19, 20, 22-26, 29, 36 and 37. 

- (1928) Myxomycetenstudien. XII. Ibid., p. 80. 

Jones, P. M.: (1928) Morphology and cultural study of Plasmodio- 

phora brassicae. Arch. Protist., 62:313. 
Karling, J. S.: (1942) The Plasmodiophorales. New York. 
Lister, A.: (1925) A monograph on the Mycetozoa. 3 ed. London. 
MacBride, T. H.: (1922) North American slime molds. 2 ed. New 


— and Martin, G. H.: (1934) The Myxomycetes. New York. 
Milovidov, P. F.: (1931) Cytologische Untersuchungen an Plasmo- 

diophora brassicae. Arch. Protist., 73:1. 

Palm, B. T. and Burk, Myrle: (1933) The taxonomy of the Plas- 
modiophoraceae. Ibid., 79:262. 

Raper, K. B.: (1940) Pseudoplasmodium formation and organiza- 
tion in Dictyostelium discoideum. J. Elisha Mitchell Sc. Soc, 

Singh, B. N.: (1947) Studies on soilAcrasieae. I. J. Gen. Microbiol., 

(1947a) II. Ibid., 1:361. 

Chapter 19 
Order 3 Amoebina Ehrenberg 

THE Amoebina show a very little cortical differentiation. There 
is no thick pellicle or test, surrounding the body, although in 
some a delicate pellicle occurs. The cytoplasm is more or less dis- 
tinctly differentiated into the ectoplasm and the endoplasm. The ec- 
toplasm is hyaline and homogeneous, and appears tougher than the 
endoplasm. In the endoplasm, which is granulated or vacuolated, are 
found one or more nuclei, various food vacuoles, crystals, and other 
inclusions. In the freshwater forms, there is at least one distinctly 
visible contractile vacuole. The pseudopodia are lobopodia, and ordi- 
narily both the ectoplasm and endoplasm are found in them. They 
are formed by streaming or fountain movement of the cytoplasm. In 
some members of this order, the formation of pseudopodia is erup- 
tive or explosive, since the granules present in the endoplasm break 
through the border line between the two cytoplasmic layers and 
suddenly flow into the pseudopodia. Asexual reproduction is ordi- 
narily by binary fission, although multiple fission may occasionally 
take place. Encystment is of common occurrence. Sexual reproduc- 
tion, which has been reported in a few species, has not been con- 

The Amoebina inhabit all sorts of fresh, brackish, and salt waters. 
They are also found in moist soil and on ground covered with decay- 
ing leaves. Many are inhabitants of the digestive tract of various 
animals, and some are pathogenic to the hosts. 

The taxonomic status of the group is highly uncertain and con- 
fusing, since their life-histories are mostly unknown and since numer- 
ous protozoans other than the members of this group often possess 
amoeboid stages. 

The order is subdivided into four families as follows: 

With amoeboid and flagellate stages 

Family 1 Naegleriidae 

Amoeboid stage only 

With one or more nuclei of one kind 

Free-living Family 2 Amoebidae (p. 437) 

Parasitic Family 3 Endamoebidae (p. 443) 

With a secondary nucleus Family 4 Paramoebidae (p. 405) 

Family 1 Naegleriidae 

The members of the two genera placed in this family possess both 
amoeboid and flagellate phases [diphasic). In the former, the organ- 




ism undergoes amoeboid movement by means of lobopodia and in 
the latter the body is more or less elongated. Binary fission seems to 
take place during the amoeboid phase only. Thus these are diphasic 
amoebae, in which the amoeboid stage predominates over the 
flagellate. The amoeboid phase is often a 'limax' form; under natural 
circumstances, it is often exceedingly difficult by observing the 
amoeboid stage only, to determine whether they belong to this fam- 
ily or the family Amoebidae. 

Genus Naegleria Alexeieff. Minute flagellate stage with 2 flagella; 
amoeboid stage resembles Vahlkampfia (p. 442), with lobopodia; cy- 
toplasm differentiated; vesicular nucleus with a large endosome; 
contractile vacuole conspicuous; food vacuoles contain bacteria; 
cysts uninucleate; free-living in stagnant water and often coprozoic. 
Taxonomy and cytology (Rafalko, 1947; Singh, 1952). 

Fig. 183. a-c, trophozoite, flagellate phase and cyst Call stained) of 
Naegleria gruberi, X750 (Alexeieff); d-f, similar stages of N. bistadialis, 
X750 (Kiihn); g-j, trophozoite, flagellate phase, cyst, and excystment of 
Trimastigamoeba philippinensis, X950 (Whitmore). 

N. gruberi (Schardinger) (Fig. 183, a-c). Amoeboid stage 10 36jtt 
by 8-18/*; cyst uninucleate; cyst wall with several apertures; flagel- 
late stage 18/x by 8/t; stagnant water and often coprozoic. 

N. bistadialis (Puschkarew) (Fig. 183, d-f). Similar in size; but 
cyst with a smooth wall. 

Genus Trimastigamoeba Whitmore. Flagellate stage bears 3 
flagella of nearly equal length ; vesicular nucleus with a large endo- 
some; amoeboid stage small, less than 20/x in diameter; uninucleate 
cysts with smooth wall ; stagnant water. 

T. philippinensis W. (Fig. 183, g-j). Amoeboid stage 16-18/x in 
diameter; oval cysts 13-14/x by 8-12/t; flagellate stage 16-22/t by 


Family 2 Amoebidae Bronn 

These amoebae do not have flagellate stage and are exclusively 
amoeboid (monophasic) . They are free-living in fresh or salt water, 
in damp soil, moss, etc., and a few parasitic; 1, 2, or many nuclei; 
contractile vacuoles in freshwater forms; multiplication by binary 
or multiple fission or plasmotomy: encystment common. Genera 
(Leidy, 1879; Penard, 1902; Singh, 1952). 

Genus Amoeba Ehrenberg (Proteus Miiller; Amiba Bory). Amoe- 
boid; a vesicular nucleus, either with many spherical granules or with 
a conspicuous endosome; usually one contractile vacuole; pseudo- 
podia are lobopodia, never anastomosing with one another; holozoic; 
in fresh, brackish or salt water. Numerous species. Nomenclature 
(SchaefTer, 1926; Mast and Johnson, 1931; Kudo, 1952). 

A. proteus (Pallas) (Figs. 2, e, f; 25; 33, b, c; 43,/; 45-47; 68; 184, 
a, b). Up to 600m or longer in largest diameter; creeping with a few 
large lobopodia, showing longitudinal ridges; ectoplasm and endo- 
plasm usually distinctly differentiated; typically uninucleate; nu- 
cleus discoidal but polymorphic; endoplasmic crystals truncate bi- 
pyramid, up to 4.5m long (SchaefTer, 1916); nuclear and cytosomic 
divisions show a distinct correlation (p. 169); fresh water. Cytology 
(Mast, 1926; Mast and Doyle, 1935, 1935a) ; nuclear division (Chalk- 
ley, 1936; Liesche, 1938). 

A. discoides SchaefTer (Figs. 43, g; 184, c). About 400m long during 
locomotion; a few blunt, smooth pseudo podia; crystals abundant, 
truncate bipyramidal, about 2.5m long (SchaefTer) ; endoplasm with 
numerous coarse granules; fresh water. 

A. dubia S. (Figs. 43, h-l; 184, d). About 400m long; numerous 
pseudo podia flattened and with smooth surface; crystals, few, 
large, up to 30m long and of various forms among which at least 4 
types are said to be distinct (SchaefTer); contractile vacuole one or 
more; fresh water. Nuclear division (Dawson et al., 1935); viscosity 
(Angerer, 1942); contractile vacuole (Dawson, 1945). 

A. verrucosa Ehrenberg (Figs. 33, a, d-h; 44, a; 184, e). Ovoid in 
general outline with wart-like expansions; body surface usually 
wrinkled, with a definite pellicle; pseud opodia short, broad and 
blunt, very slowly formed; nucleus ovoid, vesicular, with a large en- 
dosome; contractile vacuole; up to 200m in diameter; fresh water 
among algae. 

A. striata Penard (Fig. 184,/). Somewhat similar to A. verrucosa, 
but small; body flattened; ovoid, narrowed and rounded posteriorly; 
nucleus vesicular; contractile vacuole comparatively large and often 



not spherical; extremely delicate pellicle shows 3 or 4 fine longitud- 
inal lines which appear and disappear with the movement of the 
body; 25-45/z by 20-35ju; fresh water among vegetation. 

Fig. 184. a, b, Amoeba proteus (a, X130 (Schaeffer), b, cyst (Doflein)); 
c, A. discoides, X130 (Schaeffer); d, A. dubia, X130 (Schaeffer); e, A. 
verrucosa, X200 (Cash); f, A. striata, X400 (Penard); g, A. guttula, 
X800 (Penard); h, A. limicola, X530 (Penard). 

A. guttula Dujardin (Fig. 184, g). Ovoid during locomotion, nar- 
rowed posteriorly and often with a few minute, nipple-like denta- 
tions; movement by wave-like expansions of ectoplasm; endoplasm 
granulated, with crystals; nucleus vesicular; a single contractile vac- 
uole; 30-35/z by 20-25)u; fresh water in vegetation. 

A. limicola Rhumbler (Fig. 184, h). Somewhat similar to A. gut- 


tula; body more rounded; locomotion by eruption of cytoplasm 
through the body surface; 45-55/z by 35/x; nucleus vesicular; fresh 
water among vegetation. 

Fig. 185. a, Amoeba spumosa, X400 (Penard); b, c, A. vespertilio, 
X300 (Penard); d-f, A. gorgonia, X400 (Penard); g, A. radiosa, X500 
(Penard); h, Dinamoeba mirabilis, X250 (Leidy). 

A. spumosa Gruber (Fig. 2, c, d; 185, a). Somewhat fan-shaped; 
flattened; during locomotion broad pseudopodia with pointed end; 
temporary posterior region with nipple-like projections; a small 


number of striae become visible during movement, showing there 
is a very thin pellicle; endoplasm always vacuolated, the vacuoles 
varying in size (up to 30m in diameter); vesicular nucleus with an 
endosome; 50-125/1 long during locomotion; fresh water. 

A. vespertilio Penard (Fig. 185, b, c.) Pseudo podia conical, com- 
paratively short, connected at base by web-like expansions of ecto- 
plasm; endoplasm colorless, with numerous granules and food par- 
ticles; a single vesicular nucleus with a large endosome; contractile 
vacuoles; 60-100/x long; fresh water. Cannibalism (Lapage, 1922); 
contractile vacuole (Hyman, 1936) ; morphology and biology (Raabe, 

A. gorgonia P. (Fig. 185, d-f). Body globular when inactive with 
a variable number of radiating "arms," formed on all sides; when 
in locomotion, clavate; nucleus vesicular, with a large endosome; 
rounded forms 40-50m in diameter; clavate individuals up to 100m; 
fresh water among vegetation. 

A. radiosa Ehrenberg (Fig. 185, g). Small, usually inactive; 
globular or oval in outline; with 3-10 radiating slender pseudo podia 
which vary in length and degree of rigidity; when pseudo pods are 
withdrawn, the organism may be similar to A. proieus in general ap- 
pearance; pseudo pods straight, curved or spirally coiled; size varies, 
usually about 30m in diameter, up to 120m or more: fresh water. 

Genus Dinamoeba Leidy. Essentially Amoeba, but the temporary 
posterior region of body with retractile papillae ; body surface includ- 
ing pseudopods and papillae, bristling with minute spicules or mo- 
tionless cils; often surrounded by a thick layer of delicate hyaline 
jelly, even during locomotion; fresh water. 

D. mirabilis L. (Fig. 185, h). Oval to limaciform; spheroid when 
floating; pseudo podia numerous, conical; ectoplasm clear, usually 
with cils; endoplasm with food vacuoles, oil (?) spherules and large 
clear globules; nucleus and contractile vacuole obscure; spherical 
forms 64-160m in diameter; creeping forms 152-340/x by 60-220m; 
cyst about 160m in diameter (Groot, 1936); in sphagnous swamp. 

Genus Pelomyxa Greeff. Large amoeboid organisms, ranging from 
0.5 to 4 or 5 mm. in length when clavate and moving progressively; 
nuclei numerous, less than 100 to 1000 or more; many small contrac- 
tile vacuoles; refringent bodies ("Glanzkorper") of various dimen- 
sion and number; with or without bacterial inclusions (which Penard 
and others consider as symbiotic); holozoic on plant or animal or- 
ganisms or detritus; plasmotomy simple or multiple; in fresh water. 
Several species (Kudo, 1946). Nomenclature (Schaeffer, 1926; Mast 
and Johnson, 1931; Rice, 1945; Kudo, 1946, 1952; Wilber, 1947). 



P. palustris G. (P. villosa Leidy) (Fig. 186, a). Large; 2-3 mm. or 
larger in diameter; sluggish, with usually one broad pseudopodium; 
undifferentiated cytoplasm with many nuclei and various inclusions 
such as fragments of plant bodies, numerous small sand particles, 
etc., which brings about opacity and dark coloration of body; in 
addition bacteria (Cladothrix pelomyxae Veley, Myxococcus pelomyxae 
Keller and Bacterium parapelomyxae Keller) occur in the cytoplasm 

Fig. 186. a, Pelomyxa palustris, X160 (Leidy); b, c, P. carolinensis, 
X45 (Kudo) (b, an individual in locomotion; c, feeding form); d, e, 
P. illinoisensis, X40 (Kudo) (d, an individual in locomotion; e, a more 
or less stationary animal); f, Vahlkampfia patuxent, X660 (Hogue); g, h, 
Acanthamoeba castellanii, X1270 (Hewitt); i, j, A. hyalina, X840 (Do- 

which some observers consider as symbionts; cyst with two to three 
envelopes (Stole, see Kudo, 1951) ; feeds on plant and inorganic de- 
bris; polysaprobic in still stagnant water, buried in mud. Central 
Europe, Great Britain and North America. Morphology (Greeff, 
1874; Hollande, 1945); locomotion (Okada, 1930a; Mast, 1934); 
plasmogamy (Okada, 1930) ; laboratory cultivation (Hollande, 1945). 


P. carolinensis Wilson (Figs. 66; 71; 186, b, c). Monopodal forms 
1-5 mm. long; polypodal forms 1-2 mm. in diameter; locomotion ac- 
tive; nuclei up to 1000 or more, circular in front view, about 20/x in 
diameter and ellipsoid in profile; fluid and food vacuoles, crystals, 
many contractile vacuoles; feeds on various Protozoa and inverte- 
brates; easily cultivated in laboratory; plasmotomy into two to six 
individuals; nuclear division simultaneous and synchronous; ex- 
perimental plasmogamy; no encystment in the Illinois stock, but 
New Jersey stock is said to encyst (Musacchia, 1950); North Amer- 
ica. Distribution (Kudo, 1946); morphology (Wilson, 1900; Andre- 
sen, 1942; Kudo, 1946); plasmotomy (Schaeffer, 1938; Kudo, 1949); 
nuclear division (Kudo, 1947); locomotion (Wilber, 1946); permea- 
bility (Belda, 1942-1943); effect of x-irradiation (Daniels, 1951, 
1952, 1952a). 

P. illinoisensis Kudo (Fig. 186, d, e). The organism resembles the 
last-named species, but much smaller in size; 500-1000 // in length; 
clavate forms seldom exceed 1.5 mm.; several hundred nuclei, spheri- 
cal, 14-16/z in diameter; peripheral granules of the nuclei are large 
and often discoid, irregularly distributed; crystals occur abundantly 
in all physiological conditions; chalky white in reflected light; plas- 
motomy into two to five daughters; encystment and excystment take 
place freely in cultures; cysts measure 250-350^ in diameter with 
usually two membranes, a multinucleate amoeba emerges from a 
cyst after several weeks (Kudo, 1950, 1951). Other species of Pelo- 
myxa (Kudo, 1951). 

Genus Vahlkampfia Chatton and Lalung-Bonnaire. Small amoe- 
bae; vesicular nucleus with a large endosome and peripheral chro- 
matin; with polar caps during nuclear division; snail-like movement, 
with one broad pseudo podium; cysts with a perforated wall; fresh 
water or parasitic. Nuclear division (Jollos, 1917). 

V. Umax (Dujardin). 30-40/x long; fresh water. 

V. patuxent Hogue (Fig. 186, /). In the alimentary canal of the 
oyster; about 20^ long during the first few days of artificial culti- 
vation, but later reaching as long as 140/* in diameter; ordinarily 
one large broad fan-shaped pseudopodium composed of the ecto- 
plasm; in culture, pseudopodium-formation eruptive; holozoic on 
bacteria; multiplication by fission or budding; encystment rare; 
cysts uninucleate. 

Genus Hartmannella Alexeieff. Small amoebae, with moderately 
or well-developed ectoplasm; vesicular nucleus with a large endo- 
some; mitotic figure ellipsoidal or cylindrical, without polar caps. 
Cysts rounded; wall smooth or slightly wrinkled in one species. 


Several species. Volkonsky (1933) distinguishes four groups. Species 
and morphology (Singh, 1952); nuclear division (Jollos, 1917). 

H. hyalina (Dangeard). 20-25/z in diameter; ectoplasm well 
developed; endoplasm vacuolated; slender pseudo podia extend in 
different directions; Hartmann and Chagas observed a centriole in 
the endosome. 

Genus Acanthamoeba Volkonsky. Small amoebae similar to Hart- 
mannella; ectoplasm is not well developed; mitotic figure at the end 
of metaphase, a straight or concave spindle with sharply pointed 
poles. Cysts enveloped by two membranes, the outer envelope being 
highly wrinkled and mammillated. Several species. 

A. castellanii (Douglas) (Fig. 186, g, h). In association with fungi 
and certain bacteria; Hewitt obtained the organism from agar cul- 
tures of sample soil taken from among the roots of white clover; co- 
existing with yeast-like fungi, Flavobacterium trifolium and Rhizo- 
bium sp.; 12-30/x in diameter; some cysts are said to remain viable 
at 37°C. for 6 days. 

A. hyalina (Dobell and O'Connor) (Fig. 186, *, j). According to 
Volkonsky, the organism described by Dobell and O'Connor as 
Hartmannella hyalina, is transferred to this genus. Small amoeba; 
9-17yu in diameter when rounded; a single contractile vacuole; binary 
fission; mitotic figure a sharply pointed spindle. Cysts spherical; 
10-15/x in diameter; with a smooth inner and a much wrinkled outer 
wall; easily cultivated from old faeces of man and animals; also in 
soil and fresh water. 

Genus Sappinia Dangeard. With two closely associated nuclei. 

S. diploidea (Hartmann and Nagler). Coprozoic in the faeces of 
different animals; pseudopodia short, broad, and few; highly vacu- 
olated endoplasm with 2 nuclei, food vacuoles, and a contractile 
vacuole; surface sometimes wrinkled; the nuclei divide simultane- 
ously; during encystment, two individuals come together and secrete 
a common cyst wall; 2 nuclei fuse so that each individual possesses 
a single nucleus; finally cytoplasmic masses unite into one; each 
nucleus gives off reduction bodies (?) which degenerate; 2 nuclei 
now come in contact without fusion, thus producing a binucleate 
cyst (Hartmann and Nagler). 

Family 3 Endamoebidae Calkins 

Exclusively parasitic amoebae; the vegetative form is relatively 
small and occurs mostly in the alimentary canal of the hosts; con- 
tractile vacuoles absent, except in Hydramoeba; multiplication by 
binary fission; encystment common. The generic differentiation is 



based upon the morphological characteristics of the nucleus. Sum- 
mary No. 99 of 'Opinions Rendered' by the International Commis- 
sion of Zoological Nomenclature (1928) holds that Entamoeba is a 
synonym of Endamoeba; in the present work, however, Endamoeba 
and Entamoeba are separated, since the two groups of species placed 
under them possess different nuclear characteristics (Fig. 187). No- 
menclature (Dobell, 1919, 1938; Kirby, 1945; Hemming, 1951). 

Genus Endamoeba Leidy (1879). Nucleus spheroidal to ovoid; 
membrane thick; in life, filled with numerous granules of uniform di- 
mensions along its peripheral region; upon fixation, a fine chro- 
matic network becomes noticeable in their stead; central portion 


Fig. 187. Diagram showing the stained nuclei of the trophozoites of 
five genera of parasitic amoebae, a, Endamoeba; b, Entamoeba; c, Ioda- 
moeba; d, Endolimax; e, Dientamoeba. 

coarsely reticulated ; with several endosomes between the two zones 
(Fig. 187, a) ; in some, cytoplasm becomes prominently striated dur- 
ing locomotion; in the intestine of invertebrates. 

E. blattae (Biitschli) (Fig. 188). In the colon of cockroaches; 10- 
150 n in diameter; rounded individuals with broad pseudopodia, show 
a distinct differentiation of cytoplasm; elongated forms with a few 
pseudopodia, show ectoplasm only at the extremities of the pseudo- 
pods; endoplasm of actively motile trophozoites shows a distinct 
striation, a condition not seen in other amoebae; fluid-filled vacuoles 
occur in large numbers; amoebae feed on starch grains, yeast cells, 
and bacteria, all of which coexist in the host organ; cysts, 20-50m 
in diameter, commonly seen in the colon contents, with often more 
than 60 nuclei. The life-cycle of this amoeba is still unknown. Mer- 
rier (1909) held that when the multinucleate cysts gain entrance to 
the host intestine through its mouth, each of the cyst-nuclei becomes 
the center of a gamete; when the cyst-membrane ruptures, the 
gametes are set free and anisogamy takes place, resulting in forma- 



tion of numerous zygotes which develop into the habitual tropho- 
zoites. Morphology (Leidy, 1879; Kudo, 1926; Morris, 1936; Meg- 
litsch, 1940). 

E. thomsoni Lucas. In the colon of cockroaches; 7-30/x in diameter; 
very adhesive; 1-3 large peripheral granules on the nuclear mem- 
brane; cysts 8-16ju in diameter, with 1-4 nuclei (Lucas, 1927). 

E. disparata Kirby. In colon of Microtermes hispaniolae ; 20-40^ 
long; active; xylophagous (Kirby, 1927). 

Fig. 188. Endamoeba blattae. a-c, trophozoites in life, X530; d, a stained 
binucleate amoeba; e, f, stained and fresh cysts, X700 (Kudo). 

E. majestas K. (Fig. 189, a). In the same habitat; 65-165ju in 
diameter; many short pseudo podia; cytoplasm rilled with food 
particles (Kirby, 1927). 

E. simulans K. (Fig. 189, b). In the gut of Microtermes pana- 
maensis; 50-1 50/z in diameter. 

E. sabulosa K. In the same habitat; small 19-35/z in diameter. 

E. pellucida, E. granosa, E. lutea and E. suggrandis were described 
from the colon of Cubitermes sp. of Africa (Henderson, 1941). 



Genus Entamoeba Casagrandi and Barbagallo (1895). Nucleus 
vesicular, with a comparatively small endosome, located in or near 
the center and with varying number of peripheral nonchromatinic 
granules attached to the nuclear membrane (Fig. 187, b) ; chromatin 
in the endosome and in peri-endosomal region. The genus was es- 
tablished by the two Italian authors who were unaware of the ex- 
istence of the genus Endamoeba (p. 444). Numerous species in ver- 
tebrates and invertebrates; one species in Protozoa. 

Fig. 189. a, Endamoeba majestus, X420 (Kirby); b, E. simulans, X420 
(Kirby); c, Entamoeba paulista in Zelleriella, X290 (Stabler and Chen). 

E. histolytica Schaudinn (1903) (Figs. 190, 191). The trophozoite 
is an active amoeba and measures 7-35 (9-20) n in diameter; cyto- 
plasm usually well differentiated; eruptive formation of large lobo- 
podia, composed largely of ectoplasm; when fresh, active monopodal 
progressive movement; the vesicular nucleus appears in life as a 
ring, difficult to recognize; food vacuoles contain erythrocytes, tissue 
cell fragments, leucocytes, etc.; stained nucleus shows a membrane, 
comparatively small peripheral granules, a centrally located small 
endosome and an indistinct network with a few scattered chromatin 
granules. The trophozoite multiplies by binary fission. The amoeba 
lives in the lumen and in the tissues of the wall of the colon, and 
brings about characteristic ulceration of the colon which is typically 
accompanied by symptoms of amoebic dysentery. Through the portal 
vein, the amoeba may invade the liver in which it produces abscess, 
and other organs such as lung, brain, testis, etc. The infection in 
these organs is referred to as amoebiasis. 

Under certain circumstances not well understood, the amoebae 
remain small after division. Such amoebae are sluggish and known 


as the precystic forms. The precystic amoeba secretes presently a 
resistant wall and becomes encysted. The highly refractile cyst is 
spherical and measures 5-20/* in diameter. At first it contains a single 
nucleus which divides twice. The mature cyst contains four nuclei. 
In addition the cyst contains diffused glycogen and elongated refrac- 
tile rod-like bodies with rounded extremities which stain deeply 
with haematoxylin (hence called chromatid bodies). These inclusions 
are absorbed and disappear as the cyst matures. No further changes 

Pi ''KJ_ 

up • 



. ■ -V 





7 p 

Fig. 190. Entamoeba histolytica, X1150 (Kudo). 1, a living trophozoite; 
2-4, stained trophozoites; 5, a fresh cyst; 6-9, stained cysts. 

take place in the cyst as long as it remains outside the host's intes- 
tine. The trophozoites are found in dysenteric or diarrhoeic faeces, 
but formed faeces usually contain cysts. The cyst is the stage by 
which the organism begins its life in a new host. 

The life-cycle of Entamoeba histolytica in human host is unknown. 
The amoeba has, however, been cultivated in vitro by numerous 
investigators since the first successful cultivation by Boeck and 
Drbohlav (1924) (p. 887). The excystment of cysts and metacystic 
development have also been observed and studied especially by 
Dobell (1928) and Cleveland and Sanders (1930) in cultures. Snyder 



and Meleney (1941) found that bacteria-free cysts usually excyst 
when suspended in various media with living bacteria and in the 
absence of bacteria, excystment was observed only in the presence 
of the reducing agents, cysteine or neutralized thioglycollic acid or 
under conditions of reduced oxygen tension. According to Dobell, 
in the process of excystation, a single tetranucleate amoeba emerges 
from a cyst through a minute pore in the cyst wall. The tetranucleate 
metacystic amoeba produces a new generation of trophozoites by a 
diverse series of nuclear and cytoplasmic divisions (Fig. 191) which 
result in production of eight uninucleate amoebulae. These amoebu- 
lae are young trophozoites which grow into larger ones. No sexual 
phenomena have been observed during these changes. It is supposed 
that when viable cysts reach the lower portion of the small intestine 
or the colon, the changes stated above take place in the lumen and 
the young uninucleate amoebulae initiate an infection. 

Q) G 
I cbeb 0[ 

I I \ I \ / I ^ 

Fig. 191. Diagram showing excystment and a common way by which 
a metacystic amoeba of Entamoeba histolytica divides into 8 uninucleate 
amoebulae (Dobell). 


While the description of Entamoeba histolytica given above applies 
in general, diversities in dimensions of trophozoites and cysts, and 
in pathogenicity in human host as well as in experimental animals 
have been reported. A number of observers are inclined to think 
that there are several varieties or races of this amoeba, as has 
already been mentioned (p. 226). 

Entamoeba histolytica, commonly known as "the dysentery 
amoeba," was first definitely recognized by Losch in Russia in 1875. 
It is now known to be widely distributed in tropical, subtropical 
and temperate regions alike, although it is more prevalent in warmer 
regions. The incidence of infection depends mainly on the sanitary 
conditions of the community, since the cysts of the organism are 
voided from host in faeces. Faecal examinations which have been 
carried on by numerous investigators in different countries of the 
world, reveal that the incidence of infection is as high as over 50 per 
cent in some areas. According to Craig (1934), 49,336 examinations 
made by many observers in various parts of the United States show 
that the infection rate varied from 0.2 to 53 per cent, averaging 11.6 
per cent, which justifies Craig's (1926) earlier estimate that about 10 
per cent of the general population harbor this protozoan. An acute 
infection by E. histolytica is accompanied by dysentery, while in 
chronic cases or in convalescence, the host may void infectious cysts 
without suffering from the infection himself. Such a person is known 
as a cyst-carrier or -passer. 

The trophozoite if voided in faeces perish in a comparatively short 
time. The dissemination of infection is thus exclusively carried on by 
the cyst. Viable cysts may be transmitted (1) by contamination of 
food through contact with contaminated water or through unsani- 
tary habit of food handlers who are cyst-carriers; (2) by droppings of 
flies and cockroaches which, as noted below, contain viable cysts for 
a comparatively long time after feeding on faeces containing cysts 
and by soiled appendages of these insects which may directly trans- 
fer the cysts to food by walking on it; and (3) by contaminated wa- 
ter in which the cysts live considerably longer than in faeces (p. 450). 

The seriousness of water-borne infection in crowded areas is easily 
realized when one recalls the outbreak (some 1400 cases) of amoebic 
dysentery and amoebiasis which originated in Chicago in 1933, where 
defective plumbing in certain establishments contaminated the wa- 
ter system with the cysts of Entamoeba histolytica (Bundesen et al., 
1936) and the development of some 100 cases of amoebic dysentery 
among firemen who drank contaminated water in connection with 
the 1934 fire of the Union Stockyards in Chicago (Hardy and Spec- 
tor), although in the latter instance, some workers believe that se- 


vere amoebic infections may have resulted from already existing 
dormant infections aided by the newly formed association with bac- 

The cysts remain viable for a considerable length of time outside 
the human intestine, if environmental conditions are favorable. Since 
information regarding the viability and longevity of the cyst is 
highly important from the epidemiological standpoint, many papers 
have dealt with it. In testing the viability of the cyst, the following 
two tests have been used by the majority of investigators. 

(a) Eosin-staining test. Kuenen and Swellengrebel (1913) first 
used a dilute solution of eosin (1:1000). It has since been used by 
Wenyon and O'Connor, Root, Boeck, and many others. Solutions 
used vary from 1:10,000 (Root) to 1:100 (Boeck). A small amount 
of fresh cyst-containing material and a drop of eosin solution are 
mixed on a slide, then dead cysts will appear stained reddish under 
the microscope, while living cysts remain unstained. Whether or not 
unstained cysts might be dead or uninfectious is unknown. But as 
Wenyon and O'Connor wrote, "if we accept the eosin test as a 
criterion and regard all unstained cysts as living, the error in judg- 
ment will be on the safe side." Root found neutral red in 1:10,000 
dilution to give a slightly larger proportion of stained cysts than 
eosin. Frye and Meleney's (1936) comparative study leads one to 
look upon this method as a fairly dependable one. 

(b) Cultivation test. Improved cultural technique now brings 
about easily excystment of viable cysts in a proper culture medium. 
For example, Yorke and Adams (1926) obtained in 24 hours "a 
plentiful growth of vegetative forms" from cysts in Locke-egg-serum 
medium (p. 887). Snyder and Meleney (1941) note recently that the 
excystation does not take place in various culture media unless liv- 
ing bacteria were added or oxygen concentration of the media was 
decreased. Animal infection method has not been used much, as 
experimental animals (cats) show individual difference in suscepti- 
bility. Some of the published results are summarized below. The 
testing method used is indicated by: a for eosin test or 6 for cultiva- 
tion test and is given after the name of the investigators. 

1. Cysts in faeces kept in a covered container. All cysts disap- 
peared in 3 days at 37°C; at 27-30°C. half of the cysts found dead 
by the 4th and all dead by the 9th day (Kuenen and Swellengrebel ; 
a). Alive for 3 weeks (Thomson and Thomson; a). Remain un- 
changed for several weeks if kept "cool and moist" (Dobell). All 
dead within 10 days at 16-20° or 0°C. (Yorke and Adams; b). 

2. Cysts kept in water emulsion. All alive on the 9th, but almost 


all dead on the 13th day (Kuenen and Swellengrebel ; a). Viable for 
25 days (Thomson and Thomson; a). Cysts in running water for 15 
days, excysted in pancreatic juice (Penfold, Woodcock and Drew). 
Viable for 30 days (Wenyon and O'Connor; a) ; for 5 weeks (Dobell) ; 
for 153 days (Boeck; a). Alive for 10 and 17 days at 16-20° and 0°C. 
respectively (Yorke and Adams; 6); for 3, 10, 30, and 90 days at 
30°, 20°, 10° and 0°C. respectively (Chang and Fair; b). 

3. Cysts in relation to high temperatures. Cysts are killed at 
68°C. in 5 minutes (Boeck; a); at 50°C. in 5 minutes (Yorke and 
Adams; 6). Dipping in boiling water for 5-10 seconds kills the cysts 
(Kessel; a). 

4. Cysts in relation to desiccation. Desiccation kills cysts instantly 
(Kuenen and Swellengrebel; Wenyon and O'Connor, Dobell, etc.). 
Therefore, the cysts carried in dust are most probably not viable 
under ordinary circumstances. 

5. Cysts in relation to chemicals. 

HgCl 2 . 0.1% solution kills cysts in 4 hours (Kuenen and 
Swellengrebel; a) ; kills readily (Lin; 6). 1 : 2500 solution kills 
cysts in 30 minutes at 20-25°C. (Yorke and Adams; 6). 

Creolin. 1 :250 solution kills cysts in 5-10 minutes (Kuenen and 
Swellengrebel; a). 

Alcohol. 50% alcohol kills cysts immediately (Kuenen and 
Swellengrebel; a); in one hour (Kessel; a). 

Formaldehyde. Cysts treated in 1% solution for 4 hours were 
apparently dead, though not stained with eosin (Wenyon 
and O'Connor). 0.5% solution kills cysts in 30 minutes at 
20-25° or 37°C. (Yorke and Adams; b). 

Cresol. 1:20, 1:30, and 1:100, killed the cysts immediately, 
in one minute and in 30 minutes respectively (Wenyon and 
O'Connor; a). 

Phenol. 1:40 and 1:100 killed cysts in 15 minutes and 7 hours 
respectively (Wenyon and O'Connor; a). 1% solution of 
phenol or lysol kills cysts in 30 minutes at 20-25° or 37°C. 
(Yorke and Adams; b). 

HC1. 7.5% solution at 20-25°C. and 5% at 37°C. kill the 
cysts in 30 minutes (Yorke and Adams; 6). 

NaOH. 2.5% solution kills cysts in 30 minutes at 20-25° or 
37°C. (Yorke and Adams; 6). 

Chlorine. 1:10,000 solution did not have any effect on cysts 
after several hours (Wenyon and O'Connor; a). 0.2% and 
0.5% solutions kill the cysts in 7 days and 72 hours respec- 
tively (Kessel; a). 0.5% and 1% solutions kill the cysts in 


36-48 and 12-24 hours respectively (Lin; 6). 1/64 of a 
saturated solution of chlorine (about 0.7 weight %) at 
20-25°C. and 1/320 solution at 37°C. killed the cysts in 30 
minutes (Yorke and Adams; b). Exposure to the residual 
chlorine 5, 8 and even 10 parts per million for 30 minutes al- 
lowed cysts to remain viable (Becker et al.). Thus the cysts 
of E. histolytica are resistant to chlorinated water far above 
the concentration which is used ordinarily in water treat- 

Potassium permanganate. 2% solution kills the cysts in 3 days 
(Kessel; a). 1 :500 solution kills cysts in 24-48 hours (Lin; b). 
]% solution does not kill cysts at 20-25° or 37°C. in 30 
minutes (Yorke and Adams; b). 

Emetin hydrochloride and yatren. 5% solutions of the two 
drugs did not have any effects upon cysts at 20-25° or 37°C. 
in 30 minutes (Yorke and Adams; 6). 

Antibiotics. The majority of antibiotics appear to inhibit the 
growth of bacteria, which results in the death of the amoeba 
in culture. Prodigiosin, however, according to Balamuth and 
Brent (1950), kills the amoebae when added in the dilution 
of 1:400,000, while bacterial flora, oxidation-reduction po- 
tentials and pH are not affected by it. 

6. Cysts in relation to passage through the intestine of insects. 
Wenyon and O'Connor found that the cysts of E. histolytica sur- 
vived as long as 24 hours in the intestines of flies, Musca domestica, 
Calliphora, and Lucilia, and living cysts were voided for 16 hours 
after feeding on faecal material containing cysts. Roubaud using 
Musca domestica, found also unaltered cysts for over 24 hours (but 
rarely after 40 hours) after taking the cysts in its gut, and if a fly 
drowned in water, the cysts remained viable for about a week. Root 
(1921) using Musca domestica, Calliphora erythrocephala (and 
Fannia caniadaris, Lucilia caesar, and Chrysomyia macellaria) found 
that about half the cysts were dead after 15 hours and last living 
cysts were found after 49 hours in the intestines of these flies after 
feeding on cyst-containing material, and that when the flies which 
ingested cysts were drowned in water, about half the cysts were 
found dead in 3 days and last living cysts were noticed on the 7th 
day. Frye and Meleney (1932) found cysts in the intestines of flies 
which were caught in 4 of 12 houses where infected subjects lived. 

Macfie (1922) reported that the cysts of Entamoeba histolytica he 
observed in the intestine of Periplaneta americana appeared un- 


harmed. Tejera (1926) reports successful experimental infection in 
two kittens that were fed on the droppings of cockroaches (sp.?) 
caught in a kitchen, which contained cysts resembling those of 
E. histolytica. Frye and Meleney (1936) observed that the cysts 
passed through the intestine of Periplaneta americana in as early as 
10-12 hours and remained in the intestine for as long as 72 hours, 
after feeding on experimental material. Cysts which stayed in the 
cockroach intestine for 48 hours gave good cultures of trophozoites 
in egg-horse-serum-Ringer medium. 


S 6 8 9 

Fig. 192. Entamoeba coli, X1150 (Kudo). 1, a living amoeba; 2-5, 
stained trophozoites; 3, an amoeba infected by Sphaerita; 6, a precystic 
amoeba; 7, a fresh cyst; 8, a stained young cyst with a large glycogen 
vacuole; 9, a stained mature cyst. 

In addition to E. histolytica, there are now known four other 
intestinal amoebae living in man. They are E. coli, Endolimax nana, 
Iodamoeba biitschlii and Dientamoeba fragilis. In Table 10 are given 
the characteristics necessary for distinguishing E. histolytica from 
the other four intestinal amoebae. 

E. coli (Grassi) (Fig. 192). The trophozoite measures 15^0/* in 
diameter; average individuals 20-35/x; cytoplasm not well differenti- 
ated; movement sluggish; endoplasm granulated, contains micro- 
organisms and faecal debris of various sizes in food vacuoles; erythro- 
cytes are not ingested, though in a few cases (Tyzzer and Geiman) 































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and in culture (Dobell, etc.), they may be taken in as food particles 
(see below); nucleus, 5-8ju in diameter, seen in vivo; compared with 
E. histolytica, the endosome is somewhat large (about 1m in diame- 
ter) and located eccentrically; peripheral granules more conspicuous. 
The precystic form, 10-30/x in diameter, resembles that of E. his- 
tolytica. Separation of the two species of amoebae by this stage is 
ordinarily impossible. 

The cyst is spherical or often ovoid, highly refractile; 10-30^ in 
diameter; immature cyst contains 1, 2 or 4 nuclei, oneor more large 
glycogen bodies with distinct outlines, but comparatively small 
number of acicular, filamentous or irregular chromato id bodies with 
sharply pointed extremities; when mature the cyst contains 8 
nuclei and a few or no chromato id bodies. The trophozoites and 
small number of cysts occur in diarrhoeic or semiformed faeces and 
the formed faeces contain mostly cysts. 

This amoeba lives in the lumen of the colon and does not enter the 
tissues of the wall. As noted above, it has been observed in a few 
instances to ingest erythrocytes, but there is no evidence to show 
that it takes them in from living tissues. This amoeba is therefore 
considered a commensal. The abundant occurrence of the tro- 
phozoite in diarrhoeic faeces is to be looked upon as a result and not 
the cause of the intestinal disturbance. This amoeba is of common 
occurrence and widely distributed throughout the world. 

Nothing is known about its life-cycle in the human intestine. 
Cultivation of cysts in vitro indicates, according to Dobell (1938), 
the following changes : The cyst content usually emerges as a single 
multinucleate amoeba through a large opening in the cyst wall. 
Prior to or during the emergence, the amoeba may divide. Normal 
mature cysts "frequently lose" 1-4 of their original 8 nuclei before 
germination, thus becoming "infranucleate" (with 4-7 nuclei). Un- 
like in E. histolytica, there is no nuclear division in the metacystic 
stages. By a series of binary divisions with random nuclear distribu- 
tion, uninucleate amoebulae are finally produced. These are young 
amoebae which develop into large trophozoites. Here also, there is 
no sexual phenomenon in the life-cycle. Nomenclature and morphol- 
ogy (Dobell, 1919, 1938). 

E. gingivalis (Gros) (E. buccalis Prowazek) (Fig. 193). This 
amoeba lives in carious teeth, in tartar and debris accumulated 
around the roots of teeth, and in abscesses of gums, tonsils, etc. The 
trophozoite is as active as that of E. histolytica; 8-30> (average 
10-20>) in diameter; cytoplasm well differentiated; monopodal 
progressive movement in some individuals; endoplasm hyaline, but 


vacuolated, and contains ordinarily a large number of pale greenish 
bodies (which are probably nuclei of leucocytes, pus cells or other 
degenerating host cells) and bacteria in food vacuoles; nucleus, 2-4/x 
in diameter, appears as a ring ; when stained it shows a small central 
endosome and small peripheral granules closely attached to the 


~Qm -V-. <#** 




Fig. 193. Entamoeba gingivalis, X1150 (Kudo). 1, 2, living amoebae; 
3-7 stained amoebae. 

membrane. Stabler (1940) observed 5 chromosomes during binary 
fission. Encysted forms have not been observed in this amoeba. 
Kofoid and Johnstone (1930) reported having seen the same organ- 
ism in the mouth of monkeys (Rhesus and Cynomolgus) from south- 
east Asia. 

E. gingivalis is the very first parasitic amoeba that has become 
known to man. Gros (1849) found it in Russia in the tartar on the 
surface of the teeth. Some observers maintain that this amoeba is the 
cause of pyorrhoea alveolaris, but evidence for such an assumption 
seems to be still lacking. It has been found in the healthy gums and 
even in false teeth (Lynch). Therefore, it is generally considered as 
a commensal. It is widely distributed and of common occurrence. 

In the absence of the encysted stage, it is supposed that the 
organism is transmitted in trophic forms. According to Koch (1927) 
who studied the effects of desiccation and temperatures upon the 
amoeba in culture, the amoeba is killed at 0°C. in 18 hours, at 5°C. 
in 24 hours, at 10°C. in 48 hours, at 45°C. in 20 minutes, at 50°C. in 
15 minutes, and at 55°C. in 2 minutes. At 40°C, the survival is said 
to be for an indefinite length of time. Complete desiccation of the 
culture medium or immersion in water at 60°C. kills the amoeba. She 


considered that E. gingivalis may be disseminated both by direct 
contact and by intermediate contaminated articles. Nuclear division 
(Stabler, 1940; Noble, 1947). 

E. gedoelsli Hsiung (E. intestinalis (Gedoelst)). In the colon and 
caecum of horse; 6-13ju by 6-1 1/x; endosome eccentric; bacteria- 

E. equi Fantham. 40-50m by 23-29^; nucleus oval; cysts tetra- 
nucleate, 15-24/z in diameter; seen in the faeces of horse; Fantham 
reports that the endoplasm contained erythrocytes. 

E. bovis Liebetanz. 5-20/x in diameter; uninucleate cysts, 4-15/z in 
diameter; in the stomach of cattle and gnu, Cunnochaetes taurinus 
(Mackinnon and Dibb, 1938). Morphology (Noble, 1950). 

E. ovis Swellengrebel. Cyst uninucleate; in the intestine of sheep. 

E. caprae Fantham. In goat intestine. 

E. polecki (Prowazek). In the colon of pigs; 10-12/z in diameter; 
cyst uninucleate, 5-1 1/z in diameter. 

E. debliecki Nieschulz (Fig. 194, a). 5-lO^t in diameter; cysts uni- 
nucleate; in the intestine of pigs and goats. Two races (Hoare, 1940) ; 
morphology (Nieschulz, 1924) ; Entamoebae of domestic animals (No- 
ble and Noble, 1952). 

E. venaticum Darling. In the colon of dog; similar to E. histolytica; 
since the dog is experimentally infected with the latter, this amoeba 
discovered from spontaneous amoebic dysentery cases of dogs, in 
one of which were noted abscesses of liver, is probably E. histolytica. 

E. cuniculi Brug. Similar to E. coli in both trophic and encysted 
stages; in the intestine of rabbits. 

E. cobayae Walker (E. caviae Chatton). Similar to E. coli; in the 
intestine of guinea-pigs (Nie, 1950). 

E. muris (Grassi) (Fig. 194, b, c). In the caecum of rats and mice; 
trophozoite 8-30 /z; cytoplasm with rod-shaped or fusiform bacteria 
and flagellates coinhabiting the host's organ; nucleus 3-9/* in diame- 
ter and resembles closely that of E. coli; cysts 9-20/x in diameter, 
with eight nuclei when mature. Nuclear division (Wenrich, 1940); 
food habits (Wenrich, 1941). 

E. citelli Becker (Fig. 194, d, e). In the caecum and colon of the 
striped ground squirrel, CiteUus tridecemlineatus ; rounded tropho- 
zoites 10-25m in diameter; nucleus 4-6/* in diameter, with a compara- 
tively large endosome which varies in position from central to 
perpheral; cysts with eight nuclei, about 15m in diameter. 

E. gallinarum Tyzzer. In the caeca of chicken, turkeys and pos- 
sibly other fowls; trophozoites 9-25 (16-18)//; cysts octonucleate, 
15^ bv 12ju. 



E. testudinis Hartmann. In intestine of turtles, Tesludo graeca, 
T. argentina, T. calcarata and Terrapene Carolina. 

E. barreti (Taliaferro and Holmes) (Fig. 194, /). In the colon of 
snapping turtle, Chelydra serpentina; trophozoites 14-23 (18)^ long. 
Cultivation (Barret and Smith, 1924). 

E. terrapinae Sanders and Cleveland (Fig. 194, g, h). Trophozoites 
10-15/x long; cysts 8-14/z in diameter, tetranucleate when mature; 

Fig. 194. a, a stained cyst of Entamoeba debliecki, X1330 (Hoare); 
b, c, E. muris, X1330 (Wenrich) (b, with fusiform bacilli; c, with Tri- 
trichomonas muris); d, e, stained trophozoite and cyst of E. citelli, X880 
(Becker); f, a stained trophozoite of E. barreti, X1330 (Taliaferro and 
Holmes); g, h, stained trophozoite and cyst of E. terrapinae, X1665 
(Sanders and Cleveland); i, j, stained trophozoite and cyst of E. invadens, 
X1045 (Geiman and Ratcliffe). 

upon excystment, the cyst content divides into four uninucleate 
amoebulae; in the colon of Chrysemys elegans (Sanders and Cleve- 
land, 1930). 

E. invadens Rodhain (Figs. 2, a, b; 194, i,j). Resembles E. histoly- 
tica. Trophozoites measure 15.9/x in average diameter (9. 2-38. 6 /z by 
9-30m); active locomotion; feed on leucocytes, liver cells, epithelial 
cell debris, bacteria, etc.; nucleus simliar to that of E. histolytica. 
Cysts 13. 9m (11-20/z) in diameter; 1-4 nuclei; glycogen vacuole; 
chromatoid bodies acicular, rod-like or cylindrical. 

Hosts include various reptiles: Varanus salvator, V. varius, 
Tiliqua scincoides, Pseudoboa clelia, Lampropeltis getulus, Ancis- 


trodon mokasen, Natrix rhombifer, N. sipedon, N. sipedon sipedon, 
N. cyclopion, Python sebae, Rachidelus brazili, etc. Zoological Gar- 
dens in Philadelphia (Geiman and Ratcliffe) and Antwerp (Rodhain). 

The amoeba produces lesions in the stomach, duodenum, ileum, 
colon and liver in host animals. Time for excystation in host's intes- 
tine (jejunum and ileum) five to 14 hours; time for metacystic devel- 
opment in host's intestine seven-24 hours; the excysted amoeba with 
four nuclei, each of which divides once, divides finally into eight 
amoebulae; optimum temperature for culture 20-30°C. (Geiman and 
Ratcliffe, 1936). Ratcliffe and Geiman (1938) observed spontaneous 
and experimental amoebiasis in 32 reptiles. 

E. ranarum (Grassi). In colon of various species of frogs; re- 
sembles E. histolytica; 10-50/x in diameter; cysts are usually tetranu- 
cleate, but some contain as many as 16 nuclei; amoebic abscess of 
the liver was reported in one frog. Comparison with E. histolytica 
(Dobell, 1918); life cycle (Sanders, 1931). 

E. (?) phallusiae Mackinnon and Ray. In the intestine of the ascid- 
ian, Phallusia mamillata; 15-30m by 10-15m; nucleus about 5ju in 
diameter, structure not well defined; cysts uninucleate, about 20/z 
in diameter; parasitic nutrition. 

E. minchini Mackinnon. In gut of tipulid larvae; 5-30/x in diam- 
eter; cyst nuclei up to 10 in number. 

E. apis Fantham and Porter. In Apis mellifica; similar to E. coli. 

E. thomsoni Lucas. In the colon of cockroaches; when rounded 
7-30 (15-25)m in diameter; usually attached to debris by a knob- 
like process, highly adhesive; cytoplasm poorly differentiated; vesic- 
ular nucleus with peripheral granules; endosome variable, with 
loosely aggregated granules and a central dot; cysts 8-16/x in diame- 
ter, with one to four nuclei (Lucas, 1927). 

E. aulastomi Noller. In the gut of the horse-leech, Haemopis san- 
guisuga; cysts with four nuclei. Morphology nad development 
(Bishop, 1932). 

E. paulista (Carini) (Brumptina paulista C.) (Fig. 189, c). In the 
cytoplasm of many species of Protociliata; trophozoites 5.3-14. 3/z 
in diameter; cysts about 9.4/x in diameter, uninucleate; no effect upon 
host ciliates even in case of heavy infection (Stabler and Chen, 1936; 
Chen and Stabler, 1936). Carini and Reichenow (1935) : trophozoites 
8-14jii in diameter; cysts 8-12/i; either identical with E. ranarum or 
a race derived from it. 

Genus Iodamoeba Dobell. Vesicular nucleus, with a large en- 
dosome rich in chromatin, a layer of globules which surrounds the 
endosome and do not stain deeply, and achromatic strands between 



the endosome and membrane (Fig. 187, c); cysts ordinarily uninu- 
cleate, contain a large glycogenous vacuole which stains conspicu- 
ously with iodine; in intestine of man and mammals (Dobell, 1919). 
I. butschlii (Prowazek) (7. williamsi P.) (Fig. 195). The tropho- 
zoite is 6-25/x (average 8-1 5/z) in diameter; fairly active with pro- 
gressive movement, when fresh; cytoplasm not well differentiated; 
endoplasm granulated, contains bacteria and yeasts in food vacu- 
oles; the nucleus (3-4/x in diameter) visible in vivo; the large endo- 
some about \ the diameter of nucleus, surrounded by small spherules. 

.;. ' ® 



Fig. 195. Iodamoeba butschlii, X1150 (Kudo). 1, a living amoeba; 2-5, 
stained trophozoites; 4, 5, somewhat degenerating trophozoites; 0, a fresh 
cyst; 7-10, stained cysts. 

The cysts are spherical, ovoid, ellipsoid, triangular, pyriform or 
square; rounded cysts measure about 6-1 5/* in the largest diameter; 
a large glycogen body which becomes conspicuously stained with 
Lugol's solution (hence formerly called "iodine cysts") persists; 
nucleus with a large, usually eccentric endosome. 

The trophozoites and cysts are ordinarily present in diarrhoeic 
faeces, while the formed faeces contain cysts only. This amoeba ap- 
parently lives in the lumen of the colon and does not seem to attack 
host's tissues and is, therefore, considered to be a commensal. No- 
menclature (Dobell, 1919); nuclear structure (Wenrich, 1937a). 

I. suis O'Connor. In colon of pig; widely distributed; indis- 
tinguishable from I. butschlii; it is considered by some that pigs are 
probably reservoir host of I. butschlii. 

Genus Endolimax Kuenen and Swellengrebel. Small; vesicular 
nucleus with a comparatively large irregularly shaped endosome, 



composed of chromatin granules embedded in an achromatic ground 
mass and several achromatic threads connecting the endosome with 
membrane (Fig. 187, d); commensal in hindgut in man and animals. 
Several species. 

E. nana (Wenyon and O'Connor) (Fig. 196, a-d). The trophozoite 
measures 6-18ju in diameter; fairly active monopodal movement by 
forming a broad pseudopodium; when stationary pseudo podia are 
formed at different points; endoplasm is granulated and contains 
bacteria as food particles; the vesicular nucleus, 1.5-3/x in diameter, 
is composed of a delicate membrane with a few chromatin granules 
and a large irregularly shaped endosome. 

Fig. 196. a-d, Endolimax nana, X2300 (Kudo) (a, b, living and 
stained trophozoites; c, d, fresh and stained cysts); e, f, stained tropho- 
zoite and cyst of E. clevelandi, X3000 (Gutierrez-Ballesteros and Wen- 
rich); g, h, stained trophozoites of Martinezia baezi, XI 700 (Hegner and 

The cyst is usually ovoid; young cyst contains 1 or 2 nuclei; mature 
cyst with 4 nuclei; indistinctly outlined glycogen body may be 
present while immature; dimensions 5-12/x (majority 7-10/i) in 

The trophozoites are found in diarrhoeic or semifluid faeces to- 
gether with the cysts, and formed faeces contain cysts. This amoeba 
is coelozoic in the lumen of the upper portion of colon and is consid- 
ered to be a commensal. Cytology and life-history (Dobell, 1943). 

E. caviae Hegner. In the caecum of guinea-pigs. Morphology (Heg- 
ner, 1926; Nie, 1950). 



E. grcgariniformis (Tyzzer). In the caeca of fowls; 4-12ju in di- 
ameter; cysts uninucleate (Tyzzer, 1920). 

E. clevelandi Gutierrez-Ballesteros and Wenrich (Fig. 196, e, /). 
In the rectal contents of Pseudemys floridana mobilensis ; tropho- 
zoites 5-1 -ijj, in diameter; cysts tetranucleate, 4.5-10/z large. 

E. ranarum Epstein and Ilovaisky. In the colon of frogs; cysts 
octonucleate, up to 25/x in diameter. 

E. blattae Lucas. In the colon of cockroaches; trophozoites 3-1 5/z 
long; cysts, 7-1 l^t in diameter and with one to three nuclei (Lucas, 

Genus Dientamoeba Jepps and Dobell. Small amoeba; number of 
binucleate trophozoites often greater than that of uninucleate 
forms; nuclear membrane delicate; endosome consists of several 
chromatin granules embedded in plasmosomic substances and 
connected with the membrane by delicate strands (Fig. 187, e) ; in 
colon of man (Jepps and Dobell, 1918). 

Fig. 197. Dientamoeba fragilis, X2300 (Kudo), a, b, living bi- and 
uni-nucleate trophozoites; c, d, stianed uni- and bi-nucleate tropho- 

D. fragilis J. and D. (Fig. 197). The trophozoite is actively amoe- 
boid; 4-18/x (average 5-12/x) in diameter; progressive movement; 
cytoplasm well differentiated; endoplasm granulated contains bac- 
teria in food vacuoles; nucleus onl} r faintly visible; 1 or 2 nuclei, the 
ratio is variable; in some material binucleate forms may be 80% or 
more (Jepps and Dobell), while in others uninucleate forms may pre- 
dominate (Kudo, 1926a; Wenrich, 1937); nucleus is made up of a 
delicate membrane and a large endosome (more than one-half the 
diameter of nucleus) in which are embedded 4-8 chromatin granules 
along the periphery. According to Dobell (1940), the binucleate con- 
dition represents an arrested telophase stage of mitosis and the 
chromatin granules are in reality chromosomes, probably 6 in num- 
ber. Comparison with Histomonas meleagridis (p. 335) led this author 
to think that this amoeba may be an aberrant flagellate closely re- 
lated to Histomonas. 


Encysted stage has not been observed. Degenerating trophozoites 
often develop vacuoles which coalesce into a large one and the or- 
ganisms may then resemble Blastocystis hominis (p. 893) which is 
very common in faeces. Transmission may be carried on by tropho- 
zoites. According ot Wenrich (1940), this amoeba if left in the faeces 
remains alive up to 48 hours at room temperature, but disappears 
probably by disintegration in 2 hours at 3.5°C. Since all attempts 
to bring about experimental infection by mouth or by rectum failed, 
Dobell considered that the amoeba may be transmitted from host 
to host in the eggs of nematodes such as Trichuris or Ascaris, as in 
the case of Histomonas (p. 335). 

The amoeba inhabits the lumen of the colon. There is no indica- 
tion that it is histozoic or cytozoic. Some workers attribute certain 
intestinal disturbances to this amoeba, but no definite evidence for 
its pathogenicity is available at present. It seems to be widely dis- 
tributed, but not as common as the other intestinal amoebae men- 
tioned above, although in some areas it appears to be common. Nu- 
clear division (Wenrich, 1936, 1939, 1944a; Dobell, 1940). 

Genus Martinezia Hegner and Hewitt. The nucleus consists of a 
wrinkled membrane, a large compact or granular endosome and 
heavy peripheral beads; cysts unknown; parasitic. 

M. baezi H. and H. (Fig. 196, g, h). In the intestine of iguanas, 
Ctenosaura acanthura; 8-21/* by 6.5-16/*; nucleus about 4/* in diame- 
ter; two nuclei in about 3 per cent of the organisms; cysts not seen. 

Genus Dobellina Bishop and Tate. Trophozoite: small amoeba; 
ectoplasm and endoplasm differentiated; usually monopodal; 
nucleus one to many ; nucleus with a large central endosome and an 
achromatic nuclear membrane; nuclear divisions mitotic and simul- 
taneous; no solid food vacuoles; no contractile vacuole; with refrin- 
gent granules. Cysts: spherical; thin-walled; devoid of glycogen and 
of chromatoid bodies; 2 or more nuclei; parasitic (Bishop and Tate, 

D. mesnili (Keilin) (Fig. 198, a-c). Uninucleate amoebae as small 
as 3.6/* in diameter; multinucleate forms 20-25/* by 10-15/*; cysts 
8-11/* in diameter; in the space between the peritrophic membrane 
and the epithelium of the gut in the larvae of Trichocera hiemalis, 
T. annulata, and T. regelationis (winter gnats). 

Genus Schizamoeba Davis. Nucleus vesicular, without endosome, 
but with large discoid granules arranged along nuclear membrane; 1 
to many nuclei; cyst-nuclei formed by fragmentation of those of 
the trophozoite and possess a large rounded chromatic endosome, 
connected at one side with the nuclear membrane by achromatic 


strands to which chromatin granules are attached; in stomach of 
salmonid fish. One species (Davis, 1926). 

S. salmonis D. (Fig. 198, d, e). Sluggish amoeba; 10-25/* in di- 
ameter; 1 to several nuclei; multiplication by binary fission; nuclear 
division amitotic. Cysts are said to be more abundant than tropho- 
zoites and their appearance seems to be correlated with the amount 
of available food; cysts spherical, 15-35/t in diameter; cyst-mem- 
brane thin and nuclei vary from 3 to many; during encystment, 
chromatin bodies of trophozoite become collected in several masses 
which then break up and each chromatin grain becomes the endo- 
some of newly formed nucleus; cyst contents divide sooner or later 
into 4-11 multinucleate bodies and the whole increases in size; 
finally cyst-membrane disintegrates and the multinucleate bodies 
become set free. Trophozoites are said to occur in the mucous 
covering of stomach of host fish; cysts occur in both stomach and 
intestine. Aside from the loss of certain amount of available food, no 
pathogenic effect of the amoeba upon the host fish was noticed 

Genus Hydramoeba Reynolds and Looper. Nucleus vesicular 
with a large central endosome composed of a centriole (?) and 
chromatin granules embedded in an achromatic mass, achromatic 
strands radiating from endosome to membrane; a ring made up of 
numerous rod-shaped chromatin bodies in the nuclear-sap zone; 1 
or more contractile vacuoles; apparently the most primitive para- 
sitic amoeba; parasitic on Hydra. 

H. hydroxena (Entz) (Fig. 198, f-l). Parasitic in various species 
of Hydra; first observed by Entz; Wermel found 90 per cent of Hydra 
he studied in Russia were infected by the amoeba; Reynolds and 
Looper (1928) stated that infected Hydra die on an average in 6.8 
days and that the amoebae disappear in 4-10 days if removed from a 
host hydra. More or less spheroidal, with blunt pseudopods; 60- 
380/i in diameter; nucleus shows some 20 refractile peripheral gran- 
ules in life; contractile vacuoles; food vacuoles contain host cells; 
multiplication by binary fission. 

Ito (1949) found this organism in Hydra japonica, H. magnipapil- 
lata, Palmathydra robusta, etc. in Japan. The trophozoites measured 
26-2 10m long with a nucleus, 10-12/x in diameter. Early infection 
occurs on the tip of tentacles and spreads to the body proper (Fig. 
198, i-l). Since the tentacles remain contracted, the host hydra can- 
not feed on food organisms and becomes "depressed." The amoebae 
finally enter the coelenteric cavity and feed on the endoderm cells. 
The host hydra becomes spherical. At25°C. death of the hydra may 



occur in one week. Encystment takes place soon after the death of 
the host or occasionally when the organisms become detached from 
the host; cysts are spherical, measure 27.5-29m, and contain one or 
more nuclei, nematocysts and a large vacuole (h). Nuclear division 
(Reynolds and Threlkeld, 1929). 

Fig. 198. a-c, Dobellina mesnili (Bishop and Tate) (a, b, stained uni- 
and multi-nucleate trophozoites, X2200; c, a stained cyst with six nu- 
clei, X1760); d, e, stained trophozoite and cyst of Schizamoeba salmonis, 
X1070 (Davis); f-1, Hijdramoeba hydroxena (f, h-1, Ito; g, Reynolds and 
Looper) (f, a trophozoite in life, X330; g, a trophozoite feeding on ecto- 
dermal cells of a Hydra in section, X470; h, a living cyst, X530; i-1, 
stages of infection in Hydra, X6.5); m, Paramoeba pigmentifera with its 
nucleus in center, X800 (Janicki). 

Family 4 Paramoebidae Poche 

Genus Paramoeba Schaudinn. The amoeba possesses a nucleus and 
nucleus-like secondary cytoplasmic structure, both of which mul- 
tiply by division simultaneously; free-living or parasitic. 

P. pigmentifera (Grassi) (Fig. 198, m). About 30/x long; sluggish; 


cytoplasm distinctly differentiated; secondary body larger than the 
nucleus; flagellated swarmers are said to occur; parasitic in coelom 
of Chaetognatha such as Sagitta claparedei, Spadella bipunctata, S. 
inflata, and S. serratodentata. Cytology (Janieki, 1928, 1932). 

P. schaudinni Faria, da Cunha and Pinto. About 7-22/x in diame- 
ter; in salt water; Rio de Janeiro, Brazil. 


Andresen, N.: (1942) Cytoplasmic components in the amoeba, 
Chaos chaos L. C. R. Lab. Carlsberg, Ser. chim., 24: 139. 

Angerer, C. A.: (1942) The action of cupric chloride on the proto- 
plasmic viscosity of Amoeba dubia. Physiol. Zool., 15:436. 

Balamuth, W. and Brent, M. M.: (1950) Biological studies on 
Entamoeba histolytica. IV. Proc. Soc. Exper. Biol. Med., 75:374. 

Barret, H. P. and Smith, Nanine M.: (1924) The cultivation of an 
Endamoeba from the turtle, Chelydra serpentina. Am. J. Hyg., 

Becker, E. R. : (1926) Endamoeba citelli sp. nov., etc. Biol. Bull., 

■ , Burks, C. and Kaleita, E.: (1946) Cultivation of Enda- 
moeba histolytica in artificial media from cysts in drinking water 
subjected to chlorination. Am. J. Trop. Med., 26:783. 

Belda, W. H.: (1942) Permeability to water in Pelomyxa carolinen- 
sis. I. Salesianum, 37:68. 

— (1942a) II. Ibid., 37:125. 

— (1943) III. Ibid., 38:17. 

Bishop, Ann: (1932) Entamoeba aulastomi. Parasitology, 24:225. 

(1937) Further observations upon Entamoeba aulastomi. 

Ibid., 29:57. 

and Tate, P.: (1939) The morphology and systematic posi- 

tion of Dobellina mesnili, etc. Ibid., 31:501. 
Bundesen, H. N., Conolly, J. I. et al.: (1936) Epidemic amebic 

dysentery: etc. Nat. Inst. Health Bull., no. 166. 
Carini, A.: (1933) Parasitisme des Zellerielles par des microorga- 

nismes nouveaux (Brumptina n.g.). Ann. Parasit., 11:297. 
(1943) Novas observacoes em batraquios e ofidios, etc. Arqu. 

Biol., 27:1. 
and Reichenow, E.: (1935) Ueber Amoebeninfektion in 

Zelleriellen. Arch. Protist., 84:175. 
Casagrandi, 0. and Barbagallo, P.: (1895) Ricerche biologiche e 

clinique suh" Amoeba coli. I, II. Nota prelim. Bull. Accad. 

Gioenia Sc. Nat. Catania, 39:4 and 41:7. 
Cash, J.: (1905) The British freshwater Rhizopoda and Heliozoa. 1. 

Chalkley, H. W.: (1936) The behavior of the karyosome and the 

"peripheral chromatin" during mitosis, etc. J. Morphol., 60:13. 
and Daniel, G. E.: (1933) The relation between the form of 

the living cell and the nuclear phases of division in Amoeba 

proteus. Physiol. Zool., 6:592. 


Chen, T. T. and Stabler, R. M.: (1936) Further studies on the 

Endamoeba parasitizing opalinid ciliates. Biol. Bull., 70:72. 
Cleveland, L. R. and Sanders, E. P.: (1930) Encystation, multiple 

fission without encystment, excvstation, etc. Arch. Protist., 70: 

Craig, C. F.: (1934) Amebiasis and amebic dysentery. Springfield, 

Dangeard, P. A.: (1900) Etude de la karyokinese chez V Amoeba 

hyalina. Le Bot., Ser. 7:49. 
Daniels, E. W.: (1951) Studies on the effect of x-irradiation upon 

Pelomyxa carolinensis with special reference to nuclear division 

and plasmotomy. J. Exper. Zool., 117:189. 
(1952) Some effects on cell division in Pelomyxa carolinensis 

following x-irradiation, etc. Ibid., 120:509. 

(1952a) Cell division in the giant amoeba, Pelomyxa caroli- 

nensis, following x-irradiation. I. Ibid., 120:525. 
Davis, H. S.: (1926) Schizamoeba salmonis, a new ameba parasitic in 

salmonid fishes. Bull. Bur. Fisheries, 42, 8 pp. 
Dawson, J. A.: (1945) Studies on the contractile vacuole of Amoeba 

dubia. J. Exper. Zool., 100:179. 

— , Kessler, W. R. and Silverstein, J. K.: (1935) Mitosis in 

Amoeba dubia. Biol. Bull, 69:447. 
Dobell, C: (1918) Are Entamoeba histolytica and E. ranarum the 

same species? Parasitology, 10:294. 

■ (1919) Amoebae living in man. London. 

(1928) Researches on the intestinal Protozoa of monkeys and 

man. I, II. Parasitology, 20:359. 

(1938) IX. Ibid., 30:195. 

(1940) X. Ibid., 32:417. 

- (1943) XI. Ibid., 35:134. 

and O'Connor, F. W. : (1921) The intestinal Protozoa of 

man. London. 

Douglas, M.: (1930) Notes on the classification of the amoeba, etc. 
J. Trop. Med. Hyg., 33:258. 

Entz, G. Jr.: (1912) Ueber eine neue Amoebe auf Susswasser-Poly- 
pen {Hydra oligactis). Arch. Protist., 27:19. 

Geiman, Q. M. and Ratcliffe, H. L.: (1936) Morphology and life- 
cycle of an amoeba producing amoebiasis in reptiles. Parasitol- 
ogy, 28:208. 

Greeff, R. : (1874) Pelomyxa palustris (Pelobius), ein amoebenar- 
tiger Organismus des siissen Wassers. Arch. mikr. Anat., 10:53. 

Groot, A. A. de: (1936) Einige Beobachtungen an Dinamoeba mira- 
bilis. Arch. Protist., 87:427. 

Gutierrez-Ballesteros, E. and Wenrich, D. H.: (1950) Endo- 
limax clevelandi, n. sp. from turtle. J. Parasit., 36:489. 

Hardy, A. V. and Spector, B. K.: (1935) The occurrence of infes- 
tations with E. histolytica associated with water-borne epidemic 
diseases. Publ. Health Rep. Washington, 50:323. 

Hartmann, M. and Chagas, C.: (1910) Ueber die Kernteilung von 
Amoeba hyalina. Mem. Inst. Oswaldo Cruz, 2:159. 


Hegner, R. W.: (1926) Endolimax caviae, etc. J. Parasit., 12:146. 
Hemming, F.: (1951) Report on the investigation of the nomencla- 

torial problems associated with the generic names u Endamo- 
eba^ etc. Bull. Zool. Nomenclature, 2:277. 
Henderson, J. C: (1941) Studies of some amoebae from a termite 

of the genus Cubitermes. Univ. California Publ. Zool., 43:357. 
Hewitt, R.: (1937) The natural habitat and distribution of Hart- 

mannella castellanii, etc. J. Parasit., 23:491. 
Hoare, C. A.: (1940) On an Entamoeba occurring in English goats. 

Parasitology, 32:226. 
Hogue, Mary J.: (1921) Studies on the life history of Vahlkampjla 

patuxent, etc. Am. J. Hyg., 1:321. 
Hollande, A.: (1945) Biologie et reproduction des rhizopodes des 

genres Pelomyxa et Amoeba, etc. Bull. Biol. France et Belg., 

Hyman, Libbie H.: (1936) Observations on Protozoa. I. Quart. J. 

Micr. Sc, 79:43. 
Ito, T. : (1949) On Hydramoeba hydroxena discovered in Japan. Sc. 

Rep. Tohoku Univ., Ser. 4, 18:205. 
Janicki, C: (1928) Studien an Genus Paramoeba Schaud. Neue 

Folge. I. Zeitschr. wiss. Zool., 131:588. 

(1932) II. Ibid., 142:587. 

Jepps, Margaret W. and Dobell, C: (1918) Dientamoeba fragilis, 

etc. Parasit., 10:352. 
Jollos, V. : (1917) Untersuchungen zur Morphologie der Amoeben- 

teilung. Arch. Protist., 37:229. 
Keller, H.: (1949) Untersuchungen iiber die intrazellularen Bak- 

terien von Pelomyxa palustris. Ztschr. Naturforsch., 46:293. 
Kirby, H. Jr.: (1927) Studies on some amoebae from the termite 

Microtermes, etc. Quart. J. Micr. Sc, 71:189. 
(1945) Entamoeba coli versus Endamoeba coli. J. Parasit., 31 : 

Koch, D. A.: (1927) Relation of moisture and temperature to the 

viability of Endamoeba gingivalis in vitro. Univ. California 

Publ. Zool., 31:17. 
Kofoid, C. A. and Johnstone, H. G.: (1930) The oral amoeba of 

monkeys. Ibid., 33:379. 
Kudo, R. R. : (1926) Observations on Endamoeba blattae. Am. J. 

Hyg., 6:139. 
(1926a) Observations on Dientamoeba fragilis. Am. J. Trop. 

Med., 6:299. 
(1946) Pelomyxa carolinensis Wilson. I. Jour. Morph., 78: 


(1947) II. Ibid., 80:93. 

(1949) III. Ibid., 85:163. 

(1950) A species of Pelomyxa from Illinois. Tr. Am. Micr. 

Soc, 69:368. 
(1951) Observations on Pelomyxa illinoisensis. Jour. Morph., 


- (1952) The genus Pelomyxa. Tr. Am. Micr. Soc, 71 : 108. 


Kuenen, W. A. and Swellengrebel, N. H.: (1913) Die Entamoe- 
ben des Menschen und ihre praktische Bedeutung. Centralbl. 
Bakt. I. Orig., 71:378. 

Lapage, G.: (1922) Cannibalism in Amoeba vespertilio. Quart. J. 
Micr. Sc, 66:669. 

Leidy, J.: (1879) Freshwater rhizopods of North America. Rep. 
U. S. Geol. Survey Terr., 12. 

Liesche, W.: (1938) Der Kern- und Fortpflanzungsverhaltnisse von 
Amoeba proteus. Arch. Protist., 91:135. 

Lucas, Catherine L. T. : (1927) Two new species of amoeba found 
in cockroaches: etc. Parasitology, 19:223. 

Mackinnon, Doris L. and Ray, H. N.: (1931) An amoeba from the 
intestine of an ascidian at Plymouth. J. Mar. Biol. Ass. United 
Kingdom, 17:583. 

and Dibb, M. J.: (1938) Report on intestinal Protozoa of 

some mammals, etc. Proc. Zool. Soc. London, B, 108:323. 

Mast, S. 0.: (1926) Structure, movement, locomotion and stimula- 
tion in Amoeba. J. Morphol., 14:347. 

(1934) Amoeboid movement in Pelomyxa palustris. Physiol. 

Zool., 7:470. 

• (1938) Amoeba and Pelomyxa vs. Chaos. Turt. News, 16: 


and Doyle, W. L.: (1935) Structure, origin and function of 

cytoplasmic constituents in Amoeba proteus. I. Arch. Protist., 

(1935a) II. Ibid., 86:278. 

and Johnson, P. L.: (1931) Concerning the scientific name 

of the common large amoeba, usually designated Amoeba pro- 
teus. Ibid., 75:14. 

Meglitsch, P. A.: (1940) Cytological observations on Endamoeba 
blattae. Illinois Biol. Monogr., 14: no. 4. 

Mercier, L.: (1909) Le cycle evolutif d' Amoeba blattae. Arch. Pro- 
tist., 16:164. 

Morris, S.: (1936) Studies of Endamoeba blattae. J. Morphol., 59: 

Musacchia, X. J.: (1950) Encystment in Pelomyxa carolinensis. St. 
Louis "Univ. Stud., Sec. C, 1, 6 pp. 

Nie, D.: (1950) Morphology and taxonomy of the intestinal Pro- 
tozoa of the guinea-pig, Cavia porcella. J. Morphol., 86:381. 

Nieschulz, O.: (1924) Ueber Entamoeba deblicki mihi, eine Darm- 
amoebe des Schweines. Arch. Protist., 48:365. 

Noble, E. R.: (1947) Cell division in Entamoeba gingivalis. Univ. 
California Publ. Zool., 53:263. 

■ (1950) On the morphology of Entamoeba bovis. Ibis., 57:341. 

Noble, G. A. and Noble, E. R.: (1952) Entamoebae in farm mam- 
mals. J. Parasit., 38:571. 

Okada, Y. K. : (1930) Transplantationsversuche an Protozoen. Arch. 
Protist., 69:39. 

(1930a) Ueber den Bau und die Bewegungsweise von 

Pelomyxa. Ibid., 70:131, 


Penard, E.: (1902) Faune rhizopodique du bassin du Leman. Ge- 

Raabe, H.: (1951) Amoeba vespertilio Penard; etc. Bull. Int. Acad. 
Pol. Sci. et Lett., Ser. B., p. 353. 

Rafalko, J. S.: (1947) Cytological observations on the amoebo- 
flagellate, Naegleria gruberi. J. Morphol., 81:1. 

Ratcliffe, H. L. and Geiman, Q. M.: (1938) Spontaneous and ex- 
perimental amebic infection in reptiles. Arch. Path., 25:160. 

Reynolds, B. D. and Looper, J. B. : (1928) Infection experiment 
with Hydr amoeba hydroxena. J. Parasit., 15:23. 

and Threlkeld, W. L.: (1929) Nuclear division in Hy- 
dramoeba hydroxena. Arch. Protist., 68:305. 

Rice, N. E.: (1945) Pelomyxa carolinensis (Wilson) or Chaos chaos 
(Linnaeus)? Biol. Bull., 88:139. 

Rodhain, J.: (1934) Entamoeba invadens n. sp., etc. C. R. Soc. Biol., 

Root, F. M.: (1921) Experiments on the carriage of intestinal Pro- 
tozoa of man by flies. Am. J. Hyg., 1:131. 

Sanders, Elizabeth P.: (1931) The life-cycle of Entamoeba rana- 
rum. Arch. Protist., 74:365. 

and Cleveland, L. R.: (1930) The morphology and life-cycle 

of Entamoeba terrapinae, etc. Ibid., 70:267. 

Schaeffer, A. A.: (1916) Notes on the specific and other character- 
istics of Amoeba proteus, etc. Ibid., 37:204. 

(1926) Taxonomy of the amebas. Papers Dep. Mar. Biol., 

Carnegie Inst. Washington, 24. 

(1937) Rediscovery of the giant ameba of Roesel, etc. Turt. 

News, 15:114. 

(1938) Significance of 3-daughter division in the giant 

amoeba. Ibid., 16:157. 

Schaudinn, F.: (1896) Ueber den Zeugungskreis von Paramoeba 
eilhardi, etc. Math, naturwiss. Mitt., 1:25. 

(1903) Untersuchungen ueber die Fortpflanzung einiger 

Rhizopoden. Arb. kaiserl. Gesundh.-Amte, 19:547. 

Singh, B. N.: (1952) Nuclear division in nine species of small free- 
living amoebae, etc. Phil. Tr. Roy. Soc. London, Ser. B, 236: 

Snyder, T. L. and Meleney, H. E.: (1941) The excystation of 
Endamoeba histolytica in bacteriologically sterile media. Am. J. 
Trop. Med., 21:63. 

Stabler, R. M.: (1940) Binary fission in Entamoeba gingivalis. J. 
Morphol., 66:357. 

— and Chen, T. T. : (1936) Observations on an Endamoeba 
parasitizing opalinid ciliates. Biol. Bull., 70:56. 

Taliaferro, W. H. and Holmes, F. O.: (1924) Endamoeba barreti, 
etc. Am. J. Hyg., 4:155. 

Tyzzer, E. E. : (1920) Amoebae of the caeca of the common fowl and 
of the turkey. J. Med. Res., 41:199. 

Volkonsky, M.: (1931) Hartmannella castellanii, etc. Arch. zool. 
exper. gen., 72:317. 


Walker, E. L.: (1908) The parasitic amoebae of the intestinal tract 

of man and other animals. J. Med. Res., 17:379. 
Wenrich, D. H. : (1936) Studies on Dientamoeba fragilis. I. Jour. 

Parasit., 22:76. 

(1937) II. Ibid., 23:183. 

(1937a) Studies on Iodamoeba butschlii with special reference 

to nuclear structure. Proc. Am. Philos. Soc, 77:183. 
(1939) Studies on Dientamoeba fragilis. III. J. Parasit., 25: 

(1940) Nuclear structure and nuclear division in the trophic 

stages of Entamoeba muris. J. Morph., 66:215. 
(1941) Observations on the food habits of Entamoeba muris 

and Entamoeba ranarum. Biol. Bull., 81:324. 

(1944) Studies on Dientamoeba fragilis. IV. J. Parasit., 


(1944a) Nuclear structure and nuclear division in Dient- 
amoeba fragilis. J. Morph., 74:467. 

Wenyon, C. M.: (1926) Protozoology. 1. London and Baltimore. 
Wermel, E.: (1925) Beitrage zur Cytologie der Amoeba hydroxena 

Entz. Arch. russ. Protist., 4:95. 
Wilber, C. G.: (1942) The cytology of Pelomyxa carolinensis. Tr. 

Am. Micr. Soc, 61:227. 
(1945) Origin and function of the protoplasmic constituents 

in Pelomyxa carolinenesis. Biol. Bull., 88:207. 

(1946) Notes on locomotion in Pelomyxa carolinensis. Tr. 

Am. Micr. Soc, 65:318. 

(1947) Concerning the correct name of the rhizopod, 

Pelomyxa carolinensis. Ibid., 66:99. 
Wilson, H. V.: (1900) Notes on a species of Pelomyxa. Am. Nat., 

Yorke, W. and Adams, A. R. D.: (1926) Observations on Entamoeba 

histolytica. I. Ann. Trop. Med. Parasit., 20:279. 

Chapter 20 
Order 4 Testacea Schultze 

THE Testacea or Thecamoeba comprise those amoeboid organ- 
isms which are enveloped by a simple shell or test, within which 
the body can be completely withdrawn. The shell has usually a single 
aperture through which pseudopodia protrude, and varies in shape 
and structure, although a chitinous or pseudochitinous membrane 
forms the basis of all. It may be thickened, as in Arcella and others, 
or composed of foreign bodies cemented together as in Difflugia, 
while in Euglypha siliceous platelets or scales are formed in the 
endoplasm and deposited in the shell. 

The cytoplasm is ordinarily differentiated into the ectoplasm and 
endoplasm. The ectoplasm is conspicuously observable at the aper- 
ture of the shell where filopodia or slender ectoplasmic lobopodia 
are produced. The endoplasm is granulated or vacuolated and con- 
tains food vacuoles, contractile vacuoles and nuclei. In some forms 
there are present regularly in the cytoplasm numerous basophilic 
granules which are known as 'chromidia' (p. 44). 

Asexual reproduction is either by longitudinal fission in the forms 
with thin tests, or by transverse division or budding, while in others 
multiple division occurs. Encystment is common. Sexual reproduc- 
tion by amoeboid or flagellate gametes has been reported in some 

The testaceans are mostly inhabitants of fresh water, but some 
live in salt water and others are semi-terrestrial, being found in 
moss or moist soil, especially peaty soil. Biology of soil-inhabiting 
forms (Volz, 1929); ecology (Hoogenraad, 1935). 

Shell simple and membranous 

Filopodia, in some anastomosing Family 1 Gromiidae 

Pseudopodia fllose, simply branched Family 2 Arcellidae (p. 476) 

Shell with foreign bodies, platelets, or scales 

With foreign bodies Family 3 Difflugiidae (p. 482) 

With platelets or scales Family 4 Euglyphidae (p. 487) 

Family 1 Gromiidae Eimer and Fickert 

These forms are frequently included in the Foraminifera by other 

Genus Gromia Dujardin (Allogromia, Rhynchogromia, Diplo- 
gromia Rhumbler). Thin test rigid or flexible, smooth or slightly 
coated with foreign bodies; spherical to elongate ellipsoid; aperture 



terminal; 1 or more nuclei; contractile vacuoles; many filopodia, 
branching and anastomosing; cytoplasm with numerous motile 
granules; fresh or salt water. Many species. 

G.fluvialis D. (Fig. 199, a). Test spherical to subspherical; smooth 
or sparsely covered with siliceous particles; yellowish cytoplasm 
fills the test; aperture not seen; a large nucleus and numerous con- 
tractile vacuoles; filopodia long, often enveloping test; 90-250/* 
long; on aquatic plants, in moss or soil. 

G. ovoidea (Rhumbler) (Fig. 199, b). In salt water. 

G. nigricans (Penard) (Fig. 199, c). Test large, circular in cross- 
section; a single nucleus; 220-400/* long; in pond water among vege- 

Genus Microgromia Hertwig and Lesser. Test small, hyaline, 
spherical or pyriform, not compressed; aperture terminal, circular; 
filopodia long straight or anastomosing, arising from a peduncle; a 
single nucleus and contractile vacuole; solitary or grouped. Morphol- 
ogy (Valkanov, 1930). 

M. socialis (Archer) (Fig. 199, d). Cytoplasm bluish; contractile 
vacuole near aperture; filopodia arise from a peduncle, attenuate, 
branching, anastomosing; often numerous individuals are grouped; 
multiplication by fission and also by swarmers; 25-35/* in diameter; 
among vegetation in fresh water. 

Genus Microcometes Cienkowski. Body globular, enclosed within 
a transparent, delicate, light yellowish and pliable envelope with 
3-5 apertures, through which long branching filopodia extend; body 
protoplasm occupies about 1/2 the space of envelope; 1-2 contrac- 
tile vacuoles ; fresh w ater. 

M. paludosa C. (Fig. 199, e). About 16-17/* in diameter; fresh 
water among algae (Valkanov, 1931; Jepps, 1934). 

Genus Artodiscus Penard. Body globular, plastic; covered by 
envelope containing small grains of various kinds; nucleus eccentric; 
a few pseudopodia extend through pores of the envelope; movement 
very rapid ; fresh water. 

A. saltans P. (Fig. 199,/). 18-23/* in diameter; fresh water. 

Genus Lieberkiihnia Claparede and Lachmann. Test ovoidal or 
spherical, with or without attached foreign particles; aperture 
usually single, lateral or subterminal; one or more nuclei; many con- 
tractile vacuoles; pseudopodia formed from a long peduncle, reticu- 
late, often enveloping test; fresh or salt water. 

L. wagneri C. and L. (Fig. 200, a). Spheroidal; aperture subtermi- 
nal, oblique, flexible; cytoplasm slightly yellowish, fills the test; 
80-150 vesicular nuclei; nuclei 6/* in diameter; many contractile vac- 



Fig. 199. a, Gromia fluvialis, X120 (Dujardin); b, (?. ovoidea, X50 
(Schultze); c, (r. nigricans, X200 (Cash and Wailes); d, Microgromia 
socialis, X170 (Cash); e, Microcometes paludosa, X670? (Penard); 
f, Artodiscus saltans, X670 (Penard); g, Schultzella diffluens, X120 



uoles; pseudopodia long, anastomosing; 60-1 60m long; among algae 
in fresh and salt water. 

Genus Diplophrys Barker. Test thin, spherical; 2 apertures, one 
at each pole; cytoplasm colorless; a single nucleus; several contrac- 
tile vacuoles; filo podia radiating. One species. 

D. archeri B. (Fig. 200, b). With 1-3 colored oil droplets; pseu- 
dopodia highly attenuate, radiating, straight or branched; multi- 
plication into 2 or 4 daughter individuals; solitary or in groups; 
diameter 8-20/z; on submerged plants in fresh water. 

Fig. 200. a, Lieberkuhnia ivagneri, X160 (Verworn); b, Diplophrys 
archeri, X930 (Hertwig and Lesser); c, Lecythium hyalinum, X330 
(Cash and Wailes); d, Myxotheca arenilega, X70 (Schaudinn); e, Dac- 
tylosaccus vermiformis, Xl5 (Rhumbler); f, Boderia turneri (Wright). 

Genus Lecythium Hertwig and Lesser. Test thin, flexible, color- 
less; aperture elastic, terminal; colorless cytoplasm fills the test; 
large nucleus posterior; numerous filopodia long, branching, not 
anastomosing; fresh water. 

L. hyalinum (Ehrenberg) (Fig. 200, c). Spheroidal; aperture cir- 
cular with a short flexible neck; a single contractile vacuole; diame- 
ter 20-45/z ; in submerged vegetation. 


Genus Schultzella Rhumbler. Test thin, delicate, difficult to 
recognize in life, easily broken at any point for formation of pseudo- 
podia which branch and anastomose; irregularly rounded; without 
foreign material; salt water. 

S. diffluens (Grubler) (Fig. 199, g). Cytoplasm finely granulated; 
opaque, colorless; with oil droplets, vacuoles and numerous small 
nuclei ; up to 220/j. in diameter. 

Genus Myxotheca Schaudinn. Amoeboid; spherical or hemi- 
spherical, being flattened on the attached surface; a thin pseudo- 
chitinous test with foreign bodies, especially sand grains; pseudo- 
podia anastomosing; salt water. Nucleus (Foyn, 1936). 

M. arenilega S. (Fig. 200, d). Test yellow, with loosely attached 
foreign bodies; cytoplasm bright red due to the presence of highly 
refractile granules; 1-2 nuclei, 39-75ju in diameter; body diameter 

Genus Dactylosaccus Rhumbler. Test sausage-shape and vari- 
ously twisted; pseudo podia filiform, anastomosing; salt water. 

D. vermiformis R. (Fig. 200, e). Test smooth; pseudo podia rise 
from small finger-like projections; 1-2 nuclei; body 4 mm. by 340m ; 
salt water. 

Genus Boderia Wright. Body form changeable; often spherical, 
but usually flattened and angular; filopodia long; test extremely 
delicate, colorless; salt water. 

B. turneri W. (Fig. 200, /). Body brown to orange; active cyto- 
plasmic movement; 1-10 nuclei ; multiple division(?) ; 1.56-6.25 mm. 
in diameter; in shallow water. 

Family 2 Arcellidae Schultze 

Genus Arcella Ehrenberg. Test transparent, chitinous, densely 
punctated; colorless to brown (when old); in front view circular, 
angular, or stellate; in profile plano-convex or semicircular; vari- 
ously ornamented; aperture circular, central, inverted like a funnel; 
protoplasmic body does not fill the test and connected with the latter 
by many ectoplasmic strands; slender lobopodia, few, digitate, sim- 
ple or branched; 2 or more nuclei; several contractile vacuoles; fresh 
water. Numerous species. Taxonomy and morphology (Deflandre, 
1928); variation and heredity (Jollos, 1924). 

A. vulgaris E. (Fig. 201, a, b). Height of test about 1/2 the diame- 
ter; dome of hemispherical test evenly convex; aperture circular, 
central; colorless, yellow, or brown; protoplasmic body conforms 
with the shape of, but does not fill, the test; lobopodia hyaline; 2 
vesicular nuclei; several contractile vacuoles; test 30-100/x in dia- 



meter; in the ooze and vegetation in stagnant water and also in soil. 
Of several varieties, two may be mentioned; var. angulosa (Perty), 
test smaller, 30-40/i in diameter, faceted, forming a 5- to 8-sided 
figure, with obtuse angles; var. gibbosa (Penard), test gibbous, sur- 
face pitted with circular depressions of uniform dimensions: 45-50xi 
up to 100/z in diameter. 


Fig. 201. a, b, Arcella vulgaris, X170; X230 (Leidy); c, A. discoides, 
X170 (Leidy); d, A. mitrata, X140 (Leidy); e, f, A. catinus. X 170 (Cash); 
g-i, A. dentata, X170 (Leidy); j, k, A. artocrea, X170 (Leidy). 

A. discoides E. (Fig. 201, c). Test circular in front view, plano- 
convex in profile; diameter about 3-4 times the height; test color- 
ation and body structure similar to those of A. vulgaris; test 70- 
260/t in diameter; in fresh water. 

A. mitrata Leidy (Fig. 201, d). Test balloon-shaped or polyhedral; 
height exceeds diameter of base; aperture circular, crenulated and 
usually evarted within inverted funnel; protoplasmic body sphe- 
roidal, with 'neck' to aperture and cytoplasmic strands to test; 6 or 
more slender lobopodia; test 100-145/* high, 100-152/* in diameter; 
in fresh water among vegetation. 

A. catinus Penard (Fig. 201, e, /). Test oval or quadrate, not 
circular, in front view; aperture oval; dome compressed; lateral 
margin with 6 or 8 facets; test 100-120/i in diameter and about 
45/i high; fresh water among vegetation. 

A. dentata Ehrenberg (Fig. 201, g-i). Test circular and dentate 



in front view, crown-like in profile; diameter more than twice the 
height; aperture circular, large; colorless to brown; about 95^ in 
diameter, aperture 30/x in diameter; 15-17 spines; in the ooze of 
freshwater ponds. 

A. artocrea Leidy (Fig. 201, j, k). Heightof test 1/4-1/2 the diame- 
ter; dome convex; surface mammillated or pitted; border of test 
everted and rising 1/4-1/2 the height of test; about 175/z in diame- 
ter; fresh water. 

Fig. 202, a, b, Pyxidicula operculata, X800 (Penard); c, Pseudochlamys 
patella, X330 (Cash); d, e, Difflugiella apicidata, X270 (Cash); f, Crypto- 
difflugia oviformis, X320 (Cash); g, Lesquereusia spiralis, X270 (West); 
h, Hyalosphenia papilio, X330 (Leidy); i, Corycia coronata, X170 
(Penard); j, Pamphagus mutabilis, X330 (Leidy); k, Plagiophrys parvi- 
punctata, X330 (Penard). 

Genus Pyxidicula Ehrenberg. Test patelliform; rigid, transparent, 
punctate; aperture circular, almost the entire diameter of test; 
cytoplasm similar to that of Arcella; a single nucleus; 1 or more 
contractile vacuoles; fresh water. 

P. operculata (Agardh) (Fig. 202, a, b). Test smooth, colorless to 
brown; a single vesicular nucleus; pseudopodia short, lobose or 
digitate; 20/x in diameter; on vegetation. 


Genus Pseudochlamys Claparede and Lachmann. Test discoid, 
flexible when young; body with a central nucleus and several con- 
tractile vacuoles. 

P. patella C. and L. (Fig. 202, c). Young test hyaline, older one 
rigid and brown; often rolled up like a scroll; a short finger-like 
pseudopodium between folds; 40-45ai in diameter; in fresh water 
among vegetation, in moss and soil. 

Genus Difflugiella Cash. Test ovoid, not compressed, flexible 
and transparent membrane; colorless cytoplasm fills the test, usually 
with chlorophyllous food material; median pseudopodia lobate or 
digitate with aciculate ends, while lateral pseudopods long, straight, 
and fine, tapering to a point; fresh water. One species. 

D. apiculata C. (Fig. 202, d, e). About 40^ by 28/z; among vege- 

Genus Cryptodifflugia Penard. Small test j^ellowish to brownish; 
Difflugia-like in general appearance, compressed; with or without 
foreign bodies; pseudopodia long, acutely pointed; fresh water. 

C. ovijormis P. (Fig. 202, /). Test ovoid; without foreign bodies; 
crown hemispherical; aperture truncate; cytoplasm with chloro- 
phyllous food particles; 16-20/x by 12-15/x; in marshy soil. 

Genus Lesquereusia Schlumberger. Test compressed, oval or 
globular in profile, narrowed at bent back; semispiral in appearance; 
with curved or comma-shaped rods or with sand-grains (in one 
species); body does not fill up the test; pseudopodia simple or 
branched ; fresh water. 

L. spiralis (Ehrenberg) (Fig. 202, g). Aperture circular; border 
distinct; cytoplasm appears pale yellow; a single nucleus; 96-188/x 
by 68-1 14/i ; in marsh water. 

Genus Hyalosphenia Stein. Test ovoid or pyriform; aperture end 
convex; homogeneous and hyaline, mostly compressed; crown uni- 
formly arched; protoplasm partly filling the test; several blunt 
pseudopodia simple or digitate. Several species. 

H. papilio Leidy (Fig. 202, h). Test yellowish; transparent; 
pyriform or oblong in front view ; a minute pore on each side of crown 
and sometimes one also in center; aperture convex; in narrow lateral 
view, elongate pyriform, aperture a shallow notch; with chloro- 
phyllous particles and oil globules; 110-140/* long; in fresh water 
among vegetation. 

Genus Corycia Dujardin. Envelope extremely pliable, open at 
base, but when closed, sack-like; envelope changes its shape with 
movement and contraction of body; with or without spinous pro- 


C. coronata Penard (Fig. 202, i). 6-12 spines; 140/* in diameter; 
in moss. 

Genus Pamphagus Bailey. Test hyaline membranous, flexible; 
aperture small; body fills the envelope completely; spherical nuc- 
leus large; contractile vacuoles; filo podia long, delicate, branching, 
but not anastomosing; fresh water. Species (Hoogenraad, 1936). 

P. mutabilis B. (Fig. 202, j). Envelope 40-100/* by 28-68/*. 

Genus Plagiophrys Claparede and Lachmann. Envelope thin, 
hyaline, changeable with body form; usually elongate-oval with 
rounded posterior end; narrowed at other half; envelope finely 
punctated with a few small plates; aperture round; cytoplasm 
clear; nucleus large; pseudopods straight filopodia, sometimes 
branching ; fresh water. 

P. parvipunctata Penard (Fig. 202, k). Envelope 50/* long. 

Genus Leptochlamys West. Test ovoid, thin transparent chitinous 
membrane, circular in optical section; aperture end slightly ex- 
panded with a short neck; aperture circular, often oblique; body 
fills test; without vacuoles; pseudo podium short, broadly expanded 
and sometimes cordate; fresh water. 

L. ampullacea W. (Fig. 203, a). Nucleus large, posterior; with 
green or brown food particles; test 45-55/* by 36-40/* in diameter; 
aperture 15-17/*; among algae. 

Genus Chlamydophrys Cienkowski. Test rigid, circular in cross- 
section; aperture often on drawn-out neck; body fills the test; zonal 
differentiation of cytoplasm distinct; nucleus vesicular; refractile 
waste granules; pseudopodia branching; fresh water or coprozoic. 
Species (Belaf, 1926); plasmogamy and division (Belar, 1926). 

C. stercorea C. (Fig. 203, k). Test 18-20/* by 12-15/*; mature cysts 
yellowish brown, 12-15/* in diameter; multiplication by budding; 
coprozoic and fresh water. 

Genus Cochliopodium Hertwig and Lesser. Test thin, flexible, 
expansible and contractile; with or without extremely fine hair-like 
processes; pseudopodia blunt or pointed, but not acicular. Several 

C. bilimbosum (Auerbach) (Fig. 203, b). Test hemispherical; pseu- 
dopodia conical with pointed ends; test 24-56/* in diameter; fresh 
water among algae. 

Genus Amphizonella Greeff. Test membranous with a double 
marginal contour; inner membrane smooth, well-defined; outer 
serrulate; aperture inverted; a single nucleus; pseudopodia blunt, 
digitate, and divergent. 

A. violacea G. (Fig. 203, c). Test patelliform, violet-tinted; with 



chlorophyllous corpuscles and grains; sluggish; average diameter 
160/z; fresh water. 

Genus Zonomyxa Ntisslin. Test rounded pyriform, flexible, 
chitinous, violet-colored; endoplasm vacuolated, with chlorophyl- 

Fig. 203. a, Leptochlamys ampullacea, X330 (West); b, Cochliopodium 
bilimbosum, X670 (Leidy); c, Amphizonella violacea, X270 (Greeff); 
d, Zonomyxa violacea, X200 (Penard); e, f, Microcorycia flava, X240 
(Wailes); g, h, Parmulina cyathus, X500 (Penard); i, Diplochlamys leidyi 
X270 (Brown); j, Capsellina timida, X270 (Wailes); k, Chlamydophrys 
stercorea, X670 (Wenyon). 

lous particles; several nuclei; pseudo podia simple, not digitate; fresh 

Z. violacea N. (Fig. 203, d). A single lobular pseudo podium with 
acuminate end; 4 nuclei; diameter 140-160/u; actively motile forms 
250/z or longer; among sphagnum. 

Genus Microcorycia Cockerell. Test discoidal or hemispherical,. 


flexible, with a diaphanous continuation or fringe around periphery, 
being folded together or completely closed; crown of test with cir- 
cular or radial ridges; body does not fill the test; 1-2 nuclei; pseu- 
dopodia lobular or digitate; fresh water. A few species. 

M. flava (Greeff) (Fig. 203, e, /). Test yellowish brown; crown 
with few small foreign bodies; endoplasm with yellowish brown 
granules; 2 nuclei; contractile vacuoles; diameter 80-100/*; young 
individuals as small as 20ju; in moss. 

Genus Parmulina Penard. Test ovoid, chitinoid with foreign 
bodies; aperture may be closed; a single nucleus; 1 or more contrac- 
tile vacuoles; fresh water. A few species. 

P. cyathus P. (Fig. 203, g, h). Test small, flexible; ovoid in aper- 
ture view, semicircular in profile; aperture a long, narrow slit when 
test is closed, but circular or elliptical when opened; 40-55/* long; 
in moss. 

Genus Capsellina Penard. Test hyaline, ovoid, membranous; 
with or without a second outer covering; aperture long slit; a single 
nucleus; 1 or more contractile vacuoles; filose pseudopodia; fresh 

C. timida Brown (Fig. 203, j). Small, ovoid; elliptical in cross- 
section; with many oil (?) globules; filo podium; 34/* by 25/*; in moss. 

Genus Diplochlamys Greeff. Test hemispherical or cup-shaped, 
flexible with a double envelope; inner envelope a membranous sack 
with an elastic aperture; outer envelope with loosely attached for- 
eign bodies; aperture large; nuclei up to 100; pseudopodia few, 
short, digitate or pointed; fresh water. Several species. 

D. leidyi G. (Fig. 203, i). Test dark gray; inner envelope project- 
ing beyond outer aperture; nuclei up to 20 in number; diameter 

Family 3 Difflugiidae Taranek 

Genus Difflugia Leclerc. Test variable in shape, but generally 
circular in cross-section; composed of cemented quartz-sand, di- 
atoms, and other foreign bodies; aperture terminal; often with 
zoochlorellae; cytoplasmic body almost fills the test; a single nu- 
cleus; many contractile vacuoles; pseudopodia cylindrical, simple 
or branching; end rounded or pointed; fresh water, woodland soil, 

D. oblonga Ehrenberg (D. pyriformis Perty) (Fig. 204, a). Test 
pyriform, flask-shaped, or ovoid; neck variable in length; fundus 
rounded, with occasionally 1-3 conical processes; aperture terminal, 
typically circular; test composed of angular sand-grains, diatoms; 
bright green with chlorophyllous bodies; 60-580/* by 40-240/*; in 



the ooze of fresh water ponds, ditches and bogs; also in moist soil. 
Several varieties. 

D. urceolata Carter (Fig. 204, b). A large ovoid, rotund test, with 
a short neck and a rim around aperture; 200-230^ by 150-200^: 
in ditches, ponds, sphagnous swamps, etc. 

Fig. 204. a, Difflugia oblonga, X130 (Cash); b, D. urceolata, X130 
(Leidy); c, d, D. arcula, X170 (Leidy); e, D. lobostoma, X130 (Leidy); 
f, D. constricta, X200 (Cash); g, Centropyxis aculeata, X200 (Cash); 
h, Campuscus cornutus, X170 (Leidy); i, Cucurbitella mespiliformis, 
X200 (Wailes). 

D. arcula Leidy (Fig. 204, c, d). Test hemispherical, base slightly 
concave, but not invaginated ; aperture triangular, central, trilobed ; 
test yellowish with scattered sand-grains or diatoms; diameter 
100-140ju; in sphagnous swamp, moss, soil, etc. 

D. lobostoma L. (Fig. 204, e). Test ovoid to subspherical; aperture 
terminal; with 3-6 lobes; test usually composed of sand-grains, 
rarely with diatoms; endoplasm colorless or greenish; diameter 
80-120ju; in fresh water. Sexual fusion and life cycle (Goette, 1916). 

D. constricta (Ehrenberg) (Fig. 204, /). Test laterally ovoid, 
fundus more or less prolonged obliquely upward, rounded, and sim- 
ple or provided with spines; soil forms generally spineless; aperture 
antero -inferior, large, circular or oval and its edge inverted; test 
composed of quartz grains; colorless to brown; cytoplasm colorless; 
80-340/1 long; in the ooze of ponds and in soil. 


D. corona Wallich. Test ovoid to spheroid, circular in cross- 
section; crown broadly rounded, with a variable number of spines, 
aperture more or less convex in profile, central and its border mul- 
tidentate or multilobate; test with fine sand-grains, opaque; cyto- 
plasm colorless; pseudopodia numerous, long, branching or bifur- 
cating; 180-230^ by about 150^; in fresh water. Genetics (Jennings, 
1916, 1937). 

Genus Centropyxis Stein. Test circular, ovoid, or discoid; aper- 
ture eccentric, circular or ovoidal, often with a lobate border; with 
or without spines; cytoplasm colorless; pseudopodia digitate; fresh 
water. Species (Deflandre, 1929). 

C. aculeata S. (Fig. 204, g). Test variable in contour and size; with 
4-6 spines; opaque or semitransparent ; with fine sand-grains or 
diatom shells; pseudopodia sometimes knotted or branching; when 
encysted, the body assumes a spherical form in wider part of test; 
granulated, colorless or with green globules; diameter 100-150)u; 
aperture 50-60/z in diameter. 

Genus Campascus Leidy. Test retort-shaped with curved neck, 
rounded triangular in cross-section; aperture circular, oblique, with 
a thin transparent discoid collar; nucleus large; 1 or more contrac- 
tile vacuoles; body does not fill the test; fresh water. 

C. cornutus L. (Fig. 204, h). Test pale-yellow, retort-form; with 
a covering of small sand particles; triangular in cross-section; a 
single nucleus and contractile vacuole; filo podia straight; 110-140/n 
long; aperture 24-28ju in diameter; in the ooze of mountain lakes. 

Genus Cucurbitella Penard. Test ovoid with sand-grains, not 
compressed; aperture terminal, circular, surrounded by a 4-lobed 
annular collar; cytoplasm grayish, with zoochlorellae; nucleus 
large; 1 to many contractile vacuoles; pseudopodia numerous, 
digitate; fresh water. 

C. mespiliformis P. (Fig. 204, i). 115-140/* long; diameter 80- 
105ju; in the ooze or on vegetaiton in ponds and ditches. 

Genus Plagiopyxis Penard. Test subcircular in front view; ovoid 
in profile; aperture linear or lunate; cytoplasm gray, with a single 
nucleus and a contractile vacuole; fresh water. 

P. callida P. (Fig. 205, a). Test gray, yellowish, or brown; large 
nucleus vesicular; pseudopodia numerous, radiating, short, pointed 
or palmate; diameter 55-135/x; in vegetation. 

Genus Pontigulasia Rhumbler. Test similar to that of Difflugia, 
but with a constriction of neck and internally a diaphragm made of 
the same substances as those of the test. 

P. vas (Leidy) (Fig. 205, b). Round or ovoid test; constriction 



deep and well-marked; with sand-grains and other particles; aper- 
ture terminal; 125-170/z long; fresh water ponds. Stump (1943) 
made a study of the nuclear division of the organism. During meta- 
phase 8-12 "chromosomes" form a well-defined equatorial plate; 
average time for completion of the division was found to be 80 min- 

Fig. 205. a, Plagiopyxis callida, X200 (Wailes); b, Pontigulasia vas 
X200 (Cash); c, Phnjganella acropodia, X190 (Cash); d, Bullinula 
indica, X130 (Wailes); e, f, Heleopera petricola, X190 (Cash); g, Nadi- 
nella tenella, X400 (Penard); h, Frenzelina reniformis, X600 (Penard); 
i, Amphitrema flavum, X360 (Cash and Wailes); j, Pseudodifflugia gracilis, 
X330 (Cash); k, Diaphoropodon mobile, X270 (Cash and Wailes); 1, m, 
Clypeolina marginata, X330 (Cash and Wailes). 

Genus Phryganella Penard. Test spheroidal or ovoid, with sand- 
grains and minute diatom shells; aperture terminal, round; pseudo- 
podia drawn out to a point; fresh water. 

P. acropodia (Hertwig and Lesser) (Fig. 205, c). Test circular in 


aperture view; hemispherical in profile; yellowish or brownish, 
semi-transparent, and covered with sand-grains and scales; in front 
view sharply pointed pseudopodia radiating; colorless endoplasm 
usually with chlorophyllous bodies; 30-50/i in diameter. 

Genus Bullinula Penard. Test ellipsoidal, flattened on one face, 
with silicious plates; on the flattened surface, » -shaped aperture; 
a single nucleus; pseudopodia digitate or spatulate, simple or 
branched; fresh water. 

B. indica P. (Fig. 205, d). Test dark brown; 120-250/z in diameter. 
Distribution and morphology (Hoogenraad, 1933). 

Genus Heleopera Leidy. Test variously colored; fundus hemi- 
spherical, with sand-grains; surface covered with amorphous scales, 
often overlapping; aperture truncate, narrow, elliptic notched in 
narrow lateral view; a single nucleus; pseudopodia variable in num- 
ber, thin digitate or branching; fresh water. Several species. 

H. petricola L. (Fig. 205, e, /). Test variable in size and color, 
strongly compressed; fundus rough with sand-grains of various 
sizes; aperture linear or elliptic, convex in front view; pseudopodia 
slender, branching; 80-lOOju long; in boggy places. 

Genus Averintzia Schouteden. Test similar to that of Heleopera, 
but small aperture elliptical; test thickened around aperture; fresh 

A. cyclostoma (Penard). Test dark violet, with sand-grains of dif- 
ferent sizes; elliptical in cross-section; pseudopodia unobserved; 135- 
180^ long; in sphagnum and aquatic plants. 

Genus Nadinella Penard. Test chitinous, thin, hyaline, with for- 
eign bodies and collar around aperture; filo podia; fresh water. 

N. tenella P. (Fig. 205, g). 50-55/x long; fresh water lakes. 

Genus Frenzelina Penard. Two envelopes, outer envelope hemi- 
spherical, thin, rigid, covered with siliceous particles; inner envelope 
round or ovoid, drawn out at aperture, thin, hyaline and covering 
the body closely; aperture round, through which a part of body with 
its often branching straight filo pods extends; cytoplasm with dia- 
toms, etc.; a nucleus and a contractile vacuole; fresh water. 

F. reniformis P. (Fig. 205, h). Outer envelope 26-30/x in diameter; 
fresh water lakes. 

Genus Amphitrema Archer. Test ovoid, symmetrical, compressed; 
composed of a transparent membrane, with or without adherent 
foreign bodies; 2 apertures at opposite poles; with zoochlorellae; 
nucleus central; 1 to several contractile vacuoles; straight filo podia, 
sparsely branched, radiating; fresh water. Several species. 

A. flavum A. (Fig. 205, i). Test brown, cylindrical with equally 


rounded ends in front view; elliptical in profile; ovoid with a small 
central oval aperture in end view; 45-77/* by 23-45/*; in sphagnum. 

Genus Pseudodifflugia Schlumberger. Test ovoid, usually rigid, 
with foreign bodies; circular or elliptical in cross-section; aperture 
terminal; granulated cytoplasm colorless or greyish; nucleus poster- 
ior; a contractile vacuole; filo podia long, straight or branching; fresh 
water. Several species. 

P. gracilis S. (Fig. 205, j). Test yellowish or brownish; subspheri- 
cal, with sand-grains; aperture without neck; 20-65/* long. 

Genus Diaphoropodon Archer. Test ovoid, flexible, with minute 
foreign bodies and a thick covering of hyaline hair-like projections; 
pseudopodia long, filose, branching; fresh water. 

D. mobile A. (Fig. 205, k). Test brown; of various shapes; aperture 
terminal; body does not fill the test; nucleus large; 1-2 contractile 
vacuoles; 60-120/* long; projections 8-10/* long; in vegetation. 

Genus Clypeolina Penard. Test ovoid, compressed, formed of a 
double envelope; outer envelope composed of 2 valves with scales 
and particles; inner envelope a membranous sack; long filo podia, 
often branching; fresh water. 

C. marginata P. (Fig. 205, I, m). Outer test-valves }^ellow to dark 
brown; lenticular in cross-section; wide terminal aperture; endo- 
plasm with many small globules; a single nucleus and contractile 
vacuole; 80-150/* long. 

Family 4 Euglyphidae Wallich 

Genus Euglypha Dujardin (Pareuglypha Penard). Test hyaline, 
ovoid, composed of circular, oval, or scutiform siliceous imbricated 
scales, arranged in longitudinal rows; aperture bordered with regu- 
larly arranged denticulate scales; usually with spines; 1-2 nuclei 
large, placed centrally; filopodia dichotomously branched; contrac- 
tile vacuoles; fresh water. Numerous species. Division and encyst- 
ment (Ivanic, 1934). 

E. acanthophora (Ehrenberg) (E. alveolata D.) (Fig. 74). Test 
ovoid, or slightly elongate; 3-7 scales protruding around the circular 
aperture; scales elliptical; body almost fills the test; 50-100/* long. 

E. cristata Leidy (Fig. 206, a). Test small, elongate with a long 
neck, fundus with 3-8 spines; scales oval; aperture circular, bordered 
by a single row of 5-6 denticulate scales; cytoplasm colorless; nucleus 
posterior; reserve scales are said to be collected around the exterior 
of aperture, unlike other species in which they are kept within the 
cytoplasm; 30-70/* long; 12-23/* in diameter; aperture 6-12/*; scales 
4.5-9.5/* by 2.5-6.5/*; spines 10-15/* long. 



E. mucronata L. (Fig. 206, b). Test large; fundus conical, with 
1-2 terminal spines (12-44^ long); aperture circular, bordered by a 
single row of 6-8 denticulate scales; 100-150^ long, diameter 30-60^; 
aperture 15-20ju in diameter. 

Fig. 206. a, Euglypha cristata, X330 (Wailes); b, E. mucronata, X330 
(Wailes); c, Paulinella chromatophora, X1000 (Wailes); d, Cyphoderia 
ampulla, X200 (Cash); e, f, Corythion pulchellum, X350 (Wailes). 

Genus Paulinella Lauterborn. Test small ovoid, not compressed; 
with siliceous scales in alternating transverse rows; aperture ter- 
minal ; body does not fill the test completely ; nucleus posterior; among 
vegetation in fresh or brackish water. 

P. chromatophora L. (Fig. 206, c). Scales arranged in 11-12 rows; 
with 1-2 curved algal symbionts; no food particles; a single con- 
tractile vacuole; 20-32ju long; 14-23^ in diameter. 

Genus Cyphoderia Schlumberger. Test retort-shaped; colorless to 
yellow; made up of a thin chitinous membrane, covered with discs 
or scales; aperture terminal, oblique, circular; body does not fill the 
test completely; nucleus large, posterior; pseudo podia, few, long 
filose, simple or branched; fresh water (Husnot, 1943). 

C. ampulla (Ehrenberg) (Fig. 206, d). Test usually yellow, trans- 
lucent, composed of discs, arranged in diagonal rows; circular in 



cross-section; aperture circular; cytoplasm gray, with many granules 
and food particles; 2 contractile vacuoles; 60-200/* long; diameter 
30-70/*. Several varieties. 

Genus Trinema Dujardin. Test small, hyaline, ovoid, compressed 
anteriorly, with circular siliceous scales; aperture circular, oblique, 
invaginate; nucleus posterior; filopodia not branched; fresh water in 

T. enchelys (Ehrenberg) (Fig. 207, a). 1-2 contractile vacuoles; 

Fig. 207. a, Trinema enchelys, X330 (Wailes); b, Placocista spinosa, 
X200 (Wailes); c, Assulina seminulum, X400 (Wailes); d, Nebela collaris, 
X200 (Cash); e, Quadrula symmetrica, X200 (Gash); f, Sphenoderia 
lenta, X330 (Leidy). 

pseudo podia attenuate, radiating; 30-100/z long; 15-60/x wide; scales 
4-12/x in diameter. 

T. lineare Penard (Fig. 79). Test transparent; scales indistinct; 
about 35/x by 17/t; filopodia. Sexual fusion (Dunkerly, 1923) (p. 183). 

Genus Corythion Taranek. Test small, hyaline, composed of small 
oval siliceous plates; compressed; elliptical in cross-section; aperture 
subterminal, ventral or oblique, and circular or oval; numerous 
filopodia; fresh water. 

C. pulchellum Penard (Fig. 206, e, /). Aperture lenticular; cyto- 
plasm colorless; 2-3 contractile vacuoles; 25-35/z by 15-20/z; aper- 
ture 7-1 0/x by 3-4/x. 

Genus Placocista Leidy. Test ovoid, hyaline, compressed; len- 
ticular in cross-section; with oval or subcircular siliceous scales; 
aperture wide, linear, with flexible undulate borders; nucleus large, 


posterior; often with zoochlorellae; filo podia branching and man}', 
generally arising from a protruded portion of cytoplasm; fresh 

P. spinosa (Carter) (Fig. 207, b). Margin of test with spines, 
either singly or in pairs; 116-174/z by 70-100^; in sphagnum. 

Genus Assulina Ehrenberg. Test colorless or brown; ovoid; with 
elliptical scales, arranged in diagonal rows; aperture oval, terminal 
bordered by a thin chitinous dentate membrane; nucleus posterior; 
contractile vacuoles; filo podia divergent, sometimes branching; fresh 

A. seminulum (E.) (Fig. 207, c). Body does not fill the test; with 
numerous food particles; pseudo podia few, straight, divergent, 
slender, seldom branched; 60-150/x by 50-75^; in sphagnum. 

Genus Nebela Leidy. Test thin, ovate or pyriform; with circular 
or oval platelets of uniform or various sizes; highly irregular; endo- 
plasm with oil globules; nucleus posterior; body does not fill the 
test, and is connected with the latter by many ectoplasmic strands 
at fundus end; pseudo podia blunt, rarely branched; fresh water. 
Numerous species. Taxonomy (Jung, 1942a). 

N. collaris (Ehrenberg) (Fig. 207, d). Test pyriform, fundus obtuse 
in profile; aperture without any notch; endoplasm with chlorophyl- 
lous food particles; pseudopodia digitate, short, usually 3-6 in num- 
ber: about 130m by 85-90/*: in marshes among sphagnum. Feeding 
habit, binary fission and plasmogamy (MacKinlay, 1936). 

Genus Quadrula Schulze. Test pyriform, hemispherical, or dis- 
coidal; with quadrangular siliceous or calcareous platelets, arranged 
generally in oblique series, not overlapping; a single nucleus; body 
and pseudopodia similar to those of Difflugia; fresh water. 

Q. symmetrica (Wallich) (Fig. 207, e). Compressed, smaller plate- 
lets near aperture; cytoplasm very clear, with chlorophyllous gran- 
ules; 3-5 pseudopodia digitate; nucleus posterior; 80-140/z by 40- 
96/*; in sphagnum. 

Genus Sphenoderia Schlumberger. Test globular or oval, some- 
times slightly compressed; hyaline, membranous, with a short broad 
neck, and a wide elliptical aperture; scales circular, oval, or hexag- 
onal, arranged in alternating series; cytoplasm colorless; 1-2 con- 
tractile vacuoles; filo podia, fine, branching; fresh water. 

S. lenta S. (Fig. 207, /). Hyaline test ovoid or globular; scales cir- 
cular or broadly oval; aperture terminal, surrounded by a thin chi- 
tinous collar, one side inclined inwards; nucleus large; cytoplasm 
colorless; 2 contractile vacuoles; 30-64/* by 20-46/*; aperture 10-22/* 
in diameter. 



Belar, K.: (1921) Untersuchungen ueber Thecamoeben der 

Chlamydophrys-Gmppe. Arch. Protist., 43:287. 
Breuer, R. : (1916) Fortpflanzung und biologische Erscheinungen 

einer Chlamydophrys-Form auf Agarkulturen. Ibid., 37:65. 
Cash, J.: (1905) The British freshwater Rhizopoda and Heliozoa. 1. 

(1909) 2. 

and Wailes, G. H.: (1915) 3. 

(1918) 4. 

Deflandre, G.: (1928) Le genre Arcella. Arch. Protist., 64:152. 

(1929) Le genre Centropyxis. Ibid., 67:322. 

Dunkerly, J. S.: (1923) Encystation and reserve food formation 

in Trinema lineare. Tr. Roy. Soc. Edinburgh, 53:297. 
Foyn, B.: (1936) Ueber die Kernverhaltnisse der Foraminifere 

Myxotheca arelilega. Arch. Protist., 87:272. 
Goette, A.: (1916) Ueber die Lebenscyclus von Difflugia lobostoma. 

Ibid., 37:93. 
Hegner, R. W.: (1920) The relation between nuclear number, 

chromatin mass, etc. J. Exper. Zool., 30: 1. 
Hoogenraad, H. R. : (1933) Einige Beobachtungen an Bullinula 

indica. Arch. Protist., 79:119. 
(1935) Studien ueber die sphagnicolen Rhizopoden der 

niederlandischen Fauna. Ibid., 84:1. 

(1936) Was ist Pamphagus mutabilis Bailey? Ibid., 87:417. 

Husnot, P. (1943) Contribution a l'etude des Rhizopodes de Bre- 

tagne. Les Cyphoderia, etc. 143 pp. Paris. 
Ivanic, M.: (1934) Ueber die gewohnliche Zweiteilung, multiple 

Teilung und Encystierung bei zwei Euglypha-Arten. Arch. 

Protist., 82:363. 
Jennings, H. S.: (1916) Heredity, variation and the results of se- 
lection in the uniparental reproduction of Difflugia corona. 

Genetics, 1:407. 
(1937) Formation, inheritance and variation of the teeth in 

Difflugia corona. J. Exper. Zool., 77:287. 
Jepps, Margaret W. : (1934) On Kibisidytes marinus, etc. Quart. J. 

Micr. Sc, 77:121. 
Jollos, V.: (1924) Untersuchungen ueber Variabilitat und Ver- 

erbung bei Arcellen. Arch. Protist., 49:307. 
Jung, W.: (1942) Sudchilenische Thekamoeben. Ibid., 95:253. 
(1942a) Illustrierte Thekamoeben-Bestimmungstabellen. I. 

Ibid., 95:357. 
Leidy, J.: (1879) Freshwater Rhizopods of North America. Rep. 

U. S. Geol. Surv. Terr., 12. 
MacKinlay, Rose B.: (1936) Observations on Nebela collaris, etc. 

J. Roy. Micr. Soc, 56:307. 
Penard, E. : (1890) Etudes sur les rhizopods d'eau douce. Mem. soc. 

phys. hist, nat., Geneva, 31:1. 

(1902) Faune rhizopodique du bassin du Leman. Geneva. 

(1905) Sarcodines des Grands Lacs. Geneva. 


Stump, A. B.: (1943) Mitosis and cell division in Pontigulasia vas. 

J. El. Mitch. Sc. Soc, 59:14. 
Valkanov, A.: (1930) Morphologie und Karyologie cer Micro- 

gromia elegantula. Arch. Protist., 71:241. 
(1931) Beitrag zur Morphologie und Karyologie der Micro- 

cometes paludosa. Ibid., 73:367. 
Volz, P.: (1929) Studien zur Biologie der bodenbewohnenden 

Thekamoeben. Ibid., 69:348. 

Chapter 21 
Order 5 Foraminifera d'Orbigny 

THE Foraminifera are comparatively large Protozoa, living al- 
most exclusively in the sea. They were very abundant in geo- 
logic times and the fossil forms are important in applied geology 
(p. 10). The majority live on ocean bottom, moving about slug- 
gishly over the mud and ooze by means of their pseudopodia. Some 
are attached to various objects on the ocean floor, while others are 

The cytoplasm is ordinarily not differentiated into the two zones 
and streams out through the apertures, and in perforated forms 
through the numerous pores, of the shell, forming rhizopodia which 
are fine and often very long and which anastomose with one another 
to present a characteristic appearance (Fig. 5). The streaming move- 
ment of the cytoplasm in the pseudopodia are quite striking; the 
granules move toward the end of a pseudopodium and stream back 
along its periphery. The body cytoplasm is often loaded with brown 
granules which are apparently waste matter and in some forms such 
as Peneroplis pertusus these masses are extruded from the body 
from time to time, especially prior to the formation of a new cham- 
ber. Contractile vacuoles are usually not found in the Foraminifera. 

The test of the Foraminifera varies greatly in form and structure. 
It may show various colorations — orange, red, brown, etc. The ma- 
jority measure less than one millimeter, although larger forms may 
frequently reach several millimeters. The test may be siliceous or 
calcareous and in some forms, various foreign materials, such as 
sand-grains, sponge-spicules, etc. which are more or less abundantly 
found where these organisms live, are loosely or compactly cemented 
together by pseudochitinous or gelatinous substances. Certain forms 
show a specific tendency in the selection of foreign materials for the 
test (p. 47). Siliceous tests are comparatively rare, being found 
in some species of Miliolidae inhabiting either the brackish water or 
deep sea. Calcareous tests are sometimes imperforated, but even in 
such cases those of the young are always perforated. By far the ma- 
jority of the Foraminifera possess perforated calcareous tests. The 
thickness of the shell varies considerably, as do also the size and 
number of apertures, among different species. Frequently the per- 
forations are very small in the young and later become large and 
coarse, while in others the reverse may be the case. 

The form of the shell varies greatly. In some there is only one 
chamber composed of a central body and radiating arms which repre- 



sent the material collected around the pseudopodia, as in Rhabdam- 
mina (Fig. 209, a) , or of a tubular body alone, as in Hyperammina (Fig. 
209, d). The polythalamous forms possess shells of various spirals. 
The first chamber is called the proloculum. which may be formed 
either by the union of two swarmers or by asexual reproduction. The 
former is ordinarily small and known as the microspheric proloculum, 
while the latter, which is usually large, is called the megalospheric 
proloculum. To the proloculum are added many chambers which 
may be closely or loosely coiled or not coiled at all. These chambers 
are ordinarily undivided, but in many higher forms they are divided 
into chamberlets. The chambers are delimited by the suture on the 
exterior of the shell. The septa which divide the chambers are per- 
forated by one or more foramina known as stolon canals, through 
which the protoplasm extends throughout the chambers. The last 
chamber has one or more apertures of variable sizes, through which 
the cytoplasm extends to the exterior as pseudopodia. The food of 
Foraminifera consists mostly of diatoms and algae, though pelagic 
forms are known to capture other Protozoa and micro crustaceans. 

All species of Foraminifera manifest a more or less distinct tend- 
ency toward a dimorphism: the megalospheric form has a large pro- 
loculum, is uninucleate and is relatively small in size ; while the micro- 
spheric form possesses a small proloculum, is multinucleate, and is 
large. In addition, there is a difference in the direction of rotation of 
spiral chambers of tests in some species (Myers). For example, in 
Discorbis opercularis, the microspheric form has clockwise rotation 
of the chambers, and the megalospheric form shows counterclock- 
wise rotation. The megalospheric forms are said to be much more 
numerous than the microspheric forms, especially in pelagic species. 
It is possible that, as Myers (1938) pointed out, the flagellate gam- 
etes are set free in open water and have a minimum of opportunity 
for syngamy. 

Lister (1895) observed the development of the megalospheric 
form in Elphidium by asexual reproduction from the microspheric 
form. He noticed flagellated swarmers in megalospheric tests and 
considered them as gametes which through syngamy gave rise to 
microspheric individuals. Recent studies by Myers (1935-1940) 
confirm the correctness of this view, except that in some species the 
gametes are amoeboid. In Spirillina vivipara (Fig. 208, A, 1-5) the 
mature microspheric form (1) which measures 125-1 52ju in diameter, 
becomes surrounded by an envelope composed of substrate debris 
and viscous substance. Within the "multiple fission cyst," nuclear 
and cytoplasmic fissions form numerous small uninucleate megalo- 



spheric individuals which produce tests and emerge from the cyst 
(Si). They grow into mature megalospheric forms which measure 
60-72/x in diameter. Two to four such individuals become associated 

A B C 


Fig. 208. Developmental cycles of Foraminifera (Myers). A, Spirilhna 
vim-para; B, Discorbis patelliformis; G. Elphidium crispa. 1, microsphere 
forms; 2, megalospheric forms, a-c, enlarged views of young megalo- 
spheric forms; 3, beginning of sexual reproduction; 4, gamete and zygote 
formation, a-c, gametes; 5, young microsphere forms, a-c, enlarged views 
of one in each species. 


and transform into "fertilization cyst." (S). The nucleus in each 
individual divides twice or occasionally three times and thus formed 
multinucleate bodies escape from the tests within the cyst envelope 
where many gametocytes are produced by multiple fissions. Each 
gametocyte which contains 12 chromosomes divides into two amoe- 
boid haploid gametes by meiosis. Gametes developed from different 
parents presumably undergo fusion in pairs and zygotes are pro- 
duced (4)- Each zygote becomes proloculum in which the nucleus 
divides twice and when the coiled tubular chamber of test grows to 
about three-quarters of a whorl, young microspheric individuals 
escape from the cyst and lead' independent existence (5) . Myers re- 
ports the development of Patellina corrugata is similar to that of 
Spirillina, except the amoeboid gametes possess 12 haploid number 
of chromosomes. 

In Discorbis patelliformis (Fig. 208, B, 1-5), the same investigator 
noticed no fertilization cyst during the sexual reproduction, but two 
megalospheric individuals come in contact and flagellate gametes are 
produced in them. The zygotes develop within the space formed by 
the dissolution of septa between chambefs and tests; the zygote 
nucleus divides repeatedly within each zygote and forms about 40 
nuclei before a test is secreted. In Elphidium crispa (Fig. 208, C, 
1-5), there is no direct association of megalospheric individuals dur- 
ing sexual reproduction. The flagellated gametes produced in each, 
are set free in the water and the fusion of the gametes depends en- 
tirely upon the chance meeting. 

In Patellina corrugata and Discorbis vilardeboanus, Calvez (1950) 
finds that the postzygotic divisions of the nucleus are mitotic and 
the trophozoite nucleus is diploid, but meiosis occurs in the tropho- 
zoite just before multiple division. 

More than 300 genera of extinct and living Foraminifera are now 
known. Cushman distinguished 45 families. The present work fol- 
lows Cushman in recognizing and differentiating 44 families, and 
lists one genus as an example for each, but places Gromia and allied 
genera in the order Testacea (p. 472). Taxonomy (Cushman, 1948); 
ecology (Phleger and Walton, 1950; Phleger and Parker, 1951); dis- 
tribution (Post, 1951, Ming, 1952). 

Test entirely or in part arenaceous 

Test single-chambered or rarely an irregular group of similar chambers 
loosely attached 
Test with a central chamber, 2 or more arms; fossil and recent. . . . 
Family 1 Astrorhizidae 



Genus Rhabdammina Sars (Fig. 209, a) 

Test without a central chamber, elongate, open at both ends; fossil 
and recent Family 2 Rhizamminidae 

Genus Rhizammina Brady (Fig. 209, b) 

Test a chamber or rarely series of similar chambers loosely attached, 

with normally a single opening; fossil and recent 

Family 3 Saccamminidae 

Genus Saccammina Sars (Fig. 209, c) 

Test 2-chambered, a proloculum and long undivided tubular second 

Fig. 209. a, Rhabdammina abyssorum, X5 (Ktihn); b, Rhizammina 
algaeformis, fragment of, Xl4 (Cushman); c, Saccammina sphaerica, 
X8 (Rhumbler); d, Hyperammina subnodosa, x4 (Brady); e, Ammo- 
discus incertus, X20 (Kiihn); f, Silicina limitata, Xl3 (Cushman); 
g, Reophax nodulosus, X3 (Brady). 

Test with the second chamber, simple or branching, not coiled; 
mostly recent and also fossil Family 4 Hyperamminidae 

Genus Hyperammina Brady (Fig. 209, d) 

Test with the second chamber usually coiled at least in young 
Test of arenaceous material with much cement, usually yellowish 
or reddish brown; fossil and recent . Family 5 Ammodiscidae 

Genus Ammodiscus Reuss (Fig. 209, e) 

Test of siliceous material, second chamber partially divided; 
fossils only Family 6 Silicinidae 

Genus Silicina Bornemann (Fig. 209, f) 

Test typically many-chambered 

Test with all chambers in a rectilinear series; fossil and recent 

Family 7 Reophacidae 


Genus Reophax Montfort (Fig. 209, g) 

Test planispirally coiled at least in young 

Axis of coil, short; many uncoiled forms; fossil and recent 

Family 8 Lituolidae 

Genus Lituola Lamarck (Fig. 210, a) 

Axis of coil usually long, all close-coiled 

Interior not labyrinthic; fossil only Family 9 Fusulinidae 


Fig. 210. a, Lituola nautiloidea (Cushman); b, section through a 
Fusulina (Carpenter); c. Textularia agglutinans, X90 (Rhumbler); d. 
Verneuilina propinqua, XS (Brady); e, Valvulina triangularis, (d'Or- 
bigny); f, Trochammina inflata, X32 (Brady); g, Placopsilina cenomana 
(Reuss); h, Tetrataxis palaeotrochus, Xl5 (Brady); i, Spiroloculina 
limbata, X20 (Brady); j, Triloculina trigonula, Xl5 (Brady) ; k, Fischer- 
ina helix, X32 (Heron-Allen and Earland); 1, Vertebralina striata, X40 
(Kuhn); m, Alveolinella mello, X35 (Brady). 

Genus Fusulina Fisher (Fig. 210, b) 
Interior labyrinthic; fossil only Family 10 Loftusiidae 

Genus Loftusia Brady 

Test typically biserial at least in young of microspheric form; fossil 
and recent Family 11 Textulariidae 

Genus Textularia Def ranee (Fig. 210, c) 

Test typically triserial at least in young of microspheric form 

Aperture usually without a tooth, test becoming simpler in higher 
forms; fossil and recent Family 12 Verneuilinidae 


Genus Verneuilina d'Orbigny (Fig. 210, d) 

Aperture typically with a tooth, test becoming conical in higher 
forms; fossil and recent Family 13 Valvulinidae 

Genus Valvulina d'Orbigny (Fig. 210, e) 

Test with whole body labyrinthic, large, flattened, or cylindrical; 
recent Family 14 Neusinidae 

Genus Neusina Goes 

Test trochoid at least while young 

Mostly free, typically trochoid throughout; fossil and recent. . 
Family 15 Trochamminidae 

Genus Trochammina Parker and Jones (Fig. 210,/) 

Attached; young trochoid, later stages variously formed; fossil and 
recent Family 16 Placopsilinidae 

Genus Placopsilina d'Orbigny (Fig. 210, g) 

Free; conical, mostly of large size; fossil only 

Family 17 Orbitolinidae 

Genus Tetrataxis Ehrenberg (Fig. 210, h) 

Test coiled in varying planes, wall imperforate, with arenaceous 

portion only on the exterior; fossil and recent 

Family 18 Miliolidae (in part) 

Genus Spiroloculina d'Orbigny (Fig. 210, i) 

Test calcareous, imperforate, porcellaneous 

Test with chambers coiled in varying planes, at least in young; aperture 
large, toothed; fossil and recent. .Family 18 Miliolidae (in part) 

Genus Triloculina d'Orbigny (Fig. 210, j) 

Test trochoid; fossil and recent Family 19 Fischerinidae 

Genus Fischerina Terquem (Fig. 210, k) 

Test planispiral at least in young 

Axis very short, chambers usually simple; fossil and recent 

Family 20 Ophthalmidiidae 

Genus Vertebralina d'Orbigny (Fig. 210, I) 

Axis short, test typically compressed and often discoid, chambers 

mostly with many chamberlets; fossil and recent 

Family 21 Peneroplidae 

Genus Peneroplis Montfort (Figs. 4; 211) 

Axis typically elongate, chamberlets developed; mainly fossil 

Family 22 Alveolinellidae 



•i/w a 


b ^ |V c 

«^6 ft c, toc 

Fig. 211. Diagram illustrating the life-cycle of Peneroplis pertusus 
(Winter), a-f, megalospheric generation; g, gamete formation; h-k, 
isogamy; 1-n, microspheric generation; o, multiple division. 

Genus Alveolinella Douville (Fig. 210, w) 

Test globular, aperture small, not toothed; recent only 

Family 23 Keramosphaeridae 

Genus Keramosphaera Brady 

Test calcareous, perforate 

Test vitreous with a glassy lustre, aperture typically radiate, not 



Test planispirally coiled or becoming straight, or single-chambered; 
fossil and recent Family 24 Lagenidae 

Genus Lagena Walker and Jacob (Fig. 212, a) 

Test biserial or elongate spiral; fossil and recent 

Family 25 Polymorphinidae 

Genus Polymorphina d'Orbigny 

Test not vitreous; aperture not radiating 

Test planispiral, occasionally trochoid, then usually with processes 
along the suture lines, septa single, no canal system; fossil and 
recent Family 26 Nonionidae 

Fig. 212. a, Lagena striata, X50 (Rhumbler); b, Elphidium strigilata, 
X40 (Kiihn); c, Operculina ammonoides, X50 (Kuhn); d, Pavonina 
flabelliformis, X30 (Brady); e, Hantkenina alabamensis, X40 (Cushman); 
f, Bolivina -punctata, X100 (Kuhn); g, Rotalia beccarii, X40 (Kiihn); h, 
Asterigerina carinata, X30 (d'Orbigny from Kiihn). 

Genus Elphidium Montfort (Figs. 5; 208, C; 212, b) 

(Polystomella Lamarck) 

Test planispiral, at least in young, generally lenticular, septa double, 

canal system in higher forms; fossil and recent 

Family 27 Camerinidae 

Genus Operculina d'Orbigny (Fig. 212, c) 

Test generally biserial in at least microspheric form, aperture usually 

large, without teeth; fossil and recent 

Family 28 Heterohelicidae 


Genus Pavonina d'Orbigny (Fig. 212, d) 

Test planispiral, bi- or tri-serial with elongate spines and lobed 
aperture; fossil and recent Family 29 Hantkeninidae 

Genus Hantkenina Cushman (Fig. 212, e) 

Test typically with an internal tube, elongate 

Aperture generally loop-shaped or cribrate; fossil and recent. . . 
. Family 30 Buliminidae 

Genus Bolivina d'Orbigny (Fig. 212, /) 

Aperture narrow, curved, with an overhanging portion; mostly 
fossil, also recent Family 31 Ellipsoidinidae 

Genus Ellipsoidina Seguenza 

Test trochoid, at least in young of microspheric form, usually coarsely 
perforate; when lenticular, with equatorial and lateral chambers 
Test trochoid throughout, simple; aperture ventral 

No alternating supplementary chambers on ventral side; fossil 
and recent Family 32 Rotaliidae 

Genus Rotalia Lamarck (Fig. 212, g) 

Genus Spirillina Ehrenberg (Fig. 208, A) 

Genus Patellina Williamson. 

Genus Discorbis Lamarck (Fig. 208, B) 

Alternating supplementary chambers on ventral side; fossil and 
recent Family 33 Amphisteginidae 

Genus Asterigerina d'Orbigny (Fig. 212, h) 

Test trochoid and aperture ventral in young 

With supplementary material and large spines, independent of 
chambers; fossil and recent Family 34 Calcarinidae 

Genus Calcarina d'Orbigny (Fig. 213, a) 

With later chambers in annular series or globose with multiple 
apertures, but not covering earlier ones; fossil and recent. . . . 
Family 35 Halkyardiidae 

Genus Halkyardia Heron-Allen and Earland (Fig. 213, b) 

With later chambers somewhat biserial; aperture elongate in 
the axis of coil; fossil and recent. .Family 36 Cassidulinidae 



Genus Cassidulina d'Orbigny (Fig. 213, c) 

With later chambers becoming involute, very few making up the 
exterior in adult; aperture typically elongate, semicircular; in 

a few species circular; fossil and recent 

Family 37 Chilostomellidae 

Genus Allomorphina Reuss (Fig. 213, d) 

With chambers mostly finely spinose and wall cancellated, adapted, 
for pelagic life, globular forms with the last chamber com- 
pletely involute; aperture umbilicate or along the suture; fossil 
and recent Family 38 Globigerinidae 

Fig. 213. a, Calcarina defrancei, X25 (Brady); b, Halkyardia radiata, 
Xl5 (Cushman); c, Cassidulina laevigata, X25 (Brady); d, Allomorphina 
trigona, X40 (Brady); e, Globigerina bxdloides, X30 (Kuhn); f, Anomalina 
punctulata (d'Orbigny); g, Rupertia stabilis, X50 (Brady). 

Genus Globigerina d'Orbigny (Fig. 213, e) 

Early chambers globigerine, later ones spreading and compressed; 
fossil and recent Family 39 Globorotaliidae 

Genus Globorotalia Cushman 

Test trochoid at least in young, aperture peripheral or becoming 
Mostly attached, dorsal side usually flattened; fossil and recent 
Family 40 Anomalinidae 

Genus Anomalina d'Orbigny (Fig. 213, /) 

Later chambers in annular series; fossil and recent 

Family 41 Planorbulinidae 


Genus Planorbulina d'Orbigny 

Test trochoid in very young, later growing upward 

Later chambers in loose spiral; fossil and recent 

Family 42 Rupertiidae 

Genus Rupertia Wallich (Fig. 213, g) 

Later chambers in masses or branching, highly colored; mostly 
recent, also fossil Family 43 Homotremidae 

Genus Homotrema Hickson 

Test trochoid in the very young of microspheric form, chambers 
becoming annular later, with definite equatorial and lateral 

chambers, often with pillars; fossil only 

Family 44 Orbitoididae 

Genus Orbitoides d'Orbigny 


Brady, B. H.: (1884) Report on the Foraminifera dredged by 

H.M.S. Challenger, during the years 1873-1876. Rep. Voy. 

Chall., 9. 
Calvez, J. le: (1950) Recherches sur les foraminiferes. II. Arch. 

zool. exper. g£n., 87:211. 
Cushman, J. A.: (1948) Foraminifera: their classification and eco- 
nomic use. 4 ed. Cambridge, Mass. 
Illing, Margaret A.: (1952) Distribution of certain Foraminifera 

within the littoral zone on the Bahama Banks. Ann. Mag. Nat. 

Hist., 5:275. 
Myers, E. H.: (1935) The life history of Patellina corrugata, etc. 

Bull. Scripps Inst. Oceanogr., Univ. California Tech. Ser., 3: 

(1936) The life-cycle of Spirillina vivipara Ehrenberg, with 

notes on morphogenesis, etc. J. Roy. Micr. Soc, 56:126. 
(1938) The present state of our knowledge concerning the life 

cycle of the Foraminifera. Proc. Nat. Acad. Sc, 24:10. 

(1940) Observations on the origin and fate of flagellated 

gametes in multiple tests of Discorbis. J. Mar. Biol. Ass. 
Unit. Kingd., 24:201. 

Phleger, F. B.: (1951) Ecology of Foraminifera, northwest Gulf of 
Mexico. I. Mem. Geol. Soc. America, 46:1. 

and Parker, F. L.: (1951) II. Ibid., 46:89. 

and Walton, W. R.: (1950) Ecology of marsh and bay Fo- 
raminifera, Barnstable, Mass. Am. J. Sc, 248:274. 

Post, Rita J.: (1951) Foraminifera of the south Texas coast. Publ. 
Inst. Mar. Sc, 2:165. 

Rhumbler, L.: (1904) Systematische Zusammenstellung derrezen- 
ten Reticulosa (Nuda u. Foraminifera). I. Arch. Protist., 3: 181. 

Chapter 22 
Subclass 2 Actinopoda Calkins 

THE Actinopoda are divided into two orders as follows: 
Without central capsule Order 1 Heliozoa 

With central capsule Order 2 Radiolaria (p. 516) 

Order 1 Heliozoa Haeckel 

The Heliozoa are, as a rule, spherical in form with many radi- 
ating axopodia. The cytoplasm is differentiated, distinctly in Ac- 
tinosphaerium, or indistinctly in other species, into the coarsely 
vacuolated ectoplasm and the less transparent and vacuolated 
endoplasm. The food of Heliozoa consists of living Protozoa or 
Protophyta; thus their mode of obtaining nourishment is holozoic. 
A large organism may sometimes be captured by a group of Heliozoa 
which gather around the prey. When an active ciliate or a small roti- 
fer comes in contact with an axopodium, it seems to become suddenly 
paralyzed and, therefore, it has been suggested that the pseudopodia 
contain some poisonous substances. The axial filaments of the axo- 
podia disappear and the pseudopodia become enlarged and surround 
the food completely. Then the food matter is carried into the main 
part of the body and is digested. The ectoplasm contains several 
contractile vacuoles and numerous refractile granules which are 
scattered throughout. The endoplasm is denser and usually devoid 
of granules. In the axopodium, the cytoplasm undergoes streaming 
movements. The hyaline and homogeneous axial filament runs 
straight through both the ectoplasm and the endoplasm, and ter- 
minates in a point just outside the nuclear membrane. When the 
pseudopodium is withdrawn, its axial filament disappears com- 
pletely, though the latter sometimes disappears without the with- 
drawal of the pseudopodium itself. In Acanthocystis the nucleus is 
eccentric (Fig. 216, b), but there is a central granule, or centroplast, 
in the center of the body from which radiate the axial filaments of 
the axopodia. In multinucleate Actinosphaerium, the axilia filaments 
terminate at the periphery of the endoplasm. In Camptonema, an 
axial filament arises from each of the nuclei (Fig. 214, d). 

The skeletal structure of the Heliozoa varies among different 
species. The body may be naked, covered by a gelatinous mantle, or 
provided with a lattice-test with or without spicules. The spicules 
are variable in form and location and may be used for specific dif- 
ferentiation. In some forms there occur colored bodies bearing 
chromatophores, which are considered as holophytic Mastigophora 



(p. 29) living in the heliozoans as symbionts. 

The Heliozoa multiply by binary fission or budding. Incomplete 
division may result in the formation of colonies, as in Rhaphidi- 
ophrys. In Actinosphaerium, nuclear phenomena have been studied 
by several investigators (p. 204). In Acanthocystis and Oxnerella 
(Fig. 59), the central granule behaves somewhat like the centriole 
in a metazoan mitosis. Budding has been known in numerous species. 
In Acanthocystis the nucleus undergoes amitosis several times, thus 
forming several nuclei, one of which remains in place while the other 
migrates toward the body surface. Each peripheral nucleus becomes 
surrounded by a protruding cytoplasmic body which becomes cov- 
ered by spicules and which is set free in the water as a bud. These 
small individuals are supposed to grow into larger forms, the central 
granules being produced from the nucleus during the growth. For- 
mation of swarmers is known in a few genera and sexual reproduc- 
tion occurs in some forms. The Heliozoa live chiefly in fresh water, 
although some inhabit the sea. Taxonomy and morphology (Penard, 
1905, 1905a; Cash and Wailes, 1921; Roskin, 1929, Valkanov, 1940). 

Without gelatinuous envelope 
Without flagella 

Pseudopodia arise from thick basal parts, branching 

Family 1 Actinocomidae 

Pseudopodia not branching, cytoplasm highly vacuolated 

Family 2 Actinophryidae (p. 507) 

With 1-2 flagella Family 3 Ciliophryidae (p. 508) 

With gelatinous envelope; with or without skeleton 
Without flagella 

Without chitinous capsule 

Without definite skeleton Family 4 Lithocollidae (p. 508) 

With chitinous or siliceous spicules or scales 

With chitinous spicules. . . .Family 5 Heterophryidae (p. 510) 
With siliceous skeleton 

Cup-like plates over body; 2-3 pseudopodia often grouped 

Family 6 Clathrellidae (p. 511) 

Scales flattened, not cup-like 

Family 7 Acanthocystidae (p. 511) 

With chitinous retiform capsule Family 8 Clathulinidae (p. 513) 

With numerous flagella, among axo podia; siliceous scales 

Family 9 Myriophryidae (p. 514) 

Family 1 Actinocomidae Poche 

Genus Actinocoma Penard. Body spherical; one or more contrac- 
tile vacuoles; nucleus with a thick membrane, central; filopodia, not 
axo podia, simple or in brush-like groups; fresh water. 

A. ramosa P. (Fig. 214, a). Average diameter 14-26ju. 


Family 2 Actinophyridae Claus 

Genus Actinophrys Ehrenberg. Spheroidal; cytoplasm highly vac- 
uolated, especially ectoplasm; with often symbiotic zoochlorellae; 
nucleus central; 1 to many contractile vacuoles; axopodia straight, 

Fig. 214. a, Actinocoma ramosa, X630 (Penard); b, Actinophrys sol, 
X400 (Kudo); c, Actinosphaerium eichhorni, X45 (Kudo); d, Camp- 
tonema nutans, X350 (Schaudinn). 

numerous, axial filaments terminate at surface of the nucleus; "sun 
animalcules"; fresh water. 

A. sol E. (Figs. 90; 214, b). Spherical; ectoplasm vacuolated; endo- 
plasm granulated with numerous small vacuoles; a large central 
nucleus; solitary but may be colonial when young; diameter variable, 
average being 40-50^; among plants in still fresh water. Reproduc- 
tion, morphology and physiology (Belaf, 1923, 1924); food habit 
(Looper, 1928). 


A. vesiculata Penard. Ectoplasm with saccate secondary vesicles, 
extending out of body surface between axo podia; nucleus central, 
with many endosomes; 25-30/x in average diameter; fresh water. 

Genus Actinosphaerium Stein. Spherical; ectoplasm consists al- 
most entirely of large vacuoles in one or several layers; endoplasm 
with numerous small vacuoles; numerous nuclei; axopodia end in 
the inner zone of ectoplasm (Fig. 6). 2 species. 

A. eichhorni Ehrenberg (Figs. 6; 214, c). Numerous nuclei scattered 
in the periphery of endoplasm; 2 or more contractile vacuoles, large; 
axial filaments arise from a narrow zone of dense cytoplasm at the 
border line between endoplasm and ectoplasm; body large, diameter 
200-300/x, sometimes up to 1 mm.; nuclei 12-20^ in diameter; among 
vegetation in freshwater bodies. Nuclear change (Speeth, 1919); 
morphology (Rumjantzew and Wermel, 1925); transplantation 
(Okada, 1930). 

A. arachnoideum Penard. Ectoplasm irregularly vacuolated; no 
distinct endoplasmic differentiation; nuclei smaller in number; pseu- 
dopodia of 2 kinds; one straight, very long and the other filiform, 
and anastomosing; 70-80m in diameter; fresh water. 

Genus Camptonema Schaudinn. Spheroidal; axial filaments of 
axopodia end in nuclei about 50 in number; vacuoles numerous and 
small in size; salt water. 

C. nutans S. (Fig. 214, d). About 150^ in diameter. 

Genus Oxnerella Dobell. Spherical; cytoplasm indistinctly dif- 
ferentiated ; eccentric nucleus with a large endosome ; axial filaments 
take their origin in the central granule; no contractile vacuole; 
nuclear division typical mitosis (Fig. 59). 

0. maritima D. (Fig. 59). Small, 10-22/1 in diameter; solitary, 
floating or creeping; salt water. 

Family 3 Ciliophryidae Poche 

Genus Ciliophrys Cienkowski. Spherical with extremely fine 
radiating filopodia, giving the appearance of a typical heliozoan, 
with a single flagellum which is difficult to distinguish from the nu- 
merous filopodia, but which becomes conspicuous when the pseudo- 
podia are withdrawn; fresh or salt water. 

C. infusionum C. (Fig. 215, a). 25-30^ long; freshwater infusion. 

C. marina Caullery. About 10^ in diameter; salt water. 

Family 4 Lithocollidae Poche 

Genus Lithocolla Schulze. Spherical body; outer envelope with 
usually one layer of sand-grains, diatoms, etc. ; nucleus eccentric. 



L. globosa S. (Fig