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A TREATISE ON ZOOLOGY
A TREATISE ON ZOOLOGY
Demy 8vo, Cloth, price 15s. net each; or in Paper
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VOLUMES READY
Part I. (First Fascicle) INTRODUCTION AND
PROTOZOA. By Sir RAY LANKESTER, K.C.B., F.R.S. ;
Prof. S. J. HICKSON, M.A., F.R.S. ; F. W. GAMBLE,
D.Sc., F.R.S. ; A. WILLEY, M. A., D.Sc., T.R.S. ; J. J.
LISTER, F.R.S. ; H. M. WOODCOCK, D.Sc. ; and the late
Prof. WELDOK.
Part I. (Second Fascicle) INTRODUCTION AND
PROTOZOA. By J. B. FARMER, D.Sc., M.A., F.R.S. ;
J. J. LISTER, F.R.S. ; E. A. MINCHIN, M.A. ; and S. Jv
HICKSON, F.R.S.
Part II. THE PORIFERA AND COELENTERA.
By Sir RAY LANKESTER, K.C.B., F.R.S. ; E. A. MINCHIX,
M.A. ; G. HERBERT FOWLER, B.A., Ph.D. ; and GILBERT
C. BOURNE, M.A.
Part III. THE ECHINODERMA. By F. A. BATHER,
M.A., assisted by J. W. GREGORY, D.Sc., and E. S.
GOODRICH, M.A.
Part IV. THE PLATYHELMIA, THE MESOZOA,
and THE NEMERTINI. By Prof. BENHAM, D.Sc.
Part V. MOLLUSCA. By Dr. PAUL PILSENEEH.
Part VII. CRUSTACEA. By W. T. CALMAX.
Part IX. VERTEBRATA CRANIATA. By E. s.
GOODRICH, F.R.S.
7
TREATISE ON ZOOLOGY
EDITED BY
SIR- RAY LANKESTER
K.C.B., M.A., LL.D., F.R.S.
HONORARY FELLOW OF EXETER COLLEGE, OXFORD; CORRESPONDENT OF THE INSTITUTE
OF FRANCE; LATE DIRECTOR OF THE NATURAL HISTORY DEPARTMENTS
OF THE BRITISH MUSEUM
PART I
INTRODUCTION AND PEOTOZOA
FIRST FASCICLE
BY
S. J. HICKSON, F.R.S.
PROFESSOR OF ZOOLOGY, VICTORIA UNIVERSITY OF MANCHESTER
J. J. LISTER, F.R.S.
FELLOW OF ST. JOHN'S COLLEGE, CAMBRIDGF,
F. W. GAMBLE, D.Sc., F.R.S.
ASSISTANT DIRECTOR OF THE ZOOLOGICAL LABORATORIES. \M.
LECTURER IN ZOOLOGY, UNIVERSITY OF MANCHESTER
A. WILLEY, M.A., D.Sc., F.R.S.
DIRECTOR OF COLOMBO MUSEUM, CEYLON
H. M. WOODCOCK, D.Sc.
ASSISTANT TO THE PROFESSOR OF PROTOZOOLOGY IN THE UNIVERSITY OF LONDON
THE LATE W. F. R. WELDON, F.R.S.
LINACRE PROFESSOR OF COMPARATIVE ANATOMY, OXFORD
AND
E. RAY LANKESTER, K.C.B., F.R.S.
•
LONDON
ADAM AND CHARLES BLACK
1909
//
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'
PKEFACE
THE two fascicles of the first part of this treatise give a more
complete account of the Protozoa than is to be found in any
similar work hitherto published. Especial attention has been
given to the treatment of those groups — the Sporozoar
Flagellata, and Hsemoflagellata — which have recently acquired
so much importance in consequence of the discovery that some
of their constituent members are the causes of important
diseases in man and animals.
E. RAY LANKESTEB.
December 1908.
CONTENTS
PAOE
INTRODUCTION . ix
CHAPTER I.— PROTOZOA
SECTION A. — THE PROTEOMYXA 1
„ B. — THE HELIOZOA . .... 14
,, C. — THE MYCETOZOA . . . . . 37
„ D. — THE LOBOSA ...... 68
„ E. — THE RADIOLARIA 94
„ F. — THE MASTIGOPHORA . ... 154
n G. — THE HAEMOFLAGELLATES AND ALLIED
FORMS . . . . . . .193
APPENDJX A. — CHLAMYDOMYXA AND LABYRINTHULA . 274
„ B. — THE XENOPHYOPHORIDAE . . . 284
INDEX 287
vii b '
A TREATISE ON ZOOLOGY.
INTRODUCTION.1
THERE are certain matters which require brief treatment by way
of introduction to the present treatise on Zoology.
The first concerns the limitation of the subject-matter indicated
by the term " Zoology," requiring a statement of what living things
are here considered as animals and what are excluded from that
title. The second concerns the grouping of animals in large series
corresponding to the indications afforded by their structure as to
their genetic affinities. The method adopted in the present work
has been to take large divisions of the Animal series such as are
often called " sub-kingdoms " or " phyla " (or in some instances less
comprehensive divisions) one by one for systematic description and
for more detailed enumeration and justification of the classes, orders,
and families recognised than is usual in handbooks of Zoology.
These large divisions have been assigned for treatment to separate
authors, and in each case the author has given a description of the
characters which justify the recognition of the group which he
treats as an independent series ; to this he has added a more
extended discussion of the range of variety in the structure of the
forms held to be reasonably considered as members of the series.
A special chapter written by me forms the introduction to
volume ii. of this work. It may be regarded as a continuation of
the present chapter, and treats of the division of the higher grade
of animals, which is called the Metazoa (the lower being the
Protozoa), into two branches, the " Parazoa " and the " Enterozoa."
It is, however, chiefly occupied with a discussion of the division
of the Enterozoa into two grades of higher and lower structural
complexity, which are designated respectively the " Enterocoela "
and " Coelomocoela." The chief phyla or large branches of the
animal pedigree are there enumerated, whilst each is subsequently
treated by independent authors.
In the present introductory chapter I have therefore to consider,
besides the question as to what distinctions separate animals from
1 By Sir Ray Laukester, K.C.B.
ix
INTRODUCTION
other living things, the facts which render it necessary to recognise
two great primary grades of animals — a lower called the Protozoa
and a higher called the Metazoa.
A. THE DIVIDING-LINE BETWEEN PLANTS AND ANIMALS.
Living things — Bionta — are without difficulty, and by the
general agreement of both skilled naturalists and the observant
layman, divided into two greatly differing groups or series, the
animals or Zoa and the plants or Phyta, and into those two great
groups only. The study of the one series is called Zoology, and of
the other Phytology, or more usually Botany. It is easy to lay
down certain general propositions by which nearly all animals are
distinguished from nearly all plants. The distinctions which can
be thus indicated all arise from one great difference in the chemical
activity of the living substance of an animal as compared with that
of a plant. Although the living substance of both animals and
plants, to which Hugo von Mohl gave the name Protoplasm, appears
in both series in the form of nucleated corpuscles called cells,
and although the formal appearances and the range of chemical
activities exhibited both by the general protoplasm and by the
nuclear structures of the cells of animals and plants are practically
identical, yet there is a predominant difference in the habitual
exhibition of their activities which separates animals from plants,
and has determined the difference of form and activity characteristic
of the living things assigned to either of the two groups.
Living protoplasm, whether of animal or plant, undergoes
(when the processes of life are not, as they may be for a short or
for a very extended period, suspended) constant chemical change,
requiring the access of free oxygen to the protoplasm and the
consequent oxydation of some of its material — which becomes
" wasted " or lost and carried away by diffusion from the living
protoplasm. This loss has to be replaced, and the process by which
it is replaced is " nutrition " ; the material taken by a living thing
for the purposes of nutrition is its "food."
The result of nutrition is not limited to the repair of loss in
the living thing, but is for a part or the whole of its existence
in excess of the loss ; so that increase of the bulk of the living
material or "growth" is a result. The elements carbon, hydrogen,
oxygen, and nitrogen, combined to form molecules of the highest
degree of complexity, are the essential constituents of living
material. It is these that are oxydised and wasted and pass from
the living thing during life : it is these which have to be replaced.
Animals are unable to assimilate, that is, to utilise as food, the
simpler chemical compounds of carbon or of nitrogen. They can
only take their nitrogen from food which is in the elaborate form of
INTRODUCTION
combination which is called a proteid ; they can only take their carbon
either from a proteid or from a carbohydrate or a hydrocarbon.
These elaborate compounds only occur in the bodies of other
animals or of plants. Hence animals absolutely depend for their
food on other living things. Plants, on the contrary, are (with
certain exceptions) able to take up as food the compounds of carbon
and of nitrogen which may be called the stable or resting condition
of those elements — namely, the simple oxide of carbon — carbonic
acid gas and the simple compound of nitrogen with hydrogen which
is called ammonia, or the oxide of nitrogen which forms nitrates.
This " food " of plants is diffused throughout the earth's surface in
air and water; hence they need to expose a large absorbing surface
to those media ; hence their branches and leaves spread in tree-
like form to the air or to the water, whilst their roots are spread to
the water contained in the soil. Their food is ever moving and
flowing around them : they have neither to move in search of it
nor to seize it. Hence the majority of plants are fixed and find
safety and protection in stability. Animals, on the other hand, have
to obtain their food from the scattered, solid, separate bodies of
plants or of other animals. They have to move in search of it, they
have to seize it when found, and they have to act chemically on
the solid or viscous body or fragment of their prey so as to dis-
solve it and to enable the dissolved material containing the precious
carbon and nitrogen in a high state of chemical combination to
diffuse into their living substance and there be further assimilated
and built up into the material of protoplasm. For these purposes
animals possess structures enabling them to move more or less
rapidly, and others enabling them to seize or grasp. Further, and
of even more fundamental a character as determining their whole
shape and organisation, they possess (with rare and intelligible
exceptions) an aperture, the month, leading into a relatively extensive
cavity, the gut, into which the solid or viscous mass of food is intro-
duced, and when there is chemically dissolved or " digested."
The obvious and predominant difference in the make and habit
of plants as compared with animals is thus connected with the very
great and definite difference in the nature of the food of the two
groups.
These statements are true in a general way, but require
qualification. In the first place, we find it necessary to regard as
genetically part of the great Plant series many organisms which are
not able to procure their carbon from carbonic acid nor their nitro-
gen from ammonia. Only the green plants are able to perform this
constructive feat. The protoplasm of the more superficial cells of
green plants contains corpuscles impregnated with a transparent
green matter known as chlorophyll. In the presence of and in
virtue of the physical action of sunlight screened by their chloro-
INTRODUCTION
phyll, the protoplasm of these cells has the property of decompos-
ing carbonic acid, liberating free oxygen, and combining the carbon
with hydrogen and oxygen to form starch. This is the critical step
in the interaction of chemical elements on the earth's surface, by
which life is at present determined. Were there no assimilation of
carbon from carbonic acid to form starch — by the green plants —
the whole fabric of the living world would tumble to the ground — in
truth, become mineralised. All living matter breaks down, within a
short space of hours or days, to the resting or mineral condition of
carbonic acid and ammonia (or nitrates). Were the building-up
process, the raising to higher potentiality, not incessantly performed
by green plants — a power which chlorophyll and chlorophyll alone
confers on them — all carbon must pass from the reach of the organic
world and living matter come to an abrupt end.
And this is equally true of nitrogen. The nitrogen present in
living protoplasm tends inevitably to the stable inert condition — as
a nitrate, as ammonia, or as the pure dissociated atmospheric gas.
It is only by a subtle chemical process which occurs in the green
plant — as a result of and in connection with the fixation of carbon
as starch — that nitrogen taken up in water by the roots of the plant
as nitrate and as ammonia is brought into combination as part of an
" organic " compound or molecule. Thus in the ultimate history of
the chemistry of living things the animal depends for its necessary
food — proteids, carbohydrates, and hydrocarbons — on chlorophyll,
the " leaf-green " of green plants. Vegetarian animals swallow
and digest these substances built up by plants ; carnivorous animals
swallow and digest animals which have already profited by the
work of the green plant. No animal can take up even a fraction
of a grain of carbon or nitrogen from a stomachful of carbonates,
nitrates, and ammonia.
There are, however, as exceptions plants which are devoid of
chlorophyll and depend upon the results of the constructive activity
of other plants and of animals, just as per contra there are ex-
ceptional parasitic animals which have no mouths or gut and live
in the diffusible nutritive juices elaborated by other animals, which
they absorb by the surface of their bodies. The chemical life of
those plants which are devoid of chlorophyll — the fungi, the
bacteria, and a few others — may be considered as corresponding in
character to that of those tissues or cell-groups of green plants
which lie within the green plant and are devoid themselves of
chlorophyll. Both these tissues and the autonomous fungi and the
saprophytes depend for their food on the products supplied to
them by the chlorophyll-holding cells of green plants. There are
minute filamentous and rod-like plants devoid of chlorophyll
(Bacteria and others) which can take their carbon as tartaric acid
and their nitrogen as ammonia. It is probable that all such non-
INTRODUCTION
chlorophylligerous plants must be regarded as derived from chloro-
phyll-bearing ancestors — by adaptation to a food already somewhat
raised by other organisms above the lowest stage of carbon-
combination.
Again, there are amongst the most highly developed flowering
plants examples here and there of the exceptional and special
development of stomach-like organs with mouth-like openings into
which insects are attracted, and when once entrapped are held
either by the actual movement of a grasping organ or by other
mechanical apparatus, and are digested by chemical secretions
identical in character with those of the animal stomach, the digested
product being absorbed and serving to nourish the plant. Such
cases, whilst they demonstrate in a most striking way the essential
identity of the faculties of the living protoplasm of plant and
animal, do not invalidate the fundamental proposition, that plants
are a series of organisms which have developed their distinctive
form and structure as feeders on the diffused carbonic acid, ammonia,
and nitrates of the circumambient medium ; whilst animals are a
series which have developed their distinctive form and structure
as feeders on scattered — often elusive — live or dead bodies or solid
particles of other animals or of plants, that form being essentially a
locomotive sac with a mouth. Amongst the larger animals, those
visible to the naked eye, there are few exceptions to this rule.
Such exceptions are found in the obviously exceptional and therefore
aberrant internal parasites which require no mouth nor digestive sac.
But there are a few, very rare cases of small aquatic animals
which are provided with chlorophyll-corpuscles and obtain a part
(in one case, the worm Convoluta, the whole) of their nutriment
in the same Avay as does the green plant, namely, in virtue of the
assimilation of carbon from carbonic acid in the chlorophyll-
bearing tissue when under the influence of sunlight. The
chlorophyll-bearing cells of the worm Convoluta and of many
Anthozoa have been shown to be unicellular parasites which have
established the closest relationship to their hosts. But it is by no
means demonstrated that the chlorophyll-corpuscles of Spongilla and
of Hydra are parasitic in origin.1 The fact that they are not
chlorophyll-bearing cells, but simple non-nucleated corpuscles with
a cortex impregnated with chlorophyll precisely comparable to the
chlorophyll corpuscles of green plants, does not permit us to
consider them as parasites which have effected a lodgment and
association with Spongilla and Hydra with any more reason than
we can adduce for so regarding the similar corpuscles in green
plants. The view has been seriously advanced that the latter are,
1 See on this subject my memoir on "The Chlorophyll-corpuscles and Amyloid
Deposits of Spongilla and Hydra" in vol. xxii. (1882) of the Quart. Journal of
Microsc. Science.
INTRODUCTION
in fact, also parasites. This may prove eventually to be susceptible
of something like demonstration, but in the meantime we must
ask where the limit to this assumption that chlorophyll is of
parasitic origin is to be placed.
It cannot be that all chlorophyll — even that observed in all uni-
cellular plants and animals — is to be regarded as " parasitic." And
if we are once able to distinguish certain independent unicellular
organisms which actually manufacture chlorophyll Avithin them-
selves by the activity of their own protoplasm, we shall be able to
study the steps of that process and to judge as to whether the
protoplasm of the green cells of green plants and of the freshwater
sponge and of the green Hydra do or do not form chlorophyll
plastids in the same way and in virtue of the same protoplasmic
capacity as do minute unicellular algae.
There is no reason, a priori, for refusing to ascribe to a tissue-
cell of a Sponge or a Hydra the same capacity to form a chemical
deposit of any kind which a free unicellular organism possesses.
Unfortunately this is not a case in which the simple test of observa-
tion can be applied, so that the question as to whether the tissue-
cell does construct a chlorophyll -corpuscle or does not can be settled
by inspection. The intricacies of structure and growth are in this
matter such as to render direct observation difficult and illusive.
Whilst there are, then, exceptional cases in both plants and
animals as to the great nutritional distinction between the two
series, it is comparatively easy in all excepting the very lowest
forms to satisfy ourselves that the departures from the rule are
specialised derivatives from the main series. The colourless or
greenless plants are descended from green chlorophylligerous
ancestors ; mouthless, gutless animals are descended from mouth-
bearing, gut-hollow animals.
When, however, we come to the very lowest unicellular micro-
scopic forms of life, there is greater difficulty in assigning some of
the minuter organisms to one side or the other, and to some extent
our decision in the matter must depend on the theory we may
provisionally adopt as to the nature of the earliest living material,
which was the common ancestral matrix from which both the
Plant series and the Animal series have developed. The real
question in regard to such a theory is as to whether we find
reason to suppose that the combination of carbon and nitrogen to
build up proteid, and so protoplasm, required, in the earliest state
of the earth's surface, the action of sunlight and the chlorophyll
screen. We must remember that, though these are now necessary
for the purpose of raising carbon, and indirectly nitrogen, from the
mineral resting state to the high elaboration of the organic mole-
cule, yet it is, after all, living protoplasm which effects this marvel
with their assistance ; and it seems (though possibly there are some
INTRODUCTION
who would deny this) that it is protoplasm which has, so to speak,
invented or produced chlorophyll. Accordingly, I incline to the
view that chlorophyll as we now know it is a definitely later evolu-
tion— an apparatus to which protoplasm attained, and as a conse-
quence of that attainment we have the arborescent, filamentous,
foliaceous, fixed series of living things called plants. But before
protoplasm possessed chlorophyll it had a history. It had in the
course of that history to develop the nucleus with its complex
mechanism of chromosomes, and it had during that period to
feed.
The suggestion has been made long ago (see article " Protozoa,"
Ency. Brit, 6th edition), and appears to me not improbable,
that by whatever steps of change that high complex of organic
molecules which we call protoplasm — the physical basis of life — came
into existence, it very probably fed in the first few aeons of its
existence on the masses of proteid-like material which, it may be
supposed, were formed in no small quantity as antecedents to the
final evolution of living matter. If this were the case, the mode of
nutrition of the first living things must have been similar to that
of animals and unlike that of plants. At a later stage chlorophyll
was evolved, the decomposition of carbonic acid became possible,
and the Plant series was started.
In accordance with this conception, we must look for the
representatives of the most primitive forms of life amongst the
minute Protozoa, possessing the simplest methods of nourishing
themselves by the digestion of already elaborated proteid. Such
are the Mycetozoa, which digest dead organic material by contact,
creeping in the form of naked plasmodia of many inches in area
over organic debris ; such, too, are the minute single cells of naked
protoplasm taking in particles of proteid food by extemporised
mouths and digesting them in the cell-body, whilst prehensile and
motor organs are furnished by the extension of the cell-protoplasm
in the form of lobose processes, radiating filaments, or single or
double vibratile flagella. The earliest plants, the Protophyta,
were, it seems most probable, derived from flagellate colony-
building Protozoa (similar to the Volvocinese), which had, at first
without discarding their animal-mode of nutrition (Zootrophic),
acquired the faculty of manufacturing chlorophyll and supplementing
their ingested nutriment by the decomposition of carbonic acid and
the fixation of nitrogen (Mixotrophic). The step from this to a
purely chlorophyll-given nutrition (Phytotrophic) was not a long
one, and indeed occurs in the life-history of some of the Flagellata
at the present day. With the establishment of pure Phytotrophic
nutrition ensued the formation — by simple cell-division and element-
ary variation of cell-aggregation — of filamentous green plants consist-
ing of chains of cells in single series ; to these followed networks of
INTRODUCTION
such chains, then growth and division of the still-connected cells
in two and finally in three dimensions, producing first sheet-like
and finally more solid structures, the constituent cells of which
became variously differentiated and specialised.
Those extremely minute, thread-like (Leptothrix, Spirillum), or
rod-like (Bacillus) plants devoid of chlorophyll, which often break
up without losing vitality into spherules or into granules of
even ultramicroscopic tenuity, known as the Schizomycetes (or
colloquially Bacteria), cannot be considered as primitive. Like the
Fungi and many of the most highly organised plants, they have
descended from chlorophyll-bearing forms, and have become adapted
to a parasitic or saprophytic mode of nutrition whilst retaining
the general characteristics of growth and form of their ancestors.
The intimate connection of the Schizomycetes with the Oscillatoriae
does not seem to admit of any doubt, and forms closely allied to them
develop chlorophyll as well as peculiar blue and red pigmentary
substances, the function of which is obscure but may be related
to their modified nutritional processes. We are thus led to regard
all the non-filamentous, non-chlorophylligerous microscopic forms
which are not referable to the Schizomycetes or to the simpler
Fungi as "Protozoa." The debatable ground is limited to the
chlorophyll-forming Flagellata, amongst which are some which,
being devoid of mouth and at all periods of their growth incapable
of zootrophic activity, are yet so closely allied in life-history and
structure with truly zootrophic species that it is not possible to
draw a sharp line and assign them definitely either to the Animal
or to the Plant series. Such are the Volvocineans, which zoologists
will probably for some time to come consider it desirable (as we do
in the present treatise) to treat of in the description of the Animal
series, whilst botanists will find it equally desirable to discuss
them in connection with closely allied minute Plants.
In view of these considerations, we consider the following
groups of the simplest organisms as belonging to the Animal
series, and as constituting a lowest " grade " of animal organisa-
tion, to which the term Protozoa is applicable. The groups in
question are given the title of "classes," but it will readily be
understood that it is not intended to imply by that term that
they have any exact equivalence in the amount of divergence
from one another to that which is presented by the " classes " of
any one of the phyla of the Metazoa.
PROTOZOA. — Class 1, Proteomyxa; Class 2, Heliozoa; Class 3,
Mycetozoa ; Class 4, Lobosa ; Class 5, Radiolaria ; Class 6,
Mastigophora ; Class 7, Sporozoa; Class 8, Ciliata; Class 9,
Acinetaria.
INTRODUCTION
B. SEPARATION OF THE GRADE PROTOZOA FROM THE
GRADE METAZOA.
Formerly the name Protozoa was used for a sub-kingdom of the
Animal Kingdom equivalent in value to other sub-kingdoms which
were enumerated as the Coelentera, the Vermes, the Arthropoda, the
Echinoderma, the Mollusca, and the Vertebrata. In its earlier use
the great division " Protozoa " was made to include the Sponges,
which we now assign to a divergent line of descent, the Parazoa,
opposed to the main line, the Enterozoa, in the higher grade of
animals called the Metazoa. The removal of the Sponges from
association with the Protozoa is chiefly due to the initiative of
Ernst Haeckel. By this step it became possible to give something
like a definite characterisation of the Protozoa and to mark them
off from all the higher animals. They are definitely characterised
by the fact expressed in the English name Cell-animals (Plasti-
dozoa), or less correctly unicellular animals, whilst all the higher
animals or Metazoa (inclusive of the Sponges) are Tissue-animals
(Histozoa). The fact indicated in these terms is that in
Protozoa a single cell or a colony of equi-pollent cells is the
organic "individual," whilst in the Metazoa the "individual"
is built up by cells which are differentiated into at least two
layers or tissues, the cells of each tissue being of like value
and origin with its fellow -cells of that tissue, but differing
essentially in structure, function, and origin from the cells of the
other tissue or tissues. These statements will be found on critical
examination to hold good in view of our present knowledge of both
Protozoa and Metazoa. Most of the Protozoa are unicellular, and
in those which form many-celled colonies, such as the Mycetozoa,
some of the Iladiolaria, Mastigophora, Ciliata, and Acinetaria, there
is no tendency for those cells to differentiate into groups of cells of
like structure and function to one another, but differing in structure
and function from another group or groups present in the same
colony. The only approach to an exception to this generalisation
is found in the specialisation of a cell here and there in the colony
as a reproductive cell; but, on the other hand, it is to be noted that any
cell in the • colony is potentially a reproductive cell, and there is no
differentiation of a congeries or tissue of cells for reproductive pur-
poses in the general plan of the colonial structure.1 It appears to
be the fact that we do not know of any forms at present existing
which furnish a transition from Protozoa to the Metazoa. There
1 Though the existence of at least two "tissues" in the Metazoa suffices to dis-
tinguish them from all Protozoa, it may legitimately be contended that the congeries
of cells forming the colony of certain Protozoa (e.g. Volvox) is rather of the nature of
a "tissue" than of a merely loosely adherent association of cells which, as we see
in many Protozoan colonies, can and do separate freely and irregularly from such
association.
INTRODUCTION
have been descriptions of supposed independent organisms sug-
gesting such intermediate character (Trichoplax and others), but
the true nature and history of these structures have not been placed
on a definite basis, and do not really admit of discussion. The
nearest case of a transitional form appears to be the Choano-
flagellate " Proterospongia " of Savile Kent, which has been
observed on several different occasions from different localities.
It combines in one colony " amoebocytes " and " choanocytes," but
it appears that the one form of cell develops into the other. It is
certainly not unreasonable to regard Proterospongia as a step
forward from the Choanoflagellata in the direction of the Parazoa.
There is no instance of equally definite character tending to
connect Protozoa of any class with the Enterozoa.
Until recently it was possible to add to this distinction between
Protozoa and Metazoa the very striking one that all Metazoa
reproduce by means of fertilised egg-cells (as well as by other
processes), such fertilised cells being the result of the union of
specially developed egg-cells and sperm-cells. Conjugation of two
cells similar to one another as a preparation to multiplication by
fission was known and described in several Protozoa, but the special
units, the static female egg-cell and the motile male " spermatozoid,"
were unknown in Protozoa. The apparent exception to this pre-
sented by some of the Volvocinean Flagellata was regarded as a
reason for assigning these organisms to the pedigree or great series
of Plants, thus removing them from association with the other
Flagellata. In the Plant series, though many groups both among
the highest and lowest do not present sexual reproductive elements
under the typical forms of egg-cell and spermatozoid (antherozoid),
yet some of the lowest and simplest, as well as some of the higher,
plants do develop motile conjugating " male " cells, which seem to
render the relegation of Volwx to the vegetable series a reasonable
proceeding. Within the last decade, however, we have not only
become acquainted among undoubted Protozoa with instances
of the development of " microgametes " or small conjugating cells,
Avhich are distinguished by their size from the larger egg-cells
or " macrogametes " with Avhich they fuse in order to form a
fertilised "germ," but we now know undoubted Protozoa which
exhibit the breaking up of a parent male unicellular individual into
a number of motile microgametes. These have the appearance and
characteristics of the spermatozoa of higher animals, are developed
from the parent male cell by the same steps as are spermatozoa
from sperm-mother-cells, and proceed to fertilise the female macro-
gametes in the same manner as occurs in the fertilisation of the
egg-cell in Metazoa.
The Coccidiidae among the Sporozoa and certain of the Haemo-
flagellata are the Protozoa in which this phenomenon has been
INTRODUCTION
carefully observed. It is identical in its essential features with the
sexual reproductive phenomena of the colonial Flagellate, Volvox
fjlobator. Not only so, but the egg -cells and spermatozoa thus
developed and uniting are identical in character with the egg-cells
and antherozoids of a vast series of lower and higher plants, and
with those of the whole series of Metazoa. A very important link
in the genetic relationships of Plants and Animals is thus established.
There is no occasion to suppose that they have independently
developed the typical form of the male and the female reproductive
particles. The plants have inherited this from the Protozoa which
gave rise to the earliest chlorophylligerous, phytotrophic organisms.
It is perhaps necessary to remark that further observation is
necessary in these lowest forms as to the precise steps in the
preparation of the nucleus and its chromatin in each of the
conjugating gametes for the definite union of fertilisation. There
is abundant evidence that it is of the same nature as that which
occurs in the sexual cells of higher organisms, but in special details
we may have to recognise some differences.
C. SEPARATION OF THE CLASSES OF PROTOZOA INTO GRADES OF
LOWER AND HIGHER STRUCTURE.
The question as to whether the various classes of Protozoa are
to be regarded as nine separately divergent lines of descent, starting
from a common primitive ancestry not represented at the present
time by any one of them, or whether some of them possess closer
genetic relationship inter se than do others, is a very difficult one.
It has been proposed at various times to seek for evidence of such
closer affinity in the development of a cortical firmer layer of the
cell-protoplasm (as in most Sporozoa and in the Ciliata), as opposed
to the retention of the uniform viscid character of the protoplasm
(Lankester, Ency. Brit., article "Protozoa"), and again it has been
considered probable that all those forms which produce temporary
lobose or filnmentar extensions of the protoplasm, as locomotor or
grasping organs, may have a genetic community of origin which
separates them from those provided with either isolated flagella or
with " cilia " of vibratile protoplasm. Some or other, however, of
the forms which it is found necessary, on account of the affinities
indicated by their life-histories and other details of structure, to
class as Flagellata (Mastigophora) exhibit combinations of characters
which render both these attempts at grouping unsatisfactory.
We find Flagellata (see the section on this group) which produce
extensive amoeboid processes, and yet possess a flagellum, whilst
the majority have a distinctly corticate protoplasm. Among the
Sporozoa (for which refer to the section on that group in the second
fascicle of Part I. of this treatise), which are with these rare excep-
tions strongly corticate, we find genera which produce lobe-like and
INTRODUCTION
pointed "pseudopodia" from their superficial protoplasm (Zygoco-
metes and others). It seems that in any attempt at a phylogeny of
the Protozoa we should have to treat the assemblage of forms now
classed as Mastigophora (Flagellata) as a central group from which
the other eight classes have been derived, whilst embracing in
itself several specialised lines of descent, including that which has
given rise to the primitive green plants.
The indication of a higher and later elaboration of structure,
as distinct from a lower and more primitive, by means of the
classifieatory artifice of " grades," has, however, been introduced in
the present work by Professor Hickson in regard to the classes of
Protozoa by a consideration of the cell -nucleus. The condition
of this important structure justifies, he considers, the separation of
the classes of Protozoa into a lower and a higher grade — the
Homokaryota and the Heterokaryota — and it is not improbable
that further study of the lower grade will lead to the subdivision
of that assemblage into sub-grades.
The history of the nucleus of the corpuscle of protoplasm, that
corpuscle which it is customary to regard under the name of " the
cell " as the unit of living structure, is at present absolutely un-
known and altogether a matter of conjecture. It may perhaps be
conceded as highly probable that the earliest protoplasm was with-
out nucleus or differentiated nuclear material. It is a legitimate
contention that such a substance should not be called " protoplasm "
at all, since Hugo von Mohl- invented this term to describe the
viscid contents of a vegetable cell expressly including the nucleus
a? part of it. It was proposed some twenty-five years ago by
Ed. van Beneden to call the earlier non-nucleated stage of living
matter "plasson," and it seems to me by adopting this term we
can preserve the word " protoplasm " for its original use. At the
same time it is important to avoid using the word " protoplasm," as
is not unfrequently done, to signify the critical chemical body which
undoubtedly is present in living protoplasm and is the apex of the
pyramid or the top of the fountain, to which a variety of chemical
bodies are leading and from which another series of chemical bodies
are receding at every moment of the chemical activity of living
protoplasm. Protoplasm is not a chemical body but a structure,
and its nuclear particles, as well as its definitely formed nucleus
consisting of chromatin and other constituents, are parts of it. It
seems necessary to have a word by which to refer to the highest
group of chemical molecules to which one set of chemical processes
in the cell are always leading and from which another series are reced-
ing. I proposed some years ago (Ency. Brit., article "Zoology")
to speak of this hypothetical body as " plasmogen." In the same
way it is necessary to avoid the tendency which exists to employ
the word " protoplasm " to describe cell-substance both when con-
INTRODUCTION
sidered as apart from the nucleus and when actually existing in an
unmanipulated simplest living thing without any nucleus or nuclear
matter. We have seen that " plasson " is the name which has been
proposed for the latter ; for the former the word " cytoplasm " is
frequently used, whilst " nucleoplasm " is applied to that part of the
cell-protoplasm which is the nucleus. The use of the word " cyto-
plasm " in this sense is certainly objectionable, as it signifies " the
cell-plasm " and is merely a synonym of " protoplasm." It would
be better to term the extra-nuclear substance of the protoplasmic
corpuscle " periplasm."
As a hypothesis we may assume that living matter was at one
time in the condition of " plasson," though it has yet to be shown
that " plasson " is in existence at all at the present day. The
next hypothetical stage is the development in distinct granular
form of the material which later became aggregated as a nucleus.
We may apply the word "protoplasm" to this stage, with a
qualifying adjective, " konio-karyote " (powder-nucleated). This
condition is known as actually existing in certain phases of the
ciliate Protozoa (Trachelocerca), and possibly is to be recognised
in some degenerate Protophyta and in some of the Proteomyxa
(whether degenerate or archaic) amongst Protozoa. The third stage
in the hypothetical development of protoplasm consists in the
aggregation of the scattered nuclear granules to form one or more
nuclei of definite structure and properties. Usually but one such
nucleus is formed, but to cover the case of the existence of two or
more similarly organised nuclei the term Homokaryote (proposed
by Professor Hickson) may be used for this condition. The nucleus
of the Homokaryote cell is in leading features of its structure
identical with that of the tissue-cells of higher organisms. It
consists of nuclear capsule, nuclear hyaloplasm, and of chromatin
elements. The optical, chemical, and physiological analysis of the
nuclei of Protozoa and Protophyta has not been extended to a
sufficient number of instances, at present, to render it possible to
trace the steps (if they are still traceable) by which the complete
structure of the nucleus and its activity in cell-division were evolved.
It is not yet clear whether there are among Protozoa and Proto-
phyta any surviving simpler phases of the nucleus, or whether
apparently primitive phases which are described are so interpreted
owing to incomplete observation or, on the other hand, owe their
simplicity to a degeneration from a more highly developed condition
of the nucleus. It is, however, certain that there are cases amongst
the Protozoa in which the structure and activity of the nucleus in
cell-division conforms very closely to those of the tissue-cells of
higher animals and plants, if not absolutely identical with them.
There are, however, in certain Protozoa special modifications of
the nuclear structure which have not yet been shown to occur in
INTRODUCTION
Metazoa, nor in plants. The most striking of these is the division
of the nucleus in Ciliata and Acinetaria into two unequal and
dissimilar portions, the mega-nucleus and the micro-nucleus, which
appear to be the portions of the primary nucleus which preside
over the somatic (the larger) and reproductive activities (the
smaller) respectively. Professor Hickson has made use of this
differentiation of the nucleus into two parts in order to establish
a higher grade of the Protozoa — the Heterokaryota as distinguished
from the Homokaryota.
Amongst those forms, however, which are classed by him as
Homokaryota, there are (as he recognises) certain forms amongst
the Flagellata which also exhibit a differentiation and segregation
of the nucleus, but with functions for the separated elements
different from that shown in the Ciliata. This case is that of the
formation of a separate nuclear body, the kineto-nucleus, in con-
nection with, and apparently controlling the activities of, the large
and powerful flagellum of certain flagellate forms (Trypanosoma,
Noctiluca). It seems that the word Heterokaryote would strictly
apply to these forms also, although the "heterosis" is not the
same as that seen in Ciliata. It would be premature to attempt to
introduce a terminology indicating these different specialisations of
nuclear structure in the Protozoa until much further study has
been given to the subject. It is not at all improbable that researches
which are now in progress will in the course of a few years giA^e
us, first of all, a better understanding of the chemical nature and
activities of the substances which are merely brought into view
by colour-staining as form-elements in the nucleus,1 and secondly,
a far more critical knowledge than we at present possess of the
rudimentarily aggregated and diffuse stainable matter which is
interpreted as " nucleus " in some of the Protozoa, in some of the
Cyanophyceae, in Schizomycetes, and in the yeasts and hyphae
of lower fungi.
Whilst therefore recognising the important separation of the
Ciliata and Acinetaria effected by having regard to the nuclear
structure of those groups and that of the other classes of Protozoa,
so far as we at present know them, I am unwilling to emphasise the
arrangement of the Protozoa into grades according to their nuclear
structure in the present state of knowledge. I should not wish to
go farther at present in grouping the classes of Protozoa than to
suggest that they should be considered as diverging lines of descent
radiating from a central group which possessed the combination of
characters presented at the present day by the simpler Flagellata.
1 The researches of Professor Macallum of Montreal iii this direction will, it
may be hoped, be continued and developed.
CHAPTER I.— PROTOZOA
SECTION A. — THE PROTEOMYXA l
IN the study of the Protozoa a number of forms are found
which are difficult to place in any of the larger orders or families.
The difficulty arises in many cases from what is called their
simplicity of structure, and partly from our ignorance of their entire
life-history. The more we learn of the structure of the Protozoa,
the more hazardous does it become to apply the expression " simple "
to any living organism, but what is really meant by the term
" simple " as applied to these organisms is that they exhibit no
definite structure or structures such as skeleton, flagella, or nuclei
that are so constant in their form and character that they can be
seized upon by the systematist and used for purposes of classifica-
tion. When characters of this description appear during one phase
only of the life-history of an organism they may indicate its
affinities if not its true systematic position, but when the life-history
is not completely known there may be no characters which can
possibly serve for placing the organism with others in any
system of classification. In the early history of Protozoology there
was a time when it was considered that some of the very small
and obscure organisms consisted of a cytode of protoplasm in
which there was no structure corresponding with the nucleus of the
higher organisms and cells. Such organisms were placed in a class
Monera by Haeckel in 1868. Subsequent researches proved that
in many of these organisms one or many minute structures occur
which give the same reactions as the chromatin of the nucleus,
and the conclusion was, in some cases too hastily, drawn that all
of them would in time be shown to be nucleated. Modern
researches on the nuclear structures of Protozoa have thrown
much light on this vexed question. They have shown that the
nucleus may discharge into the cytoplasm, or give rise by total
fragmentation to, a number of minute granules of chromatin — the
chromidia — and that these granules do not degenerate, but retaining
their vitality may again aggregate together in the formation of new
nuclei. There may thus occur in the life-history of the higher
Protozoa a stage which is strictly speaking non-nucleate (akaryote).
1 By Prof. S. J. Hickson, F.R.S.
1 i
THE PROTEOMYXA
This does not imply, however, that the organism is at this stage
devoid of nucleoplasm, but that the nucleoplasm is not concentrated
in the form of a definite nucleus or kernel but is scattered or
diffused. This conception may be expressed by saying that the
stage is akaryote but is not moneran. There is no nucleus but
there is nucleoplasm. In Amoeba, Pelomyxa, and others in which
such a stage occurs the nucleus is present during the greater
part of the life-cycle, the akaryote stage being antecedent only to
nuclear multiplication or gametogenesis.
In the Proteomyxa, on the other hand, the akaryote condition is,
as a rule, of much longer duration, and it is possible that in some
cases the diffused nucleoplasm or scattered chromidia do not collect
together in any stage to form a defined nucleus.
It seems probable, then, that the protoplasm of the Proteomyxa
really represents the protoplasm of the higher Protozoa and
Metazoa plus the substance of the nuclei. It is a substance which
van Beneden (9) in 1871 proposed to call "the plasson," that is,
the formative substance "which is capable of becoming, either in
ontogenetic course or in phylogenetic course, monocellular elements
after that the chemical elements of the plasson have been separated
to constitute a nucleus and a protoplasmic body."
Our knowledge of the nucleus or chromidia of the genera that
are here grouped together in the class Proteomyxa is at present
very scanty. Vampyrellidium is said to have a nucleus m all stages
of its life- history. Zopf states that a definite clear nucleus is
present in all species of Fampyrella, but it is often obscured by
chlorophyll and other bodies in the cytoplasm. There seems to be
little doubt, however, that the nucleus is not present in all stages
of the vegetative life of F'ampyrella, as several observers Avho
have carefully re-examined its structure have failed to find any
definite nucleus. Recently, however, Dangeard (13) has shown
that nuclei are present in the cysts, and that they divide by karyo-
kinesis. In Tetramyxa there are said to be minute nuclei, but these
are probably chromidia. In Plasmodiophora true nuclei are un-
doubtedly present at the time of spore-formation, as they have been
observed to divide by karyokinesis. It is probable also that a
defined nucleus is present during the flagellate and amoebula phases
of most of the Proteomyxa (Fig. 8, B, H), but it is clear that for
a time during the plasmodium stage the nuclei are disintegrated.
In Endyonema nuclei appear to be wanting during the active vege-
tative phase in the filaments of its host -plant (Lingbya), but
definite nuclei are constituted when the body contracts in the
formation of the zoocyst.
Many of the genera included in the group have been seen only
once, and we are still in ignorance of their nuclear condition, but
in Gymnophrys, Biomyxa, Gloidium, Leptophrys, and Protamoeba,
THE PROTEOMYXA
which have been studied by other observers than their original
discoverers, no defined nuclei have been found.
A considerable number of genera are parasitic upon freshwater
algae during at least one stage of their life-history, such as Vam-
pyrellidium, F'ampyrella, Leptophrys, Endyonema, Enteromyxa, Col-
podella, Pseudospora, Gymnococcus, Aphelidium, Tetramyxa, and
Ectobiella. Tetramyxa causes the formation of gall-like growths
on Ruppict and other freshwater
plants. Bursulla occurs in horse-
dung. Haplococcus occurs in the
muscles of the pig, but is appar-
ently harmless. The only species
that is of any economical import-
ance is Plasmodiophora brassicae,
Woronin, which attacks turnips FIO. i.
and Causes the disease known as Ectotnella plaUaui. A, a specimen attack-
,/T-T j rr\ » »JTT i • >; ing Licmophora ; ps, the pseudopodium that
"± ingersand IOCS, Or "Hanbunes. is pushed into the substance of the host; v,
A rrmsirW-iblp nnmbpr nf 0-pnpra the vacuole formed by the host containing
A C OI genera granules produced by the digestive action
are not parasitic and feed upon of the pseudopodium. B, tiie biflag«iiate
, , . zoospore of Ectobiella. (Alter de Bruyne.)
minute animal and vegetable
organisms. Such genera are Gymnophrys, Biomyxa, Protomyxa,
Gloidium, and others.
In the vegetative condition the body emits pseudopodia. These
pseudopodia may be roughly arranged in three categories.
In Protamoeba, Gloidium, Enteromyxa, etc., the pseudopodia are
usually lobate like those characteristic of the genus Amoeba.
In F'ampyrella, Colpodella, Monobia, Myxastrum the pseudopodia
are radiate in position, very delicate and rarely anastomosing, like
those of an Actinophrys.
In Biomyxa, Gymnophrys, Penardia they are delicate and anasto-
mosing, like the pseudopodia of the Foraminifera.
In Endyonema, Haplococcus, Aphelidium,, and other endoparasites
the form of the body is adapted to the spaces of the host and true
pseudopodia are not formed.
In Protomyxa, Myxastrum, Protomonas, Bursulla, Plasmodiophora,
a. number of amoebulae unite to form a plasmodium, and it is
possible that plastogamy also occurs in F'ampyrella, Leptophrys, and
some others. In Monobia a number of stellate individuals unite to
form an open network (Fig. 4).
A contractile vacuole does not usually occur in Proteomyxa,
but it appears to be a constant feature in Gloidium and Ciliophrys.
Non-contractile vacuoles occur in many of the genera.
Although very little is known about the life -history of the
Proteomyxa, it seems probable that they all, at some time, form
.cysts or spores. In Plasmodiophora the protoplasm of the plasmodium
breaks up into a large number of simple spores, which are able to
THE PROTEOMYXA
resist desiccation, and are probably simple hypnocysts.1 In other
cases the cysts are larger, and the contents give rise to three or
four (Vampyrella lateritia, Fig. 2) or a large number (Protomyxa,
x, Fig. 6, and Diplophysalis) of spores, which may be
either naked or protected by a membrane. These
cysts are protected by one or more cyst-membranes,
and the outer of these may be irregular or spiny or
gelatinous in texture. Occasionally three or four
small areas on the cyst-wall are provided with a
thinner membranous coat, and the spores escape by
breaking through these areas only (Haplococcus) ; but
Cystic phase of usuaiiy the cyst-wall breaks down and liberates the
Vampyrella. Ihe J J
contents of the spores, or the spore escapes through any part of the
cyst have divided , ' -T t i« ii_ i
into four equal membranes. In spore -formation the protoplasm
three' aref visible! usually discharges all extraneous matters, and one
(After Lankester large or a number of smaller granules of these
and Cienkowski.) .° • » i i?ri i
ejecta are found between the wall of the cyst and
that of the spores. There is no evidence at present that any
process of conjugation occurs between the liberated zoospores,
except in Ciliophrys (Cienkowski), and, in the absence of any
systematic study of the nuclear substance of the spores, we are not
in a position to state that the condition of the nuclei or nucleo-
plasrn of the spores is in any way different to that of the other
phases of life. There is therefore no justification whatever for
the assumption that any form of cyst -formation indicates or is
associated with a sexual process.1
A remarkable phenomenon has recently been described by de
Bruyne in Leptophrys mllosa. After a period of feeding, the animal
becomes spherical in shape
and enters upon a period of
rest. From the surface there
are protruded a number of deli-
cate filaments (Fig. 3) which
terminate in hyaline globules.
These globules are discharged
and the filaments after some
time are slowly withdrawn.
When conditions are
favourable there emerge
from the Cyst One Or more Leptophrys vlllosa. A, a specimen actively feed-
/»T j. ing, showing, v, a large non - contractile vacuole ;
(iUOnadineae aZOO- d, the diatoms on which it is feeding ; and t, a tuft
B.
Fio. 3.
<vr rmo /-»•
< p
of pointed pseudopodia at the posterior end of the
body. B, a resting stage of the same animal, pro-
onnrAQA
sporeae, j
more flagellulae (Monadineae villed with filamentous processes, p, which discharge
r-r e\ mi minute globules, s.p, of hyaline protoplasm. (After
ZOOSpOreae, Zopf). Ihe deBruyne.)
1 According to von Prowazek the nuclei of the spores of Plasmodiophora are
formed by karyogamy (Arb. aus den kaiserl. Gesundheitsamte, xxii., 1905, p. 396).
THE PROTEOMYXA
amoebulae either grow and become Actinophrys-like in form (l~am-
pyrella) or unite to form plasmoclia (Leptopkrys, Endyomma, etc.).
The flagellulae are provided usually with one, but sometimes
two (Dtplophysalis, Gymnococcus) whip-like cilia, and sometimes also
with a vacuole. They sometimes swim about actively and attack
the organisms on which they feed (Cdpoddla, Fig. 8, A); but usually
they soon withdraw their cilia and become amoeboid in shape, and
the amoebulae thus formed either unite to form plasmodia or grow
independently into the adult form.
The classification of Proteomyxa has always presented innumer-
able difficulties, and even at the present day our knowledge is so
incomplete that nothing better than a tentative arrangement of the
genera can be suggested.
A large number of the genera were placed in a division
(Monadineae) of the Mycetozoa (Pilzthiere) by Zopf, others are
regarded as Foraminifera nuda by Ilhumbler, and Biitschli included
several of the genera in the Heliozoa.
Zopf further divided his genera into two groups, the Mona-
dineae azoosporeae and the Monadineae zoosporeae. In the former
the cysts give rise to amoebulae, and in the latter to flagellulae.
It does not appear satisfactory, however, to use the characters
of the swarm-spores alone as a basis of classification. Pseudospwa,
with a flagellate zoospore, is clearly related to Vampyrella and
its allies, which have an amoebulate zoospore ; and Enteromyxa,,
Myxastrum, and other genera, with an amoebulate zoospore, appear
to have no close relation to Vampyrella.
FIG. 4.
Monobia confluens. A number of individuals connected together by protoplasmic strands
to form a loose meshwork colony. (After Schneider.)
In attempting to classify the Proteomyxa, certain genera stand
out as clearly related to other groups of Protozoa. Thus Monobia
is closely related to the Heliozoa, Protogenes to the Foraminifera,
Protamoeba and Gloidium to the Gymnamoebida, and Plasmodiophora
THE PROTEOMYXA
to the Mycetozoa. Taking into consideration the form assumed by
the pseudopodia, the habit of plasmodium- formation, as well as
the character of the zoospores, most of the other genera can be
arranged around these as central types. But there still remain
some forms whose affinities are at present quite obscure, and these
must be separated for the present into a group by themselves.
The genera are here arranged in five groups according to their
supposed affinities with the other orders of Protozoa.
GROUP A.
The following two genera appear to have affinities with the Gymna-
moebida.
Nothing whatever is known concerning their life-history, and it is
probable they will prove to be but a stage in the life-history of an Amoeba.
Protamoeba, Haeckel, is like an Amoeba, but without any definite
nucleus or contractile vacuole. Freshwater and marine. 1 10 /x (Penard).
Gloidium, Sorokin (Fig. 5), differs from Protamoeba in possessing a
contractile vacuole. Occasionally the surface is denticulated. Fresh-
water, 71 fj.. G. inquinatum, Penard, 385 p. The genus Gringa, Frenzel,
is probably a species of Gloidium.
FIG. 5.
Four stages in the division of Gloidium qitadrifidum. c.v, contractile vacuoles. (After
Sorokin.)
GROUP B.
The genus Monobia in this group is closely related to Heliozoa.
Monopodium and Vampyrella are closely related to one another,
and agree with Vampyrellidium and Pseudospora in having a stage
with delicate radiating pseudopodia like an Adinophrys. Leptophrys
has affinities with Vampyrella, but differs from it in the shape of the
body, which is irregular. Myxastrum is in some respects intermediate
between the genera included in this group and those in Group D.
(IV.) l Monobia, Schneider (Fig. 4). A number of Actinophrys-like
individuals, but without nucleus or contractile vacuoles, and of a bluish
1 As the genera included in the Proteomyxa in this volume have been shifted
about from one class to another by different authors, the roman figures in brackets
have been introduced to indicate to the reader the position assigned to each genus by
the leading writers on Protozoology, when it differs from that given to the same genus
iu the text. Thus the genera marked (I.) were referred to the Monadineae azoosporeae,
(II.) to the Monadineae zoosporeae of the Mycetozoa by Zopf ; (III.) to the Foraminifera
nuda by Rhumbler (22) ; (IV.) to the Heliozoa by Biitschli and Schaudinn.
THE PROTEOMYXA
colour by transmitted light, are united into a colony by the fusion of the
ends of their contiguous pseudopodia. Reproduction by fission has been
observed, but no process of spore-formation is known. Freshwater.
(I.), (IV.) Vampyrella, Cienkowski (Fig. 6, 5). Several species of
this widely distributed genus are known. There is an Actinophrys stage
in which, according to some authors, there is a nucleus. Vampyrella
lateritia attacks Spirogyra by pushing a lobate pseudopodium into the
cell and gradually absorbing its contents. V. gomphonematis attacks the
stalked diatom Gomphonema, completely surrounding the frustules and
absorbing their contents. Cysts are formed surrounded by a single
smooth membrane, the animal discharges particles of undigested food
FIG. 6.
1, Protomyxa aurantiaca, Haeckel, plasmodium phase. The naked protoplasm shows branched,
reticulate processes and numerous non-contractile filaments It is in the act of engulfing a
Ceratium. Shells of engulfed Ciliata (Tintinnabula) are embedded deeply in the endoplasm,
a. 2, cystic phase ot Pfotomyaea; <i, transparent cyst-wall; 6, protoplasm broken up into
spores. 3, flagellula phase of Protomyxa. 4, amoebula phase of the same, the form assumed after
a short period by the flajjellulae. 5, Vampyrella lateritia. Cienk. Actinophrys stage penetrating
a cell of Spirogyra, b, by a process of its protoplasm, c, and taking up the substance of the Spiro-
gyra cell, some of which is seen within the Vampyrella, a. 6, large individuals of Vampyrella
.showing pseudopodia, e, and food-particles, a. (From Lankester, after Haeckel and Cienkowski.)
materials and these are found with the shrunken protoplasm within the
cyst- wall. Occasionally a second membrane is formed around the
shrunken protoplasm. The protoplasm divides within the cyst-wall, and
the nuclei of the spores thus formed are 2 p. in diameter and divide
by karyokinesis. From the cyst there escape one, but usually four
or five amoebulae, which soon develop radiate pseudopodia and float
away in search of their food. In some species (e.g. V. gomphonematis) it
THE PROTEOMYXA
seems certain that several individuals may fuse to form a plasmodium.
No contractile vacuoles occur at any stage. The size varies consider-
ably, 20-70 p.. They are nearly all freshwater forms, but one species,
V. gomphonematis, is also marine.
Monadopsis, Klein, is probably a species of Vampyrella.
(I.) Vampyrellidium, Zopf. This genus is parasitic on freshwater
Algae, particularly on Lingbya. Two kinds of cysts are formed, the
zoocysts with a clear homogeneous membrane, and the hypnocysts with a
thicker membrane. In other respects it is closely related to Vampyrella. A
nucleus surrounded by a hyaline area is said (Zopf) to occur at every stage.
(I.) Leptophrys, Hertwig and Lesser (Fig. 3), appears to be closely
related to Vampyrella, but it forms larger vacuolated plasmodia by the
fusion of the amoeboid zoospores. It is also characterised by the presence
in the protoplasm of numerous paramylum granules. Like Vampyrella
it is found parasitic on various freshwater lower Algae. It is either
colourless or tinged with chlorophyll. The cysts are sometimes 0'25 mm.
in diameter. They give rise to three or four amoeboid zoospores. No
nuclei have been observed at any stage.
(IV.) Monopodium (Haeckelina), Mereschkowsky, is an Actinophrys-like
form with hyaline protoplasm and very delicate radiating pseudopodia
attached to foreign bodies by a stalk. 0'2 mm. White Sea. Arclierina
(see p. 33).
(IV.) Nuclearia, Cienkowski (Fig. 8, E), also appears to be related to
Vampyrella, but as a nucleus or nuclei and contractile vacuoles have been
observed by several authors, it is perhaps more natural to regard it as a
member of the order Heliozoa.
(II.) Pseudospora,1 Cienkowski, is a small Proteomyxan, 3-4 //,, which feeds
upon Oedogonium, Spirogyra, etc. It is related to Gymnococcus and other
members of Group C in producing flagellate zoospores. These zoospores,
provided with one or two flagella and a minute nucleus, penetrate the
bells of the host-plant and give rise to an Actinophrys-like stage, but
they do not fuse to form a plasmodium. When they are fully fed the
numerous pseudopodia are withdrawn and an amoeboid form is assumed
previous to encystment (Fig. 8, B, C). Diplophysalis, Zopf, seems to be
closely related to Pseudospora.
(I.), (IV) Myxastrum, Haeckel, was found on the shores of the
Canary Islands and is marine. It has a stage with numerous radiating
pseudopodia, but forms plasmodia which attain to 0'5 mm. in diameter.
The plasmodium encysts as a whole and the protoplasm forms 100 or
more spores which give rise to amoeboid zoospores.
(IV.) GiliophrySj Cienkowski (Fig. 8, G, H), probably belongs to this
group. It is similar to Nuclearia in some respects, but at times it with-
draws its radiating pseudopodia, becomes oval in shape, and swims rapidly
by means of a long flagellum. Freshwater.
GROUP C.
In this group there is a stage when fine branching and anasto-
_ J For Pseiidospora volcods, see Mastigophora, p. 168.
THE PROTEOMYXA
niosing pseudopodia are formed and the affinities seem to be with the
Foraminifera. Arachnula has some affinities with Nudearia and is re-
garded as a Heliozoon by some authors.
(III.) Protogenes, Haeckel (Fig. 7), is a small spherical organism
with very numerous and delicate radiating and anastomosing pseudopodia
Neither vacuoles nor nuclei have
been observed. Marine.
(III.) Biomyxa, Leidy, is a
widespread genus occurring both
in fresh and salt water. It
passes though a spherical stage
with radiating pseudopodia, but
afterwards assumes a variety of
.elongated or outstretched shapes
with a few long, isolated, branch-
ing and anastomosing pseudo-
podia. One large or many small
nuclei are said to occur (Rhum-
bler). In B. vagans there are
numerous minute contractile (?)
vacuoles, but in B. (Gymnophrys)
cometa there are none. It occurs
in swampy sphagnum ground in
this country. No definite nuclei
have been observed and nothing
is known concerning its life-
history. The genera Gymnophrys,
•Cienkowski (Fig. 8, D), and
Penardia, Cash, seem to be allied to Biomyxa. It has been suggested
by Archer that Gymnophrys is but a detached portion of a Gromia,
and West (27) has found it in a collection containing a large number
of specimens of this Foraminifer.
(III.) Arachnula, Cienkowski (Fig. 8, F), also is closely related to
Biomyxa, but it forms long strands terminating in branching extremities
provided with tufts of delicate anastomosing pseudopodia. Cysts have
been described. It is found in fresh and brackish water.
(III.) Pontomyxa, Topsent, is a form closely allied to Biomyxa and
Penardia. The body assumes a variety of ribboned or dendritic forms,
with numerous or interrupted groups of anastomosing pseudopodia.
P. pallida from the Mediterranean Sea is colourless, but P. flava, like
Penardia, is golden yellow in colour. P. flava was found in 35-50
metres oft" the French coast and also in the Mediterranean Sea. The
nuclei are said to be very small and reproduction occurs by multiple
fission.
(III.) Rhizoplasma, Verworn (26). Spherical or sausage-shaped bodies
of an orange-red colour, with numerous anastomosing pseudopodia, 5-10
mm. in diameter when expanded, found in the Red Sea, are placed in
this genus. There are 1-3 large transparent vesicular nuclei. The
.coloured granules circulate in the pseudopodia.
FIG. 7.
Protogenes primordialis, Haeckel, from Schultze's
figure.
10
THE PROTEOMYXA
(III.) Didyomyxa, Monticelli, is like the preceding genus, but with
colourless pseudopodia. On Chaetomorplia crassa at Naples.
Boderia, Wright (Fig. 9), is marine, orange or brown in colour, with
a membranous investment (?), from openings in which protrude three to
four long branching pseudopodia. The nucleus or nuclei after a time
disappear, and the protoplasm spreads out in ragged masses on the slides.
A number of naviculoid bodies are formed, from each of which a small
amoebula emerges in a few days. Marine. 1-4 mm.
GROUP D.
Most of the genera included in this group form plasmodia, and their
affinities seem to be with the Mycetozoa. No plasmodium-formation has
been found in Aphelidium, Colpodella, Pseudosporidium, and Pseudamphi-
THE PROTEOMYXA
monas. Zoospores with one or two flagella have been seen in all the
genera except Myxodictyiim, Bursulla, and Tetramyxa. It is possible that
Colpodella is related to the Mastigophora.
(III.) Protomyxa (Fig. 6, 1) was found by Haeckel attached to the shells
of Spirilla on the coast of the Canary Islands, in the form of orange-yellow
flakes consisting of branching and reticular protoplasm nourishing itself
by the ingestion of Diatoms and
Peridiniae. This is a plasmodium
formed by the union of several
amoebulae. The plasmodium en-
cysts and gives rise to numerous
flagellulae or swarm-spores. The
diameter of the cyst is '12-'2 mm.
The flagellulae pass into an amoe-
bula phase, and the amoebulae
unite to form the plasmodium.
Myxodictyum, Haeckel, consists
of a number of protomyxa-like
individuals united by their pseudo-
podia to form colonies. It is
pelagic in habit and was found by
Haeckel at Algeciras in Spain.
Marine.
(II.) Gyinnococcus, Zopf, occurs
in Cladophora, Diatoms, and Gylind.ro-
spermum. It forms a plasmodium.
When fully fed it gives rise to zoo-
cysts, from which three to twelve
biflagellate zoospores escape.
(II.) Aphelidium, Zopf, lives in
the cells of Colenchaeta and in macerations of plant tissues. Hypnocysts
furnished with an operculum are formed. A nucleated zoospore with
one flagellum has been found in A. lacerans (de Bruyne).
(II.) Protomonas, Cienkowski, has biflagellate zoospores which become
amoeboid and unite to form a plasmodium. Freshwater and marine.
(II.) Colpodella, Cienkowski (Fig. 8, A), is possibly allied to Protomonas.
The zoospores have only one flagellum, and attack Mastigophora before
they become amoeboid. They do not, however, form plasmodia.
(II.) Tetramyxa, Gobel, forms large galls on various water-plants,
especially Buppia.
(II.) Plasmodiophora, Woronin, is the cause of the disease of turnips
known as " Fingers and Toes," or " Hanburies " (German, Herniekrank-
heit). The spores are found in damp ground. Each spore gives rise to
a minute nucleated amoeboid zoospore with a single flagellum. This
penetrates into the cells of the root and loses its flagellum. It increases
in size and the nuclei divide. After a time plasmodium-formation begins
by the fusion of neighbouring amoebulae, and the tissues of the host-plant
disintegrate. As soon as the plasmodium is formed the nuclei increase
rapidly by karyokinesis, but according to Nawaschin (21) there is a period
Botleria turneri.
(After Wright.)
12
when the plasmodia exhibit no trace of nuclei, the nuclear substance being
apparently distributed throughout the whole plasmodium. Subsequently
the plasmodium breaks up into a great number of minute spherical
spores.1
Pseudamphimonas, de Bruyne, was found on Caulerpa at Naples. The
zoospores are biflagellate and extremely amoeboid. They withdraw their
flagellae, and two or three have been seen to fuse together to form a
plasmodium.
(I.) Bursulla, Sorokin, is found in horse-dung. A number of amoebulae
with long pointed pseudopodia unite to form a plasmodium. The
plasmodia contract and form either stalked cysts (51 /*,), the contents of
which divide and emerge as eight amoebulae, or they give rise to naked
spherical cysts with rosy contents and an outer cortex, from each of
which a single stalked zoospore emerges.
GROUP E.
The affinities of the genera included in this group are quite
obscure.
(I.) Enteromyxa, Cienkowski, forms, by the fusion of amoeboid zoospores,
long vermiform plasmodia (O'5-l mm.) with short tubercular pseudopodia.
These break up into segments, which encyst and give rise to two or
seldom more amoeboid zoospores. It feeds on Oscillatoria.
(I.) Endyonema, Zopf, forms cylindrical cysts of considerable length in
the threads of filamentous algae. Nuclei are said to occur previous to
cyst-formation.
Ectobiella, de Bruyne (Fig. 1), was found in the form of a biflagel-
late pyriform zoospore. It attacks Licmophora and other diatoms, with-
draws the flagella and pushes a pseudopodium into the protoplasm of its
prey. When the contents of the diatom are assimilated, the amoeboid
organisms wander away and encyst.
Haplococcus, Zopf, is found in the muscles of the pig. Two kinds of
cysts are described by Zopf, the zoocysts (1 6-22 /x) and the hypnocysts
(25-30 /A). The membrane surrounding the former is thinner in some
places than elsewhere, and from them escape six to fifteen amoeboid
spores. The further history of the hypnocysts has not been followed.
Pseudosporidium, Zopf, was found by Brass in vegetable infusions.
It is amoeboid in form, with short blunt pseudopodia, a nucleus, and a
vacuole. The cysts give rise to numerous small flagellate zoospores.
Schizogenes, Pouchet, was found in the haemocoel of freshwater Ostra-
cods and Copepods. It consists of small plastids of hyaline protoplasm,
•01-'03 mm. without vacuoles or nucleus, of indefinite form, and devoid
of pseudopodia. It divides into parts, which become new individuals.
BathybiuSj Huxley, and Protobathybius, Bessels, are no longer regarded
as living organisms. It seems probable that both forms represent a colloid
precipitate of calcium sulphate thrown down by the action of alcohol on
sea-water (Murray).
1 See Note, p. 4.
LITERATURE OF THE PROTEOMYXA 13
LITERATURE.
The following recent general works on Protozoology will be found useful to
students : —
1. Braun. Animal Parasites of Man. Translated by F. V. Theobald. 1906.
2. Biitschli, 0. Protozoa. Bronu's Klassen und Ordnungen des Thierreichs.
3. Calkins, G. N. Protozoa. Columbia University Biol. Series. 1901.
4. Cash, J. The British Freshwater Rhizopoda and Heliozoa, vol. i. Ray
Society, 1905.
5. Doflcin, F. Die Protozoen als Parasiten und Kraukheitserreger. Jena, 1901.
6. Hartog, M. M. Protozoa. Cambridge Natural History, vol. i., 1906.
7. Lamj, A. Lehrbuch der vergleichende Anatomic. Protozoa. 1901.
8. Penard, E. Faune rhizopodique du bassin du Leman. 1902.
The following refer particularly to Proteomyxa : —
9. Benedcn, E. van. Q. J. Micr. Sci. xi., 1871, p. 254.
10. Brass. Biol. Studien, i., 1883-4, p. 70. (Pseudosporidium.)
11. de Bruyne, C. Arch. Biol. x., 1890. (Ectobiella, etc.)
12. Cienkowski. Arch. mikr. Anat., 1865, 1876.
13. Dangeard, P. A. Le Botaniste, (2), 1890, p. 33, and (7), 1900, p. 131.
14. Gobel. Flora, No. '28, 1884. (Tetramyxa.)
15. Haeckel, E. Monogr. der Moneren. Jen. Zeits. iv., 1868.
16. System. Phylog. der Protist. u. Pflanzen. Berlin, 1894.
17. Ho'<genraad, II. K. Arch. Protist. viii., 1907. (Vampyrella.)
18. Mereschkowsky. Arch. mikr. Anat. xvi., 1879. (Monopodium.)
19. Monticelli. Boll. Soc. Napoli, xi., 1897. (Dictyomyxa.)
20. Murray, J. P. R. Soc. London, xxiv., 1876.
21. Nawaschin. Flora, 1899, p. 404. (Plasmodiophora.)
22. Rhumbler, L. Arch. Protist. iii., 1904.
23. Schneider, A. Arch. mikr. Anat. vii., 1878. (Monobia.)
24. Sorokin. Ann. Sci. Nat. Bot. (6) iii., 1876; Morph. Jahrb. iv., 1878,
( Gloidium. )
25. Topsent, E. Arch. Zool. Exper. (3) i., 1893. (Pontomyxa.}
26. Verworn. Arch. ges. Physiol. Ixii., 1896. (Rhizoplasma.)
27. West, G. S. J. Linn. Soc. Zool., 1901, xxviii. p. 308.
28. - - I.e., 1903, xxix. p. 108.
29. Woronin. Pringsheim's Jahrbiicher, xi. (Plasmodiophora.)
30. Wright, S. Journ. Anat. Physiol. i., 1867. (Boderia.)
31. Zojif, W. Handbuch der Botanik. Edited by A. Schenk. Bd. iii., pt. 2r
1887.
THE PEOTOZOA (continued)
SECTION B. THE HELIOZOA 1
THE term Heliozoa is commonly used to include a number of
Protozoa, generally inhabitants of fresh water, with few characters
in common except the possession of straight, radial pseudopodia
which rarely anastomose, and the absence of anything like a
capsular membrane dividing a central portion of the body from a
peripheral portion, such as is found
among the Eadiolaria. The more
highly specialised members of the
group have a spheroidal body, which
rarely exhibits amoeboid change of
shape, divided into a more vacuolated
FIG. 1.
Actinosphaerium Eichhorni, Ehrb. A, a drawing
of an individual as seen in optical section ; c.^i, a
contractile vacuole previous to discharge of its
contents ; c. vz, the position of a contractile vacuole
that has just collapsed ; e.r, food-vacuole ; r, a
rotifer in the act of being engulfed in a food-vacuole.
B, a small portion of the ectoplasm of the same
animal very much enlarged ; N, the nuclei ; ps, a
pseudopodium ; ps.a, the axis of the pseudopodium.
The axes of the pseudopodia have been recently
traced farther into the ectoplasm than is shown in
the figure and into closer relation with the nuclei.
(After Leidy.)
ectoplasm and a less vacuolated endo-
plasm, the endoplasm containing one
or many nuclei, and sometimes a per-
manent centrosoma distinct from the
nucleus. The pseudopodia are long,
slender, and stiff, projecting radially
from the surface of the body, and
generally consisting of a cortex con-
tinuous with the ectoplasm and an
axis prolonged into the endoplasm (Fig. 1, ps). In Elaeorhanis,
Nudearia (Fig. 8, E, p. 1 0), and some others that may be regarded as
being on the border-line between the Heliozoa and Group B of the
1 By the late Prof. W. F. R. Weldon, F.R.S., and Prof. S. J. Hickson, F.R.S.
14
THE HELIOZOA 15
Proteomyxa (cf. p. 6), no axial rod to the pseudopodium has been
discovered. A skeleton may be present or absent ; when present
it is generally siliceous, though it may be in part chitinous (Adino-
lophus), or composed of a jelly whose chemical composition is
unknown (Heterophrys), or built up of foreign particles (Elaeorhanis),
Hertwig and Lesser (7), in a memoir which established the
main lines of the modern classification of the group, included only
those higher forms whose characters have been indicated, giving a
conception of the Heliozoa both logical and in many ways con-
venient ; but such a treatment neglects a singularly perfect series
of forms, the higher members of which, such as Nuclearia (Fig. 8, E,
p. 10), closely resemble undoubted Heliozoa, while from these we
may pass step by step to such forms as Monobia or Vampyrella
(Figs. 4 ; 6 (5), pp. 4 and 7), which are probably more nearly allied
to the Mycetozoa than to the typical Heliozoa. We have here, in
fact, a case such as often occurs in which different types of structure
and life-history are connected by a series of intermediate forms so
gradual that any attempt to define the limits of either must fail.
Under these circumstances, the limits assigned to one or other group
in a descriptive classification depend merely on convenience ; the
only point of importance is to frame the classification in such a way
that it shall not disguise the real continuity of the forms described.
For this reason, most modern writers, while recognising the great
value of the conception formulated by Hertwig and Lesser, have so
enlarged it as to include among the Heliozoa a number of transi-
tional genera (p. 6).
For the sake of convenience, the forms that are included in the
Heliozoa in this article are those in which one or more definitely
formed nuclei are present during the vegetative phases of life,
together with those genera which seem to have the closest zoological
relation to them although their nuclei are not known. The
genera that are sometimes classified with the Heliozoa, mainly on
the ground that they have stiff radiating pseudopodia, but which
afford some • reasons for believing that their nuclei are dissipated
during the vegetative phases of life, are placed with the Proteomyxa
(see p. 6).
It will be convenient to consider first the structure of the more
highly specialised forms to which Hertwig and Lesser proposed
that the name Heliozoa should be restricted, and to discuss the
transitional genera afterwards.
The characters of the more specialised Heliozoa may be illustrated
by describing Adinophrys sol, the common freshwater species already
mentioned. The body is spheroidal and minute, rarely exceeding
0'05 mm. in diameter ; in a healthy undisturbed individual numerous
stiff pseudopodia, each considerably longer than the diameter of the
body, radiate from the surface. The body itself is divided into a
THE HELIOZOA 17
clearer coarsely vacuolated ectoplasm, and a less transparent spongy
or feebly vacuolated endoplasm, containing a centrally placed nucleus
(Fig. 2(1), d). The ectoplasm is normally so crowded with vacuoles
that it is reduced to a mere system of septa, and to a thin layer form-
ing the cortex of the radial pseudopodia. During the ingestion of
food, however, an aggregation of ectoplasm takes place, forming a
short, blunt amoeboid projection by which the food is engulfed, and
in which a digestive food-vacuole is formed (Fig. 2(1), a). The ecto-
plasm usually contains a number of bright, highly refringent granules,
remarkably uniform in diameter, which are carried from one region
to another by streaming movements of the protoplasm ; thus they
may often be seen streaming to or from the apex of a radial pseudo-
podium, or towards the apex on one side and away from it on the
other. The number of these granules is said to increase with
increased nutrition, but their chemical nature is quite unknown.
FIG. 2.
1, Actinophrys sol, Ehrb., x 800; o, food-particle lying in a large food-vacuole; 6, deep-
lyiii^' finely granular protoplasm ; c, axial filament of a pseudopodium extended inwards to the
nucleus ; d, the centrally placed nucleus ; e, contractile vacuole ; /, superficial, much-vacuolated
protoplasm. 2, Clathrulina elegans, Cienk., x 200. 3, Heterophrysmyriopoda, H. and L., x 660 ;
a, nucleus ; 6, clearer protoplasm surrounding the nucleus ; e, the peculiar felted envelope.
4, Rhaphidiophrys pallida, V. E. Schultze, x 430 ; a, food-particle ; b, a contractile vacuole (?),
the nucleus is probably represented by the circular shaded body lying below 6 ; c, a food-particle ;
rf, the centrosome. The tangentially disposed spicules are seen arranged in masses at the
surface. 5, Acanthocystis turfacea, Carter, x 240 ; a, probably the centrosome ; b, clear pro-
toplasm around the centrosome ; c, more superficial protoplasm with vacuoles and xanthellae ;
d, coarser siliceous spicules ; e, finer forked siliceous spicules ; /, finely granular layer of
protoplasm. The long pseudopodia stretching beyond the spicules are not lettered. 6, biflagellate
"flagellula" of Acanthocystis acideata; a, nucleus. 7, Flagellula of Clathrulina elegans; «,
nucleus ; b, granules of uncertain composition. 8, Astrodisculus radians, Green0, x 320 ; o, red-
coloured fatty globule ; 6, peripheral homogeneous envelope. (From Lankester, after various
authors.)
The endoplasm is rarely vacuolated, and the bright refringent
granules are absent from it.
In a normal pseudopodium we can distinguish (1) a cortical
layer, and (2) an axial filament. The cortical layer is continuous
with the general ectoplasm at the base of each pseudopodium ; it is
irregular in thickness, and may by a streaming movement become
aggregated into amoeboid droplets of relatively large size during
the seizure of prey (Fig. 2 (3)). The effect produced upon infusoria,
small rotifers, and other ciliated organisms by contact with the
pseudopodia is a marked paralysis, which has led many observers,
from Ehrenberg onwards, to assume that some poisonous substance
is formed by or contained in the cortex; but direct chemical
evidence of this is wanting. The axial filament is a clear homo-
geneous thread, which runs from the apex of a pseudopodium
through the substance of the body, to end in a central dilatation in
contact with the nuclear membrane. When a pseudopodium is
withdrawn, its axial filament disappears, and cannot be demon-
strated by staining reagents ; in the living animal it is more easily
1 8 THE HELIOZOA
seen at some periods than at others, and may even for a time dis-
appear without retraction of the pseudopodium.
The nucleus is relatively large, with an obvious, doubly -con-
toured membrane. Within the membrane is a fine reticulum of
" linin " threads, on which are small particles of chromatin ; there
is generally also a single large extra-reticular mass of chromatin,
forming a karyosomatic "nucleolus."
The vacuoles are of three kinds : non-contractile and contractile
vacuoles which do not contain food-particles, together with diges-
tive vacuoles which contain food. The non- contractile vacuoles
form a layer occupying the whole thickness of the ectoplasm ; they
contain a clear, colourless fluid, in which refringent granules, like
those found in the ectoplasm, may often be seen floating, the number
of such granules in a single vacuole being sometimes large. A
non-contractile vacuole, which contains many granules, sometimes
bursts, and the granules are scattered in the surrounding water.
There is generally only one contractile vacuole, which rhythmically
changes, enlarging slowly until its diameter may be about half that
of the body, and then suddenly collapsing ; the cycle of dilatation
and contraction is completed, at ordinary temperatures, in about
one minute (40-100 seconds, Penard [14]). The function of the
contractile vacuole is as obscure in this as in other cases. Most
observers believe that the fluid, collected during dilatation, is
expelled from the body during contraction of the vacuole, so that
the whole process is excretory in nature ; but while it is difficult to
watch an Adinophrys without sharing this opinion, it is equally
difficult to demonstrate its truth. The contraction takes place so
quickly that it is impossible to be sure whether a rupture of the body-
wall occurs or not ; and all attempts to show that the collapse of
the vacuole is accompanied by a disturbance in the surrounding
water, such as would result from the forcible expulsion of its con-
tents, have hitherto failed.
Food-vacuoles are formed in the blunt processes of the ectoplasm
already described. When fully formed they contain a clear fluid,
surrounding the ingested food-mass, which doubtless contains some
solvent in solution, analogous to those demonstrated in the similar
vacuoles of amoebae and of ciliata. Formed immediately beneath
the surface of the body, the food -vacuole remains throughout
its whole existence in the ectoplasm, where the processes of diges-
tion and absorption are completed ; a vacuole with a large food-
mass may, however, travel into the deeper parts of the ectoplasm.
After digestion is completed the residue of the food -mass remains
in the vacuole for some time, being ultimately discharged by the
bursting of the vacuole at some part of the surface of the body.
The food consists of living organisms, animals and plants.
Smaller prey is seized by the blunt ingestive processes alone, with-
THE HELIOZOA 19
out help from the radial pseudopodia ; a larger creature is seized by
a group of radial pseudopodia, which converge round it, generally
(always ?) losing their axial filaments, and send out amoeboid
processes, which more or less completely engulf the prey. The
mass formed by these fused processes and the organism they con-
tain travels towards the body, where it meets and fuses with an
ingestive process.
Actinoplirys is capable of performing various rolling or creeping
movements on the bottom of the pond, but the creature spends
much of its time suspended in the water, where it has a certain
power of rising and of sinking, though the way in which this is
effected is altogether obscure.
At intervals Adinophrys may withdraw its pseudopodia, the
axial filaments of which disappear ; it may then secrete a complex
cyst of two layers — an outer, fairly thick transparent layer of gela-
tinous consistence, within which is a second, thinner layer. ' After
the formation of these layers, the vacuoles disappear, the contractile
vacuole being the last to go, and the whole body shrinks. The
nucleus now divides mitotically (cf. infra, pp. 25-27), and the cyst
divides into two, each of which becomes spherical. Within each
of the resulting cysts a third hard, opaque membrane is secreted,
and a period of quiescence ensues, after which the walls are ruptured
and the creature emerges, new pseudopodia being rapidly formed.
This account is based on that given by Schaudinn (17), who says
that each daughter- cyst may divide again before entering on a
period of quiescence ; on the other hand, many observers describe
a process of encystment which is not accompanied by any division
whatever.
Just as encystment may occur without fission, so fission may,
according to Schaudinn, occur without encystment. An individual
about to divide in this way withdraws its pseudopodia, and a
peculiar mitosis takes place, not accompanied by disappearance of
the nuclear membrane or by the formation of centrosomata (infra,
p. 28) ; this is followed by fission of the cell-body, and pseudo-
podia are shortly afterwards emitted.
The processes of fission just described, whether accompanied by
encystment or not, are asexual, since there is no previous fusion
of individuals or of nuclei. A process of plastogamic fusion, involv-
ing the union of a number of individuals (as a rule by the ectoplasm
only), without nuclear fusion, frequently occurs. The number
of individuals so united is frequently two; but it may be over
thirty (Schaudinn). Plastogamic individuals lose their pseudo-
podia on the surfaces by which they are attached to each other
but retain them elsewhere, and the union is not necessarily followed
by a period of quiescence. Individuals which have been united in
Jbhis way for some time may separate without withdrawing those
20 THE HEL1OZOA
pseudopodia which they retained during the plastogamy. Schaudinn
thinks it probable that all recorded cases of division without mitosis
and without retraction of the pseudopodia are really cases in which
plastogamic individuals have been seen to separate.
An observation recently made by Calkins on Paramecium suggests
a possible eft'ect of plastogamy. The work of Maupas has shown
that, after a certain number of asexual divisions, Paramecium and
other Ciliata, when grown in artificial culture-media with a constant
supply of food of one kind, exhibit phenomena of degeneration,
which quickly lead to the death of the whole culture, unless
individuals produced by another zygote are introduced. If such
individuals are introduced, plastogamy occurs, which is quickly
followed by a complicated sexual (karyogamic) process ; and after
this the "rejuvenated" culture can enter upon another period of
asexual multiplication (cf. Chap. I. Fasc. II. pp. 386, 387). Calkins
has, however, shown that a culture which exhibits signs of degenera-
tion may be completely "rejuvenated" by purely chemical stimuli,
such as an appropriate change of food, and that if plastogamy alone
be allowed to occur, the conjugating individuals being shaken apart
before the nuclear changes which precede karyogamy have taken
place, these individuals can still go through a further cycle of
asexual divisions. Nothing analogous to the phenomena of
"senile degeneration" described by Maupas has been observed
among the Heliozoa, but it is possible that it may occur, and that
the rejuvenescent effect of natural plastogamy is similar to that of
the artificial plastogamy observed by Calkins.
Although plastogamy is often followed by a complete separation
of individuals, it may be the beginning of a sexual karyogamic
process, which has been carefully studied by Schaudinn. In this
case the mass of individuals, united by ectosarc, sinks to the bottom
of the water; the pseudopodia are withdrawn, and a common
gelatinous cyst is secreted, like the outer layer of a solitary cyst.
Each individual within the gelatinous common cyst secretes a
membrane, which is thrown into wrinkles, so that in optical
section it looks as if made of spicules joined together. These
cysts lie in pairs within the common jelly, the two members of a
pair in contact (Fig. 3). The nucleus of each cyst now goes
through a mitosis (infra, pp. 25, 27), which results in the extrusion
of a single polar body. When the pronuclei of a pair of adjacent
cysts have returned to the resting condition, the walls of the cysts
break down at the point of contact, the two cell-bodies fuse, their
pronuclei also fusing, and the completed zygote becomes spheroidal
within the membrane derived from the cyst -walls of the two
gametes. After a period of quiescence the nucleus of the zygote
divides into two, by a process identical with that observed in
asexual cysts, and the division of the nucleus is followed by that
THE HEL1OZOA
21
of the cell-body and of the cyst-wall. On emerging from the cyst,
after division, vacuoles and psetidopodia are developed, and the
adult condition is assumed.
The majority of the higher Heliozoa resemble Adinophrys in
general structure, though their appearance may be greatly altered
by the presence of a skeleton or by the formation of a stalk.
The modifications of the cell-body are chiefly those connected with
the greater or less development of vacuoles and of various coloured
substances. The division into ectoplasm and endoplasm is generally
obvious. The ectoplasm usually contains contractile vacuoles, which
VI.
Adinophrys sol. I, two free-swimming individuals in conjugation. II, the same individuals
in an early phase of encystment. The nuclei are considerably enlarged. Ill, formation of
the polar spindles. IV, stage with two reduced nuclei and degenerating polar nuclei. V,
the reduced nuclei have fused together and the polar nuclei have reached the periphery.
VI, the first segmentation spindle is formed and the polar nuclei are ejected as polar bodies.
i/-, cyst membrane; e.v, contractile vacuoles; N, nuclei; P.N, polar nuclei; P.B, polar
bodies ; P.Sp, polar spindle ; S.Sp, segmentation spindle. (After Schaudinn.)
may be very numerous (more than 20 in Acanthocystis). In
Actinosphaerium the system of non-contractile vacuoles is even more
highly developed than in Adinophrys, but in the skeletogenous genera
the non-contractile vacuoles are few. The ectoplasm is usually the
seat of digestion and assimilation, as it is in Adinophrys ; and usually
contains refringent granules, which may be rounded, like those of
Adinophrys, or crystalloid (Heteropkrys). Perhaps the larger coloured
granules which occur either in the ectoplasm or in the endoplasm, or
scattered throughout the body, belong to a different category from
the refringent granules ; large brown granules may occur in the
ectoplasm (Pinacocystis), brownish or yellowish bodies may be scattered
22 THE HELIOZOA
through the whole substance of the body (Pompholyxophrys, Rliaphi-
diophrys), and in a few forms (Elaeorhanis) a large coloured oil
globule is found in the endoplasm. In Actinosphaerium, where
digestion and assimilation occur in the endoplasm, that region of the
body is crowded with brownish refringent granules, leaving the ecto-
plasm relatively free. A few of the larger coloured droplets have
been described as fatty ; but the chemical nature of most of these
coloured bodies is quite unknown.
Chlorophyll associated with differentiated chloroplasts is found
either in the endoplasm (some varieties of Actinosphaerium Eichhornii)
or in the ectoplasm (Rhaphidiophrys, Heterophrys, etc.). The nature and
origin of these bodies have been much debated ; some writers have
regarded them as the remains of green animals or plants ingested
as food ; Archer and Greeff maintained that they were in many
cases, at least, formed by the Heliozoa in which they were observed.
There can be little doubt, however, that they are in some cases at
least of the same nature as the Xanthellae that occur in Radiolaria
(see p. 97) and in Trichosphaerium among the Lobosa, and that
they are therefore independent organisms living in association with
the Heliozoa, and are not, as has been suggested, of endogenous origin.
Although we have at present very little information concerning the
history of these organisms in the Heliozoa, the observations of
Penard on green varieties of Actinosphaerium lend strong support
to this suggestion. This author found that the green cells are oval
in shape, 7-10 //, in length, and surrounded by a clear gelatinous
membrane. They possess a bell-shaped chromatophore, a spherical
pyrenoid, and in some cases a vacuole at one end. On crushing
the Actinosphaerium, these cells escape, and subsequently protrude
first one and then a second very delicate flagellum. He believes
the organism to be identical with the Palmellacean Alga Sphaero-
cystis Schroteri (Chodat). In other cases he has seen a large number
of flagellate organisms belonging to the genus Chlamydomonas
attached to the surface of an Actinosphaerium, and has shown that
they are actively attracted to the host. It is true that at present
it has not been proved that the Chlamydonionads actually enter the
ectoplasm of the Actinosphaerium and become the xanthellae ; but in
view of the proof recently published by Keeble and Gamble (10),
that the infecting organism of the Turbellarian Convoluta belongs to
the Chlamydomonadina, Penard's observation is very suggestive.
Awerinzew (1) has recently described the xanthella of Actino-
sphaerium as Zoochlorella actinosphaerii.
In addition to the xanthellae, other organisms are occasionally
found in the ectoplasm of the Heliozoa. Thus, a eiliate infusorian
allied to the genus Blepharisma has been found in as many as
30 per cent of the individuals of Rhaphidiophrys viridis found at
Bernex, and a rotifer attributed to the genus Monolabis by Archer
THE HELIOZOA 23
and to the genus Proales by Penard occurs in the ectoplasm of
Acanthocystis turfacca. It is probable also that the minute rods
that have been found in Acanthocystis turfacea (Leidy) and the
corpuscles in A. spinifera, Rhaphidiophrys viridis, and Heterophrys
myriopoda may be bacteria.
The structure of the pseudopodia is probably very constant in all
the higher forms. In Elaeorhanis, Nudearia, and Hedriocystis there
appears to be no axial filament. In Clathrulina elegans and in
Elaeorlumis they are sometimes bifurcated. In a Heliozoon allied
to Adinophrys, Crawley (5) has recently observed that the pseudo-
podia are arranged in tufts at the periphery, and may either
remain stiff and motionless like the typical pseudopodia of Heliozoa
or assume lashing movements like flagella or cilia. In Adino-
Sj'hacrium arachnoid-eum, Penard, the pseudopodia are very long,
branching, and capable of anastomoses.
The relation of the inner ends of the axial filaments of the
typical pseudopodia varies in a remarkable way with variation in
the position of the nucleus. In Actinosphaerium, where the
number of nuclei is very great (sometimes over 400), the axial
fibres end each in the neighbourhood of a nucleus, if not in actual
contact with its membrane, so that the relation is here similar to
that of Adinophrys. In a great number of genera, however, the
centre of the body is occupied by a deeply-staining granule first
discovered by Grenacher (6) and now known to behave like a
centrosome ; to this body the inner ends of the axial filaments are
attached (Fig. 6, A). There is never more than a single centrosome,
which may be associated with a single eccentrically-placed nucleus
(Acanthocystis, etc.) or with many nuclei (Gymnosphaera).
Skeletal investments of several kinds are found among the higher
Heliozoa. In Elaeorhanis the body is covered by an agglutina-
tion of diatoms, sand-grains, etc., loosely cemented together ; in
Heterophrys (Fig. 2 (3)) the body is surroupded by a finely granular,
transparent capsule, of gelatinous consistency and quite unknown
composition, soluble in strong acids ; this capsule is separated from
the ectoplasm by a considerable space, traversed only by the radial
pseudopodia, which emerge through perforations in its substance.
The outer surface of the capsule bears delicate radial spines, shorter
than the pseudopodia, which are regarded by Penard as being
chitinous in composition on the ground that they are soluble in
boiling sulphuric acid. In Actinolophus the greater part of the
body is naked, except for a short time before encystment ; but the
stalk, on which the body rests, is a tube of what appears to be
chitin, containing one or two thread-like prolongations of the body.
The greater number of skeletons are, however, siliceous, the silica
being deposited in the form of separate or loosely-articulated plates
or spicules (Chalarothoraca) or as a continuous basketwork (Desmo-
THE HEL1OZOA
thoraca). In the Chalarothoraca the siliceous particles may be
minute and spherical, lying close together and forming one or
several layers (Pompholyxophrys), or they may be elongated spicules,
or flattened plates. Spicules are of two kinds, the one kind curved
and pointed at each end, the other straight, pointed or bifurcate at
one end, flattened and expanded at the other. The curved spicules
are placed tangentially to the surface of the body, and may be the
only skeletal elements present (Ithaphidiophrys), in which case they
form a loose investment for the animal, from which groups of
spicules are occasionally carried up the pseudopodia by the
FIG. 4.
Heterophrys Fockei, Archer, c.c, contractile vacuoles. A nucleus is present in the centre
of the protoplasm, but is not'shown in the figure, s, radial chitinous (?) spines surrounding
the envelope. Several xanthellae are seen in the protoplasm. (After Hertwig and Lesser.)
streaming movement of the ectosarc (Fig. 2 (4)). In lihaphidocystis
some very remarkable funnel-shaped or wine-glass-shaped spicules
are found. In Acanthocystis both tangential scales and straight
spicules may be present, the latter being radially placed, with their
pointed ends outwards. There may be two kinds of these radial
spicules, a longer hollow kind with the free extremity bluntly
pointed, and a shorter solid kind with the free end forked (Fig. 2 (5)).
Siliceous plates, articulated together by their edges to form a
capsule round the body, occur in Pinacocystis and in Pinaciophora.
In Pinacocystis the pseudopodia emerge through the spaces between
the plates, but in Pinaciophora, according to Greeff, the plates are
perforated by fine pores.
THE HELIOZOA 25
In the Desmothoraca, of which Clathrulina is the best-known
genus, the skeleton has the form of a spherical basketwork, the
bars of which often show a median ridge on the outer surface, the
spaces between the bars being irregularly polygonal with rounded
angles (Fig. 2 (2)). This basketwork is supported on a long, hollow
.siliceous stalk.
The structure of the nucleus and the processes of hiryolcinesis
have been minutely described by R. Hertwig (8) in Actinosphaerium,
and his descriptions are in accord with what is known concerning
them in the higher Heliozoa generally.
The resting nucleus of Actinosphaerium has a definite membrane
.continuous with an internal achromatic network whose relation to
the chromatin elements is very variable. The whole of the
.chromatin may be collected into a relatively large mass, supported
in a matrix of achromatic substance ("plastin") and forming a
conspicuous " karyosomatic " nucleolus ; such a condition of the
nucleus may be induced by starvation, or it may appear as a pre-
liminary to division. In well-fed individuals the chromatin spreads
through the nucleus in the form of coarse branches or networks.
Nuclear division may be direct, in the formation of buds or
swarm -spores, or by karyokinesis. Karyokinesis occurs in the
division of the nuclei within the body of the multinucleate forms
(e.g. Actinosphaerium) without being followed by division of the
body ; in forms with a single nucleus it occurs during fission, and
during the maturation of the conjugants (gametocytes).
In Actinosphaerium there are three kinds of karyokinesis, that
differ from each other in some details of considerable theoretical
importance. In the nuclear divisions of the unencysted body no
£entrosomes are formed, and the spindle is considerably compressed
between the two poles. In both the mitoses of the maturation of the
gametocytes, centrosomes occur at each pole of the spindle, but in
the first (polar) division the chromosomes are larger than in the second
.(polar) division, and there are some other differences in detail of
minor importance. In all three kinds of karyokinesis there are
numerous chromosomes (about 150), and both the divisions of the
nuclei in the maturation of the gametocytes are of the nature of "equa-
tion " divisions, the number of the chromosomes not being reduced.
It may be convenient to describe in greater detail the second
polar division of Actinosphaerium as an example of the karyokinesis
of the Heliozoan nucleus. At the end of the first polar division,
one of the resultant nuclei degenerates and is ultimately ejected
with the first polar body, the other remains in the centre of the
protoplasm and passes through a short period of rest. At one
pole of this resting nucleus there is a clearly-marked centrosome
surrounded by a small aster. Antecedent to the second polar
division the centrosome diminishes in size (Fig. 5, I, c), and
26
THE HELIOZOA
subsequently divides into two parts, which travel to opposite poles
of the nucleus. The nucleus now begins to increase considerably
in size, and is seen to contain several large chromatin bodies which
certainly contain both chromatin and plastin derived from the
nucleoli (Fig. 5, II). The centrosomes at each pole of the
nucleolus are of considerable size and more conspicuous than at
any other time in the divisions of the three kinds of karyokinesis.
The chromosomes are now formed by a breaking down of the
-^v
@\. .
jsfgpF
iv:
~"— -~^c
••vV^
*V:-:- *t~3:i.i.1il
FIG. 5.
Actinosphaeriitm. Formation of the second polar spindle. I, the nucleus after the first
polar division, the centrosome (c) reduced in size previous to the formation of the second
polar figure. II, the same nucleus at a later stage with two centrosomes. Ill, IV, V, VI,
VII, stages in the formation of the second polar nucleus. (After R. Hertwig.)
chromatin masses, and gradually assume an equatorial position.
They are at first very irregular and angular in shape, but ultimately
become rod-shaped, constrict in the middle, and divide transversely.
The spindle fibres seem to be formed from the achromatic network,
and several plastin remnants remain in the nucleus during ther
formation of the chromosomes. The chromosomes now travel
towards the opposite poles of the spindle in the usual way
(Fig. 5, VI), and subsequently become arranged in a fan-shaped
manner at the extremities of the now elongated spindle. According
THE HELIOZOA
27
to Hertwig (8) the chromosomes of the second polar division are
only half the size of the chromosomes of the first division, and
there is, therefore, a reduction in the mass of the 'chromosomes,
although there is apparently no reduction in their number.
The karyokinesis of the nuclei of the ordinary unencysted
Adinospliaerium differs from that just described principally in the
fact that no centrosomes are present. The first sign of commencing
division in these nuclei is the accumulation of a clear mass of
nearly homogeneous protoplasm at each pole ; the nucleus becomes
B.
C.
Fio. 6.
A, Acanthocystis aculeata, H. and L., in the living condition, with expanded pseudopodia.
N, the nucleus ; c, the centrosome. B, C, D, B, F, successive stages in the mitoticldivision of
the nucleus as seen in preparations. (After Schaudinn.)
flattened so that the diameter which passes through the proto-
plasmic masses is the shortest, and at each end of this diameter an
accumulation of achromatic nuclear substance is formed, giving rise
to what Hertwig calls the " polar plates."
In Acanthocystis the nucleus is situated excentrically, and con-
sists of a central deeply -staining body, the " pseudonucleolus,"
surrounded by an area which certainly contains a linin network
but much less chromatin. At the exact centre of the endoplasm
there is a small body which exhibits radiating lines which
appear to extend outwards and be continuous Avith the axes
of the pseudopodia (Fig. 6). This body, originally described by
28
THE HELIOZOA
Grenadier (6) as the " Centralkorn," has been proved by
Schaudinn to be a true centrosome. It has been discovered to
be a permanent of the body in llhaphidiophrys, Adinolophus, Hetero-
phrys, and Sphaerastrum. Before division of the nucleus it divides
into two equal parts, which take a position at opposite poles of the
endoplasm, each one surrounded by an aster of radiating lines. The
nucleus leaves its excentric position and becomes situated in a
direct line between the two centrosomes. The nuclear mem-
brane then fades away and a party of numerous small chromo-
somes occupy a position of an equatorial band on the spindle that
Fio. 7.
A, B, C, direct amitotic division of the nucleus of Acanthocystis aculeata as seen in the
process of the formation of buds. U, a colony of Acanthocystis formed by the gemmation of
a single individual. Only two individuals of the colony exhibit a centrosome, and these have
been formed by division, with nuclear mitosis, of the primary individuals ; the others have
been formed by gemmation without nuclear mitosis. E, a single bud freed from the
colony. F, a flagellula. G, an amoeboid spore. (After Schaudinn.)
is formed from the linin of the nucleus. The subsequent phases
of the nuclear division resemble those of the typical karyokinesis
of the metazoan cell.
* In the formation of the buds of Acantlwcystis the nucleus divides
directly and the centrosome remains unchanged (Fig. 7, A, B).
The buds are therefore for a time without any centrosome, but
this body is formed afresh in the buds from the nucleus. (See
Part I. Fasc. II. Fig. 20, p. 41.)
Reproductive Processes. — Probably all the higher Heliozoa are
capable of fission, preceded or not by encystment, although the
process has not been observed in all. The division of the nucleus
THE HELIOZOA 29
is mitotic, and is probably of the type observed in adult Actino-
spliaerium or of that seen in Acanthocystis, according to the presence
or absence of a permanent centrosome.
Budding has been observed in several cases ; and the process
has lately been described in detail by Schaudinn (19) in Acantho-
cystis. The nucleus divides directly once or several times, so that
the body may contain a considerable number of nuclei ; during
this process the pseudopodia are not withdrawn, the centrosome
and the system of axial filaments remaining unchanged. One of
the nuclei resulting from this division remains in the body of the
parent without further change ; each of the others travels into a
small projection from the surface of the body, which is the future
bud. Every bud is covered with a layer of spicules derived from
the parental skeleton, but it contains no centrosome, nor any trace
of radial fibres. The buds so formed may behave very differently
in different cases, and there is at present no knowledge of the
circumstances which determine their behaviour. A bud may
separate from the parent in the condition described, and may
divide one or more times, the products of division going through a
short resting stage before emitting pseudopodia ; or the resting
stage may occur immediately after the bud leaves the parent, in
which case it does not divide before assuming the adult condition.
In these cases there is nothing like " spore-formation " ; but a bud
may become amoeboid, and creep out of its skeletal investment,
either before the skeleton has separated from the parent or
immediately afterwards ; and such an amoebula may creep about
for a day or two, by means of blunt pseudopodia, before it becomes
spherical and secretes new spicules ; or, division of the nucleus may
occur within the bud, so that several amoebulae leave it, instead of
one. Lastly, an amoebula, at the moment of leaving the parental
skeleton or soon afterwards, may develop two flagella, by means of
which it swims for a short time ; such " flagellulae " quickly
become amoeboid and creep about for a further period as amoe-
bulae, before becoming spherical. None of these buds or spores are
known to conjugate, and indeed the origin of sexual spores by an
amitotic division would be remarkable ; but, however they behave in
the meantime, about the fourth or fifth day after emission each of
them becomes spheroidal, and secretes a skeleton of small tangential
spicules, which are first formed in the immediate neighbourhood of
the nucleus, and afterwards travel to the periphery. The centro-
some arises from the nucleus (Part I. Fasc. II. Fig. 20, p. 41), and
after it is established the axes of the radial pseudopodia appear.
The formation of "swarm -spores" was first described by
Cienkowski (4) in Clathrulina ; it was more recently discovered by
Schaudinn (19) in Acanthocystis ; and it may occur in Adinophrys
(Penard).
THE HELIOZOA
Sexual (karyogamic) processes have only been observed in
Actinophrys and in Actinosphaerium ; the process in Actinophrys
has already been described ; the phenomena observed in Actino-
Actinosphaerium. A, a mother-cyst just before it breaks up into primary cysts. The
nuclei are considerably reduced in number and the protoplasm contains numerous small
oval yolk-plates, y.p. B, the primary cysts have each divided into two secondary cysts. The
sister-cyst of a is not seen in the figure. N, nuclei ; c.m, mother-cyst membrane ; c.m%, cyst
membrane of the first order. (After Brauer.)
sphaerium are in many ways remarkably different. The first indica-
tion of approaching karyogamy is the encystment of a single
individual. The pseudopodia are withdrawn, their axial filaments
THE HELIOZOA 31
are absorbed, and the animal sinks to the bottom of the water,
where it exhibits considerable amoeboid movement, sometimes
giving out slender pointed pseudopodia which have no axial
filaments ; food-particles are ejected, and a thick, transparent cyst
is formed. This " mother-cyst " is of gelatinous consistence, sticky
on the outside, and its substance is deposited in concentric layers.
The peripheral vacuoles disappear after encystment, and numerous
peculiar oval discs, probably consisting of reserve food- material,
appear; these bodies may be called "yolk-plates" (Hertwig).
While the yolk -plates are forming, the number of the nuclei
diminishes, until not more than one -twentieth of the original
number remain. The process by which this reduction is effected
is not quite clear; Schneider and more recently Brauer (2)
have described a fusion of nuclei during the reduction; and
Brauer's figures of this fusion are very convincing ; Hertwig,
although he considers it not improbable that such a fusion occurs,
has never been able to demonstrate it. When the reduction in the
number of nuclei is completed, the body divides into as many
pieces as there are nuclei, each piece containing a single nucleus.
Every result of this division is enclosed in a siliceous " primary
cyst," largely formed by rearrangement of scattered spicules
secreted before division. The number of primary cysts varies
from one to thirty-five ; and Smith (20) has recently shown
that there is an interesting relation between the number formed
and the temperature at which encystment occurs ; at high tempera-
tures the number is smaller and the cysts are larger ; at low
temperatures the number of cysts is greater and their diameter
less. Smith also shows that the quantity of chromatin contained
in the nuclei of primary cysts formed at a low temperature is
greater than that found in cysts formed at higher temperatures.
Shortly after its formation, each primary cyst divides into two;
the nucleus behaves in essentially the same way as dividing nuclei in
the unencysted form (cf. p. 25) ; the number of chromosomes is very
large, and is estimated by Hertwig at from 130 to 150. The
secondary cysts, formed by the division of each primary cyst, now
behave like gametocytes ; a centrosome is extruded from the
nucleus, and a nuclear division occurs, leading to the extrusion of a
first polar body. After the extrusion of the first polar body, the
nucleus enters into a resting stage, a single centrosome remaining
outside it ; a second division now occurs, leading to the formation
of a second polar body, which is in turn extruded. The chief
points of interest in the formation of the polar bodies are (1) the
similarity of the process of formation, so that neither division can
'be called a "reducing division"; and (2) the very pronounced
resting stage which intervenes between them.
After the extrusion of the polar bodies, the two gametes,
32 . THE HELIOZOA
formed from the products of the division of a single primary cyst,
fuse again into a single zygote, their pronuclei uniting to form a
single fertilised nucleus. After this process is completed, a
membranous or gelatinous layer is formed within the siliceous
cyst, which Hertwig compares to the yolk-membrane so frequently
formed by fertilised ova. A multiplication of nuclei now occurs
within the cyst ; the creature becomes amoeboid, and emerges.
After emergence, individuals with a single nucleus are not very
rare, so that the amoeboid young may possibly sometimes divide ;
but the process has not been observed.
If the foregoing account be correct, we have in Actinosphaerium
the only case in the whole animal kingdom in which self-fertilisa-
tion is shown to be of normal occurrence. There are, however,
several points to be considered before this view can be adopted
without qualification. Brauer (2) asserts that the formation of
Hertwig's " primary " cysts is preceded by a fusion of nuclei, so
that the nucleus of each primary cyst is really formed from two
resting nuclei, confirming the view put forward by Anthon Schneider
in 1877 ; and Hertwig admits that there is a considerable body
of evidence in favour of this view, though if such a fusion takes
place it must be a very rapid process, affecting all the nuclei
in the body simultaneously ; otherwise its occurrence must have
been frequently witnessed by an observer so skilful and patient
as Professor Hertwig. The frequent occurrence of plastogamy
between adult individuals makes it very possible that all the nuclei
in the same body may not be of the same origin ; and therefore
the formation of the primary cyst- nuclei by the fusion of two
others might, in many cases, at least, mean the fusion of nuclei
originally produced in different individual bodies (Schaudinn).
Such a preliminary fusion of the nuclei of gametocytes, which
separate before giving off polar bodies and finally fusing to form
a zygote nucleus, has been observed in Spirogyra (cf. Klebahn [11],
quoted by Hertwig) ; and a process of a similar kind — a fusion
of gametocyte nuclei before the extrusion of polar bodies, the polar
bodies being only given off after division of the fertilised zygote —
appears to occur in some desmids (Closterium, Klebahn [11]). If,
therefore, we can believe that an individual before encystment has
normally exchanged some of its nuclei for those of another indi-
vidual during an antecedent plastogamy, and that a fusion of nuclei
in pairs takes place before the formation of the "primary" cysts,
the nuclear history of Actinosphaerium will not be without parallel ;
but there is direct evidence that normal encystment may occur
without plastogamy, since Hertwig has succeeded in keeping an
isolated individual under control through the entire period from
" hatching " until the production of normal, fertile cysts. Again,
all observers are agreed that plastogamy is not necessarily followed
THE HELIOZOA 33
by encystment Avithin any definite period, and Hertwig has obtained
cysts from individuals in which it had certainly not occurred for
several weeks.
CLASS HELIOZOA, HAECKEL.
ORDER 1. Aphrothoraca, Hertwig.
Heliozoa usually devoid of a skeletal or gelatinous envelope. A
membranous envelope, sometimes with siliceous spicules, is only developed
during encystment.
Genera — Actinophrys, Ehrb. ca. 50 p. Cosmopolitan in fresh water
and probably cosmopolitan in the sea (Fig. 2). Camptonema, Schaud.
Numerous small contractile vacuoles and about 50 nuclei. 120-180 p..
Marine, Norway. Actinosphaerium, Stein (Fig. 1). Two or more large con-
tractile vacuoles, numerous nuclei. 1 mm. Cosmopolitan in fresh water.
Gymnosphaera, Sassaki. Numerous nuclei. Very numerous and very long
pseudopodia. 140 /x. Pseudopodia up to 800 p. in length. Actinolophus,
F. E. Schultze. Body usually pear-sheaped. One nucleus. Pseudopodia
long and thin. Sometimes (always t) with a thin gelatinous membrane
perforated by the pseudopodia. Attached to a foreign object by a long
hollow stalk. Body 30 p. in diameter. Stalk 100 p, long by 3-4/4 in
diameter. Marine. North Sea. The genus Actinosphaeridium, Zacharias,
freshwater, Germany, is closely related to Actinolophus. The genera
Zooteirea, Wright, an oval form with a contractile stalk, from the
Firth of Forth, EstrMa, Frenzel, and Phythelius, Frenzel, are imper-
fectly known. Phythelius is probably an Alga. Nuclearia (see p. 8),
Cienkowski, differs from the other Heliozoa in having an amoeboid
body and pseudopodia without any definite axis. It is sometimes
regarded as a Proteomyxan. Myxodiscus crystalligerus is a form that is
doubtfully placed among the Heliozoa. It was found by Prowazek in a
sea-water aquarium. The genus Archerina, Lankester, which has been
regarded by some authors as a Proteomyxan and by others as a Heliozoon,
is now placed by Lankester (1 2) among the Algae. It is the same genus as
Golenkinia (Chodat.), belonging to the Pleurococcaceae, the naked proto-
plasm surrounding the green organism in many instances observed and
figured by Lankester being that of a Vampyrella-like or amoeboid
organism symbiotic with or merely crawling on the alga.
ORDER 2. Chlamydophora, Archer.
Heliozoa with a soft mucilaginous envelope, but without any solid
skeletal elements.
Astrodisculus,Greeft (Fig. 2(8)). Body spherical. Pseudopodia very long
and delicate. Several species recently described by Penard. Freshwater.
20-40 p. The genus Heliophrys, Greeff, is evidently closely related to
Astrodisculus, but has also been placed with Heterophrys (see West [21]).
The form described by Greeff as Chondropus viridis is regarded by Penard
as a peculiar species of Vampyrella,
3
34 THE HELIOZOA
ORDER 3. Chalarothoraca, Hertwig and Lesser.
Heliozoa with a loose envelope consisting of isolated siliceous or
chitinous spicules bound together by a mucilaginous or protoplasmic
matrix.
Heterophrys, Archer (Figs. 2 (3) and 4). A granular envelope containing
very delicate and indistinct chitinous spicules. One nucleus and one or more
contractile vacuoles. 10-20 p.. Freshwater (or marine ?). Sphaerastrum,
Greeff. According to Penard (14) this genus represents a species of
Rhaphidiophrys. Elaeorhanis, Greeff. The endoplasm contains a large
yellow or brown oil -globule. Envelope with attached sand -grains and
diatoms. 50 /*. Freshwater. Lithocolla, F. E. Schultze. No definite
oil-globule. Envelope with numerous siliceous bodies, for the most part
adventitious diatoms, and amorphic grains. Often united together in
colonies by a gelatinous matrix. 38-45 p-. Freshwater and marine.
Lithosphaerella, Frenzel. Envelope covered with several layers of sand-
grains. Freshwater (Argentine) and marine (Mediterranean). All the
genera so far mentioned were placed by Schaudinn (18) and others in the
Order Chlamydophora, but were transferred to the Order Ohalarothoraca
by Penard.
The following genera have isolated siliceous skeletal spicules and
are regarded as more typical of the Order. Pompholyxophrys, Archer =
Hyalolampe, Greeff. Skeleton composed of minute spherical pearls of
silex. 40-50 JJL. Freshwater. Pinaciophora, Greeff. Skeleton con-
sisting of overlapping circular plates. 50 p.. Freshwater. The genus
Pinacocystis, H. and L., which is said to be marine, is closely related to
Pinaciophora. Rhaphidiophrys, Greeff (Figs. 2 (4) and 9). Skeleton consist-
ing of a number of minute needles, spindles or half-rings arranged loosely,
tangentially, and radially in a protoplasmic envelope. This genus con-
tains several species and is widely distributed in fresh water. It is
often found in colonial groups. Freshwater and marine (A. pelagica,
Ostenfeld [13]). Rhaphidocystis, Penard. Spicules of various forms, but
always different from those of Rhaphidiophrys, scattered in a protoplasmic
envelope. 12-20 /JL. Freshwater. R. simplex = Acanthocystis simplex,
Schaudinn. Central Africa. Acanthocystis, Carter (Figs. 2 (5) and 6).
The envelope of siliceous spicules apparently continuous, formed of
tangential scales apparently touching one another and an armature of
radial needles. This genus contains a large number of species, widely
distributed in fresh water. Two species, A. italica and A. marina
(Ostenfeld), are marine. The genera Cierikowskia, Schaudinn, and
Wagnerella, Meresch., from the White Sea, differ from the others in
the possession of a stalk.
ORDER 4. Desmothoraca, Hertwig and Lesser.
Heliozoa provided with a continuous basket-like skeleton perforated
by holes.
Clathrulina, Cienkowski (Fig. 2 (2)). Apertures in skeleton relatively
large. Provided with a stalk. 70 /z. Freshwater. Hedriocystis, H.
THE HELIOZOA
35
and L. Apertures very small. Provided with a stalk. 20-30 \L. Fresh-
water. Elaster, Grimm. Apertures very numerous. No stalk. 20 p.
Freshwater. Choanocystis, Penard. Apertures provided with long funnel-
shaped collars. No stalk. 13 p.. Freshwater.
Fio. 0.
Rhaphidiophrys elcgans. Eight individuals united together by protoplasmic strands and
surrounded by a skeleton of half- rings. A nucleus is shown in one individual. (After
Jlertwig and Lesser.)
LITERATURE.
A very extensive list of works on Heliozoa will be found in the book by
Fenard (14). The following is a list of some of the priucipal books and papers
referred to in the text : —
1. Awerinzew, S. 0 zookhlorellakl u Prostyeishikh (On Zoochlorellae in the
Protozoa). Protok. St. Peterb. Obshch. xxxi. 1, No. 7 (1900), p. 322.
2. Brauer, A. Zeitschr. wiss. Zool. Iviii. (1894), p. 189.
3. Biitschli, 0. Bronn's Thierreich, Protozoa, 1880-82. This contains a biblio-
graphy up to the year 1879.
4. Cienkowski, L. Arch, inikr. Anat. iii. (1867).
5. Crawley, S. P. Ac. Philad. 54 (1902), p. 256.
6. Grenadier, H. Z. wiss. Zool. v. (1869), p. 259.
7. Hertwig, R., and Lesser, E. Arch. mikr. Anat. x. (1874), Supp.
8. Hertwig, R. Abh. k. bayer. Akad. Wiss. xix. (1898).
9. Test, von Haeckel (1904).
10. Keeble, F., and Gamble, F. W. Quart. J. Micr. Sci. li. (1907), p. 167.
11. Klebahn, H. Jahrb. wiss. Bot. xxii. (1890), p. 415.
36 LITERATURE OF THE HELIOZOA
12. Lankester, E. R. On Archerina, Golenkinia, and Botryococcus. Quart. J.
Micr. Sci. lii. (1908), p. 423.
13. Ostenfeld, C. H. Meddel. Komm. Havundersog. Kobenhavn.
14. Penard, E. Heliozoaires d'eau douce. Geneve (1904).
15. Prowazek, S. von. Arb. Inst. Wien, xii. (1900), p. 294.
16. Schaudinn, F. S. B. Ak. Berlin (1894), (2), p. 1277. (Camptonema.)
17. Ibid. (1896), v(l), p. 83.
18. Das Tierreich. Heliozoa (1896).
19. Verb, der deutscb. zool. Ges. Bonn, vi. (1896), p. 113.
20. Smith, G. Biometrica, vol. ii. (1902), p. 3.
21. West, G. S. J. Linn. Soc. xxviii. (1901), p. 308.
'22. Ibid. xxix. (1903), p. 108.
THE PROTOZOA (continued)
SECTION C. — THE MYCETOZOA J
CLASS MYCETOZOA.
SUB-CLASS I. EUPLASMODIDA.
Div. I. ENDOSPOREAE.
COHORT I. AMAUROSPORALES.
SUB-COHORT A. CALCARINEAE.
Order 1. Physaraceae.
,, 2. Didymiaceae.
SUB-COHORT B. AMAUROCHAETINEAE.
Order 1. Stemonitaceae.
„ 2. Amaurochaetaceae.
COHORT II. LAMPROSPORALES.
SUB-COHORT A. ANEMINEAE.
Order 1. Heterodermaceae.
„ 2. Liceaceae.
„ 3. Tubulinaceae.
,, 4. Reticulariaceae.
„ 5. Lycogalaceae.
SUB-COHORT B. CALONEMINEAE.
Order 1. Trichiaceae.
„ 2. Arcyriaceae.
„ 3. Margaritaceae.
Div. II. EXOSPOREAE.
Order. Ceratiomyxaceae.
SUB-CLASS II. SOROPHORA.
Order 1. G-uttulinaceae.
„ 2. Dictyosteliaceae.
By J. J. Lister, F.R.S., Fellow of St. John's College, Cambridge.
37
38 THE MYCETOZOA
THE plasmodial and the spore-bearing phases in the life-history of
the Mycetozoa have long been known. Many of the generic names
date from the eighteenth century, and Fries enumerated 192
species in 1829.
By the earlier naturalists these organisms were classed, under
the names Myxogastres or Myxomycetes, with the Gasteromycetous
Fungi, to which the sporangia of the Endosporeae present in
miniature a considerable superficial resemblance. Although this
view of their relationship is now generally abandoned, its influence
may be traced in the names " capillitium " and " hypothallus "
which are still applied to structures present in the spore-bearing
stages of the Mycetozoa.
It was de Bary (1-3) who first worked out (1859-64) the main
features of the life-history, showing that the spore hatches out as
a naked protoplasmic body which assumes a flagellate form, that
this passes after successive divisions into an amoeboid form, and
that from the amoebae the large plasmodia arise.
Cienkowski (7) contributed (in 1863) the important observation
of the mode of origin of the plasmodia by the fusion of the
amoeboid swarm-cells.
De Bary showed how widely different, both morphologically
and physiologically, these organisms are, not only from the higher
fungi, but from all those included in the vegetable kingdom, and
clearly expressed the opinion that they should be regarded as
animals.
In the discussion of the relationships of the Mycetozoa which
followed the publication of de Bary's work, it was early recognised
that some of the simple organisms included in the large and ill-
defined group of the Monadina present phases comparable with those
of the Mycetozoa. Thus Protomonas amyli and P. parasitica, which
are parasitic in vegetable tissues containing starch, were found
by Cienkowski (8) to begin their development as flagellate swarm-
cells, and then to become amoeboid, in which stage they take in
or envelop starch grains, which they are able to digest. Later they
encyst ; the protoplasm withdraws from the undigested food and
breaks up into a fresh brood of swarm-cells. Moreover, fusion of
several individuals may occur in the amoeboid stage prior to
encystment. An encysted resting stage is also found in the life-
history.
With the object of introducing order into the heterogeneous
assemblage of organisms which were, at the time of writing, classed
as Monadina, Cienkowski proposed (5) to restrict this name to forms
which passed through a life - history approximating to that of
Protomonas.
The group, as thus limited, was regarded by him (8) as inter-
mediate between animals and plants, and presenting affinities in
THE MYCETOZOA 39
several directions ; among others with unicellular algae, the
Mycetozoa and such forms as Actinophrys. Of these alliances, that
with the algae is the least satisfactorily established by Cienkowski,
but that between the " Monadina " and the Mycetozoa has been
generally accepted by de Bary and later writers.
Zopf (24) considerably enlarged the "Monadina " of Cienkowski,
and in 1887 included them in the Mycetozoa, distinguishing the
forms here included, as the Eu-mycetozoa. This course is open to
objection on several grounds. The "Monadina" of Zopf appear
to be still a very heterogeneous collection of forms, and their
inclusion in the Mycetozoa tends to obscure the well-marked features
of this group. Further, though the affinity of some of the
Monadina with the Mycetozoa seems probable, others are as closely
connected with the Heliozoa, in which class the majority of them
are, in fact, included by Biitschli (4).1
Hence the limits of the Mycetozoa, as here understood, are the
same as those drawn by de Bary. They include (1) the Sorophora
of Zopf (the Acrasiae of Van Tieghem) ; (2) the remainder, and
great majority of the species, for which de Bary retained the old
name of Myxomycetes. The only objection to retaining this name
is that it is generally used as synonymous with Mycetozoa. The
term Eu-mycetozoa would have been preferable, but it is used by
Zopf to include the Sorophora. Delage and Herouard have applied
the name Euplasmodida to the higher group, a course which avoids
all confusion, and emphasises one of the chief characters which dis-
tinguishes it from the Sorophora.
In a more recent work (25) Zopf has included the Labyrinth uleae as
a sub-order of the Sorophora. He has shown that the singular network
described by Cienkowski in Labyrinthula, by which the individuals are
united, is pseudopodial in nature, and regards the whole colony as forming
a body of the nature of a plasmodiuni, to which he applies the name
thread-plasmodium. There appears to be no evidence, however, that the
term plasmodiuni is any more applicable to the colony of Labyrinthula
than it is to those, e.y., of Mikrogromia, or the colonial Radiolaria. The
actively parasitic habit, the entirely aquatic life, the defined shape of the
members of the colony, and the absence of any proof that it is formed
by fusion of individuals, keep Labyrinthula distinct from forms hitherto
included in the Sorophora. Penard (20a) has recently extended our know-
ledge of Chlamydomyxa, showing that the " oat-shaped corpuscles " are
not nucleated, and therefore not comparable with the fusiform bodies of
Labyrinthula ; and also that the contents of the cysts escape as flagellate
zoospores. Penard finds a great analogy between this genus and the
1 Whatever position is ultimately assigned to the " Monadina " of Cienkowski
and Zopf, it is desirable that this name for them should fall into disuse, for it is now
applied in zoological works to the simpler members of the Flagellata, in which the
flagellate and not the amoeboid stage is predominant in the life-history.
40 THE MYCETOZOA
Euplasmodida, a view which is by no means shared by the writer of this
article. The presence of chlorophyll bodies and the stiff little-branched
character of the pseudopodia are altogether foreign to the present group,
and here again the plasmodial nature of Ghlamydomyxa is far from being
established. Both these genera are in the present treatise dealt with
separately (pp. 274, 280).
In addition to the remarkable phenomena presented by the
plasmodium of the Euplasmodida, the characteristic and unique
feature of the Mycetozoa, as a group, is that belonging, as
the earlier stages of their life-history show them to do, to the
animal stock, and developing their sporophores and sporangia in
air, these structures have been differentiated into a series of
forms analogous with the sporophores met Avith among different
orders of fungi. So close is the resemblance in many cases, that
sporangial forms of each of the three main divisions have been
classified among the several orders of fungi : Dictyostelium
(Sorophora) among the Mucorinae ; Cemtiimyxa (Exosporeae) with
the Basidiomycetes Polyporus and Hydnum ; and various members
of the Endosporeae with the Gasteromycetes.
EUPLASMODIDA.
THE LIFE-CYCLE OF THE ENDOSPOREAE.
(a) The Swarm-Cell or Zoospore.
The spores of the Mycetozoa are produced not in water, as are
those of the Monadina (except Bursulla), but in air, and they are
able to retain their vitality in the dry state for as many as four
years, undergoing no apparent change except a collapse of the
spore owing to the shrinking of the
contents on drying. When carried
into water, they rapidly swell and
cv resume their original form, which is,
in nearly all species, spherical. As
they lie in water one or more contrac-
tile vacuoles make their appearance in
the protoplasmic contents, and after
a period varying from a few hours
FIO. i. to a day or two, the spore wall is rup-
The hatching of a spore of Fuligo septica. turecl, and the Contents slip OUt and
x 1100. a, spore; 6 and c, contents .. . . . . ,
emerging and undergoing amoeboid move- 116 tree in the Water a maSS OI Clear
^ore\tege^ff;\!v, 'Contractile vacuoie.00" protoplasm, containing the nucleus
and contractile vacuoles (Fig. 1).
The first movements in the free state are amoeboid, but an
elongated shape is soon assumed ; and a flagellum, protruded ten-
tatively at first, becomes established at one end. The organism
THE MYCETOZOA
which thus enters the swarm -cell or zoospore stage swims free
in the water with a peculiar dancing movement produced by the
lashing of the flagellum. In this movement it rotates about its own
axis, and also moves as though over the surface of a cone, the apex of
which is situated at the posterior end of the zoospore (de Bary).
It is of an elongated pyriform shape, the narrow (" anterior ") end
being continued into the flagellum, which is about half to two-
thirds the length of the body. The thicker (" posterior ") end may
be evenly rounded, and is then curled somewhat to the side, but
is often extended in short pointed pseudopodia (Fig. 2, «). The
protoplasm of the anterior part is hyaline, and a layer of hyaline
protoplasm invests the rest of the body, the interior of which is
granular. The nucleus, with its contained nucleolus, lies in front,
At the base of the flagellum, and the contractile vacuole at the
posterior end. Non-contractile vacuoles (some of which at least
may be food- vacuoles) are also present in the granular protoplasm.
The particles of the latter exhibit a change of position within the
body, which in the large swarm-cells of Amaurocliaete atra recalls the
streaming movement characteristic of the plasmodia of the later stage.
Instead of swimming free, the swarm -cells may temporarily
assume an attached creeping mode of progression, in which the
body is elongated, and the flagellum, ex-
tended in front, turns from side to side
with movements which appear to be ex-
ploratory in purpose. Sometimes the body
is contracted and sends out pseudopodia
from all parts of the periphery (Fig. 4, c).
Bacteria abound in the wet places among
decaying vegetable matter, in which the
spores hatch. These are captured by the
zoospores by means of the pseudopodia ex-
tended from their posterior ends and drawn
into the body, where they are digested in
vacuoles (Fig. 2) (15). De Bary, to whom
this mode of obtaining food by the zoospores
was unknown, states (8, p. 452) that their
nourishment is exclusively saprophytic at
this stage.
it may be
appears very probable that it is both holozoic and saprophytic.
The swarm -cells multiply by division. In this process the
flagellum is withdrawn, the contractile vacuole disappears, and the
body assumes a rounded form. The nucleus, passing to the centre,
divides by karyokinesis (Fig. 3), and as the daughter nuclei resulting
from this division separate the protoplasm becomes constricted, and
-division occurs in a plane transverse to the axis of division of the
Zoospore of Stcmnnitis fusca,
showing successive stages in
the ingestion of a bacillus,
x 800. In «, it is captured by
one of the pseudopodia at the
hind end ; in c, it is enclosed
in a digestive vacnole. Another
bacillus is contained in an
(After A.
It is impossible to deny that Anterior vacuole.
. . J . Lister, 15.)
in part saprophytic, and it
THE MYCETOZOA
nucleus. A contractile vacuole has, meanwhile, appeared in each
daughter-cell, at a point remote from the plane of division, and
each develops a flagellum after separation is complete (15). It is-
probable that many generations of swarm-cells produced in this
manner succeed one another during this stage of the life-history.
When the zoospores are
treated by Heidenhain's hae-
matoxylin method, or with
picrocarmine, a reticulum comes
into view in the nucleus, and
the nucleolus takes a dark stain.
FIG. 3.
Three stages in the division of
zoospore of Keticvlaria lycoperdon.
x 1000. (After A. Lister, 17.)
FIG. 4.
Zoospores of Badhamia panicea,
stained, x 650.
The nucleus is sometimes round (Fig. 4, b), but more often it is
pyriform, being drawn out towards the base of the flagellum
(Fig. 4, a). The protoplasm intervening between the nucleus and
the flagellum is differentiated from the rest, and takes a darker
stain. It thus forms a more or less bell-shaped investment of the
former, the contour of which is most clearly seen in specimens-
which have assumed an amoeboid shape without retracting the
flagellum (Fig. 4, c).
Plenge (21) first called attention to this bell-shaped structure; and
Jahn (11), who has recently investigated it afresh, considers that it is-
part of the spindle formed in nuclear division when the zoospore divided^
and remaining in connection with the daughter nucleus. Jahn's figures
illustrating this point are very clear, but he does not explain how the
structure is formed in the zoospore prior to its first division.
In this and also in the succeeding stage a resting phase may
intervene between periods of activity. In it the flagellum and
pseudopodia are withdrawn, and the protoplasmic body rounding
itself into a sphere secretes a hyaline cyst-wall. These cysts are
known as microcysts. The formation of microcysts may be readily
induced by allowing a cultivation of swarm-cells to dry up, but
dryness is not a necessary condition for their production, for they
are formed in water, and some are present in almost every cultivation
of swarm-cells.
(b) The Amoebula.
After remaining for a period of uncertain duration in the stage
of their life-history in which the dominant form is that of the free'
THE MYCETOZOA
43
swimming flagellate zoospore, the flagellum is permanently with-
drawn and the organism passes into the amoeboid stage, which, as we
have seen, may be temporarily assumed daring the flagellate period.
They now creep about, adherent to other objects, emitting blunt
pseudopodia, and in this as in the preceding stage they may pass
into the condition of microcysts.
Each individual in the amoeboid phase of the life-history is the
lineal descendant, through the successive divisions of the flagellulate
phase, of a particular spore ; but from
the amoeboid phase onward the in-
dividuality is lost. This results from
the remarkable process, first seen by
Cienkowsld (7), of fusion of the
amoebulae to form plasmodia. The
amoebulae present in a particular area
draw together into groups, becoming
endowed, apparently, with the power
of mutual attraction, and the groups,
once formed, act as centres to which
neighbouring amoebulae, scattered
through the water, converge. After
coming in contact with one another
they remain at first visibly distinct,
but after a short time a complete
fusion of the protoplasm occurs. In this manner, the amoebulae
from all sides falling in and fusing in the common mass, the
plasmodia are produced.
(c) The Plasmodium.
The name plasmodium was first applied by Cienkowski in 1862
(6, p. 326) to the large expansions of protoplasm which form the
dominant phase of the life-history of the Euplasmodida. On his
subsequent discovery (7), in 1863, of their mode of origin by the
fusion of amoeboid swarm-cells, Cienkowski stated (p. 421) that such
a mode of origin must be included in the definition of a plasmodium.
The question arises whether, in this fusion of amoebulae to form
the plasmodia, we have a phenomenon comparable with the conjuga-
tion of the gametes of other forms, a view to which the mutual
attractiveness with which the amoebulae become endowed appears
to offer some support. If the analogy were complete, we should
expect that a fusion of nuclei would occur as well as a fusion of the
protoplasm of the amoebulae. But the evidence which we have at
present as to the behaviour of the nuclei lends no support to this
view. As many as eight amoebulae have been watched successively
fusing into a common mass, and their eight nuclei have been seen,
distinct, in the young plasmodium thus formed (18, p. 5). When
Fio. 5.
Amoebulae of Dulymium di/ormc
uniting to form a plasmodium. a,
separate amoebulae ; m, microcysts ;
pi, young plasmodium with ingested
bodies, x about 320. (After A. Lister,
18.)
44
THE MYCETOZOA
the number of fused amoebulae increases, direct observation of the
behaviour of the nuclei is, owing to their small size and the bulk
and movements of the protoplasm, increasingly difficult, and soon
becomes impossible.
Before describing the plasmodia in detail, it may be briefly
stated that they are masses of naked protoplasm of indefinite size,
containing numerous small nuclei. As de Bary discovered, they
are capable, under certain conditions, of passing into a passive
condition known as the Sclerotium, in which the protoplasm is
aggregated in cysts (Fig. 8), which together form a mass of horn-
like consistency. On the return of favourable conditions the
plasmodium resumes the active condition.
The mode of life of the plasmodium differs in different species,
FIG. 6.
Part of a plasmodium of Bailhamia ittriculans expanded over a slide, x S.
some (as in most of the Trichiaceae and Arcyriaceae) penetrating
the interstices of dead wood, others (as of most species of Craterium
and Didymium) living among heaps of decaying leaves, while one
species, Badlmmia utricularis, feeds on the surface of living fungi
which grow from the bark of dead trees.
The plasmodium expands over surrounding objects and moves
about, taking in nourishment. When exposed, it is seen by the
naked eye to be traversed by systems of vessel-like thickenings, the
main trunks of which divide and subdivide as they approach the
periphery, and are in free communication by the anastomosis of
their branches (Fig. 6).
The border of the plasmodium in the direction towards which
it is moving generally consists of a continuous film of protoplasm,
traversed by smaller branches of the system, but in the other parts
the film is generally not continuous, being interrupted in the inter-
THE MYCETOZOA 45
spaces between the thickenings. Hence in these regions the plas-
modium consists of a reticulum of anastomosing branches, extended
over the substratum. The arrangement of the branches closely
resembles that of the vessels traversing the mesentery of a mammal,
and, before their relation to the spore-bearing stage of the life-
history was known, the name Mesenterica was, in fact, given to
plasmodia of certain forms, under the supposition that they repre-
sented a new genus of fungi.
The form and degree of concentration of the plasmodium
vary widely according to circumstances. Sometimes it is
aggregated in a thick layer on the surface, as after emerging from
the interstices of a mass of rotten wood or tan, at other times it
is widely expanded in a thin layer of exquisite delicacy. Fries
relates hoAv the plasmodium of Diachaea elegans which he had
laid in his hat, while collecting, spread within an hour over a
great part of the latter in an elegant white network.
By suitable manipulation the plasmodia may readily be induced
to spread over glass cover-slips, and may thus be examined micro-
scopically.1 When thus seen the vessel-like thickenings are found
to be, in fact, streams of moving protoplasm. The flow may be
traced from the larger branches through the smaller into the
advancing border of the plasmodium, which becomes swollen and
more opaque as the streams pass into it. After a short time the
current is seen to slacken, then to stop, and shortly to begin again
in the reverse direction, the margin becoming thinner and more
transparent as the protoplasm leaves it. In a short time the flow
is again reversed, and again directed to the advancing border.
Thus a rhythmic flow, towards the margin and away from it, is
kept up through the plasmodium — the period in each case being,
in healthy conditions, about a minute and a half to two minutes,
though its duration is always longer in the direction in which the
plasmodium is moving than in the other.
The plasmodium is invested by a thin layer of homogeneous
hyaline and colourless protoplasm. Within this the protoplasm is
highly granular.
The hyaline layer is exceedingly thin over the greater part of
the periphery, but at the advancing border it is of considerable
breadth. The advance over the substratum occurs chiefly while
the flow in the veins is directed towards this border. Under
these circumstances the border becomes more and more turgid, and
1 An easy way of making microscopic preparations of living plasmodia is to lay
out a number of cover-slips on a plate, sprinkle them with rain-water, and then to
s., Uter small fragments of sclerotium over them. In a moist atmosphere the
encysted protoplasm resumes the active stage in the course of a few hours, and the
small plasmodia thus arising spread in delicate fan-like expansions over the glass.
The cover-slips may then be mounted over a hole in wet blotting-paper, on a slide, or
in some other manner, ensuring the maintenance of a moist atmosphere.
THE MYCETOZOA
small rounded lobes of hyaline substance are seen to start forward,
and then to become stationary, as though the surface tension had
momentarily been overcome by the pressure from within, and had
then been rapidly renewed. It is to be observed that the contents
of such a newly-formed lobe are at first not, as might have been
expected, the granular protoplasm which flows in the " veins," but
they are hyaline, the passage of the granules into the interior of
the lobe occurring subsequently.
The material in the " veins " appears to be of highly fluid
consistency, the granules moving over one another with great
*,^x>:^£-^:^^-:^:!:-''^ ' ''•'• . ''''", •'. .-:V>dr-:--:-f^
FIG. 7.
o, part of a stained plasmpdium of 5. utricularis. n, nuclei, x 110 ; b, nuclei, x 500. Some
.are in process of simple division, c, part of a plasmodium in which the nuclei are in simul-
taneous division by karyokinesis. <?-/, other stages in this mode of division, x 650.
freedom. When a small channel is watched it frequently occurs
that an ingested sclerotium cyst or other large object blocks a
narrow part, and the flow in the channel is temporarily checked.
If the object ultimately passes on, its passage is followed by a
gush of the protoplasm behind it, at increased velocity, the flow
gradually resuming its normal rate. When a vein traversing a
continuous portion of the plasmodial film is examined the flow is
seen to be rapid at the centre and slower at the sides.
The phenomena presented by the circulation in the veins suggest
the view that their contents are passively propelled, as the result of
the contraction of the more external part of the plasmodial substance.
THE MYCETOZOA 47
De Baiy concluded (2, pp. 43-51) that besides such a positive
vis a tergo, due to contraction of the protoplasm in the regions from
which the flow occurs, there is evidence of a negative pressure
exercised by the plasmodium in the regions towards which the flow
is going, and due to its expansion from the previous state of
contraction.
While the conclusion appears probable that the streaming
movement is due, in part at any rate, to the contraction of the
outer portions of the protoplasm, we may bear in mind that such
an explanation appears inapplicable to other phenomena, which we
should expect to belong to the same category, such as those
exhibited by the pseudopodia of the Foraminifera, in which
streams of granules course along a filament of extreme tenuity in
opposite directions.
When a piece of sclerotium resumes activity on being wetted,
it sends out a fan- like expansion over the substratum, and the
rhythmic flow is seen to be alternately away from the central mass
and back to it ; but as the fans extend farther over the substratum,
the flow in the several parts of the plasmodium becomes less and
less co-ordinated, in proportion as they separate from one another.
The several parts separate into distinct plasmodia, and distinct
plasmodia fuse with complete freedom.
Reaction of Plasmodia to External Conditions. — Experiments testing
the reaction of plasmodia to variations in external conditions have
led to some positive results, an interesting account of which is
given by Stahl (22).
During the vegetative period of their existence plasmodia move
from the drier to the moister parts of their substratum, though at
the approach of the spore-producing stage the movement is in the
opposite direction, the organism seeking the driest part of its en-
vironment whereon to undergo its change into spores. Connected
apparently with the favourable influence of a moist atmosphere is
the phenomenon, familiar to tanners, of the " flowering of the tan-
heaps " at the approach of wet weather. This consists of the
emergence at the surface of the bright yello.w plasmodia of Fuligo
septica, commonly known as Flowers of Tan, which abound in the
heaps, and, except under such conditions (and at the approach of
sporulation), inhabit the deeper parts of the heap.
When water is allowed to flow through the substratum,
plasmodia move in a direction opposite to the current, a tendency
which may be utilised for the purpose of isolating them for
experimental purposes. By arranging strips of filter paper, through
which water is flowing, so that their lower ends rest on the mass
containing the plasmodia, the latter will crawl up the filter paper,
and may thence be transferred, in the same manner, to glass slides.
48 THE MYCETOZOA
The presence of substances suitable for food exercises a strong
attraction on plasmodia. When the spreading border touches
such a substance the streaming movement is at once quickened in
this direction, and the outlying lobes being drawn in, the whole
plasmodium is rapidly concentrated on the nutrient material (14).
The contrary effect is seen when harmful substances are brought
into their neighbourhood.
The plasmodia of many species are said to shun the light, but
this is not the case with all ; that of Badhamia utricularis, for
example, will, if a moist atmosphere be maintained, continue to
spread over the pilei of the fungi on which it feeds, though these
may be exposed to full sunlight.
Nuclei. — The plasmodia are multinucleate from their origin;
but from the fact that a minute plasmodium a few millimetres in
diameter will grow, when supplied with food, till it is many inches
in diameter, and that the nuclei are then as numerous, in a small
sample, as they were before the growth had occurred, it is clear
that the nuclei increase in number pari passu with the growth of
the protoplasm. There is reason to believe that this increase occurs
in two ways, (a) A simultaneous division of the nuclei by karyo-
kinesis has been found to be in progress when plasmodia (of Badhamia
utricularis, Fig. 7, c-f) are stained (17, p. 541) — a process comparable
apparently with the simultaneous division of nuclei which occurs in
the vegetative stage of Actinosphaerium. (b) Multiplication by simple
division is not easy to establish, where, as in this case, prolonged
observation of the nuclei in the living state is rendered difficult by
the movement of the plasmodia, but the following observation appears
to show that it is of frequent occurrence in their groAvth : —
A plasmodium of Badhamia utricularis, spreading and feeding on
the pilei of the fungus Auriculuria, increased in size about fourfold
in fourteen hours; and during this time a small portion of it was
removed, smeared on a cover-slip, and fixed every quarter of an hour.
On staining the 56 samples so obtained, the nuclei were found to be
approximately equally abundant in all, and presented considerable
differences in size, but in no case was there any indication of karyo-
kinetic division. Now in the karyokinetic division of nuclei which
occurs prior to spore-formation (see p. 52) the process lasts from one
to one and a half hours. Assuming the same duration for the
karyokinetic division of the nuclei in the growing plasmodium, and
bearing in mind that the division in this manner, when observed,
was simultaneous, we must conclude that it had not occurred in
the fourteen hours during which the observations were made ; yet
from these observations it appears that in this period the number
of the nuclei had increased about fourfold (18, p. 9). As a fact,
the appearance of the nuclei in various phases of constriction is of
common occurrence when stained plasmodia are examined with a
THE MYCETOZOA 49
high power (Fig. 7, b), but the appearance is so similar to that of
overlapping nuclei, that without the confirmation afforded by the
experiment above described, the conclusion, that in addition to a
periodic (?) increase by mitosis, the nuclei multiply by simple
division, could hardly have been accepted as secure.
With regard to the distribution of the nuclei, it is to be observed
in stained preparations, in which the plasmodium has been suddenly
killed, that they appear to be as numerous in proportion to the bulk
of the protoplasm in the veins as they are in the film of the plas-
modium on either side of them.
In size the nuclei vary from 2 '5 to 5 /x. In the resting condi-
tion they present a well-marked reticulation and a distinct nucleolus.
In mitosis a well-marked spindle is formed, and the chromosomes
are rounded and compact. In number the latter appear to be
about 8 or 9, in Trichia (see, however, p. 65). It may be noted
that as in other Protozoa the nuclear membrane is maintained
until after the separation of the chromosomes to form the daughter
nuclei.
Contractile Vacuoles abound in the peripheral layer of the plas-
modium, and may be readily seen in the expansions between the
channels. They are generally about 7-8 p in diameter.
The protoplasm contains abundant granules, of minute size,
the nature of which has not been ascertained. In one group of
Mycetozoa, the Calcarineae, granules of carbonate of lime abound
in the plasmodia. They are not present in other species, and their
relation to physiological processes is obscure.
The plasmodia of many species are white, but those of others
are yellow, pink, purple, or green, and owe their colour to a fluid
pigment scattered in small drops through the protoplasm. In the
Calcarineae, the fluid pigment invests the granules of lime.
The Food of Plasmodia. — The plastnodia of the great majority of
the Mycetozoa feed on the decaying vegetable matter among which
they live. Their mode of nutrition must be regarded as both
saprophytic and holozoic, for they are able to absorb nutrient
matters in solution (cf. Stahl, 22) as well as to engulf their food.
Those living among leaves and under bark are found charged with
particles which have been ingested, and the undigested portions
are found strewn along the track they have traversed. Badhamia
utricularis is exceptional in feeding on living fungi (Stereum, Auri-
cularia, etc.), though it will also live and thrive on the same fungi
after they have become dried, if they are wetted again with water.
Experiments have shown that proteids (coagulated albumen,
sclerotium cysts), taken in by plasmodia, are digested in vacuoles
into which an acid is secreted by the surrounding protoplasm (see
the experiments by Miss Greenwood and Miss Saunders, 10),
50 THE MYCETOZOA
although the reaction of the plasmodium as a whole is alkaline
(Metschnikoff, 19). Pepsine, the presence of which in plasmodia of
Fuligo was shown by Krukenberg (12), is doubtless the agent by
which, acting in this acid medium, the digestion is brought about.
Raw starch grains which had been ingested were found to pass
unaltered through the plasmodium of Badhamia utricularis, though
grains which had been previously swollen in warm water were
digested (14).
The plasmodium of this species at any rate has the power of
dissolving cellulose. This is evident from the nature of its food,
and has also been directly observed (14) when a plasmodium was
seen to extend over the hyphae of a mould. The cellular walls of
the hyphae were dissolved " like sugar in hot water " as soon as the
hyaline border of the plasmodium reached them.
The Sclerotium Condition. — As in the earlier phases of the life-
history, a passive condition may, as we have seen, be assumed in
the plasmodium stage, the protoplasmic mass breaking up into
cysts and assuming as a whole a firm consistence. To this con-
dition de Bary gave the name Sclerotium. As it supervenes,
the streaming movements gradually cease, foreign bodies are
extruded, and the plasmodium becomes separated into distinct
masses, each of which contains 10-20
nuclei, and secretes a membranous cyst-
wall.
The assumption of the sclerotium
condition is readily induced by allowing
plasmodia to dry, and when so treated
they assume a firmer and firmer con-
sistency, until the masses of cysts attain
a hard and horn-like condition, in which
Part of a section of the plas- . •
medium of Sadkamia utricularis vitality may be preserved for as many
when passing into the sclerotium ,-, c, •, , •
condition, x 310. «, a nucleus, as three years. Sclerotium cysts may,
however, be formed in water, but the
conditions under which this occurs are obscure. When the dry
sclerotia are placed in water the protoplasmic masses absorb or
break through the cyst-walls, fuse together, and the active plas-
modial condition is resumed. The revival occurs in a few hours.
It is to be noted that the unit represented by the sclerotial
cyst is different from the microcyst of the preceding stages, which
was uninucleate, and also from the sporangium of the succeeding
stage, which is much larger, and contains a much greater number of
nuclei.
(d) The Formation of Sporangia.
The conditions under which plasmodia pass into the succeed-
ing phase, that of spore-production, are in part obscure, but one
THE MYCETOZOA
element in this result is the absence of further nourishment. In a
cultivation of Badhamiu utricularis, after the plasmodium has been
supplied with abundant food, arid has increased largely in bulk, the
formation of sporangia may generally be induced by withholding
the supply of fungus, which is the food material of this species.
If while food is withheld a suitable substratum, such as clean
sticks, is supplied, the plasmodium will generally creep on the
sticks and there form into sporangia.
The mode of formation of the sporangia in this species may
be described as characteristic of the majority of Mycetozoa, the
principal departures from the type being subsequently noticed.
As seen by the naked eye, the plasmodium previously extended
in a diffused network over the substratum is seen to become
aggregated in lobed masses 0*5 to 1 mm. in diameter, which in this
species are grouped closely together, and vary in number from a
few to many thousands, in proportion to the size of the plasmodium.
These are at first connected by the veins of the plasmodium, and
may be seen to expand and contract in accordance with the
direction of the streaming movement, which is still maintained.
Gradually, however, the veins connecting them diminish, and soon
the whole protoplasm is completely segregated into distinct lobes,
or young sporangia.
While the formation of the sporangia is in progress, all re-
maining foreign bodies which have been
ingested with food in the plasmodial
stage are expelled, and a secretion takes
place of a structureless, transparent sub-
stance which serves for the support
and enclosure of the spores. At the
surface of each of the lobed masses,
constituting the young sporangia, is
thus formed a sporangium wall, which
in the mature state is a thin wrinkled
membrane, completely investing it. At
the constricted base of the sporangium
this is continued to the substratum as a
slender stalk of varying length (Fig. 9).
While the sporangium wall is
secreted on the surface of the spor-
angium, a similar process occurs along
certain tracts throughout the interior, a, a group of sporangia of Badhamia
aivino- risp /in tnia cnpr>if>cA fn an -mocrn utricularis. X 12. b, a cluster of
giving rise (in tniS Species; to an anaSCO- spores ; c> a single spore ;d, part of the
mosing network of flat bands with capillitium containing lime granules.
, ° . . b and d x 170. (After A. Lister, 18.)
broad, thin expansions at the points ot
junction (d). From a superficial resemblance to a structure in
•Gasteromycetous Fungi, this network traversing the interior of
THE MYCETOZOA
the sporangium is known as the capillitium. At the periphery it is
continuous with the sporangium wall.
The lime granules, which existed free in the plasmodium, pass
out of the protoplasm simultaneously with this secretion. Some
are sparsely scattered through the sporangium wall, but the
majority are closely packed in the strands of the capillitium, which
are white and brittle in consequence (Figs. 9, d, and 10).
Until the secretion of sporangium wall and capillitium is
complete the protoplasm remains a homogeneous mass, with
multitudes of nuclei scattered through it. Their completion is
followed by a division of the nuclei by karyokinesis, which occurs
Fio. 10.
20. To the left are three sporangia, the walls of which
H naniiijtium. Three to the right are unopened ; above
of the capillitium.
simultaneously throughout the sporangium and occupies from one
to one and a half hours (Fig. II).1 While this is in progress the
protoplasm breaks up into rounded masses which contain some 6-10
nuclei, but they subsequently divide into masses, each containing
one of the dividing nuclei ; and as the nuclear division is completed
and the daughter nuclei draw apart, a further division of the
protoplasm occurs, and each nucleus then occupies a single mass
of protoplasm (Fig. 12). These masses are the young spores.
They soon secrete a spore-wall which is of a violet-brown colour^
1 This was first observed by Strasburger (23) in Trichia fallax. The observation
has been repeated by my father in two other species of Trichia, and in representatives
of the genera C'omatricha, Physarum, and Badhamia (17), and, since that paper was-
published, in Reticularia and Arcyria.
THE MYCETOZOA
53
and covered with minute spines or tubercles. The spores are ap-
proximately spherical, and 9 to 12 yu. in diameter. In several species
the spore -wall has been found to
give the reaction of cellulose.
Fio. 11.
Tart of a section through a young
sporangium of Trichia varia, showing
the division of the nuclei prior to
spore - formation. x 650. c, capil-
litium thread ; n, a nucleus. In
several cases the axis of the dividing
nucleus is directed towards us, and
the karyokinetic figure is therefore
not displayed.
Part of a section through a spor-
angium of Trichia raria after the
spores are formed. Capillitium
threads are seen in longitudinal and
transverse section, x 650.
The ripe sporangium thus consists of a mass of spores,
enveloped by the sporangium wall and traversed by a supporting
reticulate capillitium, which, like the wall, has a dry membranous
character, though charged throughout with white granules of lime.
As ripening proceeds the sporangium wall becomes more and more
friable, until it breaks and the spores are spread abroad on the
lightest currents of air.
Considerable variations of structure are presented by the
sporangia of the Mycetozoa. The stalk may be absent altogether,
the sporangia being sessile on the substratum (Fig. 13, e). When
present it is usually solid, but may be hollow, and sometimes, as in
Trichia fallax, may contain cellular elements, which appear to be
aborted spores.
In many species the stalk is continued in the interior of the
sporangium as a structure known as the columella, which may reach
to the apex or terminate short of it. A columella may, however,
be present in sessile sporangia, as in species of Chondrioderma
(Fig. 13, e}.
Stalked sporangia are, at their first formation, sessile, and in
the majority of cases the stalk may be regarded as the basal part
of the sporangium wall, which has shrunk and fallen in about the
base of the sporangium, as the latter has risen above the substratum
(Figs. 13, a, and 15, a) ; but in the Stemonitaceae the stalk, with its
54
THE MYCETOZOA
continuation, the columella, is, as de Bary showed, an axial structure
secreted in the interior of the young sporangium (Fig. 14, a-e). In
the formation of these sporangia the basal portion of the stalk is
formed first and additions are made to the apex as the protoplasm
climbs Up this axial support. In Stemonitis fusca and splendens the
stalked sporangia may attain a height of 20 mm.
In addition to the skeletal or supporting structures of the spore-
bearing stage above mentioned, another is present in many genera —
the hypothallus. This consists of a network of strands or a con-
tinuous film, formed of the same material as the other supporting
structures, extended over the substratum, and forming the base
on which the sporangia are inserted (cf. Fig. 13, d). Its presence
apparently depends on the occurrence of the secretion, in the later
FIG. 13.
a, sporangia of Physarum nutans, Pers., x 15. 6, piece of sporangium wall, with groups of
lime granules, capillitium threads, with lime-knots (k) and spores of Physancm, nutans, x 210.
c, spore of same, x 450. d, sporangia of Craterium pedunculatum, Trent, each with a discoidal
hypothallus at the base of the stalk, x 17. e, sporangia of Chondriodermu tcstaceum, Host.,
showing the double sporangium wall (outer layer with lime, inner membranous), and in the
upper sporangium the columella, x 15. /, threads of the capillitium of the same, x 280. g,
group of crystals of lime from the wall of Spumaria alba, x 210. h, a crystalline disc from
the sporangium wall of Lepidoderma tigrinuam, Rest., x 210. (After A. Lister, 18.)
stages of the plasmodial condition, of the substance which dries into
the supporting material — its reticular or continuous character corre-
sponding with the state of diffusion of the plasmodium during its
formation.
The sporangium wall may consist of two layers as in Chondrioderma
(Fig. 13, e), where the outer is densely charged with lime granules,
and the inner is membranous and free from lime. In some species
of Craterium (Fig. 13, d) the upper portion of the sporangium wall
forms a lid, which readily falls away, exposing the contents. In
Didydium (Fig. 14,/) and Cribraria the wall of the mature sporangium
is represented wholly or in part by an open network, through the
THE MYCETOZOA
55
meshes of which the ripe spores escape ; and in Comatricha it is
evanescent, and disappears soon after the sporangia are ripe.
The capillitium also presents great variation. In the genera form-
ing the Calcarineae the lime may be uniformly distributed through
it (Badhamia, Figs. 9 and 10) or collected into lumps ("lime-knots")
at the points of junction of the reticulum (Physarum, Fig. 13, b,
Fuligo, Craterium). In Chondrioderma (Fig. 13, e and /), Didymium,
and others the lime is only laid down in or on the sporangium wall
and the capillitium is free from it. The strands of the capillitium
are generally, though not invariably, continuous at the periphery
with the sporangium wall, and internally with the columella, if this
structure is present.
FIG. 14.
a, four sporangia of Stcmonitis splendens, Rost.; that to the right is represented free from
spores and shows the columella extending nearly to the top ; x 2. b, part of an empty
sporangium of S. splendens, showing the columella (c) and a branch springing from it and
dividing to form the surface network of the capillitium. To the right a group of spores, d, e,
stages in the development of the sporangia of Stemonitis ferruginea, Ehrenb., showing the
development of the columella in the axis of the young sporangium. The space between the
columella and the protoplasm is artificial. /, empty sporangium of Dictydium umbilicatum,
Schrad., x 30. (d and e after de Bary, 2 ; the other figures after A. Lister, 18.)
The capillitium attains its most elaborate development in the
Arcyriaceae and Trichiaceae (Fig. 15). In the former it consists of
an elastic network, attached or not to the base of the sporangium,
but free from its sides, and with the strands beset with spines or
transverse thickenings, resembling cogs on a wheel (Fig. 15, /). At
maturity the evanescent film of the sporangium wall gives way and
the capillitium expands into a long loose tangle, scattering the spores.
In the Trichiaceae the threads of the capillitium have spiral
thickenings. In Hemitrickia the threads are united into a network,
as in Arcyria, but in Trichia they are usually unbranched and lie
free among the spores (Figs. 11, 12, and 15, b). Owing to their
spiral sculpture they twist and untwist with varying changes of
moisture, and thus subserve the distribution of the spores.
In a large section of genera, the Anemineae, a capillitium is
absent.
THE MYCETOZOA
In the Physaraceae the lime is aggregated in the sporangium in
the form of granules ; but in the Didymiaceae, though, as in other
Calcarineae, granular in the plasmodium stage, it assumes, when
separating from the maturing sporangium, a crystalline form, being
deposited on the sporangium wall either in clusters of crystals
(Didymium and Spumaria, Fig. 13, g) or in discs with a radiating
arrangement (Lepidoderma, Fig. 13, /t). It is clear that in this
process the lime must be in a state of solution as it passes through
the sporangium walls.
The spores vary in diameter from 3-5 yu, (in Tubulina stipitata) to
16-20 /x (in Licea pusilla) ; and the size is generally approximately
uniform in each species. The surface may be smooth, tuberculated,
G
o
FIG. 15.
a, sporangia of Trichia varia, x 15 ; 6, one of the capillitium threads ; c, spores, x 160 ; <?,
a spore of Hcmitrichia chrysospora, x nearly 600 ; c, sporangia of Arcyria incarnata ; in one the
sporangium wall lias broken and the capillitium has expanded, in another the empty base
alone remains, x 16 ; / and g, capillitium and spores of A. punicea, x 160. (a, d, and e, after
A. Lister, 18.)
or reticulated (Fig. 15, d) ; and the sculpture may be absent from
one side of a spore, a peculiarity generally associated with the
arrangement of the spores in clusters.
Aethalia and Plasmodwcarps. — In several species of Mycetozoa
the sporangia, instead of standing apart, are more or less closely
fused to form large compound bodies known as Aethalia, which
present characteristic features of shape and structure. The identity
of the individual sporangia may remain obvious or be entirely lost
in the mature aethalia, but in the course of their development their
compound nature is usually evident.
In many cases (Fuligo, Fig. 16, Iteticularia, Lycogala) the proto-
plasm Avithdraws from the peripheral portions of the sporangia, the
walls of which collapse in consequence and together form a cortical
layer, and a similar withdrawal of protoplasm from the basal
THE MYCETOZOA
57
region often gives rise to a spongy base to the aethalium, to
which the name hypothallus has been loosely applied, though the
structure is as distinct from the true hypothallus as is any other
part of the supporting substance.
Many Mycetozoa forming aethalia are closely allied to species
with discrete sporangia. Thus Fuligo is an aethalioid form of
Fio. 16.
Aethalium of Fuligo septica. a, part of a ripe aethalium in section, showing the cortical
layer, x 1. b, part of a section of the developing aethalium, showing the separate convoluted
tubular sporangia_of which the aethalium is composed, x about 390. (After de Bary, 2.)
Physarum, Spumaria of Didymium; and species in which the
sporangia are usually distinct may assume an aethalioid form, as in
the " confluent " variety of Stemonitis fusca.
In some species the plasmodium does not become rounded off into
distinct and symmetrical spor-
angia in the spore-producing
stage, but retains a diffused
.and lobate form. In other re-
spects maturation proceeds as
in ordinary sporangia. These
bodies are known as plas-
modiocarps (Fig. 17). Aethalia
appear to be formed by the
fusion of sporangia, while
plasmodiocarps are sporangia
incompletely segregated.
Plasmodiocarps are characteristic of some genera (Licea), but
frequently occur together with completely -formed sporangia in
the same species of others.
THE EXOSPOREAE.
The genus Ceratiomyxa (formerly known as Ceratium), the single
representative of the Exosporeae, differs from the Endosporeae
Fio. 17.
The plasmodiocarp form of Diili/minm rffusum.
x 15. (After A. Lister, 18.)
THE MYCETOZOA
in the relation of the spores to the supporting structures, and
in the changes which occur
when the spores are hatched
(Fig. 18).
The plasmodium inhabits
rotten wood and emerges in
cushion-like masses, which may
become honeycombed with de-
pressions or separate into dis-
tinct antler-like branches. On
its emergence it assumes the
condition of an intimately
anastomosing network of pro-
toplasmic strands distributed
through an abundant hyaline
gelatinous substance, and at
first exhibiting the characteristic
rhythmic ebb and flow seen in
the plasmodium of the Endo-
sporeae. As the definitive
shape is assumed, the proto-
plasm leaves the interior and
accumulates at the surface of
the mass, at first as a close-
set reticulum, and then as a continuous layer investing the
gelatinous substance, though with a thin covering of the latter still
external to it. The layer of protoplasm then separates into a-
mosaic of polygonal cells (Fig. 18, b), each occupied by one of the
nuclei of the plasmodium. The cells are at first in contact with
their fellows at their margins, but they now draw apart, and each
projects in the centre of the area which it occupied, beyond the
contour of the lobe on which it lies, though still covered by the
thin hyaline layer. As the projection increases its base becomes-
constricted, and finally the cell, or young spore, containing the
nucleus and all the protoplasm which occupied the polygonal area,
is raised some distance above the general surface, invested by
a thin covering, and supported on a slender stalk — both furnished
by the investing layer. Each spore now assumes an elliptical
shape, secretes a firm colourless wall, and is ready to drop away.1
During the later stages of this process the gelatinous material'
constituting the sporophore dries, and by the time the spores are
ripe, forms a shrivelled, white mass of extreme tenuity (Fig. 18, a).
According to Famintzin and Woronin (9), who first described the
details of the life-history of Ceratiomyxa, the protoplasm emerges in
the morning and the spores are ripe within twenty-four hours.
1 For nuclear changes during spore-formation, cp. p. 66.
FIG. 18.
Ceratiomyxa mucida, Schroet. a, ripe
sporophore, x 40 ; 6, maturing sporo-
phore, showing the development of the
spores, x about 100 ; c, ripe spore ; d,
hatching spore ; e-h, stages in the develop-
ment of the zoospores, x 800. (a and c-h
after A. Lister, 18 ; 6, after Famintzin and
Woronin, 9.)
THE MYCETOZOA 59
The spores, which at their formation are uninucleate (Fig. 1 8, c),
are found, on hatching, to contain four bodies which are apparently
nuclei (Fig. 18, d\ so it would appear that division of the nucleus
occurs in the spore stage. When the spores are brought into
water the contents emerges, becomes amoeboid, and successively
constricted into separate lobes, two, four, and eight in number
(Fig. 18, e-g). At the stage when eight lobes are formed each
develops a flagellum (Fig. 18, h), and finally, becoming distinct
from its fellows, swims off as a zoospore. It is evident that a
further division of the nuclei must occur during this process. The
zoospore subsequently enters the amoeboid stage, and the amoebae
probably fuse to form plasmodia, as in the Endosporeae, though the
process has not been followed in Ceratiomyxa.
On comparing the somewhat incomplete details of this life-
history with those of the Endosporeae, it seems clear that the
abundant gelatinous substance in which the protoplasm is contained
at the end of the plasmodium stage of Ceratiomyxa is, as Famintzin
and Woronin pointed out, comparable Avith the secreted material
which is converted into the supporting structures of the
Endosporeae. In Ceratiomyxa the spores, instead of lying in a
compact mass, contained in a sporangium, are distributed in a
superficial layer, and the sporophore is accordingly disposed so as
to offer an extensive surface for their support.
The division of nuclei prior to spore-formation, found wherever
the development has been followed in the Endosporeae, has not been
seen in Ceratiomyxa, and as this process is frequently met with in
other groups of Protozoa, its apparent absence here is remarkable.
It is possible that this division is represented by the first of the
nuclear divisions occurring within the spore ; in which case the
spores of Ceratiomyxa would be comparable with the masses into
which in the Endosporeae the protoplasm separates about the
dividing nuclei before spore-formation, rather than with the spores
of that group. If this comparison were established, however, the
two following divisions which occur in Ceratiomyxa before the
zoospores are formed would remain features peculiar to the genus.1
THE SOEOPHORA.
The other group here included with the Mycetozoa, the
Sorophora, consists of forms the alliance of which with the
Euplasmodida is somewhat remote. They live in decaying vege-
tables and the dung of herbivorous animals. There is no flagel-
late stage in the life-history, and it is in the form of amoebulae
that the active phase, with growth and reproduction by fission,
occurs. At the end of this vegetative phase, and only as a pre-
1 Cf. the Postscript at the end of this article.
6o
THE MYCETOZOA
liminary step to sporulation, the amoebulae draw towards their
fellows in groups, which may be composed of many hundreds of
units, but they maintain their individual distinctness and do not
fuse to form a true plasmodium as in the Euplasmodida. Spore-
production occurs in air, at the surface of the substance in which
the vegetative phase has been spent.
In Guttulina, as well as in the members of the Dictyosteliaceae, a
remarkable differentiation occurs among the amoebulae forming the
pseudoplasmodium, comparable with that characteristic of the
organisation of the Metazoa.
Some of the amoebulae secrete a
firm membrane and become joined
end to end to form a stalk (Fig.
1 9, c and d), attached below to the
substratum, and up this the other
amoebulae climb and pass into the
encysted condition at the top as
a naked cluster of spores. In
Didyostelium the stalk is long and
simple ; in Folysphondylium it is
branched (Fig. 19, d).
Tlie supporting structures of
the Sorophora are evidently of a
different nature from those of the
Euplasmodida, in which they are
not cellular, but formed as secre-
tions of the protoplasm.
It is, of course, possible that
the pseudoplasmodia of the Soro-
phora may represent a stage in
the evolution of the true plas-
modium, which in the other group
is such an important phase of the
life -cycle; but it appears more
probable that both Euplasmodida
and the Sorophora are to be
derived from some simple forms
with a life-history resembling that
of Protomonas or Bursulla among
the Proteomyxa.
Fio. 19.
a and 6, Copromyxa protea, Fayod. a, a
simple, b, a branched form of sorus, slightly
magnified (after Fayod. )• c and d, Poly-
sphondylium violaceurn, Brefeld. c, a young
sorus, seen in optical section, with a mass
of amoebae grouped round the stalk, and
others still extended about the base, x 110.
d, a sorus approaching maturity. The stalk
has become compound. The lowest whorl
of secondary sori is complete, those above it
are in varying degrees of completeness, x 20.
(After Brefeld. From Zopf, 24.)
Two hundred and sixty -five
species of the Euplasmodida are
described in the British Museum Catalogue (18); Zopf (24)
enumerated nine species of Sorophora, and Olive (20), more
recently, twenty.
THE MYCETOZOA 61
The classificatory characters are mainly derived from the
sporangia, the capillitium (when it is present), and the spores.
Some species stand apart from their allies with great distinctness,
but in many genera examples intermediate in character between
the species are of common occurrence, and it is only by large
experience of the frequency with which the forms, as they occur
in nature, group themselves about certain centres that a correct
idea of the species can be attained.
The distribution of most species appears to be, so far as it has
yet been determined, world-wide in the more humid parts of the
temperate and tropical regions of the globe, where woodlands and
forests offer conditions favourable to their existence — a fact which
is doubtless dependent on the ease with which the minute spores
are carried in currents of air.
No Mycetozoa have hitherto been met with in a fossil state,
though from the degree of differentiation of the sporangia we cannot
doubt that the group is of high antiquity, and has in past time, as
at the present, played an important part in the disintegration of
vegetable tissues.
It is remarkable that no parasitic organisms are known to live
on Mycetozoa, a fact which Stahl attributes to the readiness with
which foreign bodies are cast out by the organisms in the plas-
modial stage.
In writing this account of the Mycetozoa constant reference has
been made to de Bary's classical work (1-3), to the papers of
Cienkowski (5-8), and to Zopf's treatise (24). But I wish especially
to acknowledge my obligations to the work of my father, Mr. A.
Lister, on their life -history and classification. So far as I have
been able to speak of the biological aspects of the group from my
own knowledge, it is mainly to the opportunities I have had in
following this work that I am indebted. The proof-sheets of this
article have been submitted to my father, and I feel that its-
authority is greatly enhanced when I add, as he allows me to dor
that the conclusions are in the main in accordance with his views.
SUB- CLASS I. EUPLASMODIDA.
The contents of the spores develop, on hatching, into flagellate
zoospores. Amoebulae completely fused to form the plasmodium, which
is the dominant phase of the vegetative period.
DIVISION I. ENDOSPOREAE.
Spores developed within sporangia.
COHORT I. AMAUROSPORALES.
Spores violet, or violet-brown.
62 THE MYCETOZOA
SUB-COHORT A. CALCARINEAE.
Sporangia provided with lime.
ORDER 1. Physaraceae.
Lime in minute, round granules.
A. Capillitium a coarse network charged with lime throughout.
Genus — Badliamia, Berk. (Figs. 9 and 10).
B. Capillitium a delicate network of threads with vesicular
expansions tilled with lime-granules ( = lime-knots), a. Sporangia com-
bined into a convolute aethalium. Genus — Fuliyo, Haller (Fig. 16).
P. Sporangia single, scattered, or aggregated, a, sporangium wall
membranous. Genera — Physarum, Pers. (Fig. 13, a). Sporangia sub-
globose or in the form of plasinodiocarps. Physarella, Peck. Sporangia
tubular. 6, sporangium wall cartilaginous throughout, or at the base
only. Genera — Cienkowskia, Rost. Sporangia in the form of plasmodio-
carps ; Capillitium with free hooked branches. Craterium, Trent (Fig.
13, d). Sporangia goblet - shaped or subglobose. Leocarpus, Link.
Sporangia ovoid, glossy.
G. Capillitium without lime -knots. Genera — Chondrioderma, Rost.
(Fig. 13, e). Sporangium wall of two layers, more or less combined.
Trichamphora, Jungh. Sporangium wall of one layer, fragile ; sporangia
saucer-shaped.
D. Lime confined to the stalk and columella ; sporangium wall
membranous. Genus — Diachaea, Fries.
ORDER 2. Didymiaceae.
Lime deposited in the form of crystals or crystalline discs on the
outer surface of the sporangium wall ; Capillitium without lime-knots.
Genera — Didymium, Schrader (Fig. 17). Lime in crystals ; sporangia
simple. Spumaria, Pers. (Fig. 13, </). Lime in crystals ; sporangia united
into an aethalium. Lepidoderma, de Bary. Lime in crystalline discs
(Fig. 13, h) • sporangia simple.
SUB-COHORT B. AMAUROCHAETINEAE.
Sporangia without deposits of lime ; Capillitium dark brown or violet
brown.
ORDER 1. Stemonitaceae.
Sporangia stalked, the stalk extending within the sporangium as a
columella ; sporangium wall a single delicate membrane, often evanescent.
Genera — Stemonitis, Gleditsch (Fig. 1 4, a-e). Sporangium wall evanescent ;
.Capillitium springing from all parts of the elongated columella, its ultimate
branches forming a superficial net. Comatricha, Preuss. Like Stemonitis,
but the branches of the Capillitium not forming a superficial net. Ener-
thenema, Bowman. Sporangium wall evanescent ; columella reaching to
the apex of the sporangium, where it forms a superficial expansion from
which the capillitium springs. Lamproderma, Rost. Sporangium wall
somewhat persistent, columella about half the height of the sporangium.
THE MYCETOZOA 63
Clastoderma, Blytt. Sporangium wall partly evanescent, persisting in the
form of minute discs, at the tips of the rigid capillitium threads ; columella
ehort or none. Echinostelium, de By. A minute colourless form with
long stalks and a sparsely-branched spiny capillitium.
ORDER 2. Amaurochaetaceae.
Sporangia combined into an aethalium ; capillitium of irregular
strands and threads, or complex. Genera — Amaurochaete, Rost. Capil-
litium of irregular branching threads. Brefeldia, Rost. Capillitium of
horizontal threads, with many-chambered vesicles.
COHORT II. LAMPROSPORALES.
Spores variously coloured, never violet.
SUB-COHORT A. ANEMINEAE.
Capillitium absent, or not forming a system of uniform threads except
in Alwisia.
ORDER 1. Heterodermaceae.
Sporangium wall membranous, beset with minute round granules,
and (except in Lindbladia) forming a net in the upper part. Genera —
Lindbladia, Fries. Sporangia sessile, compacted or aethalioid, the wall
not forming a net in the upper part. Cribraria-, Pers. Sporangia stalked ;
sporangium wall with thickenings in the form of a delicate persistent
net, expanded at the nodes. Dictydium, Sclirader (Fig. 14,/). Sporangia
stalked ; sporangium wall with thickenings in the form of longitudinal
ribs connected by delicate threads.
ORDER 2. Liceaceae.
Sporangia solitary, sessile or stalked ; sporangium wall cartilaginous ;
capillitium and columella absent. Genera — Licea, Schrader. Sporangia
sessile, globose or in the form of plasmodiocarps. Orcadella, Wingate.
Sporangia stalked, furnished with a lid of thinner substance.
ORDER 3. Tubulinaceae.
Sporangium wall membranous, without granular deposits ; sporangia
tubular, compacted together. Genera — Tubulina, Pers. Columella
absent. Siphoptychium, Rost. A hollow pseudo- columella is present,
connected by tubular extensions with the sporangium wall. Alvrisia,
Berkeley and Broome. Sporangia stalked ; with tubular threads attached
to the base and apex of the sporangium wall.
ORDER 4. Reticulariaceae.
Aethalia, with the sporangium walls incomplete, perforated, and
forming a spurious capillitium. Genera — Dictydiaethalium, Rost.
Sporangium walls cap -shaped above and continued down to the base
in four to six straight threads. Enteridium, Ehrenberg. Walls of
64 THE MYCETOZOA
convoluted sporangia forming a tissue of interarching bands. Reticularia,
Bulliard. Walls of convoluted sporangia forming tubes and folds with
numerous anastomosing threads.
ORDER 5. Lycogalaceae.
Sporangia forming an aethalium ; pseudo-capillitium consisting of
branched colourless tubes, the remains of the walls of the fused sporangia.
Genus — Lycogala, Micheli.
SUB-COHORT B. CALONEMINEAE.
Capillitium a system of uniform threads.
ORDER 1. TricMaceae.
Capillitium threads with spiral or annular thickenings. Free or
united into an elastic network. Trichia, Haller (Figs. 11, 12, and 15, a-c).
Capillitium abundant, threads free, with spiral thickenings. Oligonema,
Rost. Capillitium scanty, threads free, with imperfect spiral thickenings.
Hemitrichia, Rost. (Fig. 15, d). Capillitium threads combined into a net-
work, with spiral thickenings. Cornuvia, Rost. Sporangia in the form
of plasmodiocarps ; Capillitium threads combined into a network, with
annular thickenings.
ORDER 2. Arcyriaceae.
Capillitium combined into an elastic network with thickenings in the
form of cogs, half-rings, spines, or warts. Genera — Arcyria, Hill (Fig.
15, e-/). Sporangia stalked ; sporangium wall evanescent above, persistent
and membranous in the lower third. Lachnobolus, Fries. Sporangia
sessile, clustered ; sporangium wall single, persistent, not thickened with
granules. Perichaena, Fries. Sporangia sessile or in the form of plas-
modiocarps ; sporangium wall double, at least at the base, the outer layer
thickened with angular granules.
ORDER 3. Margaritaceae.
Sporangia normally sessile ; sporangium wall single, smooth, trans-
lucent ; capillitium abundant, not consisting of separate threads, nor
combined into a net. Genera — Margarita, Lister. Capillitium profuse,
long, coiled, and hair-like. Dianema, Rex. Capillitium of nearly
straight threads, without spiral thickenings, attached at both ends to the
sporangium walls. Prototrichia, Rost. Capillitium of fasciculate threads,
attached above or below to the sporangium wall, and spirally thickened.
DIVISION II. EXOSPOREAE.
Spores developed on the surface of sporophores.
ORDER 1. Ceratiomyxaceae.
Sporophores fragile and evanescent, branched ; spores white, borne
singly on filiform stalks arising from the areolated sporophore. Genus —
Ceratiomyxa, Schroeter (Fig. 18).
THE MYCETOZOA 65
SUB-CLASS II. SOROPHORA.
A flagellate stage is absent from the life -history. The amoebulae
become aggregated prior to spore-formation, but do not fuse to form a true
plasmodium. In the more highly developed genera some of the aggregated
amoebulae are modified to form a stalk on which the remainder are borne
after encystment in naked clusters (sori).
ORDER 1. Guttulinaceae.
The aggregation of amoebulae, prior to spore-formation, to form the
pseudo-plasmodium, is incomplete in Copromyxa. The amoebulae have
the Umax form, and the shape of the sori is indefinite.
Genera — Copromyxa, Zopf (Fig. 19, a and 6). Sori wart-like or
spindle-shaped, 1-3 mm. high, formed on the surface of the nidus. None
of the amoebulae are differentiated to form a stalk. On horse and cow
dung. Guttulina, Cienk. Some of the aggregated amoebulae are dif-
ferentiated to form a short stalk on which the sorus is borne. On decaying
wood or horse-dung.
ORDER 2. Dictyosteliaceae.
A pseudo-plasmodium is formed prior to spore-formation. Some of
the aggregated amoebulae are modified to form a stalk. The sori have a
definite shape. Amoebulae with short pointed pseudopodia. Genera —
Didyostelium, Brefeld. Stalks unbranched, the spores without definite
arrangement in the sori. On dung of herbivorous animals. A cram, van
Tieghem. Spores arranged in rows, like strings of beads, at the ends of
the stalks. On beer-yeast. Polysphondylium, Brefeld (Fig. 19, c and d).
Sori globular, on branched stalks, which attain 1 cm. in length. On
horse-dung.
POSTSCRIPT.
Since the foregoing account of the Mycetozoa was written papers .have
been published, in part of a preliminary character, which appear to throw
light on the nuclear history.
In the Endosporeae, Fraulein H. Kriinzlin l has described a fusion of
the nuclei in pairs, prior to the mitosis which precedes spore-formation, in
the young sporangia of Arcyria, and this result is corroborated by Jahn.2
The number of chromosomes at this division Jahn believes to be sixteen
(" 8 double chromosomes ") in Arcyria (at least double that which Jahn
found in the division of the zoospore in other genera). In Fuligo Harper 3
found the number to be twelve in the mitosis preceding spore-formation.
1 " Zur Entwicklungsgescluchte der Sporangien bei den Trichien und Arcyrien,"
Arch.f. Protistenkunde, Bd. ix. (1907), p. 170.
2 " Myxomycetenstudien — 6. Kernverschmelzungen und Reduktionsteilungen,"
Eer. d. deutsch. botan. Gese.llschaft, Bd. xxv. (1907), p. 23.
3 "Cell and Nuclear Division in Fuligo varians," Botanical Gazette, vol. xxx.
(1900), p. 217.
66 THE MYCETOZOA
These authors suggest that the fusion of nuclei in the young sporangium
is a long-deferred karyogamy, separated by the whole of the plasmodium
stage, with its many nuclear divisions, from the plastogamy (the fusion of
the amoebulae) by which the plasmodium originates. They thus regard
the mitosis preceding spore-formation as the one nuclear division in the
life-cycle in which the full ("somatic") number of chromosomes is present.
Jahn (I.e.) and, subsequently, Olive1 also state that a fusion of nuclei
occurs in Ceratiomyxa prior to the formation of the spores. The fusion is
followed by four according to Jahn, by two according to Olive, mitotic
divisions, and the ripe spore is four-nucleated (not one-nucleated, as in-
dicated above (Fig. 18, c)).
It would thus appear that there are, at any rate, two mitotic divisions
before spore-formation in Ceratiomyxa and only one in the Endosporeae.
The spores are thus not strictly homologous in the Endosporeae and
Exosporeae. That of Ceratiomyxa is more advanced than the spore of the
Endosporeae in that at least two mitotic divisions subsequent to karyogamy
have occurred (and the four nuclei thus arising are contained in the spore),
but it is less advanced in that no cleavage of the protoplasm about the
products of division has taken place.
LITERATURE.
1. de Bary, A. Die Mycetozoen. Zeits. f. \viss. Zool. vol. x. (1860), p. 88.
2. Die Mycetozoen. 2e Auflage, Leipzig, 1864.
3. Comparative Morphology and Biology of the Fungi, Mycetozoa, and
Bacteria. Translation. Oxford, Clarendon Press, 1887.
4. Butschli, 0. Protozoa, Abth. g, Sarcodina. Bronn's Thierreich, Bd. i.
5. Cienkowski, L. Die Pseudogonidien. Priugsheim's Jahrbiicher, i. p. 371.
6. Zur Entwickelungsgeschichte der Myxomyceten. Pringsheim's Jahr-
biicher, iii. p. 325 (published 1862).
7. - Das Plasmodium. Ibid. p. 400 (1863).
8. Beitrage zur Kenntniss der Monaden. Arch. f. mikr. Anat. i. (1865),
p. 203.
9. Famintzin, A., and Woronin, M. Ueber zwei neue Formen von Schleimpilzen,
Ceratium hydnoides, A. and Sch., and C. porioides, A. and Sch. Mem. de
1'Acad. Imp. d. Sciences de St. Petersbourg, ser. 7, T. 20, No. 3 (1873).
10. Greenwood, M., and Saunders, E. E. On the Role of Acid in Protozoan
Digestion. Journ. of Physiology, xvi. (1894), p. 441.
11. Jahn, E. Myxomycetenstudien — 3. Kerntheilung u. Geisselbildung bei den
Schwarmern von Stemonitis flaccida, Lister. Ber. d. deutschen botanischeu
Gesellschaft, Jahrg. 1904, Bd. xxii. Heft 2.
12. Krukenberg. Ueber ein peptisches Enzym im Plasmodium der Myxomyceten
und im Eidotter vom Huhne. Uuters. aus d. physiol. Inst. in Heidel-
berg, 1878, ii. p. 273.
1 " Cytological Studies in Ceratiomyxa," Trans. Wisconsin Academy of Science,
Arts, and Letters, vol. xv. (1907), pt. 2, p. 753 ; and "Evidences of Sexual Repro-
duction in Slime Moulds," Science (N.S.), vol. xxv. (1907), p. 266.
LITERATURE OF THE MYCETOZOA 67
13. Lcinkcster, E. R. Article "Protozoa" in Encyclopaedia Britannica, 1891.
14. Lister, A. Notes on the Plasmodiurn of Badhamia utricularis and
Brefeldia maxima. Ann. of Bot. vol. ii. No. 5 (1888).
15. On the Ingestion of Food Material by the Swarm-Cells of Mycetozoa.
Journ. Linn. Soc. (Botany), vol. xxv. (1889), p. 435.
16. - - On the Cultivation of Mycetozoa from Spores. Journ. of Botany,
Jan. 1901.
17. — - On the Division of Nuclei in the Mycetozoa. Journal of the Linnean
Soc. (Botany), xxix. (1893).
18. A Monograph of the Mycetozoa. Brit. Museum Catalogue. London,
1894.
19. Metschnikoff, E. Recherches sur la digestion intracellulaire. Annales de
1'Institut Pasteur, 1889, p. 25.
20. Olive, E. W. Monograph of the Acrasieae. Proc. Boston Soc. of Nat.
History, vol. xxx. No. 6 (1902).
20«. Peiuird, E. ]5tude sur la Chlamydomyxa montana. Arch. f. Protisten-
kunde, Bd. iv. Heft 2 (1904), p. 296.
21. Plenge, H. Ueb. d. Verbindungen zwischen Geissel u. Kern bei d.
Schwarmerzelleu d. Mycetozoen . . . Verb. d. nat.-hist. med. Vereins
zu Heidelberg, N.F. Bd. vi. Heft 3, 1899.
22. Stahl, E. Zur Biologic der Myxomyceten. Bot. Zeitung, .Jahrg. 42
(1884), pp. 145, 161, and 187.
•23. Strasburger, E. Zur Entwickelungsgeschichte d. Sporangien v. Trichia
fallax. Botanische Zeitung, 1884.
24. Zopf, W. Die Pilzthiereo der Schleimpilze. Schenk's Handbuch der
Botanik, 1887.
25. Zur Kenntniss der Labyrinthuleen, einer Familie der Mycetozoa.
Beitrage zur Physiologie u. Morphologic niederer Organismen. Heft 2
(1892), p. 36, Leipzig.
THE PEOTOZOA (continued)
SECTION D. — THE LOBOSA l
GYMNOMYXA (Homokaryota), with lobate or pointed unbranched
pseud opodia without an axis and with one or more definite nuclei.
In a large number of the characteristic genera of Lobosa the
body consists of a small plastid of protoplasm protruding a few
lobate pseudopodia by means of which a slow progression is
effected, and exhibiting one nucleus and a contractile vacuole.
In addition to these characteristic forms, however, other genera
must be included in the same class in Avhich the body is protected
by membranous or rigid shells (Thecamoebida), with radiating and
pointed pseudopodia (Trichosphaerium, etc.), with two (Arcella), or
numerous nuclei (Pelomyxa), and with no contractile vacuole
(Endamoeba, etc.).
In many Lobosa, such as Amoeba terricola (Penard [20]) and
others, the superficial protoplasm secretes a membranous envelope
through which the pseudopodia may be protruded or particles of
food ingested. In Trichosphaerium the envelope is relatively
thick, gelatinous in texture, and provided with a series of very
delicate radiating spicules, mainly composed of carbonate of
magnesia. Spicules similar to these are also found in the ecto-
plasm of Amoeba pilosa (Cash), in which no true membrane is
formed. In Dinamoeba (Leidy) the spicules occur in a hyaline
jelly that surrounds the body.
In the Thecamoebida a definite shell is formed through which
the pseudopodia cannot penetrate. In this case the pseudopodia
can protrude only through a definite and permanent mouth or
pore in the shell, which it is convenient to call the pylome (Hartog).
In some forms of Amoeba and in other genera there is
often seen an apparent differentiation of the protoplasm into a
clear outer layer, called the ectoplasm, and a more granular and
more fluid central substance called the endoplasm. This appear-
ance is more clearly defined when the protoplasm is very active
and several pseudopodia are protruded. In the quiescent stages
and conditions of life the ectoplasm usually disappears or becomes
extremely attenuated, and in species or forms with only one or two
1 By Prof. S. J. Hickson, M.A., F.R.S.
68
THE LOBOSA 69
pseudopodia it can be clearly observed only on the pseudopodia
themselves (Fig. 12, 2). It seems probable, therefore, that in the
Lobosa there is no true differentiation of the cytoplasm, and that
the appearance known as ectoplasm is only due to the temporary
withdrawal of metaplasmic particles from the superficial parts of
the active cytoplasm.
At the surface of an Amoeba there may always be seen a dark
border which has the appearance of a very thin pellicle. This
pellicle may be traced on the sides of the pseudopodia, but fades
away towards their extremities, becoming extremely attenuated at
the active terminal point. Immediately below this pellicle there
is a layer of very hyaline ectoplasm. In carefully prepared sections
the hyaline ectoplasm is found to be not strictly homogeneous, but
to possess an alveolar structure similar in general characters to that
of other forms of protoplasm. At the actual surface there is a
single layer of alveoli, in which, as in artificially prepared oil foams,
the sides vertical to the surface are parallel, or almost parallel, to
each other, giving the appearance of a row of fine vertical striae. It is
apparently this marginal alveolar layer which constitutes the pellicle.
The movements of an Amoeba may be best interpreted on the
basis of the alveolar hypothesis of the structure of protoplasm.
The protrusion of a pseudopodium begins with a lowering of
the surface tension of the marginal alveolar layer over a small area
on the surface. This is followed by a flow of endoplasm towards
the area of reduced surface tension. It has been suggested that
the initial stages are accompanied by a rupture of some of the
alveoli at the surface, which liberates a fluid — the enchylema — and
that this causes a local diminution of the surface tension. It is
possible that the release of enchylema may continue during the
whole of the process of the protrusion of a pseudopodium, and
stop when the pseudopodium comes to rest. During the active
protrusion of a pseudopodium there may be observed a rapid
centrifugal flow of endoplasm towards the peri-
phery, called the axial stream. At the apex this
stream spreads outwards like a fountain, and is
continued as return currents on the surface. Similar
fountain-like currents have been observed in the
movements of various artificially prepared foams,
but in the living protoplasmic pseudopodium the
velocity of the return currents diminishes more FIG. i.
rapidly and soon comes to rest (Fig. 1). In an Diagram to show
Amoeba such as A. Umax, in which, as a rule, only ° °
one pseudopodium is formed, there is a reverse
fountain current at the posterior end, the particles at
the surface flowing towards the axis and joining in the axial stream
flowing in the direction of the advancing pseudopodium. But in
THE LOBOSA
this case the actual posterior end is not involved in the current, and
by the increase of surface tension becomes folded or wrinkled, giving
sometimes an appearance of several small pseudopodia (Fig. 12, 2).
In polypodious Amoebae similar reverse currents may be ob-
served in retreating pseudopodia, and in areas of the body
that are supplying materials for the axial streams of advancing
pseudopodia.1
Nucleus. — The nucleus of the Lobosa in its resting condition
usually exhibits a well-defined membrana liniitans. The chromatin
is in the form of a number of spherical or irregular particles frequently
collected together round the periphery, leaving a more or less clear
space in the centre. In some cases a very delicate network of
fibrils has been observed, which is regarded as linin (Fig. 2).
One or more nucleoli composed of a substance which differs
chemically in some of its reactions from chromatin
may or may not be present.
In Paramoeba eilhardi there occurs a deeply
staining body in proximity to the nucleus, which
was termed by Schaudinn (25), who described it,
the " nebenkorper " (Fig. 4, c). This body divides
previous to the division of the nucleus, and the
two parts take up a position at opposite poles of
the spindle. This body is usually regarded as a "nucleolar cen-
trosome." A body corresponding to this has also been found by
FIG. 2.
Nucleus of Pelomyxa.
(After Bott.)
m,L.-
ch, '
Fio. 3.
Dividing nucleus of
Amoeba Umax, m.l, the
meinbraua liini tans of the
nucleus ; c, the nucleo-
lar centrosome ; eh, the
chromosomes arranged
iu an equatorial band.
(After Vahlkampf.)
FIG. 4.
The resting nucleus
(.V) and "nebenkorper"
(c) of Paramoeba eilhardi.
(After Schaudinn.)
Fio. 5.
The nucleus of the
same species dividing.
The "nebenkorper" (c)
has divided into two
parts, which occupy a
position at the foci of the
central spindle, eh, the
chromosomes arranged
in an equatorial band.
(After Schaudinn.)
Vahlkampf in the division of the nucleus of Amoeba Umax (Fig. 3),2
but in this case the nucleolar centrosome lies within the nuclear
membrane.
1 The subject of amoeboid movements has of recent years attracted the attention
of many observers. The views expressed by Biitschli (Investigations on Microscopic
Foams, etc., transl. by Minchin, 1894) have been opposed by Jennings (14),
but Jennings' views have been more recently criticised by Rhunibler (23).
2 For a discussion on the nature of these bodies, see Goldschmidt and Popoff,
Archivf. Protist. viii., 1907, p. 321.
THE LOBOSA
Although the presence of a defined nucleus is regarded as one
of the characters of the class, it has been shown that the nuclei
sometimes disintegrate and discharge their, chromatin into the
cytoplasm as scattered granules. This occurs as a result of
starvation in Pelomym (Bott [2]), and as an antecedent to the
formation of sexual or reproductive nuclei in Endamoeba.
Chromidia. — In addition to the chromatin contained within the
boundaries of the nuclei, there may be present in the cytoplasm of
many Lobosa irregular scattered granules or a fine network of a
substance which gives the same reactions and is probably of the
same nature as chromatin.
In some cases, Difflugia (Fig. 6), the network entirely envelops
the nucleus or nuclei, but in others it is separated from the nuclei,
Arcella, Cochliopodimn, etc. (Figs. 19 and
21), by a halo of clear protoplasm.
These granules are called the
chromidia, and the network is called the
chromidial network (Fig. 6, ch). The
chromidia may arise by the migration of
particles of chromatin from the nucleus
into the cytoplasm or by the disintegra-
tion of nuclei, but it seems probable that
in some cases they may arise de now
in the cytoplasm.
The fate of the chromidia is varied.
They may either give rise to the nuclei
nf <y;iTnpfp<3 nr nf <5\virm «innvp<5 (Tpnirn
'I gametes S (^eniW-
v>/.?is\ or they may accumulate in groups by the chromidial network (ch). r,
*9 n . .» J i . * i pylome; th, theca wall. (After
and give rise to new nuclei of the Hertwig.)
ordinary type in the cytoplasm (Arcella,
I'elomyxa), in which cases they are called Idiochromidia. Or, on
the other hand, they may be associated with the assimilating or
vegetative functions of the cytoplasm and disappear when their
activity is exhausted, in which case they are called Trophochromidia.
Refringent and Crystalline Bodies. — In many Lobosa crystalline
bodies and vesicles containing a strongly refracting substance or
fluid occur in great numbers in the cytoplasm. Very often they
are far more numerous and conspicuous during the stages and
conditions of life when active feeding is in progress than in
conditions of starvation or reproduction. They are usually
regarded as of the nature of reserve food materials.
In Amoeba dofleini, Neresheimer (18) found that the crystalline
body, proteid in composition, is associated with a trophochromidium
which is probably the active principal of its formation. Veley (34)
has shown that the refracting bodies of Pelomym are proteid in nature.
On the other hand, Zuelzer (35} has described the bodies
FIG C.
Section through Difflugia sp. ?
showing the nucleus (A') surrounded
THE LOBOSA
formed by the trophochromidia of Difflugia as carbohydrate in
composition, but the crystalline and other bodies of Trichosphaerium,
according to Schaudinn, give differ-
ent reactions.
Vacuoles. — In nearly all the
freshwater and marine Lobosa there
is at least one contractile vacuole.
In Pelomyxa and some of the Theca-
moebida, however, contractile vac-
uoles have not been found. The
endoparasitic Amoebida have no
contractile vacuoles. In addition
to the contractile vacuole numerous
non- contractile vacuoles containing
a fluid of unknown constitution
FIG. 7.
re, refringent proteid bodies ; b, symbi-
otic bacteria (Cladothnx) ; chr, scattered
chromidia ;», water vacuoles. (After Bott.)
water
occur jn the endoplasm.
f
When a particle of food OCClirs
in a non-contractile vacuole it. is
usually called a food-vacuole, and the fluid in such vacuoles has
been shown in some cases to be slightly acid in reaction and
probably contains a digestive ferment.
In Arcella and in other Thecamoebida vacuoles containing a
gas are found within the shell. These vacuoles serve hydrostatic
functions.
Reproduction — Fission, — Reproduction by fission has been
proved to occur as a normal process in many of the genera of
Lobosa. In Amoeba and allied genera the result
of fission is a pair of equal -sized daughter
r* a~±-\
Fio. S.
Daetylosphaera polypodia, M. Schultze, in three successive stages of division. The stages
indicated occupied fifteen minutes, a, nucleus ; b, contractile vacuole. (After F. B.
Schultze.)
Amoebae. In Pelomyxa, Trichosphaerium, and probably in other
multi nucleated Gymnamoebida, fission may be unequal.
In the Thecamoebida one of the individuals of the act of fission
retains the shell, and the other sooner or later forms a new shell
which is usually larger than that of the parent.
THE LOB OS A 73
The process of fission is usually preceded by division of the
nucleus, or in the binucleate Amoebae of both nuclei.
In some species (Amoeba binucleata and Paramoeba eilhardi,
Schaudinn (Figs. 4 and 5), A. Umax, Vahlkampf, and Amoeba proteus,
Awerinzew) the division of the nucleus shows some of the charac-
ters of ordinary mitosis. The chromatin is collected together into
a large number of short chromosomes arranged in an equatorial
row. They then divide and travel in two equal parties along
faintly stained and nearly parallel lines, supposed to be of
the nature of linin, towards the opposite poles of the nucleus,
where they unite to form the chromatin network of the daughter
nuclei. The threads of the figure do not always converge at the
poles to a focal point, and as a general rule it is doubtful whether
structures exactly similar to the centrosomes of the metazoan nuclei
occur. Centrosomes, however, have been described and figured
in the division of the nuclei of Pelomyxa (Bott [2], Fig. 11, a).
Notwithstanding the evidence of a primitive kind of mitosis in
the division of the nuclei in these and other species, the division of
the nucleus of Amoeba crystalligera, of A. hyalina, of Dactylosphaera
polypodia, and of Endamoeba coli (Schaudinn) is amitotic.
In Pelomyxa and Trichosphaerium fission usually consists in the
pinching off of globules from the body, each containing a few
nuclei. These globules rapidly assume the characters of the
parent; they increase in size and the number of the nuclei is
.augmented. This process may be regarded as a case of unequal
fission or of gemmation, but it appears to differ from the equal
fission of some species of Amoeba in the respect that antecedent
•division of the nuclei is not an essential preliminary to division of
the cytoplasm. In a large multinucleate form of Amoeba proteus,
Stole (31) has found that division of the nuclei may or may not
take place before fission ; and in some cases some of the nuclei
divide and others do not before an act of fission.
Encystment and Spore-Formation. — It is now known that many
of the Gymnamoebida periodically undergo a process of encystment
in which the pseudopodia are withdrawn, the body becomes more
or less spherical, and one or more tough membranes are formed
which entirely surround and protect the animal. In some cases
these cysts appear to be of the nature of resting cysts (Amoeba
Umax, Vahlkampf [33]), the organism emerging from the broken
•cyst-wall with the same characters it possessed previous to cyst-
formation. The formation of resting cysts probably occurs in all
the Thecamoebida. In many cases, however, the encystment is
accompanied by complicated nuclear changes and divisions followed
by division of the cytoplasm, and a swarm of minute spores that
.are often very different in character from the parent form are
hatched out when the cyst-wall breaks down.
74
THE LOBOSA
In the case of Endamoeba coli (Schaudinn [36]), for example,
the uninucleate amoeboid form discharges all foreign bodies from
its cytoplasm and becomes surrounded by a clear, soft, jelly-like
envelope. Within the cyst-wall it divides into two equal parts
each with a single nucleus, and these two parts remain separate
for a considerable time. The two nuclei then fragment, their
chromatin being scattered in the cytoplasm as isolated chromidia.
The two nuclei are now reconstructed, but each reconstructed
nucleus is relatively poor in chromatin. Each of these nuclei now
divides into two by a primitive kind of mitosis ; one of them from
each half-amoeba is rejected as a polar nucleus and the remaining
one divides again. At this stage in the process the protoplasm
contracts, the gelatinous membrane disappears, and the cyst
is surrounded by a harder membranous wall. The daughter
nuclei of this mitosis conjugate reciprocally with the daughter
nuclei of the other half-amoeba, and each of the two zygote nuclei
thus formed divides twice. The eight nuclei thus formed become
the nuclei of eight amoebulae which escape from the cyst.
In Amoeba proteus also, according to Scheel, division of the
nucleus and cytoplasm takes place during the encystment, and
FIG. 9.
A, cyst of Amoeba proteus ; abc, cyst-wall ; d, gelatinous envelope ; K, F, nuclei ; 0, albu-
minous bodies, x 300. (After Scheel.) B, cyst of Endamoeba blattae, with 25 nuclei. (After
Schubotz.)
a swarm of small amoebulae emerge from it when the cyst breaks
down. In this case, however, there is no evidence that any form of
nuclear conjugation takes place during the encystment.
Conjugation. — Although the complete life-history of only a few
species of the Lobosa has, at present, been fully worked out, the
evidence is accumulating to justify the conclusion that a process of
conjugation is an essential condition for the completion of the life-
cycle in all forms. The process of conjugation has not yet been
observed in Amoeba proteus or in any of its allies. Nuclear con-
jugation accompanied by fusion of the cytoplasm occurs during,
encystment in Endamoeba coli.
THE LOBOSA 75
In Pelomyxa (Bott [2]) amoeboid isogametes are discharged
from the body with a nucleus formed in a manner that suggests
that the number of the chromosomes is reduced (infra, p. 76).
These gametes conjugate to form a zygote (Fig. 10), which may
subsequently encyst.
In Trichosphaerium (Schaudinn [26]) a large number of
biflagellate isogametes escape from the cyst and by exogamous
conjugation form zygotes which become amoeboid in character.
Biflagellate isospores arise from the cystic stage of Paramoeba
eilhardi, but there is no evidence, at present, to show that they
conjugate.
In Centropyxis (Schaudinn [27]) heterogametes are formed
which have a shell. After conjugation the zygote escapes from
the shell and forms a new one like that of the adult individual.
Life-History. — The recent rapid advance in our knowledge of
the life-history of Lobosa, due in large measure to the researches
of Schaudinn and R. Hertwig, suggests that in all cases the
developmental cycle that is passed through is both complicated and
varied.
In order to illustrate the general character of these life-
histories, four examples may be taken for description.
Endamoeba coli is found in the upper part of the human large
intestine, but unlike Endamoeba histolytica it does not appear to be
the cause of or associated with any particular form of disease. It
undoubtedly occurs in perfectly normal and healthy hosts.
During the ordinary vegetative life in the intestine it multiplies
by simple fission with amitotic division of the nucleus. Occasionally
schizogony occurs, when the nucleus divides into eight by successive
mitoses and each of these nuclei becomes the nucleus of a daughter
amoebula. After a certain period of vegetative life, the normal
duration of which has not been estimated, the uninucleated amoebae
become encysted, and in that condition are passed into the lower
part of the large intestine, and so to the exterior with the faeces.
The complicated divisions and the conjugation of the nuclei during
and antecedent to complete encystment have already been described.
Many of the cysts undoubtedly perish, but the cysts with eight
nuclei when swallowed by another host will give rise to eight
amoebulae which infest the intestine of the new host. The cysts
with more than eight nuclei that are sometimes found in the faeces
are, according to Schaudinn, degenerating cysts, and never give rise
to active amoebulae.
In Trichosphaerium, a marine rhizopod with peculiar radiate
pseudopodia and many nuclei, there are two phases in the life-cycle.
In the first phase the gelatinous investment is armed with radiating
apicules. It reproduces itself in this phase by simple binary or by
multiple fission, the pseudopodia being previously Avithdrawn. In
THE LOB OS A
the second phase, in which the radiating spicules do not occur,
reproduction -may also occur in a manner similar to that of the first
phase, but at the conclusion of vegetative growth the pseudopodia
are withdrawn, all foreign bodies and excreta are expelled, and a
cyst is formed. The nuclei then divide rapidly by repeated mitoses
to form an immense number of minute nuclei. These nuclei become
the nuclei of minute biflagellate swarm-spores (gametes), which escape
from the gelatinous investment of the cyst, and after conjugation
give rise to small individuals of the first phase.
In Pelomj/xa, a multinucleate freshwater rhizopod (Fig. 14), repro-
duction is effected by simple or multiple fission during the vegetative
period of life, but at certain times,
after a complicated series of
nuclear divisions in which a re-
duction in the number of chro-
mosomes occurs, uninucleated,
heliozoan-like swarm-spores escape
which conjugate to form a zygote,
and this encysts. From the cyst
a uninucleated amoebula escapes,
which by growth and multipli-
cation of the nucleus gradually assumes the typical Pelomyxa form.
In the preparation of the nuclei for the formation of the gametic
nuclei, a considerable part of the chromatin is discharged into the
cytoplasm, and from that which remains eight chromosomes are
formed on the equatorial band of a central spindle (Fig. 11, a). Two
successive divisions take place, the first of which is regarded as a
reduction division, and the
second as an equation division.
The chromatin of the four
chromosomes of this last
division collect together in
two lumps, and a transparent
globular vacuole appears in
their immediate neighbour-
hood. This vacuole gradually
fills with minute granules
Fio. 10.
Zygote of Pelomyia palustris. a, encysted.
I, after escape from the cyst. (After Bott.)
chr.
FIG. 11.
Nuclear formation in Pdomyxa, a, the spindle
of the reduction division with eight chromo-
somes, b, the nucleus (AT) of the gamete forming
in a clear vacuole. ch, the chromatin lumps of
which rapidly increase in Size the last nuclear division. (After Bott.)
and gives rise to the nucleus
of the gamete (Fig. 11, b). The chromatin lumps at the same time
dwindle and eventually disintegrate.
In Centropyxis, one of the Thecamoebida, binary fission occurs
by the protrusion and division of the protoplasm preceded by
amitotic division of the nucleus. One portion of the divided proto-
plasm with one nucleus returns to the old shell, the other forms a
new shell but of a larger size. It does not seem certain Avhether
THE LOBOSA 77
the individual retained by the old shell is or is not capable
of further reproduction, but the occurrence of an immense number
of empty shells in cultures of Centropyxis and its allies suggests that
it may die after one act of fission. The individual that has formed
a new and larger shell, however, certainly divides again, giving rise
by a similar process to a daughter individual with a still larger
shell. When by these processes of fission the full size is reached,
the nucleus degenerates, after giving rise to an expanded chromidial
network which, with about two-thirds of the protoplasm, protrudes
from the mouth of the shell, is pinched off, and escapes. The
remaining one-third of the protoplasm and the degenerate nucleus
that remain in the shell probably die.
The escaped protoplasm may give rise to one of two broods of
gametes. In one brood (the megagametes) the chromidia give rise
to a nucleus and the protoplasm forms a shell ; in the other, after
a nucleus is formed from the chromidia and a shell is formed as
in the first brood, a division into four individuals (the microgametes)
takes place, and each of these escapes and forms a small shell.
Conjugation takes place between the larger and smaller individual
gametes, and the zygote escapes to form a new shell like that of
the parent.
ORDER Gymnamoebida,
The surface of the body either naked or provided with a
thin flexible membrane through which the pseudopodia can be
protruded.
Genera Amoeba. — The generic name Amoeba is often applied
to any naked amoeboid organism without reference to its subsequent
or antecedent history. As our knowledge of the natural history
of the simpler Protozoa widens it becomes more evident that the
generic name should be used only in a restricted sense. The limits-
we place upon the use of the generic name can only be regarded
as provisional. Further investigations may well prove that the
species now included in the genus Amoeba, ought to be still further
separated into subgeneric or generic groups.
The characters of the genus may be summarised as follows : —
Solitary Gymnamoebida, with a few short blunt pseudopodia, a
single contractile vacuole, and one or more nuclei. No membrane
covering the body in the trophic phase of life. Freshwater or
marine.
Nine or ten distinct species have been described from fresh
water in this country (Cash). They are usually found in the mud
at the bottom of ponds or creeping on submerged vegetation.
Some of the rarer forms are found in Sphagnum bogs. One of the
commonest species is Amoeba proteus (Fig. 12, 5), a species capable
of considerable variation in form, but usually exhibiting several
THE LOBOSA
digitiform pseudopodia. In this species there may be either one or
many nuclei. It may reach a size of 200 /A in diameter. A. guttula
(Fig. 12, 4) is another very common species of small size, 30 /A, which
shows slow undulating movements of the ectoplasm but rarely
protrudes definite pseudopodia. In Amoeba Umax (Fig. 12, 2), which
is slug-like in form, the end that is posterior in progression shows
a fan -shaped arrangement of short ridges, due probably to the
FIG. 12.
Different species of freshwater Gymnamoebida. 1, Dactylosphaera radiosa, x 260. 2,
Amoeba Umax, x 200. 3, Amoeba verrucosa, x 200. 4, Amoeba guttula, Duj., regarded as a young
form of A. proteus by Leidy. 5, Amoeba proteus. 6, Amoeba (Ouramoeba) vorax, x 130. N,
nucleus ; c.v, contractile vacuole ; F.v, food vacuole ; F, hyphae of a fungus. In Amoeba vorax
some of the large diatoms (D, D) upon which it feeds and the approximate positions of the
nucleus and contractile vacuole are shown. (1, 2, 3 from Cash ; 4, 5, 6 from Leidy.)
wrinkling of the surface in the vortex of the retreating axial stream
.{see p. 69).
The marine Amoebae have not yet been carefully recorded.
Amoeba crystalligera is often found in marine aquaria, and a species
allied to the freshwater A. guttula has been found at Woods Hole
in America. Amoeba fluida was found in sea- water aquaria in
Freiburg by Gruber, and this with two other species were also
found by him in the Gulf of Genoa.
THE LOBOSA 79
It may be regarded as extremely doubtful whether the forms
that the Amoebae present really indicate true differentiation into
definite species, or represent the varying influence of certain ex-
ternal conditions acting upon one species, or, again, represent
different phases in the life - history of one or more distinct
species. Thus it has been observed that when the amoebae
found on the surface of decomposing hay infusions are placed upon
a slide, broad lobate pseudopodia begin gradually to be extended
in various directions and the general form of Amoeba, proteus is
assumed. After a time, when progression may be induced in one
direction, the body becomes elongated and more or less pointed at
the anterior end, so that the form becomes similar to that known
as A. Umax. If the water be made very feebly alkaline the amoebae
contract into a spherical shape with very short dentate pseudopodia,
similar to A. guttula, and then protrude long pointed pseudopodia
similar to those of Dadijlosphaera radiosa.1
The forms usually attributed to the genus Ouramoeba, Leidy,
have been shown to be Amoebae in which fungal filaments are
growing (Poteat [21]). The filaments arise from spores which are
always situated in the neighbourhood of the contractile vacuole. It
has been suggested that the fungus receives nourishment from the
waste products of the amoeba. These filaments have been observed
in Amoebae attributed to the species A. villosa, A. linucleata, and
A. proteus.
The life -history of no species of Amoeba has yet been fully
worked out, but Calkins (7) has shown that Amoeba proteus
normally passes through an early stage when the pseudopodia are
relatively long and more pointed and similar to those of A. radiosa ;
and Scheel (29) has proved that the uninucleate condition is
succeeded by a multinucleate condition previous to encystment.
Calkins suggests that the life-cycle of Amoeba proteus may be
somewhat as follows : — The zygote gives rise to a small radiate
form, which develops into the uninucleate type-form. This
encysts and by schizogony gives rise to uninucleate Amoebae,
which develop into the multinucleate type-form. The multi-
nucleate type-form encysts and gives rise to the gametes, which
conjugate to form the zygotes.
Paramoeba, Schaudinn. Several radiating pseudopodia. A well-
defined chromatin body is present in tlie cytoplasm close to the nucleus.
Swarm-spores with two flagella. P. eilhardi was found in a marine
aquarium in Berlin. 10-90 /JL. P. hominis, a human parasite (p. 83).
Dactylosphaera, Hertwig and Lesser (Fig. 12, 1), is distinguished from
Amoeba by the numerous rigid pseudopodia, \vliich do not completely
retract when at rest. Freshwater. Maximum 120 /*.
1 Verworn, General Physiology, English translation, 1899, p. 184 ; and Dofleii),
F., Archiv Prot. Suppl., 1907, p. 250.
8o
THE LOBOSA
Lithamoeba, Lankester1 (Fig. 13). Body discoid, pseudopodia lobular
and hernia-like. A distinct pellicle covering the body, which ruptures
for the protrusion of the pseudopodia. Freshwater. Maximum 125 p.
Dinamoeba, Leidy. Pseudopodia long, conical, and acute. Body
enveloped in a delicate hyaline jelly bristling with minute spicules.
Bogs of New Jersey. 60-160 /A.
The following genera were described by Frenzel (8, 9) from fresh
water in the Argentine Republic : Chromatella, Stylamoeba, Saltonella,
and Eikenia.
Centrochlamys, Claparede and Lachmaun. The body covered with a
thin, membranous, disc-shaped test through which the pseudopodia pro-
Fio. 13.
Liihamoeba diseus, Lank. A, quiescent; B, throwing out pseudopodia. c.?', contractile
vacuole, overlying which the vacuolated protoplasm is seen ; cone, concretions insoluble in
dilute HC1 and dilute KHO, but soluble in strong HC1 ; /, food particles ; n, nucleus. (After
Lankester.)
trude. No definite pylome. A single nucleus and several contractile
vacuoles. Freshwater. 40-45 p..
Amphizonella, Greeff. Probably closely related to Centrochlamys. The
body is usually invested by a supple membrane which, under some circum-
stances, is itself surrounded by a transparent mucilaginous envelope.
The pseudopodia are pushed through these membranes and withdrawn
again without leaving any definite aperture. It has not been deter-
mined whether the position on the test through which the pseudopodia
protrude is definitely fixed or varies. These two last-named genera
are undoubtedly closely allied to Corycia, Cochliopodium, and other
Thecamoebida.
Hyalodiscus, Hertwig and Lesser. The ectoplasm usually very thick,
and sometimes exhibiting radiating lines. A creeping movement with-
out pseudopodia frequently occurs. One or more inconspicuous nuclei.
Freshwater. 40-60 //,.
Trichosphaerium, Schneider. The structure and life-history of this
genus has been fully described by Schaudinn (26). The body is in-
vested by a gelatinous test perforated by many pores for the protrusion
1 Lankester, Q. J. Micr. Sci. xix., 1879, p. 484.
THE LOBOSA
81
of long digitate pseudopodia ; several nuclei ; no contractile vacuoles.
Zooxanthellae occur in the protoplasm. Marina
Pelomyxa, Greeff. A remarkable genus of Gymnamoebida found in
the mud of ponds and ditches, and distinguished by the presence of an
enormous number of minute nuclei. Several species have been described.
P. palustris, Greeff, P. villosa, Leidy,
are frequently found in this country
and are probably cosmopolitan. P.
penardi, Rhumbler (22), was found
at Gottingen. P. viridis has only
been found in British India.
They vary considerably in size,
but when spread out in progression
P. viridis may attain to a size of 8
mm. in diameter, and the other
species to 2 mm.
The form of the animal is like
that of an amoeba, and progress is
effected by means of numerous
blunt lobose, villiform, or some-
times attenuate and anastomosing
pseudopodia of very variable form
and length. There is neither test FIG. 14.
nor enveloping membrane. Pelomyxa palustris, Greeff. An example
T , . with comparatively few food particles. (After
In the ordinary vegetative con- Qreeff.)
dition of Pelomyxa there are very
many nuclei. Bourne (3) calculated that in a large specimen of P. viridis
there may be 10,000 nuclei. In addition to the nuclei there are numerous
minute scattered chromidia (Bott [2]) (Fig. 7). These chromidia may be
clearly seen in the ectoplasm. The chromidia are formed by the chromatin
discharged from the nuclei, and they never unite to form a chromidial
network. In addition to the nuclei and chromidia, the cytoplasm contains
refringent bodies of a proteid nature (Veley [34]), numerous symbiotic
bacteria, food - vacuoles, and various water - vacuoles, and minute
vesicles.
The refringent bodies appear to be waste materials and probably a
by-product of metabolism, and are undoubtedly used as the food material
of the symbiotic bacteria. They are sometimes ejected from the body,
but in general the Pelomyxa relies on the bacteria as scavengers to
clear its protoplasm of these bodies. The life-history of the symbiotic
bacteria (Oladothrix pelomyxae) has been studied by Veley, who also
determined the proteid nature of the refringent bodies by obtaining the
characteristic reactions with — (1) Millon's reagent ; (2) sugar and sul-
phuric acid ; (3) the xanthoproteic test ; and (4) with caustic soda and
copper sulphate.
The green vesicles described by Bourne in P. viridis appear to be of
the same nature as the refringent bodies, but stained with chlorophyll
The protoplasm of all the species contains a number of vacuoles and
vesicles, but none of them appear to be rhythmically contractile.
82 THE LOB OS A
Endamoeba}- — 'The species of this genus are parasitic in the
intestines of various animals. There is no contractile vacuole, and
rarely more than one short pseud opodium is protruded. Endamoeba
coli is commonly found in the human intestine. It is often present
in perfectly normal health, and is not associated with or the cause
of disease. The size does not exceed 50 p.
Endamoeba histolytica is so similar in size and form to E. coli
in some stages of its life-history that it has been regarded as the
same species, but it is now known to have a different life -history
and to be the active cause of certain
'":::N forms of tropical dysentery. It is
found not only in the ulcers of the
intestinal mucous membrane, but
also in abscesses of the liver accom-
panying the disease. It penetrates
the mucous membrane of the intes-
tine and enters the submucosa
(Dopter [42]).
FIO. 15. The life -history of Endamoeba
Endamoeba coli. A, a specimen with one 7)7e//i7<>;/?V/7 TIQO «r>f Traf V>PPTI -fnllv
nucleus in the resting condition. B,- a ntStOtyttCa Has not yet t
specimen with two nuclei. (After Casa- worked OUt. It is very Similar
grandi and Barbagallo.) . n T
in size and appearance to L. con,
but differs from it in the somewhat indefinite and variable
character of having usually a more distinct hyaline ectoplasm.
According to Lesage (43) the large cysts, similar to those of E. coli,
20 ju, in diameter, are never found in this species. In E. histolytica
the cysts are 3-6 //, in diameter. During the progress of the disease
which it causes it is constantly changing its shape and position, and
asexual reproduction proceeds rapidly by simple fission or multiple
gemmation. Cyst-formation only begins when healing commences,
never in the height of the disease. The encystment is preceded
by the rapid discharge of chromidia into the cytoplasm, and then
the nucleus degenerates and disappears. The chromidia then collect
to form a chromidial network in the ectoplasm, and subsequently
spherical bodies, the cysts, each surrounded by a yellowish-brown
membrane and containing a portion of the chromidial network, are
pinched off (Fig. 1 6, D). The rest of the life-history has not been
followed, but it has been shown that when the cysts are given to
cats they cause a dysenteric disease.
Other species of Endamoeba have been described from the human
intestines, but it is uncertain at present whether they are or are
1 The account given of Endamoeba coli and E. histolytica is mainly taken from
the important memoir of Schaudinn. This memoir is, however, not illustrated.
For further information and for figures of Endamoeba coli the reader is referred
to the memoir by Casagrandi and Barbagallo (38), and of E. histolytica to the
memoir of Jiirgens (39) and other papers mentioned in the list of literature on
p. 92.
THE LOBOSA
not associated with disease. Endamoeba undulans, Castellani (40),
exhibits a peculiar amoeboid form, which occasionally protrudes a
single pseudopodium. There is practically no distinction between
the ectoplasm and endoplasm. The presence of a peculiar undulat-
ing membrane running round one end of the body suggests that
the species may have different affinities to the ordinary species of
Endamoeba. 25-30 //,. Ceylon. Endamoeba iurai, Ijima (12), has
been described from the human intestines in Japan.
The species described under the name Parainoeba hominis by
Craig (41) was found in the faeces of patients suffering from
N
Fio. 16.
KiK/'Uiioeba histolytica, Schaudinn. A, B, two specimens from a case of dysentery in a cat ;
c, blood corpuscles being digested ; N, nucleus. (After Jiirgens.) C, specimen from human
intestine with resting nucleus (N) and a single non-contractile vacuole. D, specimen giving
rise by gemmation to a spore ; eh, chromatin of nucleus in the form of scattered chromidia ;
sp, protoplasm of spore containing some chromidia. (C and D after Lesage.)
severe diarrhoea in the Philippine Islands, associated with E.
histolytica and other Protozoa. There appear to be three phases in
the life - history : (1) an amoeboid phase, 15-25 p.; (2) a resting
cystic stage, 15-20 //,; (3) a biflagellate phase, 3-15/z. Notwith-
standing the general resemblance in its life-history to that of the
marine Paramoeba eilhardi, it is difficult to believe that this species
is rightly placed in the same genus.
Endamoeba blattae is often found in the rectum of the common
cockroach. In form it is similar to Amoeba Umax, but it seldom
pushes out a single pseudopodium and has remarkably clear proto-
plasm. It may be as much as 80 //, in diameter. Other species
probably belonging to the same genus are found in the intestines
.of mice and in the rectum of the frog.
84
THE LOS OS A
It is difficult to determine at present the true nature of many
of the amoeboid cells found in the pus and other fluids of patho-
logical conditions, but the following are regarded as parasitic
organisms : Amoeba urogenitalis, Amoeba kartulisi,
Amoeba buccalis.
Leydenia gemmipara is an amoeboid cell originally
found by Lieberkiihn in the ascites fluid of malignant
tumours. The endoplasm contains numerous fat
spherules, remnants of red and white corpuscles, and
numerous crystalline bodies. The most remarkable
feature of Leydenia, however, is the presence of a
definite contractile vacuole. Plastogamy frequently
occurs, and reproduction is effected by fission and
gemmation. There seems to be little doubt from
the researches of Schaudinn that Leydenia is an in-
dependent organism, but whether it should be placed
with tne LoDOsa or with the Myxomycetes is not
clear.
teria; c, at the an-
terior pole granules
are seen arranged in
the direction of the
protoplasmic cur-
rents (After schu-
Opm™
URDER
The body is protected by a shell or test, which
may be perforated by a hole — the pylome — or
widely open on one side like a cap. The test is not perforated by
the pseudopodia.
The test of the Thecamoebida is composed of two sheaths —
an inner sheath, which is in the form of a thin continuous layer ;
and an outer sheath, which is usually much thicker, and may be
strengthened by the secretion of definite hard plates or by the
adhesion of foreign materials of various kinds. The chemical
constitution of the test is difficult to determine with accuracy, but
it appears to consist of an organic matrix usually containing silica
in larger or smaller proportions. The inner sheath of the test
contains a small proportion or only traces of silica ; the plates and
prisms of the outer sheath, such as we find in Quadrula and its
allies, contain a much larger proportion of silica. The matrix
which cements the plates of Quadrula together, and which fastens
diatom shells, grains of sand, and other foreign bodies to the test of
Difflugia, is an organic substance which also contains a trace of
silica. In the plates of Quadrula irregularis calcium appears to
take the place of silicon.
There is no evidence of the occurrence of chitin in the tests of
any Thecamoebida, but a substance allied to keratin may occur in
some cases (Awerinzew [1]).
In the Cochliopodiidae the shell is thin and flexible. It is
usually marked by minute punctuations arranged in definite rows
or more irregularly distributed. When more highly magnified
THE LOBOSA 85
these punctuations appear to be globular in shape, but their precise
nature has not yet been determined.
In Quadrula the outer sheath consists of a series of square
plates cemented together by the matrix. These plates can be
raised to a high temperature without destruction of their form.
When boiled for a long time in 10 to 20 per cent KHO, they
are dissolved but leave behind a fine granular residue which
probably represents the inorganic components of the plates. In
Nebela the plates are discoidal, and in other genera irregular in form.
The diatom or desmid shells, the grains of sand or glass, and
other foreign bodies that are found fastened to the outer sheath of
the test of Difflugia (Fig. 20) and its allies are not adventitiously
placed, but are caught and definitely arranged in position by the
animal (Rhumbler). There can be little doubt that Difflugia exercises
a deliberate choice of the particles it uses for shell purposes, and
to a certain extent the character of the foreign particles and their
arrangement can be used for racial or specific distinctions.
In the Arcellidae the outer sheath is composed of hexagonal or
irregular prisms (Fig. 1 8), some of which, situated at regular
intervals, are rather longer than the others and
project on the surface as round knobs or bosses. QcOnxcnnnmj
The prisms are cemented together by an extremely FIG. is.
thin matrix. Section through the
The cytoplasm of the Thecamoebida is often BSSSttEB
arranged in three zones. The cytoplasm of the som.e of ^hich project
, , . -i i- -i • r i i . -it irregular intervals
pseudopodia and ot the region of the pylome is as shallow bosses on
usually remarkably hyaline and the granulations AwerinUzew?)'
extremely fine. In the middle zone it is more
coarsely granular, and contains the contractile vacuoles, food-
vacuoles, crystalline bodies, excreta, oil-globules, etc. In the zone
next to the fundus of the shell is usually found the nucleus or
nuclei and the sickle-shaped or more irregularly disposed chromidial
network. In the Arcellidae, however, the arrangement is somewhat
different from this (p. 86).
The pseudopodia are probably subject to considerable variation
in shape and number according to external conditions. In the
Difflugiidae there may be only one long finger-like pseudopodium
extended to a length double that of the shell, or there may be
three or four shorter pseudopodia, or occasionally as many as seven
protruded at the same time. In Heleopera the number of pseudo-
podia appears to be constantly more numerous than in other genera
of the family.
In some species of Arcellidae and Cochliopodiidae a membranous
expansion of the cytoplasm sometimes protrudes from the pylome.
Very little is known concerning the contractile vacuoles of the
Thecamoebida, as the thick opaque test interferes considerably with
86 THE LOBOSA
the observation of it in the living animal, but it seems probable that
one or more contractile vacuoles are present in all genera.
Nucleus. — For a considerable period in the life-history of Arcella
there are two large oval nuclei, from 0'015-0'02 mm. in diameter,
which are usually situated some distance apart, near the periphery
of the cytoplasm. More rarely three or even four of these
relatively large nuclei may be found. These nuclei are derived by
the karyokinetic division of the primary single nucleus of the young
Arcella. Each nucleus contains a single large ("008 mm.) nucleolus,
which apparently consists mainly of chromatin, but is otherwise
clear and transparent (Fig. 21).
In other Thecamoebida (Diffiugia1 and Centropyxis} there is
usually only one nucleus during the corresponding phase of the life-
history, and this exhibits a coarse reticulum of chromatin with
numerous nucleoli distributed through it.
The chromidial network of Arcella is in the form of an
irregular band or ring at the periphery of the cytoplasm, which
sends lobate processes or branches in the direction of the central
protoplasm. These processes are sometimes pinched off from the
peripheral ring, and appear as isolated patches of the chromidial
network in the central cytoplasm.
In Centropyxis the chromidial network is in the form of a thick
sickle-shaped band lying in contact with the convex aboral
extremity of the body. Sometimes this band envelops the
nucleus, but neither in Centropyxis nor in Arcella does the nucleus
come into contact with the network, being always surrounded by a
halo of clear protoplasm (Fig. 21). In some forms of Difflugia
the chromidial network is in contact with the nucleus (Fig. 6) ;
in D. globosa and others, however, there is a clear space between the
nucleus and the chromidial network as in Centropyxis, but in
these cases strands of the chromatin seem to .connect the nucleus
with the network.
In another phase of the life -history of Arcella there are
numerous nuclei. The number is very variable, from 5 to 39, but
in a great many cases there are about 25. These secondary nuclei
are formed by the concentration of granules of chromatin of the
chromidial network, which become rounded off and surrounded by
a nuclear membrane. The larger the number of nuclei, the smaller
they are. When very numerous these nuclei are not more than
0'009-0-01 mm. in diameter. As the secondary nuclei are formed,
the two or three primary nuclei degenerate and disappear.
When a certain number of secondary nuclei have been formed,
they divide by karyokinesis. This karyokinesis is a preparation for
the process of fission. One half of the nuclei resulting from the
karyokinetic division remain at the periphery, the remaining half
1 According to Zuelzer there are 10-30 nuclei in D. urceolata, Carter.
THE LOBOSA 87
migrate towards the centre of the protoplasm. It is probably this
central party of nuclei that, with their surrounding protoplasm,
protrude from the pylome of the shell and give rise to the daughter
Arcella in the process of fission.1
In Centropyxis (Schaudinn [27]) the formation of secondary
nuclei previous to fission does not occur. When fission is about to
take place, a considerable portion of the protoplasm protrudes from
the pylome, assumes the inverted form of the parent, and develops a
shell. The nucleus remains in that part of the protoplasm which
at this stage only half fills the shell of the parent Centropyxis. When
the daughter shell is formed the nucleus increases to nearly double
its former size, the nucleolus dwindles in size, and numerous minute
chromosomes are formed. These changes are followed by the
formation of a spindle, the arrangement of the chromosomes in an
equatorial plate, and subsequently by nuclear division. One of the
nuclei thus formed passes into the daughter individual and the other
remains in the parent.
While these changes in the nucleus are taking place, the
chromidial network divides into a great number of chromidia, which
collect round the two nuclei in equal proportions and pass with
them into the resultant individuals.
Encystment. — The formation of resting cysts occurs in Arcella,
Centropyxis, Nebela, Diffluyia, and probably in all the other
Thecamoebida (Martini [16]).
In Centropyxis, Schaudinn found that cj'sts are formed when
external conditions are unfavourable, such as in cases of desiccation,
scarcity of food, etc. In such cases the food particles, diatom
shells, excreta, a considerable proportion of the water, and any other
non-essential contents of the protoplasm, are ejected, while the
cytoplasm, with the contained chromidial network and nucleus,
contracts into a ball and is surrounded by a cyst- wall.
At the end of encystment the cyst - wall disintegrates, the
protoplasm swells up to its former size, and the normal processes
of life are continued. It does not seem probable in this case
that encystment has any connexion whatever with the sexual
process.
In Arcella, however, according to Hertwig (11), a reduction
in the number of the nuclei takes place, and it is suggested that
the process of conjugation may occur during this period of encyst-
ment, in a manner similar to that which occurs in Actinosphaerium.1
In Difflugia urceolata (Zuelzer [35]) a process of encystment occurs
in the late autumn, and is accompanied by a destruction of a great
many of the old nuclei. Before the cysts rupture in the spring the
contents break up into a number of uninucleate secondary cysts,
but the history of the secondary cysts has not been followed.
1 See Note, p. 93.
THE LOBOSA
Plastogamy. — A process of the temporary or permanent fusion
of two or more individuals has been observed by Schaudinn (27)
in Centropyxis, and by Zuelzer (35) in Diffiugia. urceolata, and probably
occurs in other Thecamoebida. In Centropyxis two individuals may
join together plastogamically and produce a daughter individual
with two nuclei and two chromidial networks, or if three individuals
join together they produce a daughter individual with three nuclei
and three chromidial networks. In some cases, the daughter
individual produced by the plastogamy has an abnormal shell and
the two nuclei and chromidial networks fuse together. In other
cases, again, only one of the individuals gives rise to a daughter
individual, and that is of the normal type.
In Difflugia urceolata a process of plastogamy occurs in which the
nuclei and chromidial networks remain passive, when external con-
ditions become unfavourable, but this appears to be antecedent only
to disintegration. In the autumn, however, the protoplasm of one
of the two participants in a plastogamic union passes into the shell
of the other, and more rarely a process of plastogamy occurs in which
the nuclei and chromidial network of both individuals are active, but
definite fusion of nuclear elements has not been observed. At the
end of this plastogamic fusion the empty shell may become firmly
fixed to the shell containing the fused individuals, giving rise to
the twin- shells so often found in cultures of these creatures
(Rhumbler [22]). The meaning of the different forms of plasto-
gamy in the Thecamoebida is not clear, but there is no evidence at
present that they represent any phase of the true sexual process.
The only observation of a true conjugation in the order is that
described by Schaudinn, in which
definite heterogametes are formed
and conjugate (p. 77).1
— -a,
Family COCHLIOPODIIDAE. Tests
usually thin and supple, with a
flexible margin, shaped like a cap,
limpet shell, or helmet. Pylome
widely open.
The genera included in this family
have close affinities with some of the
Gymnamoebida. The shell is not
perforated by the pseudopodia, but in
Cochliopodium it often assumes many
CoMiopodiun pellutidum, Hert. and different shapes according to the
Less, a, nucleus, surrounded by a halo of conditions of the animal, and in some
species usually attributed to the genus
(G. adinophorum and G. digitatum) it
entirely surrounds the body and is perforated by the pseudopodia, the
1 See Note,, p. 93.
Fia. 19.
Chr°midial
THE LOBOSA
89
apertures being closed again when the pseudopodia are withdrawn.
Cochliopodium, Hert. and Less., then, is the connecting-link between the
two orders. In Corycia, Dujardin, the test is supple and membranous, but
the pylome remains open. In Pseudochlamys, Clap, and Lach., the shell is
shaped like that of a limpet, but is very flexible, and the margin of the
pylome may in the retracted condition be inflected to form a shelf like
the velum of a medusa. In
Parmulina, Penard, the test is
in the shape of a cup or bowl.
In Hyalosphenia, Stein, the test
is rigid except at its margin.
Family DIFFLUGIIDAE.
Tests usually globular, or flask -
ehaped with a narrow pylome.
Outer sheath of the test with
hard plates, or with adherent
foreign particles, or with both.
Dijfluyia, Leclerc, is a genus
which exhibits a great many
varieties of form, some of which
are very common. The shell
is usually flask - shaped, and
consists of a tough double
membrane to which various
foreign bodies, such as diatom
shells, sponge spicules, sand-
grains, etc., are cemented. The
pseudopodia are rarely more
than two or three in number,
digitiform and blunt, but some-
times frayed at the extremities.
Some of the larger varieties are
over 0'5 mm. in length.
Centropyxis, Stein ( = Echi-
nopyxis, Clap, and Lach.), is
related to Difflugia, but the \J FIG. 20.
Bhell is usually discoidal Or Aj Diffiu{,ia pyrifwmis, Perty, with very large
oval, With the pvlome excentric diatom shells attached to the theca. B, test of
. . r _ . Quadrula symmetrica, Wallich. C, Lecquermsia
in position. It IS covered spiralis, Ehr. D, diagram of test of Pontigulasia
irre^ularlv with forpitm mr irlcisa> Rhumbler, showing the collar (co) and bridge
reign par- (b) E) vjew of the bridge (6) of Pmitiguiasia from
tides, and sometimes exhibits above. (A-C after Leidy ; D, B after Penard.)
two or three short spines.
Pontigulasia, Rhumbler, and Cucurbitella, Penard, are distinguished
by the presence of a short collarette round the pylome. In Pontigulasia
(Fig. 20, D and E) a broad flat bridge runs across the base of this collarette
and divides the pylome into two apertures. In Lecquemisia, Schlumberger
(Fig. 20, C), the shell is cornuate or slightly spirally twisted. The genera
Quadrula, Nebela, and Heleopera form shells with siliceous plates and are
not usually decorated at all with foreign particles. Quadrula, F. E.
90 THE LOB OS A
Schultze, is a common and widely distributed genus, with a shell of vari-
able shape, but distinguished by its regular pavement -like arrangement
of square or oblong plates (Fig. 20, B). Nebela, Leidy, is related to
Quadrula, but the plates of the shell are round, oval, or even irregular in
outline. In some species the shell is strengthened by adherent diatom
shells. In all species of this genus particles of "fat" of a pale blue or
yellow colour occur normally in the protoplasm. Similar particles also
occur in Difflugia and other genera, but are not so constant or characteristic
as they are in Nebela.
The shell of Heleopera, Leidy, is provided with square or oblong
plates as in Quadrula, but they are usually irregularly or untidily
arranged. The pseudopodia of this genus are more numerous than in
the others of the family, and are sometimes slightly branched.
In Phryganella, Penard, the shell is covered with adventitious particles,
as in Difflugia, but the pseudopodia are more numerous, more delicate,
frequently branched, and occasionally amalgamated at the base to form a-
membranous web. It appears to be related to Pseudodifflugia, Schlum-
berger, which is usually regarded as a member of the Order Gromiidear
of the Foraminifera. As it is quite impossible to draw a definite line of
distinction between organisms with a few fine blunt pseudopodia such as
are characteristic of the Difflugiidae and those with filamentous branching
pseudopodia such as are characteristic of the Gromiidea, there is a group
of genera occupying an intermediate position between the Rhizopoda and
the Foraminifera.
The principal genera of this group are :
Cryptodifflugia, Penard ; Pseudodifflugia,1 Schlumb. ; Diaphwodon,^
Archer ; Platoum,1 F. E. Schultze ; Clypeolina, Penard ; Nadinella, Penard;
Frenzelina, Penard ; Campascus,1 Leidy ; Cyphoderia,1 Schlumb.
Family ARCELLIDAE. Shells plano-convex in shape, marked by a
very fine hexagonal pattern, not supported
by adventitious particles.
Arcella, Ehr. This is a common and
widely distributed gemis. The shells of
the common species A. vulgaris vary from
80-140 p. in diameter, and like those v of
most of the species of Arcella are charac-
terised by their brown colour. The flattened
side of the shell is usually depressed and
perforated at the centre by the pylome,
FIO. 21. which is less than one-third the diameter
Arcella vulgaris, Ehr. a, shell ; of the shell. From the pylome there
b, protoplasm within the shell ; c, . ,-, f •, ' j • • , ,
lobose pseudopodia ; e, one of the project three or four, rarely more, digitate
marginal vacuoles ; d, d, nuclei sur- pseudopodia. Situated in the ectoplasm,
• rounded by a halo of clear proto- x . . . , .
plasm. (After Lankester.) and usually arranged in a circle round the
pylome, there is often seen a series of
vacuoles, which probably serve a hydrostatic function. They may fuse
together to form a single large excentric vacuole, and this may collapse
after the manner of a contractile vacuole.
1 Cf. Treatise on Zoology, Part I. Fasc. II. pp. 140-141.
THE LOB OS A 91
Arcella is common in bogs and stagnant water, but is occasionally
found in clear running water.
Pyxidicula, Ehr., differs from Arcella in having a large gaping pylome.
The surface of the shell is ornamented with numerous minute tubercles.
20-50 /*. The genus is comparatively rare and little known.
LITERATURE.
1. Awerinzcw, S. Die Structur und die chemische Zusammensetzung der
Gehause bei den Stisswasserrhizopoden. Arch. Prot. viii., 1906, p. 95.
2. Bott, K. Ueber die Fortpflanzung von Pclomyxa palustris. Arch. Prot.
viii., 1906, p. 120.
3. Bourne, A. (r. On Pelomyxa viridis n. sp. Q. J. Micr. Sci. xxxii., 1891,
p. 357.
4. Butschli, 0. Investigations on Microscopic Foams and on Protoplasm.
Translated by E. A. Miiichin. Black, 1894.
5. Untersuclmngen liber Structure!!. 1898.
6. Calkins, G. N. Marine Protozoa from "Woods Hole. U.S. Fish. Comm.
Bull. 1901, p. 413.
7. Evidences of a Sexual Cycle in the Life-History of Amoeba proteus.
Arch. Prot. v., 1904, p. 1.
8. Frenzel, J. Untersuchungen iiber die mikroskopische Fauna Argentiniens.
Arch. mikr. Anat. xxxviii., 1891, p. 1.
9. U^ber einige merkwiirdige Protozoen Argentiniens. Zeitschr. wiss.
Zool. liii., 1892, p. 334.
10. Goldschmidt, R. Die Chromidien bei Protozoen. Arch. Prot. v., 1904,
p. 126.
11. Hertwig, R. Ueber Encystirung und Kernvermehrung bei Arcella vulgaris.
Fest. Kupffer, 1899.
12. Ij-ima. New Rhizopod of Man. Annot. Zool. Jap. 1898, p. 85.
13. Jennings, If. S. Contributions to the Study of the Behaviour of the
Lower Organisms. Washington, 1904.
14. The Movements and Reactions of Amoeba. Biol. Centralbl. xxv.,
1905, p. 92.
15. Lei/den, E., and Schaudinn, F. Leydenia gemmipara. S.-B. Akad. Berlin,
vi., 1896.
16. Martini. N. Beobaclitungcn an Arcella vulgaris. Zeitschr. wiss. Zool.
Ixxix., 1905, p. 574.
17. Mesnil, Felix. Chromidies et questions connexes. Bull. Inst. Pasteur,
iii., 1905, p. 313.
18. Neresheimer, E. Ueber vegetative Kernveranderungen bei Amoeba. Arch.
Prot. vi., 1905, p. 147.
19. Penard, E. Faune rhizopodique du bassin de Leman. 1902.
20. Amibes a pellicule. Arch. Prot. vi., 1905, p. 296.
21. Potent, W. Leidy's genus Ouramoeba. Science, viii., 1898, p. 778.
22. Rhumbler, L. Beitrage zur Kenntniss der Rhizopoden. Zeitschr. wiss.
Zool. Hi., 1891 ; and same journal, Ixi., 1896.
23. Zur Theorie der Oberflacheiikriifte der Amoeben. Zeitschr. wiss.
Zool. Ixxxiii., 1905, p. 1.
92 LITERATURE OF THE LOBOSA
24. Schaudinn, F. Ueber die Theilung von Amoeba binucleata. S.-B. Ges.
Naturf. Berlin, 1895, p. 130.
25. Ueber den Zeugungskreis von Paramocba eilhardi. S.-B. Ak.
Berlin, 1896, p. 31.
26. Untersuchungen iiber den Generationswechsel von Trichosphaerium
sieboldi. Anhang z. d. Abh. Ak. Berlin, 1899.
27. Untersuchungen iiber die Fortpflanzung einiger Rhizopoden. Arb.
kais. Gesundheitsamte, xix., 1903, p. 547.
28. Neuere Forschungen iiber die Befruchtung bei Protozoen. Verb.
deutsch. Zool. Ges., 1905, p. 16.
29. Schcel, C. Beitrage zur Fortpflanzung der Amoeben. Fest. Kupffer, 1899,
p. 569.
30. Schubotz, H. Beitrage zur Kenntniss der Amoeba blattae und Amoeba
proteus. Arch. Prot. vi., 1905, p. 1.
31. Stole, A. Ueber die Teilung des Protoplasmus in mehrkernigen Zustande.
Arch. Entw. Mech. xix. p. 631.
32. Plasmodiogonie. Arch. Entw. Mech. xxi., 1905, p. 111.
33. Vahlkampf, E. Beitrage zur Biologic und Entwickelungsgeschichte von
Amoeba Umax. Arch. Prot. v., 1905, p. 167.
34. Veley, V. H. A Further Study of Pelomyxa. J. Linn. Soc. Zool. xxix.,
1905, p. 374.
35. Ziielzer, M. Beitrage zur Kenntniss von Difflugia urceolata, Carter.
Arch. Prot. iv., 1904, p. 240.
Some of the more important recent papers on the parasitic Amoebae and
Amoebiasis,
36. Schaudinn, F. (No. 27.)
This paper contains the most important but uniUustrated account of
the life-history of Endamocba coli and Endamoeba histolytica.
37. Schuberg, A. Die parasitische Amoben des menschlichen Darmes. Kritische
Uebersicht. Centrbl. Bakter. xiii., 1893, pp. 598, 654, and 701.
These papers contain a critical account of the literature of Amoebiasis
up to the year 1893.
38. Casagrandi, Q., and Barbagallo, B. Entamoeba hominis s. Amoeba coli,
Lbsch. Ann. d' Igiene sperimentale, v., 1897, fasc. i.
This paper contains a full account of Endamoeba coli and its occur-
rence.
39. Jilrgens. Zur Kenntniss der Darmamoben und der Amoben -Enteritis.
Verbff. a. d. Gebiete Militarsanitatswesens, 1902, Heft 20, p. 110.
This paper contains a good account of Endamoeba histolytica.
40. Castellani, A. Protozoa in Human Faeces. Centralbl. Bacter. xxxviii.,
1905, p. 66.
41. Craig, C. F. A New Intestinal Parasite of Man, Paramocba hominis.
Amer. J. Med. Sci. cxxxii., 1906, p. 214.
42. Dopter, C. Sur quelques points relatifs a Faction pathogene de 1'Amibe
dysenterique. Ann. Inst. Pasteur, xix., 1905, p. 417.
43. Lesage, A. Culture de 1'Amibe de la dysenteric des pays chauds. Ann.
Inst. Pasteiir, xix., 1905, p. 9.
LITERATURE OF THE LOBOSA 93
44. Mugliston, T. C., and Freer, G. D. An Undescribed Form of Ulceration of
the Large Intestine, probably of Amoebic Origin. J. Trop. Medicine, viii.,
1905, p. 113.
45. Afusgrave, W. E., and Clegg, M. J. Amoebas : their Cultivation and
Etiological Significance. J. Inf. Diseases, ii., 1905, p. 334, and Publ.
Bureau Govt. Lab. Manila, xviii., 1905, p. 5.
References to the general treatises of Butschli, Braun, Calkins, Cash, Doflein,
Jfartog, and Lang will be found on p. 13.
NOTE. — In a recent paper W. Elpatiewsky (Arch. Prot. x., 1907, p. 441) has
shown that Arcella produces small amoeboid gametes (megamoebae and micra-
moebae) which conjugate and form a zygote.
THE PEOTOZOA (continued)
SECTION E. THE RADIOLARIA 1
THE Eadiolaria are purely marine Gymnomyxa, specialised for
pelagic life. The body is usually spherical or conical, and emits
radiating thread-like pseudopodia. The cytoplasm is subdivided
by a perforated membranous " central capsule " into a central mass
and a voluminous mantle. The nucleus, which may be single or
multiple, is confined to the intracapsular region, which is also the
seat of reproductive changes, the extracapsular mantle being con-
cerned with flotation, feeding, stimulation, and excretion. A siliceous
skeleton is usually present, and may take the form of spicules,
shells, and tubes in a variety of delicate and exquisite constructions.
In one division (Acantharia) the skeleton consists, so far as is known,
of strontium sulphate. In most Radiolaria peculiar nucleated yellow
corpuscles are found in abundance. They are regarded either as
" symbiotic algae " or as Peridinians. Multiplication by fission is
known in a few cases ; more commonly reproduction by spore-
formation has been observed.
DESCRIPTION or THALASSICOLLA.
As an introduction to the description of the class the following
account of Thalassicolla has been drawn up.
Thalassicolla is a spherical gelatinous Protozoon from 3-5 mm.
in diameter. In the warmer waters of the great oceans it occurs in
vast swarms that float passively at the surface but also descend
into deeper water during the reproductive phase. It ranges for some
forty degrees of latitude on either side of the equator, diminishing
in numbers towards these limits. It is abundant in the Faroe
Channel (Wolfenden, Fowler), and a stray specimen is now and
then recorded from our coasts (Delap [40]).
Thalassicolla consists of two parts — a central or medullary region
and a thick outer or cortical layer. The two are separated by the
central capsule.
The intracapsular mass consists of a large centrally placed
nucleus embedded in cytoplasm, heavily laden with concretions,
1 By F. W. Gamble, D.Sc., F.R.S., Manchester University.
94
THE RADIOLAR1A
95
coloured fat, and reserve products. The extracapsular cytoplasm
is composed of — (1) a thin, black, fatty assimilative layer or matrix
immediately outside the central capsule ; (2) a frothy mass of
mucilaginous and vacuolated substanpes secreted by interstitial
cytoplasm and forming the so-called "calymma" ; and (3) of fine
radiating pseudopodia which arise from the matrix and extend
freely into the water beyond the gelatinous bubbly layer. The
wall of the central capsule is perforated by minute, evenly dis-
EP
d
FIG. 1.
Thalassicolla (Thalassophysa) pelagica, Haeckel. x 25. CK, central capsule ; EP, extra-
capsular protoplasm ; al, alveoli, carbonic acid-holding vacuoles in the mucilaginous calymma
secreted by the protoplasmic network ; ps, pseudopodia. The minute unlettered dots are the
" yellow cells." (After Lankester.)
tributed pores, and through these the intra- and extracapsular
cytoplasm are continuous.
If the central capsule is shaken out of its calymmal covering
and kept under suitable conditions, its contents are capable of
regenerating the extracapsular cytoplasm within a week (Verworn
[14:]). The first sign of this process is the protrusion of new radial
pseudopodia, which are completed in twelve hours. The basal
ends of these processes form or secrete a layer — the matrix — that
invests the central capsule, and their radial extensions secrete the
calymma. Finally, vacuoles make their appearance in the jelly
and the matrix becomes pigmented. In short, the extracapsular
96 THE RADIOLARIA
protoplasm and its secretions are the product of intracapsular
activity. The extracapsular cytoplasm, on the other hand, has
no such regenerative power. When detached from the capsule it
loses its form, the pseudopodia contract, the vacuoles burst, and
the plasma undergoes granular degeneration. For this and other
reasons we may speak of the extracapsular cytoplasm as the ecto-
plasm, and the intracapsular plasma as the endoplasm ; for although
the pseudopodia are common to both and interconnect them, yet
the mass of the calymma is a secretion specialised for contact with
the outer world, and performs other important functions, whilst the
endoplasm is less directly concerned with the immediate physiological
needs of the animal.
Bionomics. — The most remarkable physiological characteristic
of Thalassicolla is its paucity of reaction. It possesses no power
of active movement, and responds only to two forms of external
stimulus — vibration and heat ; and to one internal agency, namely,
the stimulus of reproduction. Under the influence of wave-action
Thalassicolla sinks till a calm stratum is reached, and then after a
time ascends to the surface. Towards small variations of temperature
it remains as inert as toward all conditions of illumination that
have so far been tried ; but a long-continued application of tempera-
tures above 30° C. or below 2° C. induces a descent from the
surface of the sea-water, and this is followed by the death of the
animal. The onset of maturity is also correlated with a descent
into deep water. During the nutritive phase and under normal
variations of vibration, heat, and light, the station of TJialassicolla is
at or near the surface of the sea.
This station is ensured for it by the development of the calymma.
The mass of this veil is made up of a mucilaginous secretion containing
fluid-vacuoles, and is enclosed in a delicate cytoplasmic investment,
the quantitative proportion of which is in minimal relation to the
bulk of its secretions and vacuolar fluid. By careful observation,
weighings, and experiment, Brandt (24) has shown that the vertical
movement of Thalassicolla is due to the formation and expulsion
of vacuolar fluid. The hydrostatical requirements of the case
demand that, for flotation at the surface, the density of this fluid
should be that of water saturated with carbonic acid. As the
physiological probability is in favour of this conclusion, we may
accept Brandt's view as in all likelihood correct. Assuming
this, then, the explanation of passive descent and ascent is easy.
In calm weather and through a considerable range of temperature
the interchange of fluid between the vacuole and the sea is gradual,
and the slight wave-motion reinforces the calymma by acting as a
stimulant. Thus we may assume the balance of loss and gain, and
with it the surface position, are maintained. But the movements
of larger or more frequent waves, or the extremes of experimental
THE RADIOLARIA 97
temperature, cause contraction of the calymmal plasma. The pseudo-
podia are withdrawn, the vacuoles burst, and the animal descends
until the calmer zone enables it to reform its calymma and recharge
its vacuoles, upon which it ascends. No " contractile vacuoles "
are present, but their place is taken by these fluid-spaces in the
calymma.
Food. — The food of Thalassicolla consists of Copepods, Diatoms,
Infusoria, and probably also of Peridiniae. These organisms adhere
to the surface of the Kadiolaria by contact with its sticky pseudo-
podia. They are subsequently enfolded by a plasmic web and
carried into the deeper part of the calymma. Here a digestive
vacuole is formed, and the ingested organism becomes converted
into a granular mass, which is disseminated, by division of the
digestive vacuole, throughout the ectoplasm. An accumulation of
debris may sometimes be found in the denser layer enveloping
the central capsule, and there is little doubt that the products of
digestion do not stop here but are carried into the endoplasm, for it
is known that a streaming movement occurs along the pseudopodia
that connect the inner and outer cytoplasm through pores in
the capsular wall. Once inside the capsule, the food material is
probably synthesised into the fatty or proteid masses that con-
stitute reserves. The endoplasmic globules of fat are usually
coloured with a pigment that varies according to the species of
Thalassicolla under consideration. The other reserves take a con-
cretionary form and recall starch grains in their stratified composi-
tion, though not in their reactions. They lie in vacuoles filled
with a proteid, and are still imperfectly known (Fig. 2, A, Cone.).
Yellow Cells. — The ingestion of solid food is, however, not
essential to the life of Thalassicolla for at least several months. If
kept in water that has been taken from the open sea and com-
pletely filtered, Thalassicolla will live for at least six months without
showing retrogressive changes beyond a shrinkage of calymmal
volume. Brandt, who has carried out experimental studies on
these organisms for many years, states (24) that if comparable
batches are maintained in such filtered water in darkness and in
light, the illuminated ones alone survive. He infers that Thalas-
sicolla under these conditions lives upon food which is in some way
elaborated under the influence of light ; and in point of fact such
a substance — starch — does exist in the ectoplasm. It occurs both
free in the capsular layer and imbedded in the substance of certain
corpuscles which are scattered through the calymma and are
known as the " yellow cells." The significance of these cells or
" zooxanthellae " is, in Brandt's view, a nutritive one.
That these bodies are independent organisms living in association
with Thalassicolla and are not part of it was proved by Cienkowski (6).
They are spherical structures '015 mm. in diameter, and consist of
7
98 THE RADIOLARIA
a cellulose wall, two chloroplasts marked by diatomin or an allied
pigment, a pyrenoid, starch of hollow and solid varieties, and a
nucleus. During the life of their host the zooxanthellae multiply
by transverse fission. After its death they pass into a "palmella
state " characterised by a mucilaginous jelly, and from this they
often escape as active biflagellated zoospores.
Such zooxanthellae are frequent though not constantly present
in Thalassicolla. In T. nudeata they may be plentiful, scarce, or
absent. In most species they occur unfailingly ; sometimes in the
outermost jelly, sometimes in radial masses throughout the calymma,
or aggregated round the capsule, but never within it. The adapta-
tion of their host to surface life meets the requirements of the
yellow cells for light, oxygen, and no doubt other unascertained
demands, with the result that the association has been regarded as
one of mutual advantage, as a case of symbiosis.
The more recent work of Famintzin (13) has, however, tended
to diminish the importance of the part which, according to Brandt,
is played by the abundant starch of the yellow cells in nourishing
their host. According to the later writer, the nutrition of Thalassi-
colla is mainly derived from ingested organisms, and is only aided
by the yellow cells in as far as these bodies are digested by the
ectoplasm. It is probable, though exact demonstration is as yet
wanting, that in some diffusible state exchange of material does take
place from zooxanthella to host without involving the death and
digestion of the former. Such a relation, however, does not explain
the presence of the yellow cells in Radiolaria.1
Respiration. — The researches of Vernon (22) have shown that
gelatinous or mucilaginous pelagic animals have a high rate of
destructive metabolism, and that the amount of oxygen absorbed
per unit of dry body -weight is further increased in the smaller
animals as compared with the larger members of the same group,
and in those of warmer seas as against their cold-water relatives.
The maximum relative absorption of oxygen amongst inverte-
brate planktonic animals is reached, according to Vernon, in the
Radiolaria. Collozoum, a near ally of Thalassicolla, has the highest
coefficient of all invertebrates, equivalent to forty times that of
the frog ; and although it is desirable to have further evidence
before accepting this startlingly high figure, yet the evidence of other
pelagic forms points unmistakably to a very large consumption of
oxygen.
The recent work of Putter (43) has emphasised the singular
nature of Protozoon respiration. It has long been known that
many of these organisms can live for a time as anaerobes, and it
now appears that intramolecular respiration obtains in a great
number of cases and to an unexpected extent. Fresh energy is set
1 For a discussion of the origin of the association see below, p. 129.
THE RADIOLARIA 99
free during the decomposition of reserve materials, and so long as
the waste products evolved in this process are removed, respira-
tion will continue in a medium deprived of free oxygen. Such a
view enables us to consider the reserve materials of Radiolaria
as of respiratory as well as of nutritive significance. It is not
improbable that the respiration of the endoplasm (in which these
fatty and stratified reserves occur) is of a different character from
the more violent exchange which seems to occur in the ectoplasm.
In connection with destructive metabolism we may summarise
our view on the nature of excretory processes in Thalassicolla. That
carbonic acid and nitrogenous excreta are formed in abundance
seems certain from the rapid destruction and regeneration of the
calymma and its vacuoles, but there is no accumulation of excretory
substances such as occur in most Rhizopods. It is suggested, on
the basis of experiments with Turbellaria (Gamble and Keeble [41]),
that this absence of excretory matter is due to the activity of the
yellow cells, which are attracted to their host chemotactically and
from which, by the uric acid or urea therein, they derive their nitrogen.
In the same way such a view affords an explanation of the associa-
tion of zooxanthellae with Radiolaria, and of the apparently con-
comitant absence of excretory granules. Additional proof of the
correctness of this view lies in the fact that such granules occur
massively and constantly in one division of the Radiolaria (the
Phaeodaria or Tripylaria), and that in this division, and in this
only, zooxanthellae are as constantly absent.
Reproduction. — In addition to multiplication by simple fission
(25a), Thalassicolla has two true reproductive processes, which, how-
ever, never occur in the same individual. These processes con-
cern the formation of spores, which are of two kinds, isospores
And heterospores. A given Thalassicolla is, therefore, isosporous or
heterosporous.
When the reproductive period ensues, the protoplasm and its
contents undergo a metamorphosis, which results in the transforma-
tion of the endoplasm into a mass of flagellated spores, in the dis-
integration of the calymma, and the separation of the sporulating
capsule from its envelope. The relatively heavy capsule descends
to a depth of 300-400 metres, its wall bursts, and its spores are
liberated. In the case of isospores these bodies are of uniform
shape and size (Fig. 2, D) ; in the case of heterospores (L, M) two
varieties occur, of which the larger are not only twice the size of
the smaller ones, but possess other distinctive characters which are
given below.
The formation of isospores in Thalassicolla nucleata proceeds as
follows (Brandt [26]). The nucleus and endoplasm undergo a
series of changes. The chromatin, previously coiled up in a thick
thread, becomes evenly granular, and the nucleoplasm acquires an
almost homogeneous and doubly refractive character, and becomes
irregular in shape as its membrane disappears. By what appears
to be amitotic division the nucleus fragments into a large number
of equivalent pieces, each of which behaves as an independent
nucleus, and by further division these nuclei become disseminated
through the endoplasm. Around each nucleus the cytoplasm con-
denses to form an ovoid mass, which is differentiated at the nuclear
pole into two cilia. Meantime the reserve materials of the endo-
plasm become subdivided and apportioned, so that each isospore
contains a few granules of fat and a crystalloid. These changes
may be followed on the accompanying figures (Fig. 2, A-D).
The development of heterospores in Thalassicolla proceeds in a
different manner and from distinct individuals. The first step is
the formation of a nuclear figure. A clear achromatic vesicle
(centrosome, Brandt, 1905) arises in the nucleus and becomes
surrounded by granular radiations, upon which the thick bent
chromatin threads arrange themselves as in Fig. 2, E. The centro-
some now shifts towards the margin of the nucleus, and the more
peripheral chromosomes become lumpy and slightly vacuolated.
The nuclear wall softens, and through it, at one pole, pass the
centrosome and a few apical chromatin granules. Subsequently the
nuclear sap escapes over the entire periphery of the nucleus,
together with much of the granular nuclear matrix, into the sur-
rounding endoplasm. The chromatin threads fragment and the
fragments become associated with segregated masses of fine nuclear
granules to form organised nuclei, Avhich divide mitotically. During
this process the nuclei are carried outwards in increasing numbers
towards the wall of the central capsule, where they become
arranged in columns, until almost the whole of the original nucleo-
plasm is used up. The most remarkable features of this organising
process is that the developing nuclei are of two sizes, which are
severally aggregated in the peripheral columns. Meantime the
endoplasm and its reserves have been mobilised. The former is
converted into cylinders around the mega- or micro-nuclei, and
within these cylinders the fat and crystalloids become fragmented
and distributed. Finally, by subdivision of these nucleated masses
colonies of mega- and micro-spores arise. Both are biciliate, and in
comparison with isospores minute, and divided by a groove into a
reniform shape. The microspores are from O'OOS to O'Ol mm. in
length, the megaspores O'Ol 6 to O'Ol 7. The microspores have a
deeply staining granular nucleus and a cytoplasm free from inclu-
sions except for one or two minute crystalloids. The megaspores,
on the other hand, possess a nucleus poor in chromatin, and their
cytoplasm is crowded with refringent corpuscles. Both forms of
heterospore have the same ciliary mechanism (Fig. 2, L). From
one point in the groove two long cilia arise, one of which works
M.
FIG. 2.
The development of isopores and heterospores in Thalassicolla nudeata. (After Brandt, 1905.)
A-C, isospore-fonnation, xlOO. The large nucleus (N) breaking up into spore nuclei (N. Isp).
1), an isospore (x 2000); Cone, stratified concretions lying in proteid vacuoles. E-K, hetero-
spore - formation, x 100. E, nuclear membrane collapsing. Nuclear figure and one intra-
nuclear centrosome. F, diffusion of nucleoplasm (A'w) outwards. G, organisation of second-
ary nuclei (Ao). H and K, segregation of these nuclei to form heterospore nuclei. L, mega-
spores. This figure shows the two flagella arranged like those of a Dinoflagellate. M, micro-
spores. L, M, x 1000.
101
102 THE RADIOLARIA
horizontally and is coiled round the body of the spore, the other
projects freely outwards and backwards. Consequently, as these
minute structures dart or vibrate, they rotate unceasingly about
their long axis, the whole mechanism and display recalling those
of certain Peridiniae.
The further history of the iso- and heterospores is unknown.
Brandt's recent attempts (26) to obtain conjugation between spores
of the same and of different individuals have been as futile as those
of earlier observers. If, however, we may judge by the analogy of
other Protozoa, and in particular by the life -history of Tricho-
sphaerium (Schaudinn [42]), we may presume that the heterospores
are male and female gametes, and that the isospores are asexual indi-
viduals. But on this question, as on the further one of a suggested
alternation between isosporous and heterosporous generations of
Thalassicolla, we still lack information.
1, central capsule of Thalassicolla nucleata, Huxley, in radial section, x 100 ; a, the
large nucleus (Binnenblaschen) ; 6, proteid vacuoles of the intracapsular protoplasm con-
taining concretions ; c, wall of the capsule (membranous shell), showing the fine radial pore-
canals ; d, chromatin substance of the nucleus. 2, 3, Collozoum inerme, J. Miiller, two different
forms of colonies, of the natural size. 4, central capsule from a colony of Collozoum inerme,
showing the intracapsular protoplasm and nuclei, broken up into a number of isospores, each
of which encloses a crystal of strontium sulphate ; c, yellow cells lying in the extracap.sular
protoplasm. 5, a small colony of Collozoum inerme, magnified 25 diameters ; a, alveoli
(vacuoles) of the extracapsular protoplasm ; b, central capsules, each containing besides proto-
plasm a large oil-globule. 6-13, yellow cells of various Radiolaria. 6, normal yellow cell ;
7, 8, division with formation of transverse septum ; 9, a modified condition according to
Brandt; 10, division of a yellow cell into four; 11, amoeboid condition of a yellow cell from
the body of a dead 'Sphaerozoon ; 12, a similar cell in process of division ; 13, a yellow cell the
protoplasm of which is creeping out of its cellulose envelope. 14, Heliosphaera inermis, Haeck.,
living example, X400; a, nucleus; 6, central capsule; c, siliceous basket-work skeleton.
15, two isospores of Collozoum inerme, set free from such a central capsule as that drawn in 4;
each contains a crystal 6 and a nucleus a. 16, two heterospores of Collozoum inerme, of the
second kind, viz. devoid of crystals ; and of two sizes, a megaspore and a microspore. They
have been set free from central capsules with contents of a different appearance from that
drawn in 4. o, nucleus. 17, Actinomma asteracanthion, Haeck., x260 ; one of the Peripylaria.
Entire animal in optical section, o, nucleus ; b, wall of the central capsule ; innermost siliceous
shell enclosed in the nucleus ; c1, middle shell lying within the central capsule ; c2, outer shell
lying in the extracapsular protoplasm. Four radial siliceous spines, holding the three spherical
shells together, are seen. The radial fibrillation of the protoplasm and the fine extracapsular
pseudoppdia are to be noted. IS, Amphilonche messanensis, Haeck., x 200; one of the Acan-
thometrida. Entire animal as seen living. (After Lankester.)
CHIEF MODIFICATIONS OF STRUCTURE IN THE RADIOLARIA.
The Radiolaria may be derived from such an organism as
Thalassicolla by — (1) fission and the formation of a colony of similar
or dimorphic individuals imbedded in a voluminous communal jelly
(Sphaerozoa or polyzoic Radiolaria) ; (2) by differentiation of the
openings of the central capsule from its evenly porose condition
(Peripylaria) to a radially segregated oligo-porose type (Acantharia),
to a single pore-plate at one pole of the now asymmetrical capsule
(Monopylaria), or to a single main aperture and two lateral ones
(Tripylaria) ; (3) by differentiation in the ectoplasm of skeletal
spicules and shells of the most diverse forms, which only in the
Acantharia invade the endoplasm.
104 THE RADIOLARIA
Amongst the most primitive Radiolaria are the Physematiidae
and the allied families Thalassicollidae, Thalassophysidae, etc. In
all these forms the hydrostatic jelly is so well developed as to give
the term Collodaria to the order formed by them. In the first
family, however, the vacuoles elsewhere found in the ectoplasm are
endoplastic products, no stratified nutritive concretions are found,
and yellow cells are absent. The skeleton, if present, consists
merely of scattered spicules. These organisms belong to the
surface strata of the ocean and are phosphorescent. Their life-
history falls into well-marked nutritive and reproductive phases.
The early nutritive stage was erected by Haeckel into a special
genus Actissa, which Brandt has shown to be a phase of growth
that occurs in at least two of the five families. The later nutritive
stage differs in few characters from that of Thalassicolla. The Phy-
sematiidae afterwards pass into an isosporous reproductive phase ;
FIG. 4.
1, Lithocircus annularis, Hertwig ; one of the Monopylaria. Whole animal in the living
state (optical section), a, nucleus ; 6, wall of the central capsule ; c, yellow cells ; d, per-
forated area of the central capsule (Monopylaria). 2, Cistidium ine.rme, Hertwig ; one of
the Monopylaria. Living animal. An example of a Monopylarion destitute of skeleton, a,
nucleus ; b, capsule wall ; c, yellow cells in the extracapsular protoplasm. 3, Carpocanium
diadema, Haeck. ; optical section of the beehive-shaped shell to show the form and position of
the protoplasmic body, a, the tri-lobed nucleus ; b, the siliceous shell ; c, oil-globules ; d, the
perforate area (pore-plate) of the central capsule. 4, Coelodendron gracillimum, Haeck. ; living
animal, complete ; one of the Tripylaria. a, the characteristic dark pigment (phaeodium)
surrounding the central capsule b. The peculiar branched siliceous skeleton, consisting of
hollow fibres, and the expanded pseudopodia are seen. 5, central capsule of one of the
Tripylaria, isolated, showing a, the nucleus ; 6, c, the inner and the outer laminae of the
capsule wall ; d, the chief or polar aperture ; e, e, the two secondary apertures. 6, 7, Acan-
thometron Claparedei, Haeck. 7 shows the animal in optical section, so as to exhibit the
characteristic meeting of the spines at the central point as in all Acanthometrida ; a, small
nuclei ; b, a parasite (Amoebophrya) ; c, wall of the central capsule ; d, extracapsular jelly ;
e, peculiar intracapsular yellow cells. 8, Spongosplinera streptacantha, Haeck. ; one of the
Peripylaria. Siliceous skeleton not quite completely drawn on the right side, a, the spherical
extracapsular shell (compare Fig. 3 (17)), supporting very large radial spines which are con-
nected by a spongy network of siliceous fibres. 9. Aulosplutera degantissima, Haeck. ; one
of the Phaeodaria. Half of the spherical siliceous skeleton. (After Lankester.)
the Thalassicollidae into either isosporous or heterosporous modes
of reproduction ; and the Thalassophysidae fragment suddenly into
hundreds of minute pieces (see pp. 137-8), without passing, so far as
is known, into a sporulating phase.
In the next division (Sphaerozoa) the polyzoic condition is
characteristic of the nutritive phase. The colony or coenobium is
spherical, elongate, or moniliform, though the individuals may
retain the primitive homaxonic symmetry (Collosphaeridae) or
become flattened (Sphaerozoidae). The skeleton may be absent,
spicular, or spheroidal, and the scattered " nuclei " are homogeneous
lumps of chromatin.
The life-history of the Sphaerozoa is still incompletely known,
though much has been done by Brandt (1885) to follow it. Accord-
ing to this writer three kinds of sexual individuals or colonies
occur : — isosporous forms, heterosporous forms produced directly,
and heterosporous forms produced after gemmation. In the Sphaero-
106 THE RADIOLARIA
zoidae both megaspores and microspores arise in the same individual j
isospores in different individuals. Moreover, the asexual individuals
are not all alike, but in certain genera at least some produce extra-
capsular bodies (pp. 138-9), and those individuals which bud off these
structures are, according to Brandt, young forms. These fertile
young forms become in many cases heterosporous — the extra-
capsular body forming the megaspores, the intracapsulum giving
rise to the microspores — but in other cases the extracapsiilar bud
develops into a new central capsule. Consequently we have two
forms of heterosporous individuals and one isosporous form, and
Brandt suggests that there is an alternation between the hetero-
sporous and homosporous individuals. Famintzin, however, has
reinvestigated the matter, and finds, in the vast numbers of full-
grown colonies that occur in autumn at Naples, some are converted
into isospores, some into heterospores, and many have extracapsular
bodies. These last colonies divide into small winter ones, the
majority of which possess extracapsular buds and develop into
heterosporous forms. According to Famintzin there is no alter-
nation of generations (13).
Whilst the Sphaerozoidae thus either become heterosporous
directly, or indirectly after division and the development of extra-
capsular bodies, the Collosphaeridae have no extracapsular buds,
and their mega- and microspores develop in separate individuals.
The skeleton when present takes the form of a perforated shell,
but notwithstanding these differences they are held to be rightly
separated from the Sphaerellaria, with which Haeckel formerly
united them.
The Sphaerellaria include an immense number of solitary
chambered forms, the majority of which are spherical, the remainder
being elliptical or flattened. Eadial bars unite the chambers, but
these bars are wholly ectoplasmic, and are never joined at the centre
of the endoplasm as in certain Acantharia. The nucleus remains-
single, but grows with the growth of the individual.
The Acantharia form a primitive group of Eadiolaria with many
interesting distinctive features. They retain homaxonic symmetry,
but the pores of the central capsule are less closely set than in the
Spumellaria. Through these pores there pass not only the cyto-
plasmic bridges between ectoplasm and endoplasm, but also two-
other radiating structures, namely, stiff pseudopodia (axopodia) and
spicules. The latter meet in the centre of the capsule (Fig. 4 (7)),
the former surround the centre and alternate with the spicules
(Fig. 18), which pass outwards generally in five whorls. These
emerge from the ectoplasmic surface at points through which five
circles could be inscribed corresponding to the two tropical, two
polar, and equatorial lines of the globe.
The whole disposition strongly suggests that the radiating
THE RADIOLARIA
107
spicules have developed by a hardening of the stiff fibre of certain
alternate axopodia which formerly met at the centre of the endo-
plasm as in Heliozoa, to which group this order suggests other
points of affinity. The peculiar nature of these spicules is the
distinguishing feature of the order. They are composed, in the
best investigated cases, of strontium sulphate (Biitschli, 1906), and
not of a chitinoid organic acanthin-substance, as Haeckel supposed.
Fio. 5.
To illustrate the structure of the
Nassellarian sub-family. A, Plagonis-
cu,s tripodiscus, II., showing the central
capsule (c.c) supported by the skeletal
tripod. B, Cortina typus, H., showing
the tripod and sagittal ring (5) enclos-
ing the central capsule, within which
are seen the podocone (p), the nucleus
above, and three oil -globules. C, Tre-
pospyris cortiniscvs, H., to show the
formation of the helmet-like type of
skeleton from the tripod and sagittal
ring. (After Haeckel. )
The nucleus is a multiple structure, and the large body frequently
mistaken for a nucleus (Fig. 4 (6, &)) is a Suctorian parasite. The
Acantharia frequent the upper layers of the ocean (chiefly from
the surface down to 300 metres), and are abundant in Arctic and
Antarctic seas as well as in the intermediate zones. The yellow
cells that in other Radiolaria are confined to the extracapsulum,
occur almost exclusively within the central capsule in the
Acantharia.
The Monopylaria or Nassellaria include an immense range of
forms. In the simplest the central capsule is supported by a
siliceous tripod or tetrad spicule, often accompanied by a sagittal ring.
io8
THE RADIOLARIA
It contains a peculiar cone of doubtful significance (Fig. 5, B, p).
The ectoplasm streams out from the capsular pore-plate and forms a
dense bubbly mass around this opening. From this point it passes
as a thin layer around the capsule, so that the cytoplasm is asym-
metrically distributed. These Radiolaria are, in fact, bilaterally
symmetrical. Lateral outgrowths from the spicule or sagittal ring
give rise to a helmet-like shell or "cephalis," in the upper part
Eucyrtidium cranioides, Haeck., x 150; one of the Monopylaria. Entire animal a.s seen in
the living condition. The central capsule is hidden by the beehive-shaped siliceous shell
withinlwhich it is lodged.
of which the central capsule is lodged. The cephalis becomes
voluminous and often constricted, producing a vast array of specific,
skeletal variety, the whole of which is produced by modification of
a single spicule. The nucleus, though often lobed, remains single.
Spore-formation is known to occur, but no form of reproduction has
been adequately investigated. The bionomics of the group are
quite unknown.
The Tripylaria or Phaeodaria form another large group, most
THE RADIOLARIA
109
easily characterised by the brown, greenish-brown, or black accumu-
lation of food material, debris, and resistant " phaeodellae " that lie
in the oral half of its ectoplasm ; and they are also signalised by
the mode of distribution of the capsular pores. In the majority of
genera the endoplasm communicates with the ectoplasm only by
a teat-like operculum and a pair of small lateral conical pores
(the so-called astropyle and parapyles). In a few cases two
astropyles occur, and in at least one genus (Atlanticella) only a
single pore-plate is present. The skeleton varies greatly in structure
A--
S^ Pfi
Fio. 7.
Aulactiniuin actinastrum, H. ; a member of the Phapodaria. (After Haeckel, slightly
modified.) A, astropyle ; C, calymma ; AT, double nucleus lying in the endoplasm ; P,
parapyle ; PJi, phaeodium.
and configuration. It is usually of a tubular nature, and the hollow
cylinders are often subdivided by septa. The basis of these
tubes, however, is formed by minute aciculate spicules which are
surrounded by a gelatinous sheath, and between this sheath and
the surrounding ectoplasmic matrix is a thin membrane, which first
becomes silicified. This is followed by deposition of silica in the
gelatinous sheath, and in this way complex spicules, often with
candelabra-like appendages, are developed. A single or double per-
forated shell may be present, the surface of which has a peculiar
porcellanous appearance and " diatomaceous " structure. In the
no THE RADIOLARIA
most complex Phaeodaria this shell acquires a bivalvular form and
carries many peculiar processes (Fig. 32).
The nucleus is a large, usually single structure, and undergoes
a peculiar kind of mitosis accompanied by the formation of a great
number of chromosomes. The development and nature of the
spores is incompletely known. A characteristic feature of this
order is the absence of the yellow cells that occur almost constantly
in the other orders. This negative feature appears to be correlated
with the presence of that remarkable and still imperfectly analysed
complex, the phaeodium. The researches of Borgert (18) give
some ground for thinking that the phaeodellae (see p. 119) are
excreta, and if so, the retention of these substances in Radiolaria
devoid of " yellow cells " lends support to the view, derived from
a study of the Turbellaria (Keeble and Gamble [41]), that these
symbiotic algae exert a depuratory function.
Variation: Dimorphism. — The Radiolaria present three kinds
of structural modification. There is the divergent variation about
one or more centres that constitutes a " species." There is racial
somatic dimorphism in relation to pelagic or abyssal life. And
there is gametic dimorphism both in early and adult stages of life
in relation to reproduction.
The conception of " species " in Radiolaria is only gradually
assuming a form similar to that held in the case of other Protozoa.
Hitherto skeletal characters have been mainly and rigidly employed
for the erection of a vast number of specific forms. The larger
collections made by Plankton expeditions of recent years have
shown that many of these earlier species, and even genera, are
either growth stages of one and the same form, fission products
common to several species, or divergent variations referable to a
central " type." The first kind of variation probably occurs in
every Radiolarian and has been recently worked out for several
Tripylaria (Immermann). In Aulokleptes flosculus, for example,
spicules of three kinds can be met with, each one of which was the
basis of a separate species in Haeckel's classification. It has been
shown, however, by Immermann that the spicules pass through two
or more forms before arriving at their definitive stage, and may be
arrested at an intermediate stage. Further knowledge of the
development of the skeleton will undoubtedly tend to diminish the
profusion of species that Haeckel has proposed. But it is not
skeletal characters only that are subject to change during growth.
Among the Collodaria, in which the spicules are a subordinate feature
and in some families entirely absent, the early stages of growth
differ so greatly from the later ones as to render their identification
a difficult matter and one particularly liable to misinterpretation.
Thus the genus Adissa, which Haeckel brought forward as the
most primitive of all Radiolaria, has been shown by Brandt (25) to
THE RADIOLARIA
in
be an early stage in species of the two families Thalassophysidae
and Physematiidae. Even the presence of developmental stages is not
decisive proof that the fertile protoplast or coenobium in question
is a final stage in the life-history, since in certain forms 1 an early
and variable reproductive stage is intercalated between the earliest
phase and that of full growth. Fission introduces further com-
plexities. The Acantharian genus Litholoplms was founded on
stages of growth or fission products belonging to other genera ; and
the division of the Collozoidae by fission leads to minute forms
that might easily be mistaken for young stages, although they are
reproductive individuals. We are thus led to the conclusion that
Fio. 8.
Racial dimorphism in Aulacantha scolymantha, x 26. (After Hacker.) A, deep-sea form ; B,
pelagic form from Naples, 100 fathoms. C.c, central capsule ; Exo, ectoplasm ; Ph, phaeodium ;
R, radial spicules ; Tf, tangential .spicules.
a knowledge of the life-history is essential to the construction of a
permanent classification, and that when this is obtained the species
will be groups segregated about their several types.
The dimorphism of Radiolaria is of two kinds : somatic and
gametic. Somatic dimorphism is at present known only in few
instances. It consists in the development of a small race of a
widely ranging species in warmer surface water, and of a large race
(usually three times the size of the former) in cold and deep water.
Associated with these differences of size there is structural diversity.
The spicules of the small race are fewer and simpler, the ectoplasm
they support is delicate and limp, often sagging between the
1 E.g. Collosphaera (Fig. 15, A).
112
THE RADIOLARIA
FIG. 9.
Radial spicules of A, abyssal form of Auloscena
vertitillatus ; B, pelagic form. (After Hacker.)
siliceous appendages. The skeleton of the large race ends in more
elaborate constructions, and stretches more tightly the tougher,
thicker ectoplasm that covers the animal. Such racial dimorphism
is known in Aulacantha scoly-
mantha (Fig. 8), Circoporus sex-
fuscinus, in Auloscena verticilla-
tus, and probably will be found
more commonly when looked
for. Both races are capable
of reproduction, and it is im-
probable that they merge into
one another, but it is not
known whether the mode of
reproduction is the same in
both.
Gametic dimorphism is
more general and perhaps uni-
versal, but is unaccompanied
by any known diversity of
somatic structure. It is there-
fore comparable with the di-
morphism of such Foraminifera
as Discorbina and Truncatulina,
and is signalised by the formation of isospores and of heterospores
in distinct and differently constituted individuals. These processes
involve the contents of the central capsule and are followed by the
death of the ectoplasm. An individual Radiolarian is therefore only
a phase in the life-cycle of its race, but the changes which lead up to
the formation of isospores are so distinct from those that precede the
development of heterospores, and involve such deep-seated nuclear
transformations, that it is difficult to believe that similar individuals
of any one generation can give rise to both forms of spore. On
this ground Brandt has been led to formulate the view that
isosporous and heterosporous individuals of any one species belong
to alternate generations. Direct evidence of this alternation has not
been obtained, and therefore the case of the Radiolaria is on a very
different footing from the observed alternation in Foraminifera.
Distribution : A, Vertical. — The recently published reports of the
German Plankton expeditions, though not yet complete, enable us
to picture the vertical distribution of the Radiolaria more accur-
ately than was formerly possible. The older records were derived
from surface townettings and from Ehrenberg's researches on
Radiolarian deposits at varying depths. They represented the
group as occurring at all depths, even on the sea-bottom, and as
increasing in variety with depth. The more recent exploring ex-
peditions give a very different result. From them it appears that
THE RADIOLARIA 113
in Atlantic and Antarctic waters — (1) the majority of Radiolaria
occur not deeper than 400 metres ; that the Collodaria are em-
phatically surface forms characteristic of the top stratum (0-50 m.) ;
(2) that in the next stratum below this (50-400) the great develop-
ment of Radiolarian, as also of diatomaceous, life occurs. Here the
majority of Acantharia, many Spumellaria, and many Phaeodaria,
e.g. Challengeridae, occur; (3) that in the still deeper water, 400-
1000 metres, a still richer Phaeodarian fauna and a few Acantharia
are met with, and that beyond this a few remarkable forms range
down to 5000 metres. The vertical distribution of the Nassellaria
is not yet adequately known, but it probably follows much the
same lines as that of the Phaeodaria.
B, Horizontal. — The distribution of the class is extremely wide,
as is readily understood from their dispersal by the great oceanic
currents. Some forms are panplanktonic, e.g. Aulacantha ; some
are bipolar: many are emphatically warm -water forms; others as
characteristically follow cold currents. Such considerations enable
us to understand the varying depths at which the same form may
occur as its chosen current occupies now a deeper, now a more
superficial position in the ocean. The greatest variety of species
is met with in equatorial waters, and this fulness extends in
diminishing variety north and south for some forty degrees. Then
there follows, at least in the northerly direction, as in the case of
many other pelagic orders, a barren zone, and finally Arctic waters
show a Radiolarian fauna that is rich in individuals though poor in
variety, and is apparently greatly inferior to that of Antarctic
(Hacker). This mode of distribution explains the comparative
poverty of the British Radiolarian fauna. Though the lack of
research makes reserve necessary, it seems certain that these waters
of the west and north-east coasts of Britain contain only a casual
Thalassicolla and a few Acanthometrida, Sphaerellaria, and Phaeo-
daria, outliers and stragglers of the rich Gulf Stream fauna.
The great northern host passes by the Faroes and off the Hebrides,
as the lists, pp. 144-151, show, and in those waters the researches
of Murray, Fowler, and Wolfenden have revealed a number of
interesting forms.
The deposits formed by the accumulation of Radiolarian
skeletons constitute a well-known element in the composition of
littoral and deep-sea Globigerina ooze and of red clay. They make
up certain of the clays, marls, and pumices found in the Miocene
deposits of Barbadoes, the Nicobar Islands, and on both sides of the
Mediterranean, as at Oran and Tripoli. Siliceous organic rocks
of Palaeozoic and of Mesozoic age have been recently discovered in
many parts of the world ; and microscopical investigations of these
rocks have revealed an unsuspected wealth of Radiolaria in them.
From the Cambrian age onwards, however, the families and even
114 THE RADIOLARIA
genera appear identical with those now living. Pre- Cambrian
Kadiolaria are still doubtful (Hinde [44]). The Sphaerellaria (Poly-
cystina) and Nassellaria are the chief contributors, since the
strontium skeletons of the Acantharia are readily soluble, and
therefore are unknown in recent deposits or in a fossil state, and
the hollow siliceous spicules of the Phaeodaria also appear in-
capable of resisting decomposition. Many skeletons formerly identi-
fied as Radiolarian (such as Dictyota and Mesoscena) are now referred
to the Flagellata or to other orders, but the Nassellaria Cyrtoidea
form the majority, the Sphaerellaria, Discoidea, and Sphaeroidea
the minority, of Jurassic Radiolaria in quartzites and coprolites.
In later deposits of Miocene ages this predominance is maintained,
but the species found are identical with or closely akin to living
forms.
Central Capsule. — The cytoplasm of Radiolaria is distinguished
from that of other Protozoa by the great development, specialisa-
tion, and delimitation of its ectoplasm. The boundary between
this peripheral layer and the central nucleated plasma is almost
always a distinct one ; and the few cases amongst the Acantharia
and Sphaerozoa in which no limiting membrane can be traced,
serve to show that this separation is the outcome of more primitive,
undifferentiated conditions, which the Radiolaria display in early
life, to which they revert during fission, and occasionally retain
throughout life.
The central capsule is the sign of this plasmic differentiation,
and the mark of a Radiolarian. It consists of a single, or in
Phaeodaria of a double, porous membrane of either chitinoid or
mucinoid nature. Usually the capsule is of such tenuity as to be
visible only after the use of reagents, or, as in Thalassicolla, it may
be comparatively thick and areolated by the growth of ridges on
its inner surface (Hertwig).
The shape of the capsule is in general correlated with that of
the configuration of the animal. In homaxonic Spumellaria and
Acantharia it is spherical ; in lenticular and discoid forms it is
ellipsoidal. In the bilateral Nassellaria it is elongate, and in the
Phaeodaria spheroidal; but in the recently discovered spherical
Thalassothamnidae it is lobate or branched (Fig. 10). The
consistency of the central capsule, however, is not that usually
associated with chitinoid structures. It is capable of extension,
and in the concentric Sphaeroidea and Discoidea it is lobate and
may enclose the inner shells one after another. In the helmet-
shaped Nassellaria it throws out lobes through the basal plate of
the shells. During the processes of fission and sporulation the
central capsule in all Radiolaria becomes more or less completely
dissolved to allow of the separation or escape of the endoplasmic
contents. These phenomena show that the capsule is no per-
THE RADIOLARIA
manent excretion, but is composed of a substance capable of
adaptation, by growth or dissolution, to changes in the endoplasm.
The walls of this structure are perforated by fine pseudopodia
that connect the endoplasm with the exterior in the manner
severally characteristic of the Peripylaria, Monopylaria, and
Tripylaria (pp. 102-9).
The evenly distributed or segregated pores of the first group
admit not only fine plasmic connections, but in Acantharia they
also transmit axopodia and radial spicules.
The single pore-plate of the Monopylaria, which, according to
•£x
Fio. 10.
Cytodadus spinosux. x 10. (After Schroder [38].) One of the Peripylaria, to show the
branched central capsule (C.c), the radiate single spicule (Sp), and the voluminous ectoplasm
supported by the spicular rays. It has been recently found off the coast of Japan.
Hertwig, consists of perforated, thickened rods of capsular mem-
brane, is not thoroughly understood. In most Nassellaria the
pores are, of course, confined to one plate-like extremity of the
.capsule, but they may be evenly distributed over the basal plate,
confined to a peripheral zone, or to three circles, which in Tridictyopus
project peripherally. Associated with this pore-plate is a peculiar,
.cone-like, fibrillated structure which projects inwards towards the
nucleus (Fig. 5, B, p). According to Hertwig this cone is an
invagination of the capsular membrane, and the fibrillae are con-
tinuations of those that pass through the pore-plate, on their way
to join the endoplasm at the apex of the cone. Biitschli, however,
Ii6 THE RAD1OLARIA
is inclined to consider the cone as due to the coalescence of axopodia
somewhat like those of the Acantharia (9, p. 439).
The central capsule of the Phaeodaria possesses well-marked
characteristics in its double nature and the presence and structure
of its main opening or astropyle and of its two lateral parapyles.
The former consists of a teat-like operculum apparently striated on
the inner side owing to the septate character of the subjacent
eridoplasm. The latter are made up of an inner bulb and an outer
cone which opens on a prominence. The endoplasm under the
bulb is also radially grouped, and in general it may be said, as
evidence of the interchange of plasma through the capsular pores,
that the endoplasm in their neighbourhood has a striated character.
The morphological character of the central capsule is a moot
point. Most authors, following Hertwig, hold it to be comparable
to the shell-membrane of a Thecamoeba, which, however, Dreyer
considers is covered by ectoplasm on both sides. It is possible, on
the other hand, that the capsule is a basement membrane peculiar
to the Radiolaria, and is a consequence of the differentiation of
their cytoplasm in relation to pelagic life. Until its development
is studied the question cannot be satisfactorily answered.
Cytoplasm. — The cytoplasm of Radiolaria, though one and con-
tinuous, is separable anatomically and physiologically into intra-
capsular and extracapsular portions.
Flotation and dispersal, nutrition and stimulation are offices
that devolve chiefly upon the ectoplasm ; storage and reproduction
upon the endoplasm. During the early and nutritive stage of life
the ectoplasm is predominantly active, during the reproductive
phase the endoplasm is solely operative. Continuity of structure
and community of function are expressed by an interchange of
protoplasmic and metaplastic granules through and beyond the
capsular wall.
The ectoplasm consists of four chief layers from within out-
wards : — an assimilative zone of dense protoplasm around the
capsule, a thick alveolar layer capable of secreting gelatinous and
fluid spheres, an enveloping membrane guarding the animal from
contact with its environment, and beyond this a fringe of radiating,
contractile pseudopodia. This great development is primarily
related to flotation. From Brandt's researches on the hydrostatic
function of Radiolaria it is clear that the calymmal gelatinous
spheres play the chief part of this office. These spheres he holds
are viscous secretions of the ectoplasm and absorb water from
without inwards. The specific gravity of the expressed fluid
is, however, such as to point to water saturated with carbonic acid,,
and as we pass from the inner to the outer zones of this alveolar
layer, the spheres are found to become more and more vacuolar,
until at the surface they are so tense as to collapse at a touch..
THE RADIOLARIA 117
Brandt therefore considers that the outer pseudopodia upon con-
tact with certain stimuli (wave-motion and heat) contract and
transmit the stimulus to the subjacent alveolar protoplasm. This
in turn contracts and the surface vacuoles collapse. When this
process has been continued for a certain time the specific gravity of
the animal is raised and a slow descent follows. Equilibrium
is again established, the vacuoles are re-formed, and the animal rises
again to the surface.
The calymmal spheres do not, however, monopolise the hydro-
static function. The flotation of Radiolaria is determined by
extension of its surface as well as by the lowering of its specific
gravity, and in this sustentative adaptation the outer pellicle
and the skeleton play the chief role. The skeleton of the
Acantharia is composed of a radiating series of tent-poles upon
which the ectoplasm can be raised and tightened by the elastic
filaments that pull up the baggy ectoplasm, which upon inflation
by vacuolar water expands, and so raises the animal to a higher
zone of water ; or again contracts, followed by deflation and sinking
of the whole mechanism.
Again, in Phaeodaria we have a still more elaborate skeleton,
the appendicular parts of which are related to the formation and
support of the ectoplastic membrane. In an impressive variety of
sustentative adaptations the ectoplasm of Eadiolaria deposits silicic
acid or strontium sulphate ; and the attempt now being made
to trace a correlation between the variation of this support,
the extent and thickness of the outer membrane, and the density
and viscosity of various tracts of water inhabited by widely
varying forms, has already met with some success (Hacker [35]).
Racial forms occur. Aulacantha scolymantha, for example, only
attains a diameter of 2 '3 mm. in warm surface waters; its ecto-
plastic membrane is soft and its spicules small and simple ; whereas
in deep, cold water (400-1000 metres) it reaches 7 mm. and
consists of a much tougher envelope supported by more numerous
spicules. Circoporus sexfuscinus and other Phaeodaria are also
dimorphic and exhibit a similar differential relation to the surface
and abyssal Avaters in which they occur.
The ectoplasm rarely contains assimilates or other inclusions.
Oil -globules, however, occur in the large Collodaria ; pigment
(blue, black, brown, or red) in the Thalassicollidae, Sphaeroidea,
Discoidea, and some Acantharia ; and concretions (probably
proteid) in some Thalassicollidae. Yellow cells are generally
present in the ectoplasm, and the only large division in which they
are unknown is that of the Phaeodaria. In the Acantharia,
however, they occur almost constantly in the endoplasm. A
further account of these cells is given below.
The myonemes are peculiar modifications of the basal ends of
n8
THE RADIOLAR1A
certain pseudopodia. They occur exclusively in the Acantharia
Acanthometrida, and form circular groups of short, rod-like bodies
clustered round each of the radial spicules (Fig. 11). Upon
careful examination they are found to connect the ectoplasm with
the pseudopodial covering of the spicule and to possess a high
degree of contractility. Their form varies accordingly. When
expanded the myonemes appear as homogeneous threads '006 to
•013 mm. long. When contracted they not only become shorter
(•012-'02) and thicker, but exhibit in many cases a very distinct
cross-striping. They are, in fact, muscular structures comparable
Sh.
M
Fio. 11.
Portion of a living specimen of Acanthometron pellucidum, one of the Acantharia, x900
(after Schewiakoff), to show endoplasm and ectoplasm. The latter consists of vacuolated
cytoplasm (E) slung up to the rod (S) by striated myonemes (.V), which are inserted into
the sheath (Sh) around the rod. In the endoplasm two nuclei (N) and zooxanthellae (Z) are
with the contractile fibrillae of Gregarines and Infusoria (Schewia-
koff [33]), and they serve to raise or lower the hydrostatic, ecto-
plasmic apparatus of these Radiolaria, and so to facilitate their
ascent or descent.
Another cytoplasmic modification of the Acantharia may here
be mentioned, namely, the axopodia. They consist of contractile
pseudopodia that radiate from near the centre of the endoplasm
to the periphery of the animal, and possess an axial fibre around
which an unceasing cyclosis of granules takes place. These
axopodia differ from the ordinary pseudopodia of the Acantharia
not only in their deeper origin but also in their more limited
THE RADIOLARIA 119
numbers and cyclical arrangement, and they resemble the peculiar
pseudopodia of such Heliozoa as Acanthocystis in all points except
in not arising from a centrosome. The peculiar cytoplasmic
threads that compose the so-called flagellum of the Discoidea are
also in all probability of a similar nature. This flagellum consists
of immobile pseudopodia fused into a tapering mass which projects
freely at one point of the ectoplasm, and its component pseudo-
podia, unlike those of the surrounding calymma, can be traced
almost to the centre of the endoplasm. They appear to spring
from the nucleus.
A peculiar accumulation occurs in the extracapsulum of the
Tripylaria, to which the name phaeodium is given. It consists of a
greenish or brownish mass concentrated about the main aperture of
the central capsule, but extends around the capsule for a third of
its extent. So constant and characteristic is this coloured mass
that the term Phaeodaria is frequently used as an alternative to
Tripylaria.
The constituents of the phaeodium in Aulacantha are various —
partly extrinsic, partly intrinsic. To the former class belong
diatoms and the debris of other vegetal organisms, small Radiolaria,
and Crustacea. Most of these undoubtedly represent food material ;
the diatoms, however, may be symbiotic. The characteristic
elements of the phaeodium are, however, the phaeodellae, which
consist of spherical or ellipsoidal corpuscles which vary from less
than 1 ju, to 20 /A in diameter. These corpuscles occur singly or in
masses. They appear homogeneous, granular, or striated, and vary
in colour from a hyaline transparency through yellow-brown, light
and dark green, to black. They may be free from inclusions or'
contain both blackish particles of varying size and refractive
granular spheres and rods. Towards reagents they show great
refractoriness, and do not give a uric acid reaction (Borgert).
About the nature of these phaeodellae, opinion has long been
divided. Haeckel maintained that they were symbiotic algae,
other zoologists that they were food particles. The recent
researches of Borgert on Aulacantha have suggested another
explanation. Borgert has pointed out the resemblance of certain
granules formed in the endoplasm in the neighbourhood of the
astropyle to these phaeodellae, and he regards these corpuscles as
excretory products of the endoplasm that pass out through the
capsule and accumulate in the surrounding ectoplasm. Recent
work on the brilliantly coloured algoid structures in bathybial
Challengeridae and Concharidae have shown that probably both
assimilation and excretion are carried on in the phaeodium (36).
Endoplasm. — The endoplasm is the site of storage and of
reproductive changes. It consists of a granular streaming
cytoplasm often highly vacuolated, and stratified radially and
THE RADIOLARIA
concentrically. Imbedded in it are fatty and proteid reserves,
pigment, crystalline structures, and one or more nuclei. Oil-
globules are generally present in the Spumellaria and Nassellaria,
fatty granules in the Phaeodaria. The fat may be colourless or
coloured red, yellow, brown, or blue. The pigment is often
closely associated with the oil-globules, and occurs in Thalassophysa
on the peripheral surface of the globules. The crystalline
Ph.
f,Arm
«£fti?3& <?l&fe X'^A
t\*S>r.. .''•:; ''**£-jyLi& s
,FU>r.
Portion of a section through Planktonetla atlantica, Borg., one of the Phaeodaria, to show
the phaeodium (Ph) tilling up the ectoplasm (Exo), x 80. (After Fowler.) Of. Fig. 29 for whole
animal. The black horizontal line is the "diaphragm" or ectocapsular membrane, that is
perforated by a single bundle of fibres (Fibr), if not also by the smaller similar structures (C).
In the upper ectoplasmic half of the figure the complex phaeodium is seen together with
branches (Sp) of the arms. In the lower half the delicate central capsule (C.c.) surrounds
thejendoplasm (End) and nucleus (Nu), and is itself enclosed in a shell (Sh) that forms a float.
structures are of two kinds : (a) small whetstone -shaped bodies
probably of albuminous nature ; and (b) large rhombic structures
indestructible at a red heat. The latter, regarded by Brandt as
excretory, are in all probability crystals of strontium sulphate
(Biitschli). With this exception the contents of the endoplasm
may be regarded as reserve material destined partly for the
metabolism of the animal itself, but more especially for the
provisioning of the spores, into which the endoplasm breaks up.
Nucleus. — The nucleus of the Eadiolaria is still very im-
THE RADIOLARIA 121
perfectly investigated, and the following statement can only be
regarded as a provisional account of its coarser features. The
two chief phases of life are signalised by distinctive characters in
the nucleoplasm. In the vegetative phase it consists of a single
large vesicular structure, or of a few derived from this by mitotic
division, or of many equivalent, amitotically produced, small nuclei.
In only a few cases are chromidia or other nuclear derivatives as
yet known to occur in this phase (Collosphaera, SiphonospJiaera, and
Aulacantha), and there is no separation of somatic and germinal
nucleoplasm. The Radiolaria are, in fact, homokaryota. Neverthe-
less, at the advent of the sporulating phase, the nucleus displays
new characters. Either it becomes differentiated and divides into
spore nuclei ; or it fragments partly into chromidia and plasma, which
recombine to form the spore nuclei, and partly into a residue which
perishes with the parental exuviae. In this process we can detect
a certain analogy with the extrusion of nucleoplasm during the
formation of the spores in the Heliozoa. But since the fate of
the Radiolarian spores is unknown, a just comparison of the two
cases is at present impossible.
The nucleus lies wholly in the endoplasm, and no chromidia or
other nuclear products have yet been recognised in the extra-
capsulum ; but the axopodia which radiate from the neighbourhood
of the nucleus in certain Nassellaria, the similar fibrillae that run
from the nucleus outwards to form the flagellum of the Discoidea,
are indications of the paths along which the nucleus probably exerts
its influence upon the ectoplasm, and vice versa. Further evidence
of this perinuclear sphere of influence is found in the apparently
porous character of the nuclear membrane (Physematium, Thalasso-
lampe, and certain Sphaeroidea) and the radial arrangement of its
peripheral plasma.
The characters of the nucleus vaiy according as to whether it
is a single or multiple structure. The Collodaria, Sphaeroidea,
Nassellaria, and Phaeodaria are generally mononuclear : the Sphaero-
zoa and Acantharia, polynuclear forms. In the first group the
nucleus is vesicular and differentiated into membrane, sap, chromatin,
and achromatin. In the second the nuclei are without a distinct
membrane, and, in the vegetative stage, homogeneous ; their origin
from the spore or zygote nucleus has been traced in no single
instance.
One or two special forms of nucleus may be referred to.
Among the Phaeodaria the majority possess a nucleus such as that
shown in Fig. 15, A, together, in some cases (Aulacantha scolymantha),
with chromatin particles scattered through the endoplasm. The
Tuscaroridae, however, are peculiar in having (Figs. 13 and 30)
an elongate nucleus, with a loop of chromatin enclosed by the
nuclear sap.
122
THE RADIOLARIA
Among the recently discovered and reinvestigated Spumel-
larian families, Thalassothamnidae and Orosphaeridae, a totally
new type of nucleus has been found (Schroder and Hacker). It
consists of a discoid structure
('1 mm. diam.) enveloped by
a crenate membrane, and is-
composed of a thin cortical
substance and a central mass-
of very distinct nucleoplasm,
the cortical and medullary
CA.
substances being separated
apparently by a membrane
(Fig. 14). The central
nucleoplasm contains segre-
The central capsule and nucleus of Tuscarora , -, £ i i i , • j
nationalis. (After Borgert.) As, the astropyle; gated, ICCbly Chromatised
Pa, the two parapylae ; Nu, the nucleus with its p-rnnnlPo imbedded in an
chromatin band (Ch). x 45. &'a
achromatic matrix ; the cor-
tical layer, on the other hand, is densely chromatised. The
most striking feature of this nucleus is perhaps the presence of
lenticular bodies at intervals along the junction of its two com-
ponent layers, or in one genus (Orosphaera) just outside it. These
contain large compact lumps of chromatin imbedded in a less-
densely staining medium. In addition to this central nucleus,
scattered, chromatin-like granules (Fig. 1 4, s) occur in the endoplasm,
and in Orosphaera these peripheral granules are unmistakable
nuclei of a simple character.
The shape and size of the nucleus often undergo considerable
change during growth. It remains vesicular, large, and spherical,.
FIG. 14.
Portion of a section through the
branched central capsule of Thalasso-
thamnus. (After Hacker.) The centre
of the capsule with its nucleus (N), endo-
plasm, and inclusions are shown. The
stratified concretions (s) stain with
haematoxylin, arid are probably chro-
midial structures. In Orosphaera (a
genus which, according to Hacker, is
closely allied to Thalassothamnus) these
peripheral nucleoplasmic structures are
capable of division. The nucleus (N)
shows well the division into crenate
membrane, peripheral chromatic layer,
and the central, mainly achromatic sub-
stance in which groups of staining
gran tiles occur. Large lenticular bodies
(/) of unknown significance occur also.
and more or less chromatised in the Thalassicollidae and'
Physematiidae ; but in the Thalassophysidae it becomes papillose,
elongate, and serpentiform, its plasma not only differentiates into1
inner and outer substances, but the spherical or thread -like:
THE RADIOLARIA 123
chromatin accumulates at its periphery (Fig. 21, A, B). In the
Sphaeroidea the nucleus becomes tubercular and follows the growth
of the central capsule, as this encloses successive shells. In the
simpler forms of Nassellaria the vesicular nucleus remains elliptical,
but in the Cyrtoidea, in which it lies near the apex of the shell, it
sends lobes (Fig. 4, 3) into the adjoining lappets.
The multinucleate Radiolaria offer other distinctive characters.
In the Sphaerozoa each individual of the colony possesses a gradu-
ally increasing number of structureless, singly refracting nuclei,
which multiply by direct fission, and have rather the appearance of
nuclear fragments than of true nuclei. In the case of Collosphaera
and Siphonosphaera, scattered chromidia (not associated as far as is
known with reproduction) occur as well. In Acantharia the multiple
nuclei have apparently a membrane and nucleoli, the multinucleate
condition is constant, and the distinction drawn by Haeckel between
such forms and oligo- or mononucleate Acantharia is a mistaken one
due to the presence of a parasitic Amoebophrya (Acinetaria), which
was mistaken for a nucleus (Part I. p. 423, Fig. 90). More difficult
to account for is the careful description by Hertwig of a temporary
nuclear condition discovered by him in a species of Acanthometron
and of Amphilonche. In the comparatively few nuclei of young
specimens, Hertwig found that the membrane became invaginated on
its peripheral side, whilst the massive nucleolus showed differentia-
tion into two parts. The neck of the infolded membrane became
radiately arranged, and its deeper portion creased into circular
folds lying one over another. After a time these appearances
vanished and the nuclei resumed their simple spherical form. The
phenomenon may be one of internal budding.
The advent of sporulation is prefaced and accompanied by
changes in the nucleus. These changes, however, are but imper-
fectly known (p. 139). Vesicular nuclei shrink, their membrane gives
way, and the altered chromatin and enclosed nucleoplasm either
flows out into the endoplasm or gives rise to a nuclear figure and then
disperses (see above, pp. 99-100, for Thalassicolla). From the frag-
mented material spore-nuclei arise. By the former method isospore-,
by the latter heterospore-, nuclei develop. In the Sphaerozoa, how-
ever, the homogeneous scattered nuclei remain undifferentiated
during the formation of isospores, and only exhibit a change from a
singly to a doubly refractive property ; but previous to the develop-
ment of heterospores their nuclei become modified into chromatic
and achromatic portions, which are further differentiated in the
mega- and microspores.
In the Phaeodaria the ellipsoidal nucleus is usually a single
large structure, but two or three nuclei may be present. It con-
sists (Fig. 14) of a membrane containing a linin network. The
chromatin is massed at the centre, and from this point radiating
124 THE RADIOLARIA
strands, threads, and lumps run outwards towards the periphery.
In addition to these chromatised elements, threads and granules of
another substance, the so-called paranuclein of Borgert (18), are
present. Nucleoli are absent.
The phenomena of nuclear division in this group have been
carefully studied by Borgert (17, 18) and Karawiew (16) in
Aulacantha scolymantha, but only mitotic division has been fully
described. Direct division of the nucleus without elongation is
known, but only a preliminary account has as yet been published.
The behaviour of the nucleus during sporulation is unknown.
Nuclear mitosis in Aulacantha exhibits five phases. In the first
or spirem stage, the linin threads form a dense coil, along which
the chromatin becomes arranged in a moniliform fashion ; a few
remnants, together with the paranuclein, lie scattered through the
nucleoplasm. The coil is in all probability never a continuous
thread, and no distinct centrosomes appear at this or any subse-
quent phase. The next stage consists of two events. The threads
of chromatin become cut up into varying lengths, and split longi-
tudinally so as to form rows of chromatin globules on either
side of the linin threads. The second event is the condensation of
these globules into thick short lengths of double chromosomes.
The pairs so formed are unequal in size and different in form,
some being spherical, some elongated or rod-like, but the members
of a pair are alike. Amongst these the paranuclein granules lie in
isolated heaps. The next or third stage is characterised by a
second longitudinal splitting of the chromosomes in a plane at
right angles to the first. The fission products separate, elongate,
and become thinner and twisted, leading up to the fourth stage or
second spirem phase, which is so far different from the first in that
the chromatin elements are obviously discontinuous, and the nucleus
as a whole has now become flattened, discoidal, and bent, in conse-
quence of the loss of its membrane, so that it presents, in side
view, a somewhat triangular outline, the apex directed towards the
astropyle. The large mass of chromosomes is now organised on
either side of a median transverse plane passing at right angles to
the flattened nucleus. The position of this plane is occupied by a
mass of short chromatin elements and debris, between which para-
nuclein granules occur. The chromosomes are aggregated on each
side of this central mass, which prevents them from being continuous
from one side of the nucleus to the other, and are more densely
crowded near the centre. The whole flattened structure stretches
out until on the aboral side it touches the central capsule. The
fifth phase is signalised by the appearance of the equatorial plate.
The origin of this structure has not been described, but the
chromosomes now arrange themselves in close relation to it, and
become heaped up in parallel series, though still maintaining marked
THE RADIOLARIA
125
differences of length and thickness. The plate becomes twisted
sigmoidally and divides parallel to its surface, the two columns
I
*
Fio. 15.
Mitosis in Aulacantha scolymantha. (After Borgert [18].) A, central capsule and resting
nucleus showing distribution of chromatin. B, second spirem stage showing commencing
separation of the chromatin. C, portion of sigmoidally curbed nucleus showing the equatorial
plate, and the chromosomes definitely arranged about the middle line. D, separation of the
two rows of chromosomes and of the two daughter plates into which the equatorial plate has
divided. E, central capsule showing the withdrawal of the daughter plates and commencing
reconstitution of the nuclei. A, B, and E x 150, C and D x 900.
of chromosomes move apart and organise two daughter nuclei
(Fig. 15).
126
THE RADIOLARIA
These complex mitotic phenomena offer many peculiarities, some
of which are discussed by Borgert. The absence of a spindle and
of centrosomes, the double splitting, great number and variety of
the chromosomes, the peculiar twisting of the nucleus and equatorial
plate, and the two spirem stages render this form of karyokinesis
unique ; and in spite of the labour which has been bestowed upon
its analysis, several points, such as the origin and fate of the equa-
torial membrane and the formation of the daughter nuclei, are still
obscure.
Yellow Cells. — Zooxanthellae occur commonly in the ectoplasm of
Spumellaria and Nassellaria ; in the endoplasm of Acantharia ; and
chr.
FIG. 16.
land 2, two specimens of Collozoum inerme, showing zooxanthellae (Z) in the ectoplasm, xlOO.
3, 4, and 5 are magnified views of a single xanthella, showing its escape as a biflagellated
organism from the cyst which it forms during the palmella state ( x 330). K, the nucleus ;
chr, the two chroma tophores ; the inclusions are hollow, amyloid grains. (After Brandt.)
are absent from the Phaeodaria. Their occurrence is facultative
and not absolutely constant. They are very abundant in orders
with a well-developed calymma such as the Collodaria (both mono-
zoic and polyzoic), less so in the Sphaerellaria, and in Physematiidae
with no extracapsular vacuoles, and are absent in the Discoidea.
Similarly, zooxanthellae increase in number with the increase of size
of the animal or coenobium in which they occur. Young colonies of
Collozoum up to 50 or 100 members contain few or no zooxanthellae,
older ones become impregnated with them.
The zooxanthellae of the Spumellaria are similar in structure
and behaviour to those of Thalassicolla (pp. 97-8). They are usually
spherical organisms with a single apparently homogeneous nucleus,
capable of assimilating carbon and of forming sheaths of a singly
THE RADIOLARIA 127
refractive amyloid substance around a clear centre. In the Collodaria
they vary from '015 to '025 mm. in diameter ; in the Sphaerellaria
from '005 to '01 mm. In the Nassellaria the zooxanthellae are
very small in some Cyrtoidea (Eucecryphalus) ; very large in others
(Eucyrtidium, Dictyopodium). A cellulose wall is present and en-
closes cytoplasm which contains two chromatophores impregnated
by chlorophyll and diatomin. In addition to the scattered hollow
vesicular, singly refractive structures that react to iodine by a
violet or bluish-violet tint, other doubly refractory granules occur,
and these are unaffected by iodine. After the death of the ecto-
plasm in which these zooxanthellae live, they pass into a palmella
stage and issue as biflagellated organisms upon a free stage. The
structure and life-history of these zooxanthellae prove that they
are organisms living in association with Eadiolaria, but it is not
possible to assign them to their true systematic position. Most
authors, following Biitschli, have placed them in the Crypto-
monadinae, a small heterogeneous group of simple algae ; but, as
Schaudinn has pointed out in his work on the zooxanthellae of
Trichosphaerium (42), it is also possible that these organisms have
quite other affinities. Brandt (10a) and Klebs (46) have drawn
attention to the similarity between the flagellated stage of the
xanthellae and the Peridinian Exuviaella marina. Further investiga-
tion of the behaviour of these yellow cells is necessary before their
position can be accurately denned.
Yellow Cells of Acantkaria. — The xanthellae of the Acantharia
differ in many ways from those of other Radiolaria. They are
mainly intracapsular, and always naked cells. In some families
they assume a spherical form, in others an irregular amoeboid shape.
These cells pass by easy transitions to mere heaps of pigment
granules. When numerous they vary in size from '006 to '008
mm. When few they attain a much larger size, '015 to '03 mm.
The latter, which are found in Acanthoniidae, Lithopteridae, and
Amphilonchidae, are probably the largest zooxanthellae known. In
Acanthonia tetracopa and other members of the same family, besides
the usual intracapsular mass of zooxanthellae, a few occur now and
then in the extracapsulum. In Dorataspis and Actinomma large
amoeboid zooxanthellae occur regularly in this position. These
structures are almost constant in Acantharia, but they are absent
in young specimens and in the few species taken in deep water.
The observations of Brandt (lOrt) on the finer structure of the
Acantharian zooxanthellae suggest that they have acquired a much
closer association with these Radiolaria than have those of Spumellaria
with their host, and that the older view of their nature was nearer to
the true significance of the association than the modern one that
regards the zooxanthellae as merely immigrant algae. Haeckel and
Hertwig regarded them as pigment cells formed by the segregation
128
THE RADIOLARIA
of the scattered granules and vesicles about so many nucleated centres-
in the endoplasm, and therefore as integral parts of the Radiolarian,
acting the part of storing reserve material. Brandt has shown that
their structure, though not suggesting this view of their origin, serves
to explain the connection between the pigment granules, pigmented
granular heaps, and definite yellow cells. Starting from the last,
with its single nucleus, plates of diatomin, numerous amyloid vesicles
and refractive granules, Brandt finds other xanthellae with multiple
minute nuclei, and by fragmentation of these yellow cells he accounts
for the presence of the isolated yellow granules, each of which, he
affirms, is a living corpuscle and possesses a very small nucleus
(lOa, p. 237). This degeneration of the zooxanthellar nucleus into a
heap of chromatin granules, associated with the breaking up of the
B
Fid. 17.
A-C, yellow cells (zooxanthellae) of Acantharia. (After Brandt.) A, large amoeboid cell
from Acanthonia tetracopa. B, C, spindle-shaped zooxanthellae (A. tetracopa). D, single xan-
thella of Thalassophysa sanguinolenta, to show its cell-wall (C.w), hollow, singly refractive
inclusions that stain bluish violet with iodine. G, doubly refractive granules unaffected by
iodine, x 1000. .
cell, is probably not to be explained through digestion of the yellow
cells by the Acantharian, but as a consequence of the intimate
association between the two structures. Unlike the zooxanthellae of
the Spumellaria, which live, divide, and sporulate after the death
and dissemination of their host, those of the Acantharia lose their
power of independent existence, and when the endoplasm in which
they occur becomes transformed into isospores or heterospores they
too pass into these spores in the form of granules and starch
grains. Thus the flagellated heterospores of Xipliacantha alata
(Fig. 26, A) contain a mass of yellow granules, besides an amyloid
body (staining blue with iodine), which is constantly present in the
iso- and heterospores of this species. It is therefore possible that
the yellow cells of Acantharia pass from mother to offspring, and it is
certain that amyloid deposits are so transmitted. The zooxanthellae
of Acantharia, therefore, once they have entered the Radiolarian,
THE RADIOLARIA 129
never leave it. They become assimilating granules, apparently
incapable of independent life, and are transmitted from parent to
offspring. In the former conclusion we have a remarkable parallel
to the history of the green cells (zoochlorellae) in Convoluta roscoffensis
(Keeble and Gamble [41]).
The nature of these interesting zooxanthellae is not satisfactorily
settled, but the scanty evidence points to affinities quite distinct
from those of the other Radiolaria. In the absence of a knowledge
of the life-history, Brandt's view is as likely as any other, but it is
by no means certain that all the Acantharian zooxanthellae are
of similar parentage. This view is that the zooxanthellae of
Acanthoniidae and Dorataspidae are isolated spindles of Labyrinthula
vitellina or of some allied species, and Brandt (10a, p. 239) points
out the agreement between the two structures in their shape, size,
colouring, and nuclei.
The association between Eadiolaria and the zooxanthellae is
usually regarded as a symbiosis, i.e. one of mutual advantage. It
is, however, clear from the foregoing description that no single
formula will cover the important facts — (1) that we have degrees of
intimacy that have grown up between the two organisms; and (2)
that the last term in the series of association is one to which
symbiosis in any but the widest sense of that term is inapplicable.
The origin of the association is probably to be traced to the
hunger for nitrogen on the part of the zooxanthellae ; to the
minimal quantity of inorganic nitrogenous food-stuffs in the warmer
seas (Johnstone [45]) ; and to the convergent adaptation of
Radiolaria and zooxanthellae to life at or near the surface of the
ocean. This pelagic and insolated station is attained by the
Radiolaria through the evolution of calymmal structures in which
nitrogen is in all probability abundantly present. These swarms
of inert mucilaginous Radiolarian capsules and colonies are therefore
in every way suitable media for the nutrition of the zooxanthellae.
Attracted in all probability chemotactically by the nitrogenous
stores in the mucilage, the zooxanthellae enter the ectoplasm and
then divide and assimilate. Protected by their cellulose envelope,
they can at first resist the digestive enzymes of their host;
ultimately, however, their nucleus becomes degenerate, and with
this change the protective wall, whose formation it governs, becomes
weakened. In this way some of the daughter-cells of the primary
zooxanthellae become food for their host (Famintzin). The
Radiolarian, which in its early stages fed on Peridinians, Infusoria,
and small Crustacea, ceases to ingest solid food and relies upon the
reserves it has accumulated or upon the secondary xanthellae for
its supplies. Meanwhile, its nitrogenous metabolism, and possibly
its intramolecular respiration, is maintained by the xanthellae,
which are removing the waste nitrogenous substances. In confirma-
9
130 THE RADIOLARIA
tion of this statement reference may be made to the Phaeodaria.
This group of Radiolaria possesses no zooxanthellae, and might
therefore be expected to show some accumulation of excretory
granules. This appears to be the case, for the complex phaeodium
is made up of refractory, insoluble vesicles which are generally
held to be excretory substances. The association of diatoms with
Radiolaria has probably a similar significance.
Finally, when the endoplasm sporulates the dying ectoplasm
serves as a medium in which the zooxanthellae rapidly divide and
issue as naked biflagellated spores upon a new, free existence. In
the case of the Acantharia, which are also mainly epiplanktonic
or surface organisms, the zooxanthellae are naked cells, almost
exclusively confined to the central portion of the Radiolarian.
Whether they develop from antecedent zooxanthellae that occur
in the spores of Acantharia or infect it from sea-water, or whether
both modes of origin obtain, is at present unknown. The apparent
absence of xanthellae from young Acantharia makes the first sugges-
tion unlikely. Within the central capsule they divide, multiply,
and assimilate. Certain of them fragment into particles, the
process being initiated by nuclear fragmentation, so that the
zooxanthellae are no longer cells but mere chromatised, pigmented
corpuscles, associated with free granules of starch or amyloid
substances. There is no evidence to show whether in this or in
the earlier coherent stage the xanthellae are digested by the
Acantharian. They become in the last event mere assimilative
corpuscles, and when the endoplasm sporulates the whole of the
zooxanthellae, with their associated starch, pass into the bodies of
the flagellated spores, and are probably used up as food by the
developing zygote. Throughout this series we see that, in opposi-
tion to the idea of mutual benefit, the animal is the predominant
partner. The association is one beginning with myxophytism and
leading to a case of parasitism, in which the zooxanthellae are the
host and the Radiolarian the parasite.
Skeleton. — The skeleton of the Radiolaria has developed in each
of the great sub-classes into a complexity of form and variety of
detail that are found in no other group of animals. So characteristic
are the skeletal products that it is usually possible from them alone
to recognise broadly the systematic position of the organism that
produced them. So complex and diverse a tracery seems utterly
beyond the needs of simple Protozoa living under apparently similar
conditions of pelagic life ; and though attempts have been made to
explain this manifold skeletal development in terms of cytoplasmic
structure, its variety still evades a biological treatment. Recent
investigation has, however, done something to reduce this variety
to a few plans, and to attach a biological meaning to some of its
elaborations. These results justify the hope that, as we come to
THE RADIOLARIA 131
regard the skeleton as a response to the varying media, stresses,
and strains that fall upon the cytoplasm from within and from
without, that then its utilitarian character Avill be more completely
recognised, and its variety found to be explicable in terms of com-
position, mode of deposition, and the need of response to widely
varying combinations of stimuli that occur in the apparently mono-
tonous sea. Two very different substances compose the greater
part, and probably the whole, of these skeletal structures. In the
Spumellaria and Nassellaria pure silica is present ; in the Phaeodaria
the silex is mixed with organic substance ; but in the Acantharia
a substance is present which, from the time when it was first
described by Johannes Miiller to the present, has given rise to
differences of interpretation. Miiller, relying on the indestructible
nature of the Acantharian skeleton when heated, regarded it as
siliceous. Haeckel found that it was apparently destroyed by heat,
and regarded it in the main as an organic horny substance which
he called acanthin. Schewiakoff (33) tested its properties and
attempted a quantitative analysis, the result of which went to show
that the so-called acanthin was a complex silicate. Quite recently
Biitschli (39) has rein vesti gated the skeleton of Antarctic and of
fiome Mediterranean Acantharia, and has proved that in these
cases it is composed of strontium sulphate.
The diverse forms of Radiolarian skeletons are largely founded
upon developments of scattered aciculate and tetrahedral spicules.
Dreyer has indeed attempted to trace the evolution of the skeleton
(1) in the Acantharia to an axopodial type derived from the
hardening of the axis that runs down the peculiar radiating
pseudopodia of this sub-class ; and (2) in other Radiolaria to the
modifications of a tetrad spicule, which in turn he traces to the
deposition of silica at the intersecting planes of adjacent cyto-
plasmic vacuoles or alveoles ; but the absence of a knowledge of
the development of the skeleton rendered this attempt suggestive
rather than convincing, and there are many forms of skeleton
which it is difficult to assign to any conceivable modification of the
tetrahedral type. In the present state of our knowledge it must
be admitted that the vacuolated cytoplasm has the power of
•depositing its silica in the form of perforate or imperforate shells,
plates, and processes, so that in addition to the spicules there is
often a great development of siliceous matter, the form of which
cannot be referred to the alveolar structure of protoplasm.
In form as in composition the skeleton of the Acantharia is
sharply marked off from that of other Radiolaria. With few
exceptions, it consists of twenty rods united in various ways : (1) by
opposition and also by adcentral processes ; (2) by fusion of all or
of opposite pairs, at the centre of the endoplasm. These radii are
.disposed so as to emerge from the spherical cytoplasm along five
132
THE RAD10LARIA
circles, which may be compared to the equatorial, the two circum-
polar, and the two tropical circles of the globe (Muller's law). In
a few cases two radii mark the vertical axis, and the other eighteen
are disposed in three circles — an equatorial one, and the other two
respectively 45° above and below it (Brandt's law) ; whilst in the
apparently primitive Astrolophidae the spines vary in number and
; — AX.
Fio. 18.
Acanthonia tetracopa in its two extreme phases of expansion and contraction, one half of the-
animal being drawn in each case. The relation of the myonemes to the ectoplasm, and their
insertion into sheaths around the radial spines, is also seen (cf. Fig. 11). The full number (20)
of spines is not indicated. (After Schewiakoff.) x 170.
possess no regular arrangement beyond their radial disposition.
This loose order is repeated in the early development of the Acan-
thoniidae. The young of this family possess ten loose rods arranged
crosswise, which subsequently become divided at the centre of
the capsule into the typical twenty radii. In the Acanthochias-
midae the distal portion of each radius gives off tangential processes-
which unite with those of adjoining spines and so form a perforated
THE RADIOLARIA 133
shell. By repetition of the process farther along the radii a second
and succeeding concentric shell may arise, In the most modified
case (Sphaerocapsidae) the lattice alone is present, but the place of
the radii is shown by twenty large pores distributed according to
Muller's law.
In the Spumellaria the skeleton is either absent, spicular, or
shelly. Both spicules and perforated shells are often present
simultaneously, and have evidently developed independently in
two of the main subdivisions — Sphaerozoa and Sphaerellaria.
But whilst in the former the shell is single, in the latter it often
becomes multiple, interconnected by radial bars, and flowers out
into a wealth of appendicular growths that characterise this vast
group, which numbers two-fifths of the known Kadiolaria. The
Sphaeroidea retain the homaxonial form ; the Discoidea have only
the first or first and second chambers spherical, and farther outwards
become flattened and often cruciform, the arms of the cross being
frequently divided into a large number of chambers, into all of which
the endoplasm and its associated pigmented oil-globules may pass.
Other modifications are mentioned in the conspectus (pp. 144-145).
In the Nassellaria, the Kadiolarian skeleton develops into its richest
expression of geometric form. Its simplest types consist of a single
or multiple ring and of a tripod or tetrad (see Fig. 5), and from
these a helmet-shaped perforated shell has arisen, apparently by
lateral extensions of the simpler plan. Such a cephalis may be
simple or divided both sagittally and transversely by one or more
constrictions, and in exceptional cases a spherical shell may be
developed. The most interesting feature of this group is that the
whole of its variety can be traced fairly confidently to the modifi-
cations of a single element which Biitsclili (8) believes to be a
ring and Dreyer (15) a tetrad spicule.
The skeleton of the Phaeodaria has followed another line of
evolution. It consists essentially of minute aciculate spicules
imbedded in a gelatinous matrix. Between these a jelly-like
substance is secreted ; the inner layer of this matrix becomes silici-
fied to form a tube, the cavity of which is often subdivided by one
or more septa ; or the intermediate jelly may also become silicified
as a porous plate or shell of porcellanous texture. Commencing
with the Phaeocystina, in which the skeleton is absent or composed
merely of isolated radial and tangential spicules, the formation of a
lattice-shell has come about in several ways. The simplest mode is
that seen in the Aulosphaeridae, in which the tangential spicules
unite to form an open peripheral network. To this a second shell
may be added by the formation of a reticulum immediately outside
the central capsule (Cannosphaeridae). If the outer shell is absent,
a condition found in the Castanellidae is obtained. In these
Phaeodaria the single shell is composed of two conjoined membranes
134 THE RAD1OLARIA
imbedded in a porcellanous impregnation throughout which minute
aciculate spicules occur. It is provided with an oral opening on the
end of a projecting and often spiny peristome. Again, this inner shell
may assume a bi valvular form (Fig. 32), and then carries a number
of complex appendages. Some of these are branching hollow
species, terminating in anchor-like expansions ; others constitute the
"galea" and "rhizocanna" (see Fig. 32, p. 151).
Biological Significance of the Skeleton. — The results of recent
investigation point to the conclusion that the chief skeletal function
is a hydrostatic one and is effected by stretching or folding the
superficial ectoplasm. The older conception of the skeleton as
projecting freely beyond the cytoplasm has been shown to be a
mistaken one in many instances, and it is probable that the skeleton
is during life covered by the outermost delicate plasmic layer
in all Radiolaria. Between the characters of this layer and the
development of the supporting rods a definite relation holds for
certain forms. A few widely varying Radiolaria are dimorphic, a
small pelagic variety and a larger abyssal form being readily and
apparently rightly distinguishable (Aulacantha scolymantha, Auloscena
and Sagosphaera-species). In these cases the surface-form possesses
a delicate ectoplasmic layer, and the supporting rods are simpler
and shorter, whereas in the bathybial variety the outermost
cytoplasm is dense, more voluminous, and usually more stiffly sup-
ported by verticillate skeletal projections. The graceful and
elaborate skeletal appendages of other Phaeodaria are probably to
be explained not as a means of catching food, but as a support for
the ectoplasm ; and the whole plan and construction of the tubular
skeleton in these forms is no doubt related intimately to the
pressures that fall upon this limiting layer.
In connection with this sustentative function of the Phaeodarian
skeleton, the mode of formation of its tubular systems offers some
features of special interest. The most general mode is that indi-
cated at the close of the last section (p. 133), and in this method
minute needle-like spicules form the centre around which tubular
developments of silica take place. But in addition to this intrinsic
centre, many Phaeodaria have adopted extrinsic objects, and around
these as catalysators, the tubular silica is deposited. Like other
Radiolaria, but to a greater extent, the Phaeodaria ingest quantities
of foreign bodies, with which their phaeodium is distended. Amongst
these ingesta, diatoms and Radiolarian skeletons are abundant.
From Phaeodaria, in which such gatherings are casual, we can trace
a series leading to forms in which diatom-selection becomes a regular
habit, associated directly with the formation of a radial skeleton.
Thus Aulographis pandora and Auloceros arborescens from the Atlantic
and Indian Oceans contain in their phaeodia frustules of lihizosolenia,
and spicules of many species of Aulacanthids picked up apparently in
THE RADIOLARIA
135
a casual manner, and probably serving to increase the extent of
exposed surface. Cannosphaera from Antarctic seas .possesses a
hollow skeleton the tubes of which are almost filled with masses of
the diatom Corethron ; and finally, in Aulokleptes (Fig 19) and
Aulodendron the diatoms are planted radially in the ectoplasm,
surrounded by a mucilage, and
finally incorpoi'ated into the walls
of a hollow radial tube, the lamellae
of which are laid down from within
outwards, and the top of which is
moulded into the form severally
characteristic of the species (Immer-
mann, Hacker).
The biological significance of
the varieties of Nassellarian spicule
and of the scattered Spumellarian
spicules and lattice - shells is at
present quite obscure, but the
skeleton of the Acantharia offers
perhaps the clearest case of func-
tional significance to be found in
the whole group (Dreyer, Brandt,
Popowsky). The twenty radial
spokes of the Acanthometrea serve
as so many tent-poles for the in-
sertion of the myonemes (Figs. 11
.and 18) that hoist the calymmal
cones. This action, combined with absorption of water into the
vacuoles, causes a swelling of the cytoplasm and brings the
animal towards the surface ; whereas relaxation of the myonemes
and contraction of the calymma depresses it beyond the reach of
wave-action. The skeleton of this subdivision is, however, related
to hydrostatic ends in another way. The definite arrangement of
the twenty spines according to what is known as Miiller's law
(p. 132) has recently been correlated with flotation and dispersal.
Brandt has shown that the distribution of the radii in five alternate
and superposed circles, each of four spicules, is such as to expose
them freely and without overlapping to the viscosity and resistance
of the water. The absence of vertical or axial spines is also intel-
ligible, since they would increase the weight of the body without
giving additional buoyancy. Moreover, the shape as well as the
arrangement of the spines assist the Acantharia in their flotation
and dispersal. Like all other Radiolaria, these are dependent on
currents and drift for their dissemination. In order to utilise this
horizontal force, the radial spokes are frequently provided with four
flanges or blades, which serve the double purpose of encountering
Fio. 10.
Spicule from Aulokleptes floscvlus formed
around a dividing diatom Rhizosoknia.
(After Immermann.) x 55.
136 THE RADIOLARIA
sustentative and propulsive forces. When these blades are wanting
and the spines are merely flattened, they are set in each of the
three circles, so as to turn the flat edge somewhat differently to the
water, the equatorial ones lying flat on the water, the tropical ones
turned half over, and the polar spines set on edge. By this means
the amount of resistance to the water in every direction is increased.
The exceptionally wide distribution of the Acanthometrida is some
confirmation of these deductions.
Fission — Reproduction. — The phenomena of multiplication and of
reproduction are still imperfectly known. Binary or multiple
fission occurs in some Spumellaria, Acanthometrida, and Phaeodaria.
Gemmation is a rarer mode. It produces the extracapsular bodies
of the Spliaerozoidae, and is found in one species of the Acantharia
and of the Phaeodaria respectively. The development of zoospores
is a general phenomenon, but has been followed in detail only in a
few cases. Plastogamy is unknown.
The mode of increase by fission is probably restricted to those
Radiolaria which have no spicules or a lax and osculate skeleton.
Binary fission occurs in the Thalassicollidae, some Acanthometridae,
and in two families of Phaeodaria. Division both of the Sphaero-
zoid colony and of its component individuals takes place at intervals.
Multiple fission occurs in the Thalassophysidae. The process is
usually initiated by changes in the endoplasm and nucleus, and a
long interval may follow before any corresponding alterations occur
in the ectoplasm (Phaeodaria).
In the Acanthometrida (Acanthoniidae) binary, quatenary,
and multiple fission are said to occur (Popowsky). The former
process is illustrated in Fig. 20. The skeletal rods separate at
their central ends into two bundles, the nuclei segregate into two
groups, the central capsule divides, and ultimately fission takes
place. The fission - products are, however, asymmetrical, and
Fig. 20 shows how the new radii are developed and how the rods
are swung into position, probably by contraction of the myonemes
inserted into them, until the whole arrangement is brought into
conformity with Muller's law.
Fission in the Phaeodaria is carried out in several ways.
Aulacantha scolymantha is the best-known example of the direct
process. In this Radiolarian the large single nucleus divides either
by mitosis or amitotically ; the endoplasm segregates round the
daughter nuclei ; the central capsule, after disappearing for a time,
re-forms about the two masses. Lastly, the phaeodial complex, the
calymma and spicular skeleton are subdivided each into two groups,
and the whole organism divides into two. In the Phaeodaria,
which possess a shell, one or more modifications of the process are
found. The helmet-shaped Challengeridae, for example, undergo
fission within the shell. One half of the organism now escapes
THE RADIOLARIA
137
through the oral aperture and develops into a new individual
{Borgert [2 la], p. 100).
The most remarkable case of multiple fission occurs in the
Thalassophysidae, and constitutes the only known means of increase
FIG. 20.
Illustrating fission in the Acanthometrida. (After Popowsky.) A, Acanthometrnn bifidum
about to divide. The spicules are arranged in two bundles. The central capsule has dis-
.appeared. The ectoplasm is a mere hyaline border round the granular endoplasm, x!50.
1$, lission of Amphilonche atlantica. My, the myonemes, xloO. C, regeneration of the same ;
formation of a directive large spicule, x 150. D, spicules reassuming their characteristic
arrangement, x 150.
in this family. Fig. 21 illustrates the process, which has been
investigated by Brandt (25). The central capsule and nucleus
become irregular-branching, vermicular, or radiating structures.
The oil-globules and their associated pigment granules become dis-
seminated through the endoplasm. Then the nucleoplasm breaks
tip into a vast number of minute homogeneous corpuscles, followed
138
THE RADIOLARIA
by rapid division of the capsule and endoplasm. The ectoplasm
fragments and the products are disseminated through the water.
Each minute product consists of several nuclei lying in a pigmented,
oily fragment of endoplasm and supported by a portion of the
original ectoplasm. The further history of these bodies is unfortu-
nately not known.
Cc
FIG. 21.
Multiple fission in Thalassophysidae. (After Brandt.) A, central capsule and nucleus of
Th. spiculosa, x 40. B, section of the nucleus to show the two zones of nucleoplasm and the
vermicular nucleoli in the outer layer, x 66. C, Th. pelagiea about to divide ; the nucleus has
undergone fragmentation. D, multiple fission of the central capsule of Th. pelagica. E,
enlarged view of a portion of the same, x 200. F, stained portion of capsule of the same ta
show nuclei before fragmentation of the capsule. G, division of central capsule of Th. sanguino-
lenta, x 7. C.e, central capsule ; N, nucleus of vegetative individual ; NI, nucleus of frag-
menting individual ; On, In, outer and inner zones of endoplasm.
The separation of a portion of the Radiolarian organism as a-
bud is a rare phenomenon, of which the " extracapsular bodies " of
the Sphaerozoidae offer the best example. These structures occur
in small colonies of Cullozoum inerme, C. radiosum, C. fulmim, and of
Sphaerozoum neapolitanum. They consist of a lobate, highly refrac-
tive, cytoplasmic mass, containing a group of modified nuclei
ranged about a grape-shaped mass of fat, and are loosely attached
to the colonial jelly (Fig. 22). These extracapsular bodies are
budded off from the endoplasm of certain members of the colony in
which they occur, and are at first uninuclear. According to Brandt's-
THE RADIOLA1UA
139
account (10) these bodies have a twofold significance. Either
they become additional members of the parental colony and develop
central capsules, or they become megaspores and the small parental
endoplasm develops microspores. In his later work Brandt lays
additional stress on the latter fate. He has not only seen the bean-
shaped active megaspores formed by the extracapsular bodies, but
(26, p. 264) also the mass of microspores formed by the small
capsules which had budded off these bodies : a proterogynous
arrangement. It should be added that Brandt affirms very strongly
the juvenile nature of these small budding colonies ; whilst Famintzin,
FIG. 22.
Collozoum sp. Portion of a colony showing extracapsular bodies (E.C).
x 100. (After Brandt.)
working in the same locality, asserts that their small size is due to
fission of full-grown coenobia (13).
Spore - Formation. — Flagellated spores occur in the four main
divisions of the Radiolaria, but their exact nature is only known in
some Collodaria and some Acantharia, and it is in the former order
that their formation has been traced. The process is described for
Thalassicotta on pp. 99-102.
Isospores. — The development of isospores in the Sphaerozoa
takes place in colonies distinct from those that produce heterospores.
After a vegetative life of several months these colonies exhibit
characteristic changes (Fig. 25). The nuclei become ranged in a
single or double row just beneath the capsular membrane. Without
becoming obviously differentiated, these lumps of chromatin divide
directly and acquire a doubly refractive character. Hundreds of
140
THE RADIOLARIA
minute crystals arise in the endoplasm, a few larger ones also in certain
Collosphaeridae. The single oil-globule of each capsule becomes
very rapidly subdivided into as many minute vesicles as there are
nuclei, and in association with this process a blue pigment develops
•S,
FIG. 23.
Collosphaera huxleyi. Optical sections of different growth-stages to illustrate (A, B) dimor-
phism (Si, S'>) in early and later stages, and (C, D) the formation of isospores. A, young actively
dividing colony (the young reproductive phase of Brandt, comparable with the. formation of
extracapsular bodies in Sphaerozoidae). Many individuals are naked central capsules with
one or more nuclei ; others have a shell (.S']) and are larger and already provided with
zooxanthellae (z). B, later vegetative phase. The naked capsules have now secreted a large
shell (.S2), and a marked dimorphism has resulted. C, part of a full-grown colony about to
sporulate. The formation of isospores is indicated by the grouping of the nuclei. D, later
stage in isospore-formation showing the crystals aggregated about the oil-globule. x 75.
(After Brandt.)
in Myxosphaera coerulea and Collosphaera huxleyi. Numerous vacuoles
arise in the centre of the capsule, each with a central granule, until
a number equivalent to that of the nuclei has been formed. Mean-
time these nuclei, which have become very numerous, are evenly
THE RADIOLAR1A
141
disseminated through the endoplasm forming the centres about each
of which a crystal, an oil -vesicle, a vacuole, and granule are
Fio. 24.
Portion of a colony of Sphaerozoum neapolitanum about to form isospores. The spicules and
"yellow cells" are omitted. The central capsule has disappeared, and only a thin peripheral
ectoplasmic layer is present. Minute crystals are scattered through the endoplasm, and two-
oil-globules (o) are shown. X 300. (After Brandt.)
clustered. The whole endoplasm is now transformed into a mass
of biflagellated spores. The central capsule suddenly disappears,,
and the ectoplasm, which in the interval has undergone contraction
ci
B
Fio. 25.
A, formation of isospores in Collozoum inerme. Two stages are shown on opposite sides of
a central capsule. On the left side the nuclei and crystals are aggregated peripherally, but the
central oil-globule is intact. On the right the nuclei are smaller and more numerous and the
oil-globule is breaking down. B, formation of heterospores in the same shown by quadrants,
a, early stage ; several grouped, modified nuclei and fat-granules ; between the groups are undif-
ferentiated nuclei and endoplasm ; 6, c, and d are later stages.
and degeneration, breaks to pieces. The colony descends and the-
isospores swarm out, leaving (in the Collosphaeridae) the large
crystals and the greater part of the pigment behind. Each is a-
142
THE RADIOLARIA
conical structure ('012 mm. long). From its pointed end spring
the two cilia, one of which is usually held in a somewhat horizontal
position, the other curving backwards and downwards. Near this
end lies the nucleus, which has acquired, according to Brandt
(10, p. 163), a certain differentiation. The broader end is filled
with the crystal and granules (Fig. 26, E).
Heterospwes, — The formation of megaspores and microspores
may proceed from the same (Sphaerozoidae) or separate colonies
FIG. 26.
Isospores and heterospores of Radiolaria. A, heterospores of Xiphacantha alata (Acantharia).
B, isospores of the same. C and D, microspore and megaspore of Collozoum inerme. E,
isospore of the same showing crystal and inclusions. F and G, megaspores of Sphaerozoum sp.
H, microspores of the same. (After Brandt.)
(Collosphaeridae). The process differs from the development of
isospores in the presence of segregated nuclei, the differentiation in
the nuclei of achromatic substance, and the dimorphism of the mega-
and micro-nuclei. In the Collosphaeridae the full-grown vegetative
.colony shows the first traces of heterospore- formation by the
segregation of its homogeneous nuclei into groups of 2, 4, or 8.
This arrangement is temporary, and very soon the nuclei are
found arranged in several layers, each nucleus being now clearly
composed of a highly refractive and achromatic ground-sub-
>stance, in which are imbedded thread-like masses of chromatin.
THE RADIOLAR1A 143
According to the colony under consideration so will these nuclei
belong either to the microspore or megaspore. In the former the
chromatin is disposed in stout granules and thick strands, in the
latter in much smaller quantity. In other respects the colony
behaves precisely as in the formation of isospores.
In the Sphaerozoidae the formation of heterospores takes place
both in small, apparently young, colonies that bear extracapsular
bodies and also from full-grown vegetative colonies. In both cases
many of the nuclei become segregated and differentiated, the endo-
plasm in which they lie acquires distinctive characters, and the
groups so formed are separated by undifferentiated plasma and
nuclei (Fig. 25, B). The oil-globule becomes subdivided into a grape-
like mass, which ultimately splits up into minute granules, and
these are collected around the specialised nuclei. In the case of
colonies bearing extracapsular bodies the whole of this bud becomes
transformed into megaspores, the contents of the central capsule
becoming microspores. In older colonies the endoplasm is con-
verted into a vast number of portions, in each of which the differ-
entiated nuclei are aggregated. These nuclei are, however, not all
of one kind. Each collection is either meganucleate or micro-
nucleate, and accordingly stains feebly or strongly. The contents
of the capsule now becomes resolved into biflagellated megaspores
and microspores, the ectoplasm degenerates and collapses, the
central capsule deliquesces, and the spores become disseminated.
Little is as yet known as to the formation of isospores and
heterospores in other Radiolaria. In Acanthochiasma rubescens
(Acantharia) Brandt records the early development of two kinds of
bodies — one with crystalloid inclusions, the other with lobulated
masses of fat. The same observer has described the active spores
of XipJiacantha alata and Acanthometra sicula. Two kinds of spores
occur in these Acantharia (Fig. 26, A, B). Both are minute
('004 mm. long), and provided with three cilia, which spring from
the two poles of the spheroidal or pear-shaped body, but they differ
in that the spores of any one individual either contain a minute
crystal and few granules or many granules but no crystal. Both
are provided with a starch-grain (see pp. 128), and traces of the
yellow cells of the parent occur in the granular variety. It seems
highly probable, therefore, that crystal-bearing isospores and granular
heterospores occur in this sub-class as in the Spumellaria ; but
although the results of more recent expeditions have extended very
largely the number of Acantharia in which the early development
of spores has been shown to occur, the free spores have not been
again noticed; nor do we possess any exact observations on the
flagellated bodies that have occasionally been seen in Nassellaria
and Phaeodaria.
144 THE RADIOLARIA
CLASSIFICATION.1
CLASS RADIOLARIA.
SUB-CLASS I. PERIPYLARIA (Spumellaria).
Central capsule homaxonic, uniformly perforated by numerous similar
and extremely small pores. Skeleton siliceous. Extra-capsulum volum-
inous (except in Physematiidae).
ORDER 1. Collodaria.
Large monozoic forms not forming a true coenobium. Skeleton absent
or spicular.
FAMILY 1. PHYSEMATIIDAE. Large vacuoles confined to the endoplasm.
No stratified concretions in the latter. No pigment. Few " yellow cells."
Nucleus spherical, with smooth membrane and a few rounded nucleoli.
Selected forms : — Physematium miilleri, H. ; Thalassolampe margarodes, H.,
Mediterranean and Canary Islands ; Lampoxanthium murrayanum, Fowl.,
Faroe Channel. The genus Actissa of Haeckel is an early stage of growth
of some species of this family.
FAMILY 2. THALASSOPHYSIDAE. Large vacuoles extracapsular.
Structure similar to that of the Thalassicollidae, but nuclear membrane
usually tubercular or papillary. Reproduction by rapid and peculiar
fragmentation (Fig. 21). Spores unknown. Selected forms : — Thalas-
siosolen atlanticus,Wolf. (28); Thalassophysa pelagica, H. (Fig. 1), Faroe
Channel ; T. sanguinolenta, H. ; T. papillosa, H., Mediterranean and
Canary Islands (often deformed by ingested Coccolithophoridae). For
further account of this family see Brandt (25).
FAMILY 3. THALASSICOLLIDAE. Nuclear membrame smooth and
spherical. Stratified concretions present in the endoplasm. Multiplica-
tion by binary fission, by isospores, and by heterospores (see Fig. 2 ;
Brandt [25, 25a, and 26]). Selected forms : — Thalassicolla nucleate/,, Hux.,
Valencia Harbour, Faroe Channel, and cosmopolitan ; T. spumida, H.,
Canary Islands ; T. pellucida, H., cosmopolitan.
FAMILY 4. THALASSOTHAMNIDAE, Hacker (37). Skeleton in the
form of a large single radiate spiculum or of a double spiculum. Central
capsule sometimes spherical, characteristically lobed or branched.
Nucleus complex. Nuclear membrane crenate (Fig. 14). Endoplasm with
stratified inclusions. Selected forms : — Thalassothamnus ramosus, Hack.,
Antarctic ; Cytocladiis spinosus, Schroder (Fig. 10), Japan Seas (38).
FAMILY 5. OROSPHAERIDAE. Protoplasm organised as in the preceding
family. Skeleton a perforated shell with branched and thorny spines.
Orosphaera, H., deep water of mid-Atlantic. This family has been re-
moved by Hacker (37) from the Phaeodaria, with which group Haeckel
associated it ; but if the presence of a phaeodium, astropyle, and parapyles
is confirmed, its systematic position will have to be revised.
1 The number of genera and species in this class is so large that only a selection
can be referred to here. North Atlantic forms have been chiefly selected.
THE RADIOLARIA 145
ORDER 2. Sphaerozoa.
Colonial forms.
FAMILY 1. SPHAEROZOIDAE. Both mega- and microspores developed
in the same individual. A lattice-shell absent. Selected forms: —
Collozoum inerme, Norway (Figs. 3, s, and 25) ; C. pelagicum, Shetlands ;
Sphaerozoum ovodimare, Faroe Channel.
FAMILY 2. COLLOSPHAERIDAE. Mega- and microspores in separate
individuals. Skeleton, when present, takes the form of a lattice-shell
with or without associated spicules. Selected forms : — Oollosphaera huxleyi,
Mediterranean (Fig. 23) ; Choenicosphaera murrayana, Shetlands.
This order is treated fully by Brandt in his Monograph (10) and (22).
ORDER 3. Sphaerellaria.
SUB-ORDER 1. SPHAEROIDEA. Central capsule and shell (or shells)
spherical. Selected forms : — Hexalonche philosophica, H., Faroe Channel ;
Hexacontium enthacanthium, Jorg. ; H. pachydermum, Jorg., North Sea ;
Hexadoras borealis, Clev., North Sea ; Echinomma, leptodermum, Jorg.,
Norway and Sweden ; Rhizoplegma boreale, Clev., Norway.
SUB-ORDER 2. PRUNOIDEA. Central capsule and shell elliptical or
cylindrical ; often with transverse constrictions. Selected form : — Pruno-
carpus datura, H., Faroe Channel.
SUB-ORDER 3. DISCOIDEA. Central capsule and shell discoid or
lenticular; often much flattened. Selected forms: — Trochodiscus
heliodes, Cler., North Sea ; T. echiniscus, H. ; Lethodiscus microporus, H. ;
Astrosestrum acanthastrum, H. ; Spongodiscus favus, Ehr., Faroe Channel.
SUB-ORDER 4. LARCOIDEA. With lentelliptical central capsule and
shell. Selected forms : — Lithelius minor, North Sea ; L. arborescens, H.,
Faroe Channel ; Phorticium pylonium, H., Norway and Sweden.
SUB-ORDER 5. SPHAEROPYLIDKA. With basal or basal and apical
pylome (large opening to the shell). See Dreyer (15).
SUB-CLASS II. ACANTHARIA.
Radiolaria in which the skeleton is composed neither of the so-called
horny acanthin nor of silica, but (in many cases) of strontium sulphate.
The central capsule is perforated uniformly or in networks and segregated
pores. The skeleton has the form of spicules radiating from a central
point within the capsule (Acanthometrida). Rarely a fenestrated
extracapsular skeleton is added (Acanthophractida).
ORDER 1. Acanthometrida.
SUB-ORDER 1. ACTINELIIDA. With 10-200 radial or diametral spines
not arranged according to Miiller's Law (p. 132).
FAMILY 1. ASTROLOPHIDAE. Spines radiating from a common centre.
Genus 1. Adinelius. All spines of equal length and similar shape. A.
purpureus, H., Mediterranean. Genus 2. Astrolophus. Spines of unequal
length.
10
146 THE RADIOLARIA
It is probable that further investigation of the Actineliida will clear
up the anomalies that at present attach to their isolated position. They
are regarded by Haeckel as the ancestral stock of the whole Itadiolaria.
The family Litholophidae which he associated with them is now regarded
as composed of growth-stages of the genus A canthonia.
FAMILY 2. ACANTHOCHIASMIDAE. "With ten or sixteen diametral
spines irregularly arranged. Genus Acanthochiasma. With ten spines,
A. fusiforme, found near Plymouth and in the North Sea. A. cruciata,
A. krohnii, generally distributed in the Atlantic.
SUB-ORDER 2. ACAXTHOXIIDA. With twenty spines arranged in four
zones of five spines to each (Muller's Law).
FAMILY 1. ACANTHOMETRIDAE. Spicules circular in transverse
section. Genera — Acanthometron ; proximal end of spines without flange ;
A. pellucidum, N. and E. Scotland. Phyllostaurus, with flange ; Ph.
quadrifolius, abundant in North Atlantic.
FAMILY 2. ZYGACANTHIDAE. Spines compressed and double-edged,
lanceolate in section. Genus — Zygacantha, without flange at base of
spines ; Z. septentrionalis, North Atlantic.
FAMILY 3. ACANTHONIIDAE. Spines cruciform in cross section.
Genus — Acanthonia ; A. rnulleri, N. Scotland and North Sea; A.
ligurina, W. coast of Greenland ; Acanthonidium ; A. echinoides, North
Sea, Faroes and Norway ; A. pallidum, N. and E. coasts of Scotland.
FAMILY 4. AMPHILONCHIDAE. Two opposite spines much larger than
the rest. Genus — Amphilonche. A. belonoides, generally distributed
in the Atlantic. For the exotic family Lithopteridae, see Haeckel's
Monograph (11).
ORDER 2. Acanthophractida.
SOB-ORDER 1. SPHAEROPHRACTA. With twenty radial spines of
equal size. Shell spherical.
FAMILY 1. SPHAEROCAPSIDAE. Shell composed of very numerous
small plates each with a single pore. Genera — 1. Sphaerocapsa. Sph.
cruciata, Faroes, North Atlantic. 2. Astrocapsa. A. tritonis and A.
coronata, Faroes and North Atlantic. 3. Porocapsa. P. murrayana. 4.
Cannocapsa. G. osculata, Faroe Channel and North Atlantic.
FAMILY 2. DORATASPIDAE. Shell composed of the meeting branches
of two to four apophyses given off by the twenty radial spines. Seventeen
genera are known, mostly from equatorial or southern waters.
FAMILY 3. PHRACTOPELTIDAE. Shell double ; the inner one
enclosed by the central capsule. No genera known from northern
waters.
SUB-ORDER 2. PRUNOPHRACTA. Two or six spines much larger than
the rest. Shell not spherical.
FAMILY 1. BELONASPIDAE. Shell ellipsoidal. Two enlarged spines.
The genus Platnaspis occurs in North Atlantic and Mediterranean.
FAMILY 2. HEXALASPIDAE. Shell lentelliptical. Six enlarged
spines. The genus Hexaconus is known from the North Atlantic.
FAMILY 3. DIPLOCONIDAE. Shell diploconical with two opposite
large funnels (the sheaths of the two enlarged spines). Pseudopodia con-
THE RADIOLARIA 147
fined to the two polar apertures. The genus Diploconus is known from
the Mediterranean.
SUB-CLASS III. MONOPYLARIA (Nassellaria).
Radiolaria with monaxonic central capsule that bears at one pole a
porous plate forming the base of an inwardly directed cone.
SOB-LEGION 1. Plectellaria.
Without a complete lattice-shell.
ORDER 1. PLECTOIDEA. Skeleton a basal tripod (Fig. 5). Selected
forms : — Plagiacantha arachnoides, Clap., W. coast of Norway, North Sea ;
Plagiocarpa procyrtella, EL, North Atlantic, Iceland ; Hexaplagia arctica,
H., Greenland ; Polyplagia novenaria, H., Faroe Channel, North Atlantic ;
Plectophora arachnoides, H., and PI. novena, H., North Atlantic and Faroe
Channel, North Sea.
ORDER 2. STEPHOIDEA. Skeleton a sagittal ring, and usually no
tripod. Selected forms : — Lithocircus annularis, Mull. ; Cortiniscus
iypicus, H. ; Eucoronis nephrospyris, H. ; all cosmopolitan.
SUB-LEGION 2. Cyrtellaria.
Skeleton a complete lattice-shell (cephalis).
ORDER 1. SPYROIDEA. Cephalis bilocular with cephalic construction.
Almost exclusively southern forms.
ORDER 2. BOTRYOIDEA. Cephalis multilocular. Selected forms : —
Sotryocampe inflata, Ehr., cosmopolitan ; Phormobotrys hexaihalomia, H.,
Mediterranean.
ORDER 3. CYRTOIDEA. Cephalis single, without constrictions or lobes.
Selected forms : — Tridictyopus elegans, Hert., Mediterranean ; Cornutella
£lathrata, Ehr., cosmopolitan ; Cyrtocalpis obliqvM, H., cosmopolitan ;
Lithomelissa thoracites, H., cosmopolitan ; L. setosa, H., Norway ; Eucecry-
phalus gegenbauri, H., cosmopolitan ; Carpocanium diadema, H., cosmo-
politan ; Dictyocephalus ocellatus, H., Faroe Channel ; Dictyophimus clevei,
Jorg., Norway ; Theoconus ariadnes, H., cosmopolitan ; Cladoscenium
tricolpium, Norway ; Clathrocyclas craspedota, Norway.
SUB-CLASS IV. TRIPYLARIA (Phaeodaria).
Radiolaria in which the central capsule is double and usually
possesses a chief aperture (astropyle) and two accessory apertures (para-
pyles). A dense resistant pigment (phaeodium), probably of excretory
nature, accumulates in the extracapsulum. The skeleton is siliceous and
.often made up of hollow tubes.
ORDER 1. Phaeocystina.
The skeleton consists of isolated spicules.
FAMILY 1. AULACANTHIDAE. Skeleton of tangential needles and radial
;hollow rods. Selected forms : — Aulacantha scolymantha, H., Hebrides,
148
THE RADIOLAR1A
Faroe Channel, Shetlands ; Aulographis zetesios, Borg. ; A. furcellata,
Wolf., Faroe Channel ; Au. tetrancistra, H., Norway ; Aulodendron boreale,
Wolf., Faroe Channel.
ORDER 2. Phaeosphaeria.
Skeleton composed of an extracapsular shell or of two concentric
shells separated by the extracapsulum. Outer shell usually spherical.
FAMILY 1. SAGOSPHAERIDAE. Outer shell a lattice-work with
triangular or areolar meshes. Selected forms : — Sagena ternaria, H. ;
Sagosphaera trigonilla, H., cosmopolitan ; Sayenoarium sp., Jorg, Norway.
FAMILY 2. AULOSPHAERIDAE. An outer lattice-shell alone present,
the hollow bars of which contain septa. Selected forms : — Aulosphaera
flexuosa, H., Faroe Channel ; Auloscena verticillatus, H., Norway ; Aulotractus
fusulus, H., Faroe Channel, Hebrides.
FAMILY 3. CANNOSPHAERIDAE. Inner and outer lattice- shells present,
interconnected by radii. Cannosphaera antarctica, H., bipolar form.
FAMILY 4. POROSPATHIDAE. Inner shell alone present, composed of
two finely grained membranes ; elliptical
*EXO. or ovoid. Mouth at the end of a curved
process.
\--Pa.
ORDER 3. Phaeogromia.
-Cc.
-As.
A single simple shell present, variable
in shape, but always provided with a
projecting peristome.
FAMILY 1. CHALLENGERIDAE. Shell
monaxonic, composed of two layers which
exhibit an extremely fine diatomaceous
graining. Peristome toothed. Selected
forms : — Lithogromia silicea, H., Faroe
Channel ; Protocystis tritonis, H., Faroe
Channel, Shetlands, North Sea ; Pr,
tridens, H., Norway and Sweden ; Pr.
harstoni, Murray, Norway ; Pr. xiphodon,
H., Faroe Channel ; Challevgeron trioden,
balfouri, golfense, johannis, armatum (Fig.
27) ; Cadium melo, Clev. ; Pharyngella
gastrula, H. ; Entocannula hirsuta, H. ;
Faroe Channel.
FAMILY 2. MEDDSETTIDAE. Primary
shell alveolar. Peristome with articulated
surroundedby processes and its aborai feet ^ secondary shell may be developed
surface bears a crest (Exo). The central . . * J
capsule possesses two astropyles (As), in relation to the phaeodium.
two parapyles, and two nuclei. The A q 11 t (avertm-ncr 0-1 mm
brown phaeodellae (Ph) are shown. *• »lndil S ^averaging U 1 mm,
(From a living specimen, after Borgert.) in diaui.), with primary shell and few
radial spines. Phaeodium in primary
shell. Euphysetta nathorsti, Clev., North Sea, Scotland ; Mediisetta
tiara, H., Faroe Channel.
B. Small forms (0-8--3 mm.), with hooded primary shell provided
Fia. 27.
Challengeron armatum, Borg. x 225
The mouth (M) of the perforated shell is
THE RADIOLARIA
149
with six long radial spines. Phaeodium still in the primary shell.
Gazelletta, Fowler.
C. Large forms, with conical shell, completely filled by central
FIG. 28.
Atlanllcella craspedota,
Borgert. In this newly
discovered family of Phaeo-
daria the central capsule
(C.c) is a large inflated
4 - lobate structure. The
skeleton consists of a me-
dian hollow part (M.Sk) and
of four pendent septate
arms (Sp). The black area
is the phaeodium (Ph).
x 50. (After Borgert.)
P.h:
capsule, which is converted into a swim-bladder. A diaphragm, perfor-
ated (Hacker [37]) by several astropyles and parapyles, separates
endoplasm from ectoplasm (Fig. 12). Phaeodium outside primary
Ph.
FIG. 29.
Planktonetta atlantica, Borgert.
(After Fowler.) x 66. The entire
animal is shown as seen in a pre-
served specimen. One pair of arms
is omitted. The central capsule
(End) is invested by a skeletal
membrane and forms a float. The
arms are embedded in the phaeo-
dium (Ph) and attached to this
is the outer shell (F), comparable
with that of Medusetta and Atlanti-
cella. A section through this
animal is seen at Fig. 12, p. 120.
Erui
shell, with intra-phaeodial skeleton. A float present. Planktonetta
atlantica, Borg., Faroe Channel (29, 37).
D. Large forms, without primary shell. Central capsule a swim-
bladder. Diaphragm and phaeodial skeleton as in preceding sub-family.
Secondary shell projecting over peristome. No float. Nationaletta.
THE RADIOLAR1A
E. Mid-sized forms, without primary shell. Secondary shell with
four arms. Atlanticella. (Fig. 28.) Borgert (21).
FAMILY 3. CASTANELLIDAE. Primary shell two -layered and com-
posed of (1) extremely delicate tangential siliceous needles; (2) the
two conjoined limiting membranes of the two layers, united by (3) a
porcellanous impregnation. Selected form : — Castanidium apsteini,
bipolar (36).
FAMILY 4. CIRCOPORIDAE. Shell composed as in Family 3, but
spherical, polyhedral, or multipolar (36).
FAMILY 5. TOSCARORIDAE (Fig. 30). Shell rarely spherical, gener-
ally monaxonic. Nucleus elongated with sigmoid chromatin band.
(Borgert [2 la].)
FIG. 30.
Tuscaroridae. A, Tuscarusa globosa, Borgert, showing the peristomial hollow spines ;
the rest are broken off. x 39. B, Tuscarora nationalis, Borgert, showing the two central
capsules in the shell. Each capsule contains a bent nucleus, x 24. (After Borgert.)
ORDER 4. Phaeoconchia, H.
Central portion of the skeleton in the form of two valves, free or
hinged together.
FAMILY 1. CONCHARIDAE, H. With thick valves, which are devoid
of an apical cupola and of radial tubes. Equatorial and southern
forms.
FAMILY 2. COELODENDRIDAE. "With extremely thin valves, each of
which bears a cupola and tubular processes. Goelodendron ramosissimum,
Faroe Channel and cosmopolitan.
FAMILY 3. COELOGRAPHIDAE. Each cupola provided with a hollow
process (rhizocanna), which communicates with the cupola by a paired
or unpaired frenulum. Radial tubes strongly developed, sometimes
forming an outer bivalved mantle. The largest and most complex
THE RADIOLARIA
Fio. 31.
Coelothamnus davidoffii, Btitschli ; one of the Phaeodaria. Entire animal drawn from a dead
specimen, x 4. Sixteen radii spring from the bivalve shell (S) which encloses the central
capsule. The ectoplasm (E) is shown investing the skeleton which supports it on the anchor-
like extremities of its tufted appendages. (After Btitschli.)
Radiolaria (20-30 mm. in diara.). Selected forms: — Coeloplegma
murrayanum, H. (Fig. 32) ; G. tritonis, H., Faroe Channel.
As
Fio. 32.
Central capsule and adjacent structures of Codoplegma murrayanitm, H.; one of the Coelo-
graphidae. The bivalve shell (S) supports the hollow-branched galea (G), in which the phaeo-
dellae are seen emerging through the aperture (R) of the nasal tube (rhizocanna). The astropyle
(As) is drawn out into a tube.
LITERATURE.
1. Ehrenberg, Ch. G. Monatsberichte d. Berliner Akad. 1844-73.
2. - - (Fossil Species.) Abhandl. d. k. Akad. Berlin, 1872, pp. 131-397.
3. Huxley, T. H. (Thalassicolla.) Annals and Mag. Nat. Hist. vol. viii.,
1851, pp. 433-442.
152 LITERATURE OF THE RADIOLARIA
4. Miiller,. J. (Fundamental Treatise.) Abhaudl. d. Berliner Akad. 1858,
pp. 1-62.
5. Haeckel, E. Die Radiolarien. Berlin, 1862.
6. Cienkowski. (Yellow Cells.) Archiv f. mikros. Anat. vii., 1871, pp. 372-381.
7. Hertwig, R. (Structure of Radiolaria. ) Jenaische Denkschriften, vol. ii.,
1879, pp. 129-277.
8. Biitschli, 0. (Skeleton of Nassellaria.) Zeit. f. wiss. Zool. vol. xxxvi.,
1881, pp. 485-540.
9. (Monograph.) Bronn's Thierreich, Protozoa, vol. i., 1885, pp. 332-478.
10. Brandt, K. (Sphaerozoa.) Fauna v. Flora d. Golfes von Neapel, vol. xiii.,
1885.
10a. (Zooxanthellae.) Mittheil. Stat. Neapel, iv., 1883.
11. Haeckel, E. (Monograph.) Challenger Reports, vol. xviii., 1887.
12. Lankester, E. Ray. Radiolaria in Encyclopaedia Britannica, Art.
"Protozoa," pp. 20-23 of reprint.
13. Famintzin, A. (Life -History, Food, and Yellow Cells of Sphaerozoa.)
Memoires de 1'Acad. Sci. St. Petersbourg, 7th series, vol. xxxvi. No. 16,
1889, p. 21.
14. Verworn. (Thalassicolla.) Pfliiger's Archiv f. Physiologic, vol. li., 1891,
p. 118.
14a. (Hydrostatics.) Ibid. vol. liii., 1893, pp. 140-155.
15. Dreyer, F. (Evolution of Radiolarian Skeleton.) Jenaische Zeit. f.
Naturwiss. vol. xxvi., 1892, pp. 204-468.
16. Karawiew. (Fission in Aulacantha.) Mem. Soc. Natur. Kiew. vol. xv.,
1896.
17. Borgert, A. (Reproduction of Tripylaria.) Annals and Mag. Nat. Hist.
(6), xviii., 1896, pp. 422-426.
18. (Fission in Aulacantha.) Spengel's Zool. Jahrb. Anat. vol. xiv.,
1900, pp. 203-274.
19. (North Atlantic Tripylaria.) Nordisches Plankton, Lief, i., 1901,
pp. 1-52.
20. (Tripylaria of the German Plankton Expedition. ) Zool. Jahr. Syst.
vol. xix., 1904, pp. 733-760.
21. (Atlanticellida.) Ergeb. Plankton-Expedition, vol. iii., 1906.
21a. (Tuscaroridae. ) Ibid. vol. iii., 1906.
22. Vernon, H. M. (Respiration in Collozoum.) Journal of Physiology,
vol. xxi., 1897, p. 443.
23. Brandt, K. (Bionomics of Acantharia.) Ergebnisse d. deutschen Plankton-
Expedition, vol. i., 1892, p. 338.
24. (Hydrostatics.) Zool. Jahrbiicher Syst. vol. ix., 1895, pp. 27-74.
25. (Thalassophysidae.) Archiv f. Protistenkunde, vol. i., 1902.
25a. (Division of Thalassicolla.) Mitteil. d. Vereins Schlesw.-Holstein.
Aerzte, 12. Heft, 1890.
26. (Thalassicollidae.) Ibid. vol. vi., 1905, pp. 245-271.
27. (Classification of Sphaerozoa.) Zool. Jahrb. Suppl. vol. viii., 1905,
pp. 311-352.
28. Wolfendcn, R. N. (Radiolaria of Faroe Channel and Shetlands.) Journal
Marine Biol. Assoc. N.S. vol. vi., 1902, No. 3. Trans. Linn. Soc. vol. x.,
pt. 4, 1905.
29. Fowler, G. H. (Planktonetta.) Quart. Journ. Mic. Sci. (2), vol. xlvii.,
1903, pp. 133-143.
LITERATURE OF THE RADIOLAR1A 153
30. Fowler, G. H. (GazellcUa.) Quart. Journ. Mic. Sci. (2), vol. xlviii., 1904,
pp. 483-488.
31. - - (Radiolaria of Faroe Channel.) Proc. Zool. Soc. 1896-98, pp. 991, 523,
1016.
31a. Popowsky, A. (North Atlantic Acantharia.) Nordisches Plankton, Lief,
iii., 1905, pp. 43-69 ; Lief, v., 1906.
32. (Acantharia.) Ergeb. Plankton -Expedition, 1904; Appendix in
Archiv f. Protistenkimde, vol. v., 1905, pp. 339-357.
33. Schcwiakoff, W. (Skeleton, Myonemes, and Flotation of Acantharia.)
Me'moires de 1'Acad. des Sci. St. Petersbourg, vol. xii., 1902, No. 10.
34. Immermann, F. (Aulacanthidae.) Ergeb. Plankton-Expedition, vol. iii.,
1904.
35. Hacker, V. (Biological Significance of Tripylarian Skeleton.) Jenaische
Zeitschrift f. Naturwiss. vol. xxxix., 1905, pp. 581-648 ; Zeit. f. wiss.
Zool. vol. Ixxxiii., 1905, pp. 336-375 ; Archiv f. Protistenkunde, vol. ix.,
1907, pp. 139-169.
36. (Challengeridae, Tuscaroridae, Circoporidae of the Valdivia Expedi-
tion.) Archiv f. Protistenkunde, vol. viii., 1906 ; and Verhandl. deutsch.
zool. Gesellschaft, vol. xiv., 1906, pp. 122-156.
37. (Thalassothamnidae, Medusettidae. ) Zool. Anzeiger, vol. xxx. , 1906,
No. 26, pp. 878-895 (16 figs.).
38. Schroder, 0. (Cytocladus.) Zool. Anzeiger, vol. xxx., 1906, pp. 448 and
587.
39. ButscJili, G. (Strontium Sulphate in Skeleton of Acantharia, etc.) Zool.
Anzeiger, vol. xxx., 1906, No. 24, pp. 784-789.
40. Delap, M. and C. (Irish Thalassicollidae.) Scientific Investigations, Irish
Fisheries, 1905 (vii.) [1906].
41. Keeble, F., and Gamble, F. W. (Green Cells of Convoluta. ) Quart. Journ.
Micr. Sci. vol. 1L, 1907, pp. 167-219.
42. Schaudinn, F. (Trichosphaerium.) Abhandl. d. kgl. preuss. Akad. Wiss.
Berlin, Supplement, 1899.
43. Patter, E. (Respiration of Protozoa.) Zeit. f. allgemeine Physiologic,
vol. v., 1905, pp. 566*612. Ibid. vol. vii. pp. 46-53.
44. Hinde, J. G. (Fossil Radiolaria.) Quart. Journ. Geol. Soc. vol. Iv. pp.
38-64.
45. Johnstone, J. (Summary of Recent Work on Marine Nitrogenous Food-
Stuffs.) Science Progress (N.S.), vol. ii., 1907, pp. 191-210.
46. Klebs, G. (Yellow Cells and Peridinians.) Bot. Zeitung, vol. xlii., 1884,
p. 721.
THE PEOTOZOA (continued)
SECTION F. THE MASTIGOPHORA l
CLASS MASTIGOPHORA.
SUB-CLASS I. LISSOFLAGELLATA.
Order 1. Monadidea.
Tribe 1. Pantostomatina.
Sub-Tribe 1. Holomastigoda.
^ „ 2. Rhizomastigoda.
Tribe 2. Protomastigina.
Sub-Tribe 1. Monomastigoda.
„ 2. Paramastigoda.
„ 3. Heteromastigoda.
„ 4. Isomastigoda.
Tribe 3. Polymastigina.
Sub-Tribe 1. Trimastigina.
,, 2. Monostomatina.
„ 3. Distomatina.
„ 4. Lophomonadina.
Order 2. Euglenoidea.
Tribe 1. Euglenina.
„ 2. Astasiina.
„ 3. Peranemina.
Order 3. Chromomonadidea.
Tribe 1. Chloromonadina.
„ 2. Chrysomonadina.
,, 3. Cryptomonadina.
SUB-CLASS II. CHOANOFLAGELLATA.
Order 1. Craspedomonadina.
„ 2. Phalansteriina.
SUB-CLASS III. PHYTOFLAGELLATA.
Order 1. Chlamydomonadina.
„ 2. Volvocina.
SUB-CLASS IV. DINOFLAGELLATA.
Tribe 1. Gymnodiniaceae.
,, 2. Prorocentraceae.
„ 3. Peridiniaceae.
SUB-CLASS V. CYSTOFLAGELLATA.
SUB-CLASS VI. SILICOFLAGELLATA.
1 By Arthur Willey, F.R.S., and Prof. S. J. Hickson, F.R.S.
154
THE MASTIGOPHORA 155
THE unicellular organisms which are associated in the class Mastigo-
phora or Flagellata in the wide sense, comprise a very heterogeneous
assemblage of forms, having in common the possession of certain
characteristic traits of organisation (a single nucleus, one or more
contractile vacuoles, one or more flagella), and further united together
phyletically by the occurrence of transitional or annectant types.
Our knowledge of the group dates back to the time of Anton
Leeuwenhoek, at the beginning of the eighteenth century, while
the foundation of the modern system may be safely attributed to
the labours of Christian Gottfried Ehrenberg during the early part
of last century (1830-1838).
From the most general point of view the peculiar biological
interest of the Mastigophora rests upon the fact that, in this more
than in any other class of Protista, the formal distinctions which
are commonly drawn between the animal and vegetable kingdoms
vanish. It was formerly a question whether such and such an
order of Mastigophora should be reckoned among the unicellular
Algae or among the Protozoa, but this controversy is now practi-
cally over, and biological disquisitions upon the group are equally
at home and equally necessary in zoological and botanical treatises
and journals.
When an organism possesses a green colour, due to the presence
of chloroplasts stained with chlorophyll, has a cell-wall that gives
the chemical reactions of cellulose, and is devoid of a mouth for the
ingestion of solid food, it is usually regarded as a plant. When,
on the other hand, an organism bears no chlorophyll, has no cell-
wall, or has a cell-wall that does not give the cellulose reaction,
and possesses a mouth for the ingestion of solid food, it is usually
regarded as an animal.
If it were possible to divide the Mastigophora into two
divisions, one containing all those forms provided with a mouth
and devoid of chlorophyll and a cellulose cell-wall ; and the other
containing all those forms without a mouth, bearing chlorophyll and
surrounded by a cellulose cell-wall, then the former division could
be assigned to the animal kingdom and the latter to the vegetable
kingdom. Such a division would, however, be thoroughly un-
scientific and unnatural. It could only be made by deliberately
ignoring obvious genetic relationships. Moreover, such a division
would leave out of account a number of organisms — particularly
Monadidea — which fail to fulfil all the conditions for their admission
into either of the divisions.
It is not by the study of any one stage of the life-history of
these organisms that it is possible to arrive at any clear conception
of the best distinction that can be drawn between the animal and
vegetable kingdoms.
The study of the whole life -history of some of the lower
156 THE MASTIGOPHORA
animals and plants, however, suggests a line of distinction which is
perhaps more in accordance with a natural system of classification.
In the life -history of Ulothrix, one of the Ulotrichaceae, an
example of an organism that is universally regarded as a plant, we
find two forms of cells. There are the cells of the filamentous
thallus, protected by a cell-wall, containing chlorophyll, and, under
favourable conditions, growing and increasing in number by fission ;
and there are the cells provided with two or four flagella that
escape from their cellulose investments and eventually conjugate to
form a motionless zygospore.
If we compare this with the life-history of such a form as
Mastigella, one of the Mastigophora that is universally regarded as
an animal, we find that during the phase of life when growth and
repeated multiplication by fission occurs the organism is actively
moving about by means of its flagellum or its pseudopodia, and that
the gametes that it gives rise to are also active and flagellate.
Any period in the life-history of Mastigella when active movements
cease is not, as in the case of Ulothrix, a period of vegetative
growth.
If we regard, then, as marks of distinction between an animal
and a plant (1) that the stage of growth and reproduction of
somatic cells by fission is marked by a period of active mobility in
the former, and of stability in the latter ; and (2) that the flagellate
cells of the latter do not grow and divide by fission, but conjugate
and give rise immediately to a sedentary zygospore, whereas in the
former the flagellate cells may grow and divide by fission, we
represent a consideration which has had considerable weight in
determining the action of zoologists in including the Mastigophora
in the animal kingdom. But the boundary thus drawn, even if it
is the best that can be drawn, is itself subject to some exceptions.
In some of the Chlamydomonadina we find, for example, that
flagellate individuals similar in general characters to the gametes
form a gelatinous investment, withdraw their flagella, grow and
divide repeatedly by fission. It is difficult to distinguish this phase
of life (the " palmella-stage," as it is called) from a true plant under
the terms of our definition. The close relation of the Chlamy-
domonadina to the Chromomonadina, however, is so clear that to
separate them by placing one order in the vegetable kingdom and
the other in the animal kingdom on this ground alone would be
absurd.
The life-history of the Chlamydomonadina seems to support
very strongly the view that some of the families of the lower Algae
have sprung from a flagellate ancestry, but it does not justify the
assumption that the vegetable kingdom as a whole owes its origin
to the class Mastigophora.1
1 See Blackman and Tansley (2), and West (22, pp. 32 et seq.).
THE MASTIGOPHORA 157
It is principally in respect of their modes of nutrition that the
Mastigophora appear to betray the mixed animal and vegetable
properties, so that as a class they have come to be regarded as
mixotrophic micro-organisms. The four possible methods of ali-
mentation— holozoic, parasitic, saprophytic, and holophytic — are all
to be met with among the members of this protean series, either
separately or in combination. When a single species can vary its
metabolism in adaptation to its immediate environment, for example,
according as it is exposed to or deprived of the influence of light,
it is said to be mixotrophic in the strict sense of the term (Pfefl'er).
It is not always easy to assert positively in Avhat manner food is
conveyed into the protoplast (protoplasmic body of the cell), but it
is certain that holozoic nutrition is often associated in the same
species with saprophytic (Monadidea), saprophytic with parasitic,
saprophytic with holophytic (Euglenoidea), and, more rarely,
holozoic with holophytic (Chromulina). Sometimes three methods
are found in combination — holozoic, saprophytic, and holophytic
(Ochromonas). It may be stated as a general rule that all Lisso-
flagellata (i.e. true Flagellata in the restricted sense) are capable of
saprophytic nutrition, that is to say, of absorbing nutriment from
putrescent substances in an aqueous medium, but that this source
of food is usually accessory to some other essential means of
nourishment. Where saprophytism is the sole condition of exist-
ence, as in the case of the Astasiina, there is reason to regard it
as a secondary state derived, in the particular instance quoted,
from a condition of holophytism.
The parasitic forms may be described broadly as falling inta
three categories : ectoparasites (Costia, Stylochrysalis, Silicoflagellata) ;.
endoparasites (species of Hexamitus, Megastoma, Tetramitus, Tricho-
mastix, Trichomonas, Trichonymphidae) ; and haematozoa (Trypano-
soma, Herpetomonas).
The non-parasitic Mastigophora are either free -swimming or
sessile, solitary or colonial in habit.
Some species are capable of temporary fixation by means of a,
protoplasmic stalk either of pseudopodial (e.g. Oicomonas sp., Fig. 5
(31)) or of flagellar (e.g. Bodo sp.) origin. Some solitary free forms-
are closely related to solitary fixed forms (e.g. Euglena, and Ascoglena),
and many free-swimming colonial genera have sessile representatives-
(e.g. Dinobryon and Hyalobryori).
The form of association of individuals in the colonies varies
within limits, and there is a great amount of parallelism in this
respect between members of different orders. An entire colony or
coenobium may attain to a certain degree of individuation, which is
most marked in the Volvocina, but is not wanting in other groups,
as is evident from the co-ordinated movements which they execute
and from the fact that the whole coenobium may undergo binary
158 THE MASTIGOPHORA
fission (Uroglena). On the other hand, the units often retain a
facultative independence, and the coenobium may then undergo
dissociation (Synura).
The principal forms of association of individuals are the follow-
ing : — 1. Linear aggregates, e.g. Hirmidium, Chlorodesmus, Ceratium;
2. Rosettes, e.g. Bicosoeca socialis, Cydonexis annularis, Gonium pedorale ;
3. Plates, e.g. Proterospongia, Platydorina ; 4. Spherical aggregates, e.g.
Sphaeroeca, Uroglena, Volvox ; 5. Dendroid associations, e.g. Dinobryon,
Hyalobryon, Poteriodendron, Anthophysa, Ehipidodendron, Dendromonas,
Phalansterium.
Of the above colonial assemblages it is to be remarked that the
dendroid form is the most polymorphic in actual appearance. As
for transitional forms, it is not difficult to construct a series, while
analogies are stupefying in their abundance. Thus a biserial linear
aggregate like Chlorodesmus in comparison with a rosette like Cydo-
nexis is absolutely paralleled by species of the pelagic Ascidian, Salpa.
A transition from a rosette to a plate is afforded by Gonium, and
from a rosette to a spherical aggregate by the volvocine genus
Stephanosphaera, in which the units are arranged in a rosette
though surrounded by a common gelatinous envelope.
The Mastigophora as a class may be defined broadly as uni-
nucleated Protista which perform their movements by means of one,
two, or several flagella, usually arising at or near the anterior end,
i.e. the end which is directed forwards during locomotion. The typical
motion of the flagellum has been described as one of circumduction
(Delage), by which the cell is drawn along at the same time that
it rotates about its axis. The flagellum of a typical Flagellate
Infusorian is therefore a tractellum, as opposed to the tail of a
spermatozoan, which is a pulsellum.1 It acts, however, as a pulsellum
in exceptional cases among the Monadidea, and with the Choano-
flagellata when they quit their attachment in order to effect change
of position.
According to the number, position, and proportions of the
flagella we recognise monomastigote forms, with a single porrect
flagellum ; paramastigote, with one or two small accessory flagella at
the base of the main one ; isomastigote, with from two to four equal
flagella ; heteromasligote, with divergent flagella, one directed forwards
or transversely, the other directed backwards ; polymastigote, with
more than four flagella ; to which may be added holomastigote forms,
with numerous flagella distributed over the entire surface of the
cell. The disposition of the flagella has a distinct systematic
importance, but of much more limited application than was formerly
1 The terms " tractellum " and " pulsellum " were suggested by Prof. Lankester.
In some elongate metabolic species (Astasiina) the tractellum is directed straight
forwards, and only the apical portion of it executes rapid vibrations, drawing the body
.along without rotation.
THE MASTIGOPHORA 159
supposed, since the phenomenon of parallelism is as strikingly dis-
played in this respect as in the manner of formation of colonies.
The heteromastigote condition merits particular notice since it
characterises an entire sub -class (Dinoflagellata), where the one
flagellum is transverse, usually lying in an annular depression, while
the other is longitudinal and is also partially protected by a groove,
but extends backwards freely (Fig. 10). This is a special mani-
festation of the heteromastigote condition, but equally interesting
examples occur in many families of Lissoflagellata, where the
anterior flagellum is normally directed forwards (tractellum) and
the posterior flagellum which arises from the body of the cell close
to the former is trailed behind. The posterior flagellum in these
cases exerts a directive and modifying influence upon the move-
ments of the Infusorian, serving also as an anchor and sometimes as
a spring promoting a rapid jerking movement of leaps and bounds
like the tail of a Podurid.
The posterior flagellum of heteromastigote Mastigophora may
be aptly described as a gubernaculum (Fig. 7 (10)) and referred to by
that term.
The flagellum is usually so extremely attenuated that it is
very difficult to discover any structure in it, but as its base
may often be traced from the surface through the ectoplasm to the
endoplasm, it seems probable that it
consists of an axial filament derived
from the endoplasm and a delicate
cortical sheath derived from the ecto-
plasm. It is interesting to note that
in the Ehizomastigoda there is an
endoplastic axial filament in the pseudo-
podia (Fig. 1). It is impossible to
draw any morphological line of dis-
tinction between a flagellum and a
cilium, and in the Lophomonadina, for
example, the vibratile processes have Fia *•
been interpreted as flagella by those Anffl^ofS'SUlS
who regard this group as belonging g^£5&£ ffi£ 5£SS?K!
to the Mastigophora and as cilia by («*)<* the pseudopodia (ps);/, flagel-
.1 i j •, • M • lum ; pd, pellicle ; B, flagellar reser-
those who regard it as a family of voir. x eso. (After Goidschmiut.)
Infusoria. Since the discovery that
the equatorial groove of the Dinoflagellata (p. 182) is not ciliated, it
is usually regarded as a character of the class that true cilia do not
occur ; and if the vibratile processes of the Polymastigina are true
flagella, the only exception to this is to be found in the aberrant
genera Pteridomonas, Maupasia, and Monomastix (pp. 164 and 170).
As a rule, there seems to be no connection between the base of
the flagellum and the nucleus, but such a connection can be traced
i6o
THE MAST1GOPHORA
cst. --,
R.
in the genera Mastigamoeba and Mastigina, recalling the relation of
the axial filament to the nucleus in certain Heliozoa (p. 23).
At the base of the axial filament there is sometimes found a
minute granule, with peculiar staining properties, known as the
blepharoblast (Fig. 2, b), and closely associated with this there is
in the Trypanosomata l a small detached
portion of the nucleus known as the "kineto-
nucleus."
At the base of the flagellum there is often
found a special vacuole into which the con-
tractile vacuoles may or may not open (Figs.
1 and 2). This is the flagellar reservoir.
In some forms (Trichomonas and Trypanoso-
mata) a delicate undulating membrane is
found at one side of the flagellum (Fig. 2,
p. 195).
Besides the flagellate movements there are
two other important ways by which locomotion
can be effected by certain species, namely, by
amoeboid and by so-called metabolic or euglenoid
changes of shape, the former resulting in the
protrusion of pseudopodia, and the latter
involving alternate protraction and contraction
of the body, as may be observed in many
worms (Fig. 5 (28)).
The possibility of executing amoeboid and
ture of Copromonas. b, metabolic movements depends largely upon
blepharoblast; c.p, cyto- . » J ?
pharynx; c.st, cytostome ; the nature of the integument or pellicle which
/I,"' flageiuTm^6 /.»,aCfood- protects the protoplast from the surrounding
vacuoles; N, nucleus; R, fl,-,;/) rnpHium
flagellar reservoir. (After r lln-
Dobeii.) There are three principal kinds of integu-
ment, with many degrees of differentiation : —
1. Periplast. — This is an integral portion of the protoplast, from
which it is never separated and with which it divides. In naked
cells, such as Mastigamoeba, it appears as a simple ectoplasm covered
by a very thin pellicle (Fig. I, pel), or as an alveolar layer of proto-
plasm (Multidlia). In most cases there is a more or less well-
defined pellicle or plasmatic membrane, which may be distinguished
under the name of proteid-membrane. This achieves its highest
development in the Euglenoidea, where it often presents a spirally
striated structure and resists decomposition (Fig. 5 (16, 17)).
2. Perisarc. — The perisarc does not, as a rule, form an integral
part of the protoplast, and does not usually divide with it, so that
after the division of the protoplast one of the fission-products issues
1 For a discussion of the relations of these structures compare Dobell (3),
Minchin (13), Moore (14), Hartman and von Prowazek (5).
Fio. 2.
Diagram of the struc-
THE MASTIGOPHORA 161
from the perisarc as a naked cell. The protoplast is never com-
pletely adherent to its perisarc, but is capable of more or less
independent movement within it, and recedes from it upon the
formation of the resting-stage, and also in consequence of plasmo-
lysis. Its chemical composition is based upon a gelatinous substance
of carbohydrate nature, and in Dinobryon Klebs has found that the
perisarc gives the typical cellulose reaction.
The periplast is always present in Lissoflagellates, but the
perisarc is a secondary formation secreted by the protoplast through
the periplast, and may or may not be present.
The perisarc may occur as a capsule closely investing the cell
with an apical opening for the flagellum, as in Chrysococcus and
Trachelomonas. In the Chrysomonadine genera Synura, Mallomonas,
Hymenomonas, and Microglena the protoplast is closely adherent to
the perisarc, which here tends in the direction of a true cell-wall
and is called a cuticle. In Hymenomonas by exception the perisarc
divides with the cell.
The most familiar form in which the perisarc is developed is
that of a cupule, as in the calyptoblastic Hydroids. Well-known
examples of cupule-formation are presented by the genera Bicosoeca,
Poteriodendron, Salpingoeca (Fig. 7 (6, 7)), Dinobryon, etc. Some genera
secrete a stalk only, Avithout a cupule, of which AntJwphysa and
CephalotJwmnion are among the best-known examples.
3. 'Cell- Wall. — This stands in intimate relation with the proto-
plast, as in Algae and higher plants, so that the cell-body has no
independent movement, apart from the automatic streaming of
granules. The cell-wall may (Dinoflagellata) or may not (Volvo-
caceae and Coccolithophoridae) divide with the protoplast. Its
chemical composition resembles that of the perisarc, and in the Dino-
flagellata consists of cellulose. In the Coccolithophoridae the cell-
wall is built up of several shells
composed of calcium carbonate.
Nucleus. — The nucleus of the
Mastigophora shows many varie-
ties of intimate structure. In .A.
some cases the chromatin is dis-
tributed in the form of a simple
.chromatic network (Herpeto-
monas), in others (Bodo, Copro-
monas, Fig. 2) the chromatin is
nrptjpnr in flip fnrm nf n opnfril Two sta8es in the mitosis of the nucleus
mtrai of xoctnuca mmaris. A, archoplasmic body
lump Or maSS. In Eugkna there <a> becoming elongated previous to division ;
• •_..« i w> nucleus. B, the nucleus has wrapped round
IS Within the nuclear membrane the central part of the archoplasmic body, and
i , • i the chromosomes (ch) are approaching the
separate chromatin masses, and poies in rows. (After CWklm.)
in addition a substance which
has been variously interpreted, but is usually known as the
i62 THE MASTIGOPHORA
" nucleolar centrosome." In Noctiluca (Fig. 3) an archoplasmic
body situated outside the membrane accompanies the nucleus and
gives rise to the achromatic spindle of the mitotic figure. Mitotic
division of the nucleus has been described in a large number of
cases taken from all the principal divisions of the group, but itv is
certain that in some cases nuclear division occurs by amitosis
(Copromonas and others, Dobell [3]). Nuclear reduction in the for-
mation of the gametes has been observed in some cases (Trichomonas,
Bodo, Hexamitus, Copromonas, and others).
Notwithstanding the great variety of structure and mode of
division of the nuclei in the Mastigophora, there is no evidence that
in any case a division of the nuclear substance takes place into a
somatic nucleus and sexual nucleus, comparable with the mega-
nucleus and micro-nucleus of the Infusoria (Heterokaryota). The
separation of the kineto-nucleus from the main nucleus in the
Trypanosomata may suggest that in this case there is a delegation
of special functions in connection with the flagellum to a detached
portion of the nucleus ; but apart from this all the Mastigophora
are in the strictest sense Homokaryota (Hickson).
The life -history of the organisms comprised by the class
Mastigophora shows so many varieties that no general principles
can be laid down in this place. The life-histories of several forms
are described in the account given of the various subdivisions of
the group. The great advance in our knowledge of these forms
that has been made during the past few years suggests that a
process of gametogenesis followed by conjugation of the gametes
occurs in the life-histories of all the orders.
The Mastigophora are an important component of the micro-
plankton of oceanic and lacustrine waters. The Dinoflagellata
together with the Algae of the natural order Bacillariaceae, to which
the former appear to be more or less closely related, are said to
constitute the bulk of the primary food-supply (Urnahrung) of the
sea [Schiitt],
It is customary, in the more recent treatises, to employ the
term Flagellata in a restricted sense, equivalent to the Lissoflagellata
of Lankester, with the inclusion of the Choanoflagellata. In this
sense also the term Euflagellata has been employed, and the
flagellate members of the freshwater plankton comprise Euflagellate,
Dinoflagellate, and Phytoflagellate l forms. The marine plankton
comprises in addition the Cystoflagellata and the Coccolitho-
phoridae.
It is in order to avoid possible confusion that the term Mastigo-
phora, introduced by Diesing in 1866, is employed to designate the
entire group of flagellate organisms.
1 Sometimes the Phytoflagellata are comprehended within the Euflagellata, but
this tends to misapprehension.
THE MASTIGOPHORA 163
The six sub-classes of Mastigophora may be tabulated as
follows : —
Sub-Class 1. Lissoflagellata ) -,-, a ,, ,
«, > Luflasjellata.
„ 2. Choanoflagellata j
„ 3. Phytoflagellata (Volvocaceae).
„ 4. Dinoflagellata (Peridiniales).
,, 5. Cystoflagellata.
,, 6. Silicoflagellata.
The Euflagellata are defined as Protozoa which possess a sharply
defined, uninuclear sarcode, whose periplast is either a simple
ectoplasm or a definite pellicle. During the greater portion of
their life they are in motion, or at least capable of motion. They
have a definite anterior end, from which one, two, or many flagella
arise, and they possess one contractile vacuole or several. Repro-
duction takes place by simple longitudinal fission,1 generally in the
flagellate condition, sometimes in a resting condition. It seems
probable that most of the Euflagellata are capable of forming
resistent cysts, usually called sporocysts.
The occurrence of a process of conjugation was asserted by
Dallinger and Drysdale and others of the earlier observers, but
some doubt was thrown upon the accuracy of these statements by
Biitschli and Senn. In recent years, however, the formation of
definite gametes and a process of conjugation have been proved
to occur in Mastigella by Goldschmidt (4), in Pseudospora by
Kobertson (18), in Monas and Bodo by von Prowazek (16), in
Copromas by Dobell (3), and in Trypanosoma and other forms by
Schaudinn (19). There seems to be little doubt, therefore, that
conjugation is a normal process in the life-history of all the
Euflagellata.
SUB-CLASS I. LISSOFLAGELLATA, Lankester.
The members of this sub-class are distinguished from the other
Euflagellata by the absence of a collar. The sub -class is divided
into the three orders :
1. Monadidea.
2. Euglenoidea.
3. Chromomonadidea.
ORDER 1. Monadidea, Biitschli.
The Monadidea comprise the least differentiated forms of
Mastigophora, and include genera that exhibit affinities with the
Proteomyxa (Multicilia, Pseudospora, p. 8), with the Lobosa (Rhizo-
1 Cases of true transverse fission are very rare among the Lisso- and Choano-
flagellates ; e.g. Oxyrrhis, Stylochrysalis, Phalansterium.
164
THE MASTIGOPHORA
mastigoda), and possibly also with the Heliozoa (Dimorpha). They
are colourless Flagellata with one to an indefinite number of flagella,
a simple vacuole system, and usually a single nucleus. Their
nutrition may be holozoic, parasitic, or saprophytic, but probably
never holophytic.
TRIBE 1. PANTOSTOMATINA, Seun.
Solid foodtmay be ingested at all points in an amoeboid fashion.
StrB-TRiBE 1. HOLOMASTIGODA, Lauterborn. With polyaxonic body,
flagella scattered all over the surface, pseudopodial ingestion of food, loco-
motion rotatory, defaecation at all points.
Multicilia, Cienkowski ; M. marina, Cienk., with one nucleus ; M.
lacustris, Lauterborn, plurinuclear, the only instance of the kind among
Mastigophora. The genus Grassia, Fisch., closely allied to Multicilia, is
found in the alimentary canal of the frog and in the blood of Hyla.
SUB-TRIBE 2. KHIZOMASTIGODA, F. E.Schultze. With one or two flagella,
natant and amoeboid or heliozooid phases. The flagella persist through
the amoeboid or heliozooid phase. The monomastigote and dimastigote
genera present a parallel series, and in addition there is an aberrant genus.
Pteridomonas, Penard, in which there is a circlet of 8-12 cilia, which can
be rolled inwards like a watch-spring and then bent outwards, exerting a
jerking action by which the animal hops backwards.
These cilia surround the base of the single main
flagellum.
In the genus Mastigamoeba the flagellum arises
directly from the nucleus. The genus Mastigina
(Frenzel) is closely related to Mastigamoeba, but the
body is covered with a thick pellicle. The position
of Mastigella, Frenzel (Fig. 4), is more difficult to
determine, as there may be one or more flagella
which are quite independent of the nucleus. In
Mastigamoeba schulzei (Frenzel) and Mastigina setosa
(Goldschmidt) the body is thickly beset with long
rigid bristles which have the general appearance
of cilia, but seem to have the same nature as the
adhesive granules (Klebkdrner) with which the
pellicle and superficial ectoplasm of several species
of the three genera are provided. It is possible
that they are of the same nature as the spicules
of the ectoplasm found in several of the Lobosa
Mastigella vitrea, Gold- (Trichosphaerium, etc.) and some of the Heliozoa
schmidt. OneoftheRhizo- ) 2 ' ~n ao\
mastigoda. Active form. (Heterophrys (ct. pp. 23, 68).
c.», contractile vacuole ;
/. portions of filamentous m, i-r v» i. r -nr , • 77 • , • i
algae ingested as food ; fl, Ine liie-nistory of Mastigella vitnna has
ScTmidto250- (After recently been fully investigated by Gold-
schmidt (4). During the vegetative life of
this animal a series of binary fissions occur which are preceded
by a withdrawal of the pseudopodia and flagellum and a mitotic
Fio. 4.
THE MASTIGOPHORA 165
division of the nucleus. The number of chromosomes seen in these
mitotic divisions is about 40, and there are no centrosomata at
the poles of the spindle. The sexual reproduction is preceded
by the formation of mega- and microgametocytes. In the early
stages the gametocytes cannot be distinguished from the ordinary
vegetative individuals except as regards the microscopic character
of the nuclei. A number of minute granules of chromatin
(chromidia or sporetia of Goldschmidt) are extruded from the-
nucleus, increase in number and size, and give rise to the nuclei
of the numerous gametes. The cytoplasm of the gametes is
formed by a differentiation of clear protoplasm around each
nucleus. In the case of the formation of the megagametes at least
one mitotic division of the nucleus occurs, which has been inter-
preted to be a polar division. A similar polar division of the
nucleus probably takes place also in the formation of the micro-
gametes. The elements of these nuclei are so small that it has
not been proved that a definite reduction in the number of the
chromosomes occurs. In both kinds of gametocytes an encystment
accompanied by withdrawal of the pseudopodia and flagella occurs,
but the microgametocyte encysts sooner than the megagametocyte.
The gametes escape from the gametocytes and conjugate to form
a zygote. The megagametes are about 3-6 /* in diameter and
are provided with a single flagellum 15-18 /A in length. The micro-
gametes are 2-8 /* in diameter and are also provided with a
flagellum. The zygote is a minute active monad, which divides
several times by simple fission and then grows and assumes the
general characters of the genus.
The principal genera are : — Amoeboid and monomastigote : Mastiga-
moeba, Schulze ; Mastigella, Frenzel ; Mastigina, Frenzel. Amoeboid and
dimastigote : Cercobodo, Kent = Dimastigamoeba, Blochmann, and some of
the species attributed to the genus Cercomonas (Fig. 5 (32, 33)). Heliozooid
and monomastigote : Actinomonas, Kent. Heliozooid and dimastigote :
Dimorpha, Gruber.
TRIBE 2. PROTOMASTIGINA (sensu stricto).
Solid food is ingested at a fixed point near the base of the flagellum.
SUB-TRIBE 1. MoxoMASTiGODA.1 A. Flagellum directed forwards,
a. Oicomonas, Kent (Fig. 5 (29, 30, 31)). Ingestion of food at base of
flagellum by means of a protuberant vacuole (vacuolar ingestion) which
subsequently migrates to the posterior end. /3. Leptomonas, Kent. Rod-
shaped or fusiform, parasitic in intestine of insects. B. Flagellum
directed backwards, a. Ancyromonas, Kent. The single flagellum arises
at anterior end, but is bent backwards and serves as an anchor or
1 Tdis sub-tribe comprises the Cercomonadina of Saville Kent or the Oicomona-
daceae of Senn. From the work of Klebs and others it seems necessary to reject
the genus Cercomonas, since the confusion surrounding it cannot lie lightened.
THE MASTIGOPHORA 167
gubernaculum as in Bodo. Marine. (3. Phyllomonas, Klebs. A triangular,
contorted, foliaceous monad with the flagellar pole directed backwards
in locomotion ; the flagellum acts therefore as a pulsellum. Stagnant
water. C. Sessile, calyptoblastic genera, a. Codonoeca, Clark, constructs
a pedunculate, ribbed, colourless theca in which it resides freely.
Freshwater and marine. (3. Platytheca, Stein, constructs a membranous
encrusting theca.
The Family TRYPANOMORPHIDAE, containing the single genus Try-
panomorpha, Woodcock, belongs to this sub-tribe. A full description of
this form is given in Section G, p. 193.
Fio. 5.'
1, Chlamydomonas pidvisculus, Ehrb. ; one of the Phytoflagellata ; free-swimming indivi-
dual ; a, nucleus ; bb, contractile vacuoles ; c, pyrenoid ; d, cellulose investment ; e, stigma
(eye-spot). 2, resting-stage of the same with fourfold division of the cell -con tents ;
letters a> before. 3, a cyst that has been formed by the conjugation of gametes and is now
liberating a large number of minute biflagellate zooids. 4, Synerypta volvox, Ehrb. ; one of the
Chrysomonadina. A colony enclosed by a mucilaginous test(c). a, stigma ; fr, vacuole. 5,Uroglen«
volvox, Ehrb. ; one of the Chrysomonadina. Half of a large colony. 6, Chlorogoniiim euchlorum,
Ehrb. ; one of the Phytoflagellata ; a, nucleus ; b, contractile vacuoles ; c, pyrenoids ; (?) d, eye-
spot. 7, the same species, showing conjugation of the gametes. 8, a colony of Dinobryon sertularia,
Ehrb. ; one of the Chrysomonadina loricata, x 200. 9, Sphaerella pal u stria, Girod ( — Haemato-
coccus fxilustris) ; one of the Chlainydomonudina ; ordinary individual with widely separated
test, to which it is attached by delicate strands of protoplasm, not shown in the figure ;
a, nucleus ; b, contractile vacuole ; c, pyrenoid. 10, dividing resting-stage of the same. 11, a
gamete of the same. 12, Phalansterium consociatum, Cienk. ; one of the Choanoflagellata, x 325.
Disk-like colony. 13, Euglena virulis, Ehrb. ; one of the Euglenina, x 300 ; «, pigment spot :
b, flagellar reservoir; c, paramylum granules; <l, chromatophores. 14, Gonium pectorale,
O. F. M. ; one of the Volvocina ; colony seen from the flat side, x 300 ; a, nucleus ; b, contractile
vacuole ; c, pyrenoid. 15, Dinobryon sertularia, Ehrb. ; one of the Chrysomonadina loricata :
a, nucleus ; b, contractile vacuole ; c, paramylum, (?) nucleus ; d, free colourless flagellates
probably not belonging to Dinobryon, ; e, stigma ; /, chromatophores. 16, Paranema tricho-
phorum, Ehrb. ; one of the Paranemina, x!40; a, nucleus ; 6, contractile vacuoles ; c, pharyn-
geal apparatus; </, mouth. 17, anterior end of Euglena acus, Ehrb., in profile ; a, mouth :
b, contractile vacuoles ; c, pharynx ; d, eye-spot ; e, paramylum bodies ; /, chromatophores.
18, part of the surface of Volvox globator, L., showing intercellular connective fibrils; a,
nucleus; b, contractile vacuole; c, pyrenoid. 19, two antherozooids (= microgametes) of
Volvox globator. 20, ripe asexually produced daughter individual of Volvox minor, Stein, still
enclosed in the cyst of the parthenogonidium ; a, young parthenogonidia. 21 and 22,
Undulina ranarum, E. R. L. (see Fig. 1, p. 194). 23-26, reproduction of Bodo caudatus, Duj. ;
one of the Heteromastigoda, according to Dallinger and Drysdale. 23, fusion of several indi-
viduals (plasmodium). 24, encysted fusion-product dividing into four. 25, later into eight.
26, cyst filled with swarm-spores. 27, Astasia tenax, O. F. M. ; one of the Astasiina, x 440.
Individual with two flagella and strongly contracting hinder end of the body ; o, nucleus ; 6,
flagellar reservoir. 28, the same devoid of flagella. 20, Oieomonas termo, Ehrb. ; one of the
Protomastigina, x 440 ; «, nucleus ; b, contractile vacuole ; c, food-inge>ting vacuole ; d,
food-particle. 30, the food-particle has now been ingested by the vacuole. 31, Oieomonas
mutahilis, Kent, with adherent stalk ; «., nucleus ; 6, contractile vacuole ; c, food-particle in food-
vacuole. 32, 33, Cereobodo (Cercomonas) crassicauda, Duj., showing two conditions of the
pseudopodium - producing tail ; a, nucleus ; b, contractile vacuoles ; e, mouth. (After
Lankester and various authors.)
SUB-TRIBE 2. PARAMASTIGODA. Solitary or colonial forms with one
long flagellum and one (rarely two) short accessory flagellum near its
base ; vacuolar digestion at the anterior end. A. Solitary genera.
JV/onas, Stein ; Sterromonas, Kent ; Physomonas, Kent. Freshwater.
B. Colonial genera. Cephalothamnium, Stein ; Anthophysa, Bory (Fig.
7 (12, 13)). Freshwater.
SUB-TRIBE 3. HETEROMASTIGODA. Solitary, colonial, free or attached
forms with at least two flagella of different kinds, of which one is
directed forwards and another is directed backwards, acting as a
gubernaculum or steering flagellum in the free forms or as a stalk of
attachment in the fixed forms. A. Free solitary and naked genera (Bodo-
nina, Biitschli) ; Bodo (Fig. 7 (10)), Ehrenberg — freshwater and marine ;
1 68 THE MASTIGOPHORA
Pleuromonas, Perty ; Phyllomitus, Stein ; Colponema, Stein ; Rhynchomonas,
Klebs ; Oxyrrhis (Fig. 10 (2)), Duj. — marine. Bodo can execute character-
istic jumping movements by means of the gubernaculum. It captures
its food (bacteria and infusoria) and sucks out the protoplasmic contents
by means of a rostral process (rostral ingestion). According to Dallinger
and Drysdale a process of plasmodium- formation occurs in this genii?,
followed by encystment and subsequent division of the protoplasmic
contents into numerous swarm-spores (Fig. 5 (23-26)). In Oxyrrhis there
is a large oral funnel and a rudimentary pharynx similar to that of the
Euglenoidea. This genus is said to divide transversely instead of
longitudinally as in all other Heteromastigoda. The genus Costia
(Leclerq) with three flagella, reposing in a groove when at rest, may
belong to this sub-tribe (see p. 157). B. Sedentary and usually colonial
forms, protected by a cup-shaped or closed theca and attached to the
base of it by the gubernaculum. At the anterior extremity there is a
plate-like expansion of the ectoplasm (the peristome). (Bikoecina, Stein) ;
Bicosoeca, Clark, solitary or in rosettes ; (B. socialis, Lauterborn).
Peristome thin and membranous. Freshwater and marine. Poterio-
dendron, Stein, fixed, " dinobryoid " association of stalked thecate
individuals ; peristome thick, proboscis-like.
The Bikoecina appear to suggest a transition from the Lissoflagellata
to the Choanoflagellata in virtue of their peristome, which is perhaps
comparable to the collar.
The Family TRYPANOSOMATIDAE, containing the blood-parasites Try-
panophis, Trypanoplasma, and Trypanosoma, belong to this sub-tribe.
The family is fully described in Section G, p. 193.
SUB-TRIBE 4. ISOMASTIGODA. Monaxonic body with two equal
flagella at the anterior end. A. Solitary (Amphimonadina). Amphimonas,
Duj. ; Streptomonas, Klebs ; Diplomita, Kent. Freshwater. B. Colonial
(Spongomonadina). Numerous individuals united "in a common jelly
or in branched gelatinous tubes, the end of each of which is inhabited by
a single and distinct individual." l Spongomonas, Stein ; Cladomonas,
Stein ; Rhipidodendron, Stein. Diplomita (Kent) is now regarded as an
individual of Spongomonas living isolated in the theca of a Bicosoeca. All
freshwater.
An interesting Protozoon which is known by the name of
Pseudospora volvocis, Cienkowski, and was placed by Biitschli in the
tribe Isomastigoda, is found parasitic upon Volwx. According to
Robertson (18), it has three forms, each from 12 to 30 /x in diameter.
A, an amoeboid form ; B, a pear-shaped flagellate form, with two
flagella at one end ; C, a spherical Actinophrys-like form. In each of
these forms there is a single definite nucleus containing a centrally
placed karyosome surrounded by clear nucleoplasm. The amoeboid
form feeds by ingesting individuals of the Volwx colony, and it
gives rise to the flagellate form, which swims away and attacks
another colony. Reproduction of the amoeboid form occurs
1 Lankester, E. R., Enci/. Brit., 9th Ed., Art. "Protozoa."
THE MASTIGOPHORA 169
accompanied by a definite mitotic division of the nucleus.
Alternation of the amoeboid and flagellate forms with reproduction
by fission continues for about eighteen days, and then gameto-
genesis sets in. The gametes are minute (1-2 p, in length) uni-
fiagellate organisms, and soon after their escape they conjugate in
pairs to form the zygotes. Gametogenesis occurs in the amoeboid
form, without encystment or withdrawal of the pseudopodia, and the
number of gametes formed by a single individual may exceed one
hundred. After a time the zygotes withdraw their flagella, assume
a spherical shape, and then creep into a Volwx individual.
Gametogenesis may also occur in the radial form, but it has not
been observed in the flagellate form.
It does not seem to be certain that the species described belongs
to the same genus as others that have been attributed to Pseudospora
(see p. 8), but the description of its life-history given by Miss
Robertson proves that it is not a Proteomyxan, but is correctly
placed with the Mastigophora.
TRIBE 3. POLYMASTIGINA.
With more than two flagella (exclusive of Multicilia).
SOB-TRIBE 1. TRIMASTIGINA. Three flagella. Trimastix, Kent ;
Dallingeria, Kent ; Elvirea, Paroiia. Costia necatrix, Henneguy, is a
flagellate ectoparasite of the trout which cannot live in infusions, but
requires very pure water. It is the only flagellate ectoparasite known
which cannot live apart from its host. It penetrates into the epidermis
of the fry, frequently causing a mortal disease. The adult fishes are
immune, being protected from the parasite by their scales.
SUB-TRIBE 2. MoxosiOMATiNA.1 Four (rarely six) flagella, one
mouth-spot or oral groove, unilateral, asymmetrical. Tetramitus, Perty
(Fig. 7 (14)); Collodictyon,C&i'teT; Trichomonas, Donne" ; Trichomastix^loch-
mann ; Monocercomonas, Grassi ; Megastoma, Grassi. Megastoma entericum,
parasitic in man and domestic animals, is regarded as intermediate
between the Tetramitina and the Distomatina (Klebs), having a uni-
lateral mouth as in Tetramitus and sextuple flagella as in Hexamitus.
Trichomonas, Donne. T. intestinalis is found in the intestine of mice.
" It is pear-shaped with three flagella springing from the blunt end, and
an undulating membrane with a thickened border passing in a spiral
manner round the body and terminating in a free flagellum " (Wenyon).
SOB-TRIBE 3. DISTOMATINA, Klebs, 1892. Body bilateral but not
symmetrical, since the two mouth-spots (oral grooves) are placed on
opposite surfaces of the body ; flagella arranged in pairs. Principally
found in stagnant water. Gyromonas, Seligo, 4 flagella ; Trigonomonas,
Klebs, 6 flagella ; Trepmnonas, Duj., 8 flagella ; Hexamitus, Duj. (Fig. 7
(5)), and Urophagus, Klebs, with 6 or 8 flagella, of which two or three
pairs are anterior and the fourth pair are gubernacula (Schleppgeisseln).
The two last-named genera are, alone among Flagellata, characterised by
1 Including the Tetramitina, with a wider significance.
iyo THE MASTIGOPHORA
forming, as products of metabolism, glycogen-like bodies (Klebs). H.
muris is found in the intestine of mice (Wenyon). Lamblia intestinalis
is found in the intestines of various mammals, and is not infrequently
parasitic in man. It is not thought to be pathogenic. Spironema, Klebs.
Polymastigote ; flagella arising in pairs at the margins of the spiral
mouth-grooves.
SDB-TRIBE 4. LOPHOMONADINA, exclusively parasitic in the rectum of
insects. This sub-tribe is regarded by some authors as having closer
affinities with the Ciliata. It has already been described under the
heading Family Trichonymphidae in Fasc. II. p. 417 of this Treatise.
The genus Maupasia (Schewiakoff) has the anterior part of the body
covered with cilia, but at the posterior end it bears a long flagellum. By
some authors it is regarded as a Polymastigine flagellate, but its affinities
seem to be with the Ciliata. Freshwater. Hawaii. Monomastix, Roux, is
another genus with a polar flagellum and cilia in longitudinal rows.
There are said to be two meganuclei and two micronuclei. This genus
should also be included in the Ciliata.
ORDER 2. Euglenoidea.
The second order of Lissoflagellata comprises the most highly
organised members of the sub-class. This high degree of special-
isation is indicated by the structure of the pharyngeal armature of
the tribe Peranemina, which consists of two converging rods, which
can be protruded from the base of the oral funnel.
With regard to the nutrition of Mastigophora as a class, to
which allusion has already been made, it is necessary, even from a
purely systematic standpoint, to consider (1) the nature of the
food ; (2) the mechanism of ingestion ; (3) the products of meta-
bolism. In holozoic nutrition the food consists of bacteria, other
monads, swarm-spores of Algae, starch, and the like. The modes
of ingestion by which these food-bodies are conveyed into the pro-
toplast of the feeding organism are of five principal kinds, namely,
pseudopodial ingestion (Pantostomatina) ; vacuolar ingestion (Mono-
mastigoda, Paramastigoda, Isomastigoda, Choanoflagellata) ; rostral
or suctorial ingestion (Heteromastigoda) ; stomatic ingestion, by
which the food sinks into the protoplasm through one (Monostoma-
tina) or two (Distomatina) points of least resistance situated in one
or two depressions (oral grooves) below the insertion of the flagella ;
pharyngeal ingestion (Peranemina).
Not only does the mode of feeding distinguish the Peranemina
from all other Flagellata, but they are further distinguished by
their well-marked, spirally striated periplast or cuticula. In the
Euglenoidea the periplast is generally a striated, resistent proteid-
membrane.
The vacuole-system of the Euglenoidea consists of a non-con-
tractile or feebly contractile reservoir provided with an excurrent
THE MAST1GOPHORA 171
canal opening at the apex of the cell, and one or many accessory
contractile vacuoles discharging into the reservoir (Fig. 5(17)). A
similar kind of compound vacuole-system is also met with among
the Peridiniales (Fig. 12).
The products of metabolism which occur in the Euglenoidea
consist of fatty oil and paramylum, a substance allied to starch, but
not giving the typical starch-reaction. It is interesting to note that
the saprophytic Euglenoids of the tribe Astasiina, which are destitute
of chlorophyll, none the less produce paramylum.
The Euglenoidea include holozoic, holophytic, saprophytic, and
mixotrophic species, and one of the most characteristic properties
which they have in common is the formation of paramylum as the
principal product of metabolism.
This order presents a series of forms analogous to the Mona-
didea in regard to the distribution of the flagella : monomastigote
forms (JEuglena, Peranema, dstasin) ; paramastigote (Distigma,
Sphenomonas, Tropidoscyphus) ; isomastigote (Eutreptia) ; and, finally,
heteromastigote forms (Heteronema, Dinema, Anisowma).
The Euglenoidea are divisible into two sections and three tribes.
A. Without special pharyngeal apparatus.
TRIBE 1. EUGLENIXA.
Holophytic. A red stigma or eye-spot close to the vacuole is present,
.iind green chromatophores.
Euglena, Ehrb. (Fig. 5 (13, 17)) ; Colacium, Ehrb. ; Lepocinclis, Perty ;
Trachelomonas, Ehrb. ; Eutreptia, Perty ; Ascoglena, Stein ; Cryptoglena,
Ehrb. Trachelomonas is sometimes found in the sea ; the others are
freshwater forms.
TRIBE 2. ASTASIINA.
Saprophytic, without chlorophyll. Astasia (Fig. 5 (27, 28)), Duj. ;
Distigma, Ehrb. ; Sphenomonas, Stein ; Menoidium, Perty ; Rhabdomona.*,
Fresenius ; Atractonema, Stein. All freshwater forms.
B. With special pharyngeal apparatus.
TRIBE 3. PARANEMINA.
Holozoic.
a. With one flagelluin. Paranema (Fig. 5 (16)), Duj. ; Euglenopsis,
Klebs ; Urceolus, Meresch. ; Petalomonas, Stein ; Scytomonas, Stein. All
found in fresh water, but Euglenopsis flourishes in vegetable infusions.
•Copromonas, Dobell (3), parasitic in intestine of frogs.
(3. With two flagella. Heteronema, Duj. ; freshwater and marine.
Dinema, Perty ; stagnant freshwater. Zygoselrnis, Duj. ; freshwater. Tropi-
doscyphus, Stein ; freshwater; Anisonema, Duj. ; freshwater Entosiphon,
Duj. ; marine and freshwater.
172 THE MASTIGOPHORA
One of the commonest of the Euglenoidea is Euglena viridis, a
species which is frequently found in shallow ditches and puddles,
giving the water a green tint or forming a green scum on its-
surface. The free -swimming individuals are about O'l mm. in
length, provided with a single flagellum arising just in front of a
short funnel-shaped cytostome at the pointed anterior end of the
body. Opening into the cytostome funnel there is a small reservoir,
which itself receives the fluids discharged by a system of minute
contractile vacuoles. The chlorophyll is present in the form of
numerous minute chloroplasts, and the paramylum in the form of
many minute plates. At the base of the flagellum there is a red
eye -spot composed of numerous granules of " haematochrome."
There is a single nucleus. An important phase in the life-history
is the resting stage. The individuals swarm to the surface of the
water, where they form the green scum. Each individual in the
scum loses its flagellum, and, secreting a gelatinous substance
which joins with that of its neighbour's to form a continuous jelly,,
encysts.
Division of the nucleus and cell-substance takes place during
the resting stage at night. The mi to tic changes commence about
two hours after dark and are completed in five hours. The
nucleus has in the resting stage a centrally placed " nucleolo-
centrosome." This becomes dumb-bell-shaped and then elongates-
in mitosis. The chromosomes become parallel to this body, and
eventually form an equatorial ring round it. In this position they
undergo longitudinal splitting (Keuten).
Euglena undergoes several successive divisions under the same
cyst-membrane, forming quadrants, octants, etc., but all result from
successive longitudinal division, unlike the ciliate infusorian Colpoda,.
which produces similar clusters resulting from successive cross-
division. Again, in the Volvocines the clusters arise by alternate
longitudinal and transverse division (Klebs).
Thus, in the case of Euglena and Copromonas, division takes-
place after the loss or withdrawal of the flagellum, but in the allied
Astasiina division takes place during the motile phase.
Euglena gracilis occurs in both green and colourless conditions,
so that, employing Pfeffer's terminology, it may be at one time
autotrophic (holophytic), at another time heterotrophic (sapro-
phytic), the two conditions being connected by a mixotrophic
transition.
An important contribution to the life-history of the Euglenoidea
has recently been made by Dobell (3). In Copromonas subtilis, from
the intestine of the common frog and toad, reproduction is effected
by simple longitudinal fission accompanied by amitotic division of
the nucleus. After a period of from two to six days a considerable
number of individuals are found to be conjugating. All the
THE MASTIGOPHORA 173
individuals appear to be facultative gametes and there is no sexual
differentiation. During the conjugation the nucleus of each of the
conjugants divides at least once, one of the daughter nuclei thus
produced, being a polar nucleus, degenerates in the cytoplasm and
is lost. The remaining nucleus of each conjugant fuses with its
fellow to form the nucleus of the zygote. It should be stated that
after the first division of the nuclei of the conjugants small granules
of chromatin are protruded from the central chromatin mass and
are lost in the cytoplasm (heteropolar division). The zygote
behaves exactly like an ordinary individual and divides soon after
it is formed by longitudinal fission in the ordinary manner.
ORDER 3. Chrcmomonadidea.
This is the first of the groups of Mastigophora that are regarded
by many authors as belonging to the vegetable kingdom ; for,
although there is an active free- swimming stage of life, the method
of nutrition appears to be in all cases holophytic. In the Chloro-
monadina, which may be regarded as in many respects intermediate
between this order and the other Lissoflagellata, there is a funnel-
shaped depression at the base of the flagellum ; but this does not
serve the purposes of a mouth, but is an excretory duct of the
contractile vacuole reservoir. In the other tribes of the order
even this vestige of the Lissoflagellate mouth is lost. The Chloro-
monadina also resemble the Euglenoids in having the chlorophyll
scattered through the endoplasm in minute chloroplasts. No
process of conjugation has yet been observed in this order. Among
the Chrysomonadina, Chrysamoeba has the ordinary form of a
flagellate organism when it is actively swimming, but when it
comes to rest it protrudes delicate radiating pseudopodia and
resembles a Mastigamoeba.
Chromulina rosanoffi, according to Woronin (23), forms a scum of
encysted individuals at the surface of ponds in Finland. This
gives rise to the flagellate swarm-spores which after a time penetrate
the cells of Spirogyra and again encyst. In Dinobryon the indi-
viduals are attached to the base of an open receptacle. They
usually occur in dense spreading free-swimming colonies (Fig. 5 (8)).
Reproduction is by fission or by the formation of spherical cysts
which escape from the receptacle and start new Dinobryoid colonies.
Syncrypta (Fig. 5 (4)) forms globular colonies invested by a
mucilaginous test through which the flagella protrude. Uroglena
also forms globular colonies, but the flagellate individuals are at the
periphery and the centre is filled with mucilage.
The genera comprised in this order are freshwater in habit,
except the Coccolithophoridae, which are exclusively marine.
The order is divided into three tribes : —
174 THE MAST1GOPHORA
TRIBE 1. CHLOROMONADINA, Klebs.
The body is naked, the periplast consisting of a smooth non-resistent
membrane formed by a thick layer of ectoplasm, in place of the in-
tegument of the Euglenoids. The chloroplasts are generally numerous
and the vacuole-system is compound, resembling that of the Euglenoids.
The product of metabolism is neither starch nor paramylum, but fatty
oil. There is a funnel-shaped depression at the base of the flagellum
corresponding with the cytostome, but not used for the ingestion of food.
Genera — Facuolaria, Cienkowski ; Coelomonas, Stein; Raphidomonas,
Stein.
TRIBE 2. CHRYSOMONADINA, Biitschli.
The members of this tribe resemble the Protoinastigina, with the
addition of chromatophores which carry a yellowish-brown pigment called
chrysochrome, allied to diatomin. The chrysochrome-plates are usually
two in number, placed right and left. They do not contain pyrenoida
and do not manufacture starch. There is a red stigma (eye-spot). The
products of metabolism are fatty oil and a refringent soluble proteid
called leucosin (Klebs).
Nutrition is generally holophytic ; there is no mouth ; generally two
flagella.
The tribe is divided by Klebs into three sections or sub-tribes : —
A. CHRYSOMONADINA NUDA.
Chrysamoeba, Klebs ; Chromulina, Cienkowski ; Ochromonas, Vyssotzki ;
Stylochrysalis, Stein. The last-named is attached to colonies of Eudorina.
B. CHRYSOMONADINA LORICATA.
Dinobryon, Ehrenberg (Fig. 5 (8, 15)) ; Hyalobryon, Chi-ysopyxis, Ehrb.;
Chrysococcus, Klebs ; Cyclonexis, Senn.
The researches of Lohmann (11) have shown that the family
Coccolithophoridae must be included in this group.
The members of this family are extremely minute organisms,
of which the largest species are only 25-50 p. in diameter, found in
the plankton of the sea and characterised by the possession of
a theca composed of minute calcareous shells which have long
been familiar to zoologists under the names "coccoliths" and
" rhabdoliths."
The organism bears one flagellum or two equal flagella, a single
nucleus, two (rarely one) large green or brown chromatophores,
each containing a drop of a substance which appears to be oil
(Fig. 6, D), and in many cases a vacuole situated near the base of
the flagellum. The body is surrounded by a soft membrane which
supports the theca of calcareous shells. The shape of the shells
that compose the theca shows immense variety in the family. Two
THE MASTIGOPHORA
'75
kinds have been distinguished, those that are imperforate (discoliths,
lopadoliths, calyptroliths), and those that have a central perforation
(Fig. 6, B) (placoliths and rhabdoliths). The significance of the per-
foration in the placoliths and rhabdoliths is not clear, but there is
no evidence at present that it transmits protoplasmic processes from
the ectoplasm.
When the theca is once formed it is never increased in size by
the addition of new shells, but when the growth of the organism
B
G.
FIG. 6.
To illustrate the structure of the Coccolithophoridae. A, Scyphosphaera apsteini, Lohmann,.
X 2000. (j, a girdle of peculiar enlarged coccolitlis. B, optical vertical section of an example
of a perforated coccolith of Coccolithrrpora Irptopora, M. and B. C, side-view of a simple collar-
shaped imperforate coccolith of Calyptrosphaera oblonga, Lohmann. D, vertical section of
Pontosphuera haeckelii, Loh. ; co, the sheath of coccolitlis ; ch, the two chromatophores', eacli
containing a highly refractive globule ; /, the flagellum ; n, the nucleus. B, side-view of one
of the coccolitlis of the same species. F, Discosphaera tubifer, M. and B. ; ch, chromatophores.
G, trumpet -shaped projection from the coccolith of Discosphaera tubifer, x 2000. '(After
Lohmann and Murray and Blackman.)
requires it, the theca is cast off as a whole and a new one formed
in its place.
Reproduction is usually effected by simultaneous longitudinal
fission of the theca and protoplasm, but occasionally large thecae
are found containing two individuals, indicating that fission of the
protoplasm may precede division of the theca or the formation of
two thecae.
No evidence has yet been obtained of the formation of gametes.
The Coccolithophoridae are exclusively marine, but are found
everywhere except in pure polar waters. They reach their greatest
numbers at a few fathoms from the surface.
176 THE MASTIGOPHORA
Sub-Family SYRACOSPHAERINAE. Pontosphaera (Fig. 6, D), Scypho-
sphaera (Fig. 6, A), Syracosphaera, and Calyptrosphaera — all described by
Lohmann.
Sub-Family COCCOLITHOPHORINAE, Lohmann. Coccolithopora, Loh. ;
Umbilicosphaera, Loh. ; Discosphaera, Haeck. (Fig. 6, F) ; Rhabdosphaera,
Haeck.
C. CHRYSOMONADIXA MEMBRANATA.
Mallomonas, Perty ; Synura, Ehrenberg ; Syncrypta, Ehrenberg (Fig.
5 (4)) ; Uroglena, Ehrenberg (Fig. 5 (5)) ; Microglena, Ehrenberg ; Hymeno-
monas, Stein.
TRIBE 3. CRYPTOMONADINA, Biitschli.
Coloured or colourless forms with one to three green chromatophores
or none. Nutrition is never holozoic and the product of metabolism is
starch, as in green Algae and in Dinoflagellata. The anterior end is
more or less obliquely truncate, usually with a deep frontal infundibulum l
like a peristome, from the side or bottom of which the two flagella arise.
Cryptomonas (holophytic), Ehrenberg ; Cyathomonas, Fromentel ; and
Chilomonas (saprophytic), Ehrenberg.
In Cryptomonas the colour of the chromatophores varies from green to
brown and yellow ; two are dorsal and one ventral. Cyathomonas possesses
no chloroplasts.
Closely related to the Cryptomonadina are the Phaeocapsaceae, contain-
ing the genera Phaeococcus, Borzi ; Phaeosphaera, West ; and Stichogloea,
Chodat. In these forms a large number of non-flagellate cells form a
mucilaginous investment ; but as the asexual reproduction takes place
principally during this phase of life, they are more usually regarded as
algae. The same may be said of the genus Hydrurus, Ag., in which the
cells are enclosed in a tough cylindrical mucilaginous envelope.
SUB-CLASS II. CHOANOFLAGELLATA, Saville Kent.
The Choanoflagellata are frequently regarded as constituting
a subdivision of the Protomastigina, a proceeding which is in
accordance with their affinities, though such is the singularity
of their form that it seems quite as appropriate to preserve their
independence as to merge them into a larger group. There are
no permanently free-swimming species, all are either sessile or
pedunculate, solitary or colonial. They can, however, quit their
.attachment temporarily and swim about with the collar directed
backwards. The collar may be defined as a special development
of the peristome surrounding the single flagellum which acts as a
pulsellum in locomotion. The collar is a contractile protoplasmic
process comparable in some respects to an undulating membrane.
The organism feeds by means of vacuolar ingestion, the food
1 Flagellar fundus. See also under Dinoflagellata, p. 187.
THE MASTIGOPHORA 177
particles being carried down on the outer surface of the collar, at
the base of which they sink into the body of the cell.
Several of the genera are found both in the sea and in fresh
water.
There are two orders of Choanoflagellata : —
ORDER 1. Craspedomonadina, Stein.
A. NUDA, Lankester.
Monosiga, Kent ; Diplosiga, Frenzel (with two collars, one within the
other) ; Hirmidium, Perty ; Codosiga, Kent (Fig. 7 (3, 4)).
B. LORICATA, Lankester.
Salpingoeca, Clark (Fig. 7 (1, 6, 7)); Polyoeca, Kent; Sphaeroeca,
Lauterborn.
ORDER 2. Phalansteriina ( = Gelatinigera, Lankester).
"The cell-units secrete a copious gelatinous investment and form
large colonies."
Phalansterium, Cienkowski (Fig. 5 (12)), with inconspicuous collars ;
Proterospongia, Kent (Fig. 7 (15)), with conspicuous collars.
SUB-CLASS III. PHYTOFLAGELLATA.
The Phytoflagellata or Volvocaceae are clearly related to the
Chromomonadidea, and some authors include this order in the sub-
class. Now that it has been definitely ascertained that conjugation
does occur in many of the Euflagellata, the formation of a zygote by
the copulation of two gametes is a feature that does not distinguish
the Phytoflagellata from the other sub-classes of the Mastigophora.
Moreover, although in Copromonas and some other Monadidea the
conjugating individuals cannot be distinguished from the asexual
individuals, definite micro- and megagametes are formed in the life-
history of Mastigella, Trypanosoma, and others. The phenomenon of
gametogenesis therefore is not a distinguishing character of the
sub-class. The Phytoflagellata, however, exhibit a much more
definite approximation to a purely vegetable structure than any
of the Euflagellata, and it may be convenient to keep them together
for the present in a separate sub-class.
The sub-class includes solitary and colonial forms, and the body
of the cell-unit is enclosed by a firm cell-wall which sometimes takes
the form of a bivalvate shell (Phacolus). In the colonial forms the
cell -units are embedded in a gelatinous matrix. There is no
indication of pharynx, nutrition being holophytic except in the case
of Polytoma, which is a colourless, saprophytic Chlamydomonad.
THE MAST1GOPHORA 179
There is usually a single large green chloroplast enclosing one
or more pyrenoids, and the product of metabolism is starch. The
vacuole-system consists, as a general rule, of two alternately con-
tracting vacuoles. There is a red stigma at or near the flagellar
basis. There are never less than two equal flagella, rarely four as
in Carteria and Pyramidomonas.
The Phytoflagellata are freslnvater in habit.
Among the organisms which are closely related to the Phytoflagellata,
but which are regarded in this volume as being just over the border-line
between the animal and vegetable kingdoms, we may include the families
Pleurococcaceae, Hydrodictyaceae, Protococcaceae, and Palmellaceae. The
genera Pleurococcus, Menegh., and Trochiscia, Kiitzing, belonging to the
Pleurococcaceae, have a more definite cell -wall and a more pronounced
FIG. 7.
1, Scdpingoeea fusiformis, Kent; one of the Craspedomonadina. The protoplasmic body is
drawn together within the goblet-shaped cell, and divided into numerous spores, x 1500.
2, escape of the spores of the same as monomastigote swarm-spores. 3, Codosigc vmlieUntii,
Tatem ; one of the Craspedomonadina. Adult colony formed by dichotomous growth, x 625.
4, a single zooid of the same, x 1250. a, nucleus; b, contractile vacuole ; c, the collar.
5, Hexam itux i/ijlutus, Duj. ; one of the Polymastigina, x 650. Normal adult showing (».) nucleus
and (6) contractile vacuole. 6, 7, Salpingoeca ttrceolata, Kent; one of the Craspedomonadina.
('>, with collar extended ; 7, with collar retracted within the stalked cupule. 8, Polytoma urvlln,
Miill. ; one of the Chlamydomonadina, x 800 ; «, nucleus ; 1), contractile vacuoles. P, Lopfcomowu
Mathirum, Stein ; one of the Polymastigina. 10, Bodo lens ; one of the Heteromastigoda, x 800 ;
K, nucleus; b, contractile vacuole; the wavy filament is a flagellum, the straight one is the
gubernaculum. 11, TetrutiiifH* .--iili'ittits, Duj.; one of the Polymastigiiia, x 430; a, nucleus;
ft, contractile vacuoles. 12, Anthophysu rryetans, O. F. M. ; one of the Paramastigoda, x 300.
A typical, erect, shortly-branching colony stock with four terminal monad clusters. 13, monad
fluster in same optical" section (x 800), showing the relation of the individual monads to the
stem (a). 14, Tetrniiutun /•«.-•/;•, itn.t. Ferty, x 1000 ; a, nucleus; b, contractile vacuole. 15,
Proterospongia haeckeli, Kent ; one of the Phalansteriina, x 800. A social colony of about forty
flagellate zooids. o, nucleus ; b, contractile vacuole ; c, amoebiform zooid sunk within the
common test ; c/, similar zooid multiplying by transverse fission ; e, normal zooids with their
collars retracted ; /, hyaline mucilaginous common test or zoothecium ; g, individual contracted
and dividing into minute flagellate spores (microgametes), comparable to the spermatozoa of a
sponge. (After Lankester and various authors.)
vegetative phase of life than SpJuierella, but in other respects are closely
related to it. The genus Hydrodictyon, Roth, forms a net-like coenobium
which floats at the surface of the water, and Fediastrum, Meyen, which
is also placed in the family Hydrodictyaceae, a flat plate-like coenobium
of cells that is protected by a thick and ornamented cell-wall. Among
the Protococcaceae such genera as Botryococcus, Kiitzing ; Tetracoccus,
West ; Ineffigiata, West, are probably closely related to some ancestral
form allied to tiphaerella ; but in some of the other genera, such as
Selenastrum, Reinsch ; Ankistrodesmus, Corda ; Dadylococcus, Nageli, in
which the cells are elongated and spindle-shaped ; and in Archerina,
Lankester 1 ; and Chodatella, Lemmermann, in which the cell-walls are
provided with long, stiff, bristle-like processes, there is a more pronounced
diversion from the Chlamydomonadine ancestry.
The family Palmellaceae has diverged from the same ancestry by the
development of a conspicuous envelope of mucilage, but it contains some
1 The genera Golenklnin, Chodat, Richteriella, Lemmermann, and Phytiielivs,
Frenzel, are probably the same as Archerina (see p. 33).
i8o THE MAST1GOPHORA
of the most primitive of the Chlorophyceous Algae. The principal genera
are Palmella, Lyngbye ; Palmodactylon, Nageli ; Sphaerocystis, Chodat ;
Schizochlamys, A. Br. ; Tetraspora, Link ; Apiocystis, Nageli ; Gloeocystu,
Nageli ; and Palmodictyon, Kiitzing.
ORDER 1. Chlamydomonadina.
Solitary forms in the flagellate phase.
In Chlamydomonas, which may be taken as an example of this
order, there are two flagella in the free-swimming stage, the body
is enclosed in a cellulose investment, there are two small contractile
vacuoles at the anterior end, a stigma (eye-spot), a single nucleus,
and one or more pyrenoids. Two individuals may conjugate and
form a zygote. The zygote encysts, the flagella being lost, and
the protoplasmic contents divide into as many as sixty-four cells
(Fig. 5 (3)) ; these cells escape as flagellate individuals similar in
general characters to the gametes, but instead of conjugating they
form a gelatinous investment, lose their flagella, and divide repeatedly
(the " palmella- stage "). From the gelatinous investment of the
colony that is thus formed the flagellate gametes ultimately escape.
Reproduction may also occur by the formation of a resting cyst and
the division of the cell-contents into two, four (Fig. 5 (2)), or eight
cells, which escape in a form like the parent.
The introduction into the life-history of this genus of a non-
flagellate " palmella-stage " during which growth and reproduction
take place has suggested that Chlamydomonas "is the phylogenetic
starting-point of the various lines of Chlorophyceous descent"
(Blackman and Tansley). That there is a strong resemblance
between the swarm-spores of many Algae and flagellate forms such
as Chlamydomonas cannot be denied, but the conclusion that all the
green Algae are descended from a flagellate ancestry is not universally
accepted (see West [22], p. 33).
Sphaerella, Sommerfeldt, 1824, is probably the correct generic name
for a very abundant organism found in rain-pools, water-butts, etc., that
is sometimes called Haematococcus, Agardh ; Chlamydococcus, Braun ; or
Protococcus, Huxley and Martin. The individuals may become brick-red
owing to the presence of " Haematochromin," and give rise to the
phenomena known as "red rain" and "red snow." The structure and
life-history of this organism are very similar to that of Chlamydomonas.
The infecting organism which forms the green cells in the Turbellariait
worm Convoluta roscoffensis is, according to Keeble and Gamble (7), a
Chlamydomonad allied to Carteria.
The principal genera are :
Carteria, Diesing, with four flagella ; Chlamydomonas, Ehrenberg ;
Sphaerella, Sommerfeldt (Fig. 5 (9, 10)) ; Haematococcus, Agardh ; Polytoma,
Ehrenberg (Fig. 7 (8)) ; Chlorogonium, Ehrenberg (Fig. 5 (6)) ; Pyramimonas,
Schmarda.
THE MASTIGOPHORA 181
ORDER 2. Volvocina.
Individuals biflagellate, arranged in colonies called "coenobia,"
of definite forms, with a gelatinous matrix. Reproduction takes
place by the cleavage of certain individuals (cells) of the colony
called the gonidia. There are two kinds of gonidia — the partheno-
gonidia or asexual forms, and the gametogonidia or sexual forms.
The gametogonidia consist of the oogonidia or female gametes and
the antherogonidia or spermatozooids. These conjugate to form
the zygotes.
The volvocine colony is physiologically an individual organism,
exhibiting histological differentiation and correlated locomotor
Activities of the constituent cells. In Eudorina the cells are
differentiated into male and female, the male cells arising from the
anterior quartet, the remainder becoming female. In Volvox the
reproductive cells, both parthenogonidia and gametogonidia, arc
limited to a few of the cells which compose the coenobium. In
Pleodorina the parthenogonidia are confined to the posterior
hemisphere (Fig. 9).
Protoplasmic intercellular connections between the cells (in-
dividuals composing the colony) only occur in the genus Volwx,
in apparent correlation with the high degree of individuation
attained by this form. Each cell or " coenocyte " is contained
within its own capsule, which is separated from neighbouring
capsules by a radial cell-wall. The sarcode is separated from the
cell-walls by a wide space which is occupied by the gelatinous
matrix, and protoplasmic processes radiate through the matrix and
traverse the cell-walls (Fig. 5 (18)).
The coenobium of Volvox is a sphere consisting of a single layer
of cells surrounding a central cavity, and thus presents a superficial
analogy to the blastula- stage in the embryonic development of
Metazoa. The presence of flagella, eye- spots, and contractile
vacuoles attest its animal properties, while the presence of
chromatophores, pyrenoids, and starch granules proclaim its
vegetable affinities.
The sphere comprises two differently constituted hemispheres.
The trophic hemisphere is that Avhich is directed forwards during
locomotion, and the component cells are distinguished by the
brighter development of the eye-spots. The other hemisphere is
the generative hemisphere, in which the oogonidia, antherogonidia,
and parthenogonidia are chiefly formed.
Locomotion is rotatory, i.e. forward progression accompanied by
rotation about the main axis either to the right or to the left,
though sinistral rotation is more frequent than dextral.
In Volvox globator, L., the average number of cells in a mature
coenobium is 10,000, the actual numbers ranging from a minimum
182
THE MASTIGOPHORA
of 1500 to a maximum of 22,000. In /'. aureus, Ehrb., the number
of cells varies from 200 to 4400. In a third species. V. tertius,
Meyer, intercellular protoplasmic threads are only present in young
unhatched colonies, not in the adult condition.
The form of the coenobium varies in the different genera.
Gonium, Miiller (Fig. 5 (14)) ; cells 4-16, arranged in a squarish plate
with flagella upon one face only ; envelope closely adherent. Stephano-
fphaera, Cohn ; cells 4-8, arranged in a rounded plate with flagella upon
one face only ; envelope swollen ; oval or spherical. Eudorina, Ehrb. ;
coenobium ellipsoidal or spherical ; cells 16-64, similar, not crowded nor
reaching towards centre. Pandorina, Bory ; coenobium ellipsoidal or
spherical ; cells 16-32, simi-
lar, crowded, reaching to-
wards centre ; outer mem-
brane or sheath of coero-
biuni showing characteris-
tic concentric stratification.
Platydorina, Kofoid (Fig.
8) ; coenobium horseshoe-
shaped, flat, one cell deep,
with 3-5 prolongations of the
gelatinous matrix at the pos-
FIG. 8. terior end ; cells 16 or 32 ;
Platydoniw. w.mlata, Kofoid. A plate-like Volvocine flagella upon both sides of
colony. The two surfaces of the colony are alike. .-, •, . ., ,, nlfpr.
The aspect of the adjacent cells alternates, so that l
the pole bearing the flagella and stignia of one 'cell natin". In side view the
is turned in the opposite direction to that of its im- , °. , ,
mediate neighbours, B, x. A, front view of the colony ; plate IS seen to be twisted
B, side view; C, a single cell showing, /, the flagella; cliahtlv in a Ipft sniral «r> at
T, the vacnoles \ *t, the stignia ; N, the nucleus ; and sllgntly !1
P, the pyrenoid. (After Kofoid.) to describe a figure of 8.
The asexual reproduction of
Platydorina has been observed by its discoverer (Kofoid, 1900) repeatedly
during five years, but sexual reproduction has not been seen in this genus.
All the cells are gonidial, each capable of dividing to form a daughter
coenobium. The daughter colonies acquire the adult form and torsion
before escaping from the maternal matrix, which then undergoes dis-
integration. Pleodorina, Shaw (Fig. 9) ; coenobium ellipsoidal ; cells 32,
arranged in 5 circles, 4 in each polar circle, 8 at the equator, and 8
in each intervening tract. Vegetative cells always 4 at the anterior
pole. Gonidial cells twice as large as the vegetative.
SUB-CLASS IV. DINOFLAGELLATA.
The Dinoflagellata or Peridiniales, formerly called Cilioflagellata
under an erroneous impression concerning the nature of the trans-
verse flagellum, are heteromastigote forms usually possessing a
complete cellulose membrane or cuirass which is never silicified.
The chromatophores are predominantly brownish coloured with a
THE MASTIGOPHORA
183
pigment known as peridinin. Eeproduction takes place by oblique
fission (Fig. 11) and by swarm-spores.1 There are two flagella
generally lodged in grooves, of which one traverses the latitude of
the body and the other the longitude. The former is called the
annulus or girdle and the transverse flagellum plies within it
(Fig. 10 (3)). The longitudinal groove is the sulcus harbouring the
longitudinal flagellum.
As already indicated, the Dinoflagellata constitute a very
important component of the freshwater and marine plankton, the
same generic forms occurring in both media. Moreover, they play
an important part in the physiology of oceanic life as a whole.
FIG. 9.
Pleoilorina illinoisensis, Kofoid. Colony of thirty-two cells. The four small cells at the
.interior pole are the vegetative cells (w), the remainder are facultative parthenogonidia,
pp. x 300. (After Kofoid.)
TRIBE 1. GYJINODIMACEAE.
There is no cuirass, but the grooves are present. The transverse
groove may be semiannular in extent and subcentral in position, with the
longitudinal fissure straight and nearly at right angles to it on the ventral
side (Hemidinium, Fig. 10 (1)) ; or the transverse groove may form a com-
plete ring subterminal in position passing into the ventral longitudinal
fissure, the anterior or prae-annular portion being much smaller than the
posterior and presenting the appearance of a rostrum (Amphidinium) ; again,
the annulus may be complete and occupy approximately the equator of the
cell, and the sulcus straight (Gymnodinium) ; finally, both annulus and
sulcus may have a spiral twist (Spirodinium, etc.).
1 Zederbauer (24) has described a process of the fusion of the protoplasm of two
individuals of Ceratiitm hirundinella which he regards as conjugation, but as the
further history of the zygote (?) has not been traced, it may be only of the nature of
plastogamic union such as we find in the Lobosa and Heliozoa.
1 84
THE MASTIGOPHORA
The genera thus fall into two groups : —
A. Annulus and sulcus simple, at right angles to one another, decus-
sating at one point, from which the two flagella take their origin.
Gymnodinium, Stein. Freshwater and marine. Hemidinium, Stein
(Fig. 10 (1)). Freshwater. Amphidinium, Clap, and Lach.
FIO. 10.
1, Diagram of Hemidinium, one of the Dinoflagellata; 71, nucleus; /, flagellum of the
transverse groove ; h, flagellum of the vertical groove. 2, diagram of Oxyrrhis, one of the
Heteromastigoda (to compare with the preceding); n, nucleus; g, the deep fossa or pit in
which the two flagella are affixed ; t, the origin of the flagellum, which corresponds with that of
transverse groove of Dinoflagellata. 3, Glenodinium einctum, Ehrb., one of the Peridiniaceae ;
a, amyloid granules ; 6, eye-spot ; c, chromatophores ; d, flagellum of the transverse groove ;
«, flagellum of the vertical groove ; v, vacuole. 4, the same seen from the hinder pole. 5,
cuticle of Histioneis cymbalaria, iStein, from the Atlantic ; i, ventral process ; k, cuticular
collar ; I, posterior process. 6, the same seen from the dorsal surface ; m, cephalic funnel
(epitheca). 7, cuticle of Amphisolenin globifera, Stein, from the Atlantic, seen from the left
side ; m, epitheca ; o, the fundus from which the sulcus proceeds to the sub-terminal annulus ;
p, pharynx ; q, the shrunken protoplasm. 8, cuticle of Ornithocereus magnificus, Stein, from
the Atlantic ; m, m', the epitheca ; r, r', the two large ribs of the cuticular collar ; s, the two
rows of cuticular teeth. 9, cuticle of Ceratocorys horrida, Stein, from the Southern Ocean ;
p, p', borders of the annulus expanded into a rim ; w, x, y, plumose spines of the left margin
of the sulcus. (After Lankester and various authors.)
THE MAST1GOPHORA 185
B. Annulus spiral with a single pitch, sulcus slightly (Spirodinium)
or markedly (Pouchetia) spiral, decussating the annulus at both ends.
The transverse flagellum arises at the anterior end of the annular spire,
the longitudinal flagellum at the posterior end of the sulcar spire.
Spirodinium, Schutt ; Cochlodinium, Schutt ; Pouchetia, Schu'tt. All
marine.
Pouchetia resembles Cochlodiniunt, but is distinguished by the
possession of a complicated stigmatic apparatus consisting of a red or
black pigmented body with one or more large refractive lens-like
spherules adjoining it.
The interesting genus Polykrikos, Btitschli, consists of two, four, or
rarely eight individuals united together into a colonial organisation
(Kofoid [10a]). It is also peculiar in the possession of nettling organs,
and is said to present holozoic nutrition. Coasts of Europe and California.
All Gymnodiniaceae may be naked or enclosed temporarily in a
gelatinous membrane. The tribe includes marine and freshwater species.
TRIBE 2. PROROCENTRACEAE.
Carapace bivalve, perforated with numerous pores, without annular
plates and without annulus, the two halves meeting directly like the
edges of two opposed watch-glasses; longitudinal flagellum has the
•character of a tractellum with the transverse flagellum vibrating about
its base ; chromatophores yellow ; contractile vacuoles represented by
pusulae opening into the groove from which the flagella arise at the
^interior end of the cell-body.
At the time of division each daughter-cell receives one parent valve
and forms the other anew. The Prorocentraceae are entirely marine.
Lotsy (12) regards this tribe as being probably similar in some respects
to the ancestors of the Diatomaceae.
Exuviaella, Cienkowski, rounded in front and behind. Prorocentrum,
Ehrenberg, heart-shaped, flattened, pointed behind, with rostral prolonga-
tion of one of the valves at the anterior or flagellar end.
TRIBE 3. PERIDIXIACEAE.
These are characterised by the possession of a multitabulate cellulose
.carapace or cuirass, each valve being composed of at least two plates
which are frequently areolated, and, in addition, there are three or more
mmular and sulcar plates. The longitudinal flagellum plies in the
sulcus ; the transverse flagellum arises at the junction of sulcus and
annulus and vibrates in the latter groove (Fig. 12).
The cellulose membrane which constitutes the carapace or cell-wall
•of the Peridiniaceae is perforated by minute pores and is generally
provided with processes which may take the form of horns, spines, or
aliform expansions.
Multiplication takes place by oblique longitudinal (rarely transverse)
division, each daughter-cell receiving half of the parent carapace, that is
to say, half of each valve, and regenerating the other half. Resting
:sporocysts are enclosed in a gelatinous membrane, and it may be noted
1 86
THE MASTIGOPHORA
that the endogenous formation of swarm-spores results in the production
of gymnodiniform young.
Chromatophores, indefinite in number, may be green, reddish yellow,
or absent. The reddish-yellow variety of chlorophyll has been named
peridiniu (Schiitt). The colour of the chromatophores turns green at
death owing to the solubility of the peridinin. Many genera comprise
both coloured and colourless species, but the latter are furnished with
leucoplasts. Other plastids described as fat-forming bodies or lipoplasts-
are also met with.
The vacuole-system consists of saccules and pusules discharging into
the depression from which the Hagella arise.
The excrescences of the carapace serve as floats for these pelagic
organisms and occur as linear (Ceratium, Fig. 11) or foliaceous
FIG. 11.
Ceratium tripos. Dorsal view
shortly after fission, the two
daughter individuals still at-
tached to each other. «, the
anterior individual protected
by the greater part of the
parent's epitheca ; 6, the pos-
terior individual protected by
the greater part of the hypo-
theca. (After Sohiitt.)
FIG. 12.
Peridiniu m divergens. Ventral view
.showing the vacuole-system. c.p, the
small collector-pusule surrounded by :i
rosette of still smaller pusules which
open into it; s.p, the large sac-pusule or
reservoir ; both opening into the fundus
(/), from which both the transverse flagel-
lum (0 lying in the annulus (a) and the
longitudinal flagellum (/) arise. (After
Schiitt.)
(Ornithocercus, Fig. 10 (8)) expansions. At the anterior or apical end of
the cell there is an apical pore which is frequently closed by a perforated
plate resembling a madreporic plate (e.g. Blepharocysta}. The sulcus is
ventral, but there is no plane of symmetry.
Some species of Ceratium and Peridinium are found in freshwater
lakes, but the other genera appear to be exclusively marine.
In respect of individual numbers the principal habitat of the Peri-
diniaceae is in the cold waters of the North Sea, Baltic, and North
Atlantic. In point of specific divergence the southern waters are richer.
Individual variation is often excessive, and seasonal dimorphism has also
been noted.
Genera and species are determined by the form of the body and by
the characters of the cuirass.
The Peridiniaceae are divided into four families as follows : —
FAMILY 1. GLENODINIIDAE, intermediate between Gymnodiniaceae and
Peridiniaceae. Cuirass soft, membranous, consisting of two structureless-
THE MASTIGOPHORA 187
valves with an anmilus between them. Glenodinium pulvisculus, Ehrb.
(Fig. 10 (3 and 4)).
FAMILY 2. PTYCHODISCIDAE. Body lens -shaped, valves perforate,
annulus soft, membranous. Ftychodiscus nocticula, Stein.
FAMILY 3. CERATIIDAE. The typical genera are the well-known
forms of Ceratium and Peridinium. The valves of the cuirass are described
as the epitheca and the hypotheca respectively. The former carries the
apical pore and the latter the sulcus. But the sulcus sometimes extends
beyond its decussation with the annulus up the ventral side of the
epitheca to the apex of the cell, e.g. in Steiniella, Schiitt, and Gonyaulax,
Diesing ; or the sulcus may be short, extending equidistantly on either
side of the annulus as in Protoceratium, Bergh.
In the genus Ceratium we meet with two-, three-, four-, and five-
horned varieties. The chromatophores of the freshwater species of the
genus are green, of the marine species yellowish to brownish in colour.
Some Ceratiidae are spherical, as Blepharocysta, Ehrb., in which the
annulus and sulcus are only indicated by the arrangement of the plates.
Closely allied to Blepharocysta is the genus Podolampas, St., which has a
peridinioid form of body though a different tabulation. Others are
fusiform like the remarkable genus Oxytoxum, Stein. In Ceratocorys
horrida, Stein (Fig. 10 (9)), the borders of the annulus are expanded like
the rim of a hat, while the left sulcar margin is expanded into a wing
bearing long plumose spines. Pyrophacus is an oyster-shaped Ceratian
in which sporulation has been observed by Schiitt. The new genera
Hderodininin, Murrayella, Acanthodinium have recently been described by
Kofoid.
FAMILY 4. DIXOPHYSIDAE. The shell is divided by a sagittal suture
into two lateral subequal portions. The epitheca is flattened and much
smaller than the hypotlieca. The borders of the annulus are funnel-
shaped, and minute brown-coloured corpuscles called Phaeosomata often
occur in the space between the two superimposed funnels. The right
sulcar border is inconspicuous, but the left border may be monstrously
developed into wings and spines (e.g. Ornithocercus, Fig. 10 (8)).
In Amphisolenia (Fig. 10 (7)) the epitheca is excessively reduced, consist-
ing of two minute plates united together by a sagittal suture. The dis-
proportionately large hypotheca in this genus consists of two elongated
plates likewise united by a sagittal suture. The sulcus of Amphisolenia
(Fig. 10 (7)) proceeds from the subterminal annulus along the neck of the
cell for a distance equal to about one-quarter of the length of the body,
terminating at a rather deep pit, representing the depression from which
the flagella arise in other forms. This depression may be conveniently
distinguished by the term flagellar fundus or simply the fundus.1
In AmphisQlcnia the protoplasmic contents of the cuirass consist of
a nucleus, a moniliform chromatin reticulum, and several ellipsoidal
plasmosomes of amyloid character. A pusule situated near the nucleus
opens by a slender canal into the flagellar pore, and one or more accessory
pusules may lie near it in the cytoplasm.
1 The German term is "Geisselspalte." It is not a true pharyngeal pit although
it strongly resembles one.
1 88 THE MASTIGOPHORA
Other genera of Dinophysidae are Phalacroma, St. ; Dinophysis, Ehrb. ;
Histioneis, St. (Fig. 10 (5, 6)), Citharistes, St.; Triposolenia, Kofoid — San
Diego region of the Pacific.
SUB-CLASS V. CYSTOFLAGELLATA.
There are only three genera in this sub-class, and of these
Nodiluca has long been known as a widely distributed organism
that is often the principal cause of the phosphorescence of the
surface of the sea. The other two genera are little known.
Nodiluca possesses a sub-spherical body with bilateral symmetry,
the median plane of symmetry being determined by an elongated
groove on the ventral side called the peristome (Fig. 15 (5)), at the
bottom of which is the mouth. The nutrition is holozoic, and the
mouth leads directly into the central part of the protoplasm, from
whence trabeculae, exhibiting in life a streaming of the granules,
radiate outwards towards the periphery. In certain regions the
trabeculae are concentrated in the form of dense groups of fibrillae
giving rise to a fibrillar plexus. One such plexus arises from the
posterior end (/) of the central protoplasm, and is inserted along a
thickened linear area of the integument behind the peristome called
the bacillary organ, "Staborgan" (Fig. 15 (5, c)).
The integument consists of a resistent ectoplasm, a dense
reticulate layer of alveolar protoplasm. The striated proboscis-
like tentacle which arises in the middle line at the anterior end
of the peristome, and constitutes one of the most notable features
of its organisation, has a length equal to half the diameter of the
sphere. It is a flattened contractile organ, convex on its outer side
and concave on the inner adoral side. The protoplasmic trabeculae
which traverse the tentacle are so disposed as to produce a striated
structure comparable to that of striped muscle-fibres.
Other peristomial organs are the dentiform process ; the flagellum,
which is borne upon or near a protuberance termed the lip ; and
lastly the mouth. The tooth l and the lip are placed asymmetri-
cally upon the right wall of the peristome. The mouth occupies
the posterior two-thirds of the fundus of the peristome, which is
deepest behind and becomes progressively shallower in front. In
front of the mouth, that is to say, in the anterior third of the
peristome, are the lips, with the flagellum, the tooth, and the
tentacle. The flagellum lies well within the peristome and requires
practised observation for its discovery.2 It resembles the typical
flagellum of Mastigophora, namely, a filament of uniform thickness
from base to apex. The tentacle can be extruded far beyond the
confines of the peristome, but it can also be retracted, rolled up, and
so escape superficial observation.
'• The tooth is a protoplasmic organ. - It was discovered by Krohu in 1852.
THE MAST1GOPHORA
189
The nucleus is lodged within the central protoplasm, and
presents during life a transparent, homogeneous appearance.
The ingested food is enclosed in food-vacuoles, Avhich are some-
times so large as to occupy the greater portion of the body. No
contractile vacuole has been observed. The products of metabolism
consist of albuminoid and fatty granules.
Neither the slow contractions of the tentacle nor the rapid
vibrations of the cilium are sufficient to impart movements of pro-
gression to the inert body of Noctiluca, which merely drifts with the
rest of the plankton, kept afloat by its own buoyancy. The
FIG. 13.
Sporulation by blastogenesis in Noctiluca miliaris, Sur. A, surface view of the germinal
disc, showing the nuclei that give rise to the nuclei of the spores. Each nucleus (n) is accom-
panied by an archoplasmic body (a). B, cleavage-products (buds) in side view. C, L>, buds
in process of division. The archoplasmic body («) is seen to have divided before the nucleus
(/(). K and F, later stages of blastogenesis. (After Doflein.)
phosphorescence of Noctiluca is the manifestation of its response to-
mechanical, electrical, thermal, and chemical stimuli. According
to the observations of Quatrefages (quoted by Watase), " the light
emitted from the whole body, or any of its parts, is composed of a,
vast number of instantaneous scintillations."
The life-history of Noctiluca comprises the phenomena of simple
longitudinal fission (Fig. 15), resting-phase, conjugation, and blasto-
genesis. The transition of an ordinary individual into the resting
condition does not involve the formation of a protective cyst-
membrane, but simply the degeneration of the peristome and its
annexes.
When two individuals come together for the purpose of con-
i go THE MASTIGOPHORA
jugation, they attach themselves at the peristomial region and
gradually fuse together to form a zygote having twice the normal
volume. The fusion of the nuclei of the conjugants has been
observed directly, under the microscope, by Cienkowski and later
by Plate.
It seems likely, although still awaiting demonstration, that the
production of swarm- spores (zoospores) by exogenous budding
depends upon previous conjugation.
The production of buds is limited to a particular area of the
sphere, namely, the area corresponding with the peristomial region
where the central protoplasm is massed.
The cleavage of nucleus and protoplasm
proceeds in a manner analogous to the
discoidal cleavage of a yolk-laden egg
(Biitschli). .Nearly all the parent pro-
toplasm is used up in the formation of
FIG. 14. the buds, the full number of which
Two ripe spores of Noctttum amounts to 512.
mlliarls, showing n. nucleus; /', m, i ' <• i i •
flageiium ; 6, the body interpreted Ihe phenomena of karyokmesis in
to,be a blepharoblast or a centro- Nnriiliirn Tvrpsjpnl- cnmp inrprpstino-
some. (After Ishikawa.) present Testing
features. There is outside the nuclear
membrane, but in the neighbourhood of the nucleus, a relatively
large archoplasmic body. Before division of the nucleus occurs,
this body elongates to assume a dumb-bell shape (Fig. 3, A), Avith
an aster at each end. The chromatin of the nucleus concentrates
into a number of elongated moniliform chromosomes, and then the
nucleus warps itself round the central part of the archoplasmic
body, forming a spindle-like body round the achromatic spindle of
the archoplasmic body (Fig. 3, B). Finally, the chromosomes
divide into two parties, which travel to the opposite poles of the
spindle, and then both nucleus and archoplasm divide transversely.
The buds project from the surface of the body, but remain
attached to it until all have attained a certain size, and until each
has acquired its flagellum, which represents the cilium of the adult
.Nodiluca.
The detached free-swimming buds have a dinoflagellate appear-
ance, and it may be broadly stated that the blastogenesis of
Nodiluca, results in the formation of gymnodiniform young (Fig.
14). The growth of the young into the adult condition has not
been observed.
The sub-class contains only three genera: Nodiluca, Suriray, 0'3-1'25
mm., probably cosmopolitan; Leptodiscus, Hertwig, G'6-1'5 mm. ; and
Craspedotella, Kofoid (8), 0'15-0'18 mm. — E. Pacific. Craspedotella has
a strong resemblance to a craspedote medusa in form, being bell-shaped
and having a distinct velum at the margin.
THE MASTIGOPHORA
191
Fio. 15.
Nwtiluca miliaris, Suriray. 1, 2, two stages in the longitudinal lission ; n, nucleus ; N,
food - particles ; t, tentacle. 3, aboral view; a, entrance to the peristome ; c, the bacillary
organ ; d, the tentacle ; ft, the nucleus. 4, the animal acted upon by iodine solution, showing
the protoplasm like the "primordial utricle" of a vegetable cell shrunk away from the cuirass.
5, lateral view, showing (a) the entrance to the peristome in which 6 is placed ; <;, the bacillary
organ ; <?, the tentacle ; e, the mouth and pharynx, in which the flagellum is situated ; /, broad
plexus of tibrillae passing from the central protoplasm to the bacillary organs; h, nucleus.
After Lankester.)
SUB-CLASS VI. SILICOFLAGELLATA.
This division of the Mastigophora affords an apparent transition
from the Flagellata to the Radiolaria. It is monotypic, compris-
ing the single species Distephanus speculum, Stohr, which is para-
sitic upon or commensal with Radiolaria, and while possessing a
flagellum, has also a fenestrated siliceous skeleton.
LITERATURE.
Since the publication of Biitschli's treatise on the Mastigophora in Bronn's
Klassen und Ordnungen dcs Tfiicrreichs, Bd. i. Abth. 2, 1885, this class of
Protozoa has received the fullest general treatment in the pages of Engler and
192 THE MAST1GOPHORA
Fraud's Die naturlichen Pflanzenfamilien, where the Flagellata have been
written upon by G. Senn (Leipzig, 1900) ; the Peridiniales by F. Schiitt (1896) ;
and the Volvocaceae by N. Wille. Further references will be found in the
bibliography appended to the volume on the Protozoa by G. N. Calkins in the
Columbia University Biological Series (1901).
In the following list will be found references to some of the principal papers
mentioned in the text : —
1. Apstein, C. Pyrocystis lunula. Lab. inter. Meeresforsch. Kiel, viii., 1906,
p. 263.
2. Biackman, F. F., and Tansley, A. G. A Revision of the Classification of
the Green Algae. New Phytol. i., 1902.
3. Dobell, C. C. Structure and Life-History of Copromonas. Q. J. Micr. Sci.
lii., 1908, p. 75.
4. Goldschmidt, R. Lebensgeschichte der Mastigambben. Arch. Prot. Suppl.,
1907, p. 83.
5. Hartman, M., and von Prowazek, S. Blepharoblast, Caryosom und
Centrosom. Arch. Prot. x., 1907, p. 307.
6. Hickson, S. J. Reproduction and Life-History of the Protozoa. Trans,
Manch. Micr. Soc., 1900.
7. Keeble, F. W., and Gamble, F. W. The -Green Cells of Convoluta. Q. J.
Micr. Sci. li., 1907, p. 167.
8. Kofoid, C. A. Craspedotella. Bull. Mus. Harvard, xlvi. 9, 1905.
9. New Species of Dinoflagellates. Ibid. 1. 6, 1907.
10. Dinoflagellata of San Diego. Univ. California Pub. Zool. ii. 8,
1906 ; Hi. 6, 7, and 8, 1906 ; and Hi. 13, 1907.
10a. Polykrikos. Zool. Anz. xxxi., 1907, p. 291.
11. Lohmann, If. Die Coccolithophoridae. Arch. Prot. i., 1902, p. 89.
12. Lotsy, J. P. Vortrage liber botanische Stammesgeschichte. Jena, 1907.
13. Minchin, A. E. Investigations on the Development of Trypanosomes.
Q. J. Micr. Sci. Hi., 1908.
14. Moore, J. E. S. The Cytology of the Trypanosomes. Ann. Trop. Med. i.,
1907.
15. Murray, G., and Blackman, V. H. The Nature of the Coccospheres and
Rhabdospheres. Phil. Trans, vol. cxc., 1898, p. 427.
16. Prowazek, S. von. Flagellatenstudien. Arch. Prot. ii., 1903, p. 195.
17. Untersuchungen iiber einige parasitische Flagellaten. Arb. k.
Gesundheitsamte, xxi., 1904, p. 1.
18. Robertson, M. Pseudospora volvocis. Q. J. Micr. Sci. xlix., 1905, p. 213.
19. Schaudinn, F. Generations- und Wirtswechsel bei Trypanosoma. Arb. k.
Gesundheitsamte, xix., 1902, p. 169.
20. Untersuchungeu iiber die Fortpflanzung einiger Rhizopoden. Ibid.
1903, p. 547.
21. Wenyon, C. M. Observations on the Protozoa in the Intestines of Mice.
Arch. Prot. Suppl., 1907, p. 169.
22. West, G. S. A Treatise on the British Freshwater Algae. Cambridge,
1904.
23. Woronin. Chromophyton rosanqffii. Bot. Ztg., 1880.
24. Zederbauer, E. Geschlechtliche u. ungeschlechtliche Fortpflanzung von
Ceratiwn. Ber. d. D. bot. Gesell. xxii. 1, 1904.
THE PROTOZOA (continued)
SECTION G. — THE HAEMOFLAGELLATES AND ALLIED FORMS1
Order Lissoflagellata.2
Sub-Order MONADINA.
Family TRYPANOMORPHIDAE.
Genus Trypanomorpha.
Sub-Order HETEROMASTIGINA.
Family TRYPANOSOMATIDAE.
Genera Trypanophis, Trypanoplasma,
and Trypanosoma.
1. INTRODUCTORY.
THE Haemoflagellates, or Trypanosomes, although possessing in
common a uniform type of organisation, probably do not all belong
to a single, well-defined group of monophyletic origin. They are
preferably regarded as an assemblage of forms which have sprung
from two quite different stocks, the resemblances exhibited being
due to convergence, brought about by the acquirement of similar
adaptations in response to their similar and highly specialised mode
of life. They are entirely parasitic, their characteristic habitat
being the blood of a Vertebrate ; and, as is well known, certain of
them are the cause of severe, often fatal illness.
The Haemoflagellates possess either one or two flagella. When
there are two, they originate close together, at or near the anterior
end of the body. One is free and directed forwards ; the other
turns back and is attached for the greater part of its length to the
side of the body, by means of an undulating membrane, ultimately
terminating in a free portion directed posteriorly. Thus a Hetero-
mastigine condition is found. When only one flagellum is present
1 By H. M. Woodcock, D.Sc. (Loud.), Assistant to the University Professor of
Protozoology.
2 The classification of the Flagellates here made use of differs somewhat from that
adopted in the account of the Mastigophora. The position of the Trypanosomes
according to that scheme will be seen on reference to pp. 167, 168.
193 13
194
THE HARM OF LA CELL A TES
it is invariably attached in this manner, but the flagellum is
probably not homologous in all these cases. In certain Trypano-
somes which are to be derived from a Monadine ancestor, it is, of
course, the single flagellum that is represented, with the free part
directed anteriorly ; other forms, however, are rather to be looked
upon as derived from a Heteromastigine ancestor, the flagellum
that persists being the trailing, posteriorly directed one (the
so-called " Schleppgeissel").1 There are two nuclear bodies, one,
the trophonucleus, regulating the trophic life of the cell, the other,
the kinetonucleus, directing its locomotor activities.
FIG. 1.
" Undulina ranarum," Lankester, 1871. In 13 the nucleus is shown.
The most general method of reproduction is by binary, longi-
tudinal fission ; but multiple division or segmentation is also met
with. As regards the life-cycle of the parasites, only little is as
yet known in most cases. From the results of the most recent
researches, however, it certainly appears probable that, apart from
various blood - sucking Invertebrates which may (mechanically)
transmit a given parasite, there is, in general, a true alternate host
for each form ; one, that is, in which definite phases of the life-
cycle — including, most likely, sexual conjugation — are normally
undergone. Further knowledge on this subject is greatly needed.
Historical. — The first observation of a Trypanosome is probably
to be ascribed to Valentin, who, in 1841, announced his discovery
1 This flagellum is also termed the gubernaculum (see p. 159).
THE HAEMOFLACELLATES
'95
of Amoeba-\ike parasites in the blood of a trout. In the two or
three years following, Remak, Berg, and others recorded the
occurrence of Htiematozoa which were undoubtedly Trypanosomes
in different fishes. The parasite of frogs was first seen by Gluge
(1842), and in July 1843 Mayer described and figured certain
corkscrew-like and amoeboid organisms from the blood of the same
animal, which he termed variously Amoeba rotatoria and Paramoecium
costatmn or loricatum. A few months later (November) Gruby also
published (24) an account of this parasite, to which he gave the new
generic name of Trypanosoma. The same form was subsequently
described and figured by Lankester (30) in 1871, who, unaware of
Gruby 's work, called it Undulina ranarum ; this author was the
first to indicate the presence of a nucleus in the organism (Fig. 1, B).
The well-known parasite of rats was discovered by Lewis, in India, in
1878, and was afterwards named Herpetomonas lewisi by Kent.1 It
is to Mitrophanow (1883 to 1884) and Danilewsky (1885 to 1889),
however, that we owe the first serious attempts to study the com-
parative anatomy of these
Haematozoa. The work of
the latter researcher in par-
ticular is deserving of recog-
nition, especially when the
primitive state of knowledge
in regard to blood-technique
in those days is borne in
mind. Some of Danilewsky's
figures of a Trypanosome of
birds are reproduced in Fig. 2.
Trypanosomes were first
met with in cases of disease
by Griffith Evans, who, in
1880, found them in the blood
of horses suffering from Surra
in India. The organisms were
thought by him to be Spirilla.
Steel rediscovered the same
form a few years later and
took a similar view of its
affinities, naming it Spirochaeta
evansi. In 1894 Bruce found the celebrated South African parasite
( T. bnicii) in the blood of cattle and horses laid low with Nagana,
or Tsetse-fly disease ; and this worker subsequently demonstrated,
in a brilliant manner, the essential part played by the fly in trans-
mitting the parasite. Brace's discovery may be said to have
inaugurated a rapid increase in the number of known forms, the
1 This form is now placed in the genus Trypanosoma.
A-C, different forms of Trypanosoma, sangulnis
avium, Danilewsky. D, the same parasite dividing
longitudinally . n, nucleus ; u.m, undulating mem-
brane ; /, nagellum. (After Danilewsky.)
196 THE HAEMOFLAGELLATES
knowledge of which has in many cases thrown light upon the
etiology of maladies previously obscure. Thus, two characteristic
diseases, Dourine, which afflicts horses and mules in Northern
Africa and the Mediterranean littoral, and Mai de Caderas of
horses in South America, were next shown to be caused by
different Trypanosomes ; and since then many other varieties of
trypanosomosis have been described, chiefly from Africa, the home
of the dreaded Tsetse-fly.
Prominent among them, unfortunately, is human trypanosomosis.
The credit for first recognising a Trypanosome in human blood,
and describing it as such, must undoubtedly be assigned to Nepveu
(1898). The parasites were not definitely associated with disease,
however, till 1901, when they were seen in the blood of a European
in Senegambia suffering from intermittent fever. Forde first found
the organisms, but was uncertain of their nature ; he showed them
to Button, who recognised them as Trypanosomes, and gave this
form the name of Trypanosoma gambiense. A year later (1902)
Castellani discovered what has been shown to be the same parasite in
the cerebro-spinal fluid of patients suffering from sleeping-sickness
in Uganda, and it has since been conclusively proved by Bruce
and Nabarro that this organism is the true cause of that terrible
disease.
More important, however, from the standpoint of Protozoology,
than these interesting medical discoveries have been the investigations
by Brumpt, Laveran and Mesnil, Le"ger, Minchin, Schaudinn, the
Sergents, and others during the last few years upon numerous other,
mostly " tolerated " forms ; to their researches, indeed, we owe most
of our knowledge at the present time, relating to the life-cycle of
the Haemoflagellates. And it is fitting, here, to pay a tribute to
the value of the characteristic stain first made known by Roman-
owsky, and its subsequent modifications (e.g. those of Giemsa,
Laveran, Leishman, etc.), without which, it is safe to say, thi»
progress would have been impossible.
2. OCCURRENCE AND TRANSMISSION ; HABITAT AND EFFECTS
ON HOST.
(a) Occurrence and Transmission.
Trypanosomes are harboured by members of all the chief classes
of Vertebrates, with the exception of Cyclostomes. Mammals, birds,
and fishes furnish, however, by far the greater number of hosts. Fewer
parasites have been described from Amphibia, and up till now only
from frogs ; while, among Reptiles, their occurrence has only been
observed in two or three instances. Data with regard to the
frequency with which individual species are to be met with, in any
THE HAEMOFLAGELLATES 197
particular kind of host, are as yet somewhat scanty. In one or
two cases, however, the parasites are known to be fairly common.
Trypanosoina lewisi, for example, occurs in a considerable percentage
of sewer -rats throughout the world, having accompanied these
rodents in their ubiquitous migrations ; the proportion of hosts
infected varies usually from 10 to 40 per cent.
In considering the occurrence of Trypanosomes in Mammals
careful distinction must be drawn between true or natural hosts
and strange or casual ones. In the former case, by reason of the
long-existing association between host and parasite, a condition of
mutual toleration has been reached, which, in ordinary circum-
stances, enables a proper balance to be maintained on both sides.
On the other hand, when a Trypanosome gains an entry into
animals Avhich have never been previously liable, by their dis-
tribution, to its invasion, and which are consequently unaccustomed
and unadapted to the organism, it usually produces markedly
harmful effects. Such a state of affairs has resulted, for example,
from the march of civilisation into the " hinterlands " of the
various Colonies, where man, together with the numerous domestic
animals which accompany him, has been brought into proximity to
big game, etc., and what is equally important, into the zone of the
blood-sucking insects which prey upon the same.
Very many of the common domestic Mammals can be success-
fully infected (either in an accidental way or else artificially) with
different " pathogenic " Trypanosomes, to which they succumb
more or less readily ; they cannot be regarded, however, as natural
hosts of those Trypanosomes. In considering disease-causing forms,
the more narrowly the original source of the parasite concerned is
defined, the closer do we get to the true Vertebrate host or hosts.
In the case of the Nagana parasite, it has been shown that such are
almost certainly to be found among buffaloes and various Antilo-
pidae (e.g. the gnu, "koodoo," etc.), while, again, the native host of
T. equinum, of Mai de Caderas in South America, is most probably
the capybara. It may be said undoubtedly, with regard to the
many lethal Trypanosomes now known, that there is, in each case,
some indigenous wild animal tolerant of that particular form,
which serves as a latent source of supply to strange Mammals
coming into the vicinity.
Transmission. — In the transmission of the parasites from one
Vertebrate individual to another, a blood-sucking Invertebrate is
almost invariably concerned.1 In the case of all Trypanosomes of
1 Trypanosoina equiperdum, the cause of Dourine or horse-syphilis, is conveyed by
the act of coitus ; and it is quite uncertain whether this parasite is ever transmitted
naturally by an insect. Moreover, Koch has recently brought forward evidence
(29, Schluss - Bericht) which, he thinks, tends to show that the human parasite
(T. gambiense) can also lie transmitted by sexual intercourse.
1 98 THE HAEMOFLAGELLATES
warm-blooded Vertebrates for which the transmitting agent is
known, this is an insect, generally a member of the Diptera ; in
that of Trypanosomes of cold-blooded Vertebrates the same role is
usually played by an Ichthyobdellid leech (Piscine forms), but
possibly now and again by an Ixodes (some Amphibian or Eeptilian
forms).
The actual relation between the parasite and the transmitting
Invertebrate has long been questioned, and there are still some
very important instances in which the real state of affairs is not
certain. But it would seem, from the. results of recent work,
that in most cases some Invertebrate or other acts as a true
alternate host. Thus, so far as leeches are concerned in connec-
tion with the Trypanosomes of fishes, the investigations of Leger
(50), Brumpt (10-12), and Keysselitz (27) have made it clear that
the parasites not only live quite normally, but undergo a definite
evolution in particular organs of leeches which have fed on infected
fish. Frequently this further development can only proceed, at
least to its full extent, in a certain leech to the exclusion of others
(e.g. in a Hemiclepsis and not in a Piscicola, or vice versa) ; this restric-
tion points distinctly to the leech in question being a specific natural
host. Again, according to the celebrated researches of Schaudinn
(75) on an Avian Trypanosome, Trypanomarpka (Trypanosoma)
noctuae, a species of gnat (Culex) provides the alternate host,
in which a complex part of the life -cycle takes place. It is
interesting to note that, as might be expected, there is a regular
periodicity in the infectivity of the gnat ; that is, it can only
transmit the infection after such and such an interval has elapsed
since the meal when it became itself infected. Coming, lastly, to
the Mammalian forms, Prowazek (68) has described phases of
development of T. lewisi in the rat-louse (Haematopinus sp.),
and considers that this insect serves as a true Invertebrate host ;
though he was not able to prove the actual transmission of the
parasites back to the rat by means of it.1
Interest and discussion has mostly centred, however, upon the
part played by the transmitters of the lethal Trypanosomes, and
it is only quite recently that any light can be said to have been
thrown upon the subject.
It has for some time been generally recognised that, in many cases at
any rate, a particular biting-fly is chiefly responsible for the spread of a
particular parasite in an infective district. In such cases, a striking
coincidence usually exists between the area over which a certain trypanoso-
mosis is prevalent and the zone of distribution of a certain fly. Thus, of
two well-known African Trypanosomes, one, T. briicii, the cause of Nagana
1 This has been effected, however, by earlier observers (Rabinowitsch and
Kempner) by means of fleas, which are possibly the " right " insects.
THE HAEMOFLAGELLATES
199
or Tsetse-fly disease in South-East Africa, is conveyed by Glossina morsitans l
(Fig. 3, A and B), while the other, T. gambieiise, the cause of sleeping-
sickness, has for its carrier in Uganda another Tsetse-fly, G. palpalis.
Working upon this knowledge, many investigators have at one time
or another performed series of experiments with a view to finding out
whether any developmental cycle is undergone by the parasites while in
the fly, and whether definite periods of infectivity occur, on the analogy
of the malarial parasites in mosquitoes. The earlier results obtained
seemed to indicate that the role of the fly was purely mechanical — the
insect acting merely like an artificial inoculating tube. Bruce, in the
course of his pioneer work in Zululand, found that the flies could, with
D.
Various blood-sui-king flics. A and B, Glossina morsitans (transmits Trypanosmna brurii,
of Nagana), x 2 ; C, Hipi>(H>oscu rufipes (thought to transmit T. thdleri, the cause of " bile-sick-
iii-ss"), x U; I), Tn.lH.inns Uneola (probably conveys the Surra parasite, T. evansi), x 1J ; E,
Mnitin.Ti/.- -i-ii], -itfi'na (suspected in connection with T. equinvm, of Mai de Caderas), x 2J. (A and
B from Lav. and Mesn., after Bruce ; C after L. and M. ; D and B after Salmon and Stiles.)
varying success, infect a healthy animal if allowed to bite it up to forty-
eight hours after being themselves fed on an infected one, but not after-
wards. Similarly, Bruce, Nabarro, and Greig (8) ascertained that G.
palpalis could give rise to an infection ei«ht, twenty-four, or forty-eight
hours after feeding, but after two days they could no longer obtain a
successful inoculation. Moreover, some experiments extended over two
months gave no sign of any periodicity of infection. Nevertheless, these
workers found that the Trypanosomes could at all events live and retain
their mobility in the stomach of the fly up to seventy-one hours.
Similar results were obtained by Minchin, Gray, and Tulloch. In
their interesting report (59) these authors state that they could find
no evidence of a fly becoming infectious at any particular period after
1 Tliis parasite is also conveyed, in different districts, by G. pallidipe!! and
G.fnsca.
200 THE HAEMOFLAGELLATES
being fed, experiments being carried out up to an interval of twenty-two
days. An additional and significant fact remarked upon by them is that
only the first animal which the experimental fly was allowed to stab
became infected ; if the insect was removed before its meal was completed
and immediately placed on another animal, this latter did not become
infected. That is to say, after a fly had been allowed to, as it were, clean
its proboscis from the Trypanosomes remaining in it since its previous
meal (on an infected animal), it was no longer infectious.
These facts make it certain that Trypanosomes can be and are
conveyed by Tsetse-flies in a purely direct and mechanical manner ;
and so far as T. gambiense and sleeping-sickness in Uganda are
concerned, it is probable that their spread, through the agency of
G. palpalis, has been largely if not entirely in this way. But this
does not by any means end the matter.
Minchin, Gray, and Tulloch bring forward observations which
point to a commencing cycle of development of T. gambiense 1 in the
fly. Up to forty-eight hours the Trypanosomes present in the
stomach of an infected fly are markedly differentiated into two
types, which probably represent sexual forms. After forty-eight
hours a type of more indifferent character makes its appearance,
which usually becomes scanty with lapse of time, till at ninety-six
hours scarcely a Trypanosome can be found. It is interesting to
note that during this interval the parasites steadily increase in
size. Coming next to Koch's recent investigations on behalf of
the German Sleeping- Sickness Commission, a very important
observation is recorded (29). A species of Glossina, distinct from
G. palpalis, namely, G. fusca, was bred in captivity ; the individuals
born and reared under these conditions were regarded as certainly
free from Trypanosomes.2 Several of these flies were fed on rats
infected with T. gambiense. They were examined from ten to
twelve days later, and after this long interval were found to be
infected with those parasites. Moreover, individuals of another
Tsetse-fly, G. tachinoides, similarly fed, were also found to contain
T. gambiense after the same lengthy interval.
Still more recently Stuhlmann (80), in his description of G.
fusca, has published some extremely interesting notes on the relation
of T. bnicii to this fly. Using reared flies, considered to be certainly
free from infection, Stuhlmann was able to infect about 80 to 90
1 The case of T. gambiense in Glossina palpalis is unfortunately complicated by
the occurrence in the same species of fly of other Trypanosomes, distinguished by
Novy(61) as " fly-Trypanosomes. " One of these, T. grayi, at any rate is entirely
ditferent from T. ganibiense ; and it is highly probable that some of the observers (e.g.
Gray and Tulloch [23], Koch [28]), who first described what they regarded as
developmental phases of T. gambiense, were dealing in reality with T. grayi.
2 This is on the assumption, of course, that the parasites were not inherited ; but
most authorities seem to be agreed that hereditary transmission of Trypanosomes by
Tsetse-flies does not take place.
THE HAEMOFLAGELLATES 201
per cent, and in from two to four days was able to observe various
developmental phases of the parasites. This further development
continued on the flies being fed upon healthy animals, but only in
about 10 per cent of the individuals ; in the rest it gradually dis-
appeared. This percentage, it is instructive to observe, was about
the same as that of the Tsetses (G. fusca) found to be infected with
T. brucii (in all probability) in nature.
It will be seen that it is impossible to draw any certain con-
clusions from the present position of the problem. Nevertheless,
there is good reason to suppose that, for a given lethal Trypano-
some, there is a particular insect which is a true alternate host.1
It seems very probable that here, as among leeches, there are
right and wrong hosts for the parasites ; that while the com-
plete normal development, culminating in the transfer back to the
Vertebrate, can only take place in a certain species of fly, attempts
at development which are, to a varying degree, partially successful
may go on in other biting- flies ; these latter, however, being
able to act in relation to the Vertebrate host only as mechanical
.carriers.
Before leaving this question of the mode of transmission of
Trypanosomes, it is to be noted that Minchin has put forward (57)
an entirely new view with regard to the method of infection. His
idea is based especially upon the highly interesting discovery made
by him of the occurrence of cysts, doubtless for external dissemina-
tion by way of the anus, in one of the " fly - Trypanosomes,"
Trypanosoma grayi. Minchin suggests that there may be two
varieties of cyclical infection among the Haemoflagellates ; in the
.one, the parasite undergoes cyst-formation in the insect, resulting
in a contaminative infection of the Vertebrate, by means of its food
or drink ; in the other, distinguished as the inoculative type, the
infection takes place through the proboscis of the fly (as, for
example, in the malarial parasites). Up to the present, however,
T. grayi remains the only known form in the case of which infection
is most probably of the first type.2 From what has been learnt so
far of the development of other Trypanosomes — Avhether in leeches
or in insects — the distribution of the parasites in the body (see
under " Habitat") points at any rate to inoculative infection of the
Vertebrate. The possibility of the occurrence of both modes in any
.one Trypanosome is not, so far as is known, excluded ; but there
is, as yet, no definite evidence in favour of this.
1 For further remarks bearing on this point, see pp. 230-231, 261.
2 Although the Vertebrate host of T. grnyi has not been actually demonstrated,
both Minchin and others have made an important observation in connection with the
biology of the Tsetse-tty, which — taken in conjunction with the non-occurrence of
hereditary infection— seems to show that it is impossible for the parasites to be
merely fly-Trypanosomes. This is to the effect that the Tsetses, unlike mosquitoes,
/eed only on blood, never on foul or decaying matter of any kind.
THE HAEMOFLAGELLATES
(b) Habitat and Effects on Ho.<f.
1. Relation to the Invertebrate Host. — Schaudinn, in his work on
the parasites of an owl (Athene noctua) (I.e.), has described in full
the distribution and course of development of Trypanosomes in the
body of a gnat (Culex pipiens). Although, as is pointed out below
(see under "Life-Cycle"), it is now disputed how far Schaudinn's
description actually relates to Avian Trypanosomes, the great
interest excited by this author's work renders a brief abstract of
his account necessary.
prov.
oes.
Fie. 4.
Diagrammatical longitudinal section through Culex pipiens to show the distribution of thff
parasites. The arrows indicate the direction of their movement, the cTusters of stars the place*
of agglomeration, u.l, upper lip ; LI, lower lip; tip, hypopharynx ; ph, pharynx; s.g, salivary
gland ; ocs, oesophagus ; o.d, oesophageal diverticula (gas reservoirs) ; prov, proventriculus ;
st, stomach ; m.t, Malpighian tubes ; c, junction of ileum and colon ; aort, aorta. (After
Schaudinn.)
The distribution of the parasites 1 is intimately connected with the
process of digestion. Towards the end of the digestion of the imbibed
blood, the Trypanosomes, after a period of multiplication, enter upon ;v
resting phase, and are found either attached to or between the epithelial
cells. After a second meal another multiplicative period occurs, and the
parasites gradually collect in the anterior part of the stomach, where the
nutriment remains longest unabsorbed. Here (Fig. 4, prov) the organisms
begin to cluster in large numbers, being able to penetrate the delicate
surface of the layer of invaginated oesophageal epithelium in this region.
Finally, there is an enormous accumulation of the Trypanosomes at this
place, all arranged in rows and in a resting condition. The next inflow
1 Tliis summary relates to the first of the two parasites described by Schauiliim,
Trypanomorptia (Trypanosoma} noctnae.
THE HAEMOFLAGELLATES 203
of blood drives this mass before it, in the form of a rolled-up ball, until
it reaches the junction of the ileum and colon (Fig. 4, c), the narrowest
point of the intestine. The wall here is very thin and easily ruptured,
and most of the Trypanosomes pass through it, into the vascular lacunae
around, whence they are carried to the heart. Finally, the parasites
become arrested in the sinus surrounding the pumping-organ of the
pharynx, where they continue to multiply and collect again into
agglomerated masses, which press on the wall of the pharynx in this
region. By the end of the third digestive period, these clumps of
Trypanosomes have broken through, and partly block up the lumen ;
and in the next biting act they are forcibly ejected into the blood of the
owl. Thus the parasites cannot leave the gnat until the fourth meal,
including that which effected their entry, has taken place ; and Schaudinn
found that the shortest time elapsing between entrance and exit was seven
or eight days, when the insects were maintained at the optimum tempera-
ture for digestion.
An interesting discovery is the occurrence of true hereditary infection.
After breaking through the wall of the colon, a few of the Trypanosomes,
usually females, instead of being carried forwards, may pass to the
ovarian follicles, penetrate into the young eggs, and so infect a succeeding
generation.
According to Prowazek (I.e.), the behaviour of Trypanosoma
hwisi in Haematopmus and its passage through the louse resembles
in the main the account above summarised. Such differences as
there are stand in close relation, on the one hand, to the somewhat
different mode of feeding and of absorption of nutriment in the
louse, and on the other hand to the fact that T. hwisi appears to
be more resistant to " external " influences.
With regard to other Mammalian Trypanosomes, the evidence
so far available is mostly to the effect that they are confined entirely
to the alimentary canal, and never occur in other organs of the
insect. Concerning T. gambiense in G. palpalis, Minchin, Gray,
and Tulloch (I.e.) remark that these parasites were found only in
the mid-gut, and never passed either backwards into the proctodaeum
or forwards into the proventriculus.1 According to Stuhlmann (I.e.),
T. brucii is apparently much more at home in G. fusca (which may
prove to be its true specific host), being met with in different forms
from the hind-gut (colon) to the proboscis. But this author also
emphasises the fact that the Trypanosomes were never observed
anywhere else, and, particularly, never in the salivary glands. The
only positive observation of the occurrence of Trypanosomes in the
salivary glands which need be taken into account is the recent
statement made by Koch (29) that, of the different types which
1 Gray and Tulloch (/.c.) stated that they had observed T. gambiense in the
salivary glands, but Minchin has since shown that what they took to be salivary
glands was in reality proventriculns ; moreover, they may have been dealing, not with
T. gambiense, but with one of the other parasites in this fly.
204 THE HA E MO FLAGELLATES
he noticed in Glossinae (sp. not given), one which from its entire
agreement with T. gambiense was to be identified with that form
occurred in two instances in the salivary glands. If this observation
be corroborated, its importance is, of course, very great.
Several important facts have been lately brought forward by
Brumpt (10-12), which tend to show that the habitat of Piscine
Trypanosomes in leeches is also restricted to the alimentary canal.1
Three types of behaviour can be distinguished, (a) The parasites
develop solely in the stomach and never pass into the intestine or
into the sheath of the proboscis. At the moment when the leech
sucks the blood of another fish, the Trypanosomes pass into the
latter directly, by way of the proboscis. This mode is exemplified
by T. remaki of the pike. (/>) The development begins in the
stomach and is continued in the intestine, where the parasites may
remain for a long while. From the intestine the Trypanosomes
pass back into the stomach, to gain at length the proboscis-sheath.
T. granulosum of the eel is an example of this type. In the third
variety (c) the development goes on in the stomach, but the para-
sites succeed in passing finally into the proboscis -sheath; ex.:
T. danilewskyi of the carp. In the case of certain marine forms
(T. raiae and T. scyllii), whose development goes on in Pontobdella,
Brumpt found the parasites in the stomach and intestine, but could
not ascertain how they got back into the fish. Miss Robertson,
however, has lately described (72) various developmental phases
of a Trypanosome which she regards as identical with T. raiae, and
states that small slender forms do migrate up into the proboscis :
it is probably these which serve to infect the Vertebrate.
2. Relation to tlie Vertebrate Host. — Once an entrance into the
blood is effected, the parasites pass rapidly into the general circula-
tion, and are thus carried to all parts of the body. In considering the
distribution and numerical abundance or otherwise of the Trypano-
somes in any given individual, it is necessary to bear in mind
whether they are in a tolerant host or in an unaccustomed one.
Dealing with the former case first, the trend of observation points
to their being usually rather scarce, sometimes very rare. The
reason for this scarcity is probably the fact that multiplicative
phases are very rarely met with, at all events in the general
circulation. Except for a short period at the beginning of the
infection, multiplication appears to be largely in abeyance ; this has
been well shown by Laveran and Mesnil (37) in the case of T.
lewisi of the rat. The parasites are often more numerous in the
spleen, bone-marrow, kidneys, and liver than elsewhere ; and it has
been found that multiplication goes on rather more actively in the
capillaries of these organs. One very important point may be
1 Brumpt has recently noted (14), however, cases of hereditary infection of leeches,
with both Trypanosoma and Trypanoplasma.
THE HAEMOFLAGELLATES
205
conveniently mentioned here, namely, that hereditary infection of the
Vertebrate host is not known to occur in the case of most of
the great classes. Moreover, in Mammals, whether tolerant or
unaccustomed hosts, the parasites appear to be, as a general rule,
unable to traverse the (uninjured) placenta. Pricolo has recently
stated, however (67), that he has found T. duttoni in the foetus
of an infected mouse, and thinks this a case of true hereditary
infection.
The Trypanosomes in the active, motile form are always free in
the blood-plasma (intercorpuscular). It is very uncertain whether
the parasites ever come into relation with the blood -corpuscles.
According to Schaudinn's investigation on two Avian forms, one,
namely, Trypanomorpha(Trypanosoina}noduae, becomes in certain phases
attached to a red blood-corpuscle (ectocorpuscular), while at other
times it penetrates inside the corpuscle (endocorpuscular) and eventu-
ally destroys it. • The other form, Trypanosoma (Spirochaeta} ziemanni,
apparently draws up into itself the white corpuscle (leucocyte) to-
which it becomes attached. It must be admitted, however, that
some doubt exists as to these alleged occurrences.1 In addition
there are two or three very positive statements of observations
showing that other Trypanosomes, including Mammalian forms,
may come into relation with the red corpuscles ; see BufFard and
Schneider (16) with regard to T. equiperdum, and Voges (85) with
regard to T. equinum. On the other hand, Prowazek (68) could
find neither an ecto- nor an endocorpuscular condition in T. lemsi,
and considers that the habitat of this parasite is restricted to
the plasma.
Considering now the Trypano-
somes in an unaccustomed Mam-
malian host, for which they are
lethal, the parasites may either
remain infrequent or rare — some-
times, indeed, being unnoticed until
shortly before death — or they may
soon become numerous and go on
increasing (Fig. 5). In the latter
case the disease is acute and rapidly
fatal ; in the former it is more chronic
and lasts much longer, often several gjg^ °«! Wit* ; b,
months.
There is often considerable varia-
bility with regard to the appearance and number of the parasites in
1 It is said that Schaudinu has mistaken two distinct Haemosporidian parasites,
a Hcdteridium and a Leucocytozoon, for resting-phases of these otber Haematozoa (see
under " Life-Cycle ").
FIG. 5.
Trypanosoma i'/n/y>r/v/ii;/) (of Dourine),
eight days after
ites ; b, blood-
corpuscles. (After Doflein.)
206 THE HAEMOFLAGELLATES
the blood at any moment. Occasionally and at irregular intervals,
evidently following upon a period of multiplication, the Trypano-
somes may be fairly numerous, their appearance frequently coinciding
with an access of fever. At other times, they seem to vanish almost
entirely from the peripheral circulation ; for what reason, however,
is not certain. Some authorities attribute it to the rise in tempera-
ture, as being unfavourable to the parasites ; others think it is
due to the more potent operation of chemical and physiological
defensive agencies of the host at a higher temperature. However
this may be, it has long been known that certain of the organisms
situated, probably, in some internal, more favourable part of the
body can survive and give rise later to a fresh succession of
parasites in the blood.1
The main features of the illness show a general agreement,
whichever variety of trypanosomosis is considered; one symptom
may be, of course, more marked than another in a particular type.
The pathogenic effects are chiefly referable to disorganisation either
of the circulatory or of the nervous system, or of both combined.
Fever always occurs, at some time or other, during the course of the
malady. Its manifestation is extremely irregular, both in character and
in time of occurrence, and it is, therefore, usually readily distinguishable
from malarial fever. There is, particularly in chronic cases, marked and
progressive anaemia and emaciation, leading to pronounced enfeeblement,
which is, in fact, the most characteristic symptom of naturally occurring
trypanosomosis. A common feature is the occurrence of oedematous
swellings in various parts, chiefly in the neighbourhood of the genitals,
of the abdomen, and around the eyes. The parasites are often more
numerous in the bloody serosities bordering these places than in the
general circulation. This fact is of great importance in connection with
the transmission of Dourine. In this disease the parasites are rare in
the blood, but generally numerous in the immediate neighbourhood of
the oedematous excoriations on the penis, so that, in coitus, they come
into contact with the vaginal mucous membrane of a healthy mare,
through which they are able to pass.
Nervous symptoms may be only slightly noticeable (e.g. a dull and
lethargic tendency towards the close of the illness), or they may be
strongly in evidence, especially in Dourine, Mai de Caderas, and sleeping-
sickness. In the two former, more or less general paralysis of the
posterior part of the body frequently sets in ; Mai de Caderas of horses
in South America is, indeed, often called " hip-paraplegia." In sleeping-
sickness the Trypanosomes penetrate into the cerebro-spinal canal, and
.can usually be found upon centrifugalising a sufficient quantity of the
1 Holmes (Journ. Goinp. Pathol. xvii., 1904) and, more recently, Salvin-Moore and
Breiiil (Ann. Trap. Med. i., 1907) consider that these resistant forms, for which the
latter propose the term "latent bodies," are represented by certain of the amoeboid
involution-forms described by Bradford and Plimmer, Laveran and Mesnil, and
others (cf. p. 222).
THE HAEMOFLAGELLATES
207
fluid; they have also been seen, in post-mortem examination, in the
lateral ventricles of the brain. It is this invasion by the parasites of
the nervous system that marks the transition of the case from one of
" Trypanosoma-faveT " (while the parasites are confined to the blood) to
one of sleeping-sickness. The results of the change are soon apparent
in the onset of lassitude, tremor, and the other associated nervous
symptoms which characterise this dreadful malady.
Death from trypanosomosis is due either to weakness and emaciation
(in chronic cases), or to blocking of the cerebral capillaries by the parasites
(where these are abundant and the disease consequently acute and rapid),
or to the disorganisation of the nervous system (paraplegic and sleeping-
sickness forms). Laveran and Mesnil have expressed the opinion that
some factor in addition to the presence of the parasites themselves —
especially when these are rare — is requisite to explain the severe effects
produced, and suggest that the Trypanosomes secrete a toxine. Neither
they nor other investigators have, so far, been able to discover traces of
any such substance. In post-mortem examination, the most obvious
pathological feature is hypertrophy of the spleen, which may be very
pronounced. The lymphatic glands in the neck, inguinal region, etc.,
are often greatly swollen and contain numerous parasites.
The spleen and lymphatic glands are undoubtedly the organs
which react most strongly
to the parasites, and their
enlarged condition is, prob-
ably, to a great extent
due to enhanced activity
in elaborating blood -cor-
puscles and leucocytes to
cope with the enemy. In-
gestion and dissolution of
the Trypanosomes by
phagocytes has frequently
been observed (Fig. 6).
It is very likely also that
the haematopoetic organs
eecrete some chemical or
physiological substance
which exerts a harmful
action on the parasites,
causing them to undergo
involution and assume
weird-looking "amoeboid" and "plasmodial" forms.
In A the leucocyte is
Fie. 6.
Phagocytosis of T. lewisi.
beginning to engulf the Trypanosome ; in B the latter
is completely intracellular ; C-E show the gradual dis-
solution of the parasite (p). n, nucleus of leucocyte ;
c, ingested blood - corpuscles ; v, vacuoles remaining
after their dissolution. (After Lav. and Mesn.)
3. COMPARATIVE MORPHOLOGY.
Trypanosomes vary greatly with regard to size ; even in one
and the same species this variation is often noticeable, especially
208
THE HAEMOELAGELLATES
under different conditions of life. The well-known Trypanosoma
rotatorium of frogs (Fig. 8, A and B) is, taking it all in all, one of the
largest forms so far described. Its length1 varies from 40 to 60 //,
while its greatest width dorso-ventrally - is from 8 to 30 ^ ; in the
/*.-
H.
FIG. 7.
Representative Mammalian, Avian, and Reptilian Trypanosomes. A, Trypanosoma lewisi,
after Bradf. and Plim. ; B, T. brucii, after Lav. and Mesn., x 2000 ; C, T. gambiense (blood, T.-
fever), after Bruce and Nabarro ; D, T. equinum, after L. and M., x 2000; B, Trt/panomorpha
(Trypanosoma) noctuae, after Schaud. ; F, Trypanosoma avium, after L. and M. ; G, T. hannae,
after Hanna; H, T. (Spirochaeta) ziemanni, after Schaud. ; J, T. damoniae, after L. and M.,
x 2000. c.g, chromatoid grains ; v, vacuole ; l.s, longitudinal striation.
very wide individuals breadth is gained more or less at the expense
of length. Conversely, the human parasite, T. gambiense (Fig. 7, c),
is one of the smallest forms, its average size being about 21
to 23 ju, by 1 1 to 2 p.. The majority of Mammalian Trypanosomes
1 The length is always inclusive of the flagellum, unless otherwise stated.
2 Adopting Leger's convention, by which the convex side, bearing the undulating
membrane, is distinguished as dorsal ; the measurements of width always include the
undulating membrane.
THE HAEMOFLAGELLATES 209
are fairly uniform in size (Fig. 7, A-D), the chief exceptions being
T. theileri (Fig. 33), which is much larger than the rest, varying
from 30 to 65 p in length ; and T. nanum, which is correspondingly
minute, being only about 14 /A long. The Piscine forms, on the
other hand, though possessing an equally great range, exhibit a
more regular gradation. Starting with relatively small types, like
T. remaki, var. parva, with a medium length of 30 /x, parasites of all
sizes are to be met with up to T. granulosum (Fig. 8, K) and T. raiae
(Fig. 38, B), which are among the longest Trypanosomes known,
attaining a length of 80 //.
There is equally great diversity of appearance. Typically the
body is elongated and spindle-shaped ; it is generally more or less
curved or falciform, and tends to be slightly compressed laterally.
It may be, however, anything from extremely slender or vermiform
(Figs. 8, K; 34) to thick-set and stumpy (Figs. 8, A; 35). More-
over, apart from the fact that a full-grown adult, ready to divide,
is in many cases much broader than a young adult (cf. T. lewisi,
Fig. 20, B), considerable polymorphism also sometimes occurs (e.g.
T. rotatorium, Figs. 8, A, B; 37). Again, there can be little or no
doubt that, in some instances at any rate, sexual differentiation is
expressed by more or less pronounced differences in appearance.
In fact, from one reason and another, it is often practically impos-
sible to define any one type within hard and fast limits, either of
shape or size.
In the biflagellate, Heteromastigine forms (Trypanoplasma and
Trypanophis), the anterior extremity of the body is that, of course,
from which spring the two flagella. With regard, however, to the
correct orientation in the uniflagellate Trypanosomes (the genus
Tri/panosoma sens, lat.) considerable uncertainty exists. For the
present,1 in order to avoid confusion, the two ends may be desig-
nated as flagellate or flagellar, and non-flagellate or aflagellar
respectively. On the whole, the flagellar extremity is fairly
uniform and nearly always more or less tapering; but the non-
flagellate end presents great variation, being, as Laveran and
Mesnil point out, particularly plastic. On the one hand, it may
be blunt and even rounded off at the tip, as in certain individuals
of T. brucii (Fig. 7, B), T. equiperdum (Fig. 32, D), and in a Trypano-
some of Senegambian birds (Fig. 35) ; on the other hand, it may
be very long and attenuated, as in T. Jiannae (Fig. 7, G), occasionally
simulating a true flagellum to a remarkable degree, this being the
case in T. polyplectri. Between these two extremes all manner of
intermediate conditions are to be found. An instance which well
illustrates the great variability in one and the same form is seen in
1 The whole question is so closely bound up with that of the phylogeny of the
group that its consideration is best deferred until the two can be discussed together
(see below, p. 246).
210
THE HAEMOFLAGELLATES
Fio. 8.
Representative Amphibian and Piscine Trypanosomes. A and B, Trypanosoma rotatorium,
after Lav. and Mesn., x 1400; C, T. inopinatum, after Sergent, x 1000; D, T. karyozeukton,
after L. and M., x 2000. h, clear zone or halo around kinetonucleus ; eh, chain of chromatic
rodlets running between the two nuclei ; a.fl, anterior flagellum ; p.fl, posterior flagellum ; l.s,
longitudinal striations or myonemes ; v, cytoplasmic vacuole.
T. lewisi. Usually this parasite has a shai-p, pointed aflagellar end
(Fig. 7, A) ; but in many of the individuals found in rats which
211
have been recently infected (e.g. five or six days previously) this
extremity is enormously drawn out and tapering like a whip (Fig.
9). In such forms the flagellum is often very short.
The two flagella, in Trypanoplasma and Trypanophis, are inserted
into the body close to the anterior end (Fig. 8, F, G). They are
quite separate from each other, and while one (that most anteriorly
situated) is entirely free and directed forwards, the other at once
turns backwards and is attached to the convex (dorsal) side of the
body for the greater part of its length. This latter flagellum
terminates in a shorter or longer free portion.
The comparative degree of development of the two flagella in
different cases is worth pointing out, since it is very instructive in
a phylogenetic connection. Starting with Bodo lacertae, from a
type similar to which the biflagellate forms may be derived, both
flagella are of about equal total length, and the trailing one does
not reach the posterior limit of the body. In Trypanophis grobbeni
(Fig. 30) the posterior flagellum is more developed than the
anterior one, and attached to the side of the body, but its free
termination is very short. In Trypano-
plasma borreli the anterior flagellum and
the free portion of the posterior one are
of equal length. Lastly, in T. cyprini
the former is much shorter than the
latter, and shows signs of reduction.
From this condition to its disappearance
is but a small step.
In all other Trypanosomes there is
only one flagellum, which is invariably
attached to the body in the same manner
as the posterior one of the biflagellate
forms. The point of origin of the
flagellum is generally near the non-
flagellate end, but may vary consider-
ably. Although there is usually a free
continuation of the flagellum, it may be
short or lacking (cf. Fig. 34).
Along the dorsal side runs a char-
acteristic fin-like expansion of the body, the undulating membrane
This always begins proximally at the place where the attached
flagellum emerges from the body ; and its free edge is really con-
stituted by the latter, which forms a flagellar border, more or less
sinuous in outline. The membrane may be only narrow, and
chiefly discernible by its well-marked border (Figs. 7, A, G ; 8, c),
or it may be well developed and sometimes thrown into broad folds
or pleats (Figs. 7, r ; 8, A, B). Distally the membrane thins away
.concurrently with the body.
T. lewisi, from a
rat five days after
inoculation to show
the remarkably long
aflagellarend. (From
an original drawing
kindly lent by Dr.
J. D. Thomson.)
212 THE HAEMOFLAGELLATES
Minute Structure. — The body appears to lack any distinct
limiting membrane or1 cuticle. A differentiation of the peripheral
cytoplasm in the form of an ectoplasmic layer, the so-called " peri-
plast," has only been definitely described in a few cases (Prowazek
[68], Wasielewsky and Senn [86]). Nevertheless, it is probable
that in most Trypanosomes there is such a layer, although it may
be, in some forms, only poorly developed around the body generally.
The undulating membrane, however, is certainly largely, if not
entirely an ectoplasmic development. This is usually much clearer
and more hyaline in appearance than the general cytoplasm. The
latter is finely granular or alveolar in character, though its exact
degree of coarseness and density varies in different forms, some-
times even in different parts of the same individual. The cyto-
plasm of male forms is in general clearer and less granular than
that of female ones. The cytoplasm in T. mega and T. karyozeiitton
is rather unusual in structure. In the third of the body on the
aflagellar side of the nucleus, it is very loose and spongy ; in the
other two -thirds, it is arranged in alternating light and dark,
densely-staining bands (" hyaloplasm " and " spongioplasm "), run-
ning more or less longitudinally.
Cytoplasmic inclusions of one kind or another are often to be
found. In many Trypanosomes, deeply -staining granules occur,
which vary greatly in number and size. These granules appear
to be chiefly distributed, as a rule, in the flagellate half of the
body (Fig. 7, B, D). They are of a chromatoid nature, and probably
derived from the nucleus (see Lignieres [54]). In Trypanophis there
are one or two rows of highly refractive, yellowish inclusions run-
ning the length of the body (Fig. 30). It is thought that these
represent collections of fatty or oily substances. In certain forms,
a well-defined, usually oval vacuole is often, though not constantly
present, situated at a varying distance from the aflagellar end (Figs.
7, C, G ; 8, F). There is no reason to doubt that this vacuole is a
normal cell-constituent, for it has been observed in parasites in their
natural (tolerant) hosts under quite normal conditions.
Until recently, very little was known with regard to the
details of nuclear structure. A Trypanosome was merely described
as possessing an unmistakable nucleus, and also a small deeply-
staining element of uncertain significance, situated at the root of
the flagellum, and termed variously " blepharoplast," centrosome,
or micronucleus. It is to Schaudinn that we are indebted for the
revelation of the essential nuclear nature of the latter organella,
its intimate connection with the larger nucleus and the complexity
and differentiation which the whole nuclear apparatus may
exhibit. Since then several workers have brought forward
observations relating to one point or another, which, taken alto-
gether, suggest strongly that the nuclear organisation of Trypano-
THE HA EMOFLA GELLA TES
213
somes in general is based upon a plan fundamentally similar to
that described by Schaudinn in the case of his Avian parasite,
Trypanomorpha noduae. The development and ultimate constitution
of the nuclear apparatus in this type are as follows : —
The account may be commenced with the condition found in an
indifferent ookinete or individual which will become an indifferent (non-
sexual) Trypanosome. Here a single, large compound or double nucleus
is present, consisting of an external portion and of rtn internal, central
FIG. 10.
Development of an indifferent Try-
panosome from an ookinete of indif-
ferent character. (After Schaudinn.)
t.chr, trophonuclear chromosome ;
K.chr, kinetonuclear chromosome ; c,
centrosomic granule ; a.s, first axial
spindle ; o.s2, a.s 3, second and third
spindle ; t. trophonucleus ; k, kineto-
nucleus ; fc.e, kinetonuclear centro-
soine; t.f, trophonuclear centrosome ;
m, myonemes ; /.';, flagelliir border of
undulating membrane (third axial
spindle) ; u3, its proximal centrosome.
portion (Fig. 10, A). The former has eight distinct, peripherally situated
chromosomes ; the latter also has eight separate chromosomes. In the
centre of all is a well-marked centrosomic granule (c). The first change
takes place by the inner body becoming amoeboid and giving up its
material to the outer, surrounding part (B). The result is that the eight
chromatic elements of the former become united, by the aid of the plasti-
noid basis present, with those of the latter, leaving the above-mentioned
grain in the middle. This granule divides in a dumb-bell-like manner,
producing a small axial spindle (c, a.s.), around which the eight compound
chromosomes arrange themselves. These next split, and the halves pass
to either end, forming a diaster which is markedly heteropolar. The
214 THE HAEMOFLAGELLATES
right (or dorsal) half is perceptibly smaller, but denser and more deeply
staining than the other. In this manner, therefore, two distinct nuclear
bodies are formed, of different size and character. They remain connected
together by a fine achromatic thread, representing the original central
spindle, which ends in a small granule near the centre of each. The
larger nucleus, lying nearer the middle of the body, rapidly reconstitutes
itself and enters upon a resting-phase. This nucleus regulates the trophic
functions of the cell, for which reason we have proposed (3) for it the
name trophonucleus.
Meanwhile, the other, smaller nucleus proceeds to give rise to the
characteristic locomotor apparatus of the Trypanosome. It passes forwards
slightly and takes up a position at the periphery of the endoplasm, lying
indeed against the limiting ectoplasm. Its centrosome divides again in
a similar manner, forming another axial spindle (E, a.s 2) at right angles,
as before, to the length of the parasite. Another heteropolar division
next takes place, giving rise to two daughter-nuclei ; these also remain
connected together by the drawn-out central spindle, which join the two
centrosomic granules. The peripheral daughter-nucleus, situated almost
in the ectoplasm, forms yet another spindle (F, a.s3), whose axis is now,
however, longitudinal. This assumes large proportions and spreads
forward to the anterior end of the body, the whole lying in the ectoplasm,
which becomes greatly developed to form the undulating membrane.
The central spindle becomes excentric in position and sinuous in outline,
and strengthens, or rather itself constitutes, the free edge of the membrane,
forming a -flagellar border to it (H, /.&). A supporting framework is
formed by eight myonemes, representing the eight elongated daughter-
chromosomes, four of which are arranged on each lateral surface. The
flagellar spindle does not stop on reaching the anterior end of the body,
but continues to elongate, drawing out with it the undulating membrane,
which narrows and finally thins away. The myonemes then unite with
the spindle to form the free flagellum, the centrosome at the distal end
disappearing as such, but that at the basal or proximal end persisting (c).
By this time the other daughter-nucleus has become rounded off as the
kinetonucleus (k), which regulates all the kinetic activities of the parasite ;
it remains connected with the locomotor apparatus by a delicate thread,
representing the second axial spindle.1
According to Prowazek's recent investigations, the same type of
nuclear structure is also shown by two Mammalian forms, T. lewisi
and T. brucii ; indeed, it is maintained that the system of axial
spindles produced by successive divisions of the karyocentrosome
1 Two other points bearing on the view that the flagellum represents the greatly
elongated axial spindle of a nuclear division may be noted. In Trypanosoma
johnstoni, where there is no free portion of the flagellum, this terminates (at the
limit of the cytoplasm) in a small deeply-staining granule (Fig. 34), perhaps com-
parable to the distal centrosome of such a spindle. Again, Miss Robertson (72)
sums up her account of the origin of the flagella in the development of the flagellate
form from the rounded, aflagellar type in the case of her leech -Trypanosome by
saying, "the two flagella appear to be developed from a pair of arrested mitotic
figures developed out of the distal of the two segments into which the original
kinetonucleus divides."
THE HA E MO FLA CELL A TES
215
is even more elaborate in the former parasite than in the case just
described. Further evidence in support of Schaudinn's view of
the intimate relation and correspondence between the two nuclear
organellae is furnished by L6ger (50), who has observed, in
"ookinetes" of T. barbatiilae (see under "Life-Cycle"), heteropolar
division of a single large nucleus, doubtless leading to the forma-
tion of tropho- and kinetonucleus ; and by Bradford and Plimmer
(6), who have observed the latter element (" micronucleus ") a given
off from the larger nucleus in T. brucii. Perhaps the most striking
confirmation of the essential nuclear character of the kinetonucleus
is afforded, however, by a comparison of this organ ella in Trypano-
plasma borreli, where it is particularly large, and like a nucleus ; in
fact, it was originally regarded as the nucleus (trophonucleus) of
FIG. 11.
Trypanoplauma lorreli, Lav. and Mesn. a.f, anterior flagellum ; p.f, posterior flagellum ; m,
undulating membrane ; T, trophonucleus ; K, kinetonucleus ;' /, fibril (myoneme) ; c, centre-
somic granule at base of flagellum. (After Leger.)
this parasite. Moreover, in addition to the kinetonucleus, and
immediately in front of it, two centrosomic granules can be
distinctly seen, one at the base of each flagellum (shown clearly in
Lager's figures, Fig. 11, B, c). In Tnjpaiwsoma also, in many cases,
the root of the flagellum is not actually connected with the kineto-
nucleus, but terminates before reaching it in an unmistakable
granule, which we have found to stain much darker than the
flagellum. Lastly, in this connection the writer has been very kindly
permitted by Prof. Minchin to make use of two figures of his (about
to be published) of Trypanosoma grayi undergoing division, in which
centrosomic granules, associated with the kinetonuclei, are clearly
1 It is necessary to point out that the kinetonucleus is not a "micronucleus,"
in the sense in which this term is always used as applying to that body in the
Tnfusoria. In the Trypanosomes both nuclei are equally essential and functional,
in somatic life as well as in sexual reproduction.
216 THE HAEMOFLAGELLATES
shown (Fig. 12). An additional feature of interest is the presence
of a well-developed axial spindle, still connecting the two tropho-
nuclei (which have divided last), and ending in a granule inside
each, which is doubtless the trophonuclear centrosome. In other
cases (e.g. T. remaki, Trypanoplasma borreli, Trypanopliis) as well, a
large, distinct granule has been described in the centre of the nucleus,
which very probably represents the trophonuclear centrosome
(karyocentrosome). To sum up, the above facts leave little reason to
doubt (a) that the kinetonucleus of a Trypanosome is not merely
an extranuclear centrosome,1 but a true nucleus, homologous with
and equivalent to the trophonucleus, the two being specialised for
different functions ; and (b), that distinct centrosomes are associated
with both nuclei, the trophonucleus possess-
ing an intranuclear one, while in connection
with the kinetonucleus there is an extra-
nuclear one (at the base of the flagellum)
and perhaps also an intranuclear one (accord-
ing to Schaudinn).
Both nuclei vary greatly with regard
to their position in the body, in different
forms, as will be seen on comparing the
figures given. As a rule, the trophonucleus
PIG. 12. lies somewhere near the middle of the body,
Trypanosorna grayi, dividing, and the kinetonucleus near the aflagellar
nlnTdrlwtfti So^SS end, being farther from it in proportion as
somic granules are seen one the extremity is tapering. In some cases,
above each kinetonucleus. ' a. . . '
however, at all events during certain periods
of life, the two nuclei lie close together centrally, at times being
actually in contact (cf. T. inopinatum, Fig. 8, C ; T. " iransvaaliense,"
Fig. 33 ; T. rotatorium, Fig. 8, B; and T. lewisi, young forms, Fig.
21, E). The trophonucleus is generally ovoid in shape, the longer
axis being longitudinal, but in the Trypanosome described by
Button and Todd from Senegambian birds, and also in T. hannae,
the long axis is transverse to that of the body (Figs. 7, G; 35).
As regards its minute structure, the trophonucleus appears generally
to consist of an aggregation of chromatin grains embedded in a
plastin-like matrix. No mention is usually made of a nuclear
membrane or reticulum. In his account of Trypcmoplasma borreli,
it may be noted, Le"ger (49) has described eight dumb-bell-shaped
chromosomes. An unusual appearance of the trophonucleus has
been observed in one or two instances (T. brucii, Stuhlmann and
Miss Kobertson ; T. raiae, in the leech, Miss Robertson). In these,
1 Salvin-Moore and Breinl, in their account of the " cytology of the Trypanosomes "
(Ann. Trap. Med., Liverpool, 1907), continue so to regard this organella, in spite of
all the evidence to the contrary, much of which (e.g. that furnished by Trypanoplasma)
they entirely overlook.
THE HAEMOFLAGELLATES 217
this organella is very much elongated, and the chrottiatin is arranged
in the form of a ladder of parallel rods or pairs of granules (chromo-
somes ?). There is not much to note with regard to the kineto-
nucleus. In a solitary instance, namely, T. equinum, it is extremely
minute and difficult to distinguish ; it appears as a dot-like thicken-
ing at the root of the flagellum (Fig. 7, r>). In this case, the
organella has apparently become reduced.
The occurrence of prominent myonemes in the undulating
membrane of Trypanomorpha, and their nuclear origin (as " mantle-
fibrils "), has been already described. According to Prowazek
{I.e.), a similar development occurs in both T. lewisi and T. brucii ;
here the myonemes lie in the general ectoplasm of the body, f oni-
on each side, but they are very delicate and difficult to make out.
In two or three other parasites longitudinal striations, comparable
to muscle-fibrillae, have been observed ; nothing is known, how-
ever, about their origin. Thus in Trypanoplasma borreli there are
two, one on each side of the body, which start in front and run
backwards more than half-way, finally joining ventrally (Fig. 11,
•c, /). Again, in Trypanosoma, soleae (Fig. 8, j), the ribbed forms of
T. rotatorium (Fig. 37, A), and in T. avium (according to Novy and
M'Neal), myoneme striations are well marked.
4. BIOLOGICAL CONSIDERATIONS.
A. Movement. — In general, Trypanosomes are extremely active
.organisms. According to the manner in which they are produced,
two kinds of movement can be distinguished : (1) displacement of
the body, usually rapid ; and (2) creeping and pushing movements,
by means of flexion, extension and contraction of the body, etc.
The latter kind are brought about, in all probability, by the super-
ficial myonemes mentioned above ; they are, in fact, often comparable
to " euglenoid " movements (cf. the flexion movements of sporozoites).
In all such cases, it is important to note, the non-flagellate end
moves first.
In active movements of displacement, the flagellar extremity
generally leads the way. The motion may be very rapid and
relatively considerable, as in T. lewisi ; or sluggish and inconsider-
able, as in T. brucii, whose powers of active displacement appear
slight or else little used. There is some difference of opinion as
to whether the undulating membrane or the flagellum plays the
principal part in this locomotion. The flagellum doubtless acts to
a certain extent as a tractellum, especially in cases of very rapid
movement. In Trypanoplasma, in which, of course, the anterior
end goes first, the principal organella concerned, according to Ledger
(I.e.), is the undulating membrane, whose rapid vibrations produce
.quickly succeeding waves, running backwards. The oscillations
THE HAEMO FLAGELLATES
may be continued into the posterior flagellum, which then acts as a
pulsellum ; Leger thinks, however, that this flagellum functions
chiefly as a rudder (Schleppgeissel). The anterior flagellum is not
greatly, if at all, concerned in the movement.
All Trypanosomes undergo, more or less continually, a vibratile
or undulatory motion of the membrane, which may take place in
either direction. Among the elongated Piscine forms, movements
of contortion are much in evidence, the body being frequently
coiled up on itself. In many Trypanosomes, again, especially the
more spirochaetiform ones, the membrane appears spirally wound
round the body, this being due to a more or less pronounced
torsion of the latter, which gives the animals a corkscrew-like motion.
B. Agglomeration. — This characteristic phenomenon of Trypano-
somes occurs chiefly or only upon the advent of unfavourable
biological conditions in the surrounding medium. In the normal
blood or other humour of Vertebrate hosts agglomeration has only
been observed in one or two cases, when it has been termed auto-
agglomeration. Agglomeration is readily brought about artificially
in various ways ; e.g. when drawn blood containing the parasites is-
kept for some time at a low temperature ; when sera of other
animals, especially of animals which have been once or twice inocu-
lated with the particular Trypanosome, are added to fresh blood ;
or by the addition of chemical solutions.1
Agglomeration generally commences by two Trypanosomes
coming together and joining (Fig. 14, A) ; and the union may some-
times remain only binary. In most cases, however, the agglomera-
tion progresses rapidly, a number of parasites collecting round a
common centre and forming a multiple union or rosette (Figs. 13 ;
14, B). Such a cluster or rosette is known as a primary agglomera-
tion, and may consist of as many as a hundred individuals ; some-
times the rosettes themselves become grouped together to form large
tangled masses. In a natural (as opposed to an artificial) mediumr
agglomeration of a particular form of Trypanosome takes place,
typically, by the same extremity. In Trypanomofpha noctuae, accord-
ing to Schaudinn, this is the flagellate (anterior) end ; i.e. the
parasites unite with the flagella pointing towards the centre (Fig. 1 3).
In Trypanosoma, on the other hand, the union is by means of the
aflagellar end.2
1 For fuller details the reader is referred to the works of Laveran and Mesnil
(37, 43), Lignieres (54), Thiroux (83), and others.
2 In artificial cultures, clusters are frequently observed in which the arrangement
of the parasites is not constant, even in the same species ; that is to say, some-
times the Trypanosomes have their flagella at the periphery, while at others the
flagella are centrally directed. It appears, however, that two entirely different pro-
cesses are concerned. In some cases, at any rate, those clusters which have the
flagella pointing centrally are instances not of agglomeration, but of rapid successive
division, where the parasites remain more or less in contact and form large colonies.
This has been well brought out by Novy and M'Neal (62, 63), Thiroux, and others.
THE HAEMOFLAGELLATES
219
This peculiar feature of Trypanosomes differs in one or two
important respects from the somewhat similar phenomenon of
agglutination in Bacteria. The Trypanosomes do not in the
slightest lose their mobility during the process. Each individual
continues active movements, its flagellum lashing away at the
periphery, and appears to be making strenuous endeavours to escape.
Again, a rosette is able to become disagglomerated ; a bacterial
cluster or agglutination, on the other hand, is never dissolved.
Disagglomeration is appar-
ently in consequence of the
retention of the power of
movement by the parasites.
Sometimes all the indi-
viduals, apparently quite
unaltered morphologically,
FIG. 13.
Agglomerated cluster of
male forms of Trypanomor-
pha noctuae in the intestine
of the gnat. (After Schau-
dinn.)
FIG. 14.
A, binary union or agglomeration of T.
lewisi. B, primary rosette of the same parasite.
(After L. and M.)
become thus dispersed. At other times disagglomeration is only
partial, a certain number of the more feeble Trypanosomes remaining
together and slowly dying. If the agglomerating serum is very
powerful, however, or if the biological conditions remain unfavour-
able, the rosette does not break up and the parasites at length
die off.
The significance of the process has yet to be ascertained. By
some it is regarded as a purely involuntary proceeding on the part
of the parasites, and brought about more or less mechanically. A
suggestion put forward by Lignieres (54) is not without interest,
particularly when the recent work of Calkins on the essential
meaning of fertilisation is borne in mind. This author considers it
quite probable that, as a result of the close intimacy, a molecular
interchange goes on between the associated individuals, which may
have a stimulating or recuperative value.
C. Abnormal and Involution Forms. — Involution and degenerative
phases of Trypanosomes have received attention and acquired an
220
THE HAEMOFLA CELL A TES
importance altogether undeserved, owing chiefly to the fact that
many of these parasites have been studied, so far, only in strange
and unaccustomed hosts — hosts to which they are unadapted, and
for which they, on their part, prove markedly pathogenic.
Trypanosomes appear to be, in most cases, able to support, for a
longer or shorter period, unfavourable conditions of environment,
whether due to the reaction of the host itself or to the transference
of the parasites to a strange medium. Sooner or later, however,
the organisms feel the effects of such changed circumstances and
Flo. 15.
Involution and degeneration forms of different Trypanosomes. A-E, T. gamble-use (A, C, and
B after Bruce and Nabarro ; B and D after Castellani). P, K-P, T. brucii (F after Br. and
PI. ; K-P after L. and M.). G-J, Q and R, T. equinum (after Lignieres.) 8, T. brucii, plas-
morlial mass, from spleen pulp (after Br. and PI.).
become markedly altered. The strange forms and appearances
frequently described are probably for the most part l abnormal ; i.e.
they do not represent phases in the typical life-cycle, but are vary-
ing stages in a process of degeneration. Nevertheless, it by no
means follows that the parasites rapidly die off. On the contrary,
many of these involution-forms, on entering the blood of a fresh
host, are able to infect it, though they may even have been kept for
some time in artificial surroundings.
The course which involution takes varies in different cases, but
the process generally follows one or another of three lines, which
1 See footnote to p. 222.
THE HA E MO FLA CELL A TES
221
may occasionally be met with in combination in any given abnormal
form. (a) Chromatolysis. Here there is either a more or less
complete loss by the nucleus (usually the trophonucleus) of its
chromatic constituents, which pass out into the cytoplasm leaving
only a faintly staining plastinoid basis (Fig. 15, A) ; or else direct
fragmentation of the nucleus occurs (F-j).1 (b) Vacuolisation. The
frequent presence of a vacuole in many Trypanosomes, which is
A.
FIG. 16.
Involution and degeneration forms (continued). A-C, T. bntcii, after Br. and PI. ; D-G, T.
iiomiiiense, after Castellani ; H, T, briicii, after Martini ; J, K, T. equinum, after Voges ; L, T.
brucii, agglomeration-cluster, commencing to form a plasmodium, after I3r. and PI.
probably to be regarded as a normal cell-organella, has been men-
tioned above. The first indication of abnormality in this direction is
perhaps afforded when the vacuole increases very greatly in size (Figs.
15, E ; 16, E). Other, irregular ones may appear in the cytoplasm,
when the involution becomes pronounced in character (Figs. 15, C;
16, G). (c) Change of form. This is, from the weird forms often
resulting, the most obvious line of involution. Alteration in shape is
generally accompanied by an increasing loss of mobility. In the
1 In certain of these cases it is possible that something in the nature of chrom-
idial formation may be going on, leading to nuclear readjustment.
222 THE HAEMOFLAGELLATES
case of single forms the body becomes stumpy (Fig. 15, C-E), losing
almost entirely its trypaniform shape, and ends by being ovoid or
like a ball (c, H, L) ; l the flagellum is limp and inactive and partially
coiled up (j). In other cases, quite irregular multiplication occurs,
accompanied by incomplete cytoplasmic division, leading to the forma-
tion of distorted multinucleate and multiflagellate bodies (Fig. 16,
A— G). Lastly, various fusion -forms may be met with, masses of
Trypanosomes gradually losing their distinctness and constituting
large plasmodia (Figs. 16, L; 15, s), made up of a great number of
nuclei embedded in a common cytoplasmic matrix.
If the organisms remain subjected to the unfavourable influences,
or if involution has reached too advanced a stage, death and dis-
integration result. The cytoplasm is the first to disappear, becoming
hyaline and colourless, and refusing to stain up. The nucleus
rapidly follows suit. The most resistant elements are the kineto-
nucleus and flagellum, which may persist long after other traces of the
organism have vanished (Fig. 15, p), the former as a little thickening
at one extremity of the latter ; sometimes the flagellum alone is left.
5. MULTIPLICATION.
Binary longitudinal fission is, probably, of universal occurrence,
and appears to be the usual method of multiplication ; though
Trypanosoma lemsi, at any rate, possesses another method in
addition, namely, rosette -like segmentation.
The process of fission begins with the division of the nuclear
and locomotor apparatus, but the actual order of division of these
different organellae appears to be very inconstant and variable.
As a rule, the kinetonucleus leads the way, but sometimes the
trophonucleus may. The duplication of the flagellum begins at
its proximal end, that which is in relation with the kinetonucleus.
Until lately the process has always been considered as an actual
longitudinal splitting of the flagellum, following upon the separation
of the two daughter-kinetonuclei. Now and again examples are
met with in which the duplication of the flagella has taken place
before the kinetonucleus has divided. It seems probable that it
is really the division of the kinetonuclear centrosome which is the
essential prelude to the division of the locomotor apparatus. This
flagellar splitting has been described either as extending to the
distal end of the undulating membrane, after which the two halves
separate (Fig. 17, c), or as being practically limited to the root-
1 It is here, if anywhere, that there might be a possibility of regarding as involution-
forms phases which really belong to the normal life-cycle ; e.g. rounded-off, resting
phases (cf. the " resistant forms " of Holmes and others). In such, however, the
flagellum would doubtless be absent, while the nuclear elements and cytoplasm would
be as usual ; in fact, the parasites might well show a resemblance to the Leishman-
Donovan bodies (cf. pp. 255 et seq.).
THE HAEMOFLAGELLATES
223
portion, which becomes thickened and then divides, one half break-
ing away as a new, short flagellum, whose further growth is basal
and centrifugal (Fig. 20, D). Schaudinn found, however, that in
A. C
FIG. 17.
Stages in binary longitudinal fission of T. brucii. (After Lav. and Mesn.)
Trypanomorphi noctuae the whole of the flagellum, etc., is developed
quite independently from the daughter-kinetonucleus, and laid
down alongside and parallel with the old locomotor apparatus ;
moreover, Prowazek (I.e.) and also M'Neal (56) maintain that the
same is the case in T. lewisi. Nevertheless, in many cases it seems
hardly possible to doubt that there is actual splitting of the
flagellum ; where, for in-
stance, the two new flagella
of the proximal part of the
body appear to actually
join arid continue as one,
yet undivided flagellum
(as seen in Fig. 17, A
and B). Again, even
where a daughter-flagellum
is separate from the main
one, the course of the two
is often so exactly parallel
that their origin by longi-
tudinal fission is highly
probable.
So far, we have not much knowledge with regard to the
cytological details of nuclear division. Prowazek has given a
description of the process in T. brucii. The kinetonucleus becomes
thickened and spindle -like (Fig. 18, A). Subsequently it becomes
Flo. 18.
Details in the nuclear division of T. brucii.
(After Prowazek.)
224
THE HAEMOFLAGELLATES
dumb -bell -shaped, after which the two halves become farther
separated, remaining connected only by a short thread (B).
The chromatin of the trophonucleus is arranged in eight rather
elongated chromosomes, which next begin to divide in a similar
dumb-bell-like manner (Fig. 18, c). The trophonuclear karyosome
(karyocentrosome) has frequently divided by this time ; but in
one instance Prowazek observed it much drawn out and functioning
as an intranuclear division centre (n), the chromatin having
become aggregated around its ends.
In her account of T. raiae in Pontobdella Miss Robertson (I.e.)
has gone at length into the question of nuclear division. The
kinetonucleus appears to divide by a simple kind of mitosis though
FIG. 19.
A-D, stages in the binary longitudinal tission of 7'. r</» inn m ; K, multiple fission in the same
parasite ; F and G, binary and multiple division in T. cfiuiperdum. (After Lignieres.)
the details are extremely obscure. The trophonuclear division also
takes place by a simple kind of mitosis, but shows a well-defined
achromatic figure (comparable to a series of axial fibrils). This
probably arises from the trophonuclear centrosome. The figures
showing the later phases of the process convey quite the same idea
as does Fig. 12 of T. grayi. In fact, this case also appears to
conform to the same general plan as those above described.
The division of the cytoplasm takes place last. In the great
majority of forms this is equal or sub-equal, and the two resulting
daughter-Trypanosomes are of approximately the same size (Figs.
17 ; 19, c). Although the cytoplasmic fission usually begins at the
flagellar end, it may start at the opposite extremity (cf. Fig. 19, D).
In some instances (Fig. 19, E and G) the longitudinal fission is
225
multiple, the original individual giving rise, simultaneously, to three
or four descendants.
T. lewisi differs from most Trypanosomes in that the cytoplasm
generally * divides in a very unequal manner (Fig. 20). Indeed,
the process is more comparable to budding, since the larger or
parent individual may produce, successively, more than one
FIG. 20.
Unequal division in T. lewisi. m, parent-individual ; <7, daughter-individual ; rf1, daughter-
individual dividing, x 2000. (A-E after Lav. and Mesn. ; F after Wasielewsky and Senn.)
daughter-individual ; moreover, the progeny may themselves sub-
divide before separating, the whole family remaining connected
together by the non-flagellate end (Fig. 20, E and F). In this type
of division, it may be noted, the kinetonucleus comes to lie alongside
the trophonucleus, or even passes to the other side of it (i.e. nearer
the flagellar end). This method of division forms, as it were, a
1 Swingle (81) lias recently found that T. lewisi may also divide by equal binary
fission ; and in such cases the two flagella may lie on opposite sides of the body.
15
226
THE HAEMOFLAGELLATES
transition between binary fission and the other characteristic method
of T. lewisi, namely, segmentation or rosette-formation (Fig. 21).
The chief difference is that, in the latter, no parent-individual is
recognisable, the segmentation being equal and giving rise to a
rosette of equal daughter-Trypanosomes.
The small parasites resulting from either of these modes of
division (Fig. 21, E) differ from typical adults by their stumpy, pyri-
form shape, the position of the kinetonueleus near the fiagellar end
of the body, and the absence, during the first part of their youth,
of an undulating membrane. At this period they have a somewhat
Herpetomonas-like aspect. These young individuals can them-
A-D, segmentation (rosette-formation) in T. lewisi ; in C nuclear division lias finished and
the daughter-nuclei (of both kinds) have taken up a superficial position, while the cytoplasm
lias become lobulated at the periphery, prior to the formation of the daughter-Trypanosomes.
E, daughter-individual ; F, one dividing, x 1750. (After L. and M.)
selves multiply by equal binary fission, giving rise to little
fusiform parasites ; and, with growth, these gradually assume the
adult appearance.
6. THE LIFE-CYCLE OF TRYPANOSOMES.
It may be safely said that this remains, even to-day, one of the
most difficult and most debated questions among the whole of the
Protozoa, in spite of the amount of work, of one kind or another,
which has been contributed to the subject during the last few
years. When the present writer compiled his Review of the
Haemoflagellates (3) some years ago, Schaudinn's remarkable
observations had been, to all appearance, amply corroborated in
various directions by the testimony of the Sergents (77), Billet
(4, 5), Brumpt (9), Leger (50), and Rogers (94) ; in short, the
THE HAEMOFLAGELLATES 227
whole trend of research pointed at the time to a very complex
life-cycle of the Haemoflagellates and to a close connection with
the Haemosporidia. Since then, however, owing in a great
measure to the work of Novy and M'Neal on the Trypanosomes of
birds (62) and of mosquitoes (63), the results obtained by
Schaudinn have become, to a large extent, discredited ; these
authors maintaining that they are capable of a quite different
interpretation. Moreover, influenced by their work on Insectan
Flagellates, Novy and his colleagues have gone to the other
extreme and expressed their belief not merely that Haemoflagellates
and Haemosporidia are entirely distinct, but also that the Trypano-
somes of Vertebrates do not undergo any true development or part
of their life-cycle in the Insectan host. This latter view, at all
events, is, AVC think, shown to be incorrect by the most recent
research, which, as above mentioned, seems all in favour of an
alternate, Invertebrate host, one of the most important indications
being with regard to the specificity of the latter — a point of the
utmost consequence in its bearing upon investigations of this kind.
Leaving aside for the moment a consideration of Schaudinn's
celebrated memoir, it Avill be best to give first a brief account of
the results obtained in this connection by different prominent
researchers, to other aspects of whose work reference has been
previously made.
Dealing first with Trypanosomes of cold-blooded Vertebrates,
the earliest important observations are those of Le"ger (50), relating
to Trypanoplasma varium and Tri/panosoma barbatulae of the loach.
Leger distinguishes ordinary ("indifferent") and larger, more
granular (probably female) forms of the Trypanoplasma in the
blood of the fish. When a leech (Hemiclepsis sp.) was allowed to
suck blood containing only these parasites, which thereupon passed
into its stomach, the indifferent forms degenerated and perished,
while the female ones became massive and showed nuclear changes,
preparatory, Leger thinks, to a sexual process. At any rate, after
some days, the intestine of the leech contained numerous little
narrow Trypanoplasms, of which some, very filiform, perhaps
represented male forms, while others possessed a kind of beak or
rostrum in place of the anterior flagellum, which made them
resemble Trypanosomes. The development of Trypanosoma bar-
batulae in another leech (Piscicola) showed a certain amount of
agreement with that described by Schaudinn in the case of his
Avian Trypanosome in the gnat (Culex). Eighteen hours after
the leech had fed on blood containing exclusively T. barbatulae,
pyriform bodies lacking a flagellum (" ookinetes ") were found in
the intestinal contents. Some of these had a single large nucleus
ii.e, a compound nucleus) ; others had two nuclei, one smaller than
228 THE HAEMOFLAGELLATES
the other. Four days later the intestine contained numerous
Trypanosmes which could be readily distinguished as belonging to
one of Schaudinn's three types — namely, indifferent, male, or female.
The male forms are very elongated and slender, provided with a
minute rostrum at the aflagellar end, and with a well -developed
flagellum at the opposite extremity, which renders them extremely
active ; they also creep or crawl with the rostrum in front. Their
cytoplasm is very clear and usually lacks granulations. Female
forms, on the contrary, are large and broad, with deeply staining,
usually granular cytoplasm ; the flagellum is only feebly developed
and the movement is sluggish. The indifferent individuals occupy
in most respects an intermediate position between the other two
types. A point of importance is that the kinetonucleus frequently
lies in about the middle of the body, and may be close to the
trophonucleus. There can be no doubt, it may be here remarked,
that these different sets of forms are of regular occurrence in, at
any rate, certain Trypanosomes. Since Schaudinn first described
them several observers have recognised them, in some instances in
the Vertebrate host, but always more sharply differentiated in the
Invertebrate. In general, the three types show the same charac-
teristics as noticed in the case of T. barlatulae. The indifferent
forms, Leger states, underwent active multiplication, by equal
fission ; those females which divided did so very unequally, by
a process somewhat like budding. The manner and form in which
the parasites passed back into the fish were not ascertained.
'In his valuable contributions on the behaviour of Piscine
Trypanosomes in leeches, Brumpt (11) has noted developmental
phases of T. granulosum of the eel in Hemidepsis. Some hours
after arrival in the stomach of the leech, all the parasites become
pyriform, and by the position of the kinetonucleus close to the
trophonucleus recall Lager's Crithidia-typQ (see below). By active
multiplication, an enormous number of little forms are produced,
which by the end of forty-eight hours have nearly all passed into
the intestine. Here they rapidly become elongated, assuming a
Herpetomonad-form, which may be retained for several months.
Some, however, by the end of seventy-two hours, have given rise to
true Trypanosoma-forms, with typical undulating membrane, which
pass forwards towards the stomach, and may be found accumulated
in the foremost stomach-coeca and in the proboscis-sheath by the
fifth day. These are the forms which are inoculated into the eel,
becoming by simple elongation ordinary T. granulosum again.
Miss Robertson has published (72) some interesting observations
on a Trypanosome met with in Pontobdella muricata, which she
regards as T. raiae. This view is rendered extremely probable from
the fact that Brumpt (10) has found that T. raiae does develop in
Pontobdella. According to both authors the earliest phases occurring
THE HAEMOFLAGELLATES 229
are rounded forms with both nuclei but no locomotor apparatus —
comparable to ookinetes, in short (cf. T. barbatulae above). These
individuals, says Miss Eobertson, which divide in this condition
fairly actively, gradually disappear from the crop and are found
only in the intestine. Here they develop a locomotor apparatus,
but persist for some time in a Crithidia-]\ke form ; they are of
varying size and may be very small. Later on, these individuals
take on a more or less typical Trypanosome-like, or, as we have
previously termed it, trypaniform character, with the kinetonucleus
in the aflagellar half of the body, though its actual position varies
greatly. These trypaniform individuals are of two main types,
which appear, however, to be connected by intermediate grades.
One kind is relatively very broad, with a relatively small kineto-
nucleus, but usually with a fairly long flagellum. The other type
is a long slender Trypanosome, with a large kinetonucleus, but the
free flagellum is not, as a rule, very long. The constitution of the
trophonucleus presents an unusual condition ; it is very much
drawn out, and the chromatin is arranged in a number of transverse
rods or bars (perhaps comparable to chromosomes) arranged more
or less parallel, like a ladder (cf. author's note on T. brucii above,
p. 216). About the middle of digestion, these Trypanosomes occur
chiefly in the intestine, but also in the crop, often in large numbers.
At a later period, a still more slender, practically thread-like form is
developed, which is met with chiefly in the proboscis, though also,
apparently, in the intestine. This type, which differs rather from
the last, appears to die off if it remains in the leech, and taking
this in conjunction with the occurrence of these individuals in the
proboscis, the inference is that this is the form in Avhich the
parasites are inoculated into the fish. At the close of digestion,
a number of very small forms are always to be seen, either in a
rounded (probably resting) condition or in a very early Crithidial
phase. These seem to be persistent forms, through which the
leech retains the infection.
Miss Robertson discusses the likelihood of the two contrasting
trypaniform types above described representing male and female
individuals, but for several reasons hesitates to accept this view.
However this may be, it is more probable that conjugation itself
takes place soon after the transfer of the parasites from one host to
the other, i.e. after the arrival in the Invertebrate ; and that the
ookinete form is the immediate result of the process. This is
suggested by Lager's work on T. barbatulae, as well as by Keysse-
litz's account of the life-cycle of Trypanoplasma borreli (27). It
is also regarded by Prowazek (68) as being the case in T. leivisi, in
the louse.
According to Keysselitz, male and female gametes can be
readily recognised in the blood of the fish (carp), the conjugation
230 THE HAEMO FLAGELLATES
taking place in the leech, after various regulatory or matura-
tion processes have been undergone. The copulae give rise to
the three general types, distinguished principally by nuclear
differences.
In the case of T. lemsi, Prowazek states that soon after reaching
the mid-gut of the louse, the parasites undergo reduction of the
nuclear apparatus, by which the number of chromosomes is said
to be reduced from sixteen to four. The gametocytes (parent-
individuals of the gametes) are not strikingly differentiated from
one another, but in the formation of the microgamete from the
male form, the body becomes diminished in size, its nucleus
(trophonucleus) very elongated and at first spirally twisted, then
band-like, while also the cytoplasm stains differently from that of
the female element (megagamete).
Coming now to what is known of the development of Mam-
malian Trypanosomes in Tsetse -flies (Glossinae), we have first to
mention the knowledge obtained by Minchin, Gray, and Tulloch (59)
with regard to T. gambiense in G. palpalis. This, unfortunately, ia
largely of a negative character, owing in all probability (as we have
seen earlier) to this species of fly not being the correct alternate
host, but one in which the attempts of the parasite to continue its
life-history are, for some reason, unsuccessful. Nevertheless, the
important observation that the types already recognised as male
and female in the blood of the Vertebrate at first greatly pre-
dominate, with, moreover, a much more marked differentiation
of sexual characters and without any forms intermediate in
type, is also strongly in favour of the idea that conjugation
occurs, in general, soon after the arrival of the Trypanosomes in
the insect.
No mention is made by Stuhlmann (80), in his highly interest-
ing account of T. brudi in G. fusca, of the occurrence of any similar
phases, or of anything in the nature of ookinetes, at the beginning
of the infection. The first individuals found by this investigator
were of the indifferent type, occurring in large numbers in the
hinder part of the gut, two to four days after infection of the fly.
It seems probable, however, that Stuhlmann missed some early
essential phases of the development, since, as said above, Le"ger
found ookinetes of T. barbatulae eighteen hours after feeding, while
Minchin and his collaborators say that the sexual forms were best
developed after about twenty-four hours, while by the end of forty-
eight hours a type of more indifferent character was making its
appearance. According to Stuhlmann, the indifferent parasites
apparently spread forwards through the mid-gut, but usually pass
right forward only when the flies are fed again (from an uninfected
animal). By this means the presence of the Trypanosomes in the
proventriculus was obtained, and in the "long" form, quite similar
THE HAEMOFLAGELLATES 231
to the type occurring in the proventriculus and oesophagus of freshly
caught " wild " flies.
This type manifestly corresponds to Miss Robertson's very
slender forms in the front part of the gut and proboscis of the
leech ; the agreement extends to the ladder-like arrangement of the
chromatin (chromosomes ?) of the trophonucleus. Whereas, how-
ever, in T. raiae, it is these forms, or their derivatives, which appear
destined to return to the fish, Stuhlmann found, in the proboscis
of freshly caught Tsetses, little Crithidial forms ("small" forms),
with the kinetonucleus alongside, or on the flagellar side of the
trophonucleus.1 Stuhlmann regards these individuals, which he was
unable to obtain in artificially infected flies, as representing the
phase in which T. brutii is transmitted to the Vertebrate ; though
lie states that the long forms seem to degenerate in the pro-
ventriculus after a time (as well as the small ones). In no case,
unfortunately, was he able to actually infect a Vertebrate by means
of either kind, which suggests that there is some other, as yet
unknown, factor or condition concerned in this perplexing question.
Stuhlmann describes and figures certain phases found in one case
in the proventriculus of an artificially infected fly, which he thinks
are perhaps indicative of conjugation. In all the stages figured,
the cytoplasmic body of the parasite is single ; the nuclear and
locomotor organellae, on the other hand, show different conditions
from single to double. Of course, here as in so many other cases,
it is entirely a matter of the sequence in which the figures should
be taken. Stuhlmann's chief reason for his interpretation is that,
in what he regards as the earlier stages of union, the flagella lie on
opposite sides of the body ; whereas, in the usual mode of division,
the two flagella lie on the same side of the body. Still, Stuhlmann
himself agrees that the condition may be only one of an unusual
mode of division ; and this seems the more likely explanation, for
such a mode of division has been observed in T. lewisi.2
That the course of a Trypanosome life-cycle may take, however, a
quite different direction from that outlined in the above instances is
proved unmistakably by Minchin's valuable investigations on Trypano-
soma graiji (57 and 58), which led him to the unexpected discovery
of the encystment of this form in the proctodaeum of G. palpalis.
Minchin recognises three well-marked types of this Trypanosome
in the fly. (a) The ordinary type, having a multiplicative function,
and probably giving rise to the swarm of parasites often found. It
is usually of large size, and shows great variability, especially in
the position of the kinetonucleus. While generally a little in front
(i.e. on the flagellar side) of the trophonucleus, it may be alongside,
1 For an account of the proboscis - forms recently described by Roubaud, see
Postscript, p. 261. 2 Cf. footnote, p. 225.
232
THE HAEMOFLAGELLATES
or even behind it (i.e. nearly terminal at the afiagellar end), though
it is not often in the last position. Minchin thinks this last form
most nearly represents that in which T. grayi occurs in its Vertebrate
(probably Avian) host. The second type (b} is constituted by
slender, often greatly elongated individuals, with well-developed
undulating membrane and flagellum. Minchin was at first inclined
to regard these as male forms ; but from their occurrence in one
case in remarkable numbers in the proctodaeum, to the exclusion
almost entirely of any other kind, he has since thought this view
to be unlikely. The primary habitat of the slender type is the
proctodaeum, from which region it may extend forward through
the intestine and stomach of the fly. (c) Small, very narrow forms,
of a typical Herpetomonas-Yike structure, practically lacking any
undulating membrane (Fig.
22, a), which stain more
faintly and appear much
more delicate than parasites
of type (b); the kinetonucleus
is often relatively large.
These individuals were found
in the proctodaeum, and,
rarely, in the hinder intes-
tine ; they are apparently
derived from young forms of
the indifferent type, pro-
duced by rapid multiplication
in the hinder part of the
intestine.
It is this Herpetomonad
type which undergoes en-
cystment. In cyst-formation
the flagellum becomes
shortened and at the same
time apparently thickened. The cyst begins to appear as a layer
of substance, probably of a slimy or mucoid nature (cf. Prowazek's
" Schleimcysten " in the case of Herpetomonas muscae-domesticae
[69]), which forms a cap at the aflagellar end (Fig. 22, b). These
two processes continue until, on the one hand, the flagellum is
completely retracted, and, on the other hand, the body is enveloped
in a pear-shaped cyst (c), which is at first incomplete at the pointed
end. The flagellum appears next to become retracted into a pink-
staining vacuole (cf. the opposite process in the formation of the
flagellar phase of Leishmania (Piroplasma) donovani) ; finally, the
flagellar vacuole fades away, the cyst meanwhile closing up.
Eventually there results an oval or circular cyst, containing hyaline
cytoplasm and the two chief nuclear masses (d). In this guise,
FIG. 22.
Encystrnerit of the narrow, Herpetomonad form
of Trypanosoma grayi. (After Minchin.)
THE HAEMOFLAGELLATES 233
presumably, T. grayi passes into the outer world, to be swallowed
subsequently by its alternate host.1
Comparing T. grayi with T. Irucii, an essential point of contrast
is at once noticed. In the first-named, the small, Herpetomonad
forms, which have the function of propagating the infection to a
fresh host, occur mainly in the proctodaeum and leave the fly per
<ui urn. In the latter, on the contrary, the small, Crithidial forms,
which are compared by Minchin with those of T. grayi just men-
tioned, were found almost exclusively in the proboscis ; moreover,
no Trypanosomes of any kind Avere seen in the hindermost part of
the gut (proctodaeum). Hence the propagation of T. Irucii would
appear to be just as certainly by the inoculative method as that of
T. f/rayi is by the contaminative one. Further, just as there is at
present no evidence of contaminative infection in T. brucii, so there
is none of inoculative infection in T. grayi ; for although Minchin
says that the slender type, which he also thinks is a propagative
form, was met with farther forward than the Herpetomonad type,
it was not met with farther forward than the stomach. And this
is as far as our knowledge goes up to the present.
Schaudinn's Work on Haematozoa of the Little Owl.
There remains for consideration the remarkable research of the
late Fritz Schaudinn on certain parasites of Athene nodua and Culex
pipiens, namely, I'rypanomorpha (Trypanosoma) noctuae and " Try-
panosoma " (Lemocytozoon, Spirochaeta) ziemanni. Exigencies of space
preclude a detailed account of this work, only the main outlines
of which can be given here, but a full description will be found in
the writer's article on the Haemoflagellates (3).
Taking first Trypanomorplw, noctuae, the life -cycle may be con-
veniently commenced with the motile copula or ookinete resulting
from conjugation in the stomach of the gnat. While the nuclear
fusion of the two sets of elements (kinetic and trophic) derived
from the original gametes is being completed, leading to a single,
large, compound nucleus, the ookinete is getting rid of unnecessary
material, such as the pigment-grains and reduction-nuclei left over
in the cytoplasm (Fig. 10, A, B). Even in the ookinete stage,
Schaudinn recognises the three types of individual, indifferent,
male, and female, distinguishable by differences in the size of
the nuclei relative to the cytoplasm, and by the varying appear-
ance of the latter.
The development of an indifferent Trypanosome has been de-
scribed above (p. 213). When formed, a period of active movement
and multiplication sets in, succeeded later by a resting condition. The
1 The reasons for considering that this parasite is not merely a " fly-parasite "
have been given on p. 201.
THE HA E MO FLA GEL LA TES
parasites now become gregariniform, and strongly recall the similar
phase described by Le"ger (48, 51) in certain Herpetomonads. The
Trypanosome bores into an epithelial cell of the stomach by means
of its flagellum, which is reduced to a short, rod- like organella.
Binary fission may go on, often leading to the formation of a dense
layer of attached parasites. On the parasites again becoming try-
paniform, the flagellar apparatus is reconstituted by the kineto-
nucleus. This alternation of resting and active periods is limited.
Eventually the indifferent Trypanosomes may pass into the blood
-m.k.
E.
F.
FIG. 23.
Development of microgametocyte and male Trypanosomes from an ookinete of male character,
(After Schaudinn.) m.n, male nuclei; f.n, degenerating female nucleus; m.t, male tropho-
nucleus ; m.k, male kinetomicleus ; M.T, male Trypanosome ; r.b, residual body.
of the owl ; or they may apparently become sexual forms, male
or female ; or else, during a period of hunger, they die off.
In the development of an ookinete of male character, or micro-
gametocyte, there is an early separation of the nuclear constituents
into two halves, male and female. The female portion consists of
a large, loose nucleus (Fig. 23, C and D, f.n), which gradually
degenerates and disappears. The male portion, on the other hand,
gives rise to eight little double-nuclei (c and D, m.n), each consisting
of trophic and kinetic portions. The microgametocyte now becomes
rounded, the eight double-nuclei take up a peripheral position (E), and
the cytoplasm opposite each grows out as a little prominence. As-
THE HA k MO FLA GELLA TES
these elongate, each accompanied by a double-nucleus, they take on
a trypaniform appearance, which is completed by the development
of a flagellum. Finally, the eight little male Trypanosomes (F, .v.r),
which are homologous with microgametes, break away from the
central residuum. These forms are apparently incapable of further
development in any way and soon die off. Schaudinn accounts for
this by the condition of the trophonucleus, which, he says, has
undergone reduction.
The early stages in the formation of a female Trypanosome are
similar to those in the case of a microgametocyte. Here, however,
it is the eight small double-
nuclei, representing the
male constituents, which
degenerate, leaving the
large female nucleus to
become differentiated and
give rise to the locomotor
apparatus in the same way
as in an indifferent form
(Fig. 24, c). In the
females the flagellum, etc.,
is poorly developed, and
the movements of the para-
sites are slow and feeble.
These Trypanosomes seem
unable to divide. They
grow to a large size, and
store up a considerable
amount of reserve -nutri-
ment in the cytoplasm.
These forms are the most
resistant to external in-
fluences, and can survive
long hunger-periods, in a gregariniform, resting condition.1 With
the advent of fresh blood into the stomach of the gnat, the female
forms undergo a process of parthenogenesis, consisting of nuclear
reduction and a kind of self-fertilisation. Thus rejuvenated, they
are able to give rise to a fresh succession of Trypanosomes of all
three types.
The Behaviour and Development of the Trypanosomes in the Blood of
tJie Owl. — All the Trypanosomes met with in the bird can be recog-
nised as belonging to one of the three categories observed in the
gnat. On entering the blood, the small indifferent forms at once
1 According to Schaudinn, these gregariniform females can bring about hereditary
infection, remaining dormant in the ovaries until the eggs are laid and the larvae
develop.
Development of a female Trypanosome from an
ookinete of female character. (After Schaudinn.)
m.n, degenerating male nuclei ; a.sp, tirst axial spindle
of female nucleus; f.t, female trophonucleus; /./,-,
female kinetonucleus.
236
THE HAEMOFLA GELLA TES
attach themselves to the red blood -corpuscles (Fig. 25, A and B),
and begin a period of rest and growth. The locomotor apparatus
disappears and the two nuclei come close together. The form of
the parasite is now quite that of a young Halteridium, a well-known
malarial parasite of birds, and, moreover, in twenty-four hours the
first pigment-grains appear in the cytoplasm (c). By this time the
parasite has greatly increased in size. It becomes vermiform and
active, reconstitutes its flagellum, etc., and leaves the host-cell (D),
usually in the night-time, becoming once more a typical Trypano-
morpha (E). This alternation of attachment and growtli with active
movement in the plasma is repeated for six days, until the full size
of the parasite is attained (F and G). The adult Trypanosome then
undergoes successive longitudinal divisions, until the resulting
daughter -individuals have reached a minimum size, when they
repeat the whole cycle. It is worth noting that Schaudirm never
P--
FIG. 25.
Stages in the growth of an indifferent Trypanosome in the blood of the owl. n, nucleus
of red blood-corpuscle ; p, young ectocorpuscular parasite. (After Schaudinn.)
observed any multiplication of the parasites in the gregariniform
(Halteridium) condition, by schizogony, such as is met with in other
Haemosporidia.
Microgametocytes (male forms) arise from very young indifferent
Trypanosomes. Each gives rise to eight small, slender micro-
gametes, in the same way as do the corresponding forms in the
gnat. The microgametes are very specialised organisms. The
trophonucleus (in a reduced condition) forms a long thread, on
which four chromosomes are strung at intervals. There is no free
flagellum at the anterior end, but the body has a whip -like tail
posteriorly.
The full-grown megagametocytes are large female Trypano-
somes, which are no longer able to assume the trypaniform con-
dition, but remain enclosed by the pallid and disorganised host-cell
which they were last able to penetrate. In other words, they are
identical with the female gametocytes of Halteridium. Maturation
THE HA EMOFLA GELLA TES
237
and fertilisation do not take place until the sexual forms are trans-
ferred to the gnat. The process in its main outlines has been
previously described by MacCallum in another species of Halteridium.1
Schaudinn adds that, as soon as the parasites leave the warm-
blooded host, the megagametocytes become rounded off, rupture the
delicate envelope still surrounding them, and then undergo a series
of reduction-divisions, after which they are ready to be fertilised.
The zygote develops into one of the three kinds of ookinete with
Avhich this description began.
Leucocytozoon (" Trypanosoma ") ziemanni. — Even more surprising
are the data put forward by Schaudinn in the case of the other para-
site (or set of parasites) upon which he worked. Just as a species
of Halteridium is regarded as ontogenetically related to Trypanomorpha
noctuae, so Leucocytozoon ziemanni, a parasite of the white corpuscles
and erythroblasts, is said to be intimately connected with what has
been hitherto taken for a species of the genus Spirochaeta, a well-
known bacterial type. Far from being, however, a true member of
the Bacteria, this species at any rate was regarded by Schaudinn
as possessing all the fundamental
characteristics of a Trypanosome
(see Fig. 7, H).
The plan of the life-cycle is
fundamentally similar to that
just summarised, the same sets
of forms being described. Two
or three distinguishing features
may be noticed. The indifferent
Trypanosomes are extremely
spirochaetiform (Fig. 26, A-D) ;
after longitudinal fission, the
two daughter-individuals remain
attached end-to-end (B and c),
the resemblance to a Spirochaete
being thereby accentuated.2 The
resting-phases, little pear-shaped
forms with two nuclear elements
(E and F), are Very PiwplaSma- zieimnni;'E, F, resting - phases of "same; O",
_'• . * ,, , agglomerated cluster of very minute forms.
like and strongly recall the (After Schaudinn.)
Leishman-Donovan bodies. On
the other hand, the gametocytes (in the blood of the owl) are
very large and broad, and distinctly trypaniform, even possessing
1 See the account of the Sporozoa, by Minchin, in this treatise (Vol. I. Part II. ).
3 According to Novy, M'Neal and Torrey (64), Ttipfer has recently cultivated a,
true Spirochaete (i.e. a Bacterium) from the owl, which possesses also minute resting-
forms. Hence Schaudhm's spirochaetiform " Trypanosoma " may have been really
this same Spirochaeta.
form
FIG. 20.
; formation and fission of spirochaeti-
couples " in " Trypanosoma " (Spirochaeta)
THE HAEMOFLAGELLATES
well-marked myonemes. Prior to gamete-formation, both gametocytes
come into relation with the leucocytes, in an unusual manner (see
under " Habitat," p. 205), and lose all trace of locomotor organellae.
Microgamete - formation, maturation
and fertilisation of the megagamete
(Fig. 27), in the gnat, present nothing
unusual. Instead of an ookinete
giving rise to a single Trypanosome,
as in Trypanomorpha, it grows con-
siderably, forming a large coil, and
nuclear multiplication goes On actively
at the same time (Fig. 28). Ulti-
mately, an enormous number of little
spirochaetiform parasites are pro-
duced, which populate the alimentary
tVip crnnl-
l6 §nat>
^f *V>^ , r.v.l^'k'l^ ^,V
of this remarkable work
FIG. 27.
Fertilisation of a megagamete by a
microgamete. The trophic and kinetic
female pronuclei are seen on the left.
Near the middle lie the two reduction-
nuclei. The remains of the host -ceil js based mainly upon the realisation
together with the cast-off envelope of . f i
(After that, in SUcll a Complicated Study,
,, /. ••,-,
there was a grave source of possible
error, and there is nothing to show that this was eliminated.
The opinion has been very generally expressed that Schaudinn
did not sufficiently guard against the liability of confusing and
mixing up the life -histories of entirely distinct parasites. In
the parasite are on the right.
Schaudinn.)
c.
FIG. 28.
Growth and metamorphosis of an indifferent ookinete ; in C nuclear multiplication is well
advanced. (After Schaudinn.)
the first place, it is said that in the species of owl used at least
four separate Haematozoa occurred : two free parasites, namely,
a Trypanosome and a Spirochaete (" Trypanosoma " ziemanni) •
and two intracellular ones, a Halteridium and a Leucocytozoon. It
may be at once admitted that this is quite possible. At any rate,
the entire subject is reopened and cannot be settled definitely until
THE HA EM OF LA GELLA TES
the life-cycle of some or of all the parasites concerned has been
reinvestigated. (See Note below.)
While preserving an open mind upon the matter, the writer
would point out that, if no indubitable confirmation of Schaudinn's
far-reaching conclusions can be said to have been furnished, the
merely negative evidence adduced by Novy and his colleagues is
by no means sufficient proof of their erroneousness. Because the
injection of cultures of certain Trypanosomes in artificial media, into
birds, was not followed by the appearance of Cytozoa in the blood,
these workers apparently conclude (I.e.) that there is no connection
whatever between these two groups of Haematozoa. And this com-
prehensive generalisation is put forward, although in nearly all cases
they failed to obtain even a Trypanosome-infection by this means,
apart altogether from the question whether the particular form with
which they did once succeed had itself an intracellular phase !
We will admit that the cultivation-method, which is of undoubted
use in other ways, may not be without value in studying the life-
history. In certain cases, for example, the behaviour of the parasites
on their arrival in the culture-medium may to some extent indicate
or suggest what happens when they pass into the Invertebrate
host, because of the general similarity of the physical conditions,
etc., to which they are at first subjected. An illustration of this
is afforded by the development of the Flagellate phases of the
Leishman-Donovan bodies in cultures. Nevertheless, we certainly
think that the value (in this respect) of the cultural method of re-
search is limited, and that great caution is necessary in drawing infer-
ences as to a parasite's life-history from the results obtained by it.
We dissent entirely from the American authors when they maintain
that the culture-medium is, for all practical purposes, the equivalent
Note. — The present \vriter has always been reluctant to think
Schaudinn made such a series of mistakes. It has always seemed to him
that this author's celebrated work on the Coccidia of Lithobius has not
been taken into account sufficiently by those who have maintained that
he was hopelessly wrong in the case of the parasites of the Little Owl.
It is with the greatest pleasure, therefore, that on the point of
publication of this article, the writer is able to add that after a most
arduous investigation on the Haematozoa of the common chaffinch
(Fringillu coelebs), he has at length obtained the first definite and
iinmistakable evidence, of which he is aware, in favour of one of
Schaudinn's conclusions. Here, there is only room to .«ay that, as a
result of his observations, he has now little doubt that a Halteridium
parasitic in the chaffinch becomes actually, in certain phases, a little
Trypanosome ; in other words, that the Halteridium and the Try-
panosome which occur in this bird are ontogenetically connected (vide
Q.J. Micr. Sci. liii. p. 339, Feb. 1909). Hence the writer feels reassured
with regard to the truth of the corresponding part of Schaudinn'a work.
240 THE HAEMOFLAGELLATES
of the medium in the Insectan host ; on the contrary, we consider
that the former, whatever indications it may furnish, cannot replace
altogether the latter.
It seems to us that Novy and M'Neal entirely fail to appreciate
the intimate and specific relations of Protozoan parasites to their
hosts, and the remarkable degree to which their biology is adapted
to the same. The Sporozoa in their entirety illustrate this, so do
other parasitic Protozoa, and there is no reason to suppose the Haemo-
flagellates are different. We agree fully with Brumpt that the
chemical and physiological medium of a particular Invertebrate is
essential for the adequate development of all such phases of the
life-history of a Trypanosome as may be undergone outside the
Vertebrate host. And the various researches above summarised,
which go to show that there are right and wrong hosts for the
parasites, and that only certain " ripe " phases, the outcome of the
sojourn in the right host, can reinfect the Vertebrate host success-
fully, afford strong support to this view.
Another criticism put forward by Novy and M'Neal and others
is that the Flagellate phases found in the mosquitoes (Culex), Avhich
Schaudinn regarded as belonging to Trypanomorpha of the Little
Owl, were in all likelihood purely Insectan parasites, of a Herpeto-
monad or Crithidial type, which had nothing to do with the blood
forms. Before discussing this view it is necessary to consider
briefly the subject of these Insectan Flagellates, one which is also of
very great importance because of its bearing upon the phylogeny
and derivation of the Trypanosomes.
7. THE INSECTAN FLAGELLATES : THE EVOLUTION AND
PHYLOGENY OF TRYPANOSOMES.
(a) The Insectan Flagellates.
Several of the earlier workers have commented upon the occur-
rence of Flagellates in mosquitoes. Thus in 1898 Ross observed
parasites which he has recently (74) compared with Leger's genus
Crithidia in Anopheles, larva, pupa, and imago. A similar parasite
was found by Christophers in 1901, occurring in swarms in
Anopheles and Culex. Durham, again, the }rear before, had
noticed numerous " Trypanosomes " in a Stegomyia which had fed
upon a bat. The first serious contributions, however, to our know-
ledge of the Flagellates parasitic in Insects are Leger's researches
(47, 48, 51, 52), 1902-1904, on certain Herpetomonadine forms.
Besides the genus Herpetomonas, Le"ger has distinguished
another type of form, which he has termed Crithidia. Both types
show, in general, an alternation of monadine (flagellate) phases
with gregariniform (resting, non- flagellate) ones. In the latter
condition, the parasites occur as small, rounded, pear-shaped, or
THE HAEMO FLAGELLATES
241
even oblong bodies, attached, often in great numbers, to the
epithelial cells. The flagellum is either absent or reduced to a
short rostrum, serving for attachment (Fig. 29, D and G). The
t\vo nuclei (tropho- and kinetonueleus) lie close together, usually
near the base of the cell. In this phase, the general resemblance
to the Leishman-Donovan bodies may be quite marked. The
distinction between the two generic types is based upon the form
and size of the monadine phase. In Herpetomonas the body is very
elongated . and slender, often acicular, the posterior end usually
FIG. 29.
A, C, Herpetomonas (Crithidia) minuta ; D, attached (gregariniform) phases of same; B, H.
gracilis, Leger ; E. F, //. subulata, Leger ; G, attached phases of same. (After Leger.) x 1800.
tapering away finely (Fig. 29, B and E). In Crilhidia, on the other
hand, it is much shorter and wider, of a pyriform shape ; the hinder
end is never drawn out, but terminates bluntly in a rounded or an
obtuse manner. The parasite Herpetomonas (Crithidia) minuta, L6ger,
appears to be intermediate, however, between these two types, some
individuals approximating to a Herpetomonad form (A), others to a
Crithidial one (Fig. 29, c). As a matter of fact, the classificatory
distinctions between these various Insectan Flagellates cannot be
regarded as at all settled.
In many forms of Herpetomonas (e.g. H. muscae-domesticae,1 H.
jaculum, or H. gracilis (B)), the kinetonucleus is situated near the
1 //. muscae-domesticae is included here as a typical uiiiflagellate Herpetomonad.
Prowazek (69) described this form as possessing a pair of flagella, parallel to and
connected with one another ; he considered this parasite to be a bipolar type (on the
lines of Schaudhm's " Urhaemoflagellate") in which the body has been bent up so
that the two ends have come together and united, the flagella alone remaining
distinct. Leger observed no signs of two flagella in non-dividing individuals, either
of this species or others ; and the same is true of the describers of the numerous
other Herpetomonads.
16
242 THE HAEMOFLAGELLATES
anterior end ; the flagellum is not attached to the side of the body at
all but straightway becomes free, and there is no sign of an undulat-
ing membrane. These forms are mostly parasitic in Invertebrates
which do not suck blood. In H. subulata, however, which is parasitic
in the digestive-tube of Tabanus and Haematopota, predatory on cattle
and horses, the kinetonucleus lies much farther from the anterior
end, and may be almost opposite the trophonucleus (Fig. 29, F).
The flagellum, which has been, as it were, drawn back with it, is in
most individuals attached for the proximal part of its length to the
anterior part of the booty, by means of a delicate cytoplasmic
border, which constitutes a rudimentary undulating membrane.
Thus there is an approach to a trypaniform condition. Again, in
the case of Crithidia fasciculata, found in the intestine of mosquitoes,
Leger has described a very distinct undulating membrane, which
gives the parasite, especially in the more elongated individuals, a
very Trypanosome-like appearance. Novy and his colleagues have
also studied C. fasciculata, as found in Culex • but while admitting
the presence of a membrane, regard it as imperfect and only
poorly developed. These authors describe, in addition, another
Herpetomonadine type, H. (Trypanosoma) culicis, the long forms of
which show clearly an undulating membrane.
We are now in a position to discuss the relation (if any) of
these Flagellates to the Trypanosomes of Vertebrates. When
first describing Crithidia, Leger expressed the opinion that this
parasite was very likely only a stage in the development of a
Haemoflagellate ; further, in his notes on H. subulata (52) he
added the remark that the same was probably true of many of these
Herpetomonad or Crithidial forms found in biting Insects, though
this would not apply, of course, to those species occurring in non-
biting Insects (such as Musca, Sarcophaga, etc.). Moreover, Schaudinn
himself (I.e.) comments on the great similarity between (what he
took to be) the phases of Trypanomorpha noctuae in Culex and those of
Le"ger's Crithidia.
Quite the opposite view is held by Novy and M'Neal, who,
after first (62) regarding the Flagellates found by Schaudinn in
mosquitoes as being simply "cultural" forms, of no real significance
in the life-history, in their later paper (63) consider it much more
likely that the Insectan parasites are entirely distinct from the
Trypanosomes in the blood. (They look upon the parasites found
in leeches, however, as "cultural" forms of Piscine Trypanosomes.)
A similar opinion is expressed by Ross, who points out that he
found Crithidia in the mosquitoes (larvae and pupae) before they
fed on blood, and thinks the parasites were in the first place
swallowed by the larvae.
In a very interesting note Patton has recently (65) described
THE HAEMOFLAGELLATES 243
stages in a Herpetomonas of Culex pipiens, whose life-cycle would
seem in some respects to conform to the scheme suggested by Ross.
In its monadine, determinative form, the parasite appears to be a
typical Herpetomonas, with no indications of an undulating membrane.
All the phases observed, Patton states, exhibit great similarity with
those of Piroplasma donovani (see pp. 256 et seq.). Here it may be
pointed out that in the larvae the parasites resembled the Leishman-
Donovan bodies as they occur in human tissues ; in the nymphs,
stages corresponding to the developmental forms of the Leishman-
Douovan bodies (in cultures, or in the bed-bug), i.e. pear-shaped forms
with flagella, were numerous ; while in adult mosquitoes (mid- and
hind-gut) there were fully developed Herpetomonad forms. Patton
thinks these are passed out into the water, and in some guise or other
ingested by the larvae, the cycle thus beginning again. (He has
privately informed the writer that the parasites may encyst in the
rectum, and be thus passed out to the exterior, to give rise to the
small round forms in the larva.) Patton also notes the occurrence
of a Herpetomonad, which has an obvious undulating membrane,
and which possesses similar rounded aflagellar forms, in a water-
bug. The author concludes by regarding these two parasites as
limited to their Insectan hosts.
In endeavouring to draw some general conclusions from the
above opposing ideas, we are, it seems to the writer, greatly helped
by comparing what is known in the case of other groups of Trypano-
somes. In the first place, as regards those met with in Tsetse-flies,
some of which, at any rate, were formerly considered to be solely
fly-parasites, there appears to be no escape from the conclusion that,
on the contrary, all the forms are blood-parasites. In our opinion
the utmost weight is to be attached to this conclusion. In addition,
we have the Trypanosomes of leeches, which are generally agreed to
belong to different Piscine forms. On these grounds alone, then, it
appears justifiable to suppose that Avian -Trypanosomes are to be
found in mosquitoes, and not at all improbable that some at least
of the phases so clearly described by Schaudinn from mosquitoes
which had fed on infected owls, did indeed appertain to Trypano-
morpha noduae.
Again, to consider the subject from the Insectan standpoint, so
far as the writer can see, Novy and his colleagues have by no
means proved that their Flagellates in wild mosquitoes are not, in
some cases at any rate, phases of Trypanosomes of birds (or other
Vertebrates). For instance, the Trypaiwsoma (Herpetomonas) culicis
described by these authors — with various forms of which they
compare certain phases of Trypanomorplia — is quite as probably a
blood-parasite as a purely Insectan form ; indeed, the possibility of
this being so is admitted by its describers. Moreover, they remark
on the resemblance between the genera Herpetomonas, Crithidia, and
244 THE HAEMOFLAGELLATES
Trypanosoma, especially when the "cultural" forms of the last-named
are compared with those of the other two (or with what Novy and
M'Neal regard as their equivalents — the Insectan forms). In the
case of the Trypanosomes, there is the same relative position of the
two nuclei, either close together, or the kinetonucleus even on the
flagellar side of the trophonucleus ; while certain of them show no
sign of an undulating membrane, but have a typically Herpetomonad
facies. Novy and M'Neal, in fact, would include all these types in
the genus Trypanosoma.
Further, we may point out that according to the view which
these authors themselves hold regarding the origin of the blood-
Try pan osomes, it is most natural to suppose that they are to be
met with, quite at home, in an Insectan host. The American
workers say that parasitism in the living blood is to be looked upon
as the result of previous adaptation to the more or less digested
blood (in the Invertebrate). (As will be seen later, we agree with
this view, where certain Insects are the Invertebrate hosts.) Now,
in this course of evolution of certain blood-Trypanosomes, it may
be reasonably inferred that at one stage the parasites still remain
connected with the Invertebrate after having gained a footing in the
Vertebrate (say a bird). The question would seem to be, rather,
which if any blood-forms so descended have lost the ability to live
(and develop) in their Invertebrate host — a course which would
probably greatly restrict their opportunities for dispersal. (In this
connection the case of the Leishman-Donovan bodies is most
instructive ; cf. pp. 258, 259.)
Hence, summing up, there can be little doubt that certain of
these parasites of mosquitoes, especially those with trypaniform
characters, are connected with some Vertebrate host, just as are
those of other blood-sucking Invertebrates. At the same time, it is
also probable that some of the (typical) Herpetomonads found (e.g.
those occurring in larvae, such as Patton's form, also certain forms,
described by the Sergents) are simply and primarily parasites of
the Insect. Lastly, it is, of course, possible that such a parasite
may have developed a trypaniform condition as an adaptation to
the food of a sanguivorous Insect, without, however, having become
able to live in the Vertebrate host ; but so far no example of such
a case is definitely known. And this brings us to the subject of
the derivation of the Trypanosomes.
(b) Evolution and Phytogeny.
It must be fully recognised that any views which can be at
present advanced upon this interesting, but very puzzling topic are
at best little more than speculations. Formerly (I.e.), the writer
inclined to the idea that all Haemoflagellates are to be derived from
THE HAEMOFLAGELLATES 245
forms originally parasitic in Invertebrates ; in other words, the
Invertebrate was regarded as the primary host, the Vertebrate as
the secondary or intermediate one. We now think this view was
probably, to a considerable extent, wrong ; in this we have been
mainly influenced, on the one hand, by the intestinal Trypanoplas-
mata, and on the other, by the case of T. grayi. As above remarked,
it seems evident that a Vertebrate is the primary host of this latter
parasite ; and the same would follow, by inference, for the other
(Mammalian) Trypanosomes transmitted by Tsetse-flies. Moreover,
the writer thinks he did not allow sufficient weight to the fact
that the Invertebrates which harbour Trypanosomes are, with but
few exceptions, blood-suckers. For these reasons we are now inclined
to consider most of the Invertebrates concerned (e.g. leeches, many
biting-flies, etc.) as the secondary, intermediate hosts of various
Vertebrate parasites (probably all the Piscine and Amphibian ones,
many, but perhaps not all the Mammalian ones, and perhaps some
Avian ones).
The only important 1 exceptions are among Insects ; and here
it is quite likely that we have both primary and secondary hosts.
Besides the Tsetses, Tabanids, etc., the common house-fly and
related genera, in which Herpetomonads (e.g. H. muscae-domesticae,
H. sarcophagae, etc.) occur, ought apparently also to be placed in
the category of secondary hosts. For Prowazek (I.e.) states
that, according to Brauer, the latter flies are probably de-
scended from blood-sucking ones; in Avhich case their parasites
may very well be descended from haemal forms, which are now,
perforce, restricted to the Invertebrate host. On the other hand,
there are several instances of the parasites occurring either in non-
sanguivorous Insects or in forms that only rarely suck blood,
which are, we think, more likely cases of primary parasitism.
Among these, for example, are H. bombycis, in Bombyx mori ; H.
gracilis, in larvae of Tanypus ; Crithidia campanulata, in larvae of
CMronomus plumosus. Lastly, we have the mosquitoes and their
parasites, both of imago and larva. The latter is, of course,
aquatic, and the imago is by no means limited to blood for nutri-
ment. Having regard also to the illustrative series of transitional
forms between the monadine type and the trypaniform one, made
known by Leger and others, it appears to us that here as well the
Insect is the primary host of the various Flagellates concerned, and
that where these are connected with a Vertebrate host the latter is
to be regarded as the secondary, intermediate one. This would
apply chiefly to certain parasites (e.g. Trypanomorpha) of birds,
though not necessarily, it is to be noted, to all.
Many authorities (such as Laveran and Mesnil, Liihe, Novy and
1 Herpetomonas biitschlii from a Nematode (Trilobus) and the curious Trypano-
phis from Siphonophores do not appear to have any bearing upon this question.
246 THE HAEMO FLAGELLATES
M'Neal) have maintained the view that the Invertebrate is the
primary host in all cases. Minchin, however, has always considered
the Vertebrate as the principal host ; and in his latest memoir
on the Trypanosomes of Tsetse-flies (58), proofs of which he very
kindly allowed the writer to see, he regards all Trypanosomes as
descended from an intestinal Vertebrate form, and indicates the
lines upon which the evolution may be supposed to have advanced.
This ancestral form produced resistant cysts for dispersal, and thus
contaminative infection was brought about. (It would be extremely
interesting to ascertain whether the intestinal Trypanoplasmata
known (see p. 249) have such a cyst-formation.) The next stage in
evolution is when the parasite has penetrated the intestinal wall,
and come into relation with the circulatory system. Until it came
into relation with a blood-sucking Insect, this type would have to
pass back into the alimentary canal for dissemination. So far, we
have no evidence of an existing instance of this stage. Subsequently,
the blood-parasite became adapted to an Insectan host, in the gut
of which it encysted, reinfection of the Vertebrate being by the
contaminative method. T. grayi in all probability furnishes an
example of this type. Lastly, the parasite is thoroughly adapted
to the biology of the Insect and passes forwards to the front part
of the alimentary canal : infection of the Vertebrate is now by the
inoculative method. This may possibly be combined in some cases
with the contaminative mode, but probably in most encystment no
longer takes place, being unnecessary (e.g. the lethal Trypanosomes,
Piscine forms, etc.).
Of course, in those cases where, as above remarked, the Verte-
brate is probably the secondary host, there is no reason to suppose
that, as a rule, the parasites leave the circulatory system.
Phylogeny. — As stated at the beginning of this article, the
Trypanosomes, as a whole, are to be regarded as including two
entirely distinct families, in one of which (the Monadine type) the
attached flagellum becomes free at the true anterior end, and in the
other (the Heteromastigine type) at the true posterior end. The
former type is derived by the progressive migration backwards of the
kinetonucleus towards the posterior (aflagellar) end, in the manner
well illustrated by Leger's series of Herpetomonadine forms (see
Fig. 29). The latter type is derivable from a Trypanoplasmatine
ancestor — itself in turn doubtless to be derived from a fiodo-like
form — by the loss of the anterior free flagellum ; l so that the non-
flagellate extremity is the true anterior one.
The writer is unable, owing to limits of space, to enter fully
1 A comparison of the different degree of development of the flagella in various
forms is instructive as illustrating the manner in which the Trypauoplasmatine condi-
tion may have resulted from that found in Bodo, and its further evolution.
THE HAEMOFLAGELLATES 247
here into the reasons for and against this diphyletic view, which
was first put forward by Le"ger (49). A complete discussion will
be found in his Review of the Haemoflagellates (pp. 270-278).
Liihe, in his account of the Haematozoa in Mense's Handbuch der
Tropenkrankheiten (2), has adopted it, though on somewhat different
lines from those taken by us. Minchin, also, has expressed the
opinion (Brit. Mai. Journ., 1907, ii. p. 1320) that - Trypanosomes
are most likely diphyletic. On the other hand, many authorities,
including Laveran and Mesnil, hold the view that all Trypanosomes
are descended from Herpetouionadine ancestors, basing their opinion
on the resemblance to a Herpetomonad shown by many Trypano-
somes in cultures, and by young individuals of T. leivisi (cf. Fig. 20).
In many cases, at any rate, we regard this phase — as we have
previously said — rather as a " pseudo-Herpetomonadine " condition ;
and in such cases do not attribute to it the phylogenetic importance
which is done by some, but consider it to be probably capable of
explanation on other grounds (see I.e.}. A fact which seems to us
of considerable significance is that Trypanoplasmatine forms are
known to occur in the digestive tract of fishes, e.g. " Trypanoplasma "
intestinalis in Box boops, and " T." rentriculi in Cydopterus lumpus;
moreover, another Heteromastigine parasite (Bodo lacerfae) is found
in a lizard. On the other hand, no indubitable Herpetomonad has
yet been described from the alimentary canal of a Vertebrate, which
we may assume to have been the original habitat of the primitively
Vertebrate parasites.
Hence, all things considered, we come to the general conclusion
that the Trypanosomes which have the Vertebrate for their primary
host are Heteromastigine forms ; those derived from primitively
Invertebrate parasites, on the other hand, are probably Monadinc
forms. Endeavouring to use this view practically, for purposes of
classification, or, at any rate, of convenient partition of the Trypano-
somes, we have as follows : — The parasites of fishes belong to the
Heteromastigine type ; this can be said with some degree of
confidence, in spite of the " Crithidial " forms assumed by the
parasites in leeches. Probably the same is true also of most forms
of cold-blooded Vertebrates. Of the Avian ones, on the contrary,
some at any rate (e.g. those of the type of Trypanomorpha noctuae)
are Herpetomonadine forms. Among Mammalian parasites the
various lethal Trypanosomes (e.g. T. brucii, etc.) are to be regarded
as Heteromastigine forms. We will only mention in passing that
certain movements of these forms in the living blood (cf. p. 217)
suggest very forcibly that the aflagellar end is the true anterior
extremity. Of the other known (accustomed) parasites of Mammals,
whose number has considerably increased of late, it is quite possible
that some (e.g. those of bats, which may have, perhaps, mosquitoes
as their alternate hosts) are Herpetomonadine forms.
248 THE HAEMOFLAGELLATES
8. SYSTEMATIC.
The reasons for the division of the Trypanosomes into two
distinct families have been alluded to in the previous section.
Besides the fundamental diagnostic characters, namely, the true
orientation of the body and the biological features associated there-
with, it is quite likely that important differences in regard to the
life-cycle will become evident as our knowledge increases.
SUB-ORDER MONADINA.
Family TRYPANOMORPHIDAE, Woodcock. — Haemoflagellates
derived from a uniflagellate, Herpetomonadine form, in which the
point of insertion of the flagellum into the body has travelled back-
wards from the anterior end for a considerable distance, the
flagellum itself having become, concurrently, attached to the body
for part of its length by means of an undulating membrane. At
present only one genus is distinguished.
Genus Trypanomorpha, Woodcock. With the characters of the
family. The genus was founded for Schaudinn's Avian parasite,
Trypanosoma (Halteridium) noduae (Celli and San Felice),1 from
Athene noctua and Culex pipiens. As above mentioned, it is probable
that other Avian forms, and perhaps some Mammalian ones, will be
found to agree with this generic type ; at present, however, it is
not possible to say which with any certainty, and hence they are
retained under the heading " Trypanosoma."
Reference has been made to the possibility of Leger's Crithidia
fasciculata from Anopheles maculipennis, and other Insectari parasites
which show marked trypaniform characters, being also really
Haemoflagellates. In such a case the genus Trypanomorpha may
prove to be synonymous with Crithidia ; if so, the latter name will
take priority. Ltihe, it is to be noted, in his account of the
Haematozoa (I.e.), regards all the Trypanosomes of Mammalia as
belonging to the Herpetomonadine type, and has proposed the new
generic name Trypanozoon for these forms.
SUB-ORDER HETEROMASTIGINA.
Family TRYPANOSOMATIDAE, Doflein. — Flagellates, with but
few exceptions haemal parasites, derived from a bi flagellate, Bodo-
like type, in which the posteriorly directed (trailing) flagellum is
always present and attached to the side of the body by an undu-
lating membrane, of which it constitutes the thickened border.
1 Schaudinn placed this form in the genus Trypanosoma. We incline, however,
to the view that the type-species of that genus (T. rotatorium) is a Heteromastigine
type, and therefore restrict that genus to such forms.
THE HAEMOFLAGELLATES
249
The other, the anterior flagellum, may or may not persist. At
least three genera known so far.
Genus Trypanoplasma, Laveran and Mesnil. The anterior
flagellum is present.
Type-species, T. borreli, Lav. and Mesn. (Fig. 11). Length of body
20-22 /*, of free flagella 13-15 /x, breadth 3^-4^ p.. Parasitic in Leuciscus
erythrophthalmus, rudd, and Phoxinus laevis, minnow. Other species are T.
cyprini, from the carp, and T. varium, a rather larger form, from the loach.
Genus Trypanophis, Keysselitz. The anterior flagellum is pre-
sent. The free part of the posterior flagellum is short, and the
undulating membrane is straight and relatively narrow. The
species for which this genus was founded is parasitic in certain
Siphonophores, and almost certainly not a haemal form.
e.C, -
Fit;. 30.
Trypanophis grcitjbeni (Poche). e.c, ectoplasmic cap; e.l, delicate ectoplasmic layer, thin-
ning out posteriorly ; i, inclusions in the cytoplasm ; x, nuclear body of uncertain origin and
significance. (After Keysselitz.)
Type-species, T. yrobbeni (Poche). Average length 60-65 //,, width
about 4 p.. From Cucubalus kochii, Halistemma teryestinum, Monophyes
gracilis, Gulf of Trieste. Apparently the same parasite has also been
observed in Abyla pentagona, Gulf of Naples. The organisms are to be
found in all the ramifications of the coelenteron, from the digestive-cavity
of the gastrozoids to the radial canals of the medusoid buds. Nothing
is known with regard to the transmission from one Siphonophoran colony
to another.
Great interest attaches to certain Trypanoplasmatine parasites
recently described from the alimentary canal of fishes. In their
general morphology and the possession of an undulating membrane
they agree closely with Trypanoplasma, and their describers have
included them in this genus, as T. intestinalis, L6ger, and T. ven-
250
THE HAEMOFLAGELLATES
triculi, Keysselitz. So far as those points are concerned, however,
they agree also with the above-mentioned genus Trypanophis (cf.
Figs. 30 and 31). Indeed, Leger, in his account of T. intestinalis,
commenting on the great resemblance of this
parasite to Trypanophis, suggested that the latter
form might be included in Trypanoplasma. We
consider that Trypanophis grobbeni, on account
of its curious habitat and somewhat peculiar
nature, should certainly be kept distinct. More-
over, as regards the intestinal Trypanoplasma-
tine forms, the fact that they are most likely
not haemal parasites renders it very probable
that their life-cycle differs in many ways from
that of the ~b\ood-Trypanoplasmata (cf. the hypo-
thetical stages in evolution outlined above,
p. 246). Formerly, we placed " T." intestinalis
with Trypanophis on these grounds ; but it seems
preferable to consider it as belonging to an
down the side near the independent genus, along with " T" ventriculL
undulating-membrane (cf.
in B the As we are averse to the practice of instituting
;ti /-irt-1-iV.ift -1- "
FIG. 31.
" Trypanoplasma " in-
testinalis. In A a row of
spherules is seen running
kinetonucleus is double. . . ,
(After an original draw- new genera in a treatise, we do riot propose to
Lege^f^ ^ ^ ^ d° SO here-
Before leaving this point, it may be noted
that, in the case of these Heteromastigine forms, the presence of
an undulating membrane and consequent trypaniform appearance
does not bear the same relation to a haemal habitat as seems to
be the case in the Monadine types. As Doflein has already pointed
out,1 the undulating-membrane, in the Trypanoplasmatine parasites,
has doubtless been developed as the result of the contiguity of the
trailing flagellum of the Bodonine type to the side of the body ;
a quite different origin from that in the other section. Hence this
condition is more or less independent of the habitat of these forms.
Genus Trypanosoma, Gruby (principal synonyms : 2 Undulina,
Lank., 1871 ; Herpetomonas, Kent, 1880, but only in part, since
the type-species is H. muscae-domesticae ; Paramoecioides, Grassi,
1881; Haematomonas, Mitrophan., 1883; Trypanomonas, Danil.,
1885, for young forms). There is no anterior flagellum. The
point of insertion of the attached (posterior) flagellum into the
body, and, consequently, the commencement of the membrane, may
be anywhere in the anterior half of the body, but is usually near
the extremity.3
1 Die Protozoen als Parasiten und Kranklieitserreger (Fischer, Jena, 1901),
p. 54.
2 For remarks on the synonymy of this genus, readers are referred to the writer's
previous article (p. 287).
3 The type-species is T. rotatorium, Mayer, of frogs. At present, unfortunately,
this parasite cannot with certainty be included in the above diagnosis, owing to its
THE HAEMOFLA GELLA TES
251
The sub-classification of this genus, or rather the grouping and
arrangement of the numerous Trypanosomes at present included in
it, is a question of great difficulty and one in regard to which
hardly anything has been done as yet.1 This is chiefly owing to the
fact that so little is still known of the life-history of most that
hitherto any attempt to group the parasites has been dependent upon
their adult morphology. This is not a very satisfactory criterion,
since, as we have seen, on the one hand, the differences in this
respect between different forms may be very slight ; and on the
other, a particular parasite may itself vary very greatly at different
times and under different conditions (see under " Morphology ").
Moreover, it may very well be that as more life-histories come to be
revealed, some of the forms at present placed for convenience in
FIG. 32.
A, Tri/iKuwsoma gamliiense (from the blood), after Bruce and Labarro ; B, T. equinum, after
Lignieres ; C, T. evansi, from an original drawing ; D, T. cquiperdum, after Lign.
the genus Trypanosoma will have to be transferred to new ones
(as an example may be mentioned T. grai/i).
For the present, at any rate, a very useful aid towards dis-
tinguishing different species is furnished by the biological relations
of the parasites. For it may be assumed that here, as is usual
among the Sporozoa, a particular species is, in general, restricted
either to one particular host, or, at most, to a few allied ones.
Difficulty arises in considering the Mammalian forms, many of
which have never been observed in the true, natural hosts, but only
unusual shape, position of kinetonucleus, etc. The occurrence, however, of an
allied form in Hyla, which is evidently intermediate between T. rotatorinm and
the more typical, fusiform species, suggests that the former also belongs to the Hetero-
mastigine section.
1 Koch, however, has attempted a classification of the Mammalian forms, which he
arranges in two groups, the first including such different forms as T. lewisi and the
large T. theileri of cattle ; the other, most of the lethal forms, which he considers
are not distinct species. This arrangement is very artificial and has nothing to
recommend it.
252
THE HAEMOFLAGELLATES
in various unaccustomed animals, for which they are more or less
lethal. The important immunisation experiments first carried out
by Laveran and Mesnil, and since then by other workers, have
shown, however, that several of the parasites causing the different
trypanosomoses now known are distinct species. •
A full description of all the known forms and tlieir characteristics is
impossible within the limits of this article. It must suffice to mention
some of the more important and better-known parasites, arranged under
the different classes of Vetebrate hosts ; for fuller details regarding them,
reference should be made to the writer's previous account, or to Nabarro's
revised edition of Laveran and Mesnil's treatise, which is most useful in
A.
B.
C.
FIG. 33.
A and B, T. theileri; C-E, T. "transwalien*:." x 1250. (After L. and M.)
this connection. A list of known hosts and their Trypanosomes is given
at the end of this chapter.
(a) Parasitic in Mammals. Trypanosoma lewisi, Kent, the common
natural parasite of rats (Figs. 7, A ; 20, A). Length * 24-25 p., breadth
l|-2 p.. This species is characterised by its narrow and pointed aflagellar
extremity, and by the position of the trophonucleus in the flagellar half
or third of the body. The cytoplasm is usually free from granules. T.
Irudi, Plitnmer and Bradford. Length 28-30 p., breadth 2-2| //. The
anterior end is usually bluntly rounded (Figs. 7, B ; 17, A). The cytoplasm
often contains granules in the posterior half. Natural hosts probably
various Antilopidae (e.g. gnu, " koodoo," etc.), and buffaloes. The cause of
Nagana or Tsetse-fly disease in cattle, horses, etc., in South Africa. T.
gambiense, Button (Syn. T. ngandense, Castell). Length 21-23 fj., breadth
1^-2 /JL. This species (Fig. 32, A), according to its average size, is one of
the smallest known. The cause of human trypanosomosis in West and
1 The dimensions given are intended to indicate the average size of the parasite in
each case, but can only be considered as approximate. The length is inclusive of the
flagellum, unless otherwise stated.
THE HAEMOFLAGELLATES
Central Africa. The earlier stages of the disease, when the parasites are
confined to the blood, are known as Trypanosoma-k\er ; the later ones, after
the organisms have penetrated into the cerebro-spinal canal, constitute the
deadly malady of sleeping-sickness. The true, natural host is unknown.
T. equinum, Voges (Syn. T. elmassiani, Lign.). Length 22-25 p, width
1^-2 /j.. Distinguished from all other forms by the minute size of the
kinetonucleus (Fig. 32, B). Hydrochoerus capybara is almost certainly a
natural host. Other well-known lethal parasites are : T. evansi (Steel), of
Surra in horses in Indo-Burmah (Fig. 32, c) ; T. eqiiiperdum, Doflein (Syn.
T. rouyeti, Lav.), the cause of Dourine in horses, transmitted naturally by
coitus (Fig. 32, D) ; T. theileri, Laveran, a very large form, often surpassing
50 p. in length, which causes "bile-sickness" of cattle in the Transvaal
(T. transvaaliense, Lav., with the kinetonucleus near the middle of the
FIG. 34.
T. johnstoni. g, deeply-staining granule at
distal extremity of flagellar border, x 1500.
(After Dutton and Todd.)
Fl°- 35.
A Trypanosome from Sene-
gambian birds, x 150C. (After
D. and T.)
body (Fig. 33, C-E), has been shown to
be, in all probability, only a phase of
T. theileri) ; and T. dimorphon, Dutt.
and Todd, which gives rise to a trypano-
somosis of horses in Senegambia.
(6) Parasitic in birds. T. avium,
Danil., Lav. emend., probably the form
to which Danilewsky's original investi-
gations related, occurring in owls and,
according to Novy and M'Neal, in
various other birds. Length 35-45 />t
(Fig. 7, F). T. johnstoni, Dutt. and
Todd. Length 36-38 //., width 1^- p..
TVn« -nnrnsitp in <5O «lpnrlpr i<5 'iltnnst-
llns parasite is so i as almost
to justify the description spirochaeti-
form (Fig. 34). From Estrelda. The opposite extreme of form is
seen in a Trypanosome, T. hannae, Pittaluga, originally described by
Hanna (25) from an Indian pigeon (Fig. 7, o) ; this is relatively
very broad, and has, moreover, a long, attenuated aflagellar extremity, the
latter character being not unusual in bird-Trypanosomes. On the other
FIG. 30.
T. paddae. At x the base of the flagel-
lum is thickened prior to division.
X 1200. (After Thiroux.)
254
THE HAEMOFLAGELLATES
hand, Button and Todd have described a wide form from Senegambian
birds, which has this end bluntly rounded, giving the parasite a stumpy
appearance (Fig. 35). It is interesting to note that this Trypanosome
occurred in the same birds (Estrelda) in which the very different T.johnstoni
was found. T. paddae (Fig. 36), from the Java sparrow, has been studied
by Thiroux (83), and apparently lends itself to cultivation and inoculation
into other birds as readily as do many Mammalian forms. Finally, there
is the remarkable parasite, " T." (Spirochaeta) ziemanni, described by
Schaudinn. If this form is really a Trypanosome, it certainly belongs
to the Heteromastigine section, and may for the present be placed in the
genus Trypanosoma. But it may be, after all, a true Spirochaete, and
belong to the Bacteria (cf. footnote, p. 237).
(c) Reptilian forms. Scarcely any Trypanosomes have been observed
in Reptiles. The only one which has been figured is T. damoniae, Lav.
and Mesn. Length 32 /A, breadth 4 //,. The general structure (Fig. 7, j)
presents nothing unusual. As in Piscine forms, the body is often rolled
up on itself. From Damonia reevesii, a tortoise. Another form (T. boueti),
lately described from a lizard, is said to resemble the flat, smooth type
of T. rotatorium (below).
(d) Parasitic in Amphibian hosts. The Trypanosomes of frogs show
a remarkable variation in form, size, and appearance, and it is not at all
certain, in some cases, how far this is due to polymorphism, and how far
to distinct species being concerned. The type-species of the genus is T.
rotatorium (Mayer). (Synn. Amoeba rotatoria and Paramoecium costatum
or loricatum, Mayer, July 1843 ; Trypanosoma sanyuinis, Gruby, Nov.
1843 ; Undulina ranarum, Lank.,
1871.) Laveran and Mesnil have
worked on this form and dis-
tinguish two principal types, one
having the surface of the body
thrown into parallel ridges (Figs.
8, B ; 37, A), the other having a
smooth, regular surface (Figs. 8, A ;
37, B). The parasites are very
large, being 40-60 //, in length, by
from 5-40 p. in width ; the two
dimensions vary more or less in-
versely. The great variation in
shape of the body and of the
anterior end is seen from the
figures. The kinetonucleus is
aisually situated some distance from the non-flagellate or anterior extremity,
.and may be quite close to the trophonucleus ; sometimes, however, it is
fairly near the end. Chiefly for this reason, Franca and Athias (22)
split up the species into two, T. costatum or loricatum (Mayer), with the
kinetonucleus near the centre, and T. rotatorium, with it near the end.
As the position of this organella is very variable and intermediate stages
occur, we do not think anything is gained by doing this, at present.
-Similarly, the validity of two new species which Franca and Athias
FIG. 37.
T. rotatorium (Mayer). Bibbed and smooth
forms, x 1000 (approx.). (After L. and M.)
THE HAEMOFLACELLATES
255
create, namely, T. undulans and T. elegans, is somewhat doubtful. Button
and Todd have described two very long forms from Gambian frogs, which
they have named T. mega and T. karyozeukton ; these forms exhibit
peculiarities in the cytoplasm (see p. 212), and in the latter parasite a
chain of chromatic granules runs from one nucleus to the other (Fig. 8, D).
A type which is certainly distinct is T. inopinatum, Sergent, from the
edible frog. This parasite (Fig. 8, c) is slender (25-30 /z by 3 //,), and
resembles a Mammalian or Piscine form. Another well-characterised
species is T. nelspruitense, Lav., in which the body is very vermiform and
the free flagellum very long (Fig. 8, E).
(e) Forms parasitic in fishes. Trypanosomes occur very frequently
in fishes, and a great many species have been described. T. remuki,
Lav. and Mesn. This para-
site occupies about the same
position among Piscine Try-
panosomes as does T. lewisi
among Mammalian ones. It
is a slender form, with taper-
ing, pointed extremities. The
trophonucleus is in the pos-
terior half of the body. Para-
sitic in Esox lucius, the pike.
Laveran and Mesnil have dis-
tinguished two varieties, based
upon the considerable differences in size met with, namely, var. parra,
medium length 30 /x, of free flagellum 10-12 /JL, with breadth 1^-2 p. ; and
var. magna (Fig. 8, L), minimum length 45 /x, of which 17-20 /A is for the
flagellum, and breadth 2-2J //,. T. cobitis and T. carassii (Mitrophanow)
were among the first Piscine forms to be described, and probably corre-
spond to many of those seen by Danilewsky. T. granulosum of the eel
is a remarkably long, eel-like form (Fig. 8, K), 70-80 //. by 2|-3 p. The
kinetonucleus is relatively very large, as is often the case in Piscine forms,
and close to the anterior end, which is sharply acute. Several forms
have been observed in flat-fish, certain of which (e.g. T. flesi, Lebailly)
belong to a different type, being relatively wide, with only a short
flagellum. From Elasmobranchs, two very large forms (T. scyllii and
T. raiae) have been described by Laveran and Mesnil ; these attain a
length of 70-80 yit, and usually have the body coiled up on itself (Fig.
38).
FIG. 38.
A, T. scyllii ; B, T. raiae. x 1200.
(After L. and M.)
APPENDIX.
(A) THE " LEISHMAN-DOXOVAN- WRIGHT " BODIES
Although these remarkable bodies have not been shown yet to
possess an actual trypaniform structure, the fact that they are known
to give rise to Flagellate phases of very Herpetomonadine character
points so conclusively to their connection with that type of parasitic
Flagellate, and is of such importance as proving that a parasitic Flagellate
256 THE HAEMO I-LAGELLATES
can and does become intracellular in the Vertebrate host, that a brief
consideration of them is essential to the completeness of this article.
The Leishman- Donovan bodies are constantly found in certain
tropical fevers (such as Dum-dum fever, Kala-Azar), particularly pre-
valent throughout Indo-Burmah, of which they are now generally admitted
to be the cause. These parasites were discovered by Leishmau in 1900,
but before his first account of them was published (91) they were also seen
independently by Donovan. Moreover, organisms very similar to these
parasites (indeed, morphologically, the two kinds are hardly distinguish-
able) are found in various sores or ulcers (known as Delhi boil, Oriental
sore, " bouton d'Alep "), to which people in different parts of the tropics
are liable. The latter were first clearly recognised and described by
Wright (97).
In the former type of disease, there is a general systemic infection,
the parasites spreading to all parts of the body, and being met with in
the spleen, where they are usually very abundant, liver, bone-marrow,
and (more rarely) in the peripheral circulation. The latter type of
disease, on the other hand, is one of localised infection, the organisms
being restricted to the neighbourhood of the skin lesions ; and in this
case the parasites never seem to become distributed throughout the body,
producing a systemic infection. For this reason, though the organisms
in the two cases seem to be undoubtedly closely related, they are probably
specifically distinct. In the Vertebrate host, the parasites are generally
intracellular. Free forms are met with, doubtless liberated by the break-up
of the host-cells, but these probably soon invade fresh cells. Leish man's
form is parasitic in large uninuclear leucocytes (Fig. 39, II), and especially
in cells of the vascular endothelium, which are often packed with the
little bodies, becoming greatly distended (as macrophages). According to
both Donovan (88) and Laveran and Mesnil (90), the parasites also
occur in the red blood-corpuscles. Wright's form occurs in the ulcer
cells, and in large migratory corpuscles (phagocytes) of the granulation-
tissue.
The parasites themselves are very minute, and usually ovoid or
pyriform in shape, the latter being perhaps the more typical. The
splenic form is somewhat smaller than the localised type, being 3|-4 p,
in length by l|-2 p. in width (39, I), while Wright's form is about 4 fj.
by 3 //, (39, III). The cytoplasm is finely granular and fairly uniform
in character ; but sometimes it is vacuolated. The most interesting
point about the morphology is the fact that two chromatic bodies, of very
unequal size, are invariably to be recognised. The larger nuclear body,
which corresponds to the trophonucleus of an ordinary Haemoflagellate,
is usually round or oval ; the smaller one, representing a kinetonucleus,
has the form either of a little rod or of a round grain, and stains very
deeply. The two nuclei are generally quite separate, but sometimes they
appear to be connected. The organisms multiply in two ways : (a) by
binary fission, and (6) by multiple division or segmentation. The chief
stages in the first method are well known (Fig. 39, I, 6) ; they offer great
resemblance to the corresponding process in Piroplasma. Multiple division
has not yet been so satisfactorily made out. It appears to conform more
THE HAEMOFLAGELLATES
257
or less to the radial or rosette type of multiplication (I, c), enlarged
rounded parasites, with a varying number of nuclei (up to about 10)
uniformly arranged near the periphery, having been often noticed. The
details are, however, rather differently described by different workers.
Our knowledge of any further development undergone by these
parasites is limited at present to the Leishman-Donovan bodies, and is
due in the first instance to Rogers (94). Rogers cultivated the parasites
..
I.
F/o. 39.
I, Leishmania (Piroplasmu) donovani (Lav. and Mesn.). a, typical pear-shaped or oval forms ;
6, various stages in binary fission ; c, nuclear division, preparatory to multiple fission ; d, Rndo-
corpuscular forms in red blood-corpuscles (p, pigment grains) ; e, bacillary form of the parasite
in a corpuscle ; M, large macrophageal cell with many parasites. (After Donovan.) II, Uni-
nuclear leucocyte (L) containing several parasites. (After L. and M.) Ill, L. (P., Helcosama)
troj>i<-<i (Wright), a, single individuals ; b, dividing forms. (From Mesnil, mostly after Wright.)
IV, L. (P.)donocani in cultures of different ages, a, ordinary forms of varying size ; 6, c, stages
in multiple division ; e, /, and g, flagellate forms. (After Rogers.)
in citrated blood, at a lower temperature, and made the astonishing
discovery that Flagellate forms were developed from them. This result
has since been fully corroborated and further details ascertained by Christo-
phers (87), Leishman and Statham (92), and others. Different stages
in the process are seen in Fig. 39, IV, d-g ; and Fig. 40. The parasites
increase greatly in size and become vacuolated (this is probably due to
the artificial medium in which they are). Multiplication by binary fission
takes place, and with successive generations the shape of the body alters ;
from being pyriform it passes through a fusiform condition, and finally
becomes elongated and slender. Meanwhile, in many of these phases, a
17
258
THE HAEMOFLAGELLATES
flagellum has made its appearance ; when this is fully developed the
parasite quite resembles an ordinary Herpetomonas.
The origin of the flagellum is interesting. A distinctive vacuole-like
structure arises near the end which will become the flagellar end, in close
connection with the kinetonucleus — a point, probably, of importance.
This vacuole increases and suddenly is ruptured, some of its contents
being extruded to the exterior as a tuft or fringe of pink -staining
substance. In the middle of this, a small flagellum is seen, but how
exactly it is formed is not known. Once constituted, the flagellum grows
rapidly. Even in the most fully-developed Flagellate phases, however,
in no case has anything comparable to an undulating-membrane been
observed. The kinetonucleus is comparatively near one end of the body,
VV.Bi-.
FIG. 40.
Stages in the development of the flagellated form. (From Leishman.) 1, ordinary spleen
parasite ; 2, 3, growth and vaeuolisation in cultivation ; 4, 5, appearance and growth of the
special " flagellar vacuole," close to the kinetonucleus ; 6, rupture of this vacuole and protrusion
of a tuft of pink-staining threads ; 7, growth of the flagellum, its base being inserted in the
collapsed vacuole ; 8, acquirement of the Herpetomonad form.
and the flagellum springs directly from that end, not being actually
connected, apparently, with the former organella.
Another remarkable process observed in these developmental forms in
cultures is unequal longitudinal fission. Very thin, sickle-like (" spirillar ")
portions of the body are split off from one side of a parent-individual.
More than one of these thread-like forms may be successively cut off. The
unusual feature of the process is that neither the two principal nuclear
elements nor the flagellum take part in it. Subsequently, these fission
forms seem to give rise to very slender flagellar ones. To what extent
this represents a normal (natural) mode of multiplication is uncertain.
No other stages have been observed in cultures, and the organisms
degenerate and ultimately die off. The above facts demonstrated, how-
ever, that the Leishman-Donovan bodies can undergo important changes
outside the human host, and rendered it probable that they do so
naturally, though whether in the free condition or in an alternate host
was, until lately, quite unknown. The superficial position of the localised
form (Wright's type) points very strongly to infection by means of some
biting Insect, and it is natural to infer that the same holds also for the
THE HAEMOFLAGELLATES 259
splenic type, when its occurrence in the circulation is borne in mind.
Here, again, Kogers gave the lead. This worker, finding that the parasites
developed flagellar stages most readily in an acid medium, suggested (95)
that the stomach of some blood-sucking Insect (such as a flea or bug) was
probably the place where the above described extra-corporeal phases of
the parasite's existence would be found to occur. This has been recently
proved to be the case by Patton (93), who has found the Flagellate phases
in the bed-bug (Oimex rotundatus [macrocephalus]). It is most probable,
therefore, that the infection of human beings is brought about by this
Insect, which serves as an alternate host.
The systematic position and affinities of this parasite have been much
discussed. Leishman at first considered the organisms as representing
involution-forms of Trypanosomes, being largely influenced by the two
chromatin masses ; in this view he was supported by Marchand and
Ledingham. Later, he went farther and suggested that they perhaps
represented an actual stage in a Trypanosome life -cycle. Laveran and
Mesnil, taking more into account the general form and very suggestive
binary fission, thought a new species of Piroplasma was concerned, and
named the bodies Piroplasma donovani ; in this view Donovan and others
have concurred. Other authorities (e.g. Christophers, Ross, and Wright)
thought they saw in the parasite an entirely different kind of Sporozoan.
Ross called the splenic type Leishmania, and a little later, Wright termed
the ulcer- form Helcosoma tropicum. Recently, Rogers has placed the
Leishman-Donovan form in the genus Herpetomonas, on account of the
similarity in the Flagellate- phase.
It is probably best to regard the parasites as generically new forms ;
in this case the splenic form becomes Leishmania donovani and the ulcer-
type, which is most likely a separate species, L. tropica. The organisms
are closely related, on the one hand, with the Herpetomouads, and on
the other with the Piroplasmata. With regard to the parasites possessing,
at some period or other, a trypaniform structure, the complete absence of
an undulating-membrane in the cultural forms is no proof that one is not
present under certain conditions in Nature. For, as already noted, many
Trypanosomes, when " cultivated," may have a very slight indication of
a membrane or none at all. Nevertheless, it is by no means improbable
that these parasites have remained solely Herpetomonad forms and have
not developed the characteristics of a Trypanosome. The fact that the
Flagellate-phase is only known to occur in the Invertebrate host, points
very strongly to this being the original primary host. In this connection
the Herpetomonas lately described by Patton from Culex pipiens (to which
reference has been made above) is very interesting, because of the occur-
rence of resting- phases resembling the Leishman bodies. Leishmania
may well be a similar form which, parasitic in a sanguivorous Insect,
has become adapted to the Vertebrate host in its resting, gregariniform
phase, and perhaps never develops a trypaniform condition, or even an
active flagellar phase therein. Turning to the other side, there can be
little doubt that the Piroplasmata are intimately connected with the
Leishman-Donovan- Wright bodies. The general agreement of the intra-
cellular forms as regards appearance and binary fission has been noted
260 THE HAEMOFLAGELLATES
above. In addition, there is the most important point that some species
of Piroplasma are stated to show, at certain times, the same characteristic
nuclear dimorphism. Schaudinn was the first to notice this, in the case of
P. canis ; and he was confirmed by Kossel and Weber. Since then additional
observations to the same effect are recorded by other workers (e.g. Liihe)
for various species. This being so, the Piroplasmata also are most
probably to be derived from Flagellate forms.1
(B) A word or two, lastly, with reference to the supposed connection
of the Spirochaetae with the Trypanosornes. Besides the instance of
Trypanosoma (Spirochaeta) ziemanni, Schaudinn, in his great memoir (I.e.),
was inclined to consider that other Spirochaetae (e.g. S. obermeieri of
relapsing fever) were also only phases in the lii'e-cycle of other Haemo-
flagellates. Subsequently, however, as a consequence of his investigations
on Spirochaeta plicatilis, the type-species, and other forms, he relinquished
this view, finding that the latter were of a totally different nature, and
should rather be placed with the Bacteria. Much has since been written
with regard to the nature and affinities of the various Spirochaetae. We
do not propose to go into the general question here, as the preponderance
of opinion is decidedly against these organisms belonging to the Protozoa.
It is only necessary to mention one or two forms which have been
definitely referred to the Trypanosomes. Certes, in 1882, described a
parasite from the digestive tube, including the crystalline style, of oysters,
which he named Trypanosoma balbianii. A few years ago Laveran and
Mesnil (99) re-examined this organism, and came to the conclusion that
it was not a Trypanosome but a Bacterium, allied to Spirochaeta. Other
workers who have recently observed this form also agree that its structure
shows none of the essential features of a Trypanosome, but, on the contrary^
greatly resembles that of a true Spirochaete. Perrin, it may be noted,
has endeavoured (100) to connect it with Schaudinn's bipolar " Ur-
haemoflagellate." This idea has received no support, and indeed Perrin's
whole paper is most unconvincing. Another, much more important
example is that of the remarkable spirochaetiform parasite first described
by Schaudinn and Hoffmann (103) in cases of syphilis, and which is
now considered to be most likely the cause of that disease. Schaudinn
found (102) that this organism differs in many ways from an ordinary
Spirochaeta, and placed it in a new genus Treponema as T. pallidum.
In a recent memoir (101), Krzysztalowicz and Siedlecki have given a
detailed account of this organism, and state that they have observed
distinct trypaniform stages in its life-cycle. For this reason they con-
sider it to be allied to the Trypanosomes and place it actually in the
genus Trypanosoma, as T. luia. This view lacks, as yet, corroboration,
and so here, as in the case of Schaudinn's research, the question must
1 Since this was written we are able to add that confirmation of this view is forth-
coming. In a most important note, Miyajima (Philipp. J. Sci. ser. B, ii. 1907, p.
83) describes the development of Flagellate-phases in cultures of a Piroplasma
(cf. parvum) of cattle in Japan. In seventy-two hours, forms with well-developed
undulating-membrane were numerous. The author seems to have carefully guarded
against the possibility of this highly-interesting occurrence being due to undetected
Trypanosomes present in the blood.
THE HAEMOFLAGELLATES 261
be left unsettled. There is one point, however, which may not be
without significance, namely, the considerable resemblance between the
biology of this parasite in relation to its host (i.e. as regards mode of
infection, habitat, connection with the lesions, etc.) and that of Trypano-
soma equiperdum, the cause of Dourine or " horse-syphilis " (cf. above,
pp. 197, 206).
POSTSCEIPT.
As this article goes to press, a most interesting note by Roubaud
(G.B. Ac. Sci., 24th Feb. 1908, p. 423) comes to hand. This worker
has been investigating the relation between certain lethal Trypanosomes
(T. fjambiense, T. brucii, T. dimorphon, and others) and Glossina palpalis,
and finds that the parasites undergo important changes as soon as they
arrive in the proboscis of the Tsetse-fly. The kinetonucleus passes to the
middle of the body, the undulating-membrane disappears, the flagellum
becomes short and thickened, and the parasites quickly attach themselves
to the wall of the proboscis by the flagellar end. The whole process may
be accomplished, indeed, in five minutes. Moreover, active multiplica-
tion goes on, and after a time an immense number of attached Trypano-
somes are present throughout the entire proboscis, often grouped in
masses or colonies. This " temporary culture " (culture d'attente)
persists for two days in the case of T. brucii, and longer — up to five to six
days — in the other forms.
This remarkable development is apparently specific for Glossinae ;
it only occurs in a small number, and is doubtless due to the influence of
special properties of the salivary fluid. As Roubaud remarks, it prob-
ably affords an explanation of the selective role played by the Tsetses in
the propagation of different trypanosomoses in Africa. Roubaud, how-
ever, considers that these forms found in the proboscis are the only ones
capable of giving rise to an infection in a Vertebrate after the lapse of
twenty-four hours. This is going too far, in view of the facts now known
with regard to the length of time Trypanosomes may live and develop
in the digestive tract of Glossinae (cf. pp. 200, 230). It is noteworthy that
Roubaud was unable to obtain a successful inoculation from a proboscis
so infected. Moreover, the repeated failures of investigators to infect
animals from flies after forty-eight hours (cf. pp. 199, 200) seem to show
that the later-developed " proboscis-forms " at all events are not infective,
since they may reasonably be supposed to have been present in some of
the many experiments tried. On the other hand, there is an important
observation made by Bruce when working on T. brucii, to which Mincliin
(58, p. 210) has drawn attention, showing that "wild" flies, caught
while feeding on a healthy animal, could infect another animal on which
they were subsequently fed. This certainly points to the presence of
some developmental phases in the Insect other than Roubaud's proboscis-
forms ; the proboscis had been presumably "cleaned" by the first bite —
on the uninfected animal on which the fly was caught. And this view is
entirely borne out by Stuhlmann's recent research, summarised in the body
of this article.
262
HOSTS OF THE HAEMO FLAGELLATES
LIST OF KNOWN (NATURAL) HOSTS OF TRYPANO-
SOMES AND ALLIED FORMS.
[In the compilation of this list, Nabarro's edition of Laveran and Mesnil's
Treatise has been of considerable service to the writer. ]
MAMMALIA.
? Bovidae (Indian, indigenous) .
? B. (various, African)
Buffaloes
Catoblepas gnu, gnu, "wildebeeste
? Cattle ("hill," India)
Cavia cobaya, guinea-pig
Cricetus frumenlarius (arvalis),
hamster
Hydrochoerus capybara, capybara
Lepus cuniculus, rabbit
Meles taxus, badger .
Miniopterus schreibersii, bat
Mus decumanus, se\ver-rat .
M. rattus, black rat, M. rufescens
M. sylvaticus, field rat
M. musculus, mouse .
M. niveiventer, rat (Indian)
Myotis murinv-s, a bat
Myoxus avellanarius, M. glis, dormice
Nesokia (Mus) gigantcus, bandicoot
Phyllostoma sp. See under Stegomyia
Pipistrellus pipistrellus, bat
Pteropus medius, a bat
Sciurus palmarum, squirrel (Indian) .
Spermophilus guttatus, S. musivtis,
spermophile
Strepsiceros capensis, "koodoo"
Talpa europaea, mole
Tragelaphus scriptus sylvaticus, ' ' bush -
buck "
Trypanosoma evansi (Steel).
T. theileri, Lav., and T. transvaaliense,
Lav. [most probably = T. theileri].
T. brucii, Bradford and Plimmer.
T. brucii.
T. himalayanum, Lingard (syn. T.
lingardi, Blanchard) [perhaps =
T. theileri].
A Trypanosome [possibly a Trypano-
plasma], Kunstler, 1883.
T. rabinowitschi, Brumpt (syn. Try-
panozoon criceti, Liihe).
T. equinum, Voges.
T. cuniculi, Blanchard.
T. pestanai, Bettencourt and Franga.
A Trypanosome [Dionisi, 1899].
T. lewisi (Kent) ; T. longocaudense,
Lingard [probably = T. lewisi}.
T. lewisi (Kent).
T. sp. [lewisi 1], Gros, 1845.
T. duttoni, Thiroux ; T. musculi [syn.
T. d. ?], Kendall.
T. longocaudense, Lingard [probably
= T. lewisi].
T. nicolleorum, Sergent, E. and E.
[perhaps syn. T. vespertilionis,
Battaglia].
T. blanchardi, Brumpt (syn. T. myoxi,
Blanchard).
T. bandicotti, Lingard.
T. sp. (compared with T. nicolleorum),
Petrie.
A Trypanosome [Donovan, in Lav. and
Mesn., 1904].
T. (Trypanozoon) indicum, Liihe.
A Trypanosome [Chalachnikov, 1888].
T. brucii, Br. and PI.
T. talpae, Nabarro.
T. brucii.
HOSTS OF THE HAEMOFLAGELLATES
263
Vespertilio kuhli, bat .
V. noctula, bat .....
Vesperugo nattereri, V. pipistrellus
("pipistrelle"), V. serotinus, bats
T. nicolleorum, Sergeut, E. and E. ;
T. vespertilionis, Serg. [both perhaps
synn. T. vespertilionis, Battaglia],
T. vespertilionis, Battaglia.
T. dionisii, Bettencourt and Fran9a
[perhaps syn. T. vespertilionis,
Battaglia].
Various Trypanosomes which have been given distinct names have been lately described
from certain Equiclae and Bovidae in different regions of Africa, as the cause of more or less
pronounced trypanosomosis. It is probable that some of these, at any rate, are really forms
of other better-known African parasites. They are mentioned here, in order to complete an
enumeration of species, for purposes of reference. They are T. cazalboui, Lav. ; T. congdense,
Broden ; T. nanurn, Lav. (an extremely small form); T. pecaudi, Lav. ; T. soudanense, Lav. ;
7'. mi ix, Ochmann ; and T. vivax, Ziemann. The true (natural) hosts are uncertain.
AVES.
Agelaius phoeniceus, red-winged black-
bird
Alcyon sp., kingfisher (Cameroon)
Asturinula monogrammica, hawk
(Congo State)
Athene noctua, little owl
A. brama, owl (Madras)
Buteo lineatus, red-shouldered hawk .
Bycanistes buccinator, trumpeter hnrn-
bill
Chelidon urbica, house-martin
Colaptus auratus, " flicker "
Columba sp., pigeon (Indian)
Coracias garrulu, roller-bird
Corvus sp., crow or raven (Indian)
Crane
Crithagra sp., "millet-eater"
Cyanocitta cristata, blue jay
Dryobates villosus, hairy woodpecker .
Egret
Emberiza citrinella, yellow-hammer .
Estrelda estrelda, "millet-eater"
Fringilla (Carduelis) carduelis, gold-
finch
F, coelebs, chaffinch .
Goat-sucker
T. atrium (type L. and M.), [Novy and
M'Neal, 1905].
A Trypanosome [Ziemann, 1905].
A Trypanosome [Button, Todd and
Tobey, 1907].
Trypanomorpha ( Trypanosoma) noc-
tuae (Schaud.) ; also Trypa/nosoma
[Spirocliacta ?] ziemanni (Lav.).
A Trypanosome [Donovan, in Lav. and
Mesn., 1904].
T. mesnili, Novy and M'Neal.
A Trypanosome [Button, Todd and
Tobey, 1906].
A Trypanosome [Petrie, 1905].
T. aviurn (type Lav. and Mesn.).
T. hannae, Pittaluga.
T. "avium," Banilewsky.
A Trypanosome [Hanna, 1903].
A Trypanosome ? [Gros, 1845].
T. sp. [Button and Todd, 1903].
T. avium (type L. and M.) ; also T.
sp. [Novy and M'Neal, 1905].
T. sp. incert. [Novy and M'Neal,
1905].
T. sp., perhaps avium [Cerqueira,
1906].
A Trypanosome [Petrie, 1905].
T. johnstoni, Button and Todd.
T. sp. [Sergent, E. and E. , 1904].
A Trypanosome [Ziemann, 1898 ; also
Petrie, 1905].
A Trypanosome ? [Gros, 1845].
264
HOSTS OF THE HAEMOFLAGELLATES
ffarporhynchus rufus, brown thrasher
Hirundo rustica, swallow .
Icterus galbula, Baltimore oriole .
Laniarius cruentus, shrike (African) .
Linota (Acanthis) rufescens, redpoll
Melospiza fasciata, song-sparrow .
Merula migratoria, robin (American) .
M. merula, blackbird ....
Milvus govinda, kite (Indian)
Neophron percnopterus, vulture (African )
Nicticorax gardenia (Brazil)
Padda oryzivora, Java sparrow .
Passer domesticus, sparrow . - .
Passerine birds, many (except Corvus
and Pica)
Polyplectrum germani, pheasant
(Annam)
Scolephagus carolinus, rusty blackbird
Sialia sialis, bluebird
Spinus tristis, goldfinch (American)
Sylvia atricapilla, black-cap warbler .
Syrnium aluco, tawny owl .
2'achyphormus ornata ....
Treron calva, dove (Angola)
Turdus musicus, song-thrush
Troglodytes aedon, house-wren
Zenaidura macroura, mourning-dove .
A Trypanosome [Novy and M'Neal,
1905].
T. mathisi, Serg., E. and E. ; a Try-
panosome (T. m. ?) fPetrie, 1905].
T. avium (type L. and M. ).
A Trypanosome [Neave, 1906].
T. sp. [original observation].
T. avium (type L. and M.).
T. avium (type L. and M.).
A Trypanosome [Petrie, 1905].
A Trypanosome [Donovan, in Thiroux,
1905].
A Trypanosome [Neave, 1906].
T. sp., perhaps avium [Aragao, in Cer-
queira, 1906].
T. paddac, Thiroux.
T. avium (type L. and M.).
Trypanosomes [Sjb'bring, in N. and
M'Neal, 1905].
T. polyplectri, Vassal.
T. sp., Novy and M'Neal.
T. avium (type L. and M. ).
T. laverani, Novy and M'Neal.
T. sp. [Sergent, E. and E., 1904].
T. avium, Danil., emend. Lav. ; also
"T." [Leucocytozoon] ziemanni (Lav.).
A Trypanosome [Cerqueira, 1906].
A Trypanosome [Wellmau, 1905].
A Trypanosome [Petrie, 1905].
A Trypanosome [N. and M'N., 1905].
T. avium (type L. and M.).
REPTIMA.
Crocodile (Uganda; ....
Crocodilus cataphractus ? (Congo)
Damonia reevesii, tortoise .
Gecko
Mabuia raddonii, a lizard (French
Guinea)
Python . . .
Snake (unspec., Gambia)
Tortoise (Indian — Emys or Kachuga
tectum)
Tortoise (unspec., Gambia)
A Trypanosome [Minchin, Gray and
Tulloch, 1906].
A Trypanosome [Dutt., Todd and Tob.,
1907].
T. damoniae, Lav. and Mesn.
A Trypanosome [Gehrke, 1903].
T. boueti, Martin.
" T." pythonis, Robertson [really a
Haemogregarine].
A Trypanosome [Dutton and Todd,
1903].
A Trypauosome [Simond, in L. and M.,
1904].
A Trypanosome [Dutton and Todd,
1903].
HOSTS OF THE HAEMOFLAGELLATES
265
AMPHIBIA.
Bufo vulgaris and viridis, toads .
B. rcticulatus (Somaliland) .
Diemyctulus viridescens (American
newt)
Frogs (unspec., Gambia)
Hyla arborca and H. viridis, tree-frogs
//. latcristriga (?), Brazil
Rana angolcnsis (Transvaal)
H. esculcnta, edible frog
7i. temporaria
7v'. t. (?) (Hong Kong) .
.K. theileri (Transvaal)
It. trinodis (?) and other sp. (Gambia)
T. rotatorium (Mayer).
T. somalcnse, Brumpt.
A Trypanosome [Tobey, 1906].
T. mega and T. karyozeukton, Duttoii
and Todd.
T. rotatorium (Mayer); T. sp. [?],
Lav. and Mesn.
T. borreli, Marchoux and Salimbeni.
T. nelspruitense, Lav.
T. rotatorium (Mayer). (Syn. T.
loricatum or costatum (Mayer) and
T. rotatorium (Mayer), Fran9a and
Athias ; T. r. var. nana, Sergent, E.
and E. ; T. inopinalum, Sergent,
E. and E. ; T. elegans and T. undu-
lans, F. and A. [doubtful species].)
T. rotatorium (Mayer).
T. belli, Nabarro.
T. nelspruitense, Lav.
T. rotatorium (Mayer).
PISCES.
(Tpl. — Trypanoplasma.)
Abramis brama, bream
Acerina cernua, pope ....
A nguilla vulgar is, eel ...
Bageus bayard, bagara (Nile)
Barbus camaticus (India) .
B. fluviatilis, barbel ....
Blennius pholis, blenny
Bothus rhombus (Rhombus laevis), brill
Box boops ......
Callionymus dracunculus .
Carassius auratus, goldfish
C. vulgaris, Prussian carp .
Clarias (Silurus) clarias, a Silurid
(Cochin-China)
C. angolensis (Congo State)
Cobitis barbatula, loach
T. abramis, Lav. and Mesn. ; Tpl.
abramidis, Brumpt.
T. accrinae, Brumpt ; & Trypanoplasm
[Keysselitz, 1906].
T. granulosum, Lav. and Mesn.
A Trypanosome [Neave, 1906].
A Trypanosome [Lingard, 1904].
T. barbi, Brumpt ; Tpl. barbi,
Brumpt.
T. delagei, Brumpt and Lebailly.
T. bothi, Lebailly.
Tpl. [?] intestinalis, Leger.
T. callionymi, Brumpt and Lebailly.
T. danilewskiji, Lav. and Mesn.
T. carassii (Mitropban.). (Syn. Haema-
tomonas c., Mitis ; T. piscium and T.
fusiforme piscium, Danilewsky. )
T. clariac, Montel.
A Trypauosome [Button, Todd and
Tobey, 1906].
T. barbatulae, L^ger ; Tpl. varium,
L^ger.
266
HOSTS OF THE HAEMO FLAGELLATES
C. fossilis .
Coitus bubalis
C. gobio, river bull-head
Cycloptcrus lumpus, lump-fish
Cyprinus carpio, carp ....
Esox lucius, pike ....
Gobio fluviatilis, gudgeon .
G. giuris (India) ....
Gobius niger, goby ....
Leuciscus (Scardinius), erythroph-
thalmus, rudd or red-eye
L. idus, L. cephalus, L. rutilus, roaches
L. spp
Limanda platessoides ....
Lota vulgaris .....
Macrodon malabaricus (Brazil) .
Macrones seenghala, M.tengara,Si\nri(.\s
(India)
M. cavasius (India) ....
Mugil sp., noke (Nile)
OphiocepJialus striatus, Silurid (India)
Perca fluviatilis, perch
Phoxinus lacvis, minnow
Platoplirys laternae .
Pleuronectcs flesus (Flesus vulgaris),
flounder
P. platessa (Platessa vulgaris), plaice .
Polypterus sp., dabib (Nile)
Raia clavata, E. macrorhynchus, B.
mosaica, and E. punctata, rays
E. microccllata .....
Ehamdia queler (Brazil)
Saccobratichus fossilis, a Silurid .
Salmo fario, trout .
Scyllium canicula, S. stellare, dogfish
T. cobitis (Mitroph. ). (Syn. Haemato-
monas c., Mitr. ; T. piscium and
T. fusiformc, Daiiilewsky. )
T. cotti, Brumpt and Lebailly.
T. langeroni, Brumpt ; Tpl. guernei,
Brumpt.
Tpl. [?] ventricuU, Keysselitz.
T. danilewskiji, Lav. and Mesn. ; Tpl.
cyprini, Plehn.
T. remaki, Lav. and Mesn. ; Tpl. sp.
[Minchin, 1908].
T. elegans, Brumpt.
T. sp. [Castellani and Willey, 1905].
T. gobii, Brumpt and Lebailly.
Tpl. Worrell, Lav. and Mesn. ; T.
scardinii, Brumpt.
A Trypanosome and Trypanoplasm
[Keysselitz, 1906]. [Probably Tpl.
borreli and T. leucisci.]
T. leucisci, Brumpt.
T. limandae, Brumpt and Lebailly.
A Trypanosome and Trypanoplasm
[Keysselitz, 1906]. .
T. macrodonis, Botello.
A Trypanosome [Lingard, 1899].
A Trypanosome [Castellaui and
Willey, 1905].
A Trypanosome [Neave, 1906].
A Trypanosome [Lingard, 1899].
T. percae, Bmmpt ; also a Trypauo-
plasm [Keysselitz, 1906].
T. danilewskyi (?), Lav. and Mesn.; T.
phoxini, Brumpt ; Tpl. borreli, Lav.
and Mesn.
T. laternae, Lebailly.
T. flesi, Lebailly (syn. T. pleuro-
nectidium, Robertson).
T. platessae, Lebailly (syn. T. pleuro-
nectidium, Roberston).
A Trypanosome [Neave, 1906].
T. raiae, Lav. and Mesn.
A Trypanosome [Robertson, 1906].
T. rhamdiae, Botello.
T. saccobranchi, Castellani and Willey.
Tpl. truttae, Brumpt. [Valentin, in
1841, observed a Haematozoan,
which was probably either a
Trypanosome or a Trypanoplasm.]
T. scyllii, Lav. and Mesn.
HOSTS OF THE HAEMOFLAGELLATES
267
tiilurus giants ....
Solea vulgaris, sole
Squalius (Leuciscus) cephalits, chub
Synodontis schal, gargur (Xile) .
T!i»''i tinea, tench
Trichognster fasciatus (India)
A Trypanosome [Keysselitz, 1906].
T. soleae, Lav. and Mesu.
T. squalii, Brumpt.
A Trypanosome [Neave, 1906].
T. tincae, Lav. and Mesn. ; a Trypano-
plasm [Keysselitz, 1906],
A Trypanosome [Lingard, 1899].
INSECTA.
Anopheles maculipennis
A. m. (larvae) ....
Anopheles sip., mosquitoes (India)
Bombyx mori, silkworm
Chironomus plumosus
Cimex rotundatus, bed-hug (India)
Culexfatigans ....
C. pipiens .....
Dasyphora pratorum .
Glossina fusca ....
G. morsitans and G. pallidipes .
G. jtalpalis ....
G. tachinoides ....
Haematopinus spinulosus, rat-louse
Haematopota italica
Hippobosca rufipes, (?) //. maculata
Homalomyia scalaris .
Mclophagus ovinus, sheep-louse .
Musca domestica .....
Nepa cinerea .....
Pollenia rudis .....
Pulex sp., fleas .....
Sarcophaga haemorrhoidalis, blow-fly
Stcgomyia fasciata ....
S. f. (an individual which had fed on
a bat, Phyllostoma)
Stomoxys calcitrans ....
Tabanus rjlaucopsis ....
Crithidia fasciculata, L^ger.
A Herpetomonad (cf. with H. jaculum)
[Sergent, E. and E., 1906].
Herpetomonads (said to resemble
Leger's Crithidia) [Ross, 1898 ;
Christophers, 1901, and others].
Herpetomonas bombycis, Levaditi.
Crithidia campanulata, Leger.
Leishmania (Piroplasma) donovani.
Herpetomonads [Ross, 1898 ; Chris-
tophers, 1901 ; Patton, 1907].
Trypanomorpha nociuae (Schaud.) ;
Crithidia fasciculata ; " Trypano-
soma" (Herpetomonas) culicis, N.,
M'N., and Torrey ; H. algeriense,
Sergent, E. and E. ; H. sp., indet.
[Patton, 1907].
H. lesnei, Leger.
T. brucii ; perhaps T. gambiense.
(?) T. brucii.
T. grayi, Novy ; T. tidlochii, Minchin ;
(?) T. dimorphon, Dutt. and Todd.
(?) T. brucii ; (?) T. gambiense.
(?) T. lewisi.
(?) //. subulata, Leger.
T. thcileri (probably).
//. (cf. muscae-domesticae) [Leger].
" Trypanosome-like parasites " [Pfeiffer,
1905].
If. muscae-domesticae, Burnett.
//. jaculum, Leger.
//. (cf. m.-d.) [Leger].
T. lewisi (probably) ; a Herpetomonad
[Dalfour, 1906].
H. sarcophagae, Prowazck.
//. algeriense, Sergent, E. and E.
A "Trypanosome" [Durham, 1900].
(?) T. equinum ;
[Gray, 1906].
//. subulata, Leger.
a Herpetomonad
268 HOSTS OF THE HAEMOFLAGELLATES
T. lineola and other sp. . . . (?) T. evaiisi.
T. tergestimis ..... Herpetomonas (Crithidia) minuta,
Le"ger.
Tanypus sp H. gracilis, Ldger.
Theicomyxa fusca .. . . . H. (cf. m.-d.} [Leger].
"Water-bug" (India) ... A Herpetomonad [Patton, 1907].
ARACHNIDA.
Ehipicephalus sanguineus, dog-tick " T." christophcrsi, N.. M'N. , and
(India) Torrey.
HlRUDINEA.
Calobdella punctata .',»- . . . T. cotti and T. soleae [Brunipt].
Helobdella algira . . . . T. inopinatum [Billet].
Hemiclepsis marginata . . . Tpl. varium [Le'ger].
H. sp. ...... T. abramis, acerinac, barbi, dani-
leivsfcyi,granulosum,percae,phoxini,
remaki, squalii; perhaps also T.
barbatulae (?), langeroni, Icucisci,
scardinii [Brumpt]. Tpl. abramidis
[Briimpt].
Piscicola sp. ..... T. barbatulae [Leger] ; Tpl. borreli,
barbi, guernci, (tytruttae [Brumpt].
P. geometra Tpl. borreli ; also other Trypanoplasms
[Keysselitz].
Pontobdella muricata T. raiae [Robertson].
P. sp. ...... T. scyllii [Brumpt].
SlPHONOPHORA.
Abyla pentagona, Cucubalus kochii, Trypanophis grobbeni (Poohe).
Halistemma tergestinum, and Mono-
phycs gracilis
LITERATURE.
I. Relating to the Trypanosomes.
A. Comprehensive works.
1. Laveran, A., and. Mesnil, F. Trypanosomes et try panosomiases. Paris (Masson
et Cie.), 1904. An English edition, translated and considerably enlarged
and brought up to date by D. Nabarro, has lately been published (Londou,
Bailliere, Tindall and Cox, 1907, 581 pp., 81 text-figg.).
2. Liihe, M. Die im Blute schmarotzenden Protozoen. In Mense's Handbuch
der Tropenkrankheiten, vol. iii. pt. i. (Leipzig, J. A. Barth, 1906), pp. 69-
268, 3 pis., text-figg.
3. Woodcock, H. M. The Haemoflagellates. Q.J. Micr. Sci. 1., 1906, pp.
151-331, 65 text-figg.
LITERATURE OF THE HAEMOFLAGELLATES 269
B. List of the more important memoirs cited in the text. (N.B. Full
references to the existing literature are given in each of the above works.)
4. Billet, A. Culture d'un Trypanosome de la grenouille chez tine Hirudinee :
relation atitogenique possible de ce Trypanosome avec tine Hemogregarine.
O.K. Ac. Sci. cxxxix. p. 574, 1904.
5. Sur le Trypanosoma inopinatvm . . . et sa relation possible avec les
Drepanidium. C.R. Soc. Biol. Ivii. p. 161, 16 figg., 1904.
6. Bradford, J. II. , and Plimmer, H. G. The Trypanosoma brucii, the Organism
found in Nagana or the Tsetse-fly Disease. Q.J. Micr. Sci. xlv. p. 449,
2 pis., 1902.
7. Bruce, D. Reports on the Tsetse-fly Disease or Nagana. Ubombo, Zululand,
1895 and 1896-; London, 1897 and 1903.
8. , Nabarro, D., and Greig, E. D. [Reports on Sleeping-Sickness and various
Animal Trypanosomoses in Uganda.] Roy. Soc. Comm., 1903-1907.
9. Bruin/it, E. Contribution a 1'etude de 1'evolution das Hemogregarines et des
Trypauosomes. C.R. Soc, Biol. Ivii. p. 165, 1904.
10. Sur quelques especes nouvelles de Trypauosomes parasites des poissons
d'eau douce ; leur mode devolution. Op. cit. Ix. p. 160, 1906.
11. Mode de transmission et evolution des Trypanosomes des poissons ;
description de quelques especes de Trypanoplasmes des poissons d'eau douce ;
Trypanosome d'un crapaud africain. T.c. p. 162, 1906.
12. Experiences relatives au mode de transmission des Trypanosomes et
des Trypauoplasmes par les Hirudinees. Op. cit. Ixi. p. 77, 1906.
13. Role pathogeue et mode de transmission du Trypanosoma inopinatum,
Ed. et Et. Sergent. Mode d'inoculatiou d'autres Trypanosomes. T.c.
p. 167, 1906.
14. - - De 1'heredite des infections a Trypanosomes et Trypanoplasmes chez
les hotes intermediares. Op. cit. Ixiii. p. 176, 1907.
15. and Lebailly, C. Description de quelques nouvelles especes de
Trypanosomes et d'Hemogregarines parasites des Teleosteens marins.
C.R. Ac. Sci. cxxxix. p. 613, 1904.
16. Buffard, M., and Schneider, G. Le Trypanosome de la Dourine. Arch.
Parasitol. iii. p. 124, pis., 1900.
17. Castellani, A. Trypanosoma and Sleeping-Sickness. Reports S.S. Comm.
Roy. Soc. i. and ii., 1903.
18. Danilewsky, . Recherches sur la parasitologie comparee du sang des
oiseaux. Kharkotf, 1888-1889.
19. Zur Parasitologie des Blutes. Biol. Centrlbl. v. p. 529 (1885).
20. Dutton, E. Note on a Trypanosoma occurring in the Blood of Man. Brit.
Med. Jouru., 1902, ii. p. 881, 1 fig.
21. and Todd, J. L. First Report of the Trypanosomosis Expedition to
Senegambia (1902). Mem. Livpl. Sch. Trop. Med. No. 11, 1903.
22. Franca, C., and Athias, C. Recherches sur les Trypanosomes des Amphibiens :
I. Les Trypanosomes de la Eana esculenta. Arch. Inst. R. Bact.,
Lisbonne, i., 1906.
23. Gray, A. C., and Tulloch, F. M. The Multiplication of the Trypanosoma
gambiense in the Alimentary Canal of Glossina palpalis. Rep. S.S. Comm.
Roy. Soc. No. 6, p. 282, 1 pi., 1905.
24. Gruby. Recherches et observations sur une nouvelle espece d'Hematozoaira
(Trypanosoma sanguinis). C.R. Ac. Sci. xvii. p. 1134, 1843; and Ann.
Sci. Nat. (3), i. p. 105, 7 figg., 1844.
270 LITERATURE OF THE HAEMOFLAGELLATES
25. Hanna, W. Trypanosoma in Birds in India. Q.J. Micr. Sci. xlvii. p. 433,
1 pi., 1903.
26. Keyssclitz, G. Ueber Trypanophis grobbcni (Trypanosoma g., Poche). Arch.
Protistenk. iii. p. 367, 3 figg., 1904.
27. Generations- und Wirthswechsel von Trypanoplasma borreli, Lav. et
Mesn. Arch. Protistenk. vii. p. 1, text-figg., 1906.
28. Koch, A'. Vorlaufige Mittheilungen iiber die Ergebnisse meiner Forschungs-
reise nach Ostafrika. Deutsch. med. Wocheuschr., 1905, p. 1865,
text-figg.
29. Ueber den bisherigen Verlauf der deutschen Expedition zur Erforsch-
ung der Schlafkrankheit in Ostafrika. Op. cit. 1906, Appendix, p. 51 ;
also 1907, p. 49. Schluss-Bericht. Op. cit. 1907, p. 1889.
30. Lankester, E. R. On Undulina, the type of a New Group of Infusoria. Q.J.
Micr. Sci. xi. p. 387, 4 figg., 1871.
31. - - The Sleeping-Sickness. Quart. Rev., July 1904, p. 113, 7 figg.
32. Laveran, A. Sur un nouveau Trypanosome des Bovides. C.R. Ac. Sci.
cxxxiv. p. 512, 1902.
33. Au sujet de deux Trypanosomes des Bovides du Transvaal. Op. cit.
cxxxv. p. 717, 5 figg., 1902.
34. Sur un Trypanosome d'une chouette. C.R. Soc. Biol. Iv. p. 528,
2 figg., 1903.
35. Contribution a 1'etude de Hacmamoeba ziemanni. T.c. p. 620,
7 figg., 1903.
36. Sur une nouveau Trypauosome d'une grenouille. Op. cit. Ivii. p. 158,
2 figg.', 1904.
37. and Mesnil, F. Recherches morphologiques et experimentales sur le
Trypanosome des rats, Tr. lewisi (Kent). Ann. Inst. Pasteur, xv. p. 673,
2 pis., 1901.
38. and Sur les Flagelles a membrane ondulante des poissons (genus
Trypanosoma, Gruby, et Trypanoplasma, n. gen.). C.R. Ac. Sci. cxxxiii.
p. 670, 1901.
39. and Sur la structure du Trypanosome des grenouilles et sur
1'extension du genre Trypanosoma, Gruby. C.R. Soc. Biol. liii. p. 678,
3 figg., 1901.
40. and Sur les Hematozoaires des poissons marins. C.R. Ac. Sci.
cxxxv. p. 567, 1902.
41. and Sur quelques Protozoaires parasites d'une tortue d'Asie
(Damonia reevesii). T.c. p. 609, 14 figg., 1902.
42. and Des Trypanosomes des poissons. Arch. Protistenk. i. p. 475,
15 figg., 1902.
43. and Recherches morphologiques et experimentales sur le
Trypanosome du Nagana ou maladie de la mouche tse-tse. Ann. Inst.
Pasteur, xvi. p. 1, 13 figg., 1902.
44. and Sur un Trypanosome d'Afrique pathogene pour les Equides,
T. dimorphon, Button et Todd. C.R. Ac. Sci. cxxxviii. p. 732, 7 figg.,
1904.
45. Lebailly, C. Sur quelques Hemoflagelles des Teleosteens marins. Op. cit.
cxxxix. p. 576, 1904.
46. Lfyer, L. Sur la structure et la mode de multiplication des Flagelles du
genre Herpetomonas, Kent. C.R. Ac. Sci. cxxxiv. p. 781, 7 figg.,
1902.
271
47. Ltger, L. Sur un Flagelle parasite de 1' Anopheles mnculipennis. C.R. Soc.
Biol. liv. p. 354, 10 figg., 1902.
48. Sur quelques Cercomonadines nouvelles ou peu connues parasites de
1'intestiu des Insectes. Arch. Protistenk. ii. p. 180, 4 figg., 1903.
49. Sur la morphologie du Trypanoplasma des vairoiis, et sur la structure
et les affinites des Trypauoplasmes. C.R. Ac. Sci. cxxxviii. pp. 834,
856, 5 figg., 1904.
50. Sur les Hemoflagelles du Colitis barbatula, L. ; Trypanosma barbatulae,
n. sp. ; et Trypanoplasma varium, n. sp. C.R. Soc. Biol. Ivii. pp. 344, 345,
1904.
51. Sur tin nouveau Flagelle parasite des Tabauids. T.c. p. 613, 6 figg.,
1904.
52. Sur les affinites de 1' ' Herpetomonas subulata et la phylogenie des
Trypanosomes. T.c. p. 615, 1904.
53. Sur la presence d'un Trypanoplasma intestinal chez les poissons.
Op. cit. Iviii. p. 511, 1905.
54. Lignieres, J. Contribution a 1'etude de la trypanosomose des Equides
Sud-Americains connue sous le nom de Mai de Caderas (Trypanosoma
elmassiani). Rec. Med. Vet. Bull, et Mem. (8), x. pp. 51, 109, 164,
2 pis., 1903.
55. Lingard, A. A new Species of Trypanosome found in the Blood of Rats
(India), etc. J. Trop. Vet. Sci. i. p. 5, 1 pi., 1906.
56. M'Neal, W. J. On the Life-History of T. lewisi and T. brucii. J. Inf.
Diseases, i., Nov. 1904.
57. Minchin, E. A. On the Occurrence of Encystation in Trypanosoma grayi,
Novy, etc. P. Roy. Soc. Ixxix. B, p. 35, text-figg., 1907.
58. Investigations on the Development of Trypanosomes in Tsetse-flies,
etc. Q.J. Micr. Sci. Hi. p. 159, 6 pis., 1908.
59. , Gray, A. C., and Tulloch, F. At. Glossina palpalis in its Relation to
Trypanosoma gambiense and other Trypanosomes. P. Roy. Soc. Ixxviii. B,
p. 242, 3 pis., 1906.
60. Mitrophanow, . Beitrage zur Kenntniss der Hamatozoen. Biol. Centrlbl.
iii. p. 35, 2 figg., '1883.
61; Novy, F. G. The Trypanosomes of Tsetse-flies. J. Inf. Diseases, iii. p. 394,
3 pis., 1906.
62. and M'Xeal, W. J. On the Trypanosomes of Birds. Op. cit. ii. p. 256,
11 pis., 1905.
63. and — - On the Cultivation of Trypanosoma brucii. Op. cit. i. p. 1,
1904.
64. , , and Torrey, H. N. The Trypanosomes of Mosquitoes and
other Insects. Op. cit. iv. p. 223, 7 pis., 1907.
65. Patton, W. S. Preliminary Note on the Life-Cycle of a Species of Herpeto-
monas found in Culex pipiens. B.M.J., 1907, ii. (July 13th).
66. Plchn, M. Trypanoplasma cyprini, n. sp. Arch. Protistenk. ii. p. 175, 1 pi.,
1903.
67. Pricolo, A. Le Trypanosome de la souris. Cycle de developpement des Try-
panosomes chez le fetus. Centralbl. Bakt., Abt. 1, xlii. Orig. p. 231, 1906.
68. Prowazek, S. Studien iiber Saugethiertrypanosomen. Arb. kais.
Gesundhtsa. xxii. p. 1, 6 pis., 1905.
69. Die Eutwickelung von Herpetomonas, einen mit den Trypanosomen
verwandten Flagellaten. Op. cit. xx. p. 440, text-figg., 1904.
272 LITERATURE OF THE HAEMOFLAGELLATES
70. Rabinowitsch, L., and Kempner, W. Beitrage zur Kenntniss der
Blutparasiten, speciell der Rattentrypanosomen. Zeitschr. Hyg. xxx.
p. 251, 1 pi., 1899.
71. Robertson, M. Notes on Certain Blood-inhabiting Protozoa. Proc. Physic.
Soc. Edinb. xvi. p. 232, 2 pis., 1906.
72. Studies on a Trypanosome found in the Alimentary Canal of Ponlob-
della muricata. Op. cit. xvii. p. 83, 4 pis., 1907.
73. Rogers, L. The Transmission of the Trypanosoma eransi in India by Horse-
flies, etc. Proc. Roy. Soc. Ixviii. p. 163, 1901. Also see B.M.J., 1904,
ii. p. 1454.
74. Ross, 11. Notes on the Parasites of Mosquitoes found in India between 1895
and 1899. Journ. Hyg. vi. p. 101, 1906.
75. Schaudinn, F. Generations- uud Wirthswechsel bei Trypanosoma und
Spirochaeta. Arb. kais. Gesundhtsa. xx. p. 387, text-figg., 1904.
76. Sergent, E. and E. Sur un Trypanosome nouveau parasite de la grenouille
verte. C.R. Soc. Biol. Ivi. p. 123, 1 fig., 1904.
77. Hemamibes des oiseaux et moustiques. Generations alternantes de
Schaudinn. Op. cit. Iviii. p. 57, 1905.
78. Sur des Trypanosomes des chauves - souris. T.c. p. 53, 2 figg.,
1905.
79. Sur un Flagelle" nouveau de 1'intestin des Culex et des Stegomyia,
Herpetomonas algeriense. Op. cit. Ix. p. 291, 1906.
80. Stuhlmann, F. Beitrage zur Kenntniss der Tsetsefliegen (Gl. fusca and Gl.
tachinoides). Arb. kais. Gesundhtsa. xxvi. p. 83, 4 pis., 1907.
81. Swingle, L. D. Some Studies on Trypanosoma lewisi. Trans. Amer. Micr.
Soc. xxvii. p. Ill, 1 pi., 1907.
82. Thiroux, . Sur un nouveau Trypanosome des oiseaux. C.R. Ac. Sci.
cxxxix. p. 145, 5 figg., 1904.
83. Recherches morphologiques et experimentales sur les Trypanosoma,
paddae. Ann. lust. Pasteur, xix. p. 65, 1 pi., 1905.
84. Recherches ... sur Trypanosoma duttoni, Thiroux. T.c. p. 564,
1 pi., 1905.
85. Voges, 0. Mai de Caderas. Zeitschr. Hyg. xxxix. p. 323, 1 pi., 1902.
86. Wasielewsky and Senn, G. Beitrage zur Kenntniss der Flagellaten des.
Rattenblutes. Op. cit. xxxiii. p. 444, 3 pis., 1900.
II. Relating to the ' ' Leishman- Donovan- Wright " Bodies.
87. Christophers, S. R. Reports on a Parasite found in Persons suffering from
Enlargement of the Spleen in India. Sci. Mem. India, Nos. 8, 11, 15,
1904-1905.
88. Donovan, C. Human Piroplasmosis. Lancet, 1904, ii. p. 744, 1 pi.
89. James, S. P. Oriental or Delhi Sore. Sci. Mem. India, No. 13, 1905.
90. Laveran, A., and Mesnil, F. Sur un Protozoaire nouveau (Piroplasma
donovani, Lav. et Mesn.), etc. C.R. Ac. Sci. cxxxvii. p. 957, 17 figg.,
1903 ; and op. cit. cxxxviii. p. 187, 1904.
91. Leishman, W. On the Possibility of the Occurrence of Trypanosomosis in
India. Brit. Med. Journ. 1903, i. p. 1252, 2 figg. ; see also op. cit.,
1904, i. p. 303.
92. and Statham. The Development of the Leishman Body in
Cultivation. Journ. Army Med. Corps, iv. p. 321, 1 pi. 2 figg., 1905.
LITERATURE OF THE HAEMOFLAGELLATES 273
93. Patton, W. S. Prelim. Report on the Development of the Leishman-
Donovan Body in the Bed-Bug. Sci. Mem. India, No. 27, 1907.
94. Rogers, L. On the Development of Flagellated Organisms . . . from the
Spleen Protozoic Parasites of Kala-Azar. Q.J. Micr. Sci. xlviii. p. 367,
1 pi., 1904.
95. Further Work on the Development of the Herpetomonas of Kala-
Azar . . . from the Leishmau-Donovan Bodies. Proc. Roy. Soc. Ixxvii. B,
p. 284, pi. 7, 1906 ; see also Lancet, 1905, i. p. 1484.
96. floss, It. A New Parasite of Man. Thorn pson-Yates Lab. Rep. (5), 2,
p. 79, 1 pi., 1904.
97. Wright, J. H. Protozoa in a Case of Tropical Ulcer (Delhi Sore). Journ.
Med. Research, Boston, x. p. 472, 4 pis., 1903.
C. Relating to the Spirochaetae.
98. Certes, A. Note sur les parasites et les commensanx de 1'huitre. Biol.
Soc. Zool. France, vii. p. 347, 1 pi., 1882 ; see also op. cit. xvi. pp. 95 and
130, 1891.
99. Laveran, A., and Mesnil, F. Sur la nature bacterienne du pretendu
Trypauosome des huitres, " T." balbianii. C.R. Soc. Biol. liii. p. 883,
1901.
100. Perrin, W. S. Researches upon the Life -History of " Trypanosoma "
balbianii (Certes). Arch. Protistenkunde, Jena, vii. p. 131, 2 pis.,
1906.
101. Krzysztalowicz, F., and Siedlecki, M. Contribution a 1'etude de la struc-
ture et du cycle evolutif de Spirochaeta pallida, Schaud. Bull. Ac.
Cracovie, 1905, p. 713, 1 pi.
102. Schaiulinn, F. Zur Kenntniss der Spirochaeta pallida. Deutsch. med.
Wochenschr. No. 42, 1905, p. 1665 ; see also t.c. p. 1728 (gen.
Treponeina proposed).
103. and Hoffmann, E. Vorlaufiger Bericht ueber das Vorkommen
von Spirochaeten in syphilitischen Krankheitsproducten. Arb. kais.
Gesundhtsa. xxii. p. 527, 1905.
APPENDIX A.1
CHLAMYDOMYXA.
THIS genus is represented by two species. C. labyrinthuloides was dis-
covered by Archer in pools in moorland country in Ireland and
described by him in 1875 (1). It has subsequently been investigated
by Geddes (2) in material supplied by Archer ; and by Hieronymus (3),
who found it in the Riesengebirge and elsewhere in Germany. 0. mon-
tana was first described by Lankester (5) and obtained by him in
Sphagnum swamps in Switzerland, and has since been investigated by
Penard (6).
Two main phases of the life-history are in many respects well
known — a free active stage, with pseudopodia more or less extended, and
a (much commoner) encysted stage ; and we now have evidence, though
it is still incomplete, of stages of multiplication by fission and of spore-
formation.
Chlamydomyxa unites in a remarkable manner the holophytic and
holozoic modes of nutrition. The protoplasmic body is crowded with
chromatophores, by means of which it is able to increase largely in size in
the encysted state ; but it is also able, in its active phase, to engulf and
to digest animal and vegetable organisms.
The body consists of hyaline protoplasm containing nuclei, chromato-
phores, and small refracting bodies — the "oat-shaped corpuscles" of
Lankester. In the encysted condition it may form a globular mass,
measuring, when fully grown, 60-90 p in diameter in C. labyrinthuloides,
the cysts of C. montana being a little smaller.
The nuclei (Fig. 1, a, b, and d) vary from 1 '5 to 3 //, in diameter. They
are generally evenly distributed through the protoplasm, and they increase
in number with its growth. In the large cysts of C. labyrinthuloides
there may be as many as 32 or more ; in C. montana, according to Penard,
100 or more. They contain a nucleolus or group of nucleoli at the
centre, and there are indications of a nuclear . reticulum at the periphery.
Their mode of division is, according to Hieronymus, intermediate between
mitosis and amitosis. In life they are visually hidden by the chromato-
phores, and thus escaped the notice of the earlier observers.
The chromatophores are oval bodies varying in size up to 3 //, (C. mon-
tana) and 5'5 /A (G. labyrinthuloides, Fig. 1, d). They consist of coloured
1 By J. J. Lister, M.A., F.R.S., Fellow of St. John's College, Cambridge.
2/4
APPENDIX
275
and colourless tracts, which are apparently differently distributed in the two
species. The colour varies from grass-green to olive-green, yellow, and
brown, and is dependent on the presence, in varying proportions, of
chlorophyll and of a yellow-brown colouring matter (? diatomin). They
aft
PIG. 1.
Chlamydomyxa labyrinthuloides. a and 6, cysts from leaf-cells of Sphagnum, constricted by
the characteristic annular bands of the latter, from stained preparations showing the chromato-
phores and nuclei, x 620. c, end of a living cyst, treated with weak methylene blue solution.
The chromatophores are shaded. The nuclei are not seen, x 5000. d, nuclei highly magnified ;
c, /, living chromatophores ; g, chromatophore after treatment with Flemming's fluid and
fuchsin ; h, oat-shaped corpuscles ; e-h x about 10,000. (After Hieronymus.)
appear to multiply by binary fission (Fig. I,/). The absence of a cellulose
envelope and of a nucleus, as well as other characters of the chromatophores,
prevent their being regarded as symbiotic algae. As a degeneration
product, and especially under the influence of bright sunlight, the
colouring matter breaks down, producing a red or brown fatty substance
^lipochrome) which accumulates in drops in the interior of the cysts, and,
276 APPENDIX
by its colour, reveals the presence of Chlamydomyxa when it is present in
abundance on the vegetation of a pool.
The oat-shaped corpuscles ("spindles" of Archer, "physodes" of
Hieronymus) are shining, highly-refracting bodies, homogeneous or faintly
laminated, of a pale bluish tint and semifluid consistence (Fig. 1, h).
They are round or oval in shape, but become longer (oat-shaped) when
drawn out on the pseudopodial filaments. They vary in size up to about
2 p. in length. As regards composition, Hieronymus identifies them with
phloroglucin, a member of the aromatic series which occurs in the
Fucaceae.
When Chlamydomyxa was discovered the resemblance between these
bodies, held in the expanded, stiff pseudopodial network (Fig. 3 (2)) and
the nucleated units of the associations of Labyrinthula, suggested the view
that they might be of similar nature, although nothing of a nuclear
character could be revealed in the corpuscles by stains, and they are,
moreover, much smaller than the units of Labyrinthula. The evidence
which we now have as to the nuclei of Chlamydomyxa, and as to the
chemical nature of these bodies, prevents our acceptance of this view.
They are probably to be regarded as reserve food material (possibly in
relation with the metabolism of cellulose) stored in a granular form.
Crystals of oxalate of lime, formed doubtless in the katabolic pro-
cesses, are also present in the cell-fluids, and they may be crowded in
vacuoles of the encysted animal, to be expelled when it emerges.
The cysts of Chlamydomyxa are found in great abundance within the
large cells of the leaves of Sphagnum, or between the cells of other
aquatic plants (Hypnum, Eriocaulon, cotton-grass, etc.). They may also
be found on the surface of these and other submerged bodies.
They are invested by a cellulose envelope, often consisting of several
laminae added one within another, and the investment appears to be of a
plastic consistency, expanding with growth so as to cover large protrusions
of the cyst which extend through apertures in the cell-wall, and it may
close in about portions which are withdrawn from deeper recesses of the
plant tissue. Considerable growth of the protoplasmic body may occur
in the encysted condition, a result dependent on the holophytic nutrition
brought about by the agency of the chromatophores. The youngest
cysts found in a Sphagnum leaf are very small and contain a single
nucleus. As they increase in size and become limited by the walls of the
elongated leaf-cells they grow in length (Fig. 1, a and 6). The cysts may
finally break through the wall of the cell and project in lobate prominences
to the exterior. The activities of the encysted organism do not, however,
result in uniform growth, for many cysts have shrunken contents, and
have formed a fresh wall separate from the original one, and in the
space between the envelopes groups of the red oil- globules referred to
above may lie, discharged before the inner wall was secreted. Moreover,
the contents of a cyst may undergo division within the envelope into two
or more parts, and each part then forms a wall of its own.
When the cysts are fully grown and favourable conditions occur, an
aperture is formed in the envelope, presumably by the solvent action of
the protoplasm on the cellulose, and the contents emerge in the free state.
APPENDIX 277
The accounts of the behaviour of the organism in the free state differ
considerably and are not easy to reconcile.
In G. labyrintJmloides, as described by Archer (cp. his figure in the
Q.J.M.S. vol. xv. Plate vi., from which Fig. 3 (2) is taken), the proto-
plasmic body was still partially contained in the cyst. Extending
through the aperture, it was produced into a dendriform system of
branches, diminishing in thickness. From the ends and sides of the
branches filiform hyaline pseudopodia of small but uniform thickness
reach far out into the water. The chromatophores are not seen in
relation with the filaments, but these are plentifully beset with the oat-
shaped corpuscles. The latter are drawn out in the direction of the
filament, and slowly travel along it in one direction or the other. The
filaments are sparingly branched ; whether or not they anastomose,
observers are not agreed. They have a " stiff but flexible " (Penard)
consistency. Lankester is inclined to regard the filaments as " inert
products of the metamorphosis " of the protoplasm, over which a
" delicate varnish " of hyaloplasm extends, investing the corpuscles and
carrying them along in its flow. Yet the whole system of these
remarkable pseudopodia can be rapidly withdrawn into the general mass
when the animal is disturbed. Hieronymus describes a peculiar fibrous
arrangement of the protoplasm even in the encysted state, which may be
in relation with the peculiar characters of the extended filaments (Fig. 1, c.
Note the linear arrangement of the oat-shaped corpuscles).
Contractile vacuoles abound in the extended protoplasmic body.
Their period probably varies with its activity. In 0. montana Penard
finds it to be very slow.
In the active condition C'hlamydomyxa is able to engulf and digest
algae, desmids, Peridinidae, etc., and outlying masses of protoplasm may
be seen (Fig. 3 (2)) accumulated about such food-bodies.
The accounts of the active phase of 0. montana agree, on the whole,
with Archer's observations of G. labyrinthuloidcs, except that in the
former species the protoplasm, on emerging, completely quits the old cyst-
wall and lies free in the water as a mass of constantly changing shape.
It may be more or less spherical or drawn out into a ribbon, attaining a
length of 300 p, (Penard). A definite hyaline ectoplasm is also present.
(Cp. the figures of this species given by Lankester, Q.J.M.S.
vol. xxxix. Plates xiv. and xv.) In it, moreover, the yellow colouring
matter of the chromatophores usually predominates over the green.
According to most observers, the free state of the organism would
appear to end, after lasting at least " several hours," by the withdrawal of
the extended protoplasm and the re-encystment of the whole animal.
Hieronymus differs considerably from other observers in his account of
the free state. He has also seen the contents emerge from a cyst of
C. labyrinthuloides, assume an irregular amoeboid form, and ingest food
"auf thierische Weise" ; but it is remarkable that he has never, during
the twelve years over which his observations have extended, seen the long
filamentary pseudopodia protruded in the manner which has, in both
species, attracted attention. The nearest approach to such filaments
which he has seen were those of a small specimen suspended free in the
278 APPENDIX
water and emitting long pseudopodia on all sides (3 ; Plate ii. Fig. 25).
After ingesting food the animals were found by Hieronymus to encyst on
the surface of plants, and he states that division of the nuclei follows the
encystment. But in the majority of cases a different process was
observed to follow the emergence from the encysted state. The proto-
plasm puts out short pseudopodia and divides up forthwith, by successive
repartition or by simultaneous division, into small uninucleate amoebae,
the products of division being equal in number to the nuclei contained
in the original cyst. The division into the ultimate products is usually
complete in a few minutes from the emergence of the protoplasm. The
small amoebae so found may creep about and ingest small algae or
bacteria before passing into the encysted form. While this is the usual
course, Hieronymus describes cases in which the process of division ceased
after one or two partitions had occurred, and was followed by a stage of
feeding and subsequent encystment. Further evidence of such cases
would be desirable, and it seems possible that two separate phases of the
life-history may have been here confused ; but it is clear that the fission
of the multinucleate body into uninucleate products represents a phase of
reproduction comparable with that which occurs in many other protozoan
life-histories, and of which we had no previous evidence in Chlamydomyxa.
Spore-Formation. — The process of spore-formation has been most fully
observed by Penard in G. montana,1 but stages of it have been seen by
Archer and Hieronymus in C. labyrinthuloides. The contents of an
encysted form are segregated by simultaneous fission into a number
(20 to 40) of equal (Fig. 2, a) (? sometimes only sub-equal (Fig. 2, 6))
divisions. These are at first continuous with their neighbours by proto-
plasmic strands (3 ; Plate i. Fig. 7), but later they separate into bodies
which become spherical and each secretes a cellulose wall. They are
liberated by the opening of the cyst (in a manner not observed). Penard
finds that these secondary cysts, or spores (Fig. 2, c), as we may call them,
measure in G. montana 18 [L in diameter, and that each contains two
nuclei lying opposite one another in a meridian of the sphere.2 In some
cases the contents of the spores were found to have emerged as naked
masses of protoplasm, containing the chromatophores and refracting
corpuscles characteristic of the species. Each acquired a flagellum (or two
flagella ?) about equal to the body in length (Fig. 2, d), and for some
moments ("pour quelques instants") was actively motile. Some of these
flagellate bodies appeared to possess one nucleus, others two or even
three, and there was an indication of their fusion in pairs (" lorsque les
petits flagellates viennent & se rencontrer, ils peuvent se fusionner en un
seul," p. 331). Some continued to show a slow movement for twenty-
four hours, but ultimately they died under the cover-slip.
It would be premature at present to make any dogmatic statement as
1 It was only for a few days that Penard succeeded in observing this stage in the
life-history. It occurred in March, in the neighbourhood of Geneva.
2 Penard's account of the subsequent history of these bodies is of great interest,
but, owing to the sparseness of his rnaterial and the rapidity of some of the events,
he was unfortunately not able to observe the stages with precision. With this
reserve, an outline of his results is here given.
APPENDIX
279
to the course of the life-history of Chlamydomyxa. The observations
of Penard suggest that the flagellulate bodies hatching from the spores
are gametes, which proceed to conjugate with one another, though the
existence of two nuclei in the spores requires explanation. If this is the
case, we have, as in Trichospliaerium and many other Protozoa, a life-cycle
in which a sexual phase recurs in a series of generations reproducing by
fission.
With regard to the affinities of Chlamydomyxa, we have seen that the
resemblance to Labyrinthula turns out to be in part at least misleading.
ch-
FIG. 2.
CMa»rt >/<'"»>•/"'. a. Early stage of spore-formation in C. montana. The contents of a cyst
have become divided up into young spores ; b, a cyst of C. labyrinthuloides, with mature spores,
x 200 ; c, a single spore of C. montana, showing two nuclei ; d, flagellate body hatched from
a spore. ('<, <•, ami il after Penard ; 6 after Archer.)
We are unable to agree with Penard that it is allied to the Mycetozoa,
for there is no evidence that the protoplasmic masses are plasmodia in
the true sense of the term. It appears that the most satisfactory position
to assign to it, in the present preliminary stage of our knowledge of life-
liistories, is as an isolated rhizopod, containing chromatophores, which
may be provisionally placed in the neighbourhood of the freshwater forms
with filose pseudopodia which, in this work, are included in the Order
Gromiidea of the Foraminifera (see p. 283). In the possession of many
nuclei it resembles Trichosphaerium among the Rhizopoda Lobosa.
LITERATURE.
1. Archer, W. On Chlamydomyxa labyrinthuloides, nov. gen. et sp., a New
Freshwater Sarcodic Organism. Quart. Journ. Micr. Sci. N.S. xv.
(1875), p. 107.
280 APPENDIX
2. Gcddes, P. Observations on the Resting State of Chlamydomyxa laby-
rinthuloides, Archer. Ibid. xxii. (1882), p. 30.
3. Hieronymus, G. Zur Kenntniss von Chlamydomyxa labyrinthuloides,
Archer. Hedvvigia, Bd. xxxvii. (1898), p. 1.
4. Jenkinson, J. W, Abstract and Review of the above paper by Hieronyimis.
Quart. Journ. Micr. Sci. N.S. xlii. (1899), p. 89.
5. Lankester, E. Ray. Chlamydomyxa monta'iia, n. sp., one of the Protozoa
Gyranomyxa. Quart. Journ. Micr. Sci. xxxix. (1896), p. 233.
6. Penard, E. Etude sur la Chlamydomyxa montana. Arch. f. Protistenkunde,
Bd. iv. Heft 2 (1904), p. 296.
LABYRINTHULA.
The members of this genus consist of associations of nucleated proto-
plasmic units ("amoebae" of Zopf, "spindles" of Cienkowski) joined in
a network of sparingly branched and anastomosing threads. They are
met with in a diffuse or aggregated condition, and, as the result of
drying, the units pass into a condition of encystment, from which they
hatch out in the form of the amoeboid units.
Two marine species were described in 1867 by Cienkowski (1), who
found them on algae growing on wooden piles in the harbour of Odessa :
L. vitellina, Cienk., in which the protoplasmic units contain a yellow or
orange colouring matter ; and L. macrocystis, Cienk., in which the units
are larger and colourless. Zopf (4) in 1892 described a freshwater
form very similar to L. macrocystis, parasitic on the alga Vaucheria.
He named it L. cienkowskii, Zopf.
In the marine forms the system of connecting threads appears to have
a remarkably firm and rigid consistency, and Cienkowski describes the
movement of the units along the threads, as though the latter were
peculiarly differentiated structures ; but from Zopf's description of L.
cienkowskii it can hardly be doubted that they are pseudopodial in nature.
Zopf observed them to be slowly protruded from a mass of units, and to
be withdrawn, to move slowly from side to side, and to fuse with their
neighbours. He also describes the passage of food - granules along
them.
The units are without a limiting membrane and contain a single
nucleus, with a nucleolus. When drawn out in the expanded condition
of the organism they are generally spindle-shaped (Fig. 3 (3)), but they
may present processes in three directions (Fig. 3 (4)). In the aggregated
condition the units are round or oval. Those of L. macrocystis measure
18-25 fj, in long diameter, those of L. vitellina and L. cienkowskii about
1 2 /*. The protoplasm is granular, and in L. vitellina contains a yellow
or orange fatty pigment, soluble in alcohol. A small vacuole is usually
present, but it is not stated that it is contractile.
The whole organism, or a part of it, is often found in the aggregated
condition (Fig. 3 (5)), and the marine species may thus form masses
measuring a millimetre or so in diameter. The main aggregate is
described by Cienkowski as invested, in L. vitellina, by a " cortical sub-
stance" (neither protoplasmic nor of the nature of cellulose) through
APPENDIX 281
which the filaments are protruded, but this was not seen in the peripheral
aggregates of this species, nor at all in the active condition of the other
species.
Labyrinthula is actively parasitic on the algae which it infests,
breaking down the contents of the cells into a granular mass.
As the result of drying, the organism passes into a condition of
encystment. The units became closely aggregated and each secretes a cyst-
wall, which is double in L. cienkowskii. A firm common envelope may
now be formed (in L. macrocystis, Fig. 3 (5), but not in other species) in
which the encysted units are embedded.
The behaviour of the encysted unit appears to vary in the different
species. In L. cienkowskii Zopf describes and figures the emergence of a
single mass from the cyst. In the other species, Cienkowski found that the
contents divided into four within the cyst (Fig. 3 (6 and 7)). Zopf observed
the protrusion of one or two long pointed pseudopodia, on hatching, and
the final emergence of the protoplasmic mass from the cyst, which was
left empty. From the fact that on one occasion three empty cases were
found with three units in their neighbourhood, and that these were in
connection by their pseudopodia, Zopf concludes that the hatched units
join with one another to start a fresh association.
Zopf regards the association of units of Labyrinthula as representing
a stage in the formation of a plasmodium intermediate between the true
•plasmodium of the Euplasmodida (cf. p. 43), in which there is a complete
fusion between the protoplasmic bodies of the uniting amoebulae, and the
pseudoplasmodium of the Sorophora, in which the amoebulae, aggregating
before spore-formation, come into apposition but maintain their distinct-
ness (p. 60). This intermediate form he would distinguish as a Thread-
-plasmodium (Fadenplasmodium).
The propriety of this view seems far from clear. We are familiar
•with many cases among Protozoa in which an association of individuals,
a. colonial organism, is formed by the successive multiplication of the
units, whose offspring remain in connection by protoplasmic processes
(Colonial Radiolaria, Volvox, Mikrogromio), and the higher animals and
plants are often regarded as such colonial organisms, in modified
forms.
That an increase in the number of units in the associations of Laby-
rinthula occurs by binary fission of the units is abundantly clear. It is
true that it appears probable, from Zopfs observation above quoted, that
a fusion may occur in Labyrinthula (though it was not actually observed)
between the pseudopodia of individuals recently emerged from the
•encysted state ; but a parallel to this process may be found in the
fusion of the protoplasmic masses emerging from the cysts of the
sclerotial condition of the Mycetozoa on revival of activity (cp. p. 50).
There are fair grounds for regarding the fusion of the amoebulae
by which the Mycetozoan plasmodium takes its origin (in the Euplas-
modida) as a part, at any rate the plastogamic part, of a sexual union of
which the final, karyogamic, stage is deferred. It would not be sug-
gested that the fusion after the sclerotial stage is a repetition of this
process in the Mycetozoa, and we may well hesitate, in the present
282
FIG. 3.
APPENDIX 283
fragmentary state of our knowledge of Labyrinthula, to accept the conclu-
sion that the (inferred) fusion between the pseud opodia after encystment
represents this important event in its life-history.
We are therefore inclined to regard Labyrinthula as a colonial
organism of which the units remain in connection by their pseudopodia.
As the result of drying they may pass into the encysted stage, in which
they are isolated from their fellows by the cyst-walls. It appears prob-
able, from Zopfs observation, that, on resuming activity, they may
again unite with their fellows to form a colony. Other stages of the
life-history are at present unknown to us.
With Labyrinthula Zopf associates the genus Diplophrys (Archer),
Cienk. The species named Diplophrys stercorea by Cienkowski (2) is a
colonial organism, with simple thread-like pseudopodia, living on horse-
dung. It can hardly belong to the same genus as Diplophrys Archeri
(Barker), with ramifying pseudopodia and a distinct though membranous
FIG. 3.
2. CMamydomyxa Ifihyrinthuloldes, Archer. The animal in the free state partially emerged
frcnn the many-layercil cyst. A small encysted mass is seen at c between the envelopes of the
latter. At o and elsewhere in the main body of the protoplasm, as well as in outlying portions,
invested food particles are shown. The oat-shaped corpuscles are seen on the stiff extended
filaments, x about 150. (From Lankester, after Archer.) 1 and 3, I.abi/rinthulrt riteltiiw,
C'ienk. 1, a colony crawling upon an alga. The units are partly aggregated, partly extended
on the network of stiff extended pseudopodia. x about 120. 3, part of the network, x about
250. At p and p1 several units have fused into a common mass ; », s, units which have assumed
the spherical shape and are stationary. 4-7, Labyrinthula macrocystis, Cienk. 4, a single unit
giving out three pseudopodia ; n, its nucleus ; x 320. 5, a group of encysted units invested in
a tough secretion, x about 250 ; f> and 7, encysted units the contents of which have divided
into I'our, x about 320. (From Lankester, after Cienkowski.)
test. Both forms, together with Labyrinthula and Chlamydomyxa, may
provisionally be regarded as related in one direction to outlying members
of the Gromiidea, here included in the Foraminifera, and in others to the
Heliozoa and the Proteomyxa. The grounds for regarding the two latter
genera as especially related have vanished in the light of fuller knowledge.
LITERATURE.
1. Cienkowski. Ueber den Ban u. Entwickelung der Labyrinthnleen. Arch.
f. inikr. Anat. Bd. iii. (1867), p. 274.
2. Ueber einige Rhizopoden und vevwandten Organismen. Ibid. Bd.
xii. (1876), p. 44.
3. Lankester, E. II. Article "Protozoa" (Class Labyrinthulidae). Encyclo-
paedia Britannica, 1891.
4. Zopf, jr. Zur Kenntniss d. Labyrintlmleen, eine Fain. d. Mycetozoen.
Beitr. zur Phys. u. Morphologic niederer Organismen, Heft 2 (1892),
p. 36, and Heft 4 (1894), p. 60. Leipzig.
APPENDIX B.
THE XENOPHYOPHORIDAE, F. E. SCHULTZE.
THE organisms that are now included in this family were formerly
regarded as Porifera, and several of them were described in 1889 by
Haeckel in the " Challenger " volume xxiii., on the deep-sea Keratosa.1 In
the year 1892, Goes (1) described "a peculiar arenaceous Foraminifer
from the American tropical Pacific" as Neusina agassizii, which Hanitsch
in the following year proved to be identical with Haeckel's deep-sea
Keratose sponge Stannophyllum zonarium. We are indebted to Schultze
(2) for an exhaustive treatise on these genera, and the more definite
proof that they are not sponges, but probably related to the Foraminifera.
They are spherical or disc-shaped (Psammetta), fan-shaped (Stannojihyllum,
Fig. 1), or dendritic (Stannoma) bodies of about 20 mm., more or less, in
diameter or height, and of a fibrous, spongy
texture. They have been found at depths
of from 550 fathoms to 3000 fathoms in
the Indian, Atlantic, and Pacific Oceans.
They consist of a plexus of thin-walled
tubes, some of which open on the surface,
and the meshes of the plexus contain a
large number of foreign bodies (xenophya),
such as the shells of Radiolaria, Foramin-
ifera, spicules of sponges, and grains of sand.
The tubes contain either a large number
of dark olive-brown bodies, the sterkomata,
or else a multinucleated plasmodium con-
taining numerous clear solid bodies called
the granellae. The sterkomata are remark-
ably resistant to strong acids and alkalis, and they often contain fragments
of radiolarian and foraminiferan shells. They are regarded by Schultze as
of the nature of the faecal balls such 'as are found in other Foraminifera
(Gromia, Saccamina, etc.). The tubes containing the sterkomata (Ster-
komarium) are probably continuous with the tubes containing the granellae
(granella'rium). The granellae are about 1-2 /x in diameter, and are mainly
composed of barium sulphate. The nuclei which occur in the plas-
modium of the granellariurn are very numerous, and usually scattered
FIG. i. "
Stannophyllum zonariiim, Haeck.
x §. (After Schultze.)
1 Cf. A Treatise on Zoology, Part II., 1900, p. 154.
284
APPENDIX
285
irregularly among the granellae. In some cases (Fig. 3) aggregations of
nuclei with an investing portion* of the protoplasm become separated from
-r.
FIG. 2.
Section through the middle layer of J'srnnminn glubigfrina, Haeckel, showing the plexus of
tubes containing a multinucleated plasmodium. At o, a are seen some of the foreign bodies
(xenophya) associated with the organism ; s, s, tubes of the sterkoinarium ; g, g, tubes of the
granellarium. (After Schultze.)
the plasmodium, and these break up into swarm-spores, which Schultze
regards as possibly gametes.
In the family Stannomidae there are found, in addition to the tubes-
already mentioned, many fine skeletal fibres called the " linellae," which
form a plexus in the interstices of the other
parts of the organisms.
In the absence of any information con-
cerning the early stages of development, or
of the character of the pseudopodia in the
members of this family, it is difficult to
assign to them their proper systematic
position. The Foraminiferan genus Poly-
trema and some of its allies liave the same
habit of incorporating into their substances
sponge spicules and other foreign bodies, and
they also lose at an early stage of develop-
ment the external evidence of the chambered
condition, and assume dendritic forms.
Moreover, in Polytrema we find, in addition
to the calcareous skeleton, a system of are breaking up into spores,
horny or chitinous tubes which have some
resemblance to the tubes of the Xenophyophoridae. In the absence of a
calcareous "skeleton the family differs from all the higher and more
differentiated families of Foraminifera, but nevertheless the affinities of
the family are greater \vith this class than with any other Protozoa.
FIG. 3.
Diagram of the granellar region-
of a Xenophyophorid, showing the
nuclei, n, n, and granellae, g, g, of
286 APPENDIX
The Xenophyoplioridae may therefore provisionally be placed in the
Class Foraminifera.
FAMILY XENOPHYOPHORIDAE.
Sub-Family PSAMMIXIDAH-. Without linellae. Not flexible. Genera
— Psammetta, F. E. S. ; Psammina, Haeck. ; Cerelasma, Haeck. ; Holo-
psamma, Carter ; Psammopemma, Marshall.
Sub-Family STANNOMIDA. With linellae. Body flexible. Genera —
Stannoma, Haeck.; Stannophyllum, Haeck. (Fig. 1); Stannarium, Haeck.
LITERATURE.
1. Goes. Ncusina agassizi. Bull. Mus. Harvard, xxiii., 1892, p. 19f«.
2. Schultze, F. E. Die Xenophyophoren. " Valdivia" ExpeJ. xi., 1905.
3. "Siboga" Exped. Mon. iv. bis, 1906.
4. Bull. Mus. Harvard, li. 6, 1907.
INDEX
Figures given in thick type refer to the systematic position.
f. refers to an illustration.
Abyla pentagona, 249
Acautharia, 94, 102, 106,
113, 145
Acanthochiasma, 146 ; A.
cruciala, 146 ; A. fusi-
forme, 145 ; A. krohnii,
145 ; A. rubescens, 143
Acanthochiasmidae, 146
Acanthocystis, 21, 24, 28,
29, 34, 119 ; A.aculeata,
16/., 27/., 28/. ; A.
italica, 34 ; A . marina,
34 ; A . simplex, 34 ; A .
spinifera, 23 ; A. tnr-
facea, 23
Acanthodinium, 187
Acanthometra sicula, 143
Acanthometrida, 113, 145
Acanthometron, 123, 146 ;
A. bifidum, 137/. ; A.
Claparedei,l05f. ; A. pel-
lucidum, 118/., 146
Acantfwnia, 146 ; A. ligur-
ina, 146 ; A. miilleri,
146 ; A. tetracopa, 127,
128/., 132/.
A cant/ion id ium, 146 ; ^4.
echinoides, 146 ; .4. ^«Z-
lidum, 146
Acaiithoniidae, 146
Acanthophractida, 146
Acrasiae, 39
. lr.V".v/,9, 65
Actineliida, 145
Actinelius, 145 ; .1. ^'/'-
pureus, 145
Actinolophus, 15, 23, 28,
33
Actinomma, 127 ; .4. as&r-
acanthion, 103/.
Actinomonas, 165
Actinophrys, 18, 19, 21,
29, 30, 33, 39 ; vl. soZ,
15, 16/., 21 f.
Actinosphaeridium, 33
Actinosphaerium, 21, 22,
23, 25, 26/., 29, 30, 32,
33,48,86, 87; .1. arach-
noideum, 23 ; A. Eich-
horni, 14/., 22 ; A. im-
patiens, 10 f.
Actissa, 104, 110, 144
Aethalia, 56
akaryote, 1, 2
Alwisia, 63
Amaurochaetaceae, 63
Amaurochaete, 63 ; -I. ati-<>,
41
Amaurochaetineae, 62
Amaurosporales, 61
Amoeba, 2, 69, 77 ; A.
binucleata, 73, 79 ; A.
buccalis, 84 ; ^1. crystal-
ligera, 73, 78 ; ^1. dof-
leini, 71 ; ^1. fluida,
78; ^1. guttula, 78/.,79;
yl. hyalina, 73 ; .4. Aar-
tulisi, 84 ; ^4. Umax, 69,
70, 73, 77/., 79, 83 ; .4.
pilosa, 68 ; .4. proteus,
73, 74/., 77, 78/., 79 ;
.4. radiosa, 79 ; -4. rote-
<on'a, 195 ; ^4. terricola,
68 ; .4. urogenitalis, 84 ;
^4. verrucosa, 78f.; A.
villosa, 79 ; .4. vorax,
78 /.
yliftoeda (marine forms), 78
Amoebophrya, 105 /., 123
Amoebulae in Heliozoa, 29 ;
in Lobosa, 76, 77 ; in
Mycetozoa, 42, 59 ; in
Proteomyxa, 4, 5
A iiijiliiiliniuui, 183
Amphilonche, 123, 146 ;
.1. atlantica, 137/. ; .4.
belonoides, 146 ; Jl. ww-s-
sanensis, 103/.
287
Amphilouchidae, 146
Amphinwiias, 168
Amphisolenia, 187 ; -<4.
globifera, 184/.
Amphizonella, 80
Ancyromonas, 165
Anemineae, 55, 63
Anisonema, 171
Ankistrodesmus, 179
Anopheles, 240 ; ^4. maculi-
pennis, 248
Antlwphysa, 158, 161, 167 ;
-4. vegetans, 178 f.
Apheiidinm, 3, 10, 11 ; ^4.
lacerans, 11
Aphrothoraca, 33
Apiocystis, 180
Apstein, 192
Arachnula, 9
.4rce/fo, 68, 71, 72, 85/., 86
87, 90 ; A.vulffaris,90f.
Arcellidae, 85, 90
Archer, 22, 274, 277, 279
Arcyria, 52 n., 55, 64, 65 ;
.4. incarnata, 56 f. ; ^4.
punicea, 56f.
Arcyriaceae, 44, 55, 64
Ascoglena, 157, 171
Astasia, 171 ; .4. <e»ww^
166/.
Astasiina, 171
Astrocapso, 146 ; A. coro-
nata, 146; ^4. tritonis,I46
* 1 strodiscv his, 33; .4 .
radians, 16 /.
Astrolophidae, 145
Astrolophus, 145
Astrosestrum acanthastrum,
145
! Atliene noctua, 202, 233
Athias, 254, 269
Atlanticella, 109, 150; ^4.
craspedota, 149
Atractonema, 171
288
INDEX
Aulacantha, 113, 119, 121 ;
Brass, 13
Chactomorpha crassa, 10
A. scolymantha, 111 /.,
Brauer, 31, 32, 35, 245
Chalaro'thoraca, 23, 34
112, 117, 121, 124,
Braun, 13
Challengeridae, 113, 148
125 /., 136, 147
Brefeldia, 63
Challengeron armatum, 148
Aulacanthidae, 147
Breinl, 206 n.
/. ; (J. balfouri, 148 ; C.
A ulactin ium actinastrum,
Bruce, 195, 199, 269
golfense, 148 ; C. johan-
109 /.
Brumpt, 196, 198, 204,
nis, 148 ; C. trioden,
Aulodendron boreale, 148
226, 228, 269
148
A idographiftfurcellata, 148 ;
de Bruyue, 4, 13
Chilomonas, 176
A. tetrancistm, 148 ; A.
Buffard, 205, 269
Chironomus plumosus, 245
zetesios, 148
Burstdla, 3> 11, 12, 40, 60
Chlamydococcus, 180
Aulokleptcs Jlosculus, 110,
Biitschli, 5, 6 n., 13, 35,
Clilamydomonadina, 180
135 /.
39, 66, 70, 91, 115, 131,
Chlamydomonas, 22, 180 ;
Auloscena vertidUatus, 112
151, 190
C. pulvisculus, 166/.
/., 148
Chlamydomyxa, 39, 274 ;
A ulosphaera elegantissima,
(J<«H<iiii nii'fii, 148
C. labyrinthuloides, 274,
105 /. ; A.fiexuosa, 148
Calcariueae, 49, 55, 62
275 /., 279 /., 282 / ;
Aulotractus fusidus, 148
Calkins, G. N., 13, 20, 79,
< '. Montana, 274, 277,
Audcularia, 49
91, 219
278, 279 /.
Awerinzew, 35, 91
Calouemineae, 64
Chlamydophora, 33
Calymma, 95
L'lilnrinJ.esmus, 158
Badhamia, 52 n., 55, 62 ;
Calyptrosphaera, 176 ; C.
Chlorogonium, 180 ; C.
B.panicea, 42/., 52 /. ;
oblonga, 175/.
I'uchlorum, 166 /.
B. utricularis, 44 /., 46
Campascus, 90
Chloromonadina, 174
/., 48, 49, 50/., 51 /.
Camptonema, 33
CJwanocystis, 35
Barbagallo, B., 92
Cannocapsa, 146 ; C. oscu-
Choanortagellata, 176
cle Bary, 38, 61, 66
lata, 146
Chodat, 22
Basidiomycetes, 40
Cannosphaera antarctica,
Chodatella, 179
Bathybius, 12
148
Chondrioderma, 53, 54, 55,
Belonaspidae, 146
capillitium, 52, 55
62 ; (7. testaceum, 54 f.
Beneden, E. van, 2, 13
Carpocanium diadema, 105
Chondropus virulis, 33
Berg, 195
/, 147
Christophers, 257, 272
Bicosoeca, 161, 168 ; B.
Carteria, 178, 180
Chromatella, 80
socialis, 158, 168
Casagrandi, Q., 92
Chromidia, in Heliozoa, 18 ;
Bikoecina, 168
Cash, J., 13, 78
in Lobosa, 71 ; in Pro-
Billet, 226, 269
Castauellidae, 150
teomyxa, 1 ; in Radio-
Biomyxa, 2, 3, 9 ; B. cometa,
Castanidium apsteini, 150
laria, 121
9 ; B. <cagans, 9
Castellani, A., 92, 196,
Chromomonadidea, 173
Bionomics in Tlialassicolla,
269
Chromulina, 157, 174; C.
96
Caulerpaj'12
•rosanojft, 173
Blackmau, 180, 192
Central capsule in Eadio-
Chrysamoeba, 173, 174
Blepharisma, 22
laria, 114
Ohrysococcus, 161, 174
Blepharocysta, 186, 187
Centralkorn, 28
Chrysomonadina, 174 ; C.
Boderia, 10 ; B. turneri,
Centrochlamys, 80
loricata, 174 ; C. mem-
11 /
Centropyxis, 71, 75, 76, 77,
branata, 176 ; C. nuda,
Bodo, 157,' 161, 162, 163,
86, 87, 88, 89
174
167, 246 ; B. caudatus,
CepJuilothamnion, 161, 167
Chrysopijxis, 174
166 /. ; B. lacertae, 211,
Ceratiidae, 187
Cienkowski, on Chlamy-
247; B. lens, 178/.
Ceratiomyxa, 40, 57, 59,
-. domyxa, 280 ; on Helio-
Bodonina, 167
64, 66 ; C. mucida, 58 f.
zoa, 29, 35 ; on Labyrin-
Borgert, 110, 119, 124,
Ceratiomyxaceae, 64
thula, 283 ; on Mastigo-
152
Ceratium, 158, 186, 187 ;
phora, 190 ; on Myceto-
Botryocampe inflata, 147
C. hirundinella, 183 n. ;
zoa, 38, 43, 61, 66 ; on
Botryococcus, 179
C. tripos, 186 /.
Protozoa, 4, 10 /., 13 ;
Botryoidea, 147
Ceratocorys horrida, 184/.,
on Racliolaria, 97, 152
Bott, 91
187
Cienkmvskia, Heliozoa, 34 ;
Bourne, 81, 91
Oercobodo, 166 ; C. crassi-
Mycetozoa, 62
Box boops, 247
cauda, 166/.
Ciliophrys, 4, 8, 10 /. ; C.
Bradford, 206 n., 269
Cercomonas, 165
infusionum, 10 f.
Brandt, 96, 97, 104, 106,
Ccrelasma, 286
Cimex rotundatus, 259
110, 112, 127, 129, 152
Certes, 273
Circoporidae, 150
INDEX
289
Circoporus sexfuscin i's,
112, 117
Cistidium inenne, 105 /.
Cladomonas, 168
Cladophora, 11
( 'l«i<l * I*-,: ,i iuin tricolpium,
147
Cladothrix, 72 f. ; (7. ^>eZo-
myxae, 81
Classification of Haemofla-
gellates, 248 ; of Helio-
zoa, 33 ; of Lobosa, —
Gymnamoebida, 77 ;
Thecamoebida, 84 ; of
Mastigophora, 154 ; of
Myceto/.oa, 61 ; of Pro-
tuoniyxa, 6 ; of Radio-
laria, 144 ; of Xenophyo-
phoridae, 286
Clastoderma, 63
Clathrocydas craapedota,
147
Clathrulina, 25, 29, 34 ;
C. elegans, 16/., 23
Closterium, 32
Clypevlina, 90
Coccolithoplioriuae, 176
Coccolithqpora, 176 ; C'.
lejttopora, 175 f.
coccolitlis, 174
Cocliliopodiidae, 84, 85, 88
Cochliopodium, 71, 80, 88 ;
C. actinophorum, 88 ;
C. diijitntuni, 88 ; C.
pellucidum, S8/.
Cochlodinium, 185
Codonoeca, 167
Codosiga, 177 ; C. um-
bel la ta, 178/.
Coelodeudridae, 150
Cododendron ramosissi-
mum, 150 ; C. gracilli-
minn, 105 /.
Coelographidae, 150
Coelomoiuts, 174
murrayanum ,
151 /. : ''. trtkmit, 151
Coelothamn us davidoffi,
151 /.
Coenobia, 181
Colacium, 171
Coleochaeta, 11
Collodaria, 113
<'i>l/,,ilict)/on, 169
Collosphaera, 111 w., 121,
12:; ; <_'. )iii.r/,-i/i, 140/. ;
C. murrayaitc, 145
Collospbaeridae, 104, 145
Collozoum, 98, 139 /. ; C.
fill rum, 138; C. inenne,
103 /., 126 /., 138,
141/., 142 /., 145; C.
.pelagicum, 145 ; C'.
radiosum, 138
Colpodella, 3, 5, 10, 11 ;
(7. pugnax, 10/.
Colponema, 168
columella, 53
Comatricha, 52 n. , 55,
62
Concharidae, 150
Contractile vacuoles in
Heliozoa, 18 ; in Lobosa,
85; in Mastigophora,
160 ; iu Mycetozoa, 49 ;
in Proteomyxa, 3 ; in
Radiolaria, absent in
Thalassicolla, 97
Convoluta, 22 ; O. ros-
co/ensis, 129, 180
Copromonas, 160 /., 161.
162, 163, 171, 172, 177 ;
C. subtilis, 172
Copromyxa, 65 ; C. protect,
60 /.
Cornutella dathrata, 147
Cornuvia, 64
Cortina typus, 107 /.
Cwtiniscus typicus, 146
Corycia, 80, 89
Costia, 157, 168 ; C.
necatrix, 169
Craig, C. F., 92
Craspedomonadiua, 177 ; C.
loricata, 177
Craspedotdla, 190
Craterium, 44, 54, 55, 62 ;
C. pedunculatum, 54 /.
Crawley, 23, 35
(.'rilimria, 54, 63
L'rithidiu, 228, 240, 241 /. ;
C. campamdata, 245 ;
C. fasciculate, 242, 248
Gryptoglena, 171
Cryptoruonadina, 176
('-in nbalus kochii, 249
Cucurbitdla, 89
I'ipiens, 202 f., 233,
243
Cyathomonas, 176
Cydonexis annularis, 158
Oycloptems lumpus, 247
Cylindyospermum, 11
Cyphoderia, 90
Cyrtocalpis obliqva, 147
Cyrtoidea, 114, 147
Cystoflagellata, 188
Cytodadus spinosus, 115
/, 1*4
, 179
Dactylosjthaera, 79 ; /).
polypodies 72 /., 73 ;
/>. radiosa, 78/., 79
l)n in <> ida reevesii, 254
Bangeard, P. A., 3, 13
Danilewsky, 195, 255, 269
Delage, 39
Delap, 153
Dendromonas, 158
Desmothoraca, 23, 25, 34
Diachaea, 62 ; X>. elegans,
45
Dianema, 64
Diaphorodon, 90
Diatoms, 11
Dictydiaethalium, 63
Dictydium, 54, 63 ; Z>.
umbil ica him, 55 /.
Dictyocephahis ocellatvs,
147
Dictyomyxa, 10
Dictyophimus clevei, 147
Didyopodium, 127
Dictyosteliaceae, 60, 65
Bictyostdium, 60, 65
Dictyota, 114
Didymiaceae, 56, 62
Didymium, 44, 55, 56, 62 ;
Z). di/orme, 43 /. ; Z>.
effusuflf, 57 /.
Difflugia, 71 /, 72, 84,
85, 86, 89 ; I>. globosa,
86; D. pyriformis, 89 /. ;
Z). urceolata, 86, 87, 88
Difflugiidae, 89
Dimastigamoeba, 165
Dimorpha, 164, 165
Dinamoeba, 68, 80
Dinema, 171
Dinobryon, 157, 158, 161,
173, 174 ; Z>. sertularia,
1-65 /.
Dinoflagellata, 182
Dinophysidae, 187
Diiiophysis, 187
Diplocouidae, 146
Diploconus, 146
Diplomita, 168
Diplophrys, 283 ; Z).
Archeri, 283 ; Z». ster-
corea, 283 .
Diplophysalis, 4, 5, 8
Diplosiga, 177
Discoidea, 145
Discorbina, 112
DiscospJiaera, 176 ; Z>.
tabifer, 175 f.
Distephanits speculum, 191
Distigma, 171
Distomatina, 169
Dobell, 160 «., 163, 172,
192
19
290
INDEX
Doflein, F., 13
"Fingersand Toes" disease,
Gymnosphaera, 23. 33
Donovan, 256, 272
3
Gyromonas, 169
Dopter, 82, 92
Flagellata (Mastigophora),
Dorataspidae, 146
155
Hacker, 113, 117, 122, 153
Dorataspis, 127
flagellulae, 4, 5, 29
Haeckel, 1, 13, 104, 110,
Dourine, 196, 197, 206
Flowers of Tan, 47
119, 127, 131, 152, 284
Dreyer, 116, 131, 152
Forde, 196
Ilaeckelina, 8
Dum-dum fever, 256
Fowler, 113, 152
Haematococcus, 180 ; //.
Durham, H., 240
Franya, 254, 269
palustris, 166 f.
Dutton, 196, 255, 269
Freuzel, 91
Haemaiomonas, 250
Frenzdina, 90
Haematopinus, 198, 203
Echinomma leptodermum,
Fuligo, 50, 55, 56, 57, 62,
Haematopota. 242, 258
145
65 ; F. septica, 40 /.,
Haemoflagellates, 193 ; bio-
Echinostelium, 63
47, 57 /.
logical considerations,
Ectobiella, 3/., 12
217 ; classification, 248 ;
Ehrenberg, 17, 112, 151,
comparative morphology,
155
Gamble, 22, 35, 99, 110,
207 ; evolution ami
Eikenia, 80
129, 153, 180, 192
phylogeuy, 240 ; habitat,
Elaeorhanis, 14, 22, 23, 34
Gametocytes, 25
196 ; historical, 194 ;
Elaster, 35
Gasteromycetes, 40
Leishman - Donovan -
Elpatiewsky, W., 93 n.
Gazdletta, 149
Wright bodies, 255 : life-
Enchylema, 69
Geddes, 274, 280
cycle, 226 ; list of hosts,
Endamoeba, 68, 71, 82 ;
Giemsa, 196
162 ; literature, 268 ;
E. blattae, 74 /., 83,
Glaeocystis, 180
multiplication, 222
84 /. ; E. coli, 73, 74,
Glenodiniidae, 186
Halistemm a tergestin u m ,
75, 82 /. ; E. histolytica,
Glenodinium cinctum, 184
249
75, 82, 83/. ; E. iurai,
/. ; G. pulvisculus, 187
Halteridimn, 236, 248
83 ; E. undulans, 83
Gloidium, 2, 3, 5, 6/.
Hanburies, 3
Endosporeae, 40, 57
Glossina, 200 ; G. fusca,
Hauna, 270
Endyonema, 2, 3, 5, 12
199 n., 200, 201; G.
Haplococcus, 3, 12
Enerthenema, 62
morsitans, 199; G.patti-
Harper, 65
Engler, 191
dipes, 199 n. ; G. pal-
Hartmaun, 159 «., 192
Enteridium, 63
palis, 199, 200, 231 ; G.
Hartog, E., 13, 68
Enteromyxa, 3, 12
tachiiioides, 200
Hedriocystis, 23. 34
Entocanmda hirsuta, 148
Gluge, 195
Hdcosoma tropicum, 259
Entosiphon, 171
Goebel, 13
Heleopera, 85, 90
Esox lucius, 255
Goes, 284, 286
Heliophrys, 33
Estrdla, 33
Goldschmidt, R., 91, 163,
Hdiosphaera inermis,103f.
EucecrypJialus, 128
164, 192
Heliozoa, 14 ; classification,
Eucoronis nephrospyris, 146
GolenJdnia, 33, 179
33 ; food, 18 ; karyo-
Eucyrtidium, 127 ; E.
Gomphonema, 7
kinesis, 25 ; literature,
cranioides, 108 f.
Gonium, 158, 182 ; G.
35 ; nucleus, 25 ; re-
Eudorina, 181, 182
pectorale, 158, 166 /.
production, 28 ; skeletal
Euglena, 157, 161, 171 ;
Gonyaulax, 187
investments, 23 ; struc-
E. acus, 166 /. ; E,
Grassia, 164
ture, 15
gracilis, 172 ; E. mridis,
Gray, 199, 200, 203, 230,
Hemiclepsis. 227
166/., 172
269
Hemidinium, 183, 184
Englenina, 171
Greeff, 22, 24
Hemitrichia, 55, 64 ; H.
Euglenoidea, 170
Greenwood, 49, 66
chrysospora, 56 f.
Euglenopsis, 171
Greig, 199
Herouard, 39
Eu-mycetozoa, 39
Grenadier, 23, 28, 35
Herpetomonas, 157, 161,
Euplasmodida, 39, 40, 43
Gruber, 78
226, 240, 241, 250 ; //.
Euphysetta natlwrsti, 148
Gruby, 269
biitschlii, 245 n. ; 11.
Eutreptia, 171
Gubernaculum, 159, 194
bombycis, 245 ; H. culicif,
Evans, G., 195
Quttulina, 60, 65
242 ; H. gracilis, 241,-
Exoeporeae, 40, 57, 64
Guttuliuaceae, 65
245 ; //. jaculum, 241 ;
Exuviaella, 185 ; E.
Gynmamoebida, 77
H. lewisi, 195 ; //.
marina, 127
Gymnococcus, 3, 5, 11
minuta, 241 ; H. mnscae-
jSfymnodinium, 183, 184
domesticae, 232, 241 ;
Famintzin, 58, 66, 98, 129,
Gymnophrys, 2, 3, 9 ; G.
H. sarcophagae, 245 ; H.
152
cometa, 10/.
subulate, 241 /.
INDEX
291
Hertwig, on Heliozoa, 15,
Jalin, 42, 65, 66
Lebailly, 270
24 /., 25, 27, 31, 32,
James, 272
Lecquereusia, 89 ; L.
35 ; on Lobosa, 75, 87,
Jenkinson, 280
spiralis, 89 /.
91 ; on Radiolaria, 114,
Jennings, 70, 91
Leeuwenhoek, 155
115, 123, 127, 152
Johnstone, 129, 153
Leger, 196, 198, 215,
Heterodevmaeeae, 63
Jiirgeiis, 92
217 n., 226, 229, 230,
', 187
234, 240, 242, 245, 247,
Heteromastigina, 248
Kala-Azar, 256
257 «., 258, 270, 271
Heteromastigoda, 167
Karawiew, 123, 152
Leidy, 23
heteromastigote, 158
Karyokinesis, in Actino-
Leishman, 196, 257, 272
Heterophrys, 21, 22, 28,
sphaerium,25 ; in Lobosa,
Leishmania donovani, 232,
34, 16-t ; //. Fockei, 24
73 ; in Mastigophora,
256, 257 f. ; L. tropica,
/. ; //. myriopwia, 16/.,
161 (Noctiluca, 190) ;
257 f., 259
23
in Mycetozoa, 46/., 48.
Leishman- Donovan- Wright
Hexacon t ium entha can-
65 ; in Proteomyxa, 2 ;
bodies, 255
tli in in, 145; //. pachy-
in Radiolaria, 126 ; in a
Leocarjivs, 62
derm itm, 145
Trvpanosome, 213
Lcpidoderma, 56, 62 ; L.
Hexacoiixs, 146
Keeble, 22, 35, 99, 110,
tigrinmim, 54 f.
Hexadon's ICH-CHU*. 145
129, 153, 180, 192
Lepocindis, 171
Hexalaspidae, 146
Kempner, 198, 272
Leptodiscns, 190
Hexalonche philosophical,-
Kent, 195
Leptomonas, 165
145
Ken ten, 172
Leptophrys, 2, 3, 4 /"., 5, 8
ins, 157, 162, 169 ;
Keysselitz, 198, 229, 270
Lesage, 82, 92
//. !,(ftatus, 178 /. ; H.
Klebahn, 35
Lesser, 15, 24 /.
muris, 170
Klebs, 127, 153, 161, 165,
Lethodiscus microporus,
Hexaplagia arctica, 147
172
145
Hickson, 162, 192, 194 n.
Koch, 200, 203, 251 n.,
Lenciscus erythvoplithal-
Hieronymns, 274, 276, 280
270
mxs, 249
Hinde, 153
Kofoid, 182, 187, 192
Lewis, 195
liip-paraplegia, 206
Kranzlin, 65
Ley den, 91
Hippobosca rufipes, 1 99 /.
Krohn, 188 n.
Leydenia, 84 ; L. gemmi-
Hirmidium, 158, 177
Krukenberg, 50, 66
para, 84
Histioneis, 188 ; //. cym-
Krzysztalowicz, 273
/./'•'•//, 63 ; /.. i>nxilla, 56
bcdaria, 184/.
Liceaceae, 63
Hoffmann, 273
Labyrinthula, 39, 276,
Lieberkiihn, 84
Holmes, '206 n.
280 ; L. cienk«n:<l.-ii,
Life-history of Chlamy-
Holomastigoda, 164
280 ; L. macrocystis,
domyxa, 274 ; of Haemo-
holomastigote, 158
'-• 280, 282/. ; L. vilellina,
flagellates, 226 ; of Helio-
IliJn/i~tii;nm((, 286
129, 280, 282 /.
zoa, 15 ; of Lobosa, 75 ;
Homokaryota, 68
Labyrintlmleae, 39
of Mastigophora, 155,
Hoogenraad, 13
Lachnobohts, 64
162, 164, 172, 180, 189;
Hosts of Haemoflagellates,
Lamblia intestinodis, 170
of Mycetozoa, 40, 58,
list of, 262-268
I.iiiii/io.rniit!ui/iii ninrmy-
."'.i ; of Proteomyxa, 3 ;
Huxley, 151
anum, 144
of Radiolaria, 104, 111
Hycdobryon, 157, 158, 174
Lamproderma, 62
Lignii-res, 218 n., 219, 271
Hyalodiscns, 80
Lamprosporales, 63
lime-knots, 55
lhi<ti<,li<,fl]if. 34
Lang, A., 13
Liit/Hi/fii/i/i, 63
IIi/il,unn, 40
Lankester, on Chlamy-
Lingard, 271
lliiilriii-l'ni'rn* capybara,
domyxa, 274, 277, 280 ;
Linf/lij/a, 2, 8
252
onHaemoflagellates, 195,
liniii, 18
Hydrodictyon, 179
270 ; on Heliozoa. 17,
Lister, A., 61, 67
Hydrnrna, 176
36; on Ijiliirintlmla.,
Literature, of Chlamydo-
'inonas, 161, 176
283 ; on Lobosa, 80 ;
'inii-i'ii, 279 ; of Hsemofla-
hypnocysts, 4
on Mastigophora, 158 ».,'
gellates, 268 ; of Heliozoa,
liypothallus, 54
162, 168 H. : on .Myce-
35 ; of La bi/riji tl nln.
tozoa, 67 ; pu Radiolaria,
' 283 ; of Lobosa, 91 ; of
Ji/iiii-Ju-ii/in'tlt'c., 71
152
Mastigophora, 191 ; of
Ijima, 91
Larcoidea, 145
Mycetozoa, 66 ; of Pro-
Immermaun, 110, 153
Laveran, 196, 204, 206 7?.,
teomyxa, 13 ; of Radio-
Ineffigiata, 179
207, 218 n., 245. 252,
laria, 151 ; ofXenophyo-
isomastigote, 158
268, 270, 272, 273
jilioridae, 286
292
INDEX
Lithamoeba, 80 ; L. discus,
Mikroyromia, 39, 281
18 ; iu Actinosphaerium,
80 /.
Miuchin, 159 n., 192, 196,
25,32; in Labyrin tlmln,
Lithelius arborescens, 145 ;
199, 200, 201, 203 n.,
280 ; in Lobosa, 70, 86 ;
L. minor, 145
230, 231, 233, 246, 271
in Mastigophora, 161 ; in
Lithocircus annular is, 105
Mitrophauow, 195, 271
Mycetozoa, 48, 59 ; in
/., 146
Monadiua, 38, 248
Proteomyxa, 2 ; in Radio-
Lithocolla, 34
Monadineae, 5, 6 n.
laria, 94, 107, 110, 120
Lithogromia silicea, 148
Monadopsis, 8
Litholophus, 111
Monas, 166, 167
Oat-shaped corpuscles, 39,
Lithomelissa setosa, 147 ;
Monera, 1
274
L. thoracites, 147
Monobia, 3, 5/., 6, 15
Ochromonas, 157, 174
Litlwspluierella, 34
Monocercomonas, 169
Oedogonium, 8
Lobosa, 68 ; ehromidia, 71 ;
Monolabis, 22
Oicomonas, 157, 165 ; 0.
classification, 77 ; litera-
Monomastigoda, 165
mutabilis, 166 /. ; 0.
ture, 91 ; nucleus, 70 ;
Monomastigote, 158
termo, 166/.
reproduction, 72
Monomastix, 159, 170
Oligonema, 64
Lohmami, 174, 192
Monophyes gracilis, 249
Olive, 60, 66, 67
Lophomonadina, 170
Monopodittm, 8
Oread el la, 63
Lophomonas blattarum,
Monopylaria, 103, 107
Ornithocercus, 186, 187 ;
178 /.
Monostomatina, 169
0. magnificus, 184 f.
Lotsy, 192
Monticelli, 13
Orosphaera, 122, 144
Liihe, 245, 247, 268
Moore, 159 n., 192, 206 n.
Orosphaeridae, 144
Lycogala, 56, 64
Mucorinae, 40
Ostenfeld, 36
Lycogalaceae, 64
Mugliston, T. C., 93
Ouramoeba, 78/., 79
Miiller, Johannes, 131, 151
Oxyrrhis, 163 n., 168,
Mallomonas, 161, 176
Multicilia, 160, 163, 164;
184/.
Margarita, 64
M. lacustris, 164
Oxytoxum, 187
Margaritaceae, 64
Murray, J., 13, 113, 192
Martini, 91
Murrayella, 187
Palmella, 180
Mastigamoeba, 160, 164;
Musgrave, W. E., 93
Palmella stage in Zoo-
M. schulzei, 164
Mycetozoa, 37 ; classifica-
xanthellae, 98 ; in Flagel-
Mastigella, 156, 163, 164,
tion, 61 ; life-cycle, 42 ;
lates, 156
177 ; M. i-itraea,159f.,
literature, 66
Palmodactylon, 180
164 /. ; M. vitrina, 164
Myxastrum, 3, 5, 8
Palmodictyon , 180
Mastigina, 160, 164 ; M.
Myxodictyum, 11
Pandorina, 182
setosa, 164
Myxodiscus crystalligerus,
Pantostomatiua, 164
Mastigophora, 11, 155 ;
33
Paramastigoda, 167
classification, 163 ; habit,
Myxosphaera coerulea, 140
paraniastigote, 158
157 ; literature, 191 ;
Pi'.miiieciiiiit, 20 ; P. cos-
nucleus, 161 ; nutrition,
Nabarro, 199, 252
tatum, 195 ; P. lorica-
157 ; structure, 158
Nadinella, 90
tum, 195
Maupas, 20
Nagana, 195, 197, 198
Paramoeba, 79; P. eUhardi,
Maupasia, 159, 170
Nassellaria, 107, 113, 114
70 /., 73, 75, 79, 83;
Mayer, 195
Nationaletta, 149
P. hominis, 79, 83
M'Neal, 217, 218 n., 223,
Nawaschiu, 11, 13
Paramoecoides, 250
227, 240, 242, 244, 245,
Nebela, 85, 87, 90
Paranema, 171 ; /'. trlcho-
253, 271
nebenkorper, 70
phorum, 166/.
Medusetta tiara, 148
Nepveu, 196
Paranemina, 171
Medusettidae, 148
Neresheimer, 71, 91
Parmulina, 89
Megastoma, 157, 169; M.
Neusina agassizii, 284
Patton, 242, 259, 271, 273
entericum, 169
Noctiluca, 162, 188, 190 ;
Pediastrum, 179
Menoidium, 171
N, miliaris, 161 /., 189
Pelomyxa, 2, 68, 70/., 71,
Mereschkowsky, 13
/., 190 /., 191 /.
73, 75, 76 /., si ; P.
Mesenteries, 44
Novy, 200 n., 217, 218 n.,
palustris, 72 /., 76 ./'.,
Mesnil, 91, 196, 204, 206,
227, 239, 240, 242, 244,
81 /. ; P. penanU. 81 ;
207, 218 n., 245, 252,
245, 253, 271
P.villosa,Bl; I', viridis.
272, 273
Nudearia, 8, 9, 14, 15, 23,
81
Mesoscena, 114
33 ; N. ddicntula, 10/.
Penard, E., 13, 22, 23, 33,
Metschnikoff, 50, 67
Nuclei in Chlanu/domyxn,
36, 39, 67, 91, 274, 277,
microcysts, 42
274 ; in Haemotta^ellates,
278, 280
Microglena, 161, 176
194, 212 ; in Heliozoa,
Penardia, 3, 9
INDEX
293
Perichaena, 64
Plate, 190
Protogenes, 5, 9 ; P. jtriin-
Peridiniaceae, 185
Platnaspis, 146
ordialis, 9/.
Prridinium, 186 187 ; P.
Platoion, 90
Protomastigiua, 165
dicergens, 186 /.
Platydorina, 158, 182 ; P.
Protomonas, 11, 60 ; P.
Peripylaria, 102
caudata, 182/.
amyli, 38 ; P.paroaitii-n,
Perrin, 273
Platytheca, 167
38
Petalomonas, 171
Plectellaria, 147
Protomyza, 3, 4, 7/1, 11 ;
Pliaeoconchia, 150
Plectoidea, 147
P. parasitica, 10 /.
Phaeocy.stina, 147
Plectophora arachnoides,
Prototrichia, 64
Phaeodaria, 108, 113
147 ; P. novena, 147
von Prowazek, on Haemo-
Phaeogromia, 148
Plehn, 271
flagellates, 198, 205,212,
Phaeosphaera, 176
Plenge, 42, 67
223, 229, 231 M., 232,
Pliaeosphaeria, 148
Pleodorina, 181, 182 ; P.
257 71., 271 ; on Helio-
Phalaeroma, 188
illinoisensis, 183 f.
zoa, 35 ; on Mastigo-
Phalansteriina, 177
Pleurococcus, 179
phora, 159 H., 163, 192 ;
Barium, 158, 163«..
Pleuromonas, 167
on Proteomyxa, 4 w.
177 ; P. consociatum, 166
Plimmer, 206 ?i., 269
Prunocai-pi's d'.<tn,-a, 145
/. ; P. volvocis, 168
Podolampas, 187
Pmnoidea, 145
Pkarynyella gastrula, 148
Polykrikos, 185
Prunophracta, 146
Plwrmobotrys hexathalom iu,
Polymastigiiia, 169
Psammeftn, 286
147
polymastigote, 158
/'^rt?;! »; //ia gldbigerina,
Phorl iciu m pylon in m, 145
Polyoeca, 177
285/.
Phractopeltidae, 146
Polyplagia novenuria, 147
Psammini<Ii/c, 286
Phryganella, 90
Polyporus, 40
Psamr/uijie/nmii, 286
Phyllomitus, 167
Polysphondylium, 60, 65 ;
Pseudamphimonas, 11, 12
Phyllomonas, 167
A violaceum, 60/.
Pseudochlamys, 89
Phyllostaurus, 146 ; P.
Polytoma, 177 ; P. nvella,
Pseudodijfluyia, 90
<[U<n! rifolius, 146
178/.
Pseudopodia, of Heliozoa,
Physaraceae, 56, 62
Pompholyxophrys, 22, 24,
23 ; of Lobosa, 85 ; of
Physarella, 62
34
Mastigophora, 160 ; of
Physarum, 52 ?;., 55, 62 ;
Pontigutasia,89 ; P. incisa,
Proteomyxa, 3; of Radio-
P. mutans, 54 f.
89/.
laria, 96, 106
Physematiidae, 104, 144
Pontobdella, 204, 224,
Pseudospora, 3, 5, 8, 163
Physematium, 121 ; P.
228
Pseudosi><>ri<?him, 10, 12
niiiUcri, 144
Pontomyxa, 9 ; P. Jtaca,
Ptychodisfidao, 187
J'hysomonas, 167
9 ; P. pcdlida, 9
PtycKo&iscus nocticula, 187
Phytheliii-ft, 33
Pontosphaera, 176 ; /'.
pulsellum, 158 H.
PhytoHagellata, 177
haeckelii, 175/.
Putter, 98, 153
P inaciophora, 24, 34
Popowsky, 136, 153
'•'•H/H'iias (=J'yra-
Pinacocystis, 21, 24, 34
Porocapsa, 146 ; P. wittr-
mimonas), 179, 180
Piroplasma, 256 ; P. <2ouo-
rayana, 146
Pi/riil>}ui,-nxl 187
Ewnt, 243, 257 /., 259
Poroapathidae, 148
/'// > iilicuia, 91
Playiacantka arachnoides,
Poteat, \V., 91
147
Poteriodendron, 158, 161,
Quadrula, 84, 85, 89 ; <,>.
Plagiocarpa procyrtella,
168
'/ulin'is, 84
147
Pouchetia. 185
Quatrefages, 189
Plagoniscus tripodiscus,
I'm, if I, 192
107/.
Pricolo, 171
Rabinowitscli, 198, 272
Planktonetta attantica,
Proales, 23
Radiolaria, 94 ; bionomics,
120/., 149 /.
Prorocentraceae, 185
96 ; central capsule, 114 ;
Plasmodiocarps, 56
Protamoeba, 2, 5, 6
classification, 144 ; cyto-
Plasmodiopfwra, 2, 3, 4 «.,
Proteomyxa, 1
plasm, 116 ; distribution,
5, 11
I'roterosponyia, 158, 177 ;
112; food, 97; literatim-,
Plasmodium, in Labyrin-
P. haeckelii, 178 f.
151 ; nucleus, 120 ; repro-
fh/'/fi, 282 ; in Lobosa,
I*r/>tn!Kithybiiis, 12
duction, 136 ; skeleton,
72 ; in Mycetozoa, 43,
Protocerativ.m, 187
130 ; variation in, 110 ;
57 ; in Proteomyxa,3
Protococctis, 180
yellow cells, 126
plasson, 2
Protocystis harstoni, 148 ;
Raphi'l.iiiiK'iitix, 174
plastogamic fusion, in
P. tridens, 148 ; P. <ri-
Reinak, 195
Heliozoa, 19; in Lobosa,
/o/(/x. 148 ; P.xiphmhn,
Reproduction, in Chlamy-
88
148
domyxa, 275 ; in Hae-
294
INDEX
moflagellates, 222 ; in
Schneider, 5/., 13, 31, 32,
Stannoma, 284, 286
Heliozoa, 19, 28 ; in
205, 269
Stanuoniitla, 286
Lobosa, 72 ; in Masti-
Schroder, 122, 153
StannophyUum, 284, 286 ;
gophora, 156 ; in My-
Sclmberg, A., 92
S. zonarium, 284 f.
cetozoa, 41 ; in Proteo-
Schubotz, 92
Statham, 257, 272
myxa, 4 ; in Racliolaria,
Schultze, 285, 286
Steel, 195
99, 136
Schiitt, 187, 192
Stegomyia, 240
Reticularia, 52 n., 56, 64 ;
Sclerotiuin, 44, 50
Steiniella, 187
R. lycoperdon, 42/.
Scyphosphaem, 176 ; S.
Stemonitaceae, 53, 62
Reticulariaceae, 63
apsteini, 175./'.
Stemonitis, 62 ; S. ferrii'
rhabdoliths, 174
Scytomonas, 171
ginea, 55 /. ; S. fusca,
Rhabdomonas, 171
Selenastrnm, 179
41 /., 57 ; S. splendens.
Rkabdosphaera, 176
Seim, 192, 212, 272
55 f.
Rlwphidiophrys, 22, 24,
Sergcnt, 196, 226, 272
Stephanosphaera, 158, 182
28, 34 ; R. elegans, 35 /. ;
Siedlecki, 273
Stephoidea, 147
R. pallida, 16 /. ; R.
Siphonosphaera, 121, 123
Stereum, 49
viridis, 22, 23
Siphoptychium, 63
Sterromonas, 167
Rlutpkidocystis, 24, 34
Smith, 31, 36
Stichogloea, 176
Rhipidodeiidron, 158, 168
Sorokin, 13
Stole, A., 92
Rhizomastigoda, 164
Sorophora, 39, 59, 65
Stomoxys calcitrans, 199 /.
Rhizoplasma, 9
Sphaerastmm, 28, 34
Strasbnrger, 52 n., 67
Rhizoplegma boreale, 145
Sphaerella, 179, 180 ; S.
Streptomonat, 168
Rhunibler, 5, 6 n., 13, 70,
jacdustris, 166/.
Stuhlmann, 200, 203, 216,
85, 91
Sphaerellaria, 106, 113,
230, 231, 272
Rhynchomonas, 168
114
Stylamoeba, 80
Robertson, 163, 169, 192,
Kphaerocapsa, 146 ; <S.
Stylochrysalis, 157, 163 n.,
204, 214 n., 216 n., 224,
c-niciata, 146
174
228, 229, 272
Sphaerocapsidae, 146
Swingle, 225 n. , 272
Rogers, 226, 257, 272, 273
Sphaerocystis, 180 ; S.
Symbiotic Algae (Peridin-
Romanowsky, 196
Schroteri, 22
' ians), 94
Roubaud, 203 n., 231 n.
SpJiaeroeca, 158, 177
Syncrypta, 173, 176 ; S,
Ross, 240, 242, 272
Sphaeroidea, 145
voh-ox, 166/.
Jiitppia, 3
Sphaerophracta, 146
Synura, 157/161, 176
Sphaeropylidea, 145
Syracoaphaera, 176
Sphaerozoa, 102, 104, 145
Syracosphaerinae, 176
Sagena ternaria, 148
Sphaerozoidac, 104, 145
Migenoarium, 148
Sphaerozoum neapolitanum,
Sagospkaera trigonilla, 148
138, 141/. ; S. ovodimare,
Tabanus, 242 ; T. lineola,
Sagosphaeridae, 148
145
199 /.
Salpingoecct, 161, 177; S.
Spkenomonas, 171
Tansley, 180, 192
fusiformis, 178 /.; S.
Spirilla, 195
Tanypu-s, 245
urceolata, 178/.
Spirochaeta evansi, 195
Tetramitus, 157, 169 ; T.
Saltonella, 80
Spirodinium, 183, 185
rostratus, 178 f. ; T. sul*
Saunders, 49
Spirogyra, 7, 8, 32
catus, 178 f.
Schaudinn, on Haemofla-
Spiroidea, 147
Tetramyxa, 2, 3, 11
gellates, 196, 198, 202,
Spironema, 170
Tetraspora, 180
205, 212, 217, 226, 235,
Spirula, 11
Thalassicolla, 94, 113, 114,
241 n. , 248 n., 258, 272,
Spongodisms favus, 145
123 ; T.pelagica, 95 /. j
273 ; on Heliozoa, 27,
Spongomonas, 168
T. pellucida, 144; T.
29, 32, 34, 36 ; on
Spongosphaera streptacan-
nitcleata, 98, 99, 101/.,
Lobosa, 70, 75, 87, 88,
tha, 105/.
103/., 144; T.spumida,
92 ; on Mastigophora,
Sporangia, 50
144
163, 192; on Proteo-
Spores in Mycetozoa, 53 ;
Thalassicollidae, 104, 144
myxa, 6 n. ; on Radio-
in Proteomyxa, 4
Th alassiosolen atlant icns,
laria, 153
Sporophore, 58
144
Scheel, 74, 92
Spumaria, 56, 57, 62 ; S.
Thalassolampe, 121 ; T.
Schewiakoff, 118, 131, 153
alba, 54/.
margarodes, 144
Schizochlamys, 180
Spumellaria, 113
Thalassophysa, 120 ; T,
Schizogenes, 12
Staborgan, 188
papillosa, 144 ; T. pel a*
Schleiincysten, 232
Stahl, 61, 67
gica, 138 /., 144 ; T.
Schleppgeissel, 194, 218
Stannariiim, 286
sanguinolenta, 128 f. ,
INDEX
295
138 /., 144 ; T. ,^/<v-
247, 249 ; 71. iwrttaa,
ii.rimn, 195 /., 254 ; T.
losa, 138/.
249
scyllii, 204, 255 /. ; T.
Thalassophysidae, 104, 144
Tn/j>anoscmia, 157, 163,
soleae, 210 /., 217 ; T.
Thalassothamnidae, 144
168, 177, 248, 250 ; T.
theileri, 199 /., 209,
Thalassothamnus, 122 f. ;
ai'iKM, 208/., 217, 253 ;
251 n., 253 ; T. tmns-
T. ramosus, 144
T. ba-rbdtulae, 215, 227,
vaaliense, 216, 253 ; T.
Thecamoebida, 68, 84
228, 230 ; T. boneti, 254 ;
ugandense, 252 ; T. tai-
Theoconus ariadnes, 147
T. brucii, 195, 199 /.,
dulans, 255 ; T. mriuiii,
Thiroux, 218 «., 239, 272
200, 201, 203, 208 /.,
227 ; T. ziemanni, 205,
Thread -plasmodium, 39,
209, 214, 215, 216, 217,
208 /., 233, 237 /., 238,
281
220 /., 221 /., 223 /.,
253
Todd, 255
231, 233 ; T. carassii,
Trypaiiosomatidae, 248
Topfer, 237 u.
255 ; T. cobitis, 255 ;
Trypanosomes, 193, 213 f.
Topsent, 13
T. costatum, 254 ; T.
Trypanozoon, 248
Torrey, 237 n.
damoniae, 208 /., 254 ;
Tsetse-fly, 196, 201 n.
Ti-achelomonas, 161, 171
T. danilewskyi, 204 ; T.
Tubulina, 63 ; T. stipitata.
tractellum, 158 n.
dimorphon, 253 ; T.
56
Trepomonas, 169
duttoni, 205 ; T. elegans,
Tubulinaceae, 63
Trepospyris corliniscus,
255 ; T. elmassiani, 253 ;
Tulloch, 199, 200, 203,
107 /.
T. equinum, 197, 199/.,
230
Trichamphorn, 62
205, 208 /., 217, 220 /.,
Tuscarora national is, 122
Trichia, 52 n., 64 ; T.
221 /., 224 /., 251 /.,
/., 150 /.
fallax, 52 n., 53 ; T.
253 ; T. equiperdum,
Tuscaroridae, 150
varia, 53/., 56 /
197 n., 205 /., 209,
Tiiscarvsa globosa, 150/.
Trichiaceae, 44, 55, 64
224 /., 251 /., 253; T.
Trichoinastix, 157, 169
evansi, 199 /., 253 ; T.
Trichomonas, 157, 160,
flesi, 255 ; T. gambiense,
Ulothri.c, 156
162,169 ; T. intestutoltg.
196, 197 n., 199, 200,
Ulotrichaceae, 156
169
203, 208 /., 220 /., 221
Umbilicosphaera, 176
Trichosphaerium, 22, 68,
/., 230, 251 /., 252; T.
Undwliiia, 250
72, 73, 75, 80, 102, 127
granulosum, 204, 209,
Urceolus, 171
Ti-i'J/'i.-tyopus, 115 ; T. efe-
210 /., 228, 255; T.
Uroglena, 158, 173, 176 ;
<?«««, 147
grayi, 200 n., 201, 215,
U. ranarum, 106 /., 194
Trigonomonas, 169
216/..224/., 231, 232/.,
/., 195, 254 ; U. wlvox,
Trimastigina, 169
233, 245, 246, 251 ; T.
166/.
Trimastix, 169
liannae, 208/., 209, 216,
Urophagii-s, 169
Triposolema, 188
253, 254 ; T. inopina-
Tripylaria, 102, 108. 147
fi'ni, 210 /., 216, 255 ;
Trochiscia, 179
T. johnstoni, 214 «.,
Vacuolaria, 174
Trochodiscus ech in /*••//..,•,
253 /., 254 ; T. karyo-
Vahlkampf, 70, 92
145 ; T7. heliodes, 145
zeukton, 210 /., 212,
Valentin, 194
Trophochromidia, 71
255 ; T. lewisi, 197, 198,
Vampyrdla, 2, 3, 4/., 5,
Trophonucleus, 214
203, 204, 205, 207 /.,
7/., 15, 33
Tropidoscyphus, 171
208 /., 210, 211 f., 214,
Vampyrellidium, 2, 3, 8
TruncatidincT, 112
216, 217, 219 /., 222,
Veley, 71, 81, 92
Trypanomonas, 250
225 /., 226 /., 229,
Vernon, 98, 152
•"Hiorpfia, 167, 198,
251 n., 252 ; T. mega,
Verworn, 13, 95, 152
238, 248
212, 255; T. nanum,
Voges, 272
Trypanomorphidae, 167,
209 ; T. ndspruitense,
Volvociua, 181
248
210 /., 255 ; T. noctuae,
Volvox, 158, 181 ; V.
Trypanqphis, 168, 209,
198, 202, 205, 208 /.,
aureus, 182 ; V. globator,
211, 213, 216, 249; 71.
213, 218, 219 /., 223,
166 /., 181 ; V. minor,
grobbeni, 211, 249 /.,
233, 242, 243, 247, 248 ;
166/. ; V. tertius, 182
250
T. paddae, 253 ; T.
Trypanoplasma, 168, 209,
polyflectri, 209 ; T. raiae,
211, 217,249; T.borreli,
204, 209, 216, 224, 228,
Wagnerdla, 34
210 /., 211, 215 /., 216,
231, 255 /. ; T. remaki,
Wasielewsky, 212. 272
217, 249; T. cjjprini,
204, 209, 210 /., 216 ;
Watase, 189
210 /., 211, 249 ; T7.
T. rotatorium, 208, 209,
Weuyon, 192
intestincdis, 247, 249,
210 /., 216, 248 «.,
West, G. S., 13, 36,
250 /. ; T. rentriculi,
250 n., 254 ; T. sangulnis
192
296
Wolfenden, 113, 152
Woodcock, 193 n., 268
Woronin, 3, 13, 58, 66,
173, 192
Wright, S., 13, 256, 273
Xanthellae, 22
Xenophyophoridae,
286
284,
Xiphicantha (date, 128,
142 /., 143
Zederbauer, 192
Zoochlorella act in osph aerii,
22
Zoospores, in Mycetozoa,
40 ; in Proteomyxa, 4
Zooteirea, 33
zooxanthellae, in Radio-
laria, 97
Zopf, 2, 5, 6 n., 13, 39,
60, 61, 67, 280, 281,
283
Zuelzer, 71, 86, 87, 92
Zygacantha, 146 ; Z. sep-
tentrionalis, 146
Zygoselmis, 171
Printed by R. & R. CI.ARK, LIMITED, Edinburgh.