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A TEEATISE ON ZOOLOGY

A TREATISE ON ZOOLOGY

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Part II. THE PORIFERA & COELENTERA

By E. A. MINCHIN, M.A., Professor of Zoology at University
College, London; G. HERBERT FOWLER, B.A., Ph.D., late
Assistant Professor of Zoology at University College, London ;
and GILBERT C. BOURNE, M.A., Fellow and Tutor of New
College, Oxford.

Part III. THE ECHINODERMA

By F. A. BATHER, M.A., Assistant in the Geological Department
of the British Museum ; assisted by J. W. GREGORY, D.Sc.,
late Assistant in the Geological Department of the British
Museum, Professor of Geology in the University of Melbourne,
and E. S. GOODRICH, M.A., Aldrichian Demonstrator of
Anatomy in the University of Oxford.

Part IV. THE PLATYHELMIA, MESOZOA,
AND NEMERTINI

By W. BLAXLAND BENHAM, D.Sc. (Lond.), M.A. (Oxon.), Pro-
fessor of Biology in the University of Otago, New Zealand ;
formerly Aldrichian Demonstrator of Anatomy in the University
of Oxford.

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THE MACMILLAN COMPANY
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TREATISE ON ZOOLOGY

EDITED BY

E. RAY LANKESTER

M.A., LL.D., F.R.S.

HONORARY FELLOW OF EXETER COLLEGE, OXFORD J CORRESPONDENT OF THE INSTITUTE

OF FRANCE I DIRECTOR OF THE NATURAL HISTORY DEPARTMENTS

OF THE BRITISH MUSEUM

PART I

INTKODUCTION AND PEOTOZOA

SECOND FASCICLE

BY

J. B. FARMER, D.Sc., F.R.S.

PROFESSOR OF BOTANY, ROYAL COLLEGE OF SCIENCE, LONDON

J. J. LISTER, M.A., F.R.S.

FELLOW OF ST. JOHN'S COLLEGE, CAMBRIDGE

E. A. MINCHIN, M.A.

PROFESSOR OF ZOOLOGY, UNIVERSITY COLLEGE, LONDON
AND

S. J. HICKSON, F.R.S.

PROFESSOR OF ZOOLOGY, OWENS COLLEGE, MANCHESTER

LONDON

ADAM & CHAKLES BLACK
1903

r ,rs

PREFACE TO SECOND FASCICLE OF PART I.
INTRODUCTION AND PROTOZOA

THE irregular publication of the parts of the Treatise on Zoology
is the inevitable result of the fact that it is the work of a
number of authors.

I have determined not to allow Professor Minchin's most
timely and valuable treatise on the Sporozoa to lie by in the
printers' hands until the other sections of Part I. which
logically precede it are ready for the press ; and with this I have
been able to combine Dr. J. J. Lister's section on Foraminifera
(which contains much that is new and original), Professor
Hickson's section on Infusoria, and a section on the Structure
of Animal and Vegetable Cells, with especial reference to the
points which arise in the study of the Protozoa, by Professor
Farmer.

These four sections form the second fascicle of the First
Part of this treatise ; the first fascicle, which is in preparation,
will contain an Introduction and descriptions of the Proteo-
myxa, Mycetozoa, Lobosa, Heliozoa, Labyrinthulidea, Radio-
laria, and Flagellata, forming sections A to G of Chapter I. —
The Protozoa.

The division of the work into Chapters, of which the
second to the twenty -first are already published, has resulted
in a somewhat awkward restriction of the Protozoa to nominally

vi PREFACE

one chapter, the first. This unduly large chapter is broken
up into sections which serve instead of the usual division of
so large a number of pages into chapters. The parts of the
Treatise on Zoology dealing with the Mollusca, the Arthropoda,
and the Vertebrata are in active preparation.

E. EAY LANKESTEB.

May 15, 1903.

CONTENTS

CHAPTER I— PROTOZOA (continued}

PAGE

SECTION H. — THE STRUCTURE OF ANIMAL AND VEGETABLE

CELLS ..... 1

„ I. — THE FORAMINIFERA . . .47

„ K. — THE SPOROZOA . . . .150

„ L. — THE INFUSORIA . .361

INDEX 427

CHAPTER I.— PEOTOZOA (continued}

SECTION H. — THE STRUCTURE OF ANIMAL AND VEGETABLE
CELLS1

IN reviewing the course of development of our knowledge of
organic nature, there stands out one epoch-making discovery, that
of the chambered structure of plants, made by Hooke in 1665,
which was destined not only to profoundly modify the older con-
ceptions as to the intimate organisation of animals and plants, but
also to place in clear relief the fundamental unity which underlies

FIG. 1.
Facsimile of part of a figure by Hooke representing cells of vegetable tissues (cork).

the apparently endless variety of external form. But, as in the case
of most discoveries of wide-reaching import, the general recognition
of the true nature of the cell did not emerge at once in its modern
form, nor was it in reality the outcome of the work of any single
investigator. Indeed, nearly two hundred years elapsed before the
first enunciation of the doctrine of a cellular structure of plants

1 By J. B. Farmer, D.Sc., M.A., F.R.S. (1902).
I

THE STRUCTURE OF CELLS

by Hooke became translated into a form comparable to that in
which the phrase is now understood.

Nevertheless to Hooke belongs the credit of having not only
depicted the vesicular nature of cork and other plant-structures, but
also of having designated the cavities by the name of cells.

Malpighi and Grew in the succeeding century had fully recog-
, nised the cellular character of plants, and even attempted a crude
explanation of the origin of the cells themselves, likening them to
the vesicular foam of beer. But accurate as was their portrayal
of the mature structure, they nevertheless possessed no real concep-
tion of the true meaning of the cell as the unit of organic life.
The cells were regarded as the cavities in the matrix, not as the
units which together constitute the organism, and it was to the wall
that all their observations were directed. Little or no attention
was seriously paid to the cell-contents. Thus, although Corti in 1772
had noticed the rotation of the viscous matter in the cells of Chara,
his discovery remained without influence, and was made again, and
independently, by Treviranus some forty years later. Even the
discovery1 of the nucleus by R Brown in 1831-33 failed at once to
excite the interest of the majority of his contemporaries, nor indeed
does it appear that Brown himself at all fully grasped the signifi-
cance of his discovery. Whilst in the plant-body it was the cellular
structure, in the sense of Hooke, Malpighi, and Grew, which most
forcibly appealed to the observer, the softer tissues composing an
animal body were not so easily referable to a similar plan, although
a consideration of the blood corpuscles, and of cartilage, helped to
pave the way for the later generalisation. But, on the other hand,
the animal body was more suited to turn the attention of the
investigator upon the living substance, and the fundamental
importance of the latter seems to have been first clearly appre-
hended by Dujardin, who (in 1835), gave the name of Sarcode to
the contractile, gelatinous, diaphanous mass constituting the bodies
of the Infusoria which he was examining. He even succeeded in
distinguishing some structural details, but with the lens at his
command it may perhaps be doubted whether this really repre-
sented more than the arrangement of granular and other inclusions
in the living substance.

It was, however, chiefly due to the researches of Schleiden, and
especially of Schwann, which were published in 1837-38, that
general interest became steadily focussed upon the cell-contents,
including the nucleus which formed a cardinal point in their famous
cell-theory. And it is largely to the great influence exerted by
their work that the rapid advances witnessed during the next
succeeding decades are legitimately to be traced. It is, of course,

1 Others, including Leewenhoeck, had already seen nudei in isolated cases, but
their observations were quite without influence on the development of thought.

THE STRUCTURE OF CELLS

true that the greater part of their conclusions, especially such as are
related to the genesis and growth of cells, have since turned out to
have been erroneous. This is largely due, perhaps, to the weight
of mistaken preconceptions on their part ; but the history of advance
in any line of thought or science is full of similar examples. It is
sufficient that they realised to the full the immense importance of
the inquir}', and at any rate they succeeded in correlating and in
co-ordinating a large mass of observations, and so became the means
of immediately attracting numerous other workers into the same
field.

To Schwann may be conceded the merit of having first con-
sciously attempted to demonstrate, in the most effective manner,
the essentially similar character of the cells in plants and animals.
This he did by endeavouring to follow out the origin and develop-
ment of new cells in each of the two great divisions of living
organisms, though how wide he was of the practical truth may be
seen from the account which he gives of the process. The
primordial substance out of which cells are formed consists,
according to him, of a gelatinous or slimy mother-liquor, the
cytoblastema. In this, by a process of condensation, a nucleolus is
first formed. This then grows by intussusception, and gives rise
to a nucleus, in which once more a nucleolus is differentiated —
itself the origin of another nucleus. Meantime, from the cyto-
blastema fresh matter is deposited in the surface of the nucleus, and
thus a consolidated membrane originates. This membrane, by
intercalation of constantly increasing material within it, continues
to grow, and ultimately it forms the wall of the new cell, the
contents of which are provided for in the way just described.
Thus, in the formation of cells, according to Schwann, the following
stages, starting from the raw material — cytoblastema — may be
distinguished. First, the condensation giving rise to the nucleolus,
this in turn, by growth, produces the nucleus, and the peripheral
(nuclear) Avail eventually forms the wall of the new cell. At first
sight it is difficult to realise how these ideas obtained the wide
currency which they enjoyed, but the reason is to be sought in the
fact that Schwann, like Schleiden and Nageli after him, was not
fortunate in the material he selected for investigation. Cartilage,
blood-corpuscles, and pollen grains were repeatedly studied, and it
is perhaps not surprising that with such objects before them an
incorrect conclusion was arrived at.

Von Mohl, who had been engaged in studying the structure and
mode of division of vegetable cells since 1835, at one time gave a
true explanation of the process, but afterwards he sounded a less
certain note, adhering to the view that the new cells were formed
in toto within the mother cells, even in the case of algal filaments —
an error which was definitely opposed by linger. Von Mohl

THE STRUCTURE OF CELLS

clearly recognised the importance of the formative substance of
the cell, to which in 1846 he gave the name it now bears, viz.
Protoplasm, the same word that had already been employed six years
earlier by Purkinje to designate the formative substance met with
in the animal embryo.

Speculation was already aroused as to the possibility of
instituting a comparison between vegetable protoplasm and animal
sarcode, and Dutrochet had, as early as 1824, and still more
definitely in 1837, indicated the general similarity which underlies
the structure of animals and plants. But it was reserved for Cohn
to clearly formulate in 1853 the real features of identity between
them, and to express the definitely reasoned view that they were,
in all essentials, composed of the same kind of substance. Cohn
was well fitted for the task, by his acquaintance with the lower
organisms of both animal and vegetable kingdoms. Max Schultze
in 1861 further elaborated this resemblance, and his convincing
demonstration at once gained the assent of all who were competent to
form an opinion on the question. Moreover, Schultze clearly saw
that it is the protoplasm (in the widest sense of the term) which
essentially constitutes a cell, and he, like Leydig, defined it as a
mass of protoplasm containing a nucleus. About the same time
also Virchow, in his celebrated aphorism, " Omnis cellula e cellula,"
crystallised the correct view as to the general mode of origin of new
cells.

But although the essential facts of cell-structure and development
thus gradually emerged from the earlier and cruder notions, the
finer details, and especially the relations of the nucleus, long
remained obscure. The origin of this body, and its connec-
tion with the rest of the cell-contents, was not understood, and
a very general view was held that it disappeared (as indeed is in a
certain sense correct) at each cell-division, to be formed afresh in
the new daughter cells. It is true that so long ago as 1841 Kemak
had put forward the statement that the nucleolus and nucleus gave
rise by direct fission to the corresponding structures in the
daughter cells, arid indeed that the whole process of cell -division
was thus inaugurated ; but his views (which for a few cases
are really well founded) appeared to be not generally applicable, and
thus it transpired that even in the middle of the century the
nucleus came to be commonly regarded as an organ of but secondary
importance, and this even by so eminent an investigator as
Briicke. It was not until the publication of Strasburger's mag-
nificent work on the cell- and nuclear-division in 1875 that the
nucleus received its proper share of attention. Strasburger, some
four years later, like Virchow, in another connection, before him,
defined the modern position in the phrase "Omnis nucleus e nucleo."
The researches of the brothers Hertwig, Van Beneden, Flemming,

THE STRUCTURE OF CELLS 5

and others have abundantly emphasised and justified these far-
reaching generalisations.

But with the improvements which have been effected in
technique during the last quarter of a century, new facts have
come to light which have somewhat modified the conception of the
cell as held by the earlier writers. It has been already seen how
the centre of gravity gradually shifted from the cell-wall to the
cell-contents, and that, as Max Schultze declared, the essential
constituents of the cell were represented by the protoplasm and the
nucleus, the wall being of altogether subordinate importance. The
discovery that masses of protoplasm might contain not one but
many nuclei, and that such a condition is not uncommon both
amongst various groups and tissues in plants and animals, appeared
to some writers to present a difficulty in accepting the cell theory
as treated above, and various explanations have been offered in
order to bring these cases into line with the theory as more
generally understood and defined. Such organisms or tissues
have been termed non- cellular — a negative and unsatisfactory
expression which has been replaced by the more appropriate word
syncytium or coenocyte. These words emphasise the view that, mor-
phologically, the individual units, which collectively make up the
syncytial tissue, are not isolated from each other by definite
barriers. Sachs proposed the term energid to express the cell in
Max Schultze's sense, meaning thereby the nucleus, together with
the portion of protoplasm dominated by it. Essentially this is
a physiological definition as contrasted with the morphological idea
embodied in the word syncytium. And it is, on the whole, a legiti-
mate expression, since it really does correspond to a fact. Moreover,
it has the merit of being equally applicable to the cases of isolated
cells as well as of those in which such limits are not structurally
traceable. The objection raised to the conception underlying it, on
the ground that the nucleus of a syncytium does not always dominate
the same protoplasm, is not a valid one, inasmuch as it is quite
possible — perhaps even probable — that an essentially similar state
of things also obtains even in those tissues in which the constituent
cells are apparently isolated. For it has gradually been proved for
a very large number of cases that the protoplasm of adjacent cells is
in actual physical continuity through the fine pores present in the
delimiting cell-walls. It is tolerably easy to observe this continuity
in the epithelial cells of some amphibian tissues, and there is a con-
siderable weight of evidence to show that it is far more general than
was generally supposed to be the case. In plant-tissues also it has
been repeatedly demonstrated since its first discovery by Tangl (in
1879)in the endosperm of certain seeds. Gardiner and Russow almost
simultaneously demonstrated its existence in the tissues of several
adult plants in 1883, and since that time it has been clearly proved to

THE STRUCTURE OF CELLS

occur throughout the tissues of the organism in those examples which
have been specially investigated for the purpose. Thus it is evident
that, so far from the syncytial condition presenting an exceptional
case, it is in reality an extremely common one, the cell-walls merely
forming a perforated skeletal framework which supports the softer
parts. It is useless to argue (as has recently been done) that the
pores are so fine as to be practically useless for the transference of
material substances through them, since, as Horace Brown has shown,
their very narrowness, taken together with the thinness of the portion
of membrane on which they occur, is an important condition for
the performance of such a function without unduly weakening the
framework itself. Moreover, the existence of the continuity of the
protoplasm from cavity to cavity at once renders intelligible the

FIG. 2.

Continuity of protoplasm through vege-
table cell-walls. A, cells of the pulvinus
of Robinia. B, cells of the endosperm of
lleterospathe.. (After Gardiner.)

possibility of a transmission of stimuli from one part of the body to
another, although it would perhaps be going too far to assume this
as a necessary condition of transmission. Examples are known in
which the stimuli appear to be less directly conveyed, as, for
instance, in the case of nerve ganglia, according to Ramon y Cajal
(although his results have not been upheld by some other investi-
gators) ; and further, in some plant tissues, water squeezed out
into the intercellular spaces has been regarded (on rather slender
grounds) as being the means of exciting consecutive cells of a tissue.
On the other hand, Nemec has recently shown reason for admitting,
in the irritable parts of plants, the existence of specialised tracts of
protoplasm which are continuous from cell to cell, and by the agency
of which the stimulant impulse is conveyed to the motor executive
region. Whilst the general and mutual relations of the constituent
parts of the cells were being gradually elucidated, it became recog-
nised that the cell-substances themselves were not composed of

THE STRUCTURE OF CELLS

mere structureless jelly, but possessed an organisation of their own.
At first the recognition of this fact only appears in tentative sug-
gestions, and hardly any serious progress was made beyond the
obvious distinction of the nucleus from the protoplasm. Briicke
seems to have been the first to point out the philosophical necessity
of assuming an organisation in the protoplasm, but the visual per-
ception of the counterpart of such a constitution hardly advanced
beyond the recognition of a relatively solid mass bathed in a more
fluid substance. The former was distinguished as spongioplasm,
and the latter as hyaloplasm. It is significant of the difficulty
experienced in arriving at a definite decision on the then available
evidence that each of the two constituents has been claimed In-
different writers as the living substance.

The views which have been put forward as to the relationships
of the various substances which co-exist in the protoplasm to each
other have developed in two principal directions. The earlier, his-
torically speaking, was advocated by Frommann in a series of papers
dating from 1864. He was led, by a study of nerves, to distinguish
a reticulum, which partly corresponds with Leydig's spongioplasm.
This reticulum was imbedded in a more homogeneous ground sub-
stance, which, however, includes much more than spongioplasm.
He extended this conception of protoplasmic structure to plant cells,
and it was utilised, and in some respects modified, by Heitzmann in
1873. The views of the latter author were not so convincing as
those of Frommann, for it is quite possible to identify the structures
described by the latter writer in living cells, although the appear-
ances are susceptible of a different interpretation from that given
by him. Heitzmann's descriptions, on the other hand, are very
schematic, and it is difficult to avoid the conviction that they are
highly coloured by theoretical preconceptions. The phenomena of
contraction and extension were brought by him in relation to the
structures as described, but his views have never met with very
general acceptance. A closely related hypothesis was that suggested
by Flemming, who, while denying the existence of a reticulum,
insisted on the presence of a fibrillar structure, the fibrils being
represented as threads of irregular length (the filar elements) which
were imbedded in a more fluid interfilar mass.

Gradually another view of the structure of protoplasm was
evolved, and which, in a measure, took account of reticular structure,
but explained it differently. Strasburger in 1876 first seems to
have spoken of closed protoplasmic chambers, which were filled with
more fluid albumen, but he soon abandoned the idea in favour of
the reticular hypothesis. But the alveolar theory thus indicated
was developed and extended by Biitsclili, who had, as long ago
as 1873, figured in Pilidium a structure susceptible of such an
explanation, though this was not given at that time. The alveolar

8

THE STRUCTURE OF CELLS

theory has exerted considerable influence upon contemporary thought,
and may be given in brief outline. The whole protoplasm, including
the nucleus, is conceived of as in a physical condition resembling
an emulsion, the more fluid mass filling the cavities (which are
very small, 1-2 /x, in diameter), whilst the walls are composed of a
more viscous substance. Such an emulsion obeys certain well-known
physical laws, and the relation of the alveolar walls both to each
other and to the free outer surface can be theoretically defined.
Solid heterogeneous particles enclosed in the emulsion, if too large
to lie in the substance of the walls, are surrounded by a surface
film in which the alveoli are arranged, as they also are on the free
surface, somewhat like the cells of columnar epithelium. Move-
ments may occur in the whole mass, as the result of disturbances
in the surface tension of the superficial alveoli, and movements pro-
duced in emulsions in this way closely resemble the streaming and
other movements of protoplasm. The reticular
and filar' appearances are also to be attributed
to disturbances, due to causes, in the interrelation
of the alveoli, or they may represent the optical
section of the alveolar walls themselves.

Now it is quite possible to convince oneself
that such an alveolar structure does actually exist
in many cases, although, as Biitschli himself
admits, it is not always to be so identified. It
seems probable, however, that on the whole it
does represent truly the appearance of protoplasm
under certain (and commonly occurring) condi-
tions, but it also seems equally clear that these
conditions are not necessarily always fulfilled.
For it is essential for the production of such an
appearance that there shall be at least two non-
miscible fluids of different refractive index, and
if either of these conditions is not realised, or is
temporarily in abeyance, it will follow that the
alveolar appearance must also be absent or dis-
The foam structure appear. And we are acquainted with so many
2egaeriner.0t0plas * important series of changes in the relations of
the various protoplasmic constituents to each
other that it is hardly necessary to postulate the permanence of
those conditions of which an alveolar structure is the consequence.
Thus it would seem that an easy modus vivendi might be reached
which would render it possible, whilst recognising the heterogeneity
of the substances included under the generic term Protoplasm, to
admit that at one time an alveolar, at another a filar, or a reticular
appearance might occur. A fibrillar structure is certainly present
during nuclear division, and although the extreme adherents of the

FIG. 3.

THE STRUCTURE OF CELLS

alveolar theory see in the fibrils a honeycomb structure, the cavities
are generally admitted to be reduced to the vanishing point.

Strasburger has attempted to utilise both the filar and the
alveolar hypothesis, considering that in every cell the protoplasm
outside the nucleus consists of two distinct parts. The one, which is
specially nutritive and alveolar, he terms Trophoplasm ; the other,
which is more closely concerned with the dynamical changes in the
cell, and possesses a filar structure, he designates as Kinoplasm. The
relations of the kinoplasm will be more specially considered in
connection with nuclear division.

Besides the protoplasm and nucleus, there are present other
organised structures in the cell. The vacuoles, which have long
been recognised, are cavities in the protoplasm, and lined apparently
with a specialised layer of this substance. In some cases they are
rhythmically contractile as in many of the Protozoa.

But it is around that enigmatical body, the centrosome, that
especial interest has persistently attached ever since its first definite
discovery by Van Beneden in 1885. The centrosomes are minute
granules, most often situated either singly or in pairs in each cell,
and in close proximity to the nucleus. They are frequently con-
tained in a specialised mass of protoplasm, termed by Boveri the
Archoplasm.

Centrosomes and their attendant structures have been differ-
ently described by various observers. Van Beneden, to whom we
owe the first recognition of these bodies, distinguished, in the case
of Ascaris, a central granule, surrounded by two concentric areas, to
which he gave the names of medullary
and cortical zones respectively. Boveri
described in the cells of the same
animal a centrosome surrounded by a
lighter zone, from which it was definitely
cut off by a kind of limiting membrane.
Within the centrosome he further dis-
tinguished a central granule, the cen-
triole. The latter body divides before
the centrosome increases by fission.

In still other cases (e.g. in cells of the
testis of Salamander) various observers
(Meves, Driiner, etc.) have distinguished FIG. 4.

a whole Series Of Concentric ZOneS Ascaris megalocfphala. Schematic

j.i T J.T_ • i. figure of diaster stage of the first

arOlind the CentrOSOme. In the giant cleavage mitosis, c, centrosome ; m.z,

cells of the spinal cord and in leuco- (TftervZn Beneden.)' c°rtical z°ne<
cytes, Heidenhain has distinguished a

group of granules, which replace the single or paired one
more commonly met with, and in other cases again there is a
reticulate sphere (echinoderms) containing a varying number of

io THE STRUCTURE OF CELLS

granular inclusions. In plant cells centrosomes have been far less
often identified than in animals. They are more frequent, or at
least more easily demonstrable, in the lower members of the
vegetable kingdom than in the higher plants, in which they are
probably restricted to the motile sperms. The evidence for their
occurrence in angiosperms is not convincing. When present in a
cell, they usually occur in the form of a small granule enclosed in a
sphere, and are comparable with the centrosome and centriole of
Boveri. Strasburger has proposed the convenient term of centro-
sphere to designate the sphere together with its included granule,
reserving the term centrosome for the latter body only. It
is quite certain that the centrosphere apparatus presents itself
in varied degrees of complexity, not only in different organisms,
but even in different cells of the same tissues, and Strasburger's
term has much to recommend it, since, in spite of the large litera-
ture which has grown up around the subject, we are still mainly in
the dark as to the true meaning and relations of the different parts.
It seems clear, for example, that the centriole of Boveri corresponds
to that which by most writers has been called the centrosome,
and Boveri himself states that the division of his " centrosome " is
preceded by that of the centriole.

The centrosome or centrosphere is itself not unfrequently
enclosed in a denser mass of protoplasm, called by Boveri the
Archoplasm, and by Strasburger the Kinoplasm. Probably, how-
ever, appearances denoted by these terms are not the expressions
of permanent structures, but represent transient phases of cellular
activity. The structures thus called into existence may, however,
be, at least temporarily, very pronounced, since at least a part of
the achromatic figure, which is formed during nuclear division,
owes its origin to the archoplasmic mass. Nevertheless, the archo-
plasm (or kinoplasm) may become absolutely indistinguishable at
other periods in the life of the cell.

A far more difficult question to answer than that concerned
with the permanence of the archoplasmic or kinoplasmic structures
refers to the centrosome itself in a similar connection. Whilst
many authors have strenuously maintained its permanence from
one cell-generation to another, comparing it in this respect with the
nucleus itself, a considerable weight of negative evidence has never-
theless accumulated in the opposite scale. The striking relations
which obtain between the centrosome and the nuclear figures at
phases of division naturally produce a profound subjective impres-
sion upon the observer, and it has even been assumed that the
centrosome still persists, even when its actual existence cannot be
successfully demonstrated. There is no doubt that other granules
have frequently been mistaken for centrosomes, selected because
they happened to lie sufficiently near the spot where the structures

THE STRUCTURE OF CELLS

in question might have been looked for, and thus no little confusion
has been introduced into a subject already sufficiently bristling
with difficulty. But the cases of Acanthocystis (Schaudinn) and
of Actinosphaerium (R. Hertwig) show quite clearly that centro-
somes may, at least in the lower animals, be certainly differentiated
afresh in the cells from which they had previously been absent.

FIG. 5.

Aranthocystis acukata. A and B, for-
mation of the centrosome from nuclear
constituents in swarm-spores. C, resting
cell. D, nuclear division preceding fission.
(After Suhaudinn.)

The so-called Blepharoplast, which is associated with the male
reproductive cells of certain cycads and ferns, appears to present
very strong analogies with animal centrosomes, and yet the
blepharoplasts have not been seen in the antecedent cell-genera-
tions of the plants in Avhich they occur, and hence they have
almost certainly been formed de now. On the whole, then, the
question as to the relative permanence of the centrosomes through
the series of ontogenetic cell-generations must be left an open one.
Certain facts are, however, known which conclusively prove that
centrosome-like structures can be formed in cells from which, under

12

THE STRUCTURE OF CELLS

normal circumstances, they are absent. Morgan showed that
concentrated solutions of salts could induce the appearance of
centrospheres with radiations in the eggs of certain echinoderms,
and Loeb further proved that by adding magnesium chloride in
appropriate quantity to sea-water, the eggs of sea-urchins could be
brought into such a state that when replaced in normal salt water

FIG. 6.

Actiiwsphaerium eichornii. A and B, nuclear origin of the centrosome, which arises at one
end of the nucleus. C, D, further stages in the mitosis (A-D refer to the first polar mitosis).
E, diaster of a somatic mitosis, in which no centrosome is present. (After B. Hertwig.)

they underwent the normal embryonic segmentation. Wilson,
investigating the cytology of the process, confirmed the results,
and ascertained that the treatment caused the formation of centro-
spheres which seemed to direct the cell-divisions. And R. Hertwig
long ago showed that at least the early stages of a parthenogenetic
segmentation could be similarly induced by the action of strychnine.
Hence there is a considerable body of evidence to show that the
centrosomes are structures which, though physiologically the signs

THE STRUCTURE OF CELLS 13

of important changes in the protoplasm, are not necessarily
permanent organs of the cell. And a wide survey of the processes
of mitosis in the lower animals and plants serves fully to confirm
this conclusion.

The Structure of the Resting Nucleus.

It has already been said that it was not until the year 1875
that the nucleus was fully and universally recognised as an all-
important cell organ. Even as late as the previous year, Auerbach
published a treatise on its behaviour during cell-division maintaining
that it completely disappeared during the process, and he gave the
name of Karyolysis to the phenomenon in question. With the
recognition of the complex series of changes undergone by the
nucleus during division, and its obvious importance, in connection
with fertilisation, also discovered in 1875, it speedily formed an
object of serious study. And the investigations were not only
carried on in killed cells, but its behaviour during life, as well as
its chemical structure, presented attractive problems for solution.
The general outcome of these investigations is as follows : — The
nucleus is delimited from the cell protoplasm (the cytoplasm of
Van Bambeke) by a membrane which was regarded by Schwartz as
consisting of a substance called by him Amphipyrenin. In some
cases, however, it appears not improbable that the membrane is at
least partly produced from the cytoplasm, as a kind of precipitation
membrane, whilst in other cases, as for example in some of the
coccidia, Schaudinn has shown grounds for thinking that the so-called
chromatin of the nucleus itself may contribute to its formation.

Within the membrane the nuclear contents may be distinguished
as a matrix of a substance which stains with some difficulty, and
which forms a sort of meshwork within it. This is the Linin of
Schwartz, and seems to closely correspond with the plastin,
distinguished chemically by Zacharias. In addition to the linin
there exists a more fluid gelatinous substance, the Paralinin of
Schwartz. Imbedded in the linin are a large number of granules
which, by reason of their exhibiting a strong affinity for certain
dyes, were termed Chromatin by Flemming. The chromatin consists
of a highly complex nitrogenous substance, and always contains
phosphorus. Chemically it belongs to the class of proteid
compounds classed as nucleins, and by analysis can be made to
yield proteids and nucleic acid. In addition to the true nuclein
chromatin, there have been described other inclusions within the
linin known as Lanthanin (Heidenhain) or oxy- or basi-chromatin
bodies, which appear to be related to the nuclein series, and which
perhaps are complex, high-graded substances which can be built still
further up to true nucleins.

Most nuclei contain, besides these constituents, one or more

i4 THE STRUCTURE OF CELLS

masses, usually of a spherical or oval shape, known as Nucleoli.
These bodies long ago attracted the attention of investigators, and
it will be remembered that they were raised to a rank of con-
siderable importance by both Schwann and Remak. They usually
are easily stained, and thus were included amongst the chromatin
bodies of the nucleus, but subsequent investigation has shown that
they are, in many cases, widely different from nuclein. Two kinds
of nucleoli were distinguished by Flemming under the names of
eu- and pseudo-nucleoli respectively, the latter representing, at least
chiefly, aggregations of a substance which closely approximates to,
if it is not actually identical with, true nuclein. And more recent
investigations have tended to confirm the supposition advocated by
Zacharias, that the ordinary eu-nucleoli, so far from consisting of a
single substance such as pyrenin (Schwartz), are complex mixtures,
or else, at any rate, bodies which readily yield, by suitable treat-
ment, different substances of complex molecular composition. It is
true that the author just referred to arrived at the conclusion that
the nucleoli were destitute of phosphorus, but this view can hardly
be maintained, at least in all cases.

Investigations on the nuclei of Protozoa and of some of the
lower plants seem to have shown that these nucleoli consist of
at leas^ two groups of substances, the one consisting of, or
approximating to, nuclein, the other more nearly resembling the
linin, or even the cytoplasm, in its staining and other reactions.
At any rate, the chromatin, which forms so obvious a character in
dividing nuclei, appears in some cases, e.g. Actinosphaerium, to be
mainly derived from a nucleolar source. It is highly probable that
these bodies are really heterogeneous, and represent reserves of
complex materials which can be drawn on for various purposes
during periods of nuclear activity. For at such times the nucleolus
always undergoes considerable change, and is either completely used
up, or its remains fragment and pass out into the cytoplasm, where
their further fate is still obscure.

Whilst the nucleoli are thus losing substance they often exhibit
vacuolation, and even in resting nuclei vacuoles may sometimes be
detected within the nucleoli, pointing strongly to the correctness of
the hypothesis as to their heterogeneous nature.

A further point which deserves mention in connection with the
nucleoli is the view held by some writers (e.g. R. Hertvvig) that
they stand in some close relation to the centrosomes, and that the
existence of the latter structures may be traced back to a nucleolar
origin. Further, Strasburger, in his account of kinoplasm, has
suggested that the nucleolar substance may serve as the material
which stirs up the dynamical and metabolic activities latent in the
cell. On the whole, it is impossible, in the present state of our
knowledge, to ascribe any single function to these bodies, and the

THE STRUCTURE OF CELLS

evidence before us seems to indicate that just as they are very-
diverse in structure and composition, so also they may, and almost
certainly do, play very different parts in the general economy of
the cytoplasm and nucleus.

The resting nucleus may, then, be regarded as an organised
structure containing a considerable assortment of highly complex
and labile substances. But this very lability, itself a condition of
the profound and important changes which succeed each other with
extraordinary rapidity during the division of a nucleus, is bound up
in, or at least is related to, an organisation which directs and

Attraction-sphere enclosing two centrosomes.

Nucleus *

Plasmosome or
true nucleolus.

Chromatin-

nttwork.

T • • 1 •"*-• ' '•

Lmin-network. i^'J

Karyosomc or
net-]

Plastids lying in the
cytoplasm.

Vacuole.

Lifeless bodies (meta-
plasm) suspended in
the cytoplasmic reticu-
luiu.

FIG. 7.
Diagrammatic representation of the structures present in a typical cell. (After Wilson.)

determines that sequence of chemical and physical transformations
which so strikingly accompany the whole process. Moreover, there
is abundant evidence of the existence of a material exchange
passing between the nucleus and the cytoplasm which becomes
strongly marked at all periods of special cellular activity — such, for
example, as secretion, regeneration, and the like.

Nuclear and Cell Division.

The multiplication of the uninucleate cell is always preceded,
save in the lowest protozoa and protophyta, in which the details of
the processes are still obscure owing to the absence from them of

1 6 THE STRUCTURE OF CELLS

a well-defined nuclear body, by a division of the nucleus. This
may either take place in a simple manner, as was determined by
Eemak, or it may only be secured as the result of a complicated
rearrangement and fission of certain nuclear constituents. To the
former, or direct (Flemming), method of division, the termAmitosis has
been applied by Flemming, whilst the latter, or indirect (Flemming),
method was also termed Mitosis by the same author. The word
Karyokinesis (Schleicher) has often been substituted for mitosis, but
both terms are expressive of the same phenomena. Amitosis, in
the higher animals, is not of such generally widespread occurrence,
but in the lower forms it frequently appears as an intercalated
method along with a more or less complex form of ordinary
karyokinesis. It is also generally met with in nutritive gland cells;
thus in the follicular epithelium of the ovary, in the "foot " cells of the
testis, and in the tapetal cells of the higher plants, it is not uncom-
mon. In these cases it appears to be characteristic of degenerating
tissues, and this explanation has been extended to amitosis gener-
ally by Ziegler and vom Rath, but many instances are known in
which such a view is quite untenable. Thus, there is good reason
to believe, as Meves or others have shown, that in the ovary, cells
which ultimately are destined to give rise to ova may multiply in
this way, and Schaudinn, Siedlecki, and others have shown that in the
Sporozoa such amitotic divisions often follow shortly on the act of
fertilisation, and give rise directly to the new generation of parasites,
and again amongst Infusoria the macronucleus seems always to in-
crease in this way. Furthermore, Nathansohn proved, in the case
of Spirogyra, that by appropriate treatment with anaesthetics the
nuclei could be induced to divide amitotically, and that this amitotic
origin in no way influenced the conditions of the subsequent develop-
ment of the cells concerned, for these were capable of even pro-
ceeding as far as to form sexual cells, on the restoration of a normal
environment. But in comparing amitosis and mitosis together, the
advantage which the latter possesses, so far as can at present be
stated, seems to lie in the accurate quantivalent distribution of all
the structural elements concerned in the process between the two
daughter nuclei. Whether this is the only advantage, or whether
perhaps some mechanical or other factors are also involved, must be
left to the future to decide.

In considering the general phenomena presented by karyokinesis,
there are two sets of factors which, though closely interwoven in
the process, may with advantage be kept as distinct as possible.
For these changes involve the nucleus on the one hand and the
cytoplasm on the other, and the degree of complexity which each
of them may respectively assume is not necessarily invariable or
correlative, either in different organisms or in different tissues of
the same individual. A second, and not less important, considera-

THE STRUCTURE OF CELLS

tion arises in connection with the fact that nuclear- and cell- (or
cytoplasmic-) division are by no means invariably associated, and
that although the cytoplasm never gives rise to a number of cells
in excess of the number of nuclei present, its divisions in other-
respects may occur independently of that of the nuclei. This is
seen in the cleavage of some animal eggs (e.g. mollusca), in the
formation of endosperm in the seeds of angiosperms, in the develop-

FIG. S.

Lilium inartagon, prophase of the first mitosis in the pollen-mother-cell, showing the longi-
tudinal fission of the cromatin and linin.

merit of the eggs of Fucus and of the spores of Mucor. In all these
instinces, the division of the nucleus precedes that of the cyto-
plasm, which is only subsequently partitioned.

The first indication of approaching karyokinesis in an ordinary
somatic cell of the body of one of the higher plants or animals is
usually visible in the nucleus. The chromatin granules become
aggregated in lines, corresponding to a growing definiteness in the
delimitation of the linin. Thus from the generally granular appear-
ance, the character of a much convoluted and tangled chromatic

1 8 THE STRUCTURE OF CELLS

skein is produced. The linin framework does not necessarily form
a continuous thread. Often it is more or less broken, and it almost
always shows cross-anastomoses (from which, however, in the later
phases, the chromatin is commonly absent) with the neighbouring
threads. This anastomosis is doubtless the expression of its segrega-
tion, due to contraction ; the anastomoses themselves representing
the original meshes by which the substance was formerly bound
together into a coherent whole. Simultaneously the chromatin
increases largely both in amount and in the intensity of its stain-
ing power — a fact which may be taken to indicate a chemical or
physical change in its state. The linin thread-work that contains
the chromatin is often not scattered irregularly through the nucleus,
but is more or less polarised, as was clearly observed by Rabl, in
such a Avay as to converge, often with considerable distinctness,
towards one point on the nucleus. This point is occupied by the
centrosomes when they are present. At first usually lying in
pairs, and often in a mass of archoplasm, these bodies in the simpler
cases now commence to diverge, and each is either accompanied by
a portion of the original archoplasm, or else the latter is differenti-
ated progressively and afresh as they move apart to take up
diametrically opposite positions on the periphery of the nucleus.
From them radiate outwards into the protoplasm the well-known
astral figures which are characteristic structures in the cell at this
period, and are commonly regarded as of archoplasmic origin.

Meantime within the nucleus the chromatic thread thickens and
shortens. Some of its substance is probably derived, at least in many
cases, from the nucleolus, which becomes vacuolated and often
fragments about this stage. Finally, the thread breaks up into a
number of segments which is constant for the somatic cells of the
species. These segments are the Chromosomes (Waldeyer). At or
immediately following this stage a fibrillar structure begins to
appear within the nucleus, and as it increases the chromosomes are
gradually driven to occupy an equatorial position (the equatorial
plate stage) in the nucleus. What is precisely to be looked on as
the origin of these fibrils (the so-called achromatic fibres which
together form the achromatic spindle) is not certainly known.
Some, with Strasburger, hold that they are exclusively of cytoplasmic
(kinoplasmic) origin, growing inwards, as it were, from the polar
centrospheres. Others again look on them as derived from nuclear
substance, whilst a third view regards them as of mixed origin.
Probably the last view is less open to objection than the other two.
The fibrillar structures themselves are almost certainly the result
of conditions of stress and strain in the viscous substances of which
the cell is composed, and it would appear probable that any sub-
stance capable of assuming the fibrous character might be compelled
to do so. And there is abundant evidence to show that such sub-

THE STRUCTURE OF CELLS

stances do exist in the nucleus, as they certainly do in the cyto-
plasm. For in the case of, e.g., the micronuclei of infusoria, the
whole spindle is entirely intra- nuclear, the cytoplasm apparently
not furnishing, at least directly, any part of it.

With the congregation of the chromosomes to form the
equatorial plate, the first stage or Prophase of division terminates.

The equatorial plate, or aster, stage is often one of relatively
long duration ; so much so that it may even happen that some of
the signs of cytoplasmic activity may fall into temporary abeyance.
For example, the astral radiations outwards from the centrosomes
may cease to be visible at this stage (e.g. in Pellia), though they

FIG. 0.

Stages of the mitosis in the micronucleus of Paramorclvm,
liowing the "pole plates"; true centrosomes are not present.

Affill- T? Uuft-lltir, \

(After R. Hertwig.)

reappear later on. The nuclear wall commonly, though not
always, disappears whilst the chromosomes are collecting at the
equator, and the nucleolus or its fragments, if they have not
previously disintegrated, now are no longer recognisable.

The individual chromosomes often, but by no means always,
assume the shape of a V, with the apex turned centrally in the
equatorial plane. Each one is supported by fibres of the achromatic
spindle which run from the poles, and terminate on the chromosomes
at the equator. The chromosomes next split longitudinally, and
this partition forms the commencement of the stage known as the
Metaphase. The two daughter halves rapidly diverge, being guided
by the spindle fibres towards the poles. During their divergence

20

THE STRUCTURE OF CELLS

Hi

^x

'tW

1 * TvV '
H_>^^

• <m\

>i^»P -• -yjj :y ^^^

" ,^ 'J^^^L--* - c^^

.r^a^

•-' vy^iv.rxr-)

vs/ r^p M1---'

FIG. 10.

FMCUS vesiculosus, stages in the first mitosis in the fertilised egg (oospore). A-D, Prophase ;
E, commeucement of the Metaphase.

THE STRUCTURE OF CELLS

21

/fc-Wfri

FIG. 10 (continued).

F to: us vesiculosiis, stages in the first mitosis in the fertilised egg (oospore). F, Metaphase ;
G, H, Anapliase.

THE STRUCTURE OF CELLS

fresh fibres are differentiated between the retreating groups of
halved chromosomes, and form the interzonal fibres (Verbindungs-
faden of the German writers). Whether these play any mechanical
part in forcing the daughter chromosomes apart is uncertain, as is
also the r61e assigned to the above-mentioned fibres that appear
to direct the chromosomes towards the poles. Probably the latter

• mK^^ ^

r^^|||)f:^/ 1

FIG. 10 (continued).

/"KCJIS vesicttlosus, stages in the first mitosis in the fertilised egg (oospore). 7, Telophase.
(Phil. Trans, of the Royal Society.)

are actively contractile, and there is some evidence to show that the
interzonal fibres are in a state of stress. In some instances, e.g. in
fertilised and segmenting eggs of Fucus, the arrangement of the
elongated plastids in this region plainly indicate such a condition of
stress or strain. But the achromatic apparatus varies considerably
in the degree of its complexity, and it probably would be unsafe to
attempt to assign constant functions to its constituent parts. So
much, however, may be said, that the chromosomes appear to be

THE STRUCTURE OF CELLS

passively moved to their respective poles, and to possess no power of
automatic movement of their own.

With the arrival of the chromosomes at their respective poles
the Anaphase stage supervenes. This consists practically in a
series of regressive changes which leads to the formation of normal
resting nuclei. The chromosomes lose their sharp outline and
swell up ; at the same time the nucleoli once more reappear. The
chromatin, or as much of it as persists, is distributed through the
swollen linin just as it originally existed in the parent nucleus, and
finally a wall isolates the daughter nucleus from the surrounding
cytoplasm. But the cytoplasm still bears traces of recent dis-

Fio. 11.

Pelvetia canaliculata, telophase ot
the second mitosis in the fertilised
egg (oospore). (Phil. Trans, of the
Royal Society.)

turbances, and the period of gradual restoration of quiescence in it
forms what is sometimes known as the Telophase.

The centrosome (when present) is often already doubled during
the meta- or ana-phase, but the astral radiations frequently do not
die away till much later. It is in the region of the interzonal
fibres that events of the greatest interest are now proceeding. In
animal tissues it very often happens that the two cells are constricted
equatorially, and they may ultimately become delimited from each
other, the remains of the interzonal fibres then remaining at this
spot, where they may be long recognised as the Intermediate Body.
In plants, owing to the existence of a cellulose skeleton, and the
close adherence of the cytoplasm to its internal surface, such a con-
striction does not usually arise. Instead of this the fibres increase

THE STRUCTURE OF CELLS

greatly in number, especially in the equatorial zone. In these
fibres the primordium of the new cell-wall is laid down, in the first
instance as a viscous film, but which later, by the deposition of fresh
substances, becomes converted into the cellulose partition. Its
mode of formation is interesting because reasons have been shown
for supposing that some at least of the protoplasmic connections
between adjacent cells are primarily effected by the permanence of
such continuity through the membrane during its formation.

FIG. 1-2.

Diagram of the successive stages of a nuclear division.
A, spirem, with the fission of the chromatic linin. li, aster.
C, D, K, separation of daughter segments. F, reconstitution
of daughter nuclei. (After Flemming.)

It may, however, happen that no membranes are formed in the
interzonal fibres, such as will serve to delimit the daughter cells
from each other. A complete series can be traced between the two
extremes. Thus in the first division of the spore-mother-cell of
Fegatella (Fig. 13), a cell plate is laid down, but not completed, and
it is not until after the next nuclear division that this wall (which
has shifted its position in the interval) becomes part of the final
partitioning membranes. Again, in the endosperm of seeds, some-
times the embryosac is transversely divided after the first karyo-
kinesis, but far more commonly a large number of nuclei are first

THE STRUCTURE OF CELLS

formed. These then take up their final positions, and a new set of
interzonal fibres are differentiated between them, and in the
equatorial planes of these groups of fibres the cell-walls are laid
down. And finally, in other cases the cytoplasm may divide into
masses containing either single or several nuclei, and secrete
membranes without the intervention of interzonal fibres at all.

It will have become evident from the foregoing account of the
relation between the nucleus and the cytoplasm, that these two
principal constituents of
a cell retain to a consider-
able extent a separate
individuality, at any rate
in the higher forms. This
separate nature only be-
comes obscured at periods
of division, but even here,
as has been seen, the
essential boundaries are
retained through all the
changes connected with
fission and redistribution.
Thus it is legitimate to
regard the cell nucleus
as an entity which does
not arise de now. The
nuclei of successive cell-
generations are lineal
descendants of an ances-
tral nucleus, just as the
cells of the present day
owe their being to the
multiplication of ante-
cedent parent cells.

The nucleus, how-
ever, does not stand
alone amongst the cell

constituents as only arising by multiplication by fission of pre-
existing structures of a similar character. In the plant-cell the
various plastids originate in a similar manner, and there is no more
evidence to show that they can be differentiated afresh from the
general cytoplasm, than that the latter, by spontaneous generation,
can arise de now from its elemental constituents. The same is true
for the curious coloured plastids known as Zoochlorella in animals,
which possibly represent species of algae imprisoned in the cells of
their animal hosts, or perchance, though less probably perhaps, they
may be regarded as more akin to the chlorophyll corpuscles of the

D

FIG. 13.

Fegatella cemica, the division of the spore-mother-cell
into four cells, showing the change in position of the
first formed wall.

26 THE STRUCTURE OF CELLS

plant cell. The latter hypothesis would be difficult to sustain in
the absence of a series of forms through which their evolution
might be traced, whilst, on the other hand, the symbiotic relation-
ship existing between fungi and algal cells in a lichen strongly
supports the presumption that an analogous case is furnished by the
Zoochlorella organism and its host.

" Reduction Divisions"

Few cytological discoveries have aroused more widespread
interest than that of the periodical recurrence of the so-called
" Reduction Divisions," which are intercalated at some point in the
cell-generations intervening between two consecutive sexual unions.
Each uniting gamete or sexual cell contains in its nucleus only
half the number of the chromosomes that will be characteristic of
the embryo resulting from their fusion, and will be retained
throughout its cell -generations up to those which lead in their
turn, more or less directly, to the production of spermatozoa and
mature ova. This remarkable phenomenon has been observed in
all the animals and plants which have been carefully studied, with
the exception of the more lowly or primitive forms in which the
nuclear history is but imperfectly understood.

The phenomenon in question was first made known by the
investigations of Van Beneden in 1883 and 1887 on Ascaris. The
choice of this animal was in some respects perhaps not very
fortunate, since it does not exhibit the process in a very typical,
but rather in an extreme, form, and thus a certain amount of
misapprehension prevailed at one time respecting it. Since that
period, however, very numerous animals and plants have been
studied, with the result that the phenomenon is proved to be of
very general occurrence, though differing considerably in detail in
the various organisms.

At first, and perhaps naturally, the view was advanced that the
reduced number was secured through the mere degeneration and
consequent elimination of the superfluous chromosomes, but it gradu-
ally became clear that the evidence was entirely opposed to such a
simple explanation, and that, on the contrary, the reduction was
only arrived at after an exceedingly complex rearrangement of the
nuclear constituents. It would, however, be going too far, as will
subsequently appear, to deny that any nuclear substance is lost :
all that can be said is that it is certain that no chromosomes, as such,
are normally eliminated.

In attempting to trace the sequence of events, it must be borne
in mind that the process is evidently one of the highest importance,
seeing that it occurs alike in animals and in plants, and this
importance is increased rather than lessened by the further

THE STRUCTURE OP CELLS 27

recognition of the fact that the reduction may occur at morpho-
logically diverse stages in the life-history of the various organisms
— a fact which clearly emphasises its profound physiological sig-
nificance. But although there is no lack of hypotheses to explain
it, no one as yet has given a satisfactory theory which will
embrace the whole range of the phenomena concerned.

In the higher organisms the process of reduction appears
invariably to be closely bound up with two nuclear divisions which
rapidly succeed each other, and are hence often spoken of as the
Reduction Divisions. These differ in some important respects from
those characteristic of other mitoses. They can only be con-
sidered in outline here, and after premising the existence of a not
inconsiderable diversity as to the details of the process in different
organisms. In animals the mitoses in question only occur in direct
relation to the formation of the sexual cells or gametes, but in
plants it is more usual to find a greater or less number of cell-
generations follow on the Reduction Divisions before the actual
gametes are formed. Thus it becomes obvious that the formation
of sexual cells is not a necessarily immediate consequence of the
change in the nucleus.

If the course of events be studied in an animal, it is seen that
in the development of the spermatozoon and of the mature egg, a
strictly comparable series of changes is passed through. Just as
the spermatocyte gives rise, by two successive bipartitions, to four
sperms, so the immature ovum, by means of two successive nuclear
divisions, gives rise to four potentially fertilisable eggs, of which,
however, three commonly degenerate and are known as the polar
bodies.

The nucleus of the spermatocyte, just as does that of the im-
mature egg (which may be distinguished from the ripe egg by
the name of oocyte), goes through a somewhat prolonged period of
growth before entering upon the critical mitoses, As these two
divisions are marked by certain peculiarities from those of the
other cell-generations, it is convenient to designate them by special
names.

The first may be termed the Heterotype, the second the
Homotype, mitosis, following the terminology introduced by
Flemming. During a large part of the growth -period, leading
directly to the heterotype division, the nucleus cannot be correctly
described as resting, for the linin reticulum is plainly discernible, as
also are the regularly arranged chromatin granules, which serve to
render it distinct. In fact, this prolonged spireme is highly
characteristic of the heterotype mitosis, as contrasted with those
which have been previously gone through. It is during this stage
that the fission of the chromatin granules occurs, as was first seen
by Pfitzner in 1881. Each granule becomes drawn out into a

28

THE STRUCTURE OF CELLS

dumb -bell -shaped body, and finally two rows of granules are seen
to occupy the margins of the flattened linin riband.

This stage is often (Salamander, Helix, Lilium, etc.) followed by
a more or less complete longitudinal fission and separation of the
linin riband, each half now containing, at least at first, a single row
of chromatin granules. It is perhaps not improbable that a similar
process also occurs during the corresponding stage of somatic

\

FIG. 14.

Lilium martagon, prophase of the first mitosis in the pollen-mother-cell, showing tlie longi-
tudinal fission of the chromatin and linin.

mitoses, but the shortness of its duration in the latter renders the
process difficult to observe. At or about this period a remarkable
contraction of the chromatic linin filament occurs, and commonly
the nucleolus is included in the tangle. To this stage the name of
Synapsis (Moore) has been given, and it seems to represent an
important step in the process, and one which is confined to this
first (heterotype) reduction division. After the synaptic condition
is over, the linin, which has been getting richer in chromatin, is
usually seen to be shortening, and at the same time thickening, but

THE STRUCTURE OF CELLS 29

it may happen that the subsequent events become much obscured,
the filamentous arrangement of the linin and chromatin ceasing to
be distinctly recognisable.

Up to this period there is, on the whole, a general agreement
as to the nature and sequence of events, but the subsequent
changes have been very diversely described and interpreted in the
case of different organisms.

In the most favourable cases the parallel arrangements of the
chromatin granules and of the split linin thread can be followed for
some time during the shortening and thickening of the filaments.
Brauer has described, for the spermatocytes of Ascaris, a second
longitudinal fission in each chromatic filament, resulting in the
production of four rows of chromatin granules from the single row
originally present in the primitive thread. A similar event has
been stated by some to occur in the corresponding division in the
pollen-mother-cell of a lily. In the majority of instances, however,
the chromatic linin is seen to contract and thicken, and all traces
of the fission may become unrecognisable. Finally, the chromatin
comes to be aggregated in definite parts of the band, the intervening
portions being occupied by colourless linin. There are often, also,
cross anastomoses of the same substance between neighbouring
strands. The chromatic areas in question mark the position of the
developing chromosomes (Fig. 15, A), which gradually become
more definitely isolated from each other. And they are seen to
be present in half the number characteristic of all the preceding
nuclear divisions in the organism. Once more each chromatic band
exhibits a split x along the whole or greater part of its length, and
this marks the line along which, later on, the cleavage of the
chromosomes in this (heterotype) mitosis will be effected. In many
cases, as is especially well seen in amphibians (Fig. 15, B, C), the
fission of the young chromosome is incomplete and the sides diverge,
thus causing the whole to assume the form of a closed ring. In
other instances, howeA'er, the fission is completed, and the two
halves, lying in close juxtaposition, may exhibit a complex series
of figures which demand much care in their elucidation.2

1 It is commonly assumed that this split represents the original longitudinal
fission of the linin filament. It is not, however, proved beyond doubt that this is
invariably the case.

- These appearances have, however, been differently explained by some investi-
gators ; thus some have seen in them evidence of an approximation of two entire
somatic chromosomes, hence when the apparent halves separate to give rise to the
chromatic part of the daughter nuclei, it would follow that what has really
occurred is the distribution of half the original entire somatic chromosomes to the
daughter nuclei. That is to say, the division might be regarded as qualitative as
well as merely as quantitative. And it will be evident on reflection that the same
result might be reached as the result of various analogous interpretations of the fore-
going processes, especially when the difficulties of investigation that occur during the
synaj'tic tangle are borne in mind

THE STRUCTURE OF CELLS

But the evolution of the chromosome does not always follow
along these lines. In a number of instances, exemplified by many
arthropods (e.g. Cyclops), after the early chromatic fission has been

Salamander, Heterotype mitosis in the spennatocytes. (After Moves.) For explanation of
the figures see the text.

passed. ^through, and the number of the future chromosomes has
been marked out, these bodies, it is true, may form rings
(Gryllotalpa) or parallel rods (Cyclops), but the chromatin, instead
of being tolerably equally distributed throughout the length of the

THE STRUCTURE OF CELLS 31

longitudinal halves, becomes specially aggregated at two spots in
each. Thus are formed the so-called Tetrads, to which much im-
portance has been attached in the theoretical interpretation of the
whole process of reduction. For it is thus seen that in the above
cases the tetrad may be regarded as having originated first by a
longitudinal fission of the chromosome rudiment, and then by a
transversely isolated aggregation of chromatin in each half.

It may also happen that tetrads are formed in a manner less
easy to follow out, as in Helix and in Arion, in which the separate
filaments are difficult, if not impossible, to trace in the stages
immediately preceding their formation ; the chromatin thus appear-
ing, so to speak, to travel to and become aggregated at definite
areas, and to assume in a somewhat irregular manner the ring form
of tetrad, similar to that occurring in Gryllotalpa, as described and
figured by vom Rath.

Still another type of tetrad formation has been described by

FIG. 1U.

Diagram illustrating tetrad formation. A, the split thread (spirem) stage. /?, later stage,
showing aggregation of chromatin at each end of the split bivalent chromosomes. C', fully
formed tetrads, of which the one to the right represents the most typical form.

Brauer as occurring in the spermatogenesis of Ascaris megalocephala
already alluded to above. The lining filament first contains a single
row of chromatin granules, each of the latter divides crosswise into
four, which lie in the same transverse plane, and hence the original
filament now contains four rows of chromatin granules. As the
process of shortening and thickening progresses, these become, so
to speak, telescoped together, and the end view of each filament
exhibits four chromatin masses corresponding to the four rows
just described, and which thus appear as tetrads similar to those
of Cyclops, although they would appear to have a very different
origin. For whereas in the latter case the single units of the
tetrad have arisen as the consequence of two longitudinal fissions
of the original chromatin granules, in the case of Cyclops the same
appearance is apparently produced partly by a longitudinal fission,
and partly by a transverse delimiting of the original granules. In
the first maturation division of the egg of the same animal, each
chromosome is seen to be divided completely into four segments,

32 THE STRUCTURE OF CELLS

though it is not certain as to whether the details of their develop-
ment are similar to that of the spermatogenetic tetrads as described
by Brauer.

Meanwhile, other changes have been proceeding, both within
and without the nucleus. The nucleolus commonly can be seen to
lose substance during the growth of the chromosomes, as is testified
by its vacuolated appearance. Often it fragments into smaller
particles during the prophases. But it has been definitely ascer-
tained, in many cases, that some part of this body is cast out into
the cytoplasm where it degenerates, and it is not improbable that
this will prove to be of very general occurrence. The possible
significance of this event ought not to be overlooked in view of its
striking occurrence in the lower forms of life, for it is in them that
the clue to the meaning of the complex changes observed in the
higher animals and plants must probably be sought.

In the cytoplasm, also, remarkable changes connected with the
centrosome and spindle mechanism have been proceeding. The
latter reaches very different degrees of completeness in different
organisms, and, as has been said on a previous page, even in the
different cells of the same organism. In the simplest case the two
centrosomes, when present, diverge and form a spindle not dis-
similar from that already described for somatic nuclear division.
In other instances (e.g. in Salamander) the two centrosomes diverge
tangentially to the nucleus, and the spindle is formed between
them, and, in the first place, without immediate reference to the
nucleus. Later on, however, from the poles of the central spindle
thus differentiated not only do the radiating fibrils reach into the
protoplasm, and even to the periphery of the cell, but there are
also others that extend to the nucleus and become attached to the
chromosomes. The latter are thus, as it were, roped up and pulled
on to the periphery of the first formed spindle (Fig. 15, D, E).
Almost every gradation occurs between the extreme forms here
sketched, and the matter seems to be essentially one of more or
less complete division of labour between the constituent parts of
the achromatic spindle *regarded as a whole. In the Salamander,
and those other cases in which it appears in a more or less complete
form, the central spindle seems to function as a sort of support to
keep the two poles apart, and to serve as a sort of railroad along
which the daughter chromosomes can be pulled along by the con-
tracting peripheral or mantle fibrils that attach them directly to the
poles.

In the divisions of the higher plants, as has already been ob-
served, no centrosomes have been identified with certainty, and the
spindle at first starts into existence quite irregularly. It speedily,
however, becomes for the most part bipolar, although not unfre-
quently isolated fragments of extruded nucleolar substance exert a

THE STRUCTURE OF CELLS 33

very obvious influence on the direction of individual fibrils which
may deviate towards and even terminate upon them.

When the chromosomes have reached the equator of the spindle
they may still preserve the form of rings, tetrads, or more complex
shapes, and the method of their fission which leads to the severance
of the daughter chromosomes is seldom so clearly longitudinal as is
the case in a somatic mitosis. The rings present the greatest
difficulty, and there exists a considerable divergence of opinion as to
whether their division really corresponds to a transverse or to a
longitudinal fission of the whole chromosome. The answer practically
turns on the conclusions arrived at as to the path of development
followed by the chromosome during the earlier phases ; i.e. whether
the plane of separation really corresponds to that of the cleavage of
the granules, or whether it may not be related to a totally different
series of events, and marks the separation of originally bivalent
chromosomes as is contended by some observers. In the latter case
the complete identity of all the parent somatic chromosomes would
be preserved in spite of its apparent loss through the fusion of them
in pairs. The separation of the daughter chromosomes would be
thus interpreted as not due to the fission of one, but as the segrega-
tion of each individual of a pair which had previously become
temporarily united.

After the separation of the daughter chromosomes and the com-
pletion of the anaphase (Fig. 15, G) and telophase, the two nuclei
which are thus formed commonly commence immediately to divide
once more. Again the reduced number of chromosomes reappears,
but the character of the process superficially resembles a somatic
mitosis much more closely than the preceding heterotype division,
and for this reason the name of homotype was given it by Flemming.
In reality, however, there are many other points of difference,
besides that of the reduced number of chromosomes. The first,
and perhaps the chief, peculiarity lies in the fact that there is good
reason for believing that the line of fission of the chromosomes is
always predetermined during the prophases of the preceding, the
heterotype divisions. This is strikingly seen in the case of Ascaris
eggs, in which, during the first maturation division, two of the four
rods that together represent one chromosome are distributed to
the daughter nucleus as the equivalent of a single daughter chromo-
some, whilst at the second mitosis each chromosome emerges as a
double (not quadruple) body, and at the metaphase the two con-
stituent or collective parts separate from each other as the definitive
chromosomes of the next (and final) nuclear generation. Essentially
the same course of events obtains in cases of tetrads.

When these divide at the equatorial plate the resulting dyads
thus formed retreat as the daughter chromosomes, and on the rapidly
following homotype division the dyads again reappear in the early

34 THE STRUCTURE OF CELLS

stages and divide at the equator, each half (monad) forming a
daughter chromosome.

And an essentially similar condition obtains in at least many
other more obscure instances. Thus in Salamander and in Trades-
cantia, chiring the dyaster condition of the anaphase of the hetero-
type, each daughter chromosome is seen to be longitudinally divided
(Fig. 15, F). This almost certainly is the result of the reopening of
a split formed during the prophase of the heterotype, but which has-
escaped recognition in many cases owing to the great difficulties
which these earlier stages present in their investigation. And the
fission, thus obvious in the dyaster of the heterotype, provides the
daughter chromosomes for the next (homotype) mitosis.

It is thus seen that these two mitoses, the heterotype and the
homotype, which in animals are the immediate forerunners of the
differentiation of the sexual cells, are clearly distinguishable from
the preceding ones in several important respects.

1. The appearance of the chromosomes in the reduced number,
i.e. they are only half as numerous as in the rest of the nuclei.

2. The long duration of the prophase, and the complex changes
and rearrangements, including, probably universally, a preparation
for the distribution of daughter chromosomes not only for this but
also for the succeeding division.

3. The remarkable forms assumed by the chromosomes upon
the spindle.

4. The very general extrusion of nucleolar substance, in rela-
tively large quantities, from the nucleus during the prophase.
Although probably of importance, it would be as yet premature to
speculate on the precise weight to be attached to this phenomenon,
but it is suggestive when considered in relation to the course of
events described for protozoa.

The accompanying figure may serve to render clearer the exact
nature of the different views which have been held as to the nature
of the processes which are passed through in the reduction divisions.
The somatic cell (I. in the figure) is supposed to include two
chromosomes, and below are represented, diagrammatically, the
various alternative phases gone through during reduction, the
corresponding stages being shown in any four figures on the same
horizontal line. The series II. and III. represent the events which
may be passed through on the assumption of the permanence of the
chromosomes, whilst the series IV. and V. correspond to those in
which such a permanence is denied. In the former case the two
original chromosomes, A, B, remain temporarily united, and their
two methods of possible separation are respectively shown. In
IV. and V. no continuous identity is claimed for the chromosomes,
and the two original ones are replaced by a single new one (C).

Considerable difference of opinion exists, then, as to the real

THE STRUCTURE OF CELLS

35

nature, as well as the- meaning of the events which are thus bound
up with the two divisions under consideration. The indications

Fir,. 17.

• Diagrams of Heterotype and Homotype mitoses to illustrate the various possible ways of
interpreting the chromosome distribution.

afforded by the constancy in number of the chromosomes through
the cell-generations of an organism point to a morphological per-
manence, and it has been argued that the same chromosomes re-
peatedly are re-formed at each mitosis.

36 THE STRUCTURE OF CELLS

And since, during the reduction division, there is no evidence of
the elimination or degeneration of any chromosomes, it is further
urged that each of the apparent units appearing in the prophase
of the heterotype division are really bivalent, and represent two
chromosomes joined end to end, but otherwise behaving as one.
Hacker, who has ably supported this view, believes, in common
with many who share it with him, that the tetrad is to be thus
explained. The longitudinal fission which divides the bivalent
rudiment of the chromosome is succeeded by a more or less trans-
verse separation or isolation of the chromatin, which marks the
fourfold character of these chromosomes. Consequently each
tetrad really represents not one but two chromosomes, and whilst
the first (heterotype) division corresponds to the line of longitudinal
cleavage, the second (homotype) separates and distributes actual
entire chromosomes. Hence it is supposed that a real distribution
of entire and diverse chromosomes occurs at the homotype mitosis,
whilst the heterotype is essentially similar to a somatic division,
and the reduction in number (due to the coherence in pairs) of the
chromosomes is only an apparent one. If it could be universally
proved to be true, such an explanation would account for many of
the remarkable peculiarities which, as has been seen, characterise
these divisions, besides affording a very strong support to the
theoretical views as to the nature of the mechanism of inheritance
advanced by Weismann. But the apparently well-established belief
that in other cases the preparation for the two divisions is accom-
plished by means of two longitudinal divisions of the chromatic linin
militates strongly against conceding the value of a general inter-
pretation to the views just sketched in outline. And moreover the
facts of amitosis as known to occur in some instances, also, though
in a somewhat different way, tell against the permanence of the
chromosomes, and consequently against the theories which have
been founded on that hypothesis. On the whole, the facts at present
before us rather tend to support the view of the brothers Hertwig ;
according to them the real significance of the process lies in that
sudden quantitative reduction of the chromatin which is a necessary
consequence of the rapid succession of the two mitoses in question.

It has already been pointed out that the reduction divisions are
a common feature to both animals and plants. In the latter, how-
ever, there appears to exist a much greater latitude as to the point
in the life- history at which they occur. In all the archegoniate
series of cryptogams, which includes the mosses, hepaticae, and
vascular cryptogams, as well as in all the flowering plants, the re-
duction divisions are not immediately connected, as they are in
animals, with the formation of the sexual cells, but with the asexual
spores from which the generation bearing the sexual organs arises.
Thus, after the homotype (or second) division, an indeterminate

THE STRUCTURE OF CELLS 37

number, which may be very considerable, of cell-generations inter-
venes between the division in question and the differentiation of the
sexual cells. It is true that, as in some of the flowering plants
(the embryosac development of the lily, for example), the divisions
giving rise to the four spores may be omitted, but the characteristic
features of the heterotype and homotype mitosis reappear, although
thus postponed, in the first divisions of the nucleus of the embryosac
(macrospore). This indeed is a fact of the utmost importance, as
emphasising the physiological necessity of the process ; just as it in
all probability (from its community to animals and plants) pre-
ceded current morphological differentiation, so now if necessary it
can override morphological limitations, or at any rate it is not bound
up with them.

Amongst the lower plants the facts have been tolerably com-
pletely elucidated in the case of Fucus, an alga in which asexual
spore -formation does not occur. The nuclei of the plant possess
the double (somatic) number of chromosomes until the formation of
the sexual organs. The oogonium gives rise to oospheres (typically
eight, though some may degenerate) by these nuclear divisions.
Of these, the first two are respectively heterotype and homotype,
and follow on each other with great rapidity, the last mitosis not
occurring till after an interval of rest.

In some of the desmids, and probably also in Spirogyra, there is
evidence to show that the reduction divisions, on the other hand,
occur not at the close, but at the beginning of the life-history, with
the first segmentation of the fertilised oosphere. But in the
majority of these lower organisms information of a precise char-
acter is still lacking on the matter. And until our knowledge of
the corresponding processes in the lower animals and plants becomes
much more complete than it is at present, we can scarcely expect to
solve the problem as to the utility or the necessity of the complex
events connected with the reduction divisions.

Although the higher animals and plants exhibit considerable
diversity amongst themselves in the series of changes passed
through by the nucleus in division, as well as in the relationships exist-
ing between the cytoplasm on the one hand and the cell-wall on the
other, they nevertheless agree for the most part in the broader out-
lines. The points of similarity are, on the whole, more striking
than are the differences, and the latter can often be referred with-
out much difficulty to unimportant deviations from a common ground-
plan. But although this is the case, the actual meaning of the
phenomena, as well as their phylogenetic origin (if there be one),
can hardly be grasped or explained by a reference to these forms
alone. It is in the study of the lowest forms of life that the key
to the solution of cytological problems may be sought for with the
greatest hope of success, for amidst the striking diversity exhibited

38 THE STRUCTURE OF CELLS

in them an analysis of the processes may render it possible to dis-
tinguish between the essential and what is merely accessory, and
may indicate the mode and directions in which the structures
characterising the higher plants and animals have been elaborated.
The essence of the type may perhaps be most clearly gathered from
a consideration of the deviations from it. Nevertheless, one is
confronted at the outset with difficulties. For although the nuclei of
many protozoa are apparently extremely simple, yet in the details of
their division they may exhibit considerable complexity, and this not
by any means always in the direction followed by the nuclei of higher
organisms. And conversely, nuclei are not seldom met with in
these low organisms which surpass those of the metazoa and meta-
phyta in differentiation, whilst in mitosis they are commonly simpler.

The features which seem to be common to all nuclei are — (1) the
existence of chromatin in some form or other ; (2) a matrix in which
the chromatin is imbedded, but which in the simplest cases may be
indistinguishable from the ordinary cytoplasm. Furthermore, the
fission of the chromatin is a common, perhaps invariable, antecedent
to nuclear division, but it is often difficult to ascertain, and may
possibly be really absent in some cases ; for example, in many amitotic
divisions.

The subsidiary structures, amongst which the centrosome stands
pre-eminent, can only be rightly appraised when their origin has
been traced in the lowest forms, in which various bodies which
appear to possess functions analogous with those credited to
centrosomes have often been distinguished.

As regards the occurrence of nuclei in the Protozoa and the
simplest plants, the investigations of recent years have tended to
reduce the number of those from which nuclei were formerly
believed to be absent, and at the same time it has become evident
that the structure in question may be present in very different
degrees of completeness. Thus in Chromatium, and probably in
bacteria generally, it is not possible to speak of the existence of a
definite nuclear body, but granules which on good grounds have
been identified with chromatin are to be distinguished in the
protoplasmic framework of the cell. In the cyanophyceae also
similar granules are visible, but are restricted to a definite
specialised part of the cell-protoplasm, although the latter cannot
be spoken of as a nucleus. In many of the forms which possess
scattered chromatin granules there is visible in the cell a body
which is obviously connected with the mechanism of chromatin
distribution, for on cell-division the granules of the latter congre-
gate around the central body, which sooner or later divides, each
half carrying with it half the chromatin, in the form of attendant
satellites, to each daughter cell. In some organisms, e.g.
Tetrainitus, the granules are distributed through the cell-

THE STRUCTURE OF CELLS

39

protoplasm in the periods intervening between two fissions, and are
only intimately associated with the central body at the time of cell-
division ; in others again, e.g. Chilomonas, they remain constantly
grouped in the vicinity of the body to which reference has just
been made. No structure has been certainly made out in it, but it
has often been compared to, or identified with, the central body
present in many of the more highly differentiated Protozoa, such as
Euglena, and it has further been likened to the nucleolus and also
to the centrosphere of those cells in which these structures have

FIG. IS.

Tetramitus. A, resting cell.
B, early phase of division, c.ft,
central body ; ch, chromatin
granules. (After Calkins.)

been found to occur. Indeed, it would seem that there is at least
some justification for the latter comparison, inasmuch as it appears
at least to discharge functions somewhat similar to those performed
by the centrosome though in a very rudimentary degree.

A distinct advance in differentiation is reached when the
chromatic and other constituents of the nuclear apparatus are not
only aggregated together, but are also delimited from the rest of
the cytoplasm by a wall or membrane. The degree of individuality
thus obtained provides a condition favourable to further special-
isation, but it seems clear that at any rate the linin framework in
which the chromatin is imbedded may be fairly traced back to a

THE STRUCTURE OF CELLS

true cytoplasmic origin, however much it may have become modi-
fied or altered under more special conditions. The chromatiri in
these primitive nuclei is often aggregated into clumps as in Actino-
sphaerium, Noctiluca, Coccidium, etc., or even concentrated into one
mass as in Actinophrysand Spirogyra. These masses have been termed
nucleoli by some writers, but recent investigations tend to show that
they really represent composite structures which contain other
substances in addition to chromatin. In coccidia, for example,
Schaudinn and others have shown that, although the chromosomes
are derived from them, there exists over and above the chromatin
a considerable mass of substance which is left behind after its exit,
and much the same is seen in Amoeba hyalina. Possibly their
analogues may be sought in certain of the so-called pseudo-nucleoli
of the higher organisms, or in those occurring in the nuclei of
Spirogyra, where it has been repeatedly asserted that the chromo-
somes originate from the nucleolus. As regards the origin
generally of the chromosomes and of the peculiar features exhibited
by them during mitosis, there seems but little doubt that they have
arisen through stages like those seen in tetramitus and chilomonas,
in which the distribution of isolated chromatin granules can be
followed. The granules first become aggregated into definite tracts,,
and these form the primordia of the chromosomes themselves. The
actual stages passed through are obscure, and even allied species
exhibit considerable differences amongst themselves. Thus in the
Amoeba, amitosis seems regularly to occur in Amoeba brevipes and
A. polypodia, and also in A. crystalligera ; but in A. hyalina, accord-
ing to Dangeard, the chromatin separates from a central body and
is differentiated to form chromosomes, whilst the remainder of the

body gives rise to a rudi-
mentary spindle which is
entirely intra-nuclear. In
A. binucleata the two nuclei
divide simultaneously in a
mitotic manner, and the
same is true of the colonies
of the amoeba-like myxo-
mycetes. When a plas-
modium is about to form
spores, it may be found
with nuclei showing typical

Flo 19 karyokinetic figures, all the

nuclei being in the same
phase.

A remarkable dimor-
phism occurs in the nuclei of Paramoeba eilhardi, in which Schaudinn
describes one of them as resembling a normal amoeban nucleus,

B

Amoeba binucleata. A, with resting nuclei. B,
the two nuclei in the aster stage of mitosis. (After
Dangeard.)

THE STRUCTURE OF CELLS

whilst the other is much poorer in chromatin. During mitosis the
two act as complements, the latter nucleus furnishing the spindle
apparatus, whilst the former supplies the chromatin. Much specu-
lation has been built on this case, which is assumed by some writers
to indicate that the centrosome or centrosphere is equivalent,
phylogenetically, to a nucleus. But it may be open to doubt
whether the facts in Paramoeba have really been correctly inter-

Fio. 20.

Acanthocystis andeata. A and B, forma-
tion of the centrosome from nuclear
constituents in swarm-spores. C, resting
cell. D, nuclear division preceding fission.
(After Schaudinn.)

preted, in the sense of regarding the spindle-forming structure as a
genuine nucleus.

Many cases are known in which bodies which represent centro-
somes originate from the nucleus, as appears certainly to be the
case in Actinosphaerium, and especially in Acanthocystis, as described
by Schaudinn. In the latter animal the ordinary nuclear divisions
are associated with the fission of a corpuscle or centrosome occupy-
ing a central position in the cell, the nucleus lying close to its side.

42 THE STRUCTURE OF CELLS

But in the numerous instances in which amitosis occurs (as in
budding), the " centrosome " does not divide, and the nucleus of
the freshly-budded cell possesses no such structure. Soon after the
complete formation of the bud, however, a dense spot is formed
within the nucleus, and is then extruded into the cytoplasm, where
it continues to function as a centrosphere. The evidence, as drawn
from a study of the lower organisms, seems to point strongly in
favour of a nuclear origin for the centrosome apparatus in many
cases, although the simplest examples cited on a previous page also
indicate that, in others, such a structure might be coeval with, if
indeed not actually antecedent to, the primary differentiation of a
true nucleus.

In a considerable number of cases it seems at least clear that
the body or the substance which stimulates and brings about the
division of a nucleus is derived from the nucleus itself, even though
it may migrate into the cytoplasm, where it may continue to exert,
under appropriate conditions, that influence on the nucleus which
culminates in division. Thus, in diatoms the centrosphere is
found in the cytoplasm, just as it exists in many metazoon cells.
The actual location of the centrosome does not necessarily, however,
settle the question as to its real origin, and it may indeed assume
an intra- or extra-nuclear position in closely allied forms ; as, for
example, in the two varieties of Ascaris megalocepJiala, being
situated within the nucleus in the variety univalens, and outside it
in the variety bivalens.

A remarkable side issue has been introduced into the contro-
versy as to the phylogenetic origin of the centrosome by a considera-
tion of the peculiar nuclear apparatus which is met with in most
ciliata and suctoria. These organisms, with a few possible exceptions,
possess a mega- and a micro-nucleus, the former presiding over the
somatic life and divisions of the animal, the latter only becoming
prominent during the phases of sexuality. Some writers have
sought to derive, phylogenetically, the centrosome from the micro-
nucleus, whilst they see in the meganucleus the representative of
the metazoon nucleus. But quite apart from the fact that, as
Schaudinn pointed out, centrosomes appear in the much simpler
heliozoa, the fact that the micronucleus alone divides mitotically,
whilst the meganucleus always does so by amitosis, seems a serious
difficulty in accepting such an interpretation. Moreover, the macro-
nucleus itself springs from the micronucleus after each sexual act,
and only persists till the close of the sexual cycle, at which period
it totally disintegrates, and thus suffers somatic extinction. It
would certainly appear that at any rate it is useless to look to such
a source for the origin of the centrosome, which really seems to
rest on no better basis than a purely fanciful comparison.

A consideration of the maturation processes which obtain in

THE STRUCTURE OF CELLS 43

the lower plants and in the protozoa when more fully understood
will certainly shed light on the obscure phenomena exhibited by
the higher forms, and may ultimately give the clue for correctly
appreciating the general significance of the processes involved. It
has already been remarked that the exact point in the life-history
at which these remarkable divisions periodically recur is not identical
for all organisms, whilst the universality of the process indicates
clearly its great and fundamental importance. It has been urged
by some that the chromosomes, which are by those writers postu-
lated as permanent structures, become distributed between the
daughter cells in such a manner that only half of the original
number persist in each sexual cell. And in this way room is made
for the new ones imported in either of the two conjugating gametes.
Others again, like Oscar Hertwig, regard the quantitative reducing
of the chromatin (as opposed to that of the chromosomes) as the fact
of prime significance. In many of the lower forms, and notably in
the coccidia, the evidence tells strongly for this view ; for in them
it is the definite fact that a large part of the mother nucleus is left
unused when the gametes or gametocytes are produced, and thus
there is a quantitative reduction of a very pronounced character.
Again, in the same organisms the multiple division of the nucleus,
taken together with the amitotic division of the nucleus of the
zygote at segmentation, seem to tell equally against a mechanical
necessity for similarity in the chromatic strands. It is not easy to
believe in the permanent existence of specific chromosomes under
such circumstances ; but, on the other hand, there is no doubt that
if the different chromatic granules do really represent slightly
different structural characters, a qualitative reduction much in
the sense assumed by him may actually take place. For there
can scarcely exist any doubt but that, as the result of these pro-
cesses, the surviving parts of the mother nucleus do not represent
(especially after a multiple division) exact images of the original
nucleus from which they have sprung. But it would also seem to
be clear that whilst both a quantitative and a qualitative reduction
have taken place, these can hardly be regarded as direct means of
ensuring that an unvarying proportion of the original chromatin
shall be distributed amongst the daughter nuclei. Whether the
constant proportions observed in the higher forms is to be explained
as the result of a more definite constancy in the chromosomes,
together with the continuous existence of these structures in the
hypothetically more specialised nuclei of the higher animals and
plants, is a matter upon which it is as yet impossible to make any
positive statement. It may, however, be confidently asserted, having
regard to the extraordinary diversity which prevails in the details
of nuclear transformations in these lower forms, many of which will
be found described in the present volume, that amongst them,

44 THE STRUCTURE OF CELLS

if anywhere, are to be sought the clues to the complex though
less variable processes which characterise the higher animals and
plants.

The phenomena of the sexual union of germ cells, and of their
contained nuclei, for the most part are, as yet, hardly susceptible of
detailed explanation, but there can be no doubt but that chemiotaxis
is the proximate factor chiefly concerned. This is beautifully shown
in the case of Halidrys, one of the Fucaceae, in which the large
eggs attract numbers of sperms which seek to penetrate the egg.
Immediately after an entrance has been effected by one of them, it
is seen that the egg changes in important respects. It shrinks,
and the supernumerary sperms instantly cease their endeavours to
enter its substance. On the contrary, they swim rapidly away,
and from the surface of the egg a substance is seen to be excreted
which probably exerts the repellent influence in question. Indeed,
so strong is its action that those sperms which have not quitted
the surface of the eggs are rapidly paralysed and killed.

The remarkable paths followed by the male nucleus in the egg
has been studied by many observers, and there can be but little
doubt that here also a specific attraction of some sort effects the
final union. As to the significance of the fusion, the evidence at
present available points in no certain direction, nor can any of the
hypotheses which have as yet been advanced to explain it be
regarded as affording satisfactory solutions of the problem. It has
been assumed that by its means a sort of rejuvenescence is effected.
But this idea, which is not very clear in itself, fails to take the
many subsidiary but still general recurring circumstances into con-
sideration. Moreover, it is difficult to see why a similar explana-
tion should not also cover those vegetative fusions common in
endosperm cells and in certain fungal hyphae, but these have never
been regarded as constituting sexual acts.

And indeed it would appear that the actual initiation of segment-
ation in an egg is not necessarily dependent on the fusion or even
the presence of two nuclei. Boveri's observations on the fertilisa-
tion of enucleated fragments t)f eggs with sperms, and still more
those of Loeb, who succeeded in causing the eggs of sea-urchins to
segment parthenogenetically by treating them with magnesium
chloride, indicate that the matter is of far greater complexity than
a study of the normal occurrences would indicate. Again, Nathan-
sohn caused parthenogenetic development of the oospheres of
Marsilea to take place by keeping them at a sufficiently high
temperature.

This last observation seems to be one of greater importance, for
it suggests that a slight modification of the metabolic processes,
in this case effected by the abnormal temperature, may suffice to
set the machinery of segmentation in motion; that is, the actual

THE STRUCTURE OF CELLS 45

mechanism is already present in the egg, and only an appropriate
stimulus (not the importation of a missing half of the machinery)
is required to set it in motion. Long ago Boveri suggested that
the centrosome rather than the nucleus was the important body
the introduction of which starts the process of segmentation, and
it may well be that his suggestion, in a modified form perhaps,
and without postulating an organisation of the specific excitatory
substance in so definite a form as a centrosome, may contain a con-
siderable element of truth.

Amongst the lower organisms, as Klebs and others have shown,
the conditions favourable to the formation of sexual cells can be
largely referred to nutritive sources, and this is only another way
of saying that a definite stimulus — ultimately working on the living
substance of the organism itself — is responsible for the sexual reaction.

But such a view of the matter leaves untouched the question
of the secondary utility of sexuality as a means of ensuring variation.
Indeed, this latter is perhaps best kept distinct from the primary
causes and conditions which first made sex not only a possible
but an inevitable incident in the life cycle of the greater part of
the higher organisms.

Less obscure than its relations to the phenomenon of sex are
those which exist between the nucleus and the life of the cell.

Gruber, Nussbaum, Verworn, and others have shown that
in protoplasm which has been deprived of its nucleus the
vital functions speedily become more or less deranged, and finally
cease altogether. Enucleated fragments of a cell or organism
fail to regenerate lost parts, and the apparent exceptions that have
been met with constantly turned out, on further investigation, to
be contaminated with nuclear influence. Enucleated fragments of
an amoeba are unable to excrete the substance which normally
enables these animals to cling to the substratum, and in other
organisms, although food may be ingested, the protoplasm seems
unable to digest and assimilate it. In plants Gerassimoff has
shown that cells containing chlorophyll but destitute of a nucleus
are usually unable to form starch, and are incapable of excreting a
limiting membrane over their free surfaces.

On the other hand, allusion has already been made to the
transformations the nucleus may undergo in connection with the
secretory activity of glandular and other cells, and in this connec-
tion, no less than in that of regeneration, the nucleus may be
affirmed to preside over the metabolism of the protoplasm.

The peculiar processes which are extruded by the nuclei of the
nutritive cells surrounding the ovum (Ophryotrocha), and the
curious simulation of the initial phases of mitosis met with in
secretory cells, can hardly be dissociated from the special functions
discharged by their nuclei.

46 THE STRUCTURE OF CELLS

Again, that frequent migration of the nucleus to the seat of
special metabolic activity, so often illustrated in plants, affords
additional indication of an exercise of the same influence. The
developing of a lateral outgrowth on a plant hair, one-sided
thickening of the cell-wall, the softening of the latter previous to
its perforation — all these are commonly preceded by the arrival
of the nucleus at the part of the cell about to be affected.

And the very facts of mitosis itself, with the profound chemical
and physical changes which accompany it, suffice of themselves to
prove that the nucleus contains substances which are capable of
undergoing rapid and striking changes. And indeed it is perhaps
not improbable that it is in that very lability characteristic of the
constitution of the complex substances which together make up a
nucleus that the supreme importance of this body to the cytoplasm,
and through the latter to the organism as a whole, is to be
attributed.

THE PKOTOZOA (continued)

SECTION I. — THE FORAMINIFERA 1

CLASS FOKAMINIFEKA

Order 1. Gromiidea.

„ 2. Astrorhizidea.

„ 3. Lituolidea.

„ 4. Miliolidea.

„ 5. Textularidea.

„ 6. Chilostomellidea.

„ 7. Lagenidea.

„ 8. Globigerinidea.

„ 9. Rotalidea.

„ 10. Nummulitidea.

THE Foraminifera received their name before their nature was
understood. The early anatomists, guided by the likeness of many
of their tests to the nautiloid shells of the Cephalopod Mollusca,
assigned them to this group, and many Foraminifera were included
by Linnaeus and later writers in the genus Nautilus. D'Orbigny,
in 1826, divided the "Cephalopoda," having chambered shells, into
Siphoniferes, with a more or less tubular siphon traversing the
series of chambers ; and Foraminiferes, in which the chambers are
in communication by foramina. The simple character of the organ-
isms which secreted these shells was first recognised (1835) by
Dujardin, who placed them with Amoeba, and allied fresh -water
forms in the group Rhizopoda.

The limits of the group Foraminifera, as here understood, are
identical with those of the Reticularia, as defined by Carpenter in
his Introduction to the Study of the Foraminifera (8). It includes
those Protozoa the protoplasm of which secretes a test (or shell), and is
protruded in fine thread-like pscudopodia, which branch freely and
anastomose with one another, and present no obvious differentiation into
ectoplasm and endoplasm.

The great majority of the members of the group form a well-
defined assemblage of organisms, clearly allied to one another, and
distinct from any other division of the Protozoa ; but we cannot
at present draw with any certainty the limits between the simpler
forms here included and some other simple members of the Protozoa.

1 By J. J. Lister, M.A., F.R.S., Fellow of St. John's College, Cambridge.

47

48 THE FORAMINIFERA

Each of the characters by which the group is defined loses in
distinctness when followed into this borderland region. The shell,
which attains great complexity in the higher forms, is membranous
in many of the lower, and in Lieberkiihnia, Diplophrys, and Myxotheca
(Fig. 2) can hardly be said to exist. In Hyalopus the pseudopodia,
though branching and pointed, do not anastomose with one another
(Fig. 15), and in several of the fresh- water Gromiidae few anasto-
moses are found. The filiform nature which distinguishes the
pseudopodia of the Foraminifera from the blunt-ended pseudopodia
of the Lobosa is a better defining character; but in view of the
close parallel which, as will be explained below, the life -history
of Trichosphaerium, a member of the Lobosa, appears to present with
that of many Foraminifera, its importance in a natural classification
may be doubted.

A few of the simpler forms live in moor pools and other fresh
waters, but the great majority are marine. Most of these are
littoral in habitat ; many extend their range to the floors of the
deep oceans ; while a small group, few in the number of species,
but very abundant in individuals, lead a pelagic existence.

The Protoplasm presents a uniform character without any obvious
separation into an outer and inner layer of different refracting power.
It is finely granular throughout, and coarse granules are usually
present in the protoplasm contained within the test.

The pseudopodia in some of the lower forms are long and root-
like, and extend to great distances, giving off branches in their course,
and to such forms Dujardin's name Rhizopoda is especially appro-
priate ; but most members of the group are characterised by pseudo-
podia of a different nature (Fig. 1). They are for the most part
very slender, and spread from the neighbourhood of the aperture
or apertures of the shell in fan-like or sheaf-like groups. The outer
surface of the shell is invested by a layer of protoplasm, and from
this also groups of pseudopodia originate.

The pseudopodia frequently branch and anastomose in their
course, and between the points of union of the reticulum which
they form, they generally run straight, owing in part to the tension
which they mutually exert on one another. Some of the radiating
strands form broad bands, branching peripherally, but the majority
are exceedingly slender, and the ultimate branches are of extreme
tenuity. At the points of union broad expansions of protoplasm
are often formed. The network of pseudopodia is in part projected
free in the water, in part applied to surrounding objects, and
serves at once for the prehension of food, as a peripheral sensory
apparatus, and as a means of attachment and of locomotion.

When a strand of the reticulum is attentively examined, the
granules contained in the protoplasm are seen to hurry along its

Fio. 1.

Gromia oviformis, Duj. 1, contour of protoplasm contained withiu the test ; 2, protoplasm
reflected over the test 3, extended pseudopodia. (From Shipley and MacBride, after Max
Hchultze.)

50 THE FORAMINIFERA

surface, as though borne by a stream, and two streams of granules
flowing in opposite directions, centrifugal and centripetal, are to be
seen on opposite sides of the same filament. Sometimes a mass of
protoplasm forms a swelling on the surface, and is carried along for
some distance before it thins out and merges in the substance of the
filament.

The tip of a pseudopodium may be seen to be alternately ex-
tended and retracted according as the centrifugal or centripetal
stream gains the ascendency. A mass more solid than the rest of
the protoplasm may be seen to be carried to the tip, turn and pass
back for some distance with the return current, then to be caught
in the centrifugal stream, and again carried to the tip. One is
reminded of a cork at the summit of a jet of water, under the
contending forces of the upward flow of the jet and of gravity.
But the cause of the streaming movement in the pseudopodia of
the Foraminifera, like the ultimate cause of movement in all
contractile tissues, is still beyond the limits of our knowledge.

The minute structure of the protoplasm has been carefully ex-
amined by Biitschli, who finds in the coarser pseudopodia, and in
the membranous expansions between them, the alveolar structure
which is present in so many protoplasmic structures. In the fine
pseudopodia, however, this is absent, and they appear under the
highest powers as homogeneous threads of extreme tenuity, with the
small granules scattered along their surface. From the peculiar way
in which, in the living pseudopodium, the granules course along the
threads, sometimes leaving them for a moment to pass apparently
through the open water, Biitschli is inclined to the view, suggested by
Max Schultze, that an invisible hyaline layer may invest the visible
threads of the Foraminifera in the same manner as the more visible
hyaline ectosarc invests the axial endosarc of the pseudopodia of the
Heliozoa.

In addition to this intrinsic streaming movement there is a
movement of the reticulum as a whole. New pseudopodia shoot
out from the central mass, others are shortened and retracted, and
the whole system is in a condition of tension and constant move-
ment, as becomes evident at once when an attempt is made to draw
any part by camera lucida. When a strand of the reticulum gives
way a momentary collapse of the neighbouring strands is seen,
followed by the rapid lengthening of some strands and shortening
of others, resulting in renewal of the tension.

The food of Foraminifera consists largely of diatoms and algae,
either alive or in a state of decay. In some cases, however, it is of
animal nature, for Rhumbler finds that the Globigerinae capture and
digest the Copepods which abound at the sea surface, and that the
pelagic Pulvinulinae contain the skeletons of Radiolaria as well as
of diatoms, which have been taken as food (38, pp. 1 and 2).

THE FORAMINIFERA 51

Schaudinn also has witnessed the capture and digestion of a
Copepod by Myxotheca (41, p. 25), and finds that Patellina and
Discorbina feed on Copepod nauplii and Infusoria as well as on
Diatoms (45, p. 182). The pseudopodia of Gromia and Poly-
stomella have been seen to exercise a paralysing effect on Infusoria
which come in contact with them (M. Schultze).

The pseudopodia are exceedingly viscid. When an object which
serves as food is entangled it becomes surrounded by protoplasm,
and if it is large the strands of the reticulum between it and the
shell become thicker and more numerous, and the object is drawn
inwards. Whether digestion may occur in the extended protoplasm
or only after the food enters the shell is uncertain.

Myxotlieca arenilega, Schaudinn. N, nucleus; t, the gelatinous test with embedded sand grains.
(After Schaudinn, 41.)

Contractile vacuoles occur in some of the fresh -water forms
(Eugli/pha, Trinema, Cyphoderia, Microgromia, and Platoum), but they
have not been seen in any of the marine genera.

The granular bodies which are scattered through the protoplasm
are of different kinds. Some are coloured, and confer a red,
yellow, or brown colour on the protoplasm when seen in bulk.
These are allied in composition to the colouring matter of diatoms
(diatomin), and are probably derived directly from the food. Some
are fatty ; others, apparently proteid in nature, are stained by
picrocarmine, and are probably formed in the ascending metabolism
of the food. In OrUtolites comphnata starch grains are abundant,
but their formation is probably dependent on the presence of the
parasitic algae (zooxanthellae) which abound in the protoplasm in
this species. These algae also live in the pelagic Globigerinae.

52 THE FORAMIN1FERA

The nuclear characters and modes of reproduction of the Foramini-
fera are considered below.

The Structure of the Test. — The test is found in its most rudiment-
ary condition in Myxotheca, where it consists of a gelatinous layer,
which may form the whole covering or may contain grains of sand.
The shape follows the changing contour of the protoplasm, the
pseudopodia break through at any point, and no definite and
permanent orifice is formed. In Hyalopus (Fig. 15) the test is
more resistent, and may have an oval form and a definite orifice ;
but here again the shape varies with that of the contained proto-
plasm, becoming arborescent when growing among the crowded
stems of algae, and the number of orifices may be indefinitely in-
creased (Schaudinn, 43). In most of the Gromiidea the test is
chitinous and flexible ; but it has a definite shape, and one or two
permanent orifices.

Another type of test is found in some Gromiidea, and in all the
Astrorhizidea and Lituolidea. The tests are here formed of foreign
particles, such as fragments of sand, sponge-spicules, the shells of
other Foraminifera, etc., fastened together by a cement, which may
be firm or flexible, and consist of chitin or calcium carbonate or
ferric oxide. In the Astrorhizidae the walls are thick and soft, con-
sisting of mud, or of only slightly cemented sand (Fig. 17, a), while
in other cases, as in Saccammina (Fig. 17, &), the particles are
united into a rigid structure.

In some species of Textularia, Quinqueloculina, and other genera,
though the tests are chiefly calcareous, a large proportion of foreign
arenaceous material is contained in them.

A very remarkable feature of the tests of arenaceous Foramini-
fera is the evidence they appear to offer of a selective power exercised
by certain species, in collecting materials. In some cases, no
doubt, the nature of the test depends on the constituents of
the sea bottom in which the animal lives, but in others certain
elements alone are selected. Thus in the same dredgings may be
found the tests of Pilulina and Saccammina, the former composed
of a close felt of siliceous sponge-spicules, laid together to form a
wall of uniform thickness ; the latter of coarse grains of sand united
by cement (Fig. 17, b and c). In both the test consists of a single
spherical chamber, and the size attained is about the same in both.
The cylindrical tests of Bathysiphon filiformis, Sars, are composed of
a felt of sponge-spicules, covered externally by a layer of fine sand.
The same sample of Pteropod ooze supplies representatives of
species of the family Lituolidae, characterised by the coarseness of
the sand grains of which the tests are composed ; and of Trochammi-
nina distinguished by fine-grained tests.

The type of test found in Euglypha (Fig. 3) and its allies is very
exceptional. It is formed of rounded or hexagonal plates, of siliceous

THE FORAM1NIFERA

53

or, in some cases, chitinous nature, which are secreted in the sub-
stance of the protoplasm in the neighbourhood of the nucleus. Passing
to the surface, they are there built together into a regular test. With the
exception of some forms
of BttocutinO) which have
been found when living
at great depths with a
siliceous shell instead of
the normal calcareous one,
this is almost the only
instance of the secretion
by the Foraminifera of a
siliceous skeleton — a fact
which is all the more
remarkable in considera-
tion of the prevalence of
siliceous skeletons among
the Radiolaria and He- c
liozoa.

In most of the other
orders of Foramini-
fera, though a chitinous FIG. 3.

element is present in Euglypha ulreolata. Two stages in the process of division.

tVm eL-olofr> if- i ft 1 ^n one *ne nuc'eus is about to divide, and the plates which

SKCietOn, 1C K Only Wjn form the new shell are seen in the protoplasm ; in the

tVip hfl«ic in wViinVi r>ar other the division is nearly complete. c.r, contractile

Car vacuole. (After Schewiakoff, 48.)

Donate of lime, together

with a small proportion of carbonate of magnesium and traces of

other salts, are deposited.1

1 The following analyses are given by Brady (3, pp. xvii. and xxi.) of the tests of
two species — one porcellanous, belonging to the Miliolidea ; the other perforate (see
footnote, p. 54), a member of the Nummulitidea : —

Orbitolites complanata, var. laciniato.
Silica ......

Carbonate of lime ....

Carbonate of magnesia ....

Alumina with phosphate of lime and magnesia
Alumina and ferric oxide

Amphistegina lessonii.
Silica .....
Carbonate of lime with a little organic matter
Carbonate of magnesia

Alumina with phosphates of lime and magnesia
Ferric oxide

0-14

8874

9-55

. 1 occasional
. j traces

98-43

0-30
92-85
4-90
1-95
trace

100-00

Sollas has examined the specific gravity of the shells of perforate and imperforate
species of Foramiuifera (66, p. 374), and finds that in perforate forms it varies from 2'626
to 2'674. In examples of MUiola, Peneroplis, and Orbiculina it varies from 27 to

54 THE FORAMINIFERA

In these the tests are rigid structures, and communicate with
the exterior either by one or more large apertures exclusively, as in
the majority of the Miliolidea, or by a multitude of small pores in
their walls in addition to the large apertures.1 In some genera
of the Miliolidea the shells have a polished white appearance re-
sembling porcelain when seen by reflected light, and a yellowish
brown horn colour when seen by transmitted light ; in the per-
forate forms the tests are more transparent, and are in many cases
as clear as glass. On this account the forms with perforate cal-
careous tests are often known as the vitreous or hyaline Foraminifera.

In the perforate forms the pores passing out from the chambers
have, on the whole, a direction perpendicular to the walls, and
transmit pseudopodia. In some cases the pores are large and com-
paratively few, in others they are fine and very numerous.

The Growth of the Test. — In forms such as Myxotheca and Gromia
the growth of the protoplasmic body is accommodated by the simple
expansion of the soft and membranous test. Among the arenaceous
forms, the feebly cemented, star-shaped tests of Astrorhiza (Fig. 17,
a) increase in size in part by the extension of the test along the
protoplasmic trunks forming the rays of the star, but in part,
doubtless, by the expansion of the central body. In the case of
Saccammina (Fig. 1 7, b), however, and other forms with rigid single-

2722. The specific gravity of calcite is 2'72, and that of aragonite 2'97. He con-
cluded that the calcareous constituent of the perforate tests is calcite, and that of the
imperforate tests either aragonite or calcite together with some other and heavier
substance. Cornish and Kendall (12) had previously indicated the conclusion, though
without positively stating it, that the porcellanous Foraminifera were composed of
aragonite — on the grounds of their opacity, and their appearance in or absence from
beds coincidently with Lamellibranch and other fossils which are composed of ara-
gonite. Chapman (11, p. 39) also has recently stated that the tests of the Miliolidea
are of aragonite, or rather (following Miss Kelly, Mineralogical Mag. vol. xii. (1900),
p. 363) conchite.

I am inclined to doubt this conclusion. It appears that the presence of the mag-
nesium carbonate (specific gravity 3'056), which Brady's analysis shows is a larger
constituent of the imperforate tests than of the perforate, may cause the higher
specific gravity found in the former by Sollas. Moreover, Meigen (22) has recently
described a chemical colour test by which calcite may be distinguished from ara-
gonite, or from the constituent which Miss Kelly has named conchite. Tried by
this test, I find that Miliolina and Orbiculina and Orbitolites do not give the colour
reaction characteristic of aragonite, but agree with structures composed of calcite.
I am indebted to Mr. A. Hutchinson for calling my attention to Meigen's paper.

1 In the systems of classification prepared by Reuss (1861) and by Carpenter
and his colleagues (1862) the Foraminifera were divided into the two groups,
the Imperforata and the Perforata. In the latter classification the group Imperfor-
ata includes the Gromida, Litnolida, and Miliolida; the Perforata the Lagenida,
Globigerinida, and Numrmditida (i.e. families 5-10 of Brady's classification, which is
followed in this article). The progress of deep-sea investigation since this date has
revealed the existence of the Astrorhizidea, some of which have perforate and others
imperforate tests. Moreover, even in the Miliolidea the first formed chambers may
be perforate in the genus Peneroplis (Rhumbler), and in Orbiculina and Orbitolites,
as shown in this article. It thus becomes evident that the presence or absence of
perforations in the shell, though perfectly characteristic of many of the orders, cannot
be taken as the basis for the subdivision of the whole group.

THE FORAMINIFERA 55

chambered tests, the way in which the growth of the protoplasm is
accommodated is less obvious.

It is probable, however, that here also the shell, though at any
particular moment rigid, is slowly moulded and expanded under the
influence of the protoplasm. The small tests hitherto classified as
Psammosphaera fusca, but regarded by Rhumbler (33) as the young
of Saccammina sphaerica, with which he finds them to be connected
by all intermediate forms, are built up of fragments of sand placed
together irregularly, so that the contour of the young test is rough
and uneven. In the full-grown Saccammina test the fragments are
placed, as in a well-constructed stone wall, to form an even contour.
If, as these facts imply, a change in position of the constituents
has occurred during growth, there is no difficulty in accepting the
conclusion at which Rhumbler arrives, that it has also undergone
expansion as a whole. The alternate hypothesis, that in the course
of growth to its full size (3*5 mm.) the protoplasm periodically
discards its old shell and builds a new one, appears improbable, and
the student of the growth of bone will find no a priori difficulty in
admitting that a rigid structure may be the seat of profound inter-
stitial changes of substance.

The growth of the tests of the cylindrical forms of the Astro-
i-hizidea is effected by extension in a linear direction, fresh arenaceous
material being incorporated at their ends. They form simple or
branched (many Hi/per a mminae, fihizammina), but usually un-
segmented tubes. In Hyperammina subnodosa (Fig. 1 7, d] the tubes
are constricted at irregular intervals, and thus present a transitional
condition of structure to the definitely segmented, chambered shells
of the great majority of Foraminifera. In the latter, while the
growth of the protoplasm as the result of the assimilation of food is
continuous, the growth of the shell is not continuous but periodic.
When a new chamber is to be formed, a mass of protoplasm is
protruded from the mouth of the shell, and at the surface of this
the new wall is formed, by secretion in the case of calcareous
shells, by cementing together of foreign elements in the arenaceous
forms. In some genera the secretion of shell substance takes place
only on the free surface of the protoplasm, but in others it occurs also
where the protoplasm rests against the previously formed test. In
such cases the septa dividing the chambers are double, and the new
chamber is complete on all sides with the exception of the aperture
or apertures left for communication with the exterior, or with its
successor, Avhen a new chamber shall be added. In either case the
result of this periodic shell formation is the building up of a
segmented test, the segments of which, the chambers, are sharply
marked off from one another.

Max Schultze found that in the formation of a new chamber by
Polystomella, the deposit of calcareous salts began before the chamber had

56 THE FORAMINIFERA

assumed its final form. The small pocket-like " retral processes," which
are characteristic of this genus (see Fig. 7), were not formed until some
time after a continuous wall had been secreted, so that a partial absorption
and re-deposition of the lime salts must here occur (64, p. 30).

Structure and Mode of Growth of the Shell Wall. — After their first
formation by secretion at the surface of a mass of protoplasm, the
walls increase in thickness by the addition of shell material to the
outer surface. The anterior wall of each chamber is soon covered
by the addition of a new chamber in front of it, and it then forms
the whole, or half (as the septa in the species concerned may be
single or double), of the septum dividing the chambers from one
another. On the septa of the perforate forms the pores may be
limited to the peripheral parts or absent altogether.

The thickness attained by the septa is not great, but the part of
the wall turned to the outer world continues to grow, and may
attain considerable thickness.

The thickening results from the addition of successive layers of
material on the outer surface, and thus a laminated structure is
produced ; but though laminated tangentially, the shell is built up,
where it is perforated, of hexagonal prisms disposed radially to the
surface, and each traversed by a pore transmitting a pseudopodium.

It appears that this result may be explained as follows. The shell
material is deposited by the protoplasm traversing each of the pores which
perforate the wall, on the area about its orifice. It would appear that at
the limits between the areas influenced by neighbouring pseudopodia there
is some slight difference in the character of the material secreted, and the
result is that the deposit is not quite uniform, but marked out into small
hexagonal areas, with a pore at the centre of each. If this is the case,
the prismatic structure results from the observance of the same limits in
successive layers throughout the thickness of the shell.

In the more complicated perforate Foraminifera a system of
sinuses or canals is present, the main channels of which run in the
substance of the shell, and are distinct from the cavities of the
chambers, though communicating freely with them by branches.
This is known as the canal system. It is, of course, wholly distinct
from the radial pores leading direct from the chambers to the
exterior. The details of its distribution in Polystomella are given
below (cp. Fig. 9). It will be seen that in this form two main
"spiral canals" run on either side of the test, parallel with the
series of chambers, and give off branches, some of which run in
the thickness of the septa between the chambers, while others pass
direct to the exterior in the axial regions of the test. About the
ultimate branches of the canal system a deposit of shell substance
is laid down, which may be called the canalicular skeleton. In the
test of Polystomella this skeleton is mainly limited to the axial regions,

THE FORAM1NIFERA

57

but in other genera it forms extensive deposits in the interior of
the septa, and on the surface of the test. It attains a great
development in Calcarina.1

Where the canalicular skeleton comes in contact with that of
the chamber walls, the two merge insensibly into one another ; the
only distinction between them is that one is penetrated by the
branches of the canal system, the other by radiating pores leading
direct from the chambers of the test.

Some confusion has arisen in the use of the terms intermediate or
supplemental skeleton, and proper chamber wall. In the Introduction to
the Study oftlie Foraminifera (p. 50) Carpenter says that the "intermediate
or supplemental skeleton " is " formed by secondary or exogenous deposit " ;
and further, that wherever developed to any considerable extent, " it is
traversed by the canal system." The statement that the supplemental
skeleton is formed by a secondary or exogenous deposit appears unfortunate,
for the walls of the chambers of all the perforate calcareous forms are at
first exceedingly thin, and they increase in thickness by the deposition of
shell substance on their outer surface, so that the greater part of the
shell in all may be said to be secondary and exogenous. The part of the
shell first formed is in most, if not all, cases quite indistinguishable from
that which is added later.

The second character oftlie supplemental skeleton given by Carpenter,
that it is traversed by the canal system, does, however, touch on a real
distinction.

Biitscbli (6, pp. 26-27) calls attention to the fact that a difference
between a primary shell layer (Carpenter's " proper wall " ) and a
secondary mass is often indistinguish-
able ; but he proposes to use the
latter term for the outer layer of
the shell, whether unperforated,
perforated by radial pores, or by
branches of the canal system.

It appears to be more advan-
tageous to distingiiish the skeleton
developed in relation with the canal
system from that of the chamber
wall, and as confusion is attached
to the name supplemental skeleton,
the term canalicular skeleton is
used in this article for the former.

Repair. — The power of re-
pairing injuries is very great,
and indeed a fragment may,
in some cases, give rise to a
new individual. This is well
seen in the specimen of OrUtolites tenuissima shown in Fig. 4,

1 Cp. Carpenter, 8, p. 216.

Fio. 4.

Specimen of Orbitolites tenitisslma in which
a fragment of a test has given rise to a new
disc. (From Carpenter, 9, Plate I. Fig. 7.)

58 THE FORAMINIFERA

in which it is interesting to note that the centre of symmetry of
the growth which occurred after the injury is entirely different
from the original one.

Verworn (67, p. 455) finds that when a specimen of Polystomella
crispa (his observations were doubtless made on megalospheric
forms, see below) is broken into fragments, several of the larger
pieces remain alive and extend pseudopodia, but new shell is
secreted over the broken surfaces by only one, and this is found on
examination to be the fragment in which the nucleus is contained.

The Form of the Test. — The principal forms of test met with
among the Foraminifera will be considered later. We shall see
that in some genera a particular mode of growth, in relation to
some simple symmetrical plan, whether rectilinear, piano -spiral,
helicoid, or annular, is observed with perfect regularity, while in
others a symmetrical plan is only loosely followed. Many species
are adherent to other objects, and in them the chambers may be
" heaped " together irregularly, forming what are known as the
" acervuline " tests.1 Some of the adherent forms take on an
arborescent shape.

Multiform Tests. — A remarkable phenomenon is presented by
many genera, and that is that the plan on which the chambers are
arranged in the growth of the test changes in the course of growth.
In such tests the chambers which succeed the central one are
arranged on a particular plan, whether piano-spiral, helicoid, or
some other, and after growth has progressed on this plan for some
time a change occurs, and a new plan of growth is with greater
or less abruptness adopted (Figs. 24, 39, 40, 44, etc.). In some
cases the plan of growth may be changed more than once before
the test is completed. Thus two or more types of arrangement of
the chambers are, in these genera, presented by the same test at
different stages of its growth. The genus Spiropleda is an example
in which the chambers are at first uniserial and arranged in a
piano-spiral, and later biserial and in a rectilinear series (Fig. 44,
A and B). To tests exhibiting such different modes of growth the
terms dimorphic, trimorphic, and polymorphic (according to the
number of forms of growth present) were originally applied, and
the phenomenon of their occurrence was spoken of as dimorphism,
trimorphism, or polymorphism. But it has since been discovered
that two kinds of individuals occur in the life-cycle of many For-
aminifera, and for this, which is, of course, an entirely distinct
phenomenon, the term dimorphism has, in accordance with
customary biological usage, been adopted. It has thus become
necessary to find other terms to characterise tests displaying
two or more modes of growth, and the adjectives Informed
and informed may, as proposed by Rhumbler (36, p. 63), be con-

1 A cerv us, a heap.

THE FORAMINIFERA

59

veniently used for this purpose. In what follows I have used the
term multiform to cover any departure from the uniform condition
of growth.

It is shown below that while in some genera both forms of
individual which are found in one species are alike bi- or tri-formed,

FIG. 5.

Block of Eocene limestone, showing the two forms of a species of Nummulites, constituting
"a pair" ; the larger named N. biarritzensis, the smaller N. guet.tfi.nli, d'Arch. Specimen from
Deir en Xakhl, Egypt, in the Brady Collection, Cambridge.

in others the phenomenon is exhibited by only one form (the
microspheric), or exhibited by it to a greater degree.

The Phenomenon of Dimorphism.

This phenomenon was first recognised in the fossil nummu-
lites which abound in the marine deposits of the Eocene period,
and are represented by a single species living at the present day.

60 THE FOR AMI N I PER A

They are often so abundant that, as in the rock of which some of
the Egyptian pyramids are built, their coin-like shells, whole or in
fragments, constitute the main part of the deposit (Fig. 5). The
shells are, in reality, not flat but biconvex discs, and the chambers,
arranged in a spiral, are so disposed that the greater part of the
cavity of each lies in the median plane, while the shell on either
side of this plane is comparatively solid. They thus readily
break, as the result of weathering or by artificial means, into
plano-convex halves, which display a section of all the chambers
from the centre to the periphery on their broken faces.

It has long been recognised that while the great majority of
the specimens of nummulites occurring in a deposit attain a
certain, moderate size, a few are found scattered through it, whose
diameter far exceeds that of the others. On examining median
sections of the smaller specimens it is usually found that the
spiral series of chambers starts from a large and nearly spherical
chamber readily visible to the naked eye, and occupying the
centre of the shell, while in the larger specimens the spiral series
is continued to the centre, where, in carefully prepared sections,
it may be seen to take its origin in a spherical chamber of micro-
scopic size (Fig. 6).

Although the two forms were thus found to be associated in
the same beds, and to agree with one another closely except in
the size to which they grow and the characters of the central
chambers, they were given separate specific names, and attention
was called to the puzzling occurrence of these associated pairs of
species, a large and a small one, in various deposits.

Thus the names Nummulites laevigata, Lam., and N. lamarcki,
d'Arch., have been given to two associated forms occurring in beds
of the Middle Eocene formation. The former attains a diameter
of 20 mm., while the latter does not exceed 3 or 4 mm. Small
examples of N. laevigata are not to be distinguished by external
characters from the associated form, but on splitting them open,
the difference in their central chambers is at once apparent
(Fig. 6). Sixteen pairs of similarly associated " species " belong-
ing to the genera Nummulites and Assilina have been enumerated.

The possibility that the two associated forms might belong to
the same species was, however, entertained by several observers,
and the acceptance of this view was accelerated by Munier-
Chalmas (26), who (in 1880) definitely formulated the conclusion
that the species of nummulites are dimorphic, each appearing
under two forms, a large one and a small one. He also expressed
the opinion that the phenomenon of dimorphism would be found
to be of general occurrence among the Foraminifera.

As already stated, the large forms with a small central chamber
are much less abundant than the others, and it so happened that

THE FORAM1NIFERA 61

young individuals of this form did not come under Munier-
Chalmas's observation. He was thus at first inclined to the view
that the individuals of the two sets, although in some way dis-
tinct in nature, began life under one form, namely, that with a
large central chamber. At a certain stage, it was supposed, the
growth of one set of individuals was arrested, while in the
members of the other set the walls of the large central chambers
were absorbed, and growth was continued not only by the addition
of chambers at the periphery in continuation of the series of those
already formed, but also in a centripetal spiral towards the centre

Nunimulites laevigata, Lain. A, Central portion of a section of the megalospheric form
("N. lamarcki," d'A.); 13, of the microspheric form. Both x 10. (After de la Harpe, 17.)

of the shell, filling the space originally occupied by the large
central chamber.

This idea of the relationship of the two forms was controverted
by de la Harpe, who pointed out, expressing his own views and
those of de Hantken, that young examples of the form with a
small central chamber are known to occur, and also that differ-
ences may be detected not only at the central parts of the shells
of the two forms of nummulites, but throughout the series of
chambers. Thus it is often found to be the case that in the forms
with a large central chamber (A, Fig. 6) the maximum size of the
chambers subsequently added is attained early in the series of
whorls, while in the others (B) the size of the chambers gradually
increases to the last whorl.

While the view that one form results from the modification of
the other was thus shown to be untenable, it was suggested that

62

THE FORAMINIFERA

they might with more reason be regarded as representing the two
sexes of a species. The authors did not, however, abandon the
old idea of the specific distinctness of the two forms.

Investigation of other genera of Foraminifera has shown that
the phenomenon of dimorphism is, as Munier-Chalmas expected,
widely found among them.

The relation between the two forms will be best elucidated by
examining the structure and life-history of a single species. For
this purpose we will select Polystomella crispa (L.), the life-history
of which is most completely known.

THE STRUCTURE OF POLYSTOMELLA CRISPA. — This is one of
the most abundant of the littoral Foraminifera. It lives in shore
pools and down to a depth of 355 fathoms, and ranges from Green-
land in the north and Kerguelen Island in the south to the equator.
It is very common on our own shores.

The test is biconvex and symmetrical about the median plane.
The chambers are arranged in a spiral series, and are equitant, i.e.
they bestride the chambers of the preceding convolution and over-
lap them at the sides, each being prolonged in what are known as
alar prolongations, which extend towards the spiral axis of the
test. Partly as the result of this overlapping, and partly because
the axial region is filled in with canalicular shell substance, only
the last convolution of chambers is visible externally.

On the terminal face of the last chamber, where this face

joins the wall of the
preceding convolution, a
V-shaped line of pores
(Fig. 7, a) is visible.
These represent the aper-
ture of the test, and are
the main channels of
communication between
the terminal chamber
and the exterior. At the
posterior margin (i.e. the
margin remote from the
terminal face) of each
chamber a number of
pocket-like prominences,
the retral processes (Figs.
7 and 8, r), project back-
wards, and are marked by
ridges on the external

surface. They end blindly, but are separated by pits, at the
bottoms of which are the openings

FIG. 7.

The test of Polystomella crispa (L.). x about 40.
a, the line of terminal apertures ; r, retral pro-
cesses ; between them are seen the pits by which
branches of the canal system communicate with the
exterior.

Of

system, which will be described later.

branches of the canal
The outer surface of

THE FORAMINIFERA 63

the shell is dotted over with minute tubercles (not visible in
Fig. 7).

A keel-like thickening runs round the margin of the test, and
in some specimens small spines, like the points of a spur, project
from it at the places where the septa join the keel. These
are more frequently present in the earlier than in the later
convolutions.

The pores traversing the walls of the chambers are in this
species exceedingly minute. They are hardly visible when the
test is seen from without, but they may be detected when a broken
piece of the wall is highly magnified and seen by transmitted light.

On examining the external characters of the tests of a number
of Polystomellas, they are found to form a uniform series, presenting
such gradations of size from small to large as may be seen, for
example, in a sample of the shells of any Mollusc which contains
young and old. If, however, a batch of living Polystomellas is
killed by some reagent which dissolves the shell but preserves the
protoplasm filling its chambers, the protoplasmic casts of the
shells no longer form a uniform series but fall into two sets (Fig. 8).

In the great majority of them the series of chambers, when
traced to the centre of the spiral, is seen to take its origin in a
large spherical chamber, having a diameter generally between 60
and 100 p.. In the others a small central chamber, with a dia-
meter of about 10 yu,,1 occupies the centre of the test, and the suc-
ceeding chambers of the series are at first correspondingly small,
so that for a given diameter of test these specimens have a greater
number of chambers than the others.

It is clear that though in Polystomella there is no marked differ-
ence in the size attained by the two forms, we have here the same
phenomenon of dimorphism which is exhibited in the nummulites.

The large central chamber is known as the megalosphere, the
small one as the microsphere, and the two sets of individuals of the
species are known as the megalospheric and microspheric respectively.
The numerical proportion of the two kinds of individuals probably
varies with the season, but the megalospheric form is here also
always the more abundant. In a large batch of several hundred
specimens the megalospheric forms were found to be thirty-four
times as numerous as the microspheric.

In the protoplasmic casts obtained in this manner the form

1 The diameter of the microsphere varies in the specimens of P. crispa which I
have seen from 6'5 to 13 jJ~ That of the megalosphere from 165 to 35 /tt. These
dimensions fall, however, a little short of the actual diameters of the chambers, owing
to the shrinkage of the protoplasm produced by the reagents. When comparing the
size of the microsphere in specimens preserved in this manner and in those examined
by sections of the test, it is well to bear this cause of difference in mind.

The number given as the diameter of a central chamber, in this article, is to be
understood as the mean between the long and short diameters as presented for
observation in the specimen.

64

THE FORAM1NIFERA

and disposition of the chambers are well displayed. In the

B

FIG. S.

Polystomella crispa. A, the megalospheric, B, the microspheric forms, decalcified, b, the
central chambers of the latter more highly magnified. The canal system is omitted in these
figures for the sake of clearness, r, retral processes ; st, communications between the chambers.

megalospheric form the retral processes characteristic of the genus
are present in the chamber following the megalosphere (Figs. 8, A,

THE FORAMINIFERA

m.c.

and 11, c). In the first convolution of chambers the alar prolonga-
tions are hardly formed, but as the series is followed on, they
project more and more at the sides, overlapping the chambers of
the preceding convolutions ; and as they increase the number
of apertures between successive chambers, single in the earlier
chambers, also increases (Fig.
8, A, Fig. 9, st), so that in
the terminal chamber there
is, as we have seen, a V-
shaped row of pores leading
to the exterior.

In the microspheric form
the arrangement is similar in
the later chambers, but in this
form the retral* processes are
absent from the chambers of
the earlier convolutions (Fig.
8,6).

The main trunks of the
Canal System lie in the um-
bilical region.1

They consist of a spiral
canal, on either side of the
test, running parallel with
and just internal to the ^-/^ "•''•:••• '^'••'•"•''./f^T^' r.fli'.

, A . /• ,1 i "*• VV3K1. .•••••:-. •-,'. ••.//• A»y I

lateral margins of the cham-
bers— whether these are pro-
duced into alar prominences
or not (sp.c, Figs. 9 and
11, c). Opposite the inter-
vals between the chambers
meridional canals (m.c) are
given off, and run in the
thickness of the septa, at
some little distance from

Fio. 0.

Diagram of a section through a megalospheric
example of Polystomella crispa. It is represented as
passing through the megalosphere but between the
other chambers, in order to show the disposition
of the canal system. M, the megalosphere ; m.c,
meridionial canal ; r.pr, retral processes ; ip.c, spiral
their OUter margins, tO meet canals ; st, protoplasm traversing the apertures be-
, . i j. tween the chambers. The dotted portion indicates

One another in the median the protoplasm filling the chambers, but the canal
nlanp "Prnm thpsp nnmhprc; s>'stem is represented as empty. The numerous
pldlie. rrom tnese numoers minute pores leading direct from the chambers to
Of short Canals pass OUtwards, the exterior are omitted, and the shell substance is

' left blank.

and, in the case of the outer

convolution of chambers, open to the exterior, into the pits

1 The canal system is said by Carpenter to be imperfectly developed in Polystomella
crispa (8, p. 282), and Mobius (25, p. 103) places P. craticulata, Fichte and Moll, in
a new genus Helicoza, on the ground that it possesses a branched canal system, absent
in Polystomella. In decalcified specimens of P. crispa, however, whose protoplasm
has been coloured dark by osmic acid, it is easy to convince oneself of the existence
of the system.

66 THE FORAMINIFERA

between the retral processes, before mentioned as visible on the
surface of the test (Fig. 7). The short canals springing from the
meridional canals of the inner convolutions open into the chambers
of the convolution next external. The canal system is thus in
communication with the chambers. In addition to the meridional
canals, other branches spring from the spiral canals and pass to
the surface in the umbilical region, traversing the thick mass
of canalicular skeleton there deposited.

The course of the spiral canals is in some cases irregular, and
they often break up into a network of sinuses. In the small
specimen shown in Fig. 11, c, the spiral canal of one side is seen
close to its origin, and a meridional canal is shown, between the
second and third chambers ; but I have been unable to trace the
points of origin of the spiral canals.

On treating a batch of decalcified specimens with a stain such
as picrocarmine, the nuclei appear, and again the two sets of
individuals come into marked contrast. The megalospheric form
possesses a single large nucleus, while the microspheric form
possesses a number of small nuclei, distributed through its
chambers (Fig. 8).

In Polystomella crispa, then, the megalospheric individuals
are numerous, they have a large central chamber and a single
large nucleus ; while the microspheric individuals are com-
paratively scarce, they have a small central chamber, and many
nuclei.

The existence of the phenomenon of dimorphism being verified,
the question arises : How are the two forms related 1

For an answer to this question we turn to the life-history, and
what is known on this head will now be given.

LIFE-HISTORY OF POLYSTOMELLA CRISPA — The Microspheric
Form. — The youngest specimens of this form that have been met
with already contained many nuclei. Thus in one, described by
Schaudinn (44, p. 92), with nine chambers, twenty-eight nuclei
were present.

The nuclei are at first homogeneous bodies, but as the animals
grow nucleoli make their appearances. The nuclei are irregularly
scattered through the protoplasm, though they are not found in
the terminal chambers. They are often grouped in pairs, and
there is good evidence that they multiply by simple division (20,
p. 419). The nuclei in the larger chambers are larger than those
in the small chambers near the centre, and they may attain a
diameter of 40-50 p.

In addition to these rounded nuclei, there are generally present
in the protoplasm of the microspheric form abundant irregular
strands of darkly staining substance, which are apparently given
off by the nuclei. In some cases no definite nuclei are visible —

THE FORAMINIFERA

all the stained substance present being in the form of such
irregular strands.

Reproduction of the Microspheric Form. — The first indication of
the approach of the reproductive phase as seen in the living animal

IP,.

-

FIG. 10.

a-c, stages in the reproduction of the microspheric form of Polystomella crispa. Drawn from
photographs of one specimen attached to the side of a glass vessel.

is a great increase in the number of the pseudopodia. They
are so abundant that when the specimen is attached to the side
of a glass vessel and seen by transmitted light, they form a
conspicuous milk-white halo about the brown shell (Fig. 10, a).
The halo is at first composed of clear hyaline protoplasm, but in a

68 THE FORAMINIFERA

short time the coarse brown granules, hitherto contained within
the test, begin to pass out, and ultimately the whole of the proto-
plasm, emerging from the test, is massed within the area covered
by the halo and lies between the test and the supporting surface
(Fig. 10, b). Here, after involved streaming movements, the proto-
plasm gradually and simultaneously separates into spherical masses
of uniform size. The centre of each is occupied by a nucleus, with
an area of clear protoplasm immediately surrounding it. A close
network of delicate pseudopodia surrounds the spheres and forms
a communication between them (Fig 10, c). In a short time each

X • '•

FIG. 10 (conti7iued).

d, later stage in the reproduction of the specimen of Polystomella crispa represented in Fig.
10, a-c.

sphere secretes a calcareous shell, a single small aperture being left
by which the pseudopodia pass out. After lying in close contact
for some hours, the spheres rapidly and simultaneously draw apart
from one another, and within half an hour from the beginning of
the movement they are dispersed over a wide area, and each
becomes the centre of a system of pseudopodia of its own, though
for some time they are not completely isolated (Fig. 10, d).

The whole protoplasm of the parent is used up in the formation
of the brood of young, the shell being left empty. The process,
from the first appearance of the halo to the dispersal of the young,
is complete in about twelve hours.

THE FORAMINIFERA

69

In a short time the protoplasm which lies outside the aperture
of each of the spheres secretes the wall of a second chamber of
characteristic form, and the young individual is then clearly
recognisable in size and shape as the two-chambered young of the
megalospheric form (Fig. 11, b).

The nature of the parent which gives rise to this brood of
megalospheric young is determined by decalcifying specimens
which are entering on the reproductive phase, before the proto-
plasm has left the central chambers. In upwards of fifty cases

m-.c.

FIG 11

Young megalospheric individuals of Polystomella crispa. a, a group of six, two days after their
formation. Four chambers are formed. 6, a specimen with two chambers, decalcified and
stained ; N, the nucleus ; n, irregular stained mass, c, a specimen with nine chambers, simi-
larly treated ; N and n as in 6 ; sp.c, spiral canal of the canal system ; in this specimen it
becomes irregular near the last-formed chamber; m.c, meridional canal.

thus examined the centre was found to be occupied by a micro-
sphere. We have then, in this process, a transition from the
microspheric to the megalospheric form.

Schaudinn (44, p. 94), has found great variation in the size of
the megalospheres produced by one parent, namely, from 10 to 120 /u.
He therefore holds that the two forms of Polystomella, though differing
in their nuclear characters, are not always distinguishable by the size of
the central chambers. He also finds (p. 93) that in some cases the shell
of the young megalospheric form is not secreted until the spherical masses
of protoplasm have wandered about for a long time.

The details of the reproductive process given above are those which I
have invariably observed in specimens which were kept in clean sea-water.

70 THE FORAMINIFERA

In my first observations the water circulating in the tanks of the
laboratory was used ; and though I repeatedly saw the protoplasm
emerge from the parent shell and break up into spheres, the development
did not pursue a normal course. Again and again the spheres, after
remaining separate for some hours, fused with one another, and finally
the mass broke up into irregular globular bodies of very unequal size,
which remained alive for days, but did not, in most cases, secrete a shell.
It was not until fresh sea-water was used in the jars that I had the
pleasure of witnessing the normal process of development.

In view of this experience, and of the fact that though I have ex-
amined some thousands of specimens of Polystomella, I have never met
with a megalospheric form with a central chamber less than 34 p in
diameter, I am inclined to think that the great irregularities in size in
the brood of young, and the small diameter of some of them, are the result
of abnormal development.

In some genera, however, as stated below, the two forms cannot always
be distinguished by the size of the central chamber.

Nuclear Changes. — When, in the reproduction of the microspheric
form, the megalospheres first become isolated, the centre of each is
occupied by a sharply -defined, round nucleus, about 7-8 /* in
diameter, staining uniformly pink in picrocarmine. At this stage
there is also diffused in the protoplasm a material taking a stain
in this reagent; but in a short time the stained material, pre-
viously diffused, becomes aggregated in defined but irregular
masses, which gradually draw together, and for a time frequently
hide the nucleus from view. When two or three chambers of the
young test have been formed the nucleus is again distinctly visible
(Fig. 11, b, N), together with one or more irregular masses (n)
formed by the closer aggregation of the previously diffused
material. In many cases, though not in all, a mass apparently
identical with the latter remains visible in or near the central
chamber in specimens of the megalospheric form in advanced
stages of growth ; but it is, I believe, the round nucleus which
was seen in the megalosphere at its first formation which becomes
the nucleus (" principal kern ") of the megalospheric form.

The relation between this nucleus and the nuclei and irregular
strands of the microspheric parent has not been followed.1

Growth and Reproduction of the Megalospheric Form. — As the
individuals of this form grow, and the number of their chambers
is augmented, the nucleus likewise increases in size, and, leaving
the megalosphere, it moves on through the chambers, becoming
temporarily constricted as it passes through the narrow passages
connecting them. In specimens fairly advanced in growth the

1 I have not met with any evidence in support of Schaudhm's statement
(44, p. 95) that the large nucleus ("principal kern") of the megalospheric form
results from the massing together of the irregular strands of the microspheric
parent.

THE FORAMINIFERA 71

nucleus is, as Schulze pointed out (64, a), usually found in or
near the chamber which is numerically in the middle of the series.

In the cells of growing vegetable tissues the nucleus moves towards that
part of the cell at which growth is most actively proceeding.1 Thus in a
growing root-hair the nucleus is found near the tip ; in a young stellate
hair, it lies at the point of junction of the rays. Its movement towards
the regions of activity results, we must suppose, from a certain force
impelling it in that direction, and its position when at rest is at the point
where the impelling forces, resulting from the activities of the protoplasm
in different parts of the cell, are in equilibrium.

In the forms of Foraminifera in which the nucleus is single it
appears that its position is likewise dependent on the disposition of the
protoplasm. Thus in the megalospheric forms of Cycloclypeus and Orbi-
tolites complanata the nucleus is found in or near the central chamber,
where, owing to the cyclical growth in these genera, the attractions, due
to activity at the periphery, are in equilibrium. In the forms with
spiral arrangement the nucleus moves on through the series of chambers
as growth proceeds. In Polystomella, however, the nucleus of the
megalospheric form always lags some distance behind the point at which,
judging from the disposition of the bulk of the protoplasm, we should
expect the attractive forces to be in equilibrium.

At the earliest stage at which it has been recognised the nucleus
appears to be a homogeneous body. As it grows, round nucleoli
make their appearance, and these are comparatively large in young
specimens, and decrease in size while they increase in numbers as
growth proceeds.

Sections through the nucleus of specimens fairly advanced in
growth show a well-defined nuclear wall, a reticulum with finer
or coarser meshes occupying the interior, and rounded nucleoli at
the nodal points of the reticulum. Minute granules may often be
detected in the strands of the reticulum.

It appears that throughout the vegetative phase of the megalo-
spheric form small fragments are separated off from the nucleus,
and they may often be seen as irregular bodies, sometimes con-
taining nucleoli, lying in the neighbourhood of the nucleus, or in
the chambers through which it has passed in its passage onwards
from the megalosphere.

Towards the end of the vegetative phase of the life-history of
the megalospheric form the nucleus loses its regular outline and
its power of receiving stains, and finally disappears. In such
specimens it may often be observed that additional passages have
been opened up, by the dissolving action of the protoplasm on
the shell substance, between adjoining chambers of inner and
outer convolutions, so that the inner chambers are placed in

1 Cp. Haberlandt's researches, quoted by 0. Hertwig, Die Celle und die Gewebe
i. p. 259.

THE FORAMINIFERA

more direct communication with the outer, and so with the
exterior.

Eeproductive Phase of the Megalospheric Form. — In specimens in
which the large nucleus has disappeared hosts of minute nuclei
may be found, scattered uniformly or in groups through the
protoplasm.

Presumably these are derived from constituents of the principal
nucleus, and possibly of the small nuclear fragments as well, but
their precise relation to these bodies has not been followed.

When the nuclei are evenly distributed the protoplasm breaks
up into minute rounded masses, the centre of each being occupied
by a nucleus. Division of these nuclei by karyokinesis now occurs,
and is simultaneous or nearly so throughout the organism, and
this is followed by a second division of the protoplasm to form
rounded bodies about 3-4 //, in diameter, each containing one of the
daughter nuclei (Fig. 12). At a later period the contents of the

shell issue as active zoospores
of approximately uniform size,
which swim rapidly by means of
flagella.

It is to be noted that, as in
the case of the reproduction of
the microspheric form, the whole
of the protoplasm of the parent
is used up in the production of
the zoospores.

Though the zoospores have
been seen issuing from the
shell, their precise characters,
when ripe, have not been accur-
ately described ; nor have we as
yet direct evidence as to their
fate.

That there is a close relation
between the zoospore and the
microsphere is suggested by the fact that there is no great differ-
ence in size between these structures, the diameter of the former,
before their escape from the parent shell, being 3-4 //,, and that of
the latter about 10 /z. A further piece of evidence tending in
this direction is furnished by an observation of Schaudinn's (44,
p. 92). In an aquarium containing abundant Polystomellas,
Schaudinn suspended coverslips by means of threads, so arranged
that the lower borders of the coverslips were separated by about
2 cm. from the stratum covering the bottom of the aquarium.
After two days young examples of the microspheric form were
found on the coverslips. Now throughout the vegetative phases

Section through a specimen of the niegalo-
spheric form of Polystomella crispa, in which the
contents are divided up into zoospores. x 160.

THE FORAMINIFERA 73

of its life Polystomella crawls over the surface of submerged objects,
by means of its pseudopodia, but is incapable of swimming freely ;
and as the depth of 2 cm. far exceeds the distance to which the
pseudopodia of so young a specimen are likely to extend, the
colonisation of the coverslips by the microspheric form under
these conditions points to the existence of a free swimming
stage prior to the vegetative stage in which the young forms
were found. Such a stage is supplied by the free swimming
zoospore.

The results furnished by direct observations on the life-history
of Polystomella may be summarised in two statements : —

The microspheric form terminates its existence by becoming trans-
formed into a brood of megalospheric young.

The megalospheric form terminates its existence by becoming trans-
formed into minute zoospwes of uniform size,

Before discussing the bearing of these results on the relation-
ship of the microspheric and megalospheric forms, it will be con-
venient to consider some facts in another life-history, that of
Orbitolites complanata.

LIFE -HISTORY OF ORBITOLITES COMPLANATA. — The main
features of the structure of this species are described below (p.
104 and Figs. 36 and 37). For the present purpose it will be
sufficient to point out that the mode of growth is, except in the
early stages, cyclical, concentric rings of small chambers being
added at the margin of the disc-shaped test, and that the tests
are biconcave. In the microspheric form the central region is
thin, being built up of the microsphere and the small chambers or
" chamberlets " which succeed it.

In the megalospheric form the centre of the shell is thicker
owing to the presence of the " primitive disc " (Figs. 37, A, and 38).
This consists of the megalosphere, a spiral passage, and of the
very large crescentic chamber, which nearly surrounds the other
constituents of the primitive disc. The outer margin of the
crescentic chamber is perforated by pores, by which it opens into
the innermost ring of chamberlets.

Reproduction. — The production of megalospheric young by a
microspheric parent has been repeatedly observed (4 and 20, and
Fig. 36, b). In the later stages of the growth of the parent
spacious brood chambers are formed at the periphery of the disc,
and in the reproductive phase the protoplasm is withdrawn from
the small chambers internal to them and massed in the brood
chambers, where it breaks up to form the brood of young. On
their escape, which is effected by the breaking down of the outer
walls of the brood chambers, presumably under the dissolving
action of the protoplasm of the young, the test of each young
individual has already the structure of the " primitive disc "

74 THE FORAMINIFERA

which is found at the centre of the megalospheric form (Figs. 37,
A, and 38).

This process is clearly comparable with the formation of the
megalospheric young by a microspheric parent which we have
followed in Polystomella, the chief difference consisting in the fact
that the young are formed in peripheral brood chambers and not
outside the test of the parent.

By analogy with Polystomella we cannot doubt that megalo-
spheric parents give rise to zoospores. Specimens of Orbitolites
have, however, been found (and the corresponding phenomenon
has also been observed in several other genera) in which a
brood of megalospheric young occupies the peripheral chambers
of a test, the centre of which is formed by a primitive disc, and
which is therefore megalospheric (20, p. 435). Hence we must
conclude that in these cases the megalospheric form may be
repeated, possibly more than once, before a brood of zoospores

is produced. The behaviour of the
nucleus under these conditions has
^ •© not been closely followed.

& gj _ Fig. 13 illustrates a similar repe-

tition of the megalospheric form in
the case of Cornuspira involvens.1

The Relation between the Microspheric
and Megalospheric Forms.

With the evidence furnished by
the life -histories of Polystomella and
^^fnsp^ra inv^ wnt' .Reuss- ,The Orbitolites we may now return to the

contents of a megalospheric form have J

emerged from the shell and divided up question of the relationship of the

into a number of young, which are also TV.- j i_ • r

megalospheric. in bSth parent and megalospheric and microspheric forms.

young the megalosphere was about TViP Parlipor VI'PW liplrl nn this

80 n in diameter, x 30. Cp. Fig. 20. earliest V16W J

subject, that they represented two

species of a genus, is at once disposed of by the fact that the
megalospheric form is the offspring of the microspheric.

The next suggestion was that the two forms represent the two
sexes.

To this, two objections may be made on general grounds.
(1) The difference between them is most marked at the beginning
of their growth, when they consist only of the central chambers,
the microsphere or the megalosphere, while males and females

1 In his preliminary paper Schaudinn states (44, p. 96) that the megalospheric
generation may also be repeated (though rarely) in Polystomella, and that in such an
event- no principal nucleus is formed by the megalospheric parent. As Rhumbler
remarks in his notice of Schaudinn's paper (Zool. Centralblatt. Jahrg. 2 (1895),
p. 453, footnote), it is difficult to see how this result can be reached, for the shell of
Polystmnella is too thick to allow the nuclear condition to be observed during life.

THE FORAMINIFERA 75

arise from eggs which are, so far as observation has yet advanced,
similar, and are most differentiated when adult. (2) Although
the differentiation of male and female gametes is known in several
groups of the Protozoa (Sporozoa, Ciliata, Flagellata), a differentia-
tion of the parent organisms which produce the gametes, which
would be the phenomenon comparable with the sexual dimorphism
of the Metazoa, is unknown among the Protozoa.

But apart from a priori objections, it may be well to try how
the ascertained facts of the life-history fit this hypothesis. The
megalospheric form, producing zoospores, would evidently on this
view represent the male, while the microspheric form, producing
the large megalospheres, might be regarded as the female. It
might be supposed, the fate of the zoospores being unknown, that
they unite with and fertilise the megalospheres. But while the
origin of the megalospheric form, the supposed male, is thus
accounted for, that of the microspheric form, the supposed female,
remains unexplained, and as the whole of the protoplasm of the
parent is, to all appearance, used up in the brood of megalospheric
young, the hypothesis is at fault. Moreover, in Orbitolites,
Cornuspira, and other genera the megalospheric form may also give
rise to a brood of megalospheric young, a proceeding foreign to
the nature of a male organism. Hence neither of the forms of the
species conforms to the character assigned to it by the hypothesis :
the microspheric form, the supposed female, in that it does not
produce " females " ; the megalospheric form, the supposed male, in
that it does in some instances produce " males."

A third hypothesis is in harmony with what we know in other
groups of the Protozoa, and fits the ascertained facts. It is that
the two forms represent alternating or recurring generations in a
life-cycle. The individuals of the microspheric form reproduce
asexually by the multiple fission of their protoplasm to form broods
of megalospheric young. The individuals of the megalospheric
form may undergo, in some genera, a similar process, but ulti-
mately a megalospheric individual is produced whose protoplasm
divides into zoospores.

How is the gap between the zoospore and the microsphere
filled 1

That they are closely related is suggested, as stated above, by
their approximation in size, and by the indication, afforded by the
colonisation of Schaudinn's coverslips, of a free swimming stage
preceding the vegetative phase of the microspheric form. Another
remarkable fact bearing on the matter is the scarcity of the micro-
spheric form in comparison with the megalospheric, a scarcity all
the more striking when it is borne in mind how far more numerous
are the zoospores produced by one megalospheric individual than
the members of a brood of megalospheres.

76 THE FORAMINIFERA

The analogy of other life -histories would lead iis to suppose
that at some point in the cycle a sexual process, the conjugation,
with nuclear fusion, of two organisms, occurs, and the life-history
of Trichosphaerium sieboldi, Schn., which has lately been worked
out by Schaudinn (47), to whom so much of the recent advance
in our knowledge of the life -history of the Protozoa is due,
appears to afford a very appropriate parallel. This form is
not included in the Foraminifera, but is a somewhat aberrant
member of the allied group — the Lobosa. The main features
of its life- history are, however, remarkably similar to those of
Polystomella.

The individuals are rounded multinucleated masses of proto-
plasm not contained in a definite shell, though surrounded by a
gelatinous envelope. They form a dimorphic series, the members
of which recur in a cycle of generations. In those of one genera-
tion, which may be called by Haeckel's term Amphionts, reproduc-
tion occurs by the simultaneous division of the protoplasm about
the nuclei to form spherical uninucleated masses, which emerge
and grow into the members of the other generation — the Mononts.
These in their turn break up, after subdivision of their nuclei, into
zoospores. The zoospores are biflagellate organisms, and are all
alike.

While the zoospores from the same parent will not unite with
one another, those from different parents conjugate readily. In
this process, which has been carefully followed by Schaudinn, the
nuclei of the two gametes unite, their flagella drop off, and the
zygote so produced, absorbing fluid, undergoes a considerable in-
crease in size, so that in a few hours its diameter is more than
doubled. The zygote shortly afterwards secretes a gelatinous
envelope, and the characters of the full-grown individual of the
amphiont generation are gradually acquired. The multinucleate
condition results from successive mitotic divisions, beginning with
that of the nucleus of the zygote.

In Hyalopus dujardinii, which may be regarded as a member,
though an aberrant one, of the Foraminifera, Schaudinn (43) has
also observed the conjugation of zoospores, but in this case the
process occurred between members of the same brood.

If we assume that a similar conjugation of zoospores occurs in
Polystomella, the facts above alluded to are at once explained.

The fusion of two zoospores (4 p. in diameter), and the subse-
quent expansion of the zygote by the absorption of water before
the secretion of a shell, might well form a body of the size of the
microsphere (about 1 0 p.) ; the free locomotive stage prior to the
settling down of the microsphere, indicated by Schaudinn's
experiment, is supplied ; and the comparative rarity of the micro-
spheric form is explained on the supposition that, as in Tricho-

THE FORAMINIFERA 77

sphaeriwn, the meeting and conjugation of zoospores from different
parents is necessary for the production of a microsphere.

It is very desirable that the conclusion should be confirmed
by direct observation, but, meanwhile, it seems not premature to
admit that it is probable that the microsphere arises from the
conjugation of zoospores.

We may conclude, then, that the microspheric and megalo-
spheric forms of the Foraminifera represent alternating or re-
curring generations in a life -cycle. While the megalospheric
generation arises asexually, either from a microspheric or a megalo-
spheric parent, it is probable that the microspheric generation
arises sexually — i.e. by the conjugation of two similar zoospores.

Representatives of the two generations have been recognised
in species belonging to the following genera of Foraminifera : —

ORDER 1. Gromiidea (7).1
( „ 2. Astrorhizidea.2)
( „ 3. Lituolidea.)
„ 4. Miliolidea.

Family MILIOLINIDAE. — Cornuspira (24, 1898, p. 612); Spiro-
loculina (57, p. 201); Biloculina (27, p. 863); Sigmoilina (Planispirina,
pars), Schl. (53, p. 106) ; Triloculina and Quinqueloculina (27, pp. 863
and 1598); Massilina (57, p. 218); Adelosina (52, p. 91); Idalina
and Periloculina (28) ; Lacazina (27).

Family HAUERINIDAE. — Planispirina, Seg. (56, p. 194).

Family PENEROPLIDIDAE. — Peneroplis and Orbiculina (this article),
Orbitolites (4, p. 693, and this article) ; Meandropsina (59).

Family ALVEOLINIDAE. — Alveolina (51, p. 526).

ORDER 5. Textularidea.
Family TEXTULARINAE. — Textularia and Spiroplecta (this article).

(ORDER 6. Chilostomellidea.)
„ 7. Lagenidae.

Family NODOSARIIDAE. — Nodosaria and Dentalina (51, p. 526;;
Frondicularia (15, p. 480) ; Cristellaria (?) (5, p. 45).

Family POLYMORPHINIDAE. — Siphogenerina (Sagrina) (50, p. 21).

(ORDER 8. Globigerinidea.)
„ 9. Rotalidea.

Family ROTALIDAE. — Eotalia (51, p. 526, and 20, p. 436);
Truncatulina and Calcarina (20, pp. 436 and 437).
Family TINOPORIDAE. — Polytrema (23).

1 The cases of Hyalopus and Mikrogromia are considered below.
" In the orders included in brackets I have not succeeded in finding a record of
the existence of dimorphism.

78 THE FORAM1NIFERA

ORDER 10. Nummulitidea.

Family FUSULINIDAE. — Fusulina (58, p. 1).

Family POLYSTOMELLIDAE. — Polystomella (20, p. 415).

Family NUMMULITIDAE. — Operculina (this article); Amphistegina
(51, p. 526) ; Nummulites and Assilina (26, p. 300) ; Heterostegina (this
article); Cycloclypeus (10, p. 21, and this article); Orbitoides (31, p.
258, and 61, p. 463) ; Miogypsina (60, p. 328).

Thus the phenomenon of Dimorphism, the occurrence of mem-
bers of a species under two forms — the megalospheric and micro-
spheric — is widely spread among the orders of the Foraminifera,
and where it is found it affords clear evidence of alternating or
recurring generations in the life-history of the species exhibiting it.

REVIEW OF THE STRUCTURE AND LIFE-HISTORY DISPLAYED
IN THE ORDERS OF THE FORAMINIFERA.

As the attention of the many workers who are occupied with
this group is turned to the subject, the list of dimorphic forms
will, no doubt, be greatly extended ; but there are indications in
the descriptions already published of phases in the life-history of
some forms, especially in that borderland occupied by the simpler
Foraminifera, which depart in a greater or less degree from those
described in Polystomella and Orbitolites ; and we may now take a
survey of the features of life -history which have been described
in the different groups, and of the more interesting modifications
in the form of the test, which, as we have seen, is found to be
more or less dependent on the phase of the life-history of the
organism which secretes it.

In chambered tests, in which the walls of the first formed
chamber remain unaltered throughout growth, evidence of the
mode of origin of the individual, whether as a megalosphere or a
microsphere, is furnished by the structure of the test. But in the
great majority of the Gromiidea and Astrorhizidea, the tests expand
to accommodate the increase by growth (cp. p. 54), and all in-
dications of the size of the test when it was first secreted are
obliterated. Hence we are deprived in them of part of the evidence
on the course of the life-history which we have in other groups,
and we must rely on the characters furnished by the soft parts
of preserved specimens, or on direct observation of the living
animals.

From the evidence which we have, however, it is not clear
that the course of the life-history of some members of these orders
is the same as that of the dimorphic Foraminifera above described.

THE FORAMINIFERA

79

ORDER Gromiidea.

In Euglypha (Fig. 3) multiplication, by division into two,
occurs as follows.1 The specimen which is about to divide
secretes fresh shell plates, which are at first dispersed in the
protoplasm about the nucleus. The pseudopodia are with-
drawn, and the protoplasm is extruded beyond the mouth of the
test in a rounded mass. This grows until it assumes a size
equal to that of the test from which it protrudes, and the
newly-formed plates are disposed on the surface to form a new
test. The nucleus divides by karyokinesis, half going to each
end of the mass, and division of the protoplasm follows, one part
remaining in the old shell and the other in the new one.

Fro. 14.

Colony of Mikrogromia socialis in the diffused condition, a, an individual in process of
multiplication by transverse fission, c.v, contractile vacuole. Two of the members of the
colony are seen to be undergoing the same process.

Blochmann (2) has described a process in which, after the
division of the nucleus, the protoplasm was withdrawn from the
newly formed shell, and this, together with the daughter nucleus
remaining in it, was cast off. It is suggested that this may be
comparable with the extrusion of parts of the nucleus observed in
some other Protozoa and in polar-body formation. But in view
of the fact that the new shell was cast off, as well as the daughter
nucleus, this interpretation appears, to say the least, forced.

A temporary fusion of the protoplasm of two or more indi-
viduals, apparently without fusion of nuclei (plastogamy), was
observed by Blochmann, and in one instance a new individual was
apparently formed by the conjugation of two. In this case it

1 The process was first described by Gruber (16), and followed out in detail by
Schewiakoff (48).

8o

THE FORAMINIFERA

\

was supposed that the nuclei had united (karyogamy) as the new
individual was uninucleate.

Encystment also occurs in Euglypha, but what the subsequent
stage may be is unknown.

Mikrogromia socialis, first described by Archer,1 and afterwards
more fully by R. Hertwig (18), is a fresh-water form, occurring in
colonies, the members of which are united by their pseudopodia.
The colonies are sometimes globular and compact (Cystophrys
stage), sometimes diffused (Fig. 14), and in the latter condition
present an interesting resemblance to a brood of young megalo-
spheric individuals of Polystomella in a stage of dispersal
(Fig. 10, d).

The growth of the colony results from the partial longi-
tudinal fission of the members into two (or three), one (or two) of

the products of fission escaping,
secreting a new test, and taking its
place in the colony. Hertwig also
observed the production of young
individuals, arising by transverse
fission (Fig. 14, a). Of the two bodies
so formed one remains in the test,
continuing the vegetative phase of
the parent, the other becomes free,
and, in some cases, swims away as
a biflagellate organism. In other
cases, however, the flagella were not
observed, being replaced by pseudo-
podia, resembling those of Actino-
phrys. The further history of the
young thus produced was not
followed. Assuming this to be a
normal phase of development of
Mikrogromia, it appears to be with-
out a parallel in the life-history of
Polystomella.

Hyalopus dujardinii, Schaudinn
( = Gromia dujardinii, M. Schultze) is
a marine form distinguished by the
hyaline and nongranular character of
its pseudopodia, and by the absence
of anastomoses between their branches.
The main body of the protoplasm is
covered by a chitinous envelope, and contains large brown
rounded granules and many nuclei. In the condition in which it

FIG. 15.

Hyalopus (Gromia) dujardinii.
(After M. Schultze.)

X 40.

1 Provisionally as two species, Cystophrys haeckeliana and Gromia socialis
Archer (1).

THE FORAMINIFERA

81

FIG. 16.

nuc
Arcbe

5, Siiepheardella taeniformis, Siddall, x about 10. (After Siddall, Q.J.M.S-uvol. xx.) The
sleus is seen nearly opposite 5. 11, Amphitrema wrightiamiin, Archer, x about 210. (After
cher, Q.J.M.S., N.S. vol. ix. 1869.)

82 THE FORAMINIFERA

was described by M. Schultze (64, p. 55), the shape is oval, and
there is a single orifice (Fig. 15), but Schaudinn finds (43) that
when living amongst the stems of algae, it loses its oval shape
and assumes a branching form, new mouths being developed at
the ends of the branches. Such branched forms may attain a
length of 5 mm.

Two modes of reproduction were observed. One is by a
process of fission, the body slowly dividing into two or three
parts, sometimes of unequal sizes ; the other is by the formation
of zoospores. In the latter process the pseudopodia are retracted
and the whole protoplasm divides up into oval or pear-shaped
bodies, 5-8 p. in diameter, containing a nucleus 3-6 p. in diameter,
a vacuole, and a conspicuous granule. They swim by means of
a single flagellum 30-38 //, in length.

The zoospores conjugate in pairs, but in this case the conju-
gation is, according to Schaudinn, between members of the same
brood. The further history of the zygote could not be followed.

The formation of the zoospores of Hyalopus is evidently com-
parable on the one hand with the reproduction of Trichosphaerium
which gives rise to the "amphiont" generation, and on the other
hand with the reproduction of the megalospheric form of Polysto-
mella.

A similar mode of reproduction to the slow process of fission
of Hyalopus has been seen in Lieberkiihnia and Lecythium, the
division of the protoplasm involving that of the envelope. Whether
this is to be compared with the production of the brood of
melagospheres by the multiple fission of the microspheric parent,
or to the similar slow fission which occurs in Trichosphaerium in
addition to the multiple fission of the "amphiont" parent, it
appears to be at present impossible to decide. Many of the
Gromiidea have a single orifice to the test, as in Gromia and
Euglypha (Figs. 1 and 3). Shepheardella and Amphitrema have two
orifices, situated at either end of a median axis (Fig. 16, 5 and ll).

ORDER Astrorhizidea.

In Saccammina, and some other members of the Astrorhizidea
in which growth is accompanied (as explained above, p. 54) by
expansion of the test, no evidence on the phase of life-history
represented, is furnished by its structure. But in other genera,
such, for example, as Hyperammina, in which the tests grow not
by expansion, but by addition, a large globular chamber is some-
times found at the commencement (Figs. 17, d, and 18). Such
forms may well represent a megalospheric generation. There
is, however, no evidence at present of the microspheric forms
corresponding to them.

Rhumbler has made a careful investigation (33) of the nuclear

THE FORAMINIFERA

characters of Saccammina sphaerica (Fig. 17, b). He found that
among the 286 specimens which he examined, a single nucleus
was present in all but one
(which had two nuclei, and
was regarded as abnormal),
and the phases presented by
the nuclei fell into a con-
tinuous series. They corre-
spond with those of the nucleus
of the megalospheric form of
Polystomella. The nucleus in-
creases in size with the growth
of the organism, and the
nucleoli ("binnen korper"), at
first large and few, increase
in number and diminish in
size. Finally (PI. 23, Fig. 67)
the nuclear membrane breaks,
and linin threads containing
chromatin grains are dispersed
in the protoplasm. From these

FIG. 17.

a, Astrorhiza limicola, Sandahl., x 6. b, Saccammina sphaerica, M. Sars, x!2. c, Pilidina
je/reysii, Carpr., x 12. d, Hyperammina subnodosa, Br., x 7. In a, b, andrf the test lias been
laid open. (From Brady, "Challenger" Report.)

later nuclear phases it appeared that some process of reproduction
was imminent, but none was observed. The formation of zoospores
by the Foraminifera was at that time unrecognised, and Rhumbler

84

THE FORAMINIFERA

was surprised at finding no indication, notwithstanding the
abundant material at his command, of the formation of a brood of
young resembling the parent. On the analogy of the life-history
of Polystomella, the absence of such indications appears in no way
remarkable, for such a nuclear history is associated, as we have
seen, with the production of zoospores.

The only difficulty in applying this analogy arises from the
fact that no indications were found of a form of Saccammina with

a different nuclear history,
corresponding with that of
the microspheric generation of
Polystomella.

It is, of course, possible
that the microspheric form,
although occurring in nature,
did not happen to be repre-
sented among the specimens
examined; but however this
may be, it is clear that we are
not at liberty to assume the
existence of a microspheric
form in Saccammina. Hence,
in the absence of other evi-
dence bearing on the point,
the Astrorhizidea cannot at
present be admitted into the
list of dimorphic Foramini-
fera.

In Haliphysema tumano-
wiczii (Fig. 19) Lankester (19)
described numbers of " egg-
like " bodies, varying in diam-
eter from y-Vo- to -g-J-g- inch,
scattered through the proto-

Hyperammina arborescens, Norm, a, two speci- plasm. They appeared to be
mens growing attached to a stone, x 20 ; o, initial 1 i •

chamber of another specimen. (After Brady.) nucleated, and, in SOHie CaSCS,

in process of division. It was

surmised that they might be concerned in reproduction. Further
information on the nature of these bodies would be very accept-
able, but the possibility appears not to have been excluded that
they are symbiotic or parasitic organisms similar to those which
abound in the protoplasm of Orbitolites complanata.

Via. 18.

THE FORAMINIFERA

ORDER Lituolidea.

This order consists of arenaceous forms which are "isomorphic"
with genera belonging to several of the other orders; and by
many authors the order is broken up, and its genera associated

10

Fio. 19.

Haliphysema tumanowiczii. 10,
part of the protoplasm stained to
show the nuclei, n ; 11, living speci-
men with expanded pseudopodia.
(From Lankester, Art. Protozoa,
Encycl. Britannica, Fig. x.)

with the calcareous forms which they resemble. In some cases
(e.g. Cornuspira, Nodosaria, Rotalia) the latter are, as will appear
below, dimorphic, so that we should expect their " isomorphs " to
be so likewise ; but though this is very probably the case, I am
aware of no direct evidence on the matter.

A process of reproduction is recorded by Schaudinn (42) in
Ammodiscus gordialis, P. and J. The protoplasm divides within
the parent test into some 50-80 young, which become invested

86

THE FORAMINIFERA

with a chitinous envelope, together with siliceous particles pre-
viously taken into the protoplasm.

ORDER Miliolidea.

On coming to the Miliolidea we have a large body of evidence
on dimorphism, thanks in great measure to the careful investiga-
tions of Schlumberger, by whom, either alone or in conjunction
with Munier-Chalmas, the foundations of our knowledge on the
dimorphism of the tests of Foraminifera have been laid. The tests
will first be described, the nuclear characters and such details of
the life-history as are to hand being given at the end.

Family Miliolinidae. — Before considering the phenomena of
dimorphism in this family, it is necessary to describe the character-
istic structure of the test in certain forms.

FIG. 20.

Comuspira involvens, Keuss. a, the megalospheric
form, x 90. b, the microspheric form, x 50. (From
Brady, Parker, and Jones, Trans. Zool. Soc. vol. xii. PI.
40, Figs. 1 and 2.)

FIG. 21.

Splroloculina limbata, d'Orb.,
x 30. (After Brady.)

The simplest type is met with in Comuspira.

The whole of the test except the central chamber (which pre-
sents a well-marked difference in size in the two forms, Fig. 20)
consists of a continuous tube, gradually increasing in diameter as
it is followed away from the centre, but without any constrictions
dividing it into separate chambers. In both forms it is disposed
in a closely-wound spiral lying in one plane, so that a section in
this plane would divide the test symmetrically.

In the genus Spiroloculina the arrangement is somewhat similar,
but here the tube is divided into distinct chambers, each of which
ends in a contracted mouth with an everted lip. The chambers
increase successively in length, and are so disposed that each
occupies half a turn of the spiral. It results from this arrange-
ment that the mouths of the chambers are directed alternately in
opposite directions, and each chamber is applied to that which is
next but one before it in the series. A straight line, which passes

THE FORAMINIFERA

through the central chamber and the mouths of all the chambers
which succeed it, has been called the axis of construction. The
spiral formed by the series of chambers is not quite regular, as is
the case in Cornuspira ; for while each chamber is gently curved,
there is a sharp bend where one chamber communicates with
another. Hence the test is elongated in the axis of construction.
In Spiroloculina the chambers are disposed in one plane, and the
width of each is only slightly greater than that of its predecessor,
so that all the chambers are exposed on the two flat faces of the
test (Fig. 21).

In all but the earlier chambers of the microspheric forms the
arrangement characteristic of the genus Biloculina is essentially
similar, but there is a marked difference in the shape and appear-
ance of the test owing to the great width of the chambers. Each

FIG. 2-2.

a, Biloculina depressn, d'Orb., X 40. 6,
Triloculina tricarinata, d'Orb., x 50. (After
Brady, 3.)

is so wide that its margins are in contact with those of its prede-
cessor, and overlap them at the sides (Figs. 22, a, and 24). It results
from this arrangement that the two last chambers enclose those
previously formed, and they alone appear in the contour of the
test. As in the preceding genus a median longitudinal section
through the last chamber divides the whole series of chambers
into symmetrical halves. As will appear later, the microspheric
form of Biloculina departs considerably from this arrangement.

In Triloculina and Quinqueloculina1 the chambers are likewise
disposed about an axis of construction, and their mouths open
alternately in opposite directions, but the median plane of any
chamber is not that of its predecessor, but directed at a definite
angle to it. It is as though in a Biloculina test, while the plane
in which the new chambers are formed remains constant, the

1 These genera are now usually included in the genus Miliolina, though Schlum-
berger is inclined to retain the old generic distinctions.

THE FORAMIN1FERA

FIG. 23.

Quinqueloculina seminulum, Linn, a-c, views of test ; a, b, from the sides ; c, from apertural
end. A, section of megalospheric, B, of microspheric form. A and B from Schlumberger (57).
It will be noticed that A and B represent a less flattened form of test than that seen in a-c.

THE FORAMINIFERA 89

part of the test already formed were to rotate on its axis of con-
struction through a definite angle in the interval between the
formation of one chamber and the addition of its successor. In
the genus Triloculina the rotation is through (approximately) one-
third of the circumference, in Quinqueloculina through two-fifths,
and the chambers are disposed in three and five radii respectively.

In these genera the width of the chambers is, moreover, less
than in Biloculina ; and in Triloculina three, in Quinqueloculina five
chambers are exposed, at any given stage of growth on the contour
of the test.

We may now turn to the phenomena of dimorphism as pre-
sented by members of this family.

In representatives of all the genera included in the list on
p. 77, a well-marked difference has been shown to exist in the
size of the central chamber in the two forms of the species. Thus
in Biloculina depressa the diameter of the megalosphere (M) l has
been found to vary from 200 to 400 //,, and that of the micro-
sphere (m) l from 18 to 25 p (Fig. 24).

In B. ringens the contrast is not so great (M= 54 p, m = 20 p,).
In Triloculina M = 204 /z, m = 18 p. In Sigmoilina M= 96-150 /*,
w = 27-36 p. In Adelosina M = 90-330 /*, m=\S p. In Idalina
M= 180-440 n, m=l2 /z. In Massilina a well-marked difference
is said to be present, though the actual dimensions are not
recorded.

Turning to the plan of growth, in Cornuspira and Quinquelocu-
lina the tests are uniform, i.e. they are arranged on the same
plan throughout, from the part which immediately succeeds the
central chamber to the end of the test ; and this is the case in
both forms of the species. Massilina has biformed tests in both
megalospheric and microspheric forms, the earlier chambers being
arranged on the quinqueloculine plan, and the later on the spiro-
loculine. But in several of the other genera a marked contrast is
found in the arrangement of the chambers in the megalospheric
and microspheric forms. In the species of these genera the tests
of the megalospheric forms are, for the most part, uniform, the
arrangement characteristic of the genus being followed throughout
the growth of the test, while the tests of the corresponding
microspheric individuals are bi- or tri-formed, the plan of growth
of the chambers changing once or twice before the test is
complete.

Thus in many species of Biloculina the arrangement of the
megalospheric form is biloculine throughout (Fig. 24, a). In the

1 It will be convenient to use the letters M and m to indicate the diameters of the
megalosphere and microsphere respectively, the " diameter " being taken to imply,
when the central chamber is not spherical, the mean between the long and short
diameters.

THE FOR A MINI PER A

microspheric form (Fig. 24, b) the chambers succeeding the micro-
sphere are arranged on the quinqueloculine plan, and this arrange-
ment is maintained during the addition of a smaller or larger
number of chambers, according to the species. At a certain stage
the chambers become wider, and conform to the triloculine plan.
Finally, the biloculine arrangement is assumed and maintained
during the remainder of growth.

In like manner the megalospheric forms of Triloculina are built

Fm. 24.

Biloculina ilepressa, d'Orb. Transverse sections, a, of the megalospheric form, x 50. 6,
of the microspheric form, x 90. (Two external chambers have been omitted in 6.) (After
Schlumberger, 55.)

I am indebted to the Cambridge Philosophical Society for permission to use the block from
which these figures are prepared.

up on the triloculine plan throughout, while the microspheric forms
begin life on the quinqueloculine plan, though they conform early
to the triloculine (Fig. 25).

In some species it appears that a difference in the arrangement of the
chambers is maintained throughout the growth of the test. Thus in
Biloculina lucernula, Schwager, the microspheric form, commencing on the
quinqueloculine plan, becomes triloculine, but appears never, according to
Schlumberger, to attain to the biloculine arrangement, which the megalo-
spheric form follows throughout. The two forms are shown to belong to
the same species by similarities in the shape of the chambers, and also

THE FORAMINIFERA

by the presence of a thin sandy layer on the surface of the test, which
none of the other species inhabiting the same locality possess (55).

A difference in the arrangement of the chambers throughout growth
is also said to be found in Adelosina polygonia, Schlumb., but it is in part
of a different character. In this species the chambers are all arranged in

Sections of the test of Trilomlina schreiberia.ua, d'Orb, x 66. a, the megalospheric form.
Z>, the microspheric form. (After Schlumberger, 57.)

a single plane in the megalospheric form, and after a preliminary
quinqueloculine phase they are arranged in a single plane in the micro-
spheric form. So far the arrangement agrees with that of Biloculina.
But the chambers of Adelosina polygonia do not occupy a half turn of the

FIG. 20.

Adelosina polyyonia. a, the megalospheric form ; b, the microspheric form, x about 20
(After Schlumberger, 54.)

spiral, as do the chambers in that genus, but only one-third or a quarter
of a turn. In the microspheric form each chamber occupies one quarter
of a turn of the spiral, and the tests are, in consequence, quadrangular in
outline. In the megalospheric form the chambers occupy each one-third
of a turn, and the resulting tests are triangular (Fig. 26). In about 1 per
cent of the individuals of this form, however (310 were examined), the
quadrangular arrangement was adopted in the last whorl (54).

THE FORAM1NIFERA

In the Miliolinidae, then, the tests of the megalospheric and
microspheric forms of a species differ in the size of the central
chambers, and also in some cases in the arrangement of the
chambers which immediately succeed it. When this difference is
found it depends on the fact that while the megalospheric form
generally grows on a uniform plan throughout, the microspheric
form assumes for a longer or shorter period of its growth an
arrangement different from that to which it subsequently con-
forms, and one which is, in many cases, characteristic of another
genus of the group.1

The term Initial Polymorphism was first applied by Munier-
Chalmas and Schlumberger to a varying condition with respect
to the arrangement of the initial chambers observed among
different individuals of the megalospheric form of the fossil
Idalina antiqua. It occurs also, as we shall see, in other genera.

FIG. 27.

The central regions of transverse sections of three examples of the megalospheric form of
Idalina antiqua (d'Orb.). Diameter of megalosphere in a=440, 6=400, and c=240 jx. After
Schlumberger. (It will be observed that the magnification of a is greater than that of 6 and c.)

In this species the megalospheric and microspheric forms are
sharply contrasted in the size of their central chambers
(M = 180 - 440 p,, m = 12 /A), and the arrangement of the chambers
is, in the main, that characteristic of Biloculina. The microspheric
form passes through quinqueloculine and triloculine stages to a
biloculine condition, which, however, is converted in this genus in
the later stages of growth to a uniloculine state, by the lateral
extension of each of the chambers in turn, to embrace the whole of
the previously formed test. The megalospheric form begins in
many cases (Fig. 27, a), on the biloculine plan, to become unilocular
at a later stage, like the microspheric form. In some cases,
however, the initial chambers of this form are arranged on the
triloculine plan (6), and in others again on the quinqueloculine
(c), though the biloculine arrangement is soon assumed, in the
latter case with a brief intermediate triloculine phase. Moreover,

1 I am not, however, aware of any definite form which the microspheric tests of
Addosina polygonia resemble.

THE FORAM1NIFERA

93

and it is important to notice this point, the forms with the largest
megalospheres are those which assume the biloculine condition
directly ; those with the smaller megalospheres repeating the
triloculine or the quinqueloculine arrangement.

Family Hauerinidae. — The biformed genera brought together
in this family are said to be characterised by the cornuspira-like
or milioline (tri- or quinque-loculine) arrangement of the chambers
in the early stages of growth. In some cases, however, as in
Articulina conico-articulata, Batsch, two forms of a species occur, one
beginning in a large globular chamber with
a short spiral passage leading to the later
chambers, which are disposed in rectilinear
series (Fig. 28, a), the other with a group
of milioline chambers at the beginning
(Fig. 28, b). It appears probable that
these represent the two forms of the
species, comparable with those found else-
where.

Family Peneroplididae. — Four genera
are here included — Peneroplis, Orbiculina,
Orbitolites, and the fossil Meandropsina. As
Carpenter pointed out, there is in this sub-
family a well-marked series of forms with
varying degrees of complexity of structure.
Moreover, the contrast in the arrangement

<• ,i 111 • xi_ r r

of the early chambers in the two forms of

the species (that of the microspheric forms

is here, I believe, described for the first time)

appears to offer an instructive parallel to that met with in the

Miliolinidae and elsewhere. Hence the group will be rather fully

described.

Peneroplis is represented by a single species (P. pertusus,
Forsk.) presenting, within certain limits, a remarkable range of
variation.1 In all cases the chambers are simple. During the
earlier stages of growth they are disposed on a planospiral plan,
and this may be followed until the test is complete, but more
usually the terminal chambers are disposed in a rectilinear series.
The width of the later chambers varies very much, as seen in the
" crozier-shaped " and broad tests represented in Fig. 29.

Another varying feature is the " equitant " character of the
chambers, as the result of which the earlier convolutions of the
spiral part of the test are overlapped and hidden in varying
degrees by the alar prolongations of the chambers which succeed
them. The first few chambers communicate by single apertures,
but the apertures soon become compound, consisting of a single or
1 Cp. for the superficial characters of the tests, Dreyer (13).

Flo. 28.

Articulina conico-articulata,
Batsch. x about 55. a, from
pt. ii.). 6, from

94

THE FORAMINIFERA

double row of pores, or, in the " dendritine " varieties, of an
opening the margins of which are produced into branched and
winding recesses.

The extent of the septum which forms the terminal face of
each chamber, and is perforated by the apertures, varies, of course,
with the shape of the chambers, being small and more or less
circular in outline in the crozier-shaped forms, and much elongated

ffiT

FIG. 29.

Peneroplis pertusus, Forsk. vl, a common
flattened variety ; fl2, the crozier-shaped variety
(x 2(5). A, central part of section of megalo-
spheric form. B, of the microspheric form ;
sp.p, spiral passage ( x 280).

in the flattened forms. In the latter case it is markedly convex
when seen from the side.

In the megalospheric form the size of the oval megalosphere
varies in samples from different localities. Thus, in 300 specimens
from Aripo, on the coast of Ceylon, I find the average value of
M to be 30 p, and it varies in different individuals from 24-42 p.
In a batch from Watson's Bay, Port Jackson, the average value is
42 p., and the individual variation ranges from 32-59 /z. In two
specimens in a West Indian gathering, however, M= 19 and 22 /A.

A narrow spiral passage leads from the megalosphere and

THE FORAMIN1FERA 95

winds round half to three-quarters of its circumference before
opening into the first of the spiral series of chambers. As
Rhumbler has shown (35) the walls of the central chamber and
the beginning of the spiral passage are traversed by minute radial
perforations, so that the test formed in the earliest stage of the life
of this form of Peneroplis is perforated, though the walls formed
subsequently are, at any rate usually, imperforate, in accordance
with the rule in the Miliolidea.1

The microspheric form of Peneroplis is very scarce in the
material which I have examined. Among 1000 specimens I have
met with only five. Its proportion to the megalospheric form
appears, however, to vary in different localities. Thus, in a
sample of sand from the Maldive Islands, dredged in 47 fathoms
by Mr. J. S. Gardiner, the proportion is 3 to 108, or 1 to 36,
which is about the same as obtains in Polystomella. On the other
hand, in a batch of 480 specimens from Watson's Bay, I failed to
meet with a single microspheric form. The values of m in my
specimens are 17, 18, 19, 22, and 24 p.. On comparing these with
the values of M, it will be seen that the megalosphere may, in
some cases, fall below the microsphere in size. The two forms
are, however, sharply separated by the fact that, as in Orbiculina
and Orbitolites, the spiral passage is absent in the microspheric form
(Fig. 29).

Orbiculimi. — All the forms of the genus are included in a single
species, 0. adunca (F. and M.). Its distinctive features are the
subdivision of the chambers into chamberlets, and the equitant
character of the chambers in the earlier convolutions, giving rise
to a prominent umbo at the centre of the flattened test. It
affords a good example of the mode of occurrence of variation
in one of the Foraminifera with a definitely symmetrical test.

Although the tests present themselves under a great diversity
of external shape, the variations from the normal are limited to
certain well-marked and definite lines. Fig. 30 shows the main
varieties, as they are represented in a sample of ballast sand from
the West Indies, kindly sent to me by Mr. F. W. Millett.

The youngest tests are uniformly nautiloid (Fig. 30, a and b),
the chambers succeeding one another in a closely wound spiral.
As the sections represented in Fig. 31 show, the chambers are
elongated transversely to the course of the spiral ; hence we may

1 The tests of Peneroplis present throughout their growth a surface pitting, which
is usually shallow, but may be so deep as to amount very nearly to perforation.
Indeed I am not convinced that some forms are not completely perforated in the
later as well as in the initial chambers. As we shall see below, the central chamber
and spiral passage of the megalospheric form are perforated also in Orbiculina and
Orbitolites marginalis. There appears therefore to be no justification for the separa-
tion of Peneroplis from the other genera of this family, as proposed by Rhumbler,
on account of its supposed peculiarity in this respect.

96

THE FORAMINIFERA

speak of their two ends as inner and outer — the former directed
towards the concave side of the spire, the latter towards the
convex side. While they are simple at their outer ends, the

Tests of Orbic-ulina adunca,
F. and M. a-b, young speci-
mens ; c-e, var. flabelUformis ;
f and (/, var. compressa; h,
var. adunca; B, full-grown
specimen of the inicrospheric
form of adunca. (g and B are
magnified about 8 times, the
other tests about 7 times.)

chambers of young specimens of all varieties are equitant at their
inner ends, being produced on either side over the surface of the
already formed test, in alar prolongations (cp. Fig. 32).

As growth proceeds, the chambers become more and more

THE FORAMINIFERA 97

elongated, and the characters of the three main varieties become
apparent, the shape ultimately assumed depending on the extent
to which the successive chambers overlap their predecessors at
either end.

In one variety, which may be called flabelliformis l (Fig. 30, d
and e), the mode of growth changes from the spiral to the recti-
linear. After the nautiloid stage the chambers lose their equitant
character, and a series of long chambers is formed, each of which
slightly exceeds its predecessor at either end. The fan-shaped
tests here figured are thus produced.2 They attain 2 mm. in their
greatest diameter.

The commonest variety may be called variety adunca proper
(Fig. 30, h). It includes the forms 0. adunca and 0. orbiculus (F.
and M. spp.), of which the latter is the young stage of the former.
Here the spiral mode of growth and the equitant character of the
inner ends of the chambers are maintained until the test is complete.
At their outer ends the chambers extend little, if at all, beyond
the outer ends of their predecessors, and thus build up the abrupt
prominence in the outline of the test, characteristic of this variety.

The third main variety is compressa (the 0. compressa of d'Orbigny ).
In it the chambers cease to be equitant, and increase rapidly in
length at both ends, being applied to and encircling more and
more of the margin of the previously formed test. It thus comes
about that the two ends of the chambers meet, forming a complete
annulus. Henceforth the mode of growth is continued on the
annular plan, and the disc-shaped tests represented in Fig. 30, g,
are produced. In the sample examined the great majority of the
specimens of Orbiculina are of the variety adunca. The next
commonest variety is compressa, while flabelliformis is compara-
tively scarce.

This sample consisted in large part of the tests, young and
old, of Orbiculina, and in hunting through it a form which did not
fall into one or other of these varieties in some stage of growth,
was very rare, the few exceptions being of an intermediate
character.

The condition of the central chambers of Orbiculina can only
be observed in sections.

Certain large forms of the variety adunca (Fig. 30, B), attaining
a diameter of 6 mm., and distinguished also by the greater thickness
of the tests and the much extended alar prolongations of the

1 In the description of Brady's figures of Orbiculina the term flabelliform is
applied to two varieties — one (Fig. 7) the var. adunca; the other (Fig. 8) an
exceptional form intermediate between varieties adunca and cvmpressa. The term
naturally, however, implies a bilaterally symmetrical test, and I have therefore used
it as stated above.

2 The cornucopia -shaped test, represented in Plate XIV. Fig. 4 of Brady's
" Challenger " Restart, is a rare form of this variety in which the increase is still less.

7

THE FORAMINIFERA

chambers, are shown by section to be microspheric, though in their
younger stages the microspheric forms are not readily distinguished
by external characters. In a set of 38 examples of this variety,
of such a size that the microspheric forms were not externally
differentiated, 34 were found, by section, to be megalospheric and
4 microspheric, a proportion of 1 to 9'5. The diameter attained by
the megalospheric form of this variety is, in my examples, 4 mm.

B

^^•B**""

FIG. 31.

Central regions of sections of Orl/iculina culunca in the median plane. A, large, A', small
•example of the megalospheric form. B, microspheric form, x 93. b, centre of B, x 250. sp.p,
spiral passage.

I have failed to find a single microspheric form of the variety
compressa ; 1 00 examples, examined in section, belong to the
megalospheric form. Among 24 examples of the variety flabelli-
formis, however, one appears to be microspheric.

The diameters of the megalospheres in well -grown specimens
of the varieties adunca and compressa are as follows : —

Var. adunca .
,, compressa

No. of Specimens
examined.

28
32

Highest
Value of M.

146 /J.
155 M

Lowest
Value of M.

81 /J.
70 /x

Average.

117 M
109 M

THE FORAMINIFERA 99

In flabelliformis the value of M is less, though the average in
my specimens is not below 64 p.

In the microspheric form the average value of m in six cases is
18 /*, the highest being 21 p, and the lowest 16 p.

In the megalospheric form the megalosphere is followed by a
spiral passage reaching round |-f of its circumference, and both
megalosphere and spiral
passage frequently ex-

hibit the perforated con- ,.-.....

dition found in Peneroplis ...-•??' Vo£~s ' ^**h"ti__

(Figs. 31, A, and 32). ,,< o ^

The first of the spiral , : \;

series of chambers is S^HB '•.vja-'P^'

usually simple, but it L-^^'

frequently opens into its
successor by two aper-
tures, and in the second Flo 3.,

the transverse ribs gener- OrUculina adunca, central part of a section of a

ilhr maVo tViair armo-ar megalospheric test passing transverse to the median
appear- p,a*e jr megalosphere ; sp.c, spiral passage.

ance, which, becoming

more marked in the following chambers, subdivide them into
chamberlets. The chambers also communicate with one another
by an increasing number of apertures, arranged in several rows
along their peripheral walls.

In the microspheric form of Orbiculina, as in that of Peneroplis,
the microsphere opens direct into the first of the spiral series of
chambers, and in this form there are generally some twenty simple
chambers communicating by a single aperture before the sub-
division into chamberlets begins (Fig. 31, B and b).

Such are the characters of well-grown specimens of Orbiculina;
but on examining the construction of the tests of small specimens,
as displayed in section, a mode of variation of a different kind
becomes apparent, one which illustrates the phenomenon of Initial
Polymorphism described by Munier-Chalmas and Schlumberger
in Idaliiia. In the sample of sand which furnished the varieties
above described were numbers of small megalospheric specimens
resembling the young of the typical forms (c and / in Fig. 30),
but beginning in a megalosphere of small size. In the specimen
represented in Fig. 31, A', the central part of one of these is seen
in section. Here the megalosphere measures only 34 p. in diameter.
Associated with the small size of the megalosphere of these forms
is a long series of single chambers before the subdivision into
chamberlets begins. In both characters they thus vary in the
direction of the microspheric form, though always distinguishable
from it by the presence of the spiral passage. In Orbiculina then,
as in Idaliiia, the construction of the early part of the test is

THE FORAMINIFERA

correlated with the size of the megalosphere. If it is small the
arrangement approaches that of the microspheric form, if large it
departs more widely from it.

Another feature met with in some of these stunted forms,
though by no means in all, is that the subdivision into chamber-
lets may be incomplete or wholly absent. Sometimes the sub-
division dies out in the terminal chambers after becoming estab-
lished in their predecessors ; in others it is absent throughout the
test. I am inclined to regard these latter forms as examples of
Orbiculina which have lost their secondary septation by "degenera-
tion " rather than as representatives of Peneroplis, because of the
existence of the intermediate forms just alluded to, in which the
subdivision dies out in the terminal chambers, and also because
they agree so closely in external features with small examples of
" typical " Orbiculina, that they cannot be distinguished from them
by the external characters of the tests.1

Four well-marked species are generally included in the genus
Orbitolites, of which three — 0. marginalis, duplex, and complanata —
are intimately related to one another, and form a remarkably
complete series of grades of development, while 0. tenuissima
stands apart. The three former are inhabitants of the littoral
zone of tropical and subtropical seas, while the last lives in the
deeper parts (250-1700 fathoms) of the North Atlantic, from
which it extends into the Mediterranean.

In all the annular arrangement of the chambers is assumed
early in life, the tests have a flattened discoidal shape, and an
umbo is absent, as the chambers are not equitant at any stage of
growth. All but the earliest chambers are subdivided into
chamberlets.

In 0. marginalis (Lamk.) the chamberlets are generally some-
what quadrangular when seen on the face of the disc, and the
chambers they compose have an evenly curved outline. The
disc consists of a single layer of chambers, and they are throughout
simply applied to the peripheral margins of their predecessors.
The radial septa which divide the adjacent chamberlets of an
annulus from one another are traversed at their peripheral
border by a canal, which places the chamberlets in communication
with one another, and the canals of any one annulus may thus be
regarded (following Carpenter's nomenclature) as composing an
annular canal. From the canal, as it traverses a septum, a passage
leads in a radial direction and opens either to the exterior by a

1 I have not had the opportunity of examining examples of Archiacina, but from
the figure given by Schlumberger (50, Plate III. Fig. 2) it seems possible that this
may be a form of variety compressa which has similarly lost the subdivision of its
chambers.

THE FORAMINIFERA

101

pore at the margin of the disc, or into a chamber of the suc-
ceeding annulus, as the case may be. In this species the canals
all lie in one plane, which is the median plane of the disc (cp.
Fig. 38, «i).

n

m

FIG. 33.

OrbitdUes niarginalis, Lauik. m, whole test ( x 20) ; A, centre of megalospheric, B, of micro- '
spheric form, x 100 ; b, centre of latter, x 280 ; x, the outer end of the last series of cham-
berlets which follows the spiral mode of growth. The figures 3 and 11 in A and 6 mark the
last of the undivided chambers in the two forms respectively.

The microspheric form (Fig. 33, B and b). — The microsphere
opens directly, without the interposition of a spiral passage (as
appears always to be the case in the Peneroplididae), into the
first chamber. The chambers are arranged at first in a gradually
expanding spiral, eleven to sixteen simple chambers succeeding
one another as in the genus Peneroplis, but communicating by

102 THE FORAMINIFERA

single apertures. As the spirat increases in width the chambers
become divided into chamberlets, and the number of apertures is
correspondingly increased, the arrangement at this stage repeating
that which in the earlier stages of growth is common to all
varieties of Orbiculina,, except that there are no alar prolonga-
tions. When the stage of the spiral
mode of growth is complete, the
chambers become successively more
and more embracing and the annular
arrangement is attained.

In the megalospheric form (Figs.
33, A, and 34) the megalosphere is
pear-shaped. A spiral passage leads
from it, and extends round about
three-quarters of the circumference
of the megalosphere. As in the case
of Peneroplis and Orbiculina the walls
of the megalosphere and the spiral
Fl°- 34- passage may be perforated (Fig. 34).

Central chambers of 0. riiarginalis. mi. i i- i- i_-Yj>n

showing the perforated wall of the J-he single chambers which follow
megalosphere. are usuaiiy on]y three or four in

number, and beyond, the chambers become subdivided, and the
arrangement resembles that of the microspheric form.

The dimensions of the central chambers in the specimens
which I have examined are as follows. It will be seen that as in
Peneroplis those of the megalosphere vary in the samples from
different localities.

No. of Highest Lowest Average

Specimens Value of Value of Value of

examined. M or m. M or m. M or m.
Megalospheric — •

from Aripo (Ceylon) . 43 53 M 24 M 36 ^

„ W. Indies . 47 78 /* 37 p 51 A*
Microspheric —

from Aripo . 17 19 /t 15 n 17 /t

,, W. Indies . 1 ... ... 18 M

In Orbitolites duplex, Carpenter, the arrangement is at first
sight similar, but the chamberlets are more elongated in a direc-
tion perpendicular to the face of the disc. Here, again, they are
in communication by a single annular canal, but the apertures
which open out of it and lead to the chamberlets of the succeeding
annulus are disposed obliquely and lie in two planes, one on
either side of the median plane (cp. Fig. 38, d). There are thus
in typical specimens two rows of pores at the margin of the
disc. There is, moreover, a difference in the shape and arrange-
ment of the chamberlets. Instead of the regularly curved series
of quadrangular chamberlets which make up the well-marked
annuli of 0. marginalis, the chambers (especially those near the

THE FORAMINIFERA

103

centre of the test) are oval, being elongated in a tangential
direction, and fall into lines like those on the back of a watch,
making what is known as the "engine turned" pattern.

Orbitolites duplex, Carpenter, in, whole
test of inegalospheric form, x 5 ; A A' A",
central parts of three varieties of the
inegalospheric form ; B, of niicrospheric .
form, x 100 ; b, centre of latter, x 280.

In an example of the microspheric form the microsphere is 20 //,
in diameter, and here again the spiral canal is absent (Fig. 35, B
and b). There are eleven single chambers before the subdivision
into chamberlets begins, and then the orbiculine arrangement is
assumed, to pass in turn into the annular, as in 0. marginalis.

In the inegalospheric form the megalosphere is round or pear-
shaped, and has an average mean diameter of about 76 p. (the

104

THE FORAMINIFERA

diameters in 108 specimens vary between 49 and 110 /A). The
spiral passage almost encircles the megalosphere, and is wider than
in 0. marginalis. Though it sometimes communicates with only a
single chamber (Fig. 35, A"), there are usually two to five chamber-
lets into which it opens directly, by as many apertures (Fig. 35,
A and A'), so that the peneropline and orbiculine stages are in such
cases abridged, and the annular arrangement speedily attained.

In a sample of the tests of 0. duplex from Aripo, all (108 in
number) were megalospheric. The specimen of the microspheric
form above described is from Funafuti in the Pacific.

PIG. 36.

Orbitolites complanata, Lamk. The megalospheric (A, «) and microspheric (B, V) forms,
whole, and in section, x 5. The primitive disc is seen at the centre of A and a, and young
megalospheric individuals (= primitive discs) may be seen at the left-hand end of 6.

In Orbitolites complanata, Lamk. (cp. p. 73), a much greater degree
of complexity is attained, in that the chambers, which in 0. duplex
are elongated in a vertical direction, are differentiated into three
several layers — two layers of superficial chamberlets, one on either
face of the test, and an intermediate layer of columnar spaces lying
between them (Figs. 36, b, and 38, c). There are here two
annular canals corresponding to each annulus of chamberlets,
lying at either end of the columnar spaces in the two strata of
the test between these and the superficial chamberlets. There
are abundant communications between the chamberlets, and those

THE FORAMINIFERA

105

at the periphery open to the exterior by vertical rows of pores
at the margin of the disc.1

The Microspheric Form. — The centre of the disc of this form
is much thinner than that of the megalospheric (Fig. 36, a and b).
It is often the seat of secondary growth which occurs towards the
end of the vegetative phase, giving rise to a button -like ex-
crescence and accompanied by absorption of the original central

FIG. 37.

Orbitolites complaiuitu, Lamk. Central
regions of sections of the megalospheric
(A) and microspheric (B) forms, in the
median plane of the discs, x 100. ca.ch,
circumambient chamber ; Af, megalo-
sphere ; p, partition ; sp.p, spiral passage ;
11, the last undivided chamber of the
microspheric form.

chambers. If this has not occurred an arrangement similar to that
of the central regions of the microspheric forms of marginalis and
duplex is revealed by section. In two specimens I find that the
microsphere has a mean diameter of 17 and 18 p., a spiral
passage is absent, and seven to eleven single chambers succeed
the microsphere. These are followed by subdivided chambers,
continuing the spiral, and the mode of growth then changes to
the cyclical as in the other species (Fig. 37, B).

In some varieties, at least, of this species the microspheric form
attains a much larger size than the megalospheric (Fig. 36, A
and B), and the large forms with double and contorted margins,
described as variety ladniata, Brady, are all, as far as my experience
goes, microspheric. It seems, indeed, that the peculiarity of the
margin of this form may be regarded as a provision for supplying
a larger number of peripheral brood chambers for the accommoda-
tion of the megalospheric young into which the protoplasm
becomes divided.

For the details of the structure, cp. Carpenter's descriptions (8 and 9).

106 THE FORAMINIFERA

The megalospheric form begins in a structure called by Carpenter
the primitive disc (Figs. 36, 37, A, and 38). It consists of (1)
the megalosphere, which is pear-shaped (about 107 p. in mean
diameter) ; (2) a spiral passage leading from the megalosphere,
and opening into (3) a large crescent-shaped chamber, one horn
of which extends round one side of the megalosphere, and the
other along the outer side of the spiral passage. It results from
this arrangement that the outer wall of the latter forms a parti-
tion (p) disposed perpendicularly to the flattened surface of the
primitive disc, and separating the spiral passage from the crescentic
chamber. The partition ends in a free border. The spiral passage

-r

Fro.

Diagram representing the transition from the simple ("marginalis') to the complex
(" complanata ") type of structure in the growth of a sub-typical individual of Orbitolites com-
planata. The primitive disc and half the test of a megalospheric form are represented in
section. The letters P D are placed beneath the centre of the primitive disc, m, part of test
formed on the marginalis type ; d, that formed on the duplex type ; /, that formed on the
type of a fossil form of 0. complanata ; c, that of the typical 0. complanata ; ac, annular canals ;
cs, columnar spaces ; mp, marginal pores ; r, radial canals ; sc, superficial chamberlets. (After
Carpenter, but modified.)

with the crescentic chamber together compose the circumambient
chamber of Carpenter. The whole of the peripheral wall of the
circumambient chamber is perforated by pores opening into the
innermost chamberlets, which are thus disposed in a complete
annulus from the beginning. In some primitive discs there is a
single row of pores at the margin, in others there are two or
three rows. In the latter case the three-layered arrangement of
chamberlets characteristic of 0. complanata is assumed directly ;
while in the former the region of the test immediately surround-
ing the primitive disc may present varying degrees of development.
In some (Fig. 38) the rings of chamberlets are at first in single
series, arranged on the marginalis type, and they are succeeded by
annuli on the duplex type, the three -layered character being
ultimately assumed. In others the arrangement begins on the
duplex type. Here, again, we have examples of initial polymorphism.
On comparing the primitive disc of 0. complanata with the
centre of the tests of the megalospheric forms of the other species,
it appears that the crescent-shaped chamber of complanata may be

THE FORAMIN1FERA 107

regarded as an expansion of the end of the spiral passage. In
those forms of duplex in which the spiral passage communicates
with more than one chamberlet the end is somewhat expanded.
An extension of this expansion round the outer side of the spiral
passage would give rise to the complete crescentic chamber which
we find in complanata.1

Looking back on the series of forms of Peneroplididae hitherto
examined, a gradual increase in complexity of structure is to be
observed. We pass from Peneroplis, with undivided chambers dis-
posed at first on a spiral and often, later, on a rectilinear plan, to
Orbiculina, with subdivided chambers similarly disposed, though in
one variety of the megalospheric form the annular arrangement
is assumed. In OrUtolites marginalis the chambers and pores are
disposed in a single plane, and in the early stages of growth we
find arrangements repeating in some of their features those of
Peneroplis and Orbiculina before the annular arrangement which is
characteristic of OrUtolites is arrived at. 0. duplex, with its double
series of pores, furnishes an intermediate stage to the complex
three-layered condition of 0. complanata.

In his Report on the genus Orbitolites, Carpenter made this
series of genera and species the subject of a " Study of the Theory
of Descent," and laid stress on the remarkable manner in which
the forms of the simpler members are repeated in the life-history
of the more complex. When this Report was published (1883)
attention had only recently been drawn to the phenomenon of
dimorphism in the Foraminifera, and Carpenter does not appear
to have been aware of the existence of the microspheric forms, as
constituting a distinct set of individuals.

On comparing the mode of growth of the microspheric and
megalospheric forms, we find a contrast between them comparable
to that presented by the Miliolinidae. While the microspheric
forms repeat successively the shapes and arrangements of chambers
which are permanent in other, and in this case, simpler, members
of the group, in the megalospheric forms these stages are to a
greater or less extent abridged or altogether omitted. Thus in
the megalospheric form of Orbitolites marginalis the peneropline
series of single chambers which succeeds the spiral canal is fewer
in number than in the microspheric form, but the orbiculine
arrangement is well represented. In this form of 0. duplex the
peneropline condition has almost or entirely disappeared, and the
orbiculine stage is much abbreviated. In 0. complanata both

1 The remarkable fossil form Meandropshia described by Schlumberger (59)
appears to be related to Orbitolites, the surface of the disc being covered with a
layer of chamberlets arranged in a Meandrina-like manner. Schlumberger finds both
microspheric and megalospheric forms are represented in his specimens.

io8 THE FORAMINIFERA

peneropline and orbiculine arrangements have entirely gone in
the megalospheric form.

We turn now to the other species, commonly included in the
genus Orbitolites, the 0. tenuissima of Carpenter (Figs. 39 and 40).

The tests are exceedingly thin (-^-5-5- inch), though they may
attain 30 mm. in diameter.

FIG. 39.
Orlitolites tenuissima, Carp. The complete test, x about 11, from a photograph.

There are undoubtedly points of similarity in structure be-
tween this species and 0. marginalis, the simplest of the other
members of the genus. The annular arrangement succeeds a
spiral one, and the annuli are divided into chamberlets by septa
disposed in a manner which is very similar to that found in 0.
marginalis, especially in examples from deep water in which the
radial septa are sometimes incompletely developed. Coming to
the middle of the test, however, we find ourselves in new country.
In five specimens a globular central chamber about 31 /z in
diameter * occupies the centre, and leading from this is a succession

1 In that figured in Plate I. Fig. 1 of Carpenter's Report the central part of the
test appears to have been left blank, without any intention of depicting a central
chamber of the size of the blank space. The specimen here figured was obtained by
the Travailleur in the Bay of Biscay, and I am indebted to the authorities of the
British Museum for the opportunity of giving a photograph of it. The central
chamber measures 30 x 31 p.. In the four other specimens in which I have been able
to obtain evidence of the size of the central chamber, it appears to be about the
same.

THE FORAMINIFERA

109

of narrow elongated chambers, wound in a planospiral manner
about the central chamber in some 7-8 convolutions. The lengths
of the several chambers vary from 2£ convolutions to \ of a con-
volution of the spiral. The arrangement and mode of communi-
cation of the chambers recalls the irregular spiroloculine tests of

/ ;

FIG. 40.

Orbitolites tenuissima, Carp. Central region of the specimen represented in Fig. 39.
The figure 8 is in the eighth and last convolution of the inner series of chambers.

X 80.

Ophthalmidium (Fig. 41). As the five specimens have an approxi-
mately similar arrangement, it is probable that the form we are
dealing with is megalospheric, though the size of the megalosphere
is small.

When comparing the central regions of 0. marginalis (megalo-
spheric) with those of 0. tenuissima, Carpenter regarded the spiral
passage of the former as representing " the whole of the original
'spiroloculine' coil, drawn up into itself" (p. 24). The difficulty,
however, of recognising the long spiroloculine (or Ophthalmidium-
like) coil of tenuissima in any of the modifications of the spiral
passage met with in the other species of the genus Orbitolites is so

110

THE FORAMINIFERA

great that we are led to doubt whether tenuissima is really allied
to them. On the other hand, the resem-
blance of the inner chambers of tenuissima to
Ophthalmidium,a,mGmber of the Hauerinidae,
suggests that it may be derived from this
family, and have acquired the cyclical mode
of growth independently. The acceptance
of this view is perhaps rendered easier by
the existence of another group, the Oper-
culino-Cydodypeus series, in the higher mem-
bers of which the annular mode of growth
is likewise attained (see p. 128). It seems
at any rate worth while to entertain the
possibility of this explanation, before ac-

. J , . ,

cepting a conclusion so damaging to a body

of evidence which may be found, if duly considered, to furnish

the clue to many complicated problems of relationship.1

FIG. 41.

Ophthalmidium tumiduluin,
ady. "Challenger" Report,
. XII. Fig. 6.

Family Alveolinidae. — The genus Alveolina which represents
this family contains a number of recent and fossil forms which
appear to branch off from the Miliolid stock in the neighbourhood

Tests of (a) Alveolina boscii, Def., x about 17 ; and (b)
A. melo, F. and M., x about 22.

of the genus OrUculina. They are char-
acterised by elongation of the chambers
in a plane at right angles to that in
which they are developed to form the
disc -shaped tests of Orbitolites — that is,

in the direction of the axis of the spire. The result is the
formation of a series of oblate, spherical, ovoid (Fig. 42, b), fusiform,
and cylindrical (Fig. 42, a) tests, each chamber extending beyond
its predecessors laterally to a greater or less extent, and thus
increasing the axial length of the test. The chambers are short
in the direction of the plane of the spire, and subdivided into
chamberlets by vertical septa lying parallel with that plane. In

1 It would perhaps be premature, while we are not yet acquainted with the two
forms of tenuissima, to alter its systematic position, but should this view of its re-
lationship be confirmed, it must be separated as a distinct genus to which the name
Cydqphthalmidinm might be given.

the recent Alveolina boscii the chambers are further subdivided by
horizontal septa.

Schlumberger states (51) that Munier-Chalmas has recognised
the phenomenon of dimorphism in a fossil Alveolina, of which the
microspheric form is distinguished by a very small central chamber
surrounded by five simple chambers, which are not subdivided.
It would appear, therefore, that a peneropline stage is represented
also in the development of the microspheric form of this genus.
In specimens of the megalospheric form of A. boscii I find the
central chamber to be ovoid and to measure about 150 p. in long
diameter.

Life-histories and nuclear characters of the Miliolidea.

Direct observations on this head are very scanty.

In Cornuspira, as we have seen (p. 74), the megalospheric
form may give rise to megalospheric young, and the same event
has occurred in a specimen of a Milioline form (1 Quinqueloculina) in
my possession. In this case the megalosphere of the parent was
only 30 //, in diameter, and those of the young varied from 20 to
43 fji. Schlumberger (49) and Schaudinn (42) have also described
the production of broods of young, which were evidently megalo-
spheric, in the Miliolinidae (the latter author in Quinqueloculina
seminulum, L.), but the nature of the parent is not indicated. In
these Miliolinidae it appears that the division of the protoplasm to
form the young may occur within the parent test or outside it.

The production of megalospheric young by the breaking up,
within the test, of the protoplasm of a megalospheric parent, had
occurred in a specimen of Peneroplis described by Schacko (39) ;
and in this case the young, consisting of the central chamber and
spiral passage, resemble in size and shape the corresponding parts
of the parent. Biitschli (7) has found a single nucleus in two
specimens of Peneroplis, and 18-20 in another. In all three cases
the parents were megalospheric, and in the last we may suppose
that the division of the nucleus had occurred preparatory appar-
ently to the production of a brood of megalospheric young, as in
the cases of Discorlina and Patellina (see p. 123).

Of the genus Orbitolites our knowledge is somewhat fuller.

I have a specimen of the megalospheric form of 0. marginalis
in which the two or three peripheral annuli contain young, con-
sisting of the megalosphere and spiral passage. The chambers
containing them are in this case not different from the ordinary
marginal chambers.

A specimen described by Semper (63) appears to have belonged
to 0. duplex, and this also is a megalospheric parent with megalo-
spheric young. He mentions that the chambers containing them

112 THE FORAMIN1FERA

were "ziemlich viel grosser" than those internal to them, and
thus it may be the case that in this as in other characters 0. duplex
is intermediate between marginalis and complanata.

In 0. complanata the microspheric forms known as var. laciniata
produce megalospheric young. The double convoluted margins
of this variety are not completely subdivided into chamberlets as
are the more central regions of the disc, but, in part at least, con-
tain spacious chambers extending through the thickness of the
disc, and round a large part of the periphery. Into these (as well
as into similar large chambers in the secondary growths formed on
the surface of the disc) the protoplasm withdraws, at the reproduc-
tive phase, from the whole central region of the original test, and
becomes divided up into young megalospheric forms, which are
liberated by the breaking down of the limiting walls. This mode
of reproduction in 0. complanata was first described by Brady (4),
though he was not aware of the full significance of his observation,
and afterwards by myself (20). In Fig. 36, b, a form with a simple
margin is seen bearing megalospheric young.

The megalospheric form of 0. complanata may also, as we have
seen (p. 74), give rise to a brood of young of the same nature,
but there can be no doubt that a phase recurs in the cycle of the
life-history in which, as in Polystomella, zoospores are produced.

The microspheric form of 0. complanata has, scattered through
its protoplasm, large numbers of rounded nuclei, which may fre-
quently be found constricted as though in process of simple
division. In the megalospheric form a large nucleus may often be
found throughout the greater part of the life lying in the primitive
disc, and thus, as already pointed out (p. 71), at the central part
of the protoplasm (20).

Calcituba polymorpha appears to be a degenerate member of the
Miliolid stock. Its life-history, as exhibited in aquaria, has been
investigated by Schaudinn (46). It forms wide adherent expan-
sions on the surface of foliaceous algae on which it feeds, spreading
in irregular annular patches — like fairy rings. The colony may
begin as a spherical central chamber with a spiral passage leading
from it — the form which occurs so frequently at the centre of the
megalospheric tests of the compact Miliolidea. From such a centre
branching offsets extend in a radial direction over the algal sub-
stratum, and as this is disintegrated by the organism feeding on
it, the central regions, left unsupported, may fall away, while the
margins spread in the annular fashion described. The portions
which so fall may start a similar colony forthwith, or their proto-
plasm may break up into small portions (1-20) of varying size,
which at first crawl about as naked masses, and later, on initiating
a new colony, may secrete the Miliolid form of test mentioned
above.

THE FORAM1NIFERA

The walls are chitinous tubes with a calcareous deposit. They
are imperfectly divided into chambers, and are not perforated. A
flagellate stage did not come under observation. The protoplasm
contains large numbers of small nuclei.

ORDER Textularidea.

This order contains a number of genera which are excellent
examples of the multiform (biformed and triformed) condition of
the test.

The arrangement which has been regarded as typical of the genus
Textularia is one with two rows of alternating chambers, but Schubert
has recently drawn attention to the fact (65) that many, if not
all the forms included in it, are biformed, some having the earlier

FIG. 43.

Spiroplecta (Textularia) sagittula, Def. A, the megalospheric, B, the microspheric form,
X 55 ; b, the earlier chambers of the latter, x 150. A and B represent specimens stained, and
mounted in Canada Balsam, and show the nuclei.

chambers arranged in a planospiral, others in a rotaloid, and others
again in a triserial manner, before the characteristic biserial arrange-
ment is assumed. Thus "Textularia" sagittula, Def., begins as Schubert
states, and as I have also had occasion to observe, in a planospiral
series of chambers, the arrangement being, in fact, that character-
istic of the genus Spiroplecta. Out of a batch of 63 specimens of
this species collected at Plymouth in the month of July, I found 57
to be megalospheric, and 6 microspheric, a proportion of 9 to 1.

8

114

THE FORAMINIFERA

In the microspheric form (Fig. 43, B and b) m= 15-18 /^, and is
followed by some five or six chambers arranged in a spiral before
the alternating arrangement is assumed. One specimen contains
at least 13 nuclei.

In the megalospheric form (Fig. 43, A), the average mean dia-
meter of the megalosphere is about 60 /* (the limits of those
measured were 44 and 72 /z). The initial spiral is here somewhat
shorter, consisting of four chambers. A single large nucleus is
seen in these specimens some distance along the alternating set of
chambers.

The spiral arrangement of the early chambers is much more
conspicuous in Spiropleda annectens, P. and J. (Fig. 44, A, B, and b).

Fio. 44.

A, B, and b, Spiroplecta annectens, P. and J ; A, the megalospheric, B, b, the microspheric
form. C, Verneuilina pygmaea, Egger. D, Bigerterina robusta, Brady. E, Clavulina angularis,
d'Orb. A and b, x 70, original ; B-E, from Brady (3).

What appears to be the megalospheric form of this species has
long been known as a Cretaceous fossil. The species occurs at the
present day round the coasts of Australia, and has been recognised
in sand from the Malay Archipelago by Mr. F. W. Millett (24,
Part VII., 1900), to whom I am indebted for calling my attention
to the evidence of dimorphism in this species, and for the oppor-
tunity of examining the specimens from which the following details
are given.

Among six specimens of the megalospheric form (Fig. 44, A), the
average value of M = 60 yu, (the limits of variation are 53 and 71 /*),
and one nearly complete spiral whorl of chambers intervenes before
the straight and biserial part of the test begins.

The microspheric form attains a larger size. Among 15 speci-
mens, the average value of m= 17 p (the limits being 11 and 20 //,),

THE FORAMINIFERA

and 2|-3f whorls of chambers arranged in a spiral form the
earlier part of the test. The later, straight part is much longer
than in the megalospheric form, and in both forms the biserial
arrangement may give place to a uniserial one at the end.

The characters of other genera of this family are indicated in
the table of classification, and some of them are represented in
Fig. 44, C-E, and Fig. 54.

ORDER Chilostomellidea.
I am not aware of any record of dimorphism in this order.

ORDER Lagenidea.

Schlumberger has found representatives of both generations
in Nodosaria (Dentalina) guttifera and Nodosaria hispida, the megalo-
spheric forms beginning in a large initial chamber (Fig. 45, A),
larger than that which succeeds it, and having only five or six

Flo. 45.

Megalospheric forms of— A, Nodosaria hispida, d'Orb. B, Nodosaria (Dentalina) communis,
d'Orb. C, Frondicularia alata, d'Orb. (After Brady, 3.)

chambers in all ; the microspheric having a larger number of
chambers, and tapering gradually to a fine point at which the
little microsphere is situated. In such tests the phenomenon of
dimorphism is presented in the simplest possible form.

Fornasini (15) has shown that Frondicularia (Fig. 45, C) is
dimorphic.

The monothalamous Lagenidae often present a great resem-
blance to the single chambers of Nodosaria, but the nature of the
relation between the two groups is obscure. Neumayr derives the
former from the latter by degeneration ; Rhumbler, by the falling

THE FORAMINIFERA

apart of the chambers. A remarkable feature of some Lagenidae is
the " entosolenian " condition in which the tubular neck is, as it
were, inverted into the interior of the test (Fig. 46, b). A similar

FIG. 46.

a, Lagena sulcata, W. and .1. , x 60. b,
L. globosa, Montagu, showing the ento-
solenian neck. (After Brady.) x 80.

FIG. 4

Cristettaria crepidida, F. and M., after
Brady (3, PI. 68, Fig. 1), showing the pro-
duction of a brood of megalospheric young,
of varying size, by a megalospheric parent.
X 38.

inverted neck is found in Cymbalopora, and occasionally in Poly-
morphina (3, pp. 558 and 638).

The observations of Burrows and Holland (5) on Cristel-
laria gibba, and C. platypleura appear to show (though no
measurements are given) that the authors have found dimorphic
forms of Cristellaria. In C. cenomana, Schacko ^(40) describes a
form which, he suggests, is micro-
spheric, having a central chamber
measuring 40 ^ while M = 75 /z.
In the specimen of C. crepidula
shown in Fig. 47, however, the
size of the young chambers (which
we may suppose to be megalo-
spheres) varies much, and the
smallest appear to measure about
40 p in diameter; and as this
measurement is rather large for
the size of a microsphere, the mi-
crospheric character of Schacko's
specimen is, at least, open to
doubt.

The genus PolymorpMna is FIG. 4s.

remarkable for the fistulose PolymorpMna compressa, d'Orb. ; c, the
, . i_ • i simple form, x 32 ; d, the fistulose form,

branching processes whicn are x ss. (After Brady.)

developed in the later stages of

the growth of the test. What relations these may have to the

life-history has not been determined (Fig. 48, c and d).

THE FORAMINIFERA

117

Schlumberger has shown (50) that in Siphogenerina glalra
the microspheric form tapers to a point at the initial end, and has
9-10 chambers arranged alternately before the uniserial mode of
growth is assumed ; while the megalospheric form is short, begins
abruptly with a large central chamber, and has only three alternat-
ing chambers prior to the uniserial chambers.

ORDER Globigerinidea.

In this group, as defined by Brady, the tests consist of a few
inflated chambers arranged in a spiral manner. The members of
it inhabit the surface waters of the ocean, furnishing an important

FIG. 49

Gldbigerina bulloides, d'Orb. (to left), and Orbulina universa, d'Orb. (to right). (From
Rliumbler, 38.) The figure of G. bulloides represents the test as seen from the superior sur-
face. The specimen departs from the normal in possessing an aperture on this aspect of the
terminal chamber.

constituent of the pelagic fauna ; and their empty shells, falling to
the bottom, form the main constituent of the " Globigerina ooze "
(see p. 138).

Globigerina bulloides, d'Orb. (Fig. 49), the most abundant species
of the genus, has globular chambers forming a "rotaline" test,
each opening by a separate orifice into the deep umbilical space
on the "inferior"1 surface. The chambers increase rapidly in
size, as the series is followed, and there are three or four in the
terminal convolution.

The walls of the chambers are perforated by pores, and
at first are thin and smooth. As the shell increases in thickness,

1 See the characters of Rotalidae, p. 145.

ii8 THE FORAMINIFERA

it generally becomes areolated on the surface, the deposit being
greatest between the pores, so that these open into cup-shaped
depressions, separated by ridges. In many, but not all pelagic
specimens the shell is produced on all sides into radiating cylindri-
cal spines which spring from the points where the ridges meet,
and may exceed the diameter of the shell in length.1

A large proportion of the individuals, which in their earlier
stages conform to the type of Globigerina bulloides, complete their
growth under this form ; but for others a different future is in
store. Having attained a size which may be equal to that of the
full-grown test of the other specimens, or may fall considerably
short of it, these secrete a large spherical chamber which usually
encloses the whole of the previously formed test, and is frequently
more than double its diameter (Fig. 49, right-hand cut). The
enclosed test is usually only connected with the investing wall at
the points where its spines meet the wall and unite with it.
The investing chamber is perforated by large pores, with a
diameter of from 13-21 /A, as well as by minute pores (5-6 //).
The specimens which form the spherical chamber have been
given the generic name Orbulina. It will be convenient to use the
terms Orbulina chamber, and Globigerina chambers for the invest-
ing and the invested chambers respectively.

Unlike the Foraminifera which creep over the sea-bottom, the
pelagic Globigerinae may be found invested with a vacuolated
covering which is in part gelatinous (38, p. 6), though traversed
by radiating pseudopodia which project beyond it. This en-
velops the whole shell and the bases of the spines, and has a
spherical contour. It is probable that the Orbulina chamber is
secreted at the surface of this vacuolated mass. A similar cover-
ing may be found investing the Orbulina shell in the later phases
of the life-history.

As in the free Globigerina, the outer surface of the Orbulina
chamber is beset with spines, which vary greatly in length, and
specimens have been found, though rarely, the surface of which is
areolated by ridges as in Globigerina. These have been separated
under a distinct name — 0. porosa, Terquem.

Rhumbler finds that, in pelagic specimens, the Globigerina
chambers are always present within the Orbulina shell, though,

1 Sir John Murray thus describes the appearance of the living animal : " In
Globigerina bulloides (hirsuta) and aequilateralis the yellow -orange colour of the
sarcode is due to the presence of numerous oval-shaped xanthidiae or ' yellow cells,'
similar to those found in the Radiolaria. When the sarcode with these ' yellow
cells ' flows out of the foramina, and mounts between the numerous spines outside
the shell, the whole presents a very striking object under the microscope ; the trans-
parent sarcode can be seen running up and down the long silk-like spines, and the
'yellow cells ' seated at the base of these spines quite obscure the body of the shell."
— Nat. Science, July 1897, p. 20.

THE FORAMINIFERA 119

owing probably to the solvent action of the sea- water, they are
often reduced to fragments, or absent in bottom specimens.

The GloUgerina chambers contained in the Orbulina shell differ
from the free GloUgerina bulloides in no respect, except in the ex-
treme thinness of their walls, and Rhumbler (38) is inclined to
separate the thin-walled shells hitherto classed under that species
as the young stages of Orbulina universa, d'Orb. Rhumbler also
points out, however, that in GloUgerina bulloides, var. triloba, Reuss,
which is characterised by the large size of the three last chambers,
but not by the thinness of the shell, all variations are found be-
tween a terminal chamber which is folded back on its predecessor,
and one which completely envelops the other chambers, as in
Orbulina. The existence of these transitional forms in a variety
with a shell of the usual thickness raises the question whether the
GloUgerina chambers enclosed in the Orbulina shell were so thin
when free, or owe their thinness to the action of the protoplasm
after their enclosure.

However this may be, we have the fact that some specimens
classed as GloUgerina bulloides end their individual existence in the
GloUgerina form, while other specimens, little or not at all distin-
guished from them in the early part of their growth, become en-
veloped by an Orbulina shell. These have been classed under a
separate genus as Orbulina universa. The close resemblance between
these two sets of specimens in the early stages of growth, and also
between the Orbulina shell and that of the free GloUgerina, in the
varying development of the spines and the surface sculpture,
strongly suggests that there is some more intimate relationship
between them than that of allied genera, but what its precise
nature may be is still very obscure.

A large inflated terminal chamber is also found in Cymbalopora
bulloides, and in the littoral Pulvinulina lateralis, Terquem, and
these, like the Orbulina chamber, are also perforated by large
pores. Cymbalopora was taken in numbers by the Challenger,
as a pelagic form, in the neighbourhood of coral reefs, and,
according to Murray, every shell was filled with minute monadi-
form bodies.1 This observation would suggest that the inflated
chamber may go with the megalospheric form, but though
Rhumbler finds a single large nucleus in all the specimens of
Orbulina he examined, the same was true of the free Globigerinae.
The size of the central chamber of the included test of Orbulina
varies, according to Schacko (39), from 16-23 //, in diameter,
while in the free GloUgerina it varies from 7-20 p. Neither in
the size of the central chamber, nor in the character of the nuclei,
therefore, have we at present direct evidence for dimorphism
among these animals. As to the modes of reproduction of Globi-
1 Brady (3), p. 639, footnote.

120 THE FORAMIN1FERA

gerina or Orbulina almost nothing of a definite character is
known.1

ORDER Eotalidea.

Schlumberger has found Rotalina pleurostomata, Schlumb.
( = Pulvinulina partschiana, d'Orb.), to be dimorphic (51), and I
have found the same in Rotalia, beccarii, Linn. Among seven
examples of this species six were megalospheric, and one micro-
spheric. In these M = 55 //, (limits of variation 37 and 65 //,), and

191

b

FIG. 50.
Rotalia fteccarii, L., seen from the superior (a) and inferior (b) surfaces, up, aperture, x 30.

m - 1 3 /A. There appears to be no difference in the mode of
arrangement of the chambers in the two forms, but the nuclear
characters agree with those of Polystomella. I have observed the
production of a brood of megalospheric young by a microspheric
parent of this species, the process agreeing with that described in
Polystomella (20, p. 436).

Similarly in Calcarina hispida, Brady, M = 49 //, (limits of varia-
tion in twelve examples 39 and 59 /*,), m= 13 /* (limits 12 and
14 /A), and here, again, I found a microspheric specimen with
megalospheric young, which in this case were contained within
the parent shell.

The rose-coloured adherent tests of Polytrema are common on
coral and other objects from tropical and sub-tropical shores.
They may be depressed and encrusting, but frequently rise from
an expanded base into arborescent forms. They are built up for
the most part of numerous successive laminae of hard perforated
shell substance, produced inwards at short intervals into hollow
pillars (Fig. 51, a, p), which are connected with the underlying
shell lamina. The openings of the pillars of the superficial layer

1 The fact that the Orbulina chamber is formed in the later stages of growth of
the individual, which in its earlier stages formed the enclosed Globigerina chambers,
was first definitely stated by Rhumbler (34). The view had, however, been previously
suggested by Major Owen (32, p. 147).

THE FORAMINIFERA 121

give rise to the deep pitting of the surface from which the genus
is named. Except in the early stages of growth there is no sub-
division of the test into definite chambers. The protoplasm is
contained between the laminae, and in irregular spaces which
occupy the axes of the branches ; it communicates with the
exterior by the numerous perforations in the laminae, and at the
ends of the branches where the axial spaces open widely. Their
mouths are often beset with sponge spicules, which appear to be
used as a temporary scaffolding for the support of the extended
pseudopodia, in advance of the proper wall.

At the base, however, in contact with, or close to, the object
to which the Polytrema adheres, a spiral group of chambers is found
— the initial stage of the test (Fig. 51, a, E, and b and c). These
initial chambers have the thick coarsely perforated walls, the
abundant chitinous element, and the spiral arrangement character-
istic of the order Rotalidea.

In ten specimens of the megalospheric form, I find that M varies
from 110 to 29 /*, its average value being 51 p.. In these
specimens there are generally three chambers, following the
megalosphere, arranged in a simple spiral (Fig. 51, c) ; the fourth
chamber usually communicates by apertures with two or more
chambers, and after this the arrangement becomes more and more
irregular, all distinction between the chambers and connecting
passages is gradually lost, and the laminate structure of the test is
attained.

I have not happened to meet with specimens of the microspJieric
form, but this has been described by Merkel (23) x who finds that
the microsphere (size not given) is succeeded by a regular spiral
of some eleven chambers, before the chambers assume the irregular
transitional character.

In some cases the spiral of initial chambers is separated from
the supporting object by a layer of small chambers of the irregular
transitional form, and Schlumberger (56) has found in sand from
the Azores small examples of the megalospheric form as free
globular tests, consisting of the large initial chambers invested on
all sides with a layer of small ones. It is evident, therefore, that
Polytrema may pass through a more or less prolonged period of
free life before it becomes adherent.

Merkel found the nuclear condition to agree with that of
Polystomella, three examples of the megalospheric form containing a
single large nucleus lying in the megalosphere or an adjoining
chamber, while in one of the microspheric form four nuclei were
counted.

1 In the megalospheric form, Merkel describes the megalosphere as communicat-
ing directly with some three of the surrounding chambers — a condition which I have
not met with.

122

THE FORAMINIFERA

Polytrema was associated by the earlier naturalists with various
animals classed as " zoophytes," and was included by Pallas and

a.

FIG. 51.

Polytrema miniacemn, Liun. a, section of the test passing along the axis of a branch, and
through the stem of a Polyzoan (P), to which the test was adherent ; p, the hollow pillars be-
tween the laminae ; R, the group of rotaloid chambers, the initial stage of the test, x 20.
6, the group of rotaloid chambers (a, R), x 78 ; s, the surface of attachment to the Polyzoan ;
ch, the chitinous lining of a chamber, c, central part of the base of a young test decalcified and
treated with caustic potash, seen from the surface of attachment. The chitinous walls of the
chambers remain. M, the megalosphere, 1-4, the first four of the spiral series of chambers, x 78.

Gmelin in the genus Millepora. Its Rhizopod affinities were first
recognised by Dujardin, and its relation to Tinoporus by Carpenter.

THE FORAMINIFERA 123

Max Schultze was the first to demonstrate the spiral arrangement
of the early chambers, and its dimorphic character was shown, as
we have seen, by Merkel.

The life -histories of Patellina corrugata, Will, and Discorbina
globularis, d'Orb., as exhibited by specimens living in aquaria, have
been investigated by Schaudinn (45). Ordinarily the protoplasm
contains many granules which, during life, obscure the nuclei, but
by excluding animal food, and limiting the diet to the diatoms
growing on the sides of the vessels, Schaudinn succeeded in ren-
dering the nuclei visible, so that their changes could be followed
in the living animal.

The form of reproduction observed was that comparable
with the production of broods of megalospheric young by a
megalospheric parent, and Schaudinn's account of the changes
which the nuclei undergo is the fullest which we yet have of their
behaviour in this phase of the life-history of the Foraminifera.

All the specimens which came under notice contained a single
nucleus in their early stages. As the reproductive phase approached
the nucleus became segregated into a number of parts (usually
7-10), which were dispersed in the protoplasm, and in some cases
became subdivided by a similar process, so that there may be as
many as 30 nuclei of unequal sizes. The protoplasm becomes
divided up about the nuclei into masses proportional to them in
size, and the young thus produced repeat in turn the same cycle
of development. In Discorbina the division to form the young
occurs within the parent test, from which they escape by the
resorption of its walls. In Patellina it occurs in the large umbilical
space, i.e. outside the parent test. Schaudinn is inclined to the con-
clusion that in these species the stage in which zoospores are pro-
duced has been lost from the life-history, and that reproduction
takes place only in the manner described. Thus he regards these
species as having been originally dimorphic, but now monomorphic.

I have measured the central chambers of a number of stained
and mounted specimens of Discorbina globularis collected from the
seashore, and the results are shown in Fig. 52. It will be noticed
that in this species the central chamber is on the whole remarkably
small. In the great majority it varies in size from 12 to 31 /A, the
average of 159 specimens being 19 /*. In one case it was only
9 //, in diameter.

In this species the chitinous element of the shell is very
abundant, and forms an obstacle to the penetration of staining
reagents, but 54 of these specimens afford an indication of the
nuclear condition. In 48, including two with a central chamber
16 p. in diameter, a single nucleus is present, and in one of the
remainder a large nucleus is killed in the process of breaking up

124

THE FORAM1NIFERA

into fragments. In the specimen, the central chamber of which
measures 9 /A in diameter, 6 nuclei are clearly seen. In the 4
remaining multinuclear specimens the mean diameters of the
central chambers are 22, 18, 12, and 12 /*.

Now it is possible that all these examples of DiscorUna belong
to a single series illustrating the phases of the life-history which
Schaudinn has followed in aquaria, but the coincidence of the
occurrence of the multinuclear condition with the very small
central chamber, 9 /x in diameter, suggests that DiscorUna is, like
its allies, a dimorphic form. On this view we may regard the
specimens with a single nucleus as megalospheric, and the specimen

Fio. 52.

Table showing the dimensions in micromillimeters of the central chambers of 159 specimens of
Discorbina globularis, d'Orb.

with (at least) 6 nuclei and a central chamber 9 p. in diameter as
microspheric. The remaining multinuclear specimens may consist
of megalospheric individuals, the nucleus of which is breaking up
prior to reproduction, or of microspheric individuals with a larger
microsphere, or, and more probably, of both kinds.

On this view the form of reproduction which Schaudinn
described in DiscorUna is the production of megalospheric young
by a megalospheric parent which is, as we have seen, of frequent
occurrence in other genera.

The formation of zoospores by the megalospheric parent was
not observed among the specimens kept in aquaria, but we are
still at liberty to suppose that this phase of the life-history may
occur in the natural state.

Truncatulina lobatula, W. and J., affords another instance of the

THE FORAMINIFERA 125

approximation of the megalosphere to the size of the microsphere.
Thus in 13 examples I found 12 to be megalospheric and
the value of M to be, on an average, 28 /*, varying from 36
to 1 5 p. The other specimen is microspheric, and m = 1 1 p..
The nuclear characters corresponded to those described in Poly-
stomella (20).

Plastogamy. — This remarkable and little understood process
which has been observed in other groups of Protozoa was found
by Schaudinn to be frequently associated with the reproduction of
Patellina and Discorbina. In the former the pseudopodia of two in-

FIG. 53.

View from the under side of two specimens of Patellina corrugata, Will., which have united
in plastogamy prior to the breaking-up of the united protoplasm to form a brood of young.
1, young of varying size ; 2, nucleus of a young individual ; 3, accumulations of detritus.
(After Schaudinn, 45.)

dividuals that have come, apparently by chance, into juxtaposition
fuse, and form a uniting band which increases in thickness until
all' the extruded protoplasm is involved in it, and the tests are
drawn close together. The nucleus in each meanwhile divides in
the manner above described. Gradually the protoplasm of both
emerges into the space between the bases of the approximated
tests and the surface to which they are attached, and then, as in
the reproduction of a single individual, divides up about the nuclei
to form a brood of young (Fig. 53). As many as five individuals
may thus unite. In no case did Schaudinn observe any fusion
between the original nuclei or the fragments into which they
divided. He also found that the process only occurred when the
nuclei of the individuals which met were in the same phase of

126

THE FORAMINIFERA

development ; thus a one-nucleated individual and an individual
whose nucleus had begun to divide would not unite.

In Discorbina a similar process was observed ; but in this case the

two individuals came together
base to base, and the pair
wandered about for a consider-
able time before the young
were produced. In some cases
a deposit of lime between the
opposed bases occurred in the
interval, so that after the escape
of the young the empty parent
shells remained united together. The
remarkable pairs of shells which have
been observed in Discorbina, Textularia,
and Bulimina (Fig. 54) are, probably,
thus explained.

Fio. 54.

Paired tests of a species of Buli-
mina from Delos. In a the paired
individuals are of equal, in b of
very unequal size. From speci-
mens kindly given me by Mr. H.
Sidebottom.

ORDER Nummulitidea.

The members of this order are dis-
tinguished by their bilaterally sym-
metrical tests, which in the early stages
or throughout growth are arranged
on the spiral plan ; by the double character of the septa between
the chambers, containing branches of the highly developed canal
system interposed between the laminae ; by their hard perforated
Avails ; and by the slit-like aperture (subdivided in Polystomella)
situated between the inner margin of the septum and the wall of
the previous convolution.

The structure of Polystomella is described above (pp. 62 et seq.).
Nonionina is a simpler form of the same type, characterised by the
scantiness of the umbilical deposit, the absence of retral processes,
and the fact that the aperture is not subdivided into pores, as in
Polystomella, but remains a simple slit.

Amphistegina is transitional in structure between the Rotalidea
and Nummulitidea ; it has simple septa, and the test is not truly
symmetrical, the spire being (as in the Rotalidea) slightly helicoid
and the aperture on one (the " inferior ") side of the median plane.
In the marked development of the alar prolongations it approaches
the genus Nummulites.

In Operculina (Fig. 55) the chambers are simple and disposed in
an expanding spiral, some three or four convolutions completing the
test. The earlier chambers are produced to a greater or less
extent into alar prolongations, and thus a boss-like umbo is formed
at the centre ; but the later chambers are simply applied to the

THE FORAMINIFERA

127

margin of the previous convolution, and have a large radial extent.
The aperture is crescentic and undivided, but is supplemented
by pores distributed along the
septum.

The canal system is highly
developed, a plexus of canals,
in connection with the meri-
dional vessels, running in a
keel -like thickening at the
outer rim of the test.

A sample of sand obtained
by Mr. J. Stanley Gardiner
from Suvadiva in the Maldive
Archipelago consists for the
most part of the tests of Oper-
culina complanata and Hetero-
stegina depressa, d'Orb. Of the
former I have found two speci-
mens of the microspheric form,
in both of which m = 27 /*, and
the second chamber is very
minute (Fig. 55, B).

In five specimens of the meg-
alospheric form the values of
M vary from 45 to 63 p and
have an average of 54 /*.

I have not observed that
the tests of the two forms of
this species are distinguished
by a difference in size.

In Nummulites the chambers are of very small extent in a
radial direction (Fig. 6), so that each convolution adds little to the
diameter of the test, and the outline of the latter is nearly circular.
The number of the convolutions is however very large. The
alar prolongations, on the other hand, are highly developed, and
extend nearly to the centre. As the chambers of each successive
convolution are thus produced, the result is that the tests are
strongly biconvex, the spiral axis measuring from one -third to
three-quarters of the diameter. The alar prolongations of the
chambers may be directed straight towards the spiral axis (radiate,
type) or take a sinuous course (sinuate type), or they may be
replaced by a number of separate chamberlets forming when
exposed in worn specimens a network over the surface (reticu-
late type). The aperture and canal system resemble those of
Operculina.

The microspheric form attains, as we have seen, a much

Fio. 55.

Operculina complanata, Def. m, a complete
test, x 8 ; A, central part of section of megalo-
spheric form ; B, of the microsplieric form. (A
and B, x 50.)

128 THE FORAMINIFERA

greater size than the megalospheric (Fig. 5). I am not aware of
any record of the actual size of the microsphere.

In the megalospheric forms M is very large, attaining in some
cases 1 mm.

While Operculina is closely connected on the one hand with
Nummulites, it forms, on the other, the simplest term of a series
— Operculina, Heterostegina, Cydodypeus, which presents among
the Nummulitidea a remarkably complete parallel to the Peneroplis,
Orbiculina, Orbitolites series in the Miliolidea.

In Heterostegina (Fig. 56) the arrangement of the chambers is
spiral, though they become somewhat more embracing as age
advances. The chambers which are first formed are simple, as
in Operculina, but they soon become subdivided by partitions which
are disposed perpendicularly to the plane of the spiral, and, on the
whole, transverse to the long diameter of the chambers. The
chambers are thus subdivided into more or less quadrangular
chamberlets. As in Operculina, the chambers of the inner convolu-
tions are produced into alar prolongations (which are, however,
not subdivided into chamberlets), while the later chambers are
simply applied to the edge of the preceding convolution. The
arrangement thus presents considerable resemblance to that of
Orbiculina, but in addition to the presence of the canal system,
perforate walls, and double septa, there is also a marked difference
in the mode of communication of the chamberlets, for here the
adjacent chamberlets of a chamber do not communicate directly
with one another, but each communicates as a rule with two
chamberlets of the preceding and with two of the succeeding
chambers. (These communications are not displayed in the
sections figured, but may be readily seen in the protoplasmic
casts of decalcified specimens.)

The canal system is well developed and resembles that of
Operculina, a marginal plexus being present here also.

In the sample of sand from the Maldive Islands, above men-
tioned, the great majority of the specimens of Heterostegina range
from a small size up to about 4 mm. in their larger diameter (Fig.
56, A), but a few far exceed the rest, attaining a diameter of 10
or more mm. (Fig. 56, B). I am unable to recognise any differ-
ence in the external appearance of the two forms, beyond that
in size, and the peculiar shape of the large specimens caused
by the greater width of the terminal convolution. On making
sections of the tests it is found that the large specimens are
microspheric and the smaller ones megalospheric.

In two specimens of the former m=27 p in both, and a spiral
of some 36 simple chambers succeeds before the septa appear,
dividing the chambers into chamberlets (Fig. 56, B').

In the megalospheric form M varies in four cases from 70 to

THE FORAMINIFERA

129

Kio. JO.

HeterostegiiM depressa, d'Orb. A and B the uiegalospheric and microspheric forms, x 8.
A', B', central regions of sections of these tests in the median plane, x 50. The figures 14 and
38 mark the first of the subdivided chambers, in the two forms respectively. The canal system
is barely indicated in this figure and in figure 55.

130 THE FORAMINIFERA

80 ft, and the number of single chambers is 9 to 12. In some
cases the chamber which succeeds the megalosphere is consider-
ably larger than those which immediately follow (Fig. 56, A').

We thus have in this sand from the Maldives a difference in
size between the two forms of Heterostegina similar to that found
in the Nummulitic formations of the Eocene period.1

In the third genus of the series, represented by the species
Cydodypeus carpenteri, the great majority of the individuals do not
exceed 12 mm. in diameter, but some attain the large size of
64 mm.

It is very probable, from analogy with other genera, that the
specimens which attain the large size are microspheric ; those of
smaller size are, in the specimens which I have examined, megalo-
spheric.

The only specimen (Figs. 57, B, and 58) of the microspheric form
which I have examined is a section.2 In it the microsphere
measures 29 /A, and is followed by 9 single chambers arranged
in a spiral. The chambers then become subdivided, as in
Heterostegina. After being disposed at first in a spiral, they
gradually extend round a larger and larger part of the circum-
ference of the test until they completely encircle it, and the
arrangement becomes annular. The twenty -fifth chamber from
the microsphere is, in this specimen, the first to complete the
circle.

In the megalospheric form the centre is occupied by a structure
somewhat resembling the " primitive disc " of Orbitolites complanata
(p. 106). It is, however, differently constituted. The megalo-
sphere is very large, its average mean diameter in 9 cases being
245 fj., and the extremes 465 and 175 p.. It communicates by a
narrow neck with a large chamber which is applied to the megalo-
sphere for about half its circumference, and communicates in
turn with another large chamber.

1 Chapman (10, p. 19) believes that he has found the dimorphic forms of Hetero-
stegina, and identifies them with the biconvex and the compressed varieties described
by Brady. He finds that the size of the full-grown megalospheric test is greater than
that of the microspheric, a result which he recognises as unusual. The relative sizes
of M aud m are said to be iu the proportion of 3:2, and I learn from Mr. Chapman,
by letter, that the actual diameters were 125 and 65 fj. respectively. These results
are so far at variance with the phenomena of dimorphism in general, and with my
own in this species, that it appears probable that the individuals with the smaller
central chamber were megalospheric specimens with rather smaller megalospheres,
and that Mr. Chapman did not meet witli the microspheric form.

2 I have to thank Professor J. W. Judd for the opportunity of examining and
figuring this section. The specimen was obtained at Funafuti, in the Pacific, and
the section was prepared by Mr. Chapman, and figured by him (10, PI. III. Fig. 2)
on a small scale. In this paper the specimen is regarded as an unusual example of
the megalospheric form, but I understand, by letter, from Mr. Chapman that he is
now inclined to reconsider this view. Fis. 58 is prepared from a photograph of the
central region, on a larger scale, and Fig. 57, B, shows the arrangement of the
chambers more clearly.

THE FORAMINIFERA

The arrangement of the chambers which succeed varies in
different specimens. In some (as in Fig. 57, A) a succession of
about six subdivided " heterostegine " chambers follows, which

Fio. 57.

Cycloclypeus carpenteri, Brady. HI, a complete test, x 8. A, central region of a decalcified
specimen of the megalospheric form, x 85. B, central region of a section of the test of the
microspheric form, x 50. The canal system is not seen in these figures. The figures 1 and 9
in B mark the first and last of the undivided chambers, 20 is a heterostegine chamber, and 25
the first of the annular chambers.

become more and more embracing, until they extend completely
round the previously formed chambers. The annular arrangement
once attained is continued, though not without irregularities of
growth, till the test is complete. The mode of communication of

132

THE FORAMIN1FERA

the chamberlets with one another is similar to that described in
Heterostegina. The variations on this arrangement which occur
result from a more speedy attainment, in different degrees, of the
cyclical growth. Where the nuclear characters have been recog-
nised, a single large nucleus was found in one of the large central
chambers of the megalospheric form.

FIG. 58.

Photograph of the central part of the section of Cyclodypeus carpenteri (microspheric) repre-
sented in Fig. 57, B.

Looking back on the evidence furnished by these three genera
we find that Operculina is built on the same plan in both micro-
spheric and megalospheric forms ; that Heterostegina repeats the
operculine condition in both forms, though the number of un-
divided chambers is greater in the microspheric form than in the
megalospheric ; and that Cyclodypeus repeats both the operculine
and heterostegine conditions in the microspheric form, while in
the megalospheric the operculine stage is omitted or represented

THE FORAMINIFERA 133

only by the two large chambers which succeed the megalosphere,
and the heterostegine stage is considerably shortened. In fact,
we find the same tendency in the megalospheric form to abridge
or omit the stages repeated by the microspheric form as we have
seen in other cases.

The genus Fusulina is represented by a series of forms which
abound in the Carboniferous and Permian rocks in Russia, North
America, Sumatra, and elsewhere. By their perforate walls, their
bilateral sym-
metry about a
median plane,
and the charac-
ter of the aper-
ture, which is a

c

FlO. SO.

Forms of the genus Fusvlina from the Carboniferous formation of Russia,
showing varying degrees of elongation in the direction of the spiral axis, com-
parable with those of the Miliolid Alveolina. A, F. aequalis (d'Eichwald) ; B, F.
sphaeroidta (Ehrbg.) ; C, F. princeps (Ehrbg.) ; D, F. cylindrica (Fischer). From
Brady, Ann. and Mag. of Nat. Hist. 4, xviii. p. 414.

slit left between the margin of the septum and the surface of
the preceding convolution, they appear to belong to the Nurn-
muline stock. Like the species of Alveolina they present varying
degrees of elongation in the direction of the spiral axis from the
biconvex discs of F. aequalis (Fig. 59, A) to the fusiform tests of
F. cyclindrica (D).

The megalospheric and microspheric forms of Fusulina have
been recognised by Schlumberger (58).

We may now take a brief survey of some of the main pheno-
mena which have presented themselves in the several groups.

Among the species of Foraminifera we meet with modifications
of form of three kinds. There is the modification which occurs
during the growth of an individual, producing the "multiform"
condition of test. There is the difference among individuals
dependent on their mode of origin, whether from a megalosphere
or a microsphere, which finds its expression in dimorphism. Finally,
there is the variation commonly presented to a greater or less
extent by animals and plants, the departure of the individual in
different degrees from the type form of the species.

We may consider these three kinds of modification in the
reverse order.

The Variation of the Foraminifera. — It has long been recognised
by systematists that in many cases the limits of the characters of
the species of Foraminifera do not admit of being drawn with any

134 THE FORAMINIFERA

exactness. This view was insisted on by Carpenter, who, in the
" Challenger " Report on Orbitolites (p. 9), quotes with approval the
doctrine that among the porcellanous and vitreous Foraminifera
" everything passes into everything else."

Carpenter, indeed, held (I.e. p. 8) that "the ordinary notion of
species as assemblages of individuals marked out from each other
by definite characters that have been genetically transmitted from
original prototypes similarly distinguished, is quite inapplicable to
the group of the Foraminifera." And again, in the Introduction we
read (8, p. 56): — "The impracticability of applying the ordinary
method of definition to the genera of the Foraminifera becomes
an absolute impossibility in regard to species. For whether or
not there really exist in this group generic assemblages capable
of being strictly limited by well-marked boundaries, it may be
affirmed with certainty that among the forms of which such
assemblages are composed, it is the exception, not the rule, to
find one which is so isolated from the rest by any constant and
definite peculiarity, as to have the least claim to rank as a natural
species."

The question, however, appears to be not whether all inter-
mediate terms do or do not exist between dissimilar forms, but
whether the whole body of forms, as they occur in nature, tend to
group themselves, or are aggregated about certain centres. If this
is the fact, and the forms, as they occur in nature, are disposed not
in a continuous series, but in a discontinuous one, the large number
of individuals being grouped about distinct centres, we have the
phenomenon which is comparable with that of species in other
animals and in plants, whether the centres are or are not connected
by intermediate terms. To refuse to recognise the existence of these
centres, because transitional forms exist between them, is to ignore
an essential fact.

In a very large number of cases, at any rate, such centres do
exist among the Foraminifera, as among other organised beings,
and the characters of the middle individuals of them are those of
the species.

The dimorphism of Foraminifera depends, as we have seen, on
two modes of reproduction, which recur in a cycle of generations.
The megalospheric form arises by the multiple fission of a single
parent, while there are strong grounds for concluding that the
microspheric form arises from a zygote, formed by the conjugation
of zoospores.

The phenomena of dimorphism are exhibited in the size of the
initial chambers, in the nuclear characters, in the mode of reproduc-
tion, and, often, in the plan of growth. In most of the species of
Foraminifera in which we have evidence of the sizes of the initial
chambers, they are strongly contrasted in the two forms, although

THE FORAMINIFERA 135

in some, as in Peneroplis, the size of the megalosphere may, in
exceptional cases, fall below that of the microsphere. In this
genus, as we have seen, the microspheric form is also to be dis-
tinguished by the absence of the spiral passage. In Discorbina and
Truncatulina there is no such structural feature to distinguish the
two forms, nor are they always to be recognised by the size of
the central chambers. There is reason to believe, however, that
they differ in nuclear characters, and mode of reproduction.
Whether or not the two modes of reproduction prevail through-
out the simpler forms of Foraminifera cannot at present be
stated.

The Multiform Condition. — The significance of this condition is
one of the most interesting problems presented by the Foraminifera.
Perhaps the simplest case of its occurrence is that of Polytrema
(p. 120). We have seen that in the earliest stages of life this
organism is free, and secretes a test which resembles in many of
its features that typical of the Rotalidae. After it has become
adherent the rotaline mode of growth is exchanged for one
adapted to the attached habit, and the test assumes an encrusting
or arborescent form.

In the case of Polytrema, then, it seems clear that the arrange-
ment of the chambers formed early in life repeats that of the
rotaline stock from Avhich it sprang, while the later chambers are
disposed on a plan acquired as it has diverged from that
stock.

Again, the more complex members (Orbitolites and Cydodypeus)
of the Peneroplis-Orbitolites and Operculina-Cydodypeus series present
excellent examples of the multiform condition. The facts that
each of these is a series of closely related genera, and that the
simpler members of each present in a permanent form the arrange-
ment which is transitory in the growth of the more complex,
appear to give substantial support to the view urged by Car-
penter that the stages which we have called peneropline and
orbiculine, operculine and heterostegine, in the growth of Orbitolites
and Cydodypeus respectively, are, in fact, repetitions in ontogeny
of a phylogenetic history.

The application of this explanation to the multiform Miliolinidae
appears less satisfactory because the earlier (quinqueloculine) plan
of growth is somewhat more complex than the later, and we should
not therefore expect it to be the more primitive. We need not
assume, however, that the course of development has always been
in the direction from simple to complex.

Closely connected with this question is the fact that the multi-
form condition is, as we have seen, much more pronounced in the
microspheric than in the megalospheric form of a species. In a
former paper I suggested (21) that a partial explanation of the

136 THE FORAMINIFERA

contrast may be found in the difference in the mode of origin
of the two forms.

The life-history of the Cladoceran Leptodora hyalina, appears to
offer a similar contrast. Throughout the summer months broods
of young are produced, which develop parthenogenetically and
are hatched in the form of the parent. The resting winter
egg, on the other hand, which develops as the result of fertilisa-
tion, emerges as a Nauplius larva — the form in which the members
of such diverse families take their origin, and which, there is good
reason to believe, repeats in several of its features the characters
of the primitive Crustacea.

In the case of Leptodora we see that after, and apparently as the
result of, fertilisation the organism " casts back " in its develop-
ment, repeating primitive features which are abbreviated or absent
in the development of the form arising without a sexual process.
Now although the megalosphere of the Foraminifera, the product
of the multiple fission of the parent, may not be strictly comparable
with the unfertilised egg of Leptodora, it has, at least, this in
common with it, that it arises asexually, while it is probable that
the microspheric form arises from the conjugation of gametes, a
process comparable to the fertilisation of the Metazoa. In the
paper referred to it was suggested that the accentuation of the
multiform character of the microspheric form of the Foraminifera,
as compared with the megalospheric, is likewise dependent on the
process of fertilisation.

It still appears to me possible that the explanation may
be found in the direction indicated, but that this is not the
complete solution is shown by consideration of the Initial Poly-
morphism displayed by the megalospheric forms of several
species. In Idalina and Orbiculina we have seen that the extent
to which the phases of growth which occur in the development of
the microspheric form are repeated by the megalospheric form
varies in different individuals, and that it is correlated with the
size of the megalosphere — individuals with small megalospheres
repeating these phases more completely than those with large
megalospheres. What the cause of this correlation may be
appears entirely obscure, but it is evident that if among the
megalospheric forms, arising asexually, the completeness of the
repetition of the earlier phases depends on the size of the central
chamber, we are not at liberty to refer the completeness of
their repetition in the microspheric form wholly to its sexual
origin.

In his sketch of a natural classification of the Foraminifera (36 and 37)
Rhumbler takes altogether different views of the phenomena we have
been considering, and the classification proposed as the result has been
adopted by Lang in the new edition of his Lehrbuch.

THE FORAMINIFERA 137

In Rhumbler's view " Festigkeitsauslese," the selection of the forms
of test best adapted to resist mechanical stress, is regarded as the chief
factor which has dominated the differentiation of the Foraminifera,
and several series of genera, such as the Nodosaria-Cristdlaria, and the
Biloculina-Quinqueloculina series, are given as examples of a " Festigkeit-
skala " in which varying degrees of resisting power have been attained.

In the biformed and triformed tests the early chambers are regarded
as arranged on a higher (i.e. more resisting) plan than those added later,
and hence it is concluded that in the ontogeny of the Foraminifera the
order of the appearance of the more primitive and the later acquired
characters is the reverse of that so general in the development of other
animals, the earlier arrangement representing the form towards which
the race is advancing, the later retaining the characters which will ulti-
mately be discarded.

This reversal of the usual order is attributed to the great delicacy of
the young test, to compensate for which a more compact arrangement of
the chambers has been acquired. In the later stages of growth, owing to
the larger bulk of the protoplasm, the chamber walls can be secreted of
such a thickness as to counterbalance the mechanical weakness of their
arrangement.

The contrast in the modes of growth of the megalospheric and micro-
spheric forms is similarly explained, the small size of the latter in the
early stages of growth calling for an arrangement, which is less urgently
needed in the later stages, or by the megalospheric form. In the more
perfected genera, however (as Quinqueloculina), the tests of the forms of
both generations are moulded on the most compact type.

Thus Rhumbler, like Carpenter, regards the multiform tests of
Foraminifera as of great value in tracing out phylogeny, but for precisely
opposite reasons, for while Carpenter considers the early phases as repre-
senting a stage through which the stock has passed, Rhumbler sees in
them the higher stage towards which it is advancing.

As will be gathered from what has gone before, it does not appear
to me that sufficient reason has been shown for discarding the view of
Carpenter.

Another remarkable phenomenon met with among the Fora-
minifera is that of Isomorphism. It may be denned as the occurrence
under similar external forms of species belonging to distinct
stocks.

Perhaps the most striking instance of it is presented by the
Miliolidea and Nummulitidea. It has been pointed out how in
the latter family the series Operculina, Heterostegina, Cydodypeus runs
parallel with the Peneroplis, Orliculina, OrUtolites series of the'
Miliolidea, and we have seen that in Heterostegina, as well as in
Polystomella and other allied genera, the tests are to some degree
extended in the spiral axis owing to the equitant character of
the chambers. The resemblance between the corresponding terms
in the two series is rendered all the more remarkable by considera-
tion of the forms included in the genus FusvUna, which, at the

138 THE FORAMINIFERA

period when the Carboniferous and Permian rocks were deposited,
had undergone elongation in the direction of the spiral axis and
been differentiated into a series of forms — biconvex, obovate,
spheroidal, and fusiform — closely comparable with those assumed
by the species of Alveolina of the Tertiary period and the present
day (cp. Figs. 42 and 59).1

Distribution. — From this point of view the Foraminifera may be
divided into two classes — the attached or bottom-living and pelagic
forms. While by far the greater number of genera and species
belong to the former, the numbers of individuals of the latter are
enormously great.

The Pelagic Foraminifera belong to the genera Globigerina (with
its connected form Orbulina), Hastigerina, Pullenia, Sphaeroidina,
and Candeina — forming the order Globigerinidea — and Pulvinulina
and Cymbalopora among the Rotalidea. The pelagic habit of these
forms, though it had previously been recognised by M'Donald and
Major Owen, was first clearly established by the naturalists of the
Challenger.

The species which are found at the surface extend down to
considerable depths, but whether they may actually live on the
bottom of the ocean is still, in spite of much discussion, undecided.
They congregate at the surface at night, and partially withdraw
from it during the day.

It is in the equatorial and temperate regions of the ocean that
they most abound, the pelagic forms being represented in the arctic
and antarctic seas by small species of Globigerina : G. paclujderma in
the former, G. dutertrei in the latter.

Beneath this equatorial belt of warm water and its northern
offset, the Gulf Stream, the empty tests of the pelagic Foramini-
fera constitute the main portion of the " Globigerina ooze," which
forms the ocean floor down to a depth of 3000 fathoms. As this
limit is approached the thinner tests disappear, and beyond it all
calcareous constituents are removed by solution.2

The species of bottom-living Foraminifera have, on the whole,
a very wide distribution. Some are cosmopolitan, ranging from
arctic to tropical waters and from shore pools to the bottom of
the great oceans. A large proportion of the genera, however, are
restricted by depth and temperature. The shallow littoral waters
of the tropics contain an abundant fauna, most of the members of
which do not extend to colder seas. On the other hand, genera

1 The Lituolidea are described as " isomorphous " with various calcareous genera,
but it is far from certain that the similarity in form does not depend on true affinity,
in which case the term is not strictly applicable. Loftusia, among the Lituolidea,
has a fusiform test, externally resembling the more elongated forms of the Fusulina
and Alveolina series.

2 Cp. Sir John Murray, " On the Distribution of the Pelagic Foraminifera," etc.
Natural Science, July 1897, pp. 17-27.

THE FORAMINIFERA 139

(such as those of the Astrorhizidea) which abound in the arctic
seas extend, as members of the abyssal fauna, along the ocean
floor, to mingle in lower latitudes with the empty tests of the
pelagic inhabitants of the warmer surface waters.

Notwithstanding the wide range of many species, there is some
indication of a limitation of forms to definite areas — the formation
of local faunas — comparable to that met with in the distribution of
other animals and of plants. Thus in the warm shallow seas
of the Malay Archipelago Mr. Millett finds the forms deviate in
many instances from the ordinary structure of the Foraminifera.1
In his reports hitherto published, dealing with the orders as far
as and including the Lagenidea, he has described twenty-six new
species and one new genus from this region.

Geological Distribution. — Representatives of four orders of the
Foraminifera — Textularidea, Lagenidea, Rotalidea, and Globi-
gerinidea — have been recognised in the Cambrian, the oldest of the
" palaeozoic " formations. In the Carboniferous all the orders are
represented except the Miliolidea — which have,however, been recog-
nised in beds transitional between the Carboniferous and the Per-
mian— the small and fragile Chilostomellidea, and the Gromiidea,
whose slight tests we should hardly expect to find preserved.
In the Carboniferous formation species of Saccammina and Fusulina
give rise to extensive deposits. An abundant foraminiferal fauna
has been found in many of the secondary formations, and the chalk
of the later Cretaceous period is in large part built up of their
tests, Gloligerina being an abundant form as in the oozes of the
existing ocean basins.

Foraminifera also enter largely into the composition of the
earlier rocks of the Tertiary period. The Miliolidea here come
into great prominence, and are represented by Miliolina (including
Quinqueloculina and Triloculina),a,nd its allies Peneroplis, Orbitolites, and
Alveolina. Nummulites, which had already made their appearance
in the Carboniferous period, also abounded in the warm shallow
Eocene seas, and the Nummulitic limestones extend across the old
world from the Pyrenees to China, attaining in some places
thousands of feet in thickness.

It need hardly be pointed out that our knowledge of the life-
history of the Foraminifera is still very far from complete. In the
establishment of the prevalence throughout the higher groups of
the phenomenon of dimorphism, dependent on different modes of
reproduction, a substantial groundwork has been attained, but
there remain many important questions of wide biological bearing
on which we are very imperfectly informed.

1 Report on the Recent Foraminifera of the Malay Archipelago collected by Mr. A.
Durrand, F.R.M.S., Journ. Roy. Microscopical Soc. 1898, p. 258.

140 THE FORAMINIFERA

There seems good reason to hope that the study of the plan
of growth of both forms of the species during the early stages of
their life-histories may throw light on the complicated problems
of phylogeny. Until these early stages have received fuller
attention, and we have arrived at a conclusion as to the relation
of the early to the later stages of the multiform tests, efforts at
forming a " natural classification " appear to be premature.

The classification adopted by Brady in his Challenger Monograph
is given here, with slight modifications. I have followed Neumayr
(30) in placing the Astrorhizidea before the Miliolidea as they
appear to be more primitive forms. The Cycloclypeinae are merged
with the Nummulitidae for the reasons given above.

It appears highly probable that the Lituolidea should be dis-
tributed (as Biitschli has done) among the calcareous forms which
they resemble, but they are here left as arranged by Brady.

In conclusion I desire to express my thanks to my brother Mr.
W. T. Lister, for his assistance in preparing the photographs of
the shells of Foraminifera with which this article is illustrated.
They were done with one of Zeiss' admirable instruments.

ORDER 1. Gromiidea.

Test membranous, chitinous, or siliceous ; smooth or encrusted with
foreign bodies ; with one or more pseudopodial apertures.

FAMILY 1. POLYSTOMATIDAE. Test with one or many openings.
Genus Myxotheca, Schaudinn (Fig. 2). Test encrusted, openings many ;
marine. Here may be provisionally placed Hyalopus, Schaudinn
( = Gromia dujardinii, M. Sch.). Test smooth, rounded, with one opening
(Fig. 15), or branched, and with many ; pseudopodia hyaline, with few or
no anastomoses ; multinucleate ; marine.

FAMILY 2. MONOSTOMATIDAE. Test rounded or flask -shaped, with
a single opening.

(a) Test smooth. Genera — Gromia, Duj. Test chitinous, usually
flexible, mouth terminal ; freshwater and marine (Fig. 1). Lieberkiihnia,
Clap, and L. Test very delicate, ovoid ; moutli sub-terminal. Mikro-
gromia, R Hertw. (Cystophrys, Archer) (Fig. 14). Test small, rigid, flask-
shaped, bilaterally symmetrical, not filled by the protoplasm ; pseudopodia
springing from a short stalk of protoplasm ; individuals often united by
their pseudopodia into colonies. Platoum, F. E. Sch. Similar to Mikro-
gromia, but test more pointed. Lecythium, H. and L. Similar, but
protoplasm filling the test. These four are freshwater genera.

(&) Test encrusted with foreign bodies. Genera — Pseudodifflugia,
Schlumb. Eesembles Gromia, but test encrusted ; fresh and brackish
water. Diaphoropodon, Archer. Test ovoid, built of loosely-united foreign
bodies. Pseudopodia of two kinds : long, extended from the mouth ; and
short, hair-like (? true pseudopodia) between the particles of the test.

(c) Test built of chitinous or siliceous plates. Genera — Euglypha, Duj.
(Fig. 3). Test elliptical or pear-shaped, with terminal mouth ; built of

THE FORAMINIFERA 141

circular or hexagonal siliceous plates ; pseudopodia without anastomoses ;
freshwater. Trinema, Duj. Similar, but mouth on flattened lateral
surface ; freshwater. Cyphoderia, Schlumb. Test flask-shaped, built of
small chitinous plates ; fresh and brackish water. Campascus, Leidy
Resembles Cyphoderia, but test encrusted ; freshwater.

FAMILY 3. AMPHISTOMATIDAE. Test with an opening at either end.

(a) Test smooth. Genera — Diplophrys, Barker. Test roundish, very
delicate ; freshwater, and in manure. Ditrema, Archer. Similar, but test
thicker ; freshwater. Shepheardella, Siddall (Fig 16, 5). Test chitinous,
long, and tubular, contracted to an opening at either end ; marine.

(6) Test encrusted. Genus — Amphitrema, Archer (Fig. 16, 1 1). Barrel-
shaped, test produced to a short neck round either opening ; moor pools,
Ireland.

ORDER 2. Astrorhizidea.

Test invariably composite, usually of large size and monothalamous ;
often branched or radiate, sometimes segmented by constriction of the
walls, but seldom or never truly septate ; polythalamous forms never
symmetrical.

FAMILY 1. ASTRORHIZIDAE. Walls thick, composed of loose sand or
mud, very slightly cemented. Genera — Astrorhiza, Sandahl (Fig. 17, a).
Test fusiform, or depressed and more or less stellate, and attaining a
diameter of nearly one inch. Pelosina, Brady. Storthosphaera, F. E. Sch.
Dendrophrya, Str. Wright. Syringammina, Brady. Test consisting of
masses of branchings and anastomosing tubes.

FAMILY 2. PILULINIDAE. Monothalamous, wall thick, composed
chiefly of felted sponge spicules. Genera — Pilulina, Carpenter (Fig. 17, c).
Nearly spherical. Technitella, Norm. Oval. Bathysiphon, Sars. Tubular.

FAMILY 3. SACCAMMINIDAE. Chambers nearly spherical, walls thin,
firmly cemented. Genera — Saccammina, M. Sars (Fig. 17, 6). Globular,
with distinct projecting aperture. Psammosphaera fuscu, F. E. S., without
a projecting aperture. Is regarded by Rhumbler as the young form of
Saccamminina sphaerica. Sorosphaera, Brady. Many spherical adherent
chambers, each with its own aperture.

FAMILY 4. RHABDAMMINIDAE. Test firmly cemented, of sand,
often with sponge spicules intermixed, tubular, straight, radiate or
branched, rarely segmented. Genera — Jaculella, Brady. Elongate,
tapering. Hyperammina, Brady (Figs. 17, d, and 18). Elongated,
tubular, simple or branched, sometimes commencing in a globular chamber.
Marsipella, Norman. Fusiform or cylindrical Ehabdammina, M. Sars.
Rectilinear, radiate or branching, with or without a central chamber.
Aschemonella, Brady. Test of inflated sacs, single or combined in series.
Rhizammina, Brady. Fine chitino-arenaceous tubes, simple or branched.
Sagenella, Brady. Adherent, branching tubes. Botellina, Carpenter.
Test cylindrical of loose sand, with irregular cavities. Haliphysema, Bk.
Test columnar, attached by a stalk, simple or branched, beset with sponge
spicules (Fig. 19).

142 THE FORAMINIFERA

ORDER 3. Lituolidea.

Test arenaceous, usually regular in contour, chambers of the poly-
thalamous forms frequently labyrinthic. Comprises sandy isomorphs of
the simple porcellanous and hyaline types (Cornuspira, Peneroplis, Layena,
Nodosaria, Cristellaria, Globigerina, Eotalia, Nonionina, etc.), together
with some adherent species.

FAMILY 1. LITUOLIDAE. Test of coarse sand grains, rough ex-
ternally ; often labyrinthic. (a) Chambers non-labyrinthic. Genera —
Reophax, Montf. Test free, composed of one flask -shaped chamber, or of
several united into a straight, curved, or irregular line, never spiral.
Coskinolina, Stache ; Haplophragmium, Reuss. Test free, nautiloid, or
crosier-shaped. Placopsilina, d'Orb. Chambers plano-convex, adherent.
(6) Chambers labyrinthic. Genera — Haplostiche, Reuss. Test free, uni-
serial, never spiral. Lituola, Lamk. Test free, nautiloid, or crosier-shaped.
Bdelloidina, Carter. Adherent.

FAMILY 2. TROCHAMMINIDAE. Test thin, composed of minute sand
grains incorporated with calcareous or other cement ; smooth, often
polished externally. Genera — Thurammina, Brady. Test a single sub-
spherical chamber. Hippocrepina, Parker ; Hormosina, Brady. A
rounded chamber, or several in a straight or curved series. Ammodiscus,
Reuss. Test non-septate, coiled in a piano-spiral (resembling Spirillina)
or otherwise. Trochammina, P. and J. Free or adherent, rotaliform,
nautiloid or trochoid. Carterina, Brady. Test rotaliform, constructed
of fusiform spicules, said to be proper to itself. Jfebbina, d'Orb. One or
more adherent, stoloniferous chambers.

FAMILY 3. ENDOTHYRIDAE. Fossils. Test more calcareous and
less sandy than in other Lituolidae, sometimes perforate. Genera —
Nodosinella, Brady. Nodosariform. Polyphragma, Reuss. Involutina,
Terq. Endothyra, Phil. Bradyina, Moll. Stacheia, Brady.

FAMILY 4. LOFTUSIIDAE. Test relatively large, lenticular, spheri-
cal or fusiform ; arranged spirally, or in concentric layers ; walls finely
arenaceous and cancellated. Genera — Cyclammina, Brady. Nautiloid.
Loftusia, Brady. Large, resembling Alveolina in contour. Parkeria,
Carp. Large, spheroidal

ORDER 4. Miliolidea.

Test usually imperforate, normally calcareous and porcellanous, some-
times encrusted with sand ; under starved conditions (e.g. in brackish water)
becoming chitinous or chitino-arenaceous ; at abyssal depths occasionally
consisting of a thin, homogeneous, imperforate, siliceous film.

FAMILY 1. MILIOLINIDAE. Test of one or many chambers spirally
arranged ; in the many - chambered forms there are usually not more
than two chambers in each convolution, (a) Test unsegmented, plano-
spiraL Genus — Cornuspira, M. Sch. (Fig. 20). (b) Test piano-spiral, two
chambers to a convolution. Genera — Spiroloculina, d'Orb. (Fig. 21).
All the chambers exposed on the contour. Biloculina, d'Orb. (Figs. 22, a,
and 24). Chambers simple, only the last two chambers exposed on the

THE FORAMINIFERA 143

contour. Fabularia, Def. Similar, but chambers subdivided in the
interior. Sigmoilina (Planispirina, pars), Schlumb. (c) Three chambers
exposed on the contour of the test. Genus — Triloculina, d'Orb. (Figs.
22, 6, and 25). (d) Five chambers exposed on the contour of the test.
Genus — Quinqueloculina, d'Orb. (Fig. 23). (e) In the megalospheric form
the second chamber completely invests the megalosphere. Genus —
Adelosina, d'Orb. Chambers arranged on the quinqueloculine plan, or
(in A. polygonia, Schlumb., Fig 26), plano-spirally, three or four to a
convolution. (/) Earlier chambers quinqueloculine, later spiroloculine.
Genus — Massilina, Schl. (</) Miliolinidae trematophorae. Chambers with
inner as well as outer walls, and with sieve-like orifices. Eocene and two
recent spp. Genera — Idalina, M.-Ch. and Schlumb. Test biloculine in
later stages, and ultimately uniloculine ; chambers simple (Fig. 27).
Periloculina, M.-Ch. and Schlumb. Arrangement similar, but chambers
partially subdivided by ridges. Lacazina, M.-Ch. Uniloculine stage
assumed early in growth ; chambers subdivided by longitudinal rows of
pillars.

FAMILY 2. HAUERINIDAE. First formed part of test milioline or
Cornuspira-like, later with chambers in spiral or rectilinear arrangement,
aperture single. Genera — Ophthalmidium, Kiibl. Piano-spiral, Cornuspira-
like at first, later segmented (Fig. 41). Planispirina, Seg. Segmented.
Hauerina, d'Orb. Milioline (? quinqueloculine) at first, then piano-spiral.
Vertebralina, d'Orb. Piano-spiral at first, then linear. Articulina, d'Orb.
Milioline (tri- or quinque-loculine) at first, then linear (Fig. 28).

FAMILY 3. PENEROPLIDIDAE. Test piano-spiral, crozier- shaped, or
cyclical ; usually bilaterally symmetrical ; apertures many. Genera —
Peneroplis, Montfort. Chambers undivided, arranged plano-spirally
throughout, or the later ones rectilinear (Fig. 29). Orbiculina, Lam.
Chambers subdivided by secondary septa ; early segments equitant (Figs.
30-32). Orbitolites, Lam. Test discoidal, chambers subdivided into
chamber-lets ; early chambers not equitant ; arrangement at first piano-
spiral, then cyclical (Figs. 33-40). Meandropsina, M.-Ch.

FAMILY 4. ALVEOLINIDAE. Test spiral, elongated in the direction
of the axis of convolution. Chambers divided into chamberlets. Genus —
Alveolina, d'Orb. Test subglobular or fusiform.

FAMILY 5. KEBAMOSPHAERIDAE. Test spherical, chambers in con-
centric layers. Genus — Keramosphaera, Brady.

FAMILY 6. NUBECULAKIDAE. Test irregular, asymmetrical, usually
adherent. Genera — Sqiiamulina, Schultze. Test a single adherent
chamber. Nubecularia, Def. Test more or less spiral or adherent, often
encrusted with sand.

Calcituba polymorpha, Roboz, appears to be a degenerate form of the
Miliolidea.

ORDER 5. Textularidea.

Tests of the larger species arenaceous, either with or without a

perforated calcareous basis ; smaller forms hyaline and conspicuously

perforated. Chambers arranged in two or more alternating series, or
spiral, or confused ; often multiform.

144 THE FORAMINIFERA

FAMILY 1. TEXTULARIDAE. Typically bi- or tri-serial ; often bi-,
rarely tri-formed. Genera — Textularia, Def. Chambers in two rows,
alternating ; aperture an arched slit transverse to long axis of test at the
base of the inner wall of the final segment. Cuneolina, d'Orb. Ver-
neuilina, d'Orb. Triserial, with textularian aperture (Fig. 44, C). Tritaxia,
Keuss. Triserial, with a produced central aperture. Chrysalidina, d'Orb.
Triserial, with porous aperture. Bigenerina, d'Orb. Early chambers
textularian, later uniserial (Fig. 44, D). Pavonina, d'Orb. Arrangement
similar, but test fan-shaped and aperture porous. Spiroplecta, Ehrbg.
Early chambers piano-spiral, later textularian (Figs. 43 and 44, A-b).
Gaudryina, d'Orb. Early chambers triserial, later textularian. Valvu-
lina, d'Orb. Free or adherent, spiral, typically with three chambers in
each convolution. Clavulina, d'Orb. Early chambers triserial (valvuline),
later uniserial and rectilinear (Fig. 44, E).

FAMILY 2. BULIMINIDAE. Typically spiral ; weaker forms more or
less regularly biserial, aperture oblique, more or less comma -shaped.
Genera — Bulimina, d'Orb. Spiral, elongate, more or less tapering, often
triserial (Fig. 54). Virgulina, d'Orb. Much elongated, often biserial.
Bifarina, P. and J. Early chambers Bulimine or Virguline, later uniserial.
Bolivina, d'Orb. Biserial. Pleurostomella, Reuss.

FAMILY 3. CASSIDULINIDAE. Test a Textularia-like series of alter-
nating chambers, more or less coiled on itself in a piano-spiral manner.
Genera — Cassidulina, O'Orb. Ehrenbergia, Reuss.

ORDER 6. Chilostomellidea.

Test calcareous, finely perforate, polythalamous. Segments following
each other from the same end of the long axis, or alternately at the two
ends, or in cycles of three ; more or less embracing ; aperture a curved
slit at the end or margin of the final segment. Genera — Ellipsoidina,
Seg. Chilostomella, Reuss. Allomorphina, Reuss.

ORDER 7. Lagenidea.

Test calcareous, very finely perforated, monothalamous, or consisting
of a number of chambers joined in a straight, curved, spiral, alternating,
or (rarely) branching series. Aperture terminal, simple or radiate. No
canalicular skeleton or canal system.

FAMILY 1. LAGENIDAE. Test monothalamous. Genus — Lagena, Walker
and Boys (Fig. 46).

FAMILY 2. NODOSARIIDAE. Test polythalamous, straight, arcuate,
or plano-spiraL Genera — Nodosaria, Lam. Straight or curved, chambers
circular in transverse section, aperture central (Figs. 45, A and B). Lingu-
lina, d'Orb. Straight, chambers oval in section, aperture a fissure.
Frondicularia, Def. Compressed, segments V-shaped (Fig. 45, C). Ehab-
dogonium, Reuss. Straight or curved, triangular or quadrangular in
section. Marginulina, d'Orb. Elongated, circular in section, aperture
marginal. Vaginulina, d'Orb. Elongated, septation oblique, aperture
marginal. Bimulina, d'Orb. Cristellaria, Lamk. Piano-spiral in part, or

THE FORAMINIFERA 145

entirely (Fig. 47). Amphicoryne, Schlumb. Early chambers cristellarian,
later nodosarian. Allied are the fossil biformed genera Lingulinopis, Eeuss ;
Flabellina, d'Orb. ; Amphimorphina, Neugeb. ; and Dentalinopsis, Reuss.

FAMILY 3. POLYMORPHINIDAE. Chambers arranged spirally or
irregularly round the long axis, rarely biserial or alternate. Genera —
Polymorphina, d'Orb. Bi- or tri-serial, or irregularly spiral, aperture
radiate (Fig. 48). Dimorphina, d'Orb. Early chambers polymorphine,
later nodosarian. Uvigerina, d'Orb. More or less spiral, aperture pro-
duced, often tubular, and lipped. Sagrina, P. and J. Early chambers
uvigerine, later nodosarian.

FAMILY 4. RAMULINIDAE. Test irregular, branching. Genus — Ramu-
lina, R. Jones.

ORDER 8. G-lobigerinidea.

Test free, calcareous, perforate ; chambers few, inflated, arranged
spirally ; aperture single or multiple, conspicuous. No canalicular
skeleton or canal-system. All the larger species pelagic in habit. Genera
— Globigerina, d'Orb. Test coarsely perforated, trochoid, rotaliform or
symmetrically piano-spiral, pelagic specimens usually spinous (Fig. 49).
Orbulina, d'Orb. A spherical test with large and small perforations, beset
with spines, and containing a Globigerina-shelH. It is a late phase in
the life-history of some forms at any rate, of Globigerina (Fig. 49).
Hastigerina, Wy. Th. Regularly nautiloid and involute, armed with
long serrate spines, which are triangular in section, aperture large.
Pullenia, P. and J. Regularly or obliquely nautiloid and involute,
chambers only slightly ventricose, aperture a long curved slit, pores very
minute. Sphaeroidina, d'Orb. Chambers forming together a nearly
globular shell. Candeina, d'Orb. Trochoid, thin -walled, aperture con-
sisting of rows of pores.

ORDER 9. Rotalidea.

Test calcareous, perforate ; free or adherent ; typically spiral and
" rotaliform," i.e. coiled so that all the chambers are visible on the
" superior," " dorsal," or " apical " side, those of the last convolution only
on the " inferior," " basal," or " apertural side," sometimes one side being
convex, sometimes the other. Aberrant forms evolute, outspread, acervu-
line, or irregular. Some of the higher modifications with double
chamber-walls and canalicular skeleton.

FAMILY 1. SPIRILLINIDAE. Test spiral, non- septate. Genus —
Spirillina, Ehrbg. Complanate and piano-spiral, free or attached.

FAMILY 2. ROTALIDAE. Test rotaliform, rarely evolute, very rarely
irregular or acervuline. Genera — Patellina, Will. Test conical, with an
external layer of spirally arranged or annular chambers, subdivided into"
chamberlets, the interior of the cone filled either with hyaline shell-sub-
stance, or with chambers. Cymbalopora, Hag. More or less trochoid.
Early chambers spiral, later concentric, pelagic specimens with a large in-
flated chamber covering the base of the shell Discorbina, P. and J. Free
or adherent, rotaliform, trochoid or plano-convex, with either the superior
or the inferior (apertural) surface convex, somewhat coarsely porous,

10

146 THE FORAMINIFERA

aperture an arched slit at umbilical margin of last chamber. Planor-
bulina, d'Orb. Normally adherent, compressed or complanate ; chambers
very numerous, at first on spiral, later on cyclical plan, and each chamber
opening at the periphery ; walls coarsely porous. Truncatulina, d'Orb.
Free or adherent, rotaliform, the inferior face generally more convex
than the superior ; aperture a curved slit, near the superior (apical)
margin of the last chamber. Anomalina, P. and J. Like Truncatulina,
but more nearly plano-spiraL Carpenteria, Gray. Adherent, spiral,
convex, or monticular ; chamber.? few ; aperture at apex of final segment.
Rupertia, Wallich. Columnar, attached by a spreading base, chambers
numerous, spirally arranged, aperture at the basal end of terminal suture
of last segment. Pulvinulina, P. and J. Rotaliform, finely porous,
chambers few, with lines of secondary deposit over the sutures ; aperture
large, at the umbilical margin of the last segment. Rotalia, Lamk.
Rotaliform, finely porous, with secondary deposit over sutures or in
umbilicus ; aperture nearer the peripheral than the umbilical margin
of the last chamber ; larger spp., with interseptal canals. (Fig. 50.) Cal-
carina, d'Orb. Rotaliform, lenticular, with radiating spines at periphery ;
canalicular skeleton largely developed.

FAMILY 3. TINOPORIDAE. Test of irregularly massed chambers, the
early ones more or less distinctly on a spiral plan ; usually without
any general aperture. Genera — Tinoporus, Carp. Lenticular or sub-
spheroidal, with radiating marginal spines, early chambers arranged in
a plano-spiraL Gypsina, Carter. Free and spheroidal or attached and
spreading, coarsely perforated, no canal-system. Aphrosina, Carter. Poly-
trema, Risso. Test usually pink, at first rotaliform and free, then
adherent, encrusting or arborescent.

ORDER 10. Nummulitidea.

Test calcareous, finely tubulated, free, spiral, bilaterally symmetrical
(except Amphistegina), the higher forms with canalicular skeleton and
canal system.

FAMILY 1. FUSULINIDAE. Test fusiform or subglobular, chambers
extending from pole to pole, each convolution completely enclosing the
previous whorls. Genera — Fusulina, Fischer. Chambers entire. (Fig.
59.) Schwagerina, Moller. Chambers subdivided.

FAMILY 2. POLYSTOMELLIDAE. Test nautiloid. Genera — Nonionina,
d'Orb. Canalicular skeleton rudimentary or absent, aperture a simple
curved slit. Polystomella, Lamk. Canalicular skeleton more or less
fully developed ; aperture a V-shaped line of pores.

FAMILY 3. NUMMULITIDAE. Test lenticular or complanate ; a
canalicular skeleton and complex canal -system in the higher forms.
Genera — Archaediscus, Brady. Lenticular, consisting of a non-septate
tube irregularly coiled, embedded in finely tubulated envelope. Amphi-
steyina, d'Orb. Lenticular, inequilateral, chambers spirally arranged,
equitant, the alar prolongations simple on one side of the test, subdivided
on the other. Operculina, d'Orb. Piano-spiral, the whole of the con-
volutions exposed ; canal-system well developed. (Fig. 55.) Nummulites,
Lamk. Lenticular or complanate, piano-spiral, regular, chambers equitant

LITERATURE OF THE FORAMINIFERA 147

their alar prolongations enclosing the previous whorls ; a complex canal
system. (Figs. 5 and 6.) Assilina, d'Orb. Complanate, structure as in
Nummulites, but the alar prolongation of the chambers are thin, so that
the outline of the inner convolutions is visible. Heterostegina, d'Orb.
Resembles Operculina in plan, but the chambers subdivided into chamber-
lets, and equitant. (Fig. 56.) Cycloclypeus, Carp. Chambers usually in a
single layer, confined to the median plane of the test ; at first spiral,
then cyclical (Figs. 57 and 58). Orbitoides, d'Orb. Layers of flattened
chamberlets are disposed on either side of the chambers of the median
plane. Growth probably spiral before it becomes cyclical. Miogypsina,
Sacco. Early chambers spiral, eccentric.

LITERATURE REFERRED TO.

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148 LITERATURE OF THE FORAMINIFERA

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LITERATURE OF THE FORAMINIFERA 149

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47. Unters. iiber den Generationswecb.se! von Trichosphaerium sieboldi

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50. Note sur quelques Foraminiferes nouveaux ou peu connus du Golfe

de Gascoigne. Feuille des Jeunes Naturalistes, annee 13, p. 19.

51. Sur le Biloculina depressa au point de vue du dimorpbisme des

Foraminiferes. Assoc. Francaise, Rouen (1883), p. 520.

52. Note sur le genre Adelosina. Bull. Sqc. Zool. de France, t. xi.

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53. Note sur le genre Planispirina. Bull. Soc. Zool. de France, t. xii.

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(1890), p. 143.

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de France, t. iv. (1891), p. 155.

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France, t. xxvi. (1898), p. 336 ; see also t. xxvii. (1899), p. 463.

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61. Premiere note sur les Orbitoides. Bull. Soc. Geol. de France,

Ser. 4, t. i. (1901), p. 459.

62. Schwagcr, C. Article on Fossil Foraminifera in Biitschli's Protozoa (vide 6),

p. 242.

63. Semper, G. Reisebericht. Zeits. f. wiss. Zool. Bd. xiii. (1863), p. 562.

64. Schultze, M. Ueber den Organismus der Polythalamien. 1854.

64a. Schulze, F. E. Rhizopodenstudien, vi. Arch, fur mic. Anat. Bd. xiii.
(1877), p. 9.

65. Schubert, E. J. Ueber die Foraminiferen- "Gattung" Textularia Defr. u. ihre

Verwandtschaftsverhaltnisse. Verb. d. k. k. geol. Reichsanstalt, 1902,
No. 3, p. 80.

66. Sollas, W. J. On the Physical Characters of Calcareous and Siliceous

Sponge Spicules and other 'Structures. Proc. Royal Dublin Soc. N.S.
vol. iv. (1885), p. 374.

67. Verworn, M. Biologische Protisten-Studien. Zeits. fur wiss. Zoologie,

Bd. xlvi. (1888), p. 455.

THE PEOTOZOA (continued}

SECTION K. — THE SPOROZOA l

CLASS SPOEOZOA.

SUB-CLASS TELOSPORIDIA.

Order 1. Gregarinida.
„ 2. Coccidiidea.
,. 3. Haemosporidia.

SUB-CLASS NEOSPORIDIA.

Order 4. Myxosporidia.
„ 5. Sarcosporidia.

INCERTAE SEDIS.

Order 6. Haplosporidia.
,, 7. Serosporidia.
„ 8. Exosporidia.

INTRODUCTORY. — The Sporozoa are a group of exclusively para-
sitic Protozoa, of very widespread occurrence, infesting the
internal organs or tissues of animals belonging to almost all classes
and orders of coelomate Metazoa. There is perhaps no species of
annelid, mollusc, arthropod, or vertebrate which is not liable to
become the host of some kind of sporozoan parasite, at any rate
in certain localities, while many animals harbour several species of
these intruders at the same time. Moreover, in some cases, as,
for instance, that of the common earthworm, or the mealworm,2
scarcely an individual can be found which does not contain more
or fewer of its particular form of sporozoan parasite. Correlated
with their wide distribution, the Sporozoa exhibit the utmost
diversity of structural and developmental characters. As a

1 By E. A. Minchin, M.A., Professor of Zoology, University College, London.
2 The larva of the meal-beetle, Tenebrio molitor.

THE SPOROZOA

general, though by no means universal, rule, each species of
Sporozoon is parasitic on a particular species of host, or on a limited
number of allied species, and is usually confined to definite organs
or tissues of the host. In other words, the
various species of Sporozoa, like most internal
parasites, have acquired each an organisation in
harmony with certain special conditions of life,
and, except for a brief period of their developmental
cycle, they cannot exist apart from the very definite
and limited environment to which they are exclusively
adapted.

The Sporozoa also differ widely as regards the
effects they produce upon the animals which harbour
them. In many, perhaps in most, cases the general
health and vital activity of the host seems to be
quite unaffected, even when it contains great numbers
of the parasites. But in other cases Sporozoa pro-
duce dangerous or even fatal diseases, and may be the
cause of ravaging epidemics. Instances of this will be
found below, especially under the heading of the Myxo-
sporidia. It is sufficient to mention here the various
forms of malarial fever in man, now known to be caused
by sporozoan parasites of the order Haemosporidia. A
still more deadly human disease, namely cancer, has
also been referred to the agency of Sporozoa, but this
charge has not yet been brought home to them satis-
factorily.

Different species of Sporozoa vary between wide
limits as regards size, as well as in other characters.
From minute organisms, several of which can be con-
tained in a single blood-corpuscle, we find all grada-
tions of size up to creatures whose dimensions must
be regarded as very considerable, or even gigantic,
FIQ j in view of the fact that the sporozoan individual

Trophozoite (sporont) is> Kke other Protozoa, a single nucleated cell,
of Porospora gigantea, Many of the Gregarines are quite visible to the

(v. Ben.), x 150. a, nu- ™V & 1

cieus. (After van Bene- naked eye, and Porospora gigantea (v. Ben.) from

den, from Lankester.) ,-, , , . , • •, , r , ,,

the lobster attains a length of 16 mm., or two-
thirds of an inch (Fig. 1). In spite, however, of the extremest
diversity in size, appearance, organisation, and life- history, the
Sporozoa as a group possess certain very characteristic features in
common — peculiarities which are clearly in direct relation with
their habit of life as internal parasites.

In the first place, their nutriment is always of a fluid nature,
consisting of the juices of the host absorbed osmotically at the
surface of the body of the parasite, and none of the special organs

152 THE SPOROZOA

for ingesting or digesting solid food, so frequent in other Protozoa,
are ever found in this group. Many Sporozoa possess flagella
during certain phases of the life -cycle, and many exhibit the
power of executing amoeboid movement and emitting pseudopodia
during even the whole period of growth ; but in both cases the
flagella or pseudopodia are organs of locomotion and not of
nutrition, except perhaps in so far as the latter may contribute
to an increase of the absorptive surface of the body. More
usually all such locomotor organs are absent, and the body of
the parasite has a fixed form and definite contours, limited ex-
ternally by a cuticle of greater or less thickness, through which
food is absorbed by diffusion. Food - vacuoles or contractile
vacuoles are never found.

In the second place, the Sporozoa always possess the power of
rapid multiplication by sporulation that is to say, by the formation
of reproductive bodies or germs, each a fragment of the parent
body, in the form of a nucleated protoplasmic corpuscle, usually
very minute. These germs may serve for increasing the numbers
of the parasite within the same host, or may be the means of dis-
seminating the species and infecting other hosts. In the latter
case the germs are usually provided with protective envelopes
which enable them to leave the body of the host in which they were
produced and to endure for a season the vicissitudes of the outer
world. In some cases the protoplasmic germs are naked gymno-
spores, and all those derived from one parent are then enclosed in
a resistent cyst, formed by the parent previous to sporulation.
But in most cases the germs have their own special protective
envelopes, and are then termed chlamydospores, or more usually
spores simply. Within the spore-envelope a further multiplication
of the germs may take place, and a cyst enclosing all the spores de-
rived from a common parent may or may not be formed. Eesistent
spores of this kind are one of the most characteristic features
of this class, as the name Sporozoa implies. Only in the com-
paratively small number of cases in which infection is conveyed
from one host to another by an intermediate host, are protective
envelopes wanting.

The bulk of our knowledge of the Sporozoa is of extremely recent
date, and great advances have been made during the last ten years in
the investigation of these organisms and the elucidation of obscure points
in their life -history. Nevertheless, they did not entirely escape the
observation of the earlier naturalists, even so far back as the eighteenth
century. As might have been expected, attention was directed first to
the larger forms of Gregarines inhabiting Arthropods, especially insects,
and later to the characteristic spores, often to be found in vast numbers
in various animals.

The first notice of a Gregarine parasite is attributed to the famous

THE SPOROZOA 153

anatomist Eedi (1708), but his claims to this honour are very doubtful.1
Cavolini, however, in 17 87, described and figured an indubitable Gregarine
(Aggregata conformis (Dies.), fide Labbe) from the glandular appendages
of the stomach of Pachygrupsus marmoratus. He found conjugating
individuals, and believed each such pair to be a kind of tapeworm with
two segments. But the true discoverer of the group, in the scientific
sense, was Ldon Dufour, who, in his researches upon insect -anatomy,
became acquainted with, and described, numerous species of these parasites.
He regarded them as a peculiar group of worms, allied to Trematodes, to
which in 1828 he gave the generic name Gregarina. More species were
subsequently made known by other authors, and in 1839 Siebold published
an important work in which he described the nucleus accurately for the
first time, without, however, recognising the true nature of Gregarines,
which he also considered as worms, though he did not attribute to them
an alimentary canal, as had been done by one of his predecessors ! Siebold
also described the cysts and spores found associated with the Gregarines,
and though he did not discover the connection between them, his observa-
tions had the merit of drawing attention to the " pseudonavicellae " already
observed by Henle (1835) and others in the sperm-sacs of the earth-
worm.

Contemporaneously with Siebold's work appeared the investigations of
Hake upon the spores of the Coccidium of the rabbit, which, however, the
author regarded as pathological products of the tissues of the host itself.
In 1841 the celebrated Johannes M tiller described the spores of a number
of different Myxosporidia inhabiting various fishes, and termed these
organisms "psorosperms,"2 a name of very frequent occurrence in sporozoan
literature, applied to various kinds of spores. Miiller was, however, quite
in the dark as to the nature of his psorosperms, and considered them a
"living seminium morbi" comparable to spermatozoa. After Miiller
psorosperms were studied by many observers, and generally divided into
"egg-shaped psorosperms," e.g. Coccidia, and " fish - psorosperms " or
" Miiller's psorosperms," the spores of Myxosporidia. Their affinities
remained, however, uncertain for a very long time, and indeed the true
nature of " fish-psorosperms " has only been elucidated completely in the
most recent times. As long ago as 1842 Creplin compared psorosperms
to pseudonavicellae, and so laid the foundation of the " Gregarine-theory "
of the Myxosporidia. But this comparison was not universally accepted,
although supported by Leydig, Lieberkiihn, and other observers. Many
authors, on the other hand, regarded psorosperms as organisms of a
vegetable nature, allied to Diatoms.

A distinct epoch in our knowledge of the Sporozoa was made by
Kolliker, who in 1845 and 1848 not only greatly increased our know-
ledge of these parasites, and of their wide distribution and occurrence in
hosts of all classes, but further expressed and maintained for the first time
the opinion that Gregarines were unicellular organisms, which should be

1 See Biitschli, "Sporozoa" iu Bronn's Thierreich, i. p. 480, from whom most of
the historical facts here put together are taken. Labbe [4] identifies the Gregarine
figured by Redi as Aggregate/, praemorsa (Dies.).

2 Derived, according to Balbiani, from \f/<l>pa, mange, and ffirtpua, seed.

154 THE SPOROZOA

classed amongst Siebold's Protozoa, and identified Siebold's vesicle as the
cell-nucleus. His views were still further borne out by the important
observations of Stein, who in 1848 first demonstrated clearly the relation
of the pseudonavicellae to the reproduction of the Gregarines, which he
placed as a class Symphyta of the Protozoa. The views of Kolliker and
Stein have gradually obtained universal assent, especially after the demon-
stration by Lieberkiihn in 1855 of an amoeboid phase in the life-history,
and no one now doubts the position of Sporozoa amongst the Protozoa.
Nevertheless, for some years this view was energetically combated by
various authors, who could not bring themselves to regard the Gregarines
as adult, independent organisms. Chief amongst the opponents of the
Protozoan theory were Henle, Bruch, and Leydig, who believed that
Gregarines were in some way connected with the embryonic stages of
Nematodes or threadworms, and more particularly of the genus Filaria.
In the course of time, and with increase of knowledge, this theory died a
natural death, and it became evident that any associations of Gregarines
and Nematodes, or resemblances between them, were of a purely accidental
and superficial kind. Looking back, however, upon these controversies,
now only of historical interest, it is not a little remarkable that in very
recent times a curious nematode-like Sporozoon (Siedleckia nematoides,
Caull. and Mesn.) should have been discovered, which, had it been known
in the fifties, might have inclined the balance of zoological opinion strongly
over to the side of the Nematode theory.

A retrospect of the history of our knowledge of Sporozoa further
brings into prominence the fact that, as an obscure group of no obvious
practical importance, they did not for a long time appeal to the considera-
tion of the "common-sense" Englishman. Until comparatively recent
times, practically the only contributions to sporozoan literature in this
country were those of Lankester, who, besides other forms, discovered in
1872 the organism, parasitic in the blood of the frog, which at a subse-
quent date was named by him Drepanidium ranarum. This discovery,
and that of Laveran, who a few years later made known to science the
malarial parasites of human blood, laid the foundations of our knowledge
of the Haemosporidia, a group of such importance, from the practical
point of view, that they have been the cause of focussing the attention of
medical men, no less than of zoologists, in all countries upon the Sporozoa.
Indeed, so great is the interest which these parasites excite at the present
time, on account of their pathogenic properties in man and beast, that
now scarcely a month passes without the publication of some discovery
relating to them, and the study of the Sporozoa bids fair to assume in
the near future a position of importance scarcely secondary to that held
by the science of bacteriology.

The Structure and Life-history of a Typical Sporozoon. — As an
example of the Sporozoa and of the characteristic features of their
life-cycle, we select for detailed description the common Monocystis
agilis, Stein l (Fig. 2), a Gregarine parasitic in the sperm-sacs

1 With regard to the proper name of this species, there is a certain amount
of confusion and uncertainty, which is none the less regrettable because of so

THE SPOROZOA

155

(vesiculae seminales) of the earthworm (Lumbricus spp.). This
species is not only very easily obtained, but is also a very typical
example of the class ; hence in describing the various phases of its
life-history it will be possible at the same time to introduce and
define the terminology to which we shall adhere in the sequel

Fio. 2.

Trophozpites of Monocystis agilis. a and 6,
young individuals showing changes of body-
form due to contractility, c, an older in-
dividual, still enveloped in a coat of sperma-
tozoa, (a and 6 after Stein, c after Lieberkiihn,
from Lankester.)

Flo. 3.

Trophozoites of Monocyntis
magna, attached to the seminal
funnel of Lumbricus. a, young
individual; 6, goblet • shaped
epithelial cells of the seminal
funnel, in which the extremity
of the parasite is inserted.
(After Biitschli, from Lankes-
ter.)

for the corresponding
stages of other Sporo-

zoa. It should be understood, however, that the form
which can be selected as most typical of a group is not
necessarily the most primitive of its members. From the
type chosen we shall have to work backwards to simpler
forms, as well as forwards to more complex.

The earthworm is infested by various species or varieties
of Monocystis; according to Cu4iiot [13] by no less than seven
or eight species, of which four are stated to be of common
occurrence, namely, M. magna, A. Schmidt ; M. lumbrici (Henle)
( = M. agilis, Stein) ; M. pilosa, Cuenot ; and M. porrecta, A.
Schmidt. The specific distinctness of all these forms cannot
be unhesitatingly conceded, but at least two distinct species,
probably with several varieties, are generally recognised, and are
to be found in almost every worm, viz. M. magna and M. agilis.
The two species differ in size and in other specific details of
character. M. magna (Fig. 3) is the larger of the two, and
occurs attached by one extremity of the elongated body to
the epithelium of tbe seminal funnel, only quitting this situa-
tion at tbe period of conjugation, when it drops off into the
sperm-sac. M. agilis (Fig. 2) is found in the interior of the
clumps of developing spermatozoa, or floating freely in the sperm-
frequent occurrence in the zoological nomenclature of just the commonest or most
familiar forms of life, particularly amongst the Sporozoa. According to Labbe
[4] the species under consideration should be called Monocystis tenax (Dujardin) ;
according to Cuenot [13] its proper designation is M. lumbrici (Henle). We refer
to these authors for a discussion of these knotty questions, and retain here the name
most generally employed, in this country at least, for the species.

156 THE SPOROZOA

sacs. But all essential details of the life-history are quite similar in the
two species.

The earliest known stage of Monocystis agilis is a minute
protoplasmic body, with a distinct nucleus, lodged in one of
the " sperm-morulae " floating in the sperm-sac. As is well known,
each sperm-morula of the earthworm gives rise to a cluster of
spermatozoa, attached by their heads to a central residual mass
of protoplasm termed the " sporophore." The young Monocystis
is found within the sporophore and grows at its expense and at
that of the attached spermatozoa. This stage of the parasite,
during which it is absorbing nutriment from its host and growing
rapidly, may be termed the trophic stage, and each individual
parasite during this stage may be termed a trophozoite. The
parasite soon becomes elongated in one direction. It assumes
first an oval contour and becomes later more or less vermiform.
As it grows it destroys the sperm-cluster in which it is lodged,
and in later stages it is found enveloped in an adventitious coat
or fur composed of the tails of the degenerated spermatozoa,
giving the appearance of a ciliated covering, which is thrown off
in the final stages of growth (Figs. 2, c, and 4, a).

The full-grown trophozoite (Fig. 2) is still a single cell, with a
single nucleus. The body is limited by a distinct cuticle, within
which the protoplasm is differentiated into an external clear cortical
layer or ectoplasm, and an internal granular medullary layer or
endoplasm. The ectoplasm is the seat of contractility, and contains
in its deepest part a layer of fine contractile fibres, the so-called
myocyte-fibrillae. The endoplasm lodges the nucleus, and contains
numerous coarse granules representing nutriment held in reserve
for impending reproductive and developmental processes. The
nucleus is a clear spherical body, in the form of a vesicle
limited by a delicate membrane, containing fluid in which float
one or more nuclear corpuscles or karyosomes. Each karyosome is
a small globule, resembling in appearance the nucleolus of a
tissue-cell, but differing from it in containing a certain amount of
chromatin in its substance. The karyosomes usually have a
vacuolated structure. The trophozoite is actively motile, as the
specific name implies. In Monocystis the movements consist chiefly
of changes of form brought about by the contractility of the
myocyte-fibrillae, whereby the body may be bent or contracted
as a whole, or may exhibit ring-like constrictions in different
parts.

After the trophic stage, which is a period of purely vegetative
growth, the parasite enters upon the reproductive phase of its
life-history, a period in which two distinct events follow each
other ; first, the formation of gametes or conjugating individuals,
which pair with one another and unite to form zygotes ; secondly,

THE SPOROZOA

157

the formation from the zygotes of the Insistent spores, by which
the parasite is disseminated (see Fig. 29, p. 185).

The adult trophozoite, when it is ripe for reproduction, is
commonly known as a sporont, but may be better termed a
gametocyte, since it gives rise to the gametes. Two gametocytes
come together and become very closely apposed to form a spherical
body (Fig. 4), the two individuals remaining, however, perfectly

Fio. 4.

Association and encystation of
Monocystis magnet, a, a couple
attached to the ciliated epithelium
of the seminal funnel of the earth-
worm. The two gregarines are
covered by a furry coat of adherent
spermatozoa. 6, a couple detached
from the seminal funnel and en-
veloped by a common cyst-mem-
brane, s.f, seminal funnel ; n,
nucleus of the parasite ; c.m, double
cyst - membraiie. (After Cuenot.)
a, x37 ; 6, slightly less.

distinct from one another, each forming one hemisphere of the
common mass. This union of the two gametocytes must not be
confounded with the true conjugation : the two individuals are
merely in association ; they are keeping company, as it were, as
a preliminary to the formation of gametes. The two associated
gametocytes, which often exhibit a slow rotatory movement, now
become surrounded by a common envelope or cyst (Fig. 4, b, c.m),
secreted by them in two layers ; first a rigid external epicyst, then
a thin internal endocyst.1 Meanwhile important changes are going

1 According to Cecconi [11], in M. agilis the sporonts first become encysted
singly, and two such cysts then approach each other and join together. This prob-
ably applies only to the first signs of cyst-formation, as two completely encysted
gregarines can hardly be sufficiently motile to admit of their travelling towards one
another.

THE SPOROZOA

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FIG. 5.

Formation of the segmentation -
nucleus, and its subsequent division,
in sporonts of Monocystis. a, portion
of a section through two encysted
associated sporonts, separated by
their cuticular body-walls (c.iv). In
the lower half of the section is seen a
nucleus in which the karyosomes (kg)
are breaking up, while in the nuclear
sap near them a number of granules
of chromatin have appeared to form
the segmentation -nucleus (n.se.g).
Outside the nuclear membrane a
patch of archoplasm (arch) has appeared. In the upper half the archoplasm has divided
to form an achromatic spindle (ac.sp), in the middle of which are seen the chromatin granules
of the segmentation - nucleus ; two karyosomes are also seen, one showing a vacuolated
structure, b, section through one sporont of an associated couple in a cyst, showing the
segmentation-nucleus in the diaster stage. The karyokinetic spindle (ac.sp) stretches across
the whole body. The chromosomes (chr) form two groups, c, section through a couple of
encysted sporonts, showing in the lower one two resting nuclei preparing for division, and the
remains of a karyosome in the cytoplasm ; in the upper one two nuclei in the diaster stage, and
two karyosomes ; ep, epicyst ; en, endocyst. d, section through one sporont of a couple showing
seven resting nuclei (n), one dividing nucleus (nx), and two karyosomes (ky). (After Cuenot.)
a, x 1180 ; 6 and d, x 560 ; c, x 790.

THE SPOROZOA 159

on within the bodies of the gametocytes. In the nucleus of each
individual the karyosomes break up and become partially dis-
solved in the nuclear sap (Fig. 5, a-d, ky). At the same time a
number of chromosomes, in the form of grains or short filaments
of chromatin, appear grouped in a clump in the nuclear sap,1
constituting a renovated chromatic nucleus which may be termed
the segmentation-nucleus (Fig. 5, a, n.seg). At this point the
nuclear membrane disappears and the segmentation - nucleus
divides by karyokinesis, forming a nuclear spindle which
becomes elongated until it stretches across the whole body x)f
the gametocyte (Fig. 5, a and b, ac.sp). The two daughter-nuclei
divide again in their turn, and in this way repeated nuclear
divisions follow one another in each gametocyte ; but those in one
individual take place independently of those in the other, and
are not synchronous (Fig. 5, c). The karyosomes of the primitive
nucleus are left free in the cytoplasm and are slowly absorbed.
As the nuclei multiply, their size, and that of the karyokinetic
spindles, diminishes until it reaches a minimum (Fig. 5, b and d).
Nuclear division then ceases, and the minute nuclei travel to the
surface of the body. The cytoplasm of the gametocyte now
breaks up into a number of small masses each centred round
one of the tiny nuclei. Each of the small nucleated bodies thus
formed is commonly termed a sporoblast, but should be dis-
tinguished as a primary sporoblast, or better still, as a gamete
(Fig. 6, a). The protoplasm of the gametocyte is not entirely
used up to form the gametes, but a surplus of residual protoplasm
is left over, termed the cystal residuum (" reliquat kystal," " Rest-
korper "), which serves for the nutrition of the sporoblasts during
their further development. In the residuum are found also a
certain number of degenerated nuclei (Fig. 6, r.p, r.ri).

The next step is the conjugation of the gametes, which takes
place within the cyst. The cuticle which formed primitively the
body-wall of each gametocyte becomes dissolved, and the two
original individuals can no longer be distinguished, since the
gametes and other protoplasmic fragments derived from them
become intermingled. The gametes themselves now begin to
exhibit lively movements, the so-called " dance of the sporoblasts,"
which gradually cease as they conjugate in pairs. It is probable
that in each pair one gamete is derived from one of the two
parent gametocytes, and the other from the other, but it is by no
means certain that this is always the case. The two conjugating
gametes unite completely to form a single zygote or definitive sporoblast,

1 According to Cut-not the chromosomes are formed independently of the karyo-
somes, but it is more probable that, as in Coccidia (p. 216), their chromatin substance
is derived from a part of that which is stored up in the latter. The more recent
observations of Prowazek [25«] confirm this supposition.

i6o

THE SPOROZOA

in which the two nuclei also
fuse, the grains of chromatin
being intermingled, but re-
taining their distinctness
(Fig. 6, b, a*-*3).

Each sporoblast now
becomes a spore in the fol-
lowing way. The sporo-
blast becomes of oval form
and secretes on its surface
a tough membrane or sporo-
cyst, of a substance resem-
bling chitin (Fig. 6, c, Fig.
7, A, B). Within the
sporocyst the nucleus of
the sporoblast, or, as it
may now be termed, the
sporoplasm, divides into two,
then into four, and finally
into eight nuclei, by three
successive amitotic divi-
sions. The eight nuclei
take up an equatorial posi-
tion, and round each one
some of the protoplasm of
the spore becomes aggre-
gated, and segmented off as
a minute sickle-shaped germ
(Fig. 7, C} termed a sporosoite

Formation of gametes (primary sporo
blasts) and their conjugation in Mono-
cystis, seen in sections, re, portion of
a section through a sporont showing
the gametes (g) formed at the periphery
of the body round the residual proto-
plasm (r.p). Occasionally a gamete (g1)
may be formed deep in the residual
protoplasm, which contains also re-
sidual nuclei (r.n). b, the gametes
have fused in pairs to form zygotes,
in all of which the fusion of the cyto-
plasm is complete, but the nuclei are
either still separate (zi) or beginning
to unite (z2) or completely fused (z3).
The residual protoplasm (r.p) is break-
ing up into separate masses, in some
of which degenerating residual nuclei
(r.n) are to be found ; cy, cyst - en-
velope, c, the zygotes (definitive sporo-
blasts)have begun to secrete sporocysts
(sp.c), within which the sporoplasm
(sp.p) is becoming contracted ; a few
sporoblasts degenerate (sj/.W). Other
letters as before. (After Cuenot.)
X 1180.

THE SPOROZOA

161

("falciform body," " Sichelkeim "). The protoplasm of the sporo-
zoites is finely granular, and when they are formed, a surplus of
coarsely granular protoplasm is left over from the sporoplasm as
the sporal residuum ("reliquat sporal"). The fully-formed spore
has in Monocystis the form shown in Fig. 7, C ; it is more or < less
boat-shaped, and resembles a diatom of the genus Navicella, whence
is derived the name pseudonavicella, by which Gregarine spores have
long been known. The sporocyst is slightly thickened at each

FIG. 7.

Development of the spore of Mono-
cystis. A, oval sporoblast with single
nucleus (a). B, the sporoblast has
secreted the sporocyst at its surface,
and the sporoplasm within it has
become contracted and diminished
in volume. C, ripe spore with eight
sporozoites and residual protoplasm
(6). D, diagrammatic cross-section to
show the arrangement of the sporo-
zoites round the central residual pro-
toplasm. (After Biitschli, from
Lankester.)

pole, and within this very resistent and impervious envelope the
eight sporozoites are packed lengthways round the centrally placed
sporal residuum. During the formation of the spores the cystal
residuum is slowly absorbed, and the ripe cyst contains only a
great number of the pseudonavicellae, not arranged in any definite
pattern (Fig. 8).

The above account of the conjugation and spore - formation is that
given recently by Cuenot, whose researches confirm the discoveries of
Siedlecki with regard to an allied form Lankesteria ascidiae (Lank.), and
are in harmony with the still more recent account given by Leger [23]
for Stylorhynchus. Cuenot's description of the spore-formation and the
events antecedent to it is confirmed in all essential details by Cecconi [11]
and Prowazek [2 5 a]. Previous to Cue" not the reproduction of Monocystis
had only been studied by Wolters [29], whose description of the process
is very different. According to Wolters the association of the two full-
grown tropliozoites or sporonts within the cyst is a true conjugation,
similar in its details to that known in Actinophrys from the researches
of Schaudinn. Wolters describes the nucleus of each sporont as dividing
mitotically to form two nuclei, one of which is given off in a polar body,
while the other remains as a pronucleus. The two nuclei are then stated
to travel towards the septum formed by the apposition of the cuticular
body-walls of the two sporonts, and at one point the septum becomes
dissolved, permitting the fusion of the pronuclei into a single nucleus.
After a time the fusion -nucleus divides into two nuclei, which then
rapidly divide up to form numerous small nuclei, round which the proto-
plasm of the sporonts becomes segmented to form the sporoblasts. From
the sporoblasts the spores are formed as above described.

It is unfortunate that these statements of Wolters, which seem to be

ii

162

THE SPOROZOA

totally erroneous, have remained uncontraclicted for ten years, during
which time they have got into numerous text -books and have been
generally accepted and taught.

The spores of Monocystis do not appear to be able to develop
further in the earthworm, but require to be transferred to a
fresh host before they can germinate. How the infection is
effected has not yet been ascertained in the case of the type

FIG. 8.

Ripe cyst of Monocystis, showing the numerous spores (pseudonavicellae) scattered within
the cyst, without any cystal residuum present. (From Lankester.)

that has been selected for description, and the course of events
can only be conjectured by analogy from what is known to
take place in other Sporozoa. It is highly probable that the
spores pass to the exterior and are scattered broadcast in the
earth, and that they are then swallowed accidentally by an earth-
worm with its food, and so pass into its digestive tract. The
action of the digestive juices upon the spores has the effect of
causing the sporocysts to burst open, setting free the sporozoites,
which are actively motile and possess the power of boring their
way through cells and tissues. In this way the sporozoites prob-
ably traverse the wall of the earthworm's intestine and reach the
reproductive organs, where each one attacks a sperm-mother-cell

THE SPOROZOA 163

and there develops into the minute trophozoite which is formed
later within the sperm-morula. With this stage the life-cycle has
come round again to the point at which the description of it was
commenced.

A few points with regard to the life-cycle require brief further dis-
cussion. It has been suggested that the spores may sometimes germinate
in the host in which they are formed, and so increase the numbers of the
parasite within it But the improbability of this occurring is very
great, as was pointed out by Butschli, in view of the relatively small
number of parasites in the trophic stage which are met with, as com-
pared with the vast number of spores. Thus in a given earthworm there
will be found in the sperm -sacs perhaps a dozen trophozoites and as
many ripe cysts. Each of the latter contains, however, at a low esti-
mate about fifty spores, and each spore eight sporozoites. A single cyst
contains, therefore, about four hundred individuals, more or less, and if
it were a frequent occurrence for the spores to germinate in the same host,
the number of trophozoites in each earthworm might be expected to be
vastly greater than is usually the case.

Another question which may be raised is whether the Monocystis has
any method of multiplication during the trophic phase, that is to say, in
the period from sporozoite to sporont. It has sometimes been stated that
the trophozoites multiply by division during the earlier stages of growth.
From what is known of other Sporozoa, there is nothing inherently
improbable in this view, but it has not been proved satisfactorily
that such multiplication can take place in Monocystis, and the above-
mentioned paucity of the trophozoites is an argument against its
occurrence.

With regard to the passage of the spores to the exterior, precise
information is lacking as to how this is effected. In Sporozoa generally
we find one of two conditions. In some cases the spores are produced
in a position where they can leave the body by natural channels, as in
the numerous instances of sporozoan parasites lodged in the digestive
tract, when the cysts and spores are cast out with the faeces. In other
cases the spores cannot pass out by natural channels, and are set free
either by provoking suppuration or other organic disturbance, or by
the death and break-up of the host. In the case of the Monocystis of
the earthworm, the spores could only be discharged from the body, in the
ordinary course of events, by passing out of the sperm-sac with the sperm
at copulation. They would then be transferred to the spermathecae or
receptacula semiuis of another worm, and would pass ultimately into the
cocoon in which the eggs are laid ; but there is no record of their occur-
rence in either of these situations. It seems more probable that spores
are set free by the dissolution of their host. Very possibly birds or
some other of the numerous creatures which prey upon worms are the
agents by which the dissemination is effected. If a bird swallowed an
earthworm containing spores of Monocystis, from which very few worms
are free, the spores would probably pass unaltered thorough the bird's
digestive tract. Uninjured spores of Gregarines have been observed by

1 64 THE SPOROZOA

L. Pfeiffer in. the intestines and faeces of various birds.1 A parallel case
is that of the Coccidium infecting the centipede Lithobius, the spores of
which, if swallowed by another animal, such as a wood-louse, pass unaltered
through it (see p. 221). If this suggestion be correct, it is easy to under-
stand that any worm-eating bird would be continually scattering spores
of Monocystis on the ground, where they would wash down into the soil
and be swallowed very easily by worms again. There is, however, no
direct evidence bearing upon the mode of dissemination of the spores,
and the above suggestion must be regarded merely as a more or less
probable surmise.

When the spores have reached the digestive tract of their new host,
and the sporozoites have been liberated there, the question arises how
they reach the sperm-sacs. This problem, however difficult to solve, is
by no means one peculiar to the Monocystis of the earthworm. In many
other Sporozoa we have instances of parasites affecting some particular
organ, which invade the body in the first place from the digestive tract.
It must be assumed that the sporozoites have in some way the power of
selecting the particular organ they affect, and of migrating through the
body of the host in order to reach their specific habitat. Probably they
make use of vascular or lymphatic channels in order to arrive at their
destination.

General Characters of the Sporozoa. — From the above account
of Monocystis it is seen that the life-history of a typical Sporozoon
is a single cycle, which may be summed up in the following
way : 2 —

Sporozoite->-Trophozoite->-Gametocyte (Sporont) x n Gametes \ ,
Sporozoite->-Trophozoite->-Gametocy te (Sporont) x n Gametes / "•"

= n Zygotes (Sporoblasts)->-n Spores x 8)i Sporozoites.

The life-cycle may further be divided into three main periods.

First, the period of growth, during which the minute sporo-
zoite grows by absorption of nutriment from the host into the
sporont.

Secondly, the period of proliferation, accompanied by conjuga-
tion, and resulting in the formation of a large number of germs,
destined to spread the species.

Thirdly, the period of rest, during which the parasitic germs
pass out from the host into the outer world, to effect, if fortune
favour them, the passive infection of a new host.

In Sporozoa, considered generally, the life-history is similar in
the main to that described above, but exhibits, in different forms,
variations of every kind, in the direction either of greater or
of less complexity. The deviations from the selected type may

1 Fide Wasielewski [7], p. 26.

2 In this and in all subsequent formulae of sporozoan life-histories an arrow is
used to mean "becomes" or "grows into" ; the sign x to indicate a distinct cell-
generation, a multiplication of individuals of any kind ; and a bracket with the
sign + to denote the occurrence of zygosis or true conjugation and fusion of gametes.

THE SPOROZOA 165

be considered from two points of view, according as they affect
the characters (I.) of the individual stages or (II.) of the whole
life-cycle.

I. Each phase of the life-history may be varied or modified in
structural or other details, in accordance with the special environ-
ment and conditions of life to which a given species of these
parasites is adapted. The modifications that occur under this
head will receive detailed treatment in due course in the systematic
review of the orders, families, and genera of Sporozoa in the sequel,
but a few of the more important variations and simplifications may
be considered here. The trophozoites have commonly, as in
Monocystis, a definite body-form, limited by a cuticle ; but in many
forms the protoplasm is naked, and the body is amoeboid, and of
indefinite and changeable form. In Monocystis the gametes are not
differentiated and the conjugation is isogamous, but in other types
there may be anisogamous conjugation between sharply differentiated
male and female gametes. The greatest variation, however, is
seen in the spores. The number of the sporozoites is usually
eight in Gregarines, but may be greater or less in other types.
Hence the spores are distinguished as monozoic, dizoic, tetrazoic,
polyzoic, and so forth, according as they contain one, two, four, or
many sporozoites. In the monozoic condition there is no secondary
multiplication within the sporocyst, but each sporoblast simply
becomes a sporozoite. In many such cases the sporoblast secretes
no sporocyst, but becomes a naked gymnospore, resembling a free
sporozoite. These gymnospores may be formed within a resistent
cyst secreted round the sporonts, or the cyst may be entirely
absent. And further, the spore -formation may be preceded by
conjugation of gametes, or the spores may be produced asexually,
by the segmentation of a single sporont.

Hence in an ideally primitive type of sporozoan development,
the full-grown trophozoite or sporont simply breaks up, without
previous conjugation or encystment, into a number of naked
gymnospores, and each of them becomes a trophozoite which is
similar to its parent, and repeats the process in due course.

II. The plan and character of the life-cycle as a whole may
be greatly varied, and secondary modifications or complications of
various kinds introduced into it. The more important of these
variations will be briefly described.

(1) In Monocystis it has been seen that the period of growth
and the period of proliferation are sharply separated, the latter fol-
lowing upon the former. The same is the case in the whole order
Gregarinida, to which Monocystis belongs, and also in two other
orders, the Coccidiidea arid the Haemosporidia. On the other
hand, in the two orders known as Myxosporidia and Sarcosporidia,
spore-formation commences at an early stage in the growth of the

1 66 THE SPOROZOA

trophozoite, and spores are formed continually during the trophic
stage, so that there is no distinction between trophozoite and
sporont. Hence it has been proposed by Schaudinn to group the
Gregarinida, Coccidiidea, and Haemosporidia together as a sub-
class Telosporidia, contrasting them with a sub -class Neosporidia
comprising the Myxosporidia and Sarcosporidia. The Telosporidia
are Sporozoa in which the reproductive phases follow completion
and cessation of growth ; the Neosporidia are Sporozoa in which
growth and reproduction go on at the same time. It is probable
that this distinction indicates the deepest phylogenetic cleft in
this class of Protozoa.

(2) In Monocystis the whole life-history is a single cycle,
adapted entirely to spreading the infection amongst new hosts ;
it is, in fact, monogenetic. But in many other Sporozoa, belonging
to either of the two sub-classes recognised above, the parasite may
be capable of rapid multiplication within the body of its host,
which it thus completely overruns in many instances. In such
cases the life-cycle becomes digenetic, that is to say, it is differentiated
into two distinct generations or series of generations, the one endo-
genous or self-infective, the other exogenous or cross-infective. In
the endogenous generations the reproductive processes are usually
of a primitive type, taking place by binary or multiple fission, or
by a simple form of sporulation, known as schizogony, in which a
trophozoite, without encystation, breaks up into numerous gymno-
spores, implanted on a certain amount of residual protoplasm. The
sporulating individuals in this case are termed schizonts, and the
gymnospores are known as merozoites, to distinguish them from
the sporozoites of the exogenous generation. After a number of
endogenous generations, the parasite soon or later reproduces itself
by exogenous generation or sporogony, with the formation from
sporonts of resistent spores that can be disseminated outside the
body of the host. In monogenetic types the life-cycle consists of
sporogony alone.

(3) Considerable differences are seen in the manner in which
the infection of a new host is brought about. The vast majority
of Sporozoa appear to be disseminated passively, and the spores
are taken up directly, in an accidental manner, by another host of
the same kind as that from which they came. Should the spores
chance to be devoured by an animal of another species, they will
either be digested completely or will pass through its body un-
altered. Only in their proper host do the digestive juices have
the effect of liberating the sporozoites without harming them. In
some cases, however, especially amongst Sporozoa parasitic in the
blood, an intermediate host has been acquired, and is the agent
by which the parasite is disseminated. The best-known instance
of this is found in the malarial parasites, and is fully described

THE SPOROZOA 167

below. Here the endogenous generations multiply by schizogony
in the blood of a vertebrate host, until sporonts are formed, which
must be taken up by a blood-sucking insect, such as a mosquito,
in order to develop further. In the invertebrate host the exo-
genous generation takes place, and the sporonts give rise, by
sporogony after conjugation, to a number of gymnospores or
sporozoites, with which the vertebrate host is again inoculated.

In Sporozoa up to the present three modes of infection have
been observed. The first and commonest method may be termed
casual infection, where there is no intermediate host, and the
infection is acquired by swallowing spores accidentally with the
food. In the malarial parasites the infection is effected by the
inoculative method, through the agency of an intermediate host.
The third method is that of hereditary infection, a rare type, but
known in at least one instance, the silkworm-disease produced
by the myxosporidian parasite Glugea bombycis (see p. 290), and
possibly occurring also in the tick- fever parasites of cattle and
other mammals (p. 262). In the first of these two instances the
parasites penetrate the ovum and produce spores there, which
germinate and infect the next generation of the host. It is
possible that to these three modes a fourth should be added,
which may be termed the contagious method, seen in the parasites
which cause certain human skin-diseases (p. 238), but the sporozoan
nature of these bodies is by no means demonstrated with certainty.

Classification of the Sporozoa. — At least five well-established orders of
Sporozoa are generally recognised — the Gregarinida, Coccidiidea, Haemo-
sporidia, Myxosporidia, and Sarcosporidia. In addition, there are three
orders which are at present less well known and of very uncertain value
— the Haplosporidia, Serosporidia, and Exosporidia. The organisms
formerly known as Amoebosporidia must now be included in the
Gregarinida.

Many ways of grouping these orders into higher subdivisions or sub-
classes of the Sporozoa have been proposed. Labbe set up two sub-
classes : (1) Cytosporidia, in which the trophozoite is intracellular, either
throughout the trophic period or at least in the earlier stages of growth ;
(2) Histosporidia, in which the trophozoite is an intercellular tissue-
parasite. The Cytosporidia comprise the Gregarinida, Coccidiidea, and
Haemosporidia ; the Histosporidia include the Myxosporidia and Sarco-
sporidia. The grouping proposed is a natural one, but the distinctions
on which Labbe founded it have not the value which he attributed to
them, since the young stages of the Histosporidia are intracellular as
often as they are intercellular. Labbe now [4] subdivides the class into
Cytosporidia, defined as having "no spore, or a simple spore without
polar capsules," and Myxosporidia, having " the spore furnished with polar
capsules containing an evaginable filament," while the Sarcosporidia are
relegated to the Sporozoa incertae sedis.

1 68 THE SPOROZOA

Delage and Herouard [2] in their classification made use of the char-
acter of the sporozoite or protoplasmic germ within the spore, and divided
the class into (1) Rhabdogeniae, " with sporozoite of definite form, generally
falciform (arquee) " (Gregarinida, Coccidiidea, Haemosporidia, and Sarco-
sporidia) ; and (2) Amoebogeniae, " with amoeboid sporozoite " (Myxo-
sporidia). This classification has the disadvantage, however, of separating
the two nearly allied groups Myxosporidia and Sarcosporidia, and it has
not been followed by any subsequent writers.

Mesnil [6], making use of names invented by Metschnikoff, divides
the Sporozoa into Ectospora (Gregarinida, Coccidiidea, and Haemosporidia)
and Endospora (Myxosporidia, Sarcosporidia, and Haplosporidia). In the
Ectospora, the sporulation takes place at the close of the trophic period,
and the spore-mother-cells (sporoblasts) are formed at the periphery of
the sporont ; in the Endospora, spore-formation goes on during the growth
of the trophozoite, and the spore-mother-cells (pansporoblasts) are cut off
in the interior of the body (p. 283).

In the sequel the classification of Schaudinn into two groups, Telo-
sporidia and Neosporidia, as defined above (p. 166), is followed. It is seen
that, as compared with the classifications of Labbe and Mesnil, the dis-
tinction depends rather on the mode of defining the two subdivisions
than on essential differences in the plan of grouping the orders.

SYSTEMATIC EEVIEW OF THE SPOROZOA

SUB-CLASS TELOSPORIDIA.

Sporozoa in which the reproductive phase of the life-cycle is distinct from,
and follows after, the trophic phase.

ORDER 1. Gregarinida.

The Gregarinida, commonly known as Gregarines, are an order
of the Sporozoa remarkable for the degree to which structural
complexity of the individual, and adaptive specialisation of the
species, are carried. On the other hand, the life-cycle is usually
extremely simple. It might, in fact, be said, speaking generally,
that the Gregarines are the highest of the Sporozoa from the
standpoint of morphology, and the most differentiated from the
point of view of taxonomy, but are at the same time amongst the
simplest as regards reproductive phenomena. Their distinctive
characters are as follows : — The trophozoite commences its growth
typically as an intracellular parasite, usually, if not always, of an
epithelial cell ; never of a blood-corpuscle. It soon outgrows the
host-cell, and bulges from it, and finally drops out into an internal
cavity of the host, usually the digestive tract, but often the

THE SPOROZOA 169

haemocoele (blood-vessels or body-cavity), and sometimes the true
coelom. Here it continues to grow, absorbing nutriment from its
host, until it becomes a ripe, full-fed sporont. It then encysts,
with or without previous association with another of its kind, and
the process of spore-formation or sporogony commences. Sporo-
blasts are formed which usually secrete sporocysts and give rise
to spores, and within the spore-envelope the sporoplasm breaks up
into sporozoites, eight in number as a general rule. In a few rare
instances there is endogenous reproduction by schizogony, in
addition to the ordinary sporogony.

As lias been said above, the Gregarines were the earliest Sporozoa to
be observed and studied, on account of their large and conspicuous size.
The history of the group may be said to commence, for all practical
purposes, with the founding of the genus Gregarina by Dufour in 1828.
From that time onwards numerous observers, amongst whom Aime"
Schneider and Le"ger deserve special mention, have added to our know-
ledge of the abundance of genera and species of these parasites, or
have studied the details of their life -history and development.
Nevertheless, it is only in the most recent times, practically in the
new-born twentieth century, that the facts concerning the conjugative
processes have become accurately known, largely in consequence of
renewed investigations upon them stimulated by the interesting dis-
coveries made in other orders of Sporozoa.

Occurrence, Habitat, etc. — The Gregarines are confined for the
most part to invertebrate hosts, and have never yet been found in
any craniate vertebrate. The great majority of them lead blame-
less lives in the interiors of various arthropods, to which the
segmented forms comprised in the sub-order Cephalina are almost
confined. The unsegmented forms are found commonly, however,
in other groups also, especially in echinoderms, in annelids,
including gephyrea and hirudinea, and in tunicata. A few have
been recorded from turbellaria, nemertines, and enteropneusta,
and a doubtful species is known from Amphioxus. In molluscs,
however, they are almost unknown, the single recorded instance
being a species from the body -cavity of Pterotrachea. Thus the
Gregarines are to a large extent the opposite to the Coccidia in the
matter of the hosts they affect, the arthropods alone being ground
common to the two orders.

The infection of the host is probably effected in all cases by
way of the digestive tract, and the sporozoites, when liberated
there, proceed to attack the lining epithelium. In some cases
the sporozoite traverses the epithelium without stopping, passing
on into the haemocoele, as in Diplocystis of the cricket, or into
the coelom or one of its subdivisions, as in Monocystis. In other
cases it remains attached to an epithelial cell only by a small

170

THE SPOROZOA

portion of the body ; the intracellular stage or " Coccidian
phase" being practically suppressed. In other cases, again, a
large portion of the body, containing the nucleus,
is imbedded in the epithelial cell, while the rest
of the body projects freely from the host -cell.
But in typical cases the youngest trophozoites
are found as intracellular parasites, completely
enclosed by a cell of the epithelium, either of the
gut or some of its diverticula. In this situation
the parasite grows rapidly, and soon becomes
larger than the host-cell. The trophozoite then
falls out of the exhausted cell, usually passing
inwards towards the lumen of the gut, sometimes,
however, outwards into the vascular system or
body-cavity. Gregarines in the latter situation
are commonly termed "coelomic," without distin-
guishing whether the body-cavity in which they
lie is a true coelomic space or a part of the
haemocoele. Coelomic Gregarines, in the latter
sense, occur very frequently in insects (Fig. 9),
and in many cases a Gregarine may occupy
different situations at different periods of the
life of its host. It commonly happens that a
Gregarine inhabiting the digestive tract of an
insect -larva passes through the wall of the gut
at the metamorphosis, and so becomes a coelomic
Gregarine in the imago.

The young trophozoites have been shown to
have remarkable effects upon the cells in which
they are parasitic. The infected host-cell passes
through two successive phases — first one of
hypertrophy, then of atrophy. The facts have
been investigated by Laveran and Mesnil [16],
and still more recently by Siedlecki [28], in
The youngest trophozoites of Lankesteria ascidiae,
studied by Siedlecki, place themselves deep in the basal portion
of the epithelial cell, the region where the protoplasm of the cell
is least differentiated for secretion (Fig. 10, a). The nucleus
of the host-cell soon begins to appear swollen, its chromatin
network becomes loose and stains in a diffuse manner, and its
nucleolus increases greatly beyond the normal size, acquiring
irregular contours and often dividing into several parts. Hyper-
trophy of the nucleus is soon followed by that of the cytoplasm,
which appears clearer than in the adjacent cells, apparently as the
result of a sort of liquefaction. The protoplasm becomes difficult to
fix, and always stains much more feebly than the protoplasm of

Larva of Tipida ole-
racea, opened to show
the gut covered with
coelomieGregarine
cysts. (From Wasie-
lewski, after Leger.)

several species.

THE SPOROZOA

171

neighbouring cells. The Gregarine meanwhile is also increasing
in size, and its rate of growth exceeds that of the infected cell.
When it is large enough to fill the hypertrophied host -cell,
degeneration of the latter commences (Fig. 10, b). Its nucleus
shrinks, becomes crescent-shaped, and finally becomes a flattened
corpuscle which stains strongly and consists of debris of chromatin.
At the same time the cytoplasm is absorbed until it forms a thin
skin enclosing the Gregarine, and is finally cast off with it from
the epithelium. It is remarkable that in other cases a similar
series of changes may be provoked in the epithelial cell after the

u

FlO. 10.

Intracellular stages of Lankesteria aseidiae (Lank.) (par. dona intestirudis) in the intestinal
epithelium, a, young stages showing the hypertrophy of the epithelial cells induced by the
parasites at an early stage, ft, older stage showing very great hypertrophy of the epithelial cell,
with atrophy of its nucleus, ep, normal epithelial cell ; ep', hypertrophied epithelial cell con-
taining (G) the young Gregarine ; n, nucleus of normal cell ; »', nucleus of infected cell. (After
Siedlecki, x 750.)

Gregarine has grown out from it, and is attached to the cell only
by a minute point of contact (Fig. 11).

In many cases a Gregarine, after having been set free from an
epithelial cell which it has destroyed, may secondarily attach itself
again to the epithelium (Figg. 12 and 13). Although such second-
ary attachment may be exceedingly complicated, and may affect a
large number of epithelial cells, as in Pterocephalus (Fig. 12), never-
theless it only produces mechanical alterations in the cells, and never
has the marked effects which result from the primary attachment.

It is thus seen that the Gregarine destroys completely the cell in
which it is parasitic at the commencement of its career. Never-
theless Gregarines appear to be extremely innocuous to their hosts.
Since they do not reproduce themselves by schizogony, except in
a very few instances, they do not overrun their host in the way

172

THE SPOROZOA

that the Coccidia or Haemosporidia do. Though a given host often
contains a considerable number of Gregarines, it must be sup-
posed that they represent simply the batches of sporozoites derived
from several distinct infections. The epithelial cell that each
individual Gregarine has destroyed is not missed, and the injury

FIG. 11.

Effects produced on epithelial cells by the trophozoites of a
Gregarine (Pyxinia fremeli, Lav. et Mesn.) (par. Attagenus pellio,
larva). A, hypertrophy of the cell (first stage). B, atrophy (second
stage). Combined after figures by Laveran and Mesnil.

FIG. 12.

Portion of a section through the apparatus of fixation of a
Pterocephalus, showing root - like processes extending from the
Gregarine between the epithelial cells, which are not modified or
altered in any way, but appear to be under the influence of traction
exerted by the Gregarine. g, head of the Gregarine ; r, root-like
processes ; ep, epithelial cells. (After Siedlecki, x 500.)

FIG. 13.

Trophozpite of Larikes-
teria ascidiae (Lank.)
(par. dona intestinalis),
attached by an anterior
pseudopodium-like pro-
cess to an epithelial cell
(ep'), which is withered
and apparently destroyed
by it. ep, normal epithe-
lial cells. (After Sied-
lecki, x 500.)

is easily repaired. The nutriment that the Gregarines absorb in
the gut of the host seems to be a tax lightly borne. There is, in
short, no record of any pathological effects produced by these
parasites beyond those already noted in the case of the host-cell.

Morphology and Life-history. — Since a typical Gregarine has
already been described in Monocystis, it is only necessary to review

THE SPOROZOA

173

briefly the variations exhibited by this order as compared with
the type selected for description.

The body -form and external characters of the trophozoite
furnish sharp distinctions for classificatory purposes. The funda-
mental type of body-form may be described as a sphere or ovoid. In
many species this type of form is very nearly retained (Fig. 22),
especially in the non-motile coelomic forms, which often have a
great resemblance to ova. More usually, however, the body
becomes strongly elongated in one direction, a mode of growth
correlated either with attachment by one pole or with forward

j | ,- Epimerite.
) \

-Protomerite.

ir

Deutmnerite.

d

FIG. 14.

Scheme of development of a Gregarine from a sporozoite. a, free sporozoite ; 6 and c, stage
in the growth of the parasite within an epithelial cell ; <>, the Gregarine beginning to protrude
from the cell ; e, segmentation of the body and emigration outwards of the nucleus, the intra-
cellular portion of the body remaining as the epimerite ; /, adult Gregarine with three-
chambered body. (From Wasielewski, after Schneider.)

movement in a definite direction. In many cases the body is
extremely drawn out and attenuated, becoming vermiform in
character (Fig. 1).

In the sub-order Acephalina, of which Monocystis is an example,
the body remains simple and is not subdivided into different
regions, whatever its form. The Cephalina, however, are, with
few exceptions, septate, that is to say, the body is divided by
septa or partitions into distinct chambers or segments, usually
three in number. The septate condition is brought about in the
following way. The sporozoite penetrates an epithelial cell (Fig.
14, b) and grows within it into an oval body, which at an early
stage cannot be distinguished in any way from a young Mono-
cystid, or even from a Coccidian parasite (Fig. 1 4, c). Very soon,

174

THE SPOROZOA

however, the young trophozoite grows out from the host-cell, and
its nucleus travels out into that portion of the body which projects
from the cell (Fig. 14, d, e). The free extremity of the Gregarine
body continues to grow, while the intracellular portion becomes
cuticularised and forms simply an organ of fixation, commonly
called the epimerite. The extracellular Gregarine body becomes
now divided by a septum into two chambers, one smaller proximal
(i.e. nearer the host-cell and the epimerite), termed the protomerite^

Fio. 15.

Cephalont of Pyxinla
rubecula, Hamra. (par. Der-
'inestes spp.) still attached
by its epimerite to a de-
tached epithelial cell.
(From Wasielewski, after
Leger.) .

FIG. 16.

Corycdla armata, Leger (par. Gyrinus natator, larva),
o, cephalont ; 6, epimerite in the host-cell, magnified ;
c, sporont. (From Wasielewski, after L6ger.)

and one larger distal, termed the deutomerite, which usually contains
the nucleus (Fig. 14, /) ; abnormal forms are sometimes found,
however, in which the nucleus is lodged in the protomerite, owing
apparently to precocious formation of the septum, before the
nucleus had reached its distal position.

The young trophozoite in the Cephalina remains attached to
the host-cell for some time by its epimerite (Fig. 15). In this
condition it is known as a cephalont. Soon it becomes detached
and set free by a rupture of the junction between the epimerite
and protomerite (Fig. 16). The epimerite remains sticking in the

THE SPOROZOA

175

withered remains of the host-cell, and the Gregarine body, com-
posed of protomerite and deutomerite, is free in the gut, where
it continues its growth and further development. The free
Gregarines are commonly termed sporonts.

The epimerites of Gregarines show every variety of size, shape, and
pattern, and may be ornamented with hooks, spines, and other appendages
(Fig. 17). They function as organs of attachment, as has been said, and
probably also as organs of nutrition, since Laveran and Mesnil [16] have

FIG. 17.

Epimerites of various Gregarines. a, Grcgarinalonga (Leger), (par. Tipulasp., larva) ; b,Syda
inopinata, Leger (par. Audouinia sp.) ; c, Pileocephalus hcerii (Koll.), (par. Phryganea, larva) ;
d, Stylorhynchus longicollis, Stein (par. Blaps mortisaga) ; e, Beloides firmus (Leger), (par. Der-
mestes lardarius, larva); /, Cometoides crinitus (Leger), (par. Hydrobius sp., larva); g, Geneio-
rhynchus monnieri, A. Schn. (par. Libellula, larva); h, Echinomera hispida (A. Schn.), (par.
Lithobius forjicatus) • i, Pterocephalus nobilif, A. Schn. (par. Scolopendra spp.). (From
Wasielewski, after Leger.)

shown that they evoke changes in the host-cell which cannot be explained
as the result simply of mechanical irritation. The possession of an
epimerite is a feature which is used for classifying the Gregarines, and
the legion Eugregarinae is separated into the two sub-orders Cephalina and
Acephalina, according to the presence or absence of this appendage. As
a general rule the forms which possess an epimerite have the body
behind it divided into protomerite and deutomerite by a septum, and
have hence been termed Polycystida seu Septata (Lank.), while those
without an epimerite are also without a septum ; hence Monocystida
seu Haplocyta (Lank.). But in one family, Doliocystidae, Labbe, an
epimerite is present, and may attain a considerable size, as in Doliocystis
(Monocystis) aphroditae (E. R. L.), without any septum dividing the rest of

I76

THE SPOROZOA

the body (Fig. 1 9). It is purely a matter of definition whether these forms
be considered as Cephalina without a septum, or as Monocystida with an
epimerite. The Cephalina in which the body is non-septate are some-
times distinguished as Dicystida from those in which there is a distinct
protomerite and deutomerite (Tricystida). These terms are to be under-
stood, however, in a purely descriptive sense, and cannot be used for

FIG. 18.

Three specimens of Schneideria mucronata,
Leger (par. Bibio marei, larva), a, young
cephalont, attached to a host-cell, b, older
cephalont. c, sporont, showing traces of a
protomerite. (From Wasielewski, after Leger.) C

classificatory purposes, as there is 110 doubt that many dicystid species
are derived from tricystid forms secondarily, by obliteration of the
protomerite (Fig. 18). On the other hand, such forms as the Doliocystidae
(Fig. 19) and Selenidium (Fig. 46) appear to be truly and primitively
dicystid, and are to be regarded as intermediate forms transitional from
Acephalina to Cephalina.

In the aberrant forms comprising the legion Schizogregarinae, the
unsegmented body grows out into irregular processes, which give it an
amoeboid appearance, whence these forms obtained their older name,

THE SPOROZOA

177

Amoebosporidia. Eecent observations have shown, however, that these
processes are not pseudopodia, but are stiff outgrowths of the body, clothed

FIG. 19.

Doliocystis aphroditae
(Lank.) (par. Aphrodite
aculeata), a non- septate
Gregarine with a distinct
epimerite. (After Lan-
kester.)

Fio. 20.

Associations of Gonospora spfirsa, Leger, from the gut
of Glycera. (From Wasielewski, after Leger.)

by cuticle (Fig. 21), so that the name Amoebosporidia rests upon a mis-
conception and must be abolished. The genus Pterospora is also remarkable
for the possession of retractile processes, resembling tentacles (Fig. 37). ',

A curious feature of
Gregarines, and one which
has a marked influence
in many cases on their
external form and appear-
ance, is their tendency to
form associations during
the trophic period, a
peculiarity from which
the type-genus Gregarina
probably derives its name.
In Monocystis it has been /t.
seen that two individuals

come together when full- FIO. 21.

grown and become associ- ?ort.ion °tf » « c"°,n of a MaipigWan tubule of stops

mngica infested by Ophryocystis schneideri, showing three

ated to form a Cyst in individuals of the latter species (G), one of them with

T ,1 n two nuclei, attached by stiff processes (the pseudopodia

Common. In Other Ureg- Of Schneider) to the wall of the tubule, p, syncytial

irinaa acannin f inn mmr protoplasm of the tubule ; c, cilia lining it. (After Leger

armes association may £nd ifageiimuller, x isoo.)

take place at a much

earlier stage in the development of the individual (Fig. 20).

THE SPOROZOA

In the Diplocystis found in the body -cavity of the cricket,
young trophozoites become associated in couples almost immedi-
ately after leaving the host-cell, and, according to Cue"not, no
solitary individuals are to be found above a certain size, since
all the old maids die off. In Diplocystis major the two associates
retain their distinctness, but in Diplocystis minor each couple
becomes surrounded by a common membrane (Fig. 22). In
CystoUa holothwiae early association has still more far-reaching
results, since a fusion, complete except as regards the nuclei, of
the two trophozoites takes place, so that the appearance of a
single Gregarine with two nuclei is produced, with no trace of

FIG. 22.

Precocious association in Diplocystis
minor, Cuen., of the cricket. TO,
common membrane uniting the two
associates ; g, grains of albuminoid re-
serve material. (After Cuenot, x about
120.)

Fio. 23.

Adult trophozoite of Cystobia holo-
thuriae (Ant. Schn.) (par. Holothuria
tubulosa), showing the two nuclei,
derived from the fusion of two indi-
viduals, but not separated by any
septum. (After Minchin.)

any septum between them (Fig. 23). While in the cases
mentioned the association is undoubtedly a preliminary to the
conjugation of gametes, it is more difficult to interpret the
peculiar aggregations known as syzygies commonly seen in many
species, especially amongst Cephalina. Free Gregarine individuals
become attached to one another, the anterior extremity of one
adhering to the posterior end of the other (Fig. 24, a). Usually
such a syzygy consists of two individuals, but may be composed
of a chain of half-a-dozen or more (Fig. 24, c). The most anterior
individual is termed the primite, those behind it the satellites. The
latter are always individuals which have lost their epimerites, if
they belong to the Cephalina. The syzygy does not necessarily
take the form of a simple chain. Two satellites may be attached
side by side to the hinder end of the individual, primite or satellite,
in front of them (Fig. 24, b). In some cases the individuals com-
posing a syzygy are loosely attached and easily separated from
one another, and the members of it are not modified in any way.
In other cases the association is more intimate, and the satellite

THE SPOROZOA

179

or satellites may become modified in structure. In segmented

forms this alteration affects chiefly the protomerite, which may be

reduced or even absent. Thus in the genus Di'lymophyes syzygies

of two individuals are

formed in which the

satellite loses its

protomerite entirely,

so that the resulting

combination looks like

a three - chambered

Gregarine Avith two

nuclei (Fig. 25, a).

Although in many
cases the syzygies
appear to be tem-
porary attachments
which have no con-
nection with the sub-
sequent reproductive
phenomena, it is prob-
able that as a general
rule they represent
associations of indi-
viduals destined to
form conjugating
gametes as described
for Monocystis, especi-
ally in those cases
where the union of
primite and satellites
is an intimate one, as in Didymophyes and others. Having regard
to the manner in which conjugation takes place, there is no reason
why any number of sporonts or gametocytes should not come to-
gether to form gametes within a common cyst, and the presence
in a cyst of more than two sporonts appears to be of frequent
occurrence in some species.

The body of a Gregarine trophozoite always consists of cuticle,
ectoplasm, and endoplasm containing a nucleus, but each of these
parts are subject to considerable variation in structure.

The cuticle or epicyte is a membrane secreted by the ectoplasm,
usually of some thickness, and appearing doubly contoured hi
optical section (Fig. 26, c). Sometimes it can be broken up into
fine vertical lamellae corresponding to the ridges presently to be
described on the external surface. As has been said above, the
cuticle is often produced into hooks or spines or other organs of
fixation, especially on the epimerite. On the other hand, all such

Fio. 24.

a, Eirmocystis ventricosa, Leger (par. Tipula
spp.). b and c, E. pdymorplw., Leger (par. Lim-
nobia, larva). Associations of two, three, and
five Gregarines. p, primite ; s, satellites. (From
Wasielewski, after Leger.)

i8o

THE SPOROZOA

processes may be wanting entirely. The surface of the cuticle is
not smooth, however, but has a delicately ribbed or fluted
structure, producing fine striations which run in a meridional
direction from pole to pole. As a rule there are no openings or

visible pores of any kind in
the cuticle, but, according
^ to Siedlecki, a pore exists

at the anterior end of Lan-
^: kesteria ascidiae, from which
is protruded a minute
pseudopodium-like process
which serves for the
secondary attachment of
the trophozoite to an intes-
tinal cell of the host, and
-<& pores are stated to exist in
the longitudinal furrows of
the cuticle, as described
below.

The ectoplasm is a
clear, hyaline layer of
tougher protoplasm which
in the motionless forms
shows no special differen-
tiation. But in most
Gregarines, correlated with
the power of active move-

Trophozoites of Didymophyts. a,D.paradoxa,8tein ment, the deeper layer of

(par. Geotrupes stercorarius), two associated sporonts ; tV.0 or>tr>r»laem r>nntain<5 a

in the satellite the protomerite has disappeared. 6, ttle ectoplasm contains a

D. gigantea, Stein (par. Oryctes nasicornis), cephalont. system of contractile fibrils,
P. primite ; S satellite ; ep, epimerite ; mi. proto- -, . «> j

merite ; de, deutomerite ; n, nucleus. marking Ott a deeper

myocyte from a more super-
ficial sarcocyte layer of the ectoplasm (Fig. 26, m.f, sc). The sarcocyte
is prolonged inwards to form the septum separating protomerite
and deutomerite, when this division is found. The fibrils of the
myocyte (Figg. 26, m.f, and 27) run in a more or less circular
direction, with numerous oblique junctions and anastomoses, so
that the system as a whole is more or less net-like.

The movements of Gregarines are often very active, though
some forms appear perfectly motionless. Two kinds of move-
ments are commonly seen. In the first place, the body manifests
contractions of various kinds, without changing its place as a
whole. It may bend and straighten again, or may exhibit ring-like
constrictions which pass down the body in a manner resembling
peristaltic movement. The latter is a very characteristic form of
activity, and resembles greatly the " metabolic " form-changes seen

FlG 25

THE SPOROZOA

181

in many Flagellata, such as Euglena, for which reason these move-
ments were termed by Lankester " euglenoid." In the second
place, many Gregarines possess the power of gliding forward at a
great pace without any noticeable change of form, and without
any apparent mechanism for producing their rapid progression.

The contractions and euglenoid movements of the Gregarine
body are sufficiently accounted for by the myocyte-fibrillae, if the
latter be assumed to be endowed with a power of contractility

similar in its action to that of
ordinary muscle-fibrils. But the
gliding movements of Gregarines
have always been a great puzzle.

FIG. 26.

Longitudinal section of a Gregarine
in the region of the septum between
protoraerite and deutomerite, semi-
diagrammatic. Pr, protomerite ; De,
deutomerite; s, septum; en, endo-
plnsm ; sc, sarcocyte ; c, cuticle ; ?«./,
fibrils of the myocyte ; g, gelatinous
layer between sarcocyte and cuticle.
(After Schewiakoff, x 2000 diameters.)

Fio. 27.

Gregarina munierl (A. Schn.),
(par. Timarcha tembricosa), show-
ing the network of myocyte
tibrillae. (From Lankester.)

The first satisfactory attempt at an explanation was given by
Schewiakoff [26], who accounted for the forward progression by
the extrusion of gelatinous fibres from the hinder end of the body.
The fibres in question are derived from a clear homogeneous layer
lying between the cuticle and the sarcocyte, and pass out
from the body through minute slit-like pores in the furrows be-
tween the ridges of the cuticle ; they then run backwards in the
furrow towards the posterior end of the body, becoming stiffened
by the action of the surrounding medium, and project free from
the hinder end of the animal. The numerous threads thus
produced form a hollow cylinder which by its continued growth
and elongation pushes the Gregarine forward. Schewiakoffs
explanation has met with general acceptance, but very recently it
has been criticised by Crawley [12]. This author confirms the
extrusion of a gelatinous substance, but denies that it is the cause
or agency of progression, or could possibly be so in many cases,
especially in the elongated serpent-like forms, such as Porospora

1 82 THE SPOROZOA

giganlea, for example (Fig. 1). He attributes the forward pro-
gression to transverse movements of the body-surface, produced by
the myocy te layer, and manifesting themselves " as a shifting of
the cuticular striations in a direction at right angles to the long
axis of the animal." A muscular impulse of this kind, starting
anteriorly, passes along the body towards the hinder end, and
causes differences in the contact of the body with surrounding
objects. The wave of disturbance travelling along the surface of
the body brings about a movement of the Gregarine in a direction
opposite to that in which the impulse travels, and tends also to
cause a swinging movement of the body from side to side, which,
according to Crawley, can be observed very frequently in the
forward progression, especially when the Gregarine encounters an
obstacle in its path. Crawley thus refers the forward movement
to the contractility of the myocyte, and points out that "in
general, throughout the Sporozoa, the possession of muscle -fibres
and the power of moving from place to place go hand in hand, while
the forms which are not known to move lack muscular elements."

The endoplasm, the nutritive layer of the body, is of a more
fluid nature than the ectoplasm, but does not exhibit any of the
flowing movements often seen in other Protozoa. It is always
crammed with great numbers of granular enclosures, representing
reserve nutriment stored up for the reproductive period of the
life-history. It is rare for the endoplasm to be vacuolated. The
granules increase in number as the animal grows, and render the
adult trophozoites very opaque, especially when they attain to a
large size. The most abundant and largest kind of granules are
the paraglycogen spherules, always present and sometimes attain-
ing a diameter of 10 p.. They consist of a substance allied to
starch and glycogen, and are characterised by the following
reactions : Iodine tinges them brown, changing into violet on
addition of dilute sulphuric acid ; they are not dissolved by pure
acetic acid, weak mineral acids, alcohol, or ether ; but they are
soluble in dilute solution of potassium carbonate and in con-
centrated mineral acids. Other sorts of granules may be found in
various Gregarines, but do not occur universally in all species.
Such are the so-called carminophilous granules, of irregular form,
and composed apparently of an albuminoid substance which is
stained red by picrocarmine and acetocarmine, yellow by iodine ;
"pyxinin" granules, characteristic of the genus Pyxinia; fat-globules;
and occasionally protein crystals and other more or less enigmatic
enclosures.

The nucleus is always single, with the apparent exceptions due
to precocious association already mentioned (Fig. 23). It has the
form of a large spherical vesicle surrounded by a very distinct
membrane, and appears in life as a clear space in the opaque,

THE SPOROZOA 183

granular endoplasm. Within the membrane is a fluid nuclear
sap in which float one or more karyosomes, held in place by a
delicate nuclear reticulurn. Each karyosome is usually a spherical
body of vacuolated structure, as described for Monocystis. Some-
times the karyosome is drawn out and band-like (Fig. 44) or beaded.
As a general rule, however, the nuclei of Gregarines exhibit a
monotonous uniformity of structure and appearance.

The reproductive phase of the life-history is usually initiated,
as has been said, by the association of two or more sporonts, but
not infrequently a single Gregarine may become encysted by
itself, without pairing with another. In this case the sporont
breaks up into sporoblasts at once, a fact which may be expressed
in another way by saying that the gametes develop without
conjugation into spores, a proceeding which may be compared to
parthenogenesis. In such cases the spores are smaller than those
produced from zygotes.

The cyst is a structureless membrane secreted by the associated
sporonts. Its function is to afford protection to the reproductive
phases, and when once it is fully formed, subsequent develop-
ment can proceed outside the body of the host. The cyst-wall
consists commonly of a gelatinous outer layer, often of considerable
thickness and showing concentric striations termed the epicyst, and
a tough inner membrane, the endocyst. Some interesting mechan-
isms are found which have as their object the facilitation of the
escape of the spores from the cyst. In the majority of cases
the cysts dehisce by rupture of their walls, brought about by
swelling of their contents, and in particular of the residual proto-
plasm, or by contraction and shrinkage of the cyst-wall, or by
both causes combined. In other cases the residual protoplasm,
after the sporoblasts are separated off from it, undergoes further
development to produce a special mechanism. In the families
Dactylophoridae and Slylorhynchidae, the residual protoplasm forms
a compact mass which becomes surrounded by a membrane and
gives rise to a structure termed a pseudocyst, which gradually
swells until the true cyst-wall is burst asunder. In several genera
of Gregarinidae ( = Clepsydrinidae auct.) the cysts are remarkable for
the possession of sporoducts (Figg. 28 and 42), long tubular out-
growths through which the spores can pass out to the exterior.
These ducts are also formed from the residual protoplasm, which
take up a peripheral situation within the cyst, surrounding the more
centrally placed spores. It then secretes a membrane immediately
internal to the cyst-wall, and also gives rise to a variable number
of tubes, usually six or eight, but sometimes only one, which at
their first formation run inwards from the periphery of the cyst,
but later become everted to form the sporoduct.

The conjugation, so far as it has been observed, conforms to

1 84

THE SPOROZOA

the type described above for Monocystis, or takes place in a manner
easily deducible from it (Fig. 29). In Monocystis, Lankesteria,
Diplocystis, etc., there is perfect isogamy ; the conjugating gametes
are not distinguishable from one another, and do not fall into
two classes. In the Cephalina, on the other hand, anisogamy
of a highly differentiated type appears to prevail. In Stylo-
rhynchus L6ger [23] has recently described anisogamous conjugation

FIG. 28.

Cyst of Gregarina laucourwtensis (A. Schn.) (par
Parnus sp.) with a single, very elongated sporo-
duct. (From Wasielewski, after Aime Schneider.)

of a very interesting type. Two sporonts associate and become
encysted together : one of them gives rise to motile active gametes
termed male, the other to non-motile passive gametes termed
female. The sporonts themselves, therefore, may be considered
to be potentially male and female. Each sporont occupies one-
half of the cyst, so that a male and a female chamber can be
distinguished. Each sporont breaks up into a number of primary
sporoblasts or gametes, and at first the gametes formed in each
chamber are simply little protoplasmic spheres (Fig. 30, a), as in

THE SPOROZOA

185

Monocystis, but soon become differentiated. Those in the female
chamber are smaller (about 7'5 /x in diameter), without much
reserve material, and do not acquire any further structural
peculiarities (Fig. 30, e). Those in the male chamber are larger
and have more reserve material, and develop into motile gametes
with the following structure (Fig. 30, b, c, d). The body is fusi-
form or cylindrical, about 13 /x, in length, with an anterior clear

e.

PIG. 29.

Schematic figures of conjugation and spore-formation in Gregarines, after Calkins, modified ;
the details of nuclear structure and division copied from Siedlecki's figures of Lankesteria
ascidiae (E. R. L.). a, union of two sporonts in a common cyst. 6, division of the nucleus of
each sporont, showing various stages of division by mitosis, with very distinct centrosomes
and without loss of the nuclear membrane. Fragments of the karyosomes are also seen, one on
the left, two on the right, c, commencing formation of gametes. The very numerous minute,
irregularly-shaped nuclei place themselves at the surface, and become segmented off, as seen
on the lower side of the sporont on the right. (In iMnkesteria ascMiae at this stage the sporonts
become very irregular in shape and drawn out in various directions.) rf, Stages in the con-
jugation of the gametes. In the left upper quadrant of the figure are seen separate gametes ;
in the left lower quadrant the gametes are seen uniting in pairs ; the right lower quadrant
shows the fusion of the nuclei ; and in the right upper quadrant are seen complete zygotes or
definitive sporoblasts. e, Stages in the division of the nuclei of the sporoblasts, which at the
same time assume an oval form. The division of the nucleus takes place by the direct method
into two, four, and eight small nuclei. /, cyst with ripe spores, each of which contains eight
sporozoites derived from the eight nuclei of the sporoblast. Two spores are seen in cross-
section.

and a posterior granular extremity. The anterior end is prolonged
into a rostrum terminating in two little horn-like processes. The
posterior end bears a flagellum about 27 p. in length. The nucleus
is at the anterior pole of the body and consists of chromosomes
not enveloped in any membrane. The flagellum is continued from
the base forward through the body of the gamete as a delicate

1 86

THE SPOROZOA

axial filament which terminates in a deeply staining granule
placed just behind the nucleus. The male gametes become free
within the cyst and penetrate the female chamber, the rostrum
being directed in front. They each seek out a passive female
gamete and unite with it, often when still incompletely developed

FIG. 30.

Development of the gametes, and fertilisation, in Stylorhynchus longicollis. Stein (par. Blaps
mortisaga). a, undifferentiated gamete, still attached to the body of the parent gametocyte.
6, c, d, stages in the evolution of the motile male gamete ; the body elongates and becomes
prolonged posteriorly into a vibratile caudal filament, the nucleus being placed at the anterior
end, from which a short rostrum grows out ; from the distinct centrosome an axial filament is
prolonged through the body as far as the caudal filament, which appears to be a continuation
of the axial filament ; a prolongation of the axial filament in the opposite direction runs round
the nucleus and forms the axis of the rostrum (Leger). The fully mature gamete, d (" sperma-
tozoid," Leger), has the nucleus very condensed and the axial thread doubled, both in the
body and in the rostrum ; but as a rule the conjugation is hastened and takes place when the
male gamete is in the still immature stage shown in c ("spermatid" of Leger). e, mature
female gamete, only differing from a in the loss of the stalk attaching it to the parent body.
/, a "spermatid" conjugating with a female gamete, g, later stage of the conjugation; the
protoplasm of the two gametes has fused into a spherical mass and the nuclei are fusing. K,
zygote (sporoblast), with single nucleus, i, spore, with spore-membrane and single nucleus
preparing for division. (After Leger, x 1900.)

(Fig. 30, /). The flagellum drops off, but the bodies and nuclei of
the gametes fuse and the zygote forms a spore in the usual way
(Fig. 30, g, h, i). The conjugation occurring here is remarkable
in that the gametes are the opposite, in some points of their
equipment, to the general type of differentiation in anisogamy,
since the active male element is as large or larger than the passive
female, and as well provided with reserve material. In Pterocephalus,

THE SPOROZOA

187

on the other hand, Leger and Duboscq [24] have described conjuga-
tion between gametes differentiated in a manner more in accord-
ance with accustomed types of anisogamy. The gametes formed
in the female chamber resemble telolecithal ova, having the
nucleus situated in a patch of formative protoplasm at one pole,
while the rest of the cell is occupied by coarse vitelline granules.
The male gametes, on the contrary, are very minute, like those

Fio. 31.

Stages in the life-history of Ophryocystis bUtseMii, A. Schn (par. Naps mortisaga). a, large
multinucleate trophozoite with pseudopodiuni-like processes. 6, small trophozoite with one
nucleus, produced by the dividing up of a large individual, c, d, e, association and encystraent
of two sporonts. f-h, division and diminution of nuclei, i, single spore formed from the
zygote, with two residual nuclei in each half of the cyst, j, cyst with single spore and two
masses of residual protoplasm, k, ripe cyst with epicyst formed in numerous separate layers
and endocyst enclosing the single spore and the remnants of the residual protoplasm. (From
Wasielewski, after A. Schneider.)

of Coccidia, and consist almost entirely of chromatin substance,
nearly the whole protoplasmic body of the male gametocyte being
left behind in the male chamber as residual protoplasm, from
which the pseudocyst (see above, p. 183) is formed. The body of
each microgamete is described as being filamentous, 5 or 6 /*
in length, with a refringent rostrum anteriorly and a rlagellum,

i88

THE SPOROZOA

about double the length of the body, posteriorly, and as bearing
an undulating membrane which runs in a loose spiral from the
rostrum to the base of the flagellum. The microgametes fertilise
the " ova " in the usual way.

Another and interesting variation in the type of conjugation
has been described by L6ger [21] in the genus Ophryocystis of the
Schizogregarinae. Here perfect isogamy obtains, combined with
reduction of the gametes. The sporonts become encysted to-
gether, separated at first by a septum (Fig. 31, c-/). In each the
nucleus divides into two, and one daughter nucleus degenerates
(Fig. 31, g). The remaining nucleus divides again, and again one
daughter nucleus degenerates (Fig. 31, h}. The survivor is the
pronucleus and represents one -fourth of the nucleus of the
sporont. The protoplasm of the sporont condenses round it to
form a single gamete, leaving a large quantity of residual proto-
plasm containing the degenerating nuclei. The two gametes
derived in this way, each from one of the original sporonts, fuse,
the septum becoming absorbed. Thus in each cyst is formed a
single zygote (Fig. 31, i, j), which develops into the single
spore, containing when ripe the usual eight sporozoites. Some-
times, however, the septum is not absorbed, and each gamete
then develops parthenogenetically, so that the cyst contains two
small spores instead of a single large one. It is evident that this
condition is to be derived from that in Monocystis by reduction and
degeneration of all the gametes formed from each gametocyte except
one. In the allied genus Schisocystis numerous gametes are formed
from each sporont, and conjugate after the manner of Monocystis.
The spores of Gregarines are either naked gymnospores

or chlamydospores, invested
by a tough envelope. The
former condition is uncommon,
but is found in two genera of
Cephalina. In the first of
these, the genus Aggregate,
Frenzel, the gymnospores or
sporozoites are scattered in
the cyst round several residual
masses of protoplasm, giving
a certain resemblance to the
cysts of the malarial parasites
formed in the stomach of the

tteres passing through a eoelomic cyst of Aggregaia niOSQuitO (Fig. 32). In the
coelomica, Leger. The numerous sporozoites (s) 11

are arranged radially round masses of residual SCCOnd, the genUS Jrorospord, A.

protoplasm (r.p). cy, cyst-wall; ep, intestinal o_i.n crkArr>lYlaefo oro Wmorl

epithelium. (After Leger, x 180.) fecnn., sporoblasts are lormed,

each of which gives rise to very
numerous sporozoites grouped round a central mass of protoplasm,

FIG. 32.
Portion of a section of the intestine of Pinno-

THE SPOROZOA

189

and each such cluster of sporozoites resembles to a certain extent
an ordinary Gregarine spore, but has no enveloping membrane or
sporocyst (Fig. 41). Aggregates and Porospora are grouped together
as a tribe Gymnosporea in distinction to the ordinary Gregarines,
the Angiosporea, in which a chlamydospore is formed. The proto-
plasm of the sporonts may, in some cases, be entirely used up to
form sporoblasts, in which the sporulation is said to be complete,
but more often it is incomplete, with a more or less considerable
mass of residual protoplasm.

The typical Gregarine spore contains eight sporozoites, and is
therefore said to be octozoic, but exceptionally only four sporozoites
are formed, as in Selenidium, hence tetrazoic. The sporozoites are
grouped in very various ways round a granular mass of residual
protoplasm, which contains the last remnants of the reserve
nutrition stored up by the sporont. The protoplasm of the
sporozoites is clear and finely granulated. Each sporozoite
is typically sickle-shaped with the nucleus in the middle. Some-
times the nucleus is at one extremity, and the sporozoite then
has a form more resembling a tadpole (Fig. 38).

The spore -envelope or sporocyst consists of two layers, an
outer clear and delicate epispore, and an inner refringent and tough
endospore. Sometimes these two
layers are quite separate, or, on the
other hand, they may be intimately
united. In external characters the
spores show the greatest possible
variety of form and pattern, and
are frequently ornamented with
long tails or processes, which may
vary considerably even in closely
allied species, as in the species of
Cystobia infesting Holothurians (Fig.
38). Another remarkable feature
seen in some genera is the union of
the spores by their sporocysts to
form strings or ropes ("spores en
chapelet") (Fig. 34,/).

of

With regard to the dissemination

n

the spores, and the manner
which they infect new hosts,
is nothing to add to what
has been stated above with re-

FlO. 33.

Spores ofPyxinia rubecula, Hamin. (par.
Dermestes spp.). a, a ripe spore showing
distinct epispore and endospore. b, the
endospore set free after bursting of the
epispore. After extrusion of two polar
spheres (n), the sporozoites (s) escape from
the spore. (From Wasielewski, after Leger.)

gard to Monocystis (p. 163) and

Sporozoa generally (p. 166). In no case is a true intermediate
host known to occur. The life-cycle of Gregarines is, in the vast
majority of cases, monogenetic, and consists of sporogony only,

190

THE SPOROZOA

as described above for Monocystis. The cases in which proliferation,
by other methods than the usual spore-formation, has been alleged,
are for the most part very doubtful, and, though not incredible,
are highly improbable for reasons already put forward in dealing
with Monocystis. There are, however, a few well-attested cases of

FIG. 34.

Spores of various Gregarines. a,
simple oval spore, type of Eirmocystis,
Sphaerocystis, etc. (Gregarinidae). b,
cylindrical spore, type of Echinomera,
Dactylophorus, Pterocephalus, etc. (Dac-
tylophoriduc). c, barrel-shaped spore,
type of Gregarina and other Grega-
rinidae with sporoducts. d, navicular
spore of Beloides (Actinocephalidae).

e, biconical spore with spines of
Ancyrophora (Acanthosjwridae). f,
purse -shaped spore typical of
Stylorhynchidae. g, crescent-shaped
spore typical of Menosporidae. h,
sac -like spore of Gonospvra tere-
bellae (K611.). i, tailed spore of
Ceratospora. j, tailed spore of Uro-
spora synaptae, Cuen. (From
Wasielewski, after Leger.)

schizogony, which is correlated in Eugregarinae, as shown by
Caullery and Mesnil [10], with an intracellular stage of long dura-
tion, and takes place during this phase of the life-history. Thus
in Gonospora longissima, Caull. et Mesn., from the Annelid Dodecaceria
concharum, the nucleus of the intracellular trophozoite multiplies
by division, and the body divides into six or eight merozoites
arranged as a "corps en barillet " (see p. 222). The merozoites
then separate, escape from the host -cell, and develop into the
intercellular sporonts. Another and similar case has been

THE SPOROZOA 191

observed by Caullery and Mesnil [8&] l in a species of Selenidium
from Spio fuliginosa. In the Schizogregarinae, on the other hand,
schizogony is of constant occurrence, as their name implies, and
takes the form of multiple fission during the free extracellular
phases of the life-history.

CLASSIFICATION.

The systematic arrangement of the Gregarinida that follows is taken
from Labbe's " Sporozoa " [4], for the most part, but with some additions
or modifications necessitated by recent advances in our knowledge of the
group.

SUB -ORDER I. SCHIZOGREGARINAE, Le"ger (Amoebosporidia auct).
Gregarinida in which schizogonic reproduction takes place during the
extracellular phase of the trophozoite, in addition to the ordinary
sporogony.

The forms composing this sub-order have been regarded until recently
as a very problematic group. Their position in the Sporozoa and their
affinities with other members of the class have been considered doubtful
and altogether uncertain. Up to the end of the nineteenth century the
group was represented only by two species of Ophryocystis, except for the
fact that the supposed cancer-parasite has been referred to it by some
authorities. The misconception which has prevailed with regard to the
natural position of these forms appears to be largely due to the fact that
the species of Ophryocystis were originally described as amoeboid, and this
character was supposed to be diagnostic of the order represented by them,
hence termed Amoebosporidia.

The recent investigations of Leger [20, 21, 25], however, have not
only made known an allied form, Schizocystis, which has a fixed body-form
like other Gregarines, but have demonstrated that even Ophryocystis is not
amoeboid, as originally described, but has a definite orientation of the
body, the apparent pseudopodia being merely stiff processes of attach-
ment (Fig. 21). There can be no question that the natural position of
the group is amongst the Gregarines ; indeed it is difficult to find any
constant diagnostic character, except the mode of reproduction, separating
Ophryocystis and Schizocystis, the only two genera known at present, from
the rest of the order.

Genus 1. Schizocystis, Leger, 1900, for S. gregarinoides, Leger, from
the intestine of a dipterous larva, Ceratopogon sp. The trophozoites
are cylindrical and elongated, about 150 /u, in length, with an anterior
clearer region, and occur fixed to depressions in the intestinal wall. They
resemble a Monocystid in general appearance, but while uninucleate in
the youngest stages, the full-sized individuals may have as many as sixty
nuclei. The body then divides up to form a number of merozoites, which
become trophozoites of the second generation. The latter are uninucleate,
and when full -sized they associate and become encysted, giving rise to
gametes which conjugate and produce octozoic spores, exactly after the

1 Whose figures, however, are far from convincing.

THE SPOROZOA

pattern of Monocystis. Genus 2. Ophryocystis, A. Schneider, 1884. Several
species are known, all from the Malpighian tubules of beetles ; type-
species 0. biitschlii, A. Schn., from Blaps mortisaga (Fig. 31). The body
of the trophozoite is of irregular form, with pseudopodium-like processes
(Figg. 21, 31, and 35). The trophozoites of the first generation have
several nuclei (apparently not more than six or eight) when full-sized,
and then divide up to form as many small individuals of the second
generation, which often remain connected together for some time (Fig.

Fio. 35.

Stages in the life-history of Ophryocystis francisci, A. Schn. (par. Akis spp.). a, rosette of
six small uninucleate individuals produced by division of a schizont ; 6 and c, individuals
detached from a rosette, in 6 still showing the process of attachment ; d, rosette of four indi-
viduals ; e, sporont ; /, association of two sporonts ; g, cyst with single spore and two masses
of residual protoplasm. (From Wasielewski, after A. Schneider.)

35, a, d), but ultimately separate and become the uninucleate trophozoites
of the second generation. The latter, when adult, associate and become
encysted, and then give rise to a single octozoic spore, after elimination of
nuclei and conjugation of a surviving pair, as described above (p. 188).

SUB-ORDER II. EUGREGARINAE, Leger. Gregarinida in which schizogonic
reproduction is of very exceptional occurrence, and takes place only
during the intracellular phase, if at all. Spores octozoic with the rarest
exceptions.

TRIBE 1. ACEPHALINA, Kolliker (Monocystidea, Stein). Eugregarinae
in which the body is non-septate, and without an epimerite at any stage.
Chiefly " coelomic " parasites.

THE SPOROZOA

193

Genus 3. Monocystis, Stein, 1848. Trophozoites characterised by
considerable contractility, and consequent changeability of body -form.
Spores navicular. Several species from Oligochaetes, one from Clymenella
torquata, and one from Diap-
tomus and Cyclops, all inhabit-
ing the vesiculae seminales or
general body-cavities of their
hosts. Type M. agilis, Stein
(Figg. 2-8). The genus Sper-
matophagus, Labbe, 1899 (nom.
nov. for Spermatobium, Eisen,
1895, preoccupied), for two
species parasitic in the vesi-
culae seminales of earthworms,
is apparently a synonym of
Monocystis. Genus 4. Zygocystis,
Stein, 1848. Adult tropho-
zoites generally piriform,
always found associated in
couples or threes (Fig. 36) ;

spores biconical. Type Z.

cometa, Stein,from the vesiculae

seminales and general body-

cavity of Lumbricus agricola. Two other species are known. Genus 5.

Zygosoma, Labbe", 1899 (nom. nov. for Conorhynchus, Greeff, 1880, preoccu-

pied). Trophozoites pear-shaped, the entire body covered with finger-like

processes, the endoplasm filled with vacuoles ; always associated in coxiples

FIG. 36.

Zygocystis cmneta, Stein (par. Lumbricus cmnmunis
* tW° individuals : b' of

FIG. 37.

Pterospora maldaneorum, Rac. et Lab. (par. Liocephalus liopygus and Clymene lunibricalis).
a, two associated trophozoites ; the individual on the left is fully expanded, that on the right
is commencing to retract its processes. 6, spore showing the sporozoites coiled spirally round
the central mass of granular residual protoplasm, c, transverse section of a spore showing the
three wing-like processes and the sporozoites (four of them) in the section round the central
residual protoplasm.

when full-grown. Sporulation unknown. Unique species Z. gibbosum
(Greeff) from the gut of Echiurus pallasii. Genus 6. Pterospora, Bacovitza
and Labbe, 1896. Trophozoites pear-shaped, the smaller extremity bearing
two groups of finger-shaped retractile processes, four in each group ; always
found associated in couples. Spores with dissimilar poles, the epispore
prolonged into three lateral wing- like expansions. Unique species P.

13

194

THE SPO-ROZOA

maldaneorum, R. and L. (Fig. 37), from the coelom of Liocephalus liopygus and
Glymene lumbricalis. Genus 7. Cystobia, Mingazzini, 1891. Trophozoites
large, oval or irregular in form, with two nuclei, resulting probably from
early fusion of associated individuals (Fig. 23).
Spores with dissimilar poles, the epispore form-
ing a funnel-like projection at one pole, some-
times also a tail-like expansion at the other
(Fig. 38). Parasites of Holothurians occurring
in the blood-vessels, whence the cysts dehisce
into the coelom. Type G. holothuriae (Ant.
Schn.) from Holothuria tubulosa. Genus 8.
Lithocystis, Giard, 1876. Trophozoites large,
ovoid or vermiform, with the endoplasm filled
with crystals of calcium oxalate. Spores with
long tubular processes of the epispore at one
spores of ^Cy'stoUa irregu- Pole' Unique species L. schwideri, Giard (Fig.
laris (Minchin), (par. Holothuria 39), from the coelom of various Echinids.
Sffli^^iSKS,^ Genus 9. Ceratospora, Leger, 1892. Tropho-
losa). (After Minchin.) zoites of elongated conical form, associating by

their truncated extremity, and giving rise to

spores without encystment and without change of external form. Spores
oval, with a collar-like expansion at one extremity, and two long rigid
filaments at the other (Fig. 34, •&). Unique species G. mirabilis, Le"g., from
the body-cavity of Glycera sp. Genus 10. Urospora, A. Schneider, 1875.
Trophozoites large, spores oval, with a caudal filament at one pole (Fig.
34, j). U. saenuridis (Koll.), from the vesiculae seminales and coelom of
Tubifex rivulorum. Other species from Nemertines, Sipunculus, Synapta,
etc. Genus 11. Gonospora, A. Schneider, 1875. Trophozoites ovoid,
piriforrn, or vermiform (Fig. 20). Spores with dissimilar poles, rounded
at one extremity, bearing one or more tooth-like processes at the other
(Fig. 34, K). Four species, all from the coelomic cavities of Polychaeta.
Type G. terebellae (Koll.), from Terebella, etc. Genus 12. Syncystis, A.
Schneider, 1886. Trophozoites ovoid or piriform. Spores navicular with
four divergent bristles at each extremity. Unique species S. mirabilis, A.
Schn., from the body-cavity and fat-body of Nepa cinerea. Genus 13.
Diplocystis, Kiinstler, 1887. Trophozoites of "coelomic" habitat, associat-
ing precociously to form spherical masses. Spores spherical or oblong.
D. schneideri, Kunst., from the body-cavity of Periplaneta americana. D.
major, Cu6n., and D. minor, Cuen. (Fig. 22), from the common cricket.
Genus 14. Lankesteria, Mingazzini, 1891. Trophozoites more or less
spatulate (Fig. 13). Spores oval (compare Fig. 29, f). Type L. ascidiae
(Lank.), from the gut of Ciona intestinalis. The sporozoan parasite described
by Pollard,1 from the intestinal epithelium of Amphioxus, is identified by
Labb4 as the intracellular stage of a Gregarine belonging to this genus.
Genus 15. Callyntrochlamys, Frenzel, 1885. Trophozoites with the body
constricted into two regions not separated by any septum, and with
a fur-like covering of rods, resembling cilia, clothing the surface of the

1 Quart. Journ. Micr. &ci., N.S. xxxiv. p. 311.

THE SPOROZOA

195

body except at the anterior extremity. Spores not described. Type
0. phronimae, Frenz., from the gut of Phronima sedentaria. Genus 1 6.
Ancora, Labbe", 1899 (nom. nov. for Anchorina, Ming., 1891, preoccupied).
Trophozoite anchor-shaped, with two anterior lateral prolongations of the

FIG. 39.

Lithocystis schneideri, Giard (par. Echinocardium, etc.). a, an association of two of the
extremely lively trophozoites, which attach themselves loosely to one another in pairs, keeping
up at the same time very active movements. 6, two trophozoites (sporonts) about to become
encysted ; the bodies have contracted into compact motionless masses, and in each individual
vacuoles have appeared containing clinorhombic crystals of calcium oxalate ; the whole mass
is surrounded by a coat of amoebocytes from the coelomic fluid of the host, c, an unripe
spore, before formation of sporozoites, highly magnified, d, a ripe spore, c and d also show
the differences between the two kinds of spores ; e is a microspore, rf, a macrospore. n,
nucleus ; am.c, investment of amoebocytes ; cr, crystals ; /, funnel-like prolongation of the
epispore, through which the sporozoites pass out ; t, tail-like process of the epispore, tubular
in the unripe, filamentous in the ripe spore ; sp.z, sporozoites. (After Leger.)

body. Spores unknown. Unique species A. sagittata (Leuck.), from the
gut of Capitella capitata.

The following genera of Acephalina, known only in the trophozoite
phase, are insufficiently characterised : —

Genus 17. Pleurozyga, Mingazzini, 1891. Trophozoites more or less
claviform, associating laterally. Three species from Ascidians. Genus 18.

1 96 THE SPOROZOA

Ophioidina, Mingazzini, 1891. Trophozoites elongated, vermiform, the
body cylindrical, blunt at one end, pointed at the other. 0. bonelliae,
Frenz., from the gut of Bonellia viridis. Two other species are also
referred to this genus. Genus 19. Kollikerella, Labbe, 1899 (nom. nov.
for Kollikeria, Ming., 1893, preoccupied). Trophozoites of rhomboidal
form, the anterior extremity rounded and forming a sort of head,
separated by a constriction from the rest of the body. Unique species
K. staurocephali (Ming.), from Staurocephalus rudolphii. Genus 20. Lobian-
chella, Mingazzini, 1891. Trophozoites of elongated form with the
anterior end rounded. Unique species L. beloneides, Ming., from the
coelom of Aldope sp.

TRIBE 2. CEPHALINA, Delage ( = Potycystidea auct + Doliocystidae).
Eugregarinae which always possess an epimerite, which may be present
only in the young stages or may be a permanent organ. The body is
divided, typically, by a septum into protomerite and deutomerite, but may
be simple, non-septate. Parasites chiefly of Arthropods, usually occurring
in the gut.

(a) SUB-TRIBE GYMNOSPOREA, Ldger. The cyst contains naked
gymnospores (sporozoites) not enveloped in sporocysts to form spores.

FAMILY 1. AGGREGATIDAE, Labbe. Sporonts septate, forming associa-
tions of two or more individuals. Sporozoites grouped irregularly round
a number of residual masses (Fig. 32).

Genus 21. Aggregate/,, Frenzel, 1885. Trophozoites elongated,
cylindrical. A. portunidarum, Frenz., from the intestine of Carcinus
maenas and Portunus arcuatus, and several other species from other
Crustacean hosts.

FAMILY 2. POROSPORIDAE, Labbe. Each sporoblast gives rise to
numerous sporozoites grouped round a residual mass, but the " spores " so
formed are not enveloped in sporocysts (Fig. 41).

Genus 22. Porospora, A. Schneider, 1875. Epimerite minute,
button-like. Trophozoites large, septate, usually solitary (Fig. 1), some-
times associated (Fig. 40). Unique species P. gigantea (E. v. Ben.), from
the gut of the lobster.

(6) SUB-TRIBE ANGIOSPOREA, Leger. Spores well developed, with
double sporocysts composed of epispore and endospore.

FAMILY 3. GREGARINIDAE, Labbd (Clepsydrinidae, Le"ger). Tropho-
zoites with simple epimerites (Fig. 17, a). Cysts with or without sporo-
ducts. Spores oval, in forms without sporoducts (Fig. 34, a), but in forms
with sporoducts they are barrel-shaped (Fig. 34, c) and united in strings
by their flattened ends.

Genus 23. Gregarina, Dufour, 1828 (Clepsydrina, Hammer-
schmidt, 1838). Epimerite conical or knobbed, rarely large. Cysts
spherical or oval with sporoducts (Figg. 28 and 42). Spores barrel-shaped
(Fig. 34, c). G. blattarum, Sieb. (Fig. 42), from the common cockroach
Periplaneta orientalis ; G. ovata, Duf., from the earwig Forficula auri-
cularia ; G. polymorpha (Hamm.), from the meal-worm ; and numerous
other species, parasitic in the intestinal tracts of insects. Genus 24.
Gamocystis, A. Schneider, 1875. Trophozoite with transitory protom.,
resembling a monocystid. Cyst with sporoducts. Spores elongated,

THE SPOROZOA

197

FIG. 41.

Two spores of Porospora gigantea,
v. Ben. (par. Homarus vulgaris), show-
ing the numerous sporozoites planted
round a central mass of residual pro-
toplasm. (From Lankester.)

FIG. 40.

Porospora gigantea, v. Ben.
Association of three individ-
uals adhering to one another,
of which the hindermost has
no obvious protomerite. (From
Wasielewski, after Leger.)

FIG. 42.

Gregarina blattarum, Sieb. (par. Periplaneta
orientalis). 1, a syzygy of two sporonts ; a,
nucleus. 2, ripe cyst, partially emptied ; a,
channels leading to the sporoducts ; 6, the re-
maining spores ; c, endocyst ; d, the everted
sporoducts ; «, the gelatinous epicyst. (From
Lankester.)

cylindrical. G. tenax, A. Schn., from the gut
of the cockroach Ectobia lapponica ; G. ephemerae,
Frantz, from the intestine of Ephemera, larva.
Genus 25. Eirmocystis, Leger, 1892 (Hirmocystis,
Labbe, 1899). Epim. a conical knob. Sporonts
forming syzygies of numerous individuals (Fig.
24). Cysts without sporoducts. Spores oval in
form (Fig. 34, a). E. polymorpha, Leger, from
the intestine of Limnobia, larva, and other species
from the digestive tracts of insects. Genus 26.
Hyalospora, A. Schneider, 1875. Cysts without
sporoducts. Spores ellipsoidal, pointed at the
ends, bulging in the middle. H. roscoviana,
A. Schn., type-species, from the gut of Petrobius
maritimus, and two other species. Genus 27.
Euspora, A. Schneider, 1875. Cysts without
sporoducts. Spores prismatic. Unique species
E. fallax, A. Schn., from the gut of Rhizotrogus
aestivus. Genus 28. Sphaerocystis, Le"ger, 1892.
Body of trophozoite spheroidal, with transitory
protom. Cysts without sporoducts. Spores oval
in form (Fig. 34, a). Unique species S. simplex,
L4g., from the gut of Cyphon pallidus, larva.
Genus 29. Cnemidospora, A. Schneider, 1882.

198 THE SPOROZOA

Epim. large, lancet-shaped. Sporonts solitary, the body elongated and
cylindrical in form, with globular protom. Cysts without sporoducts.
Spores ellipsoidal with thick sporocysts. Unique species C. lutea, A. Schn.,
from digestive tract of Glomeris sp. Genus 30. Stenophora, Labbe", 1899
(nom. nov. for Stenocephalus, A. Schneider, 1875, preoccupied). Sporout oval,
obese, with small conical protomerite. Cysts without sporoducts. Spores
fusiform with a dark equatorial line. Unique species & juli (Frantz.),
from the digestive tract of millepedes, Julus sabulosus and terrestris,
Spirobolus marginatus.

FAMILY 4. DIDYMOPHYIDAE, Le"ger. Sporonts always associated in
pairs, one behind the other, in such a way that the protomerite of the
satellite disappears, and each syzygy resembles an individual with three
chambers and two nuclei (Fig. 25, a).

Genus 31. Didymophyes, Stein, 1848. Epim. in form of a cylindro-
conical spike (Fig. 25, 6). Cysts dehiscing by simple rupture. Spores oval.
D. paradoxa, St., from the intestine of Geotrupes stercorarius ; and three
other species.

FAMILY 5. DACTYLOPHORIDAE, Leger. Epimerite asymmetrical,
irregular, bearing digitiform or root-like prolongations (Fig. 1 7, h, i). The
dehiscence of the cysts is effected by simple rupture or by means of a
pseudocyst (p. 183) placed laterally. Spores elongated, cylindrical (Fig. 34, 6).

Genus 32. Rhopalonia, Leger, 1893. Epim. a subspherical knob
bearing flexible digitiform processes. Trophozoites solitary, the conical
body not septate, but with an indication of the protomerite. Unique
species R. geophili, Leg., from digestive tract of Geophilidae and of-
Stigmatogaster gracilis. Genus 33. Echinomera, Labbe, 1899 (nom. nov.
for Echinocephahis, A. Schneider, 1875). Trophozoite of oval or subconical
contour, massive ; epim. persistent, spiked, the point furnished with small
digitiform appendages which are not persistent, the whole forming with
the protomerite a cone with summit displaced and slightly excentric
(Fig. 1 7, h). Cyst dehiscing by simple rupture. Spores cylindrical with
rounded bases, usually in strings (Fig. 34, b). Unique species E. hispida
(A. Schn.), from the gut of Lithobius forficatus. Genus 34. Trichorhynchus,
A. Schneider, 1882. Cephalont with cylindrical or truncated protom.,
bearing an elongated conical rostrum. Cysts oblong with wart-like emi-
nences ; dehiscence by means of a lateral pseudocyst. Spores cylindrical
or ellipsoidal, not in strings. Unique species T. pulcher, A. Schn., from
the digestive tract of Scutigera. Genus 35. Pterocephalus, A. Schneider,
1887. Trophozoite with bilaterally symmetrical protom., divided into
two lobes bearing spines or root-like processes, the two lobes united at
one of their extremities to form a coiled horn (Fig. 17, i). Spores oval
in form, connected obliquely into strings. Unique species P. nobilis,
A. Schn., from the gut of Scolopendra spp. Genus 36. Dactylophorus,
Balbiani, 1889. Protom. expanded excentrically, and carrying the
digitiform processes of the epim. Sporonts solitary, of elongated form.
Cysts dehiscing by means of a lateral pseudocyst. Spores cylindrical.
Unique species D. robwtus, Leg., from the gut of Cryptops hortensis.

FAMILY 6. ACTINOCEPHALIDAE, Leger. Sporonts always solitary ;
epim. symmetrical, simple or with appendages. Cysts dehiscing by

THE SPOROZOA 199

simple rupture. Spores navicular, biconical, or cylindrical with conical
extremities (Fig. 34, d). Parasitic for the most part in the guts of
carnivorous Arthropods.

(1) SUB-FAMILY SCIADOPHORINAE, Labbe. Protom. umbrella-shaped,
with radiating ridges terminating posteriorly in recurved spines. Spores
biconical, the epispore with equatorial, the endospore with polar, dehiscence.

Genus 37. Sciadophora, Labbe, 1899 (nom. nov. for Lycosella, Leger,
1896, preoccupied), with the characters of the sub-family. S. phalangii
(Leg.), from the gut of Phalangium crassum and P. cornutum • two other
species, also from Phalangidae.

(2) SUB -FAMILY ANTHORHYNCHINAE, Labbe. Spores ovoid with
pointed ends, joined in strings by an equatorial suture.

Genus 38. Anthorhynchus, Labbe\ 1899 (nom. nov. for Anthocephalus,
A. Schneider, 1887). Epim. a large grooved knob. Unique species A.
sophiae (A. Schn.), from the gut of Phalangium opilio.

(3) SUB-FAMILY PILEOCEPHALINAE, Labb& Epim. simple, conical, or
lance-like. Spores usually biconical.

Genus 39. Pileocephalus, A. Schneider, 1875. Epim. shaped like a
lance-head (Fig. 17, c). P. heerii (Koll.), from the gut of Phryganid larvae
and P. chinensis, A. Schn., from the gut of Mystacid larvae ; . two other
doubtful species. Genus 40. Amphoroides, Labbe, 1899 (nom. nov.
for Amphorella, Leger, 1892, preoccupied). Epim. spiked or globular;
sporonts solitary ; protom. very short, compressed, hollowed out into a
cup. Spores biconical. Unique species, A. polydesmi (Leg.), from the gut
of Polydesmus complanatus. Genus 41. Discorhynchus, Labbe, 1899 (nom.
nov. for Discocephalus, Leger, 1892, preoccupied). Epim. large, in the
form of boss surrounded by a thick ring ; protom. globular, larger than
the deutom. Spores biconical, obese. Unique species, D. truncatus (Leg.),
from the gut of Sericostoma sp., larva.

(4) SUB- FAMILY STICTOSPORINAE, Labbe\ Spores biconical, with
slightly curved, pointed terminations ; the endospore with numerous little
papilliform elevations.

Genus 42. Stictospora, Leger, 1893. Epim. with a globular head,
depressed ventrally and covered with projecting ribs terminating posteriorly
in spikes. Spores biconical, the points slightly curved inwards. Unique
species, S. provinciates, Leg., from the gut of the larva of Melolmtha and
Rhizotrorjus.

(5) SUB-FAMILY ACTINOCEPHALINAE, Labbe. Epim. with appendages
(except in Stylocystis). Spores symmetrical, navicular, biconical, or
cylindrical with pointed ends.

Genus 43. Schneideria, Leger, 1892. Trophozoite non-septate ; epim.
a thick plate bordered by a rim composed of rib-like thickenings (Fig. 18).
Spores smooth, obese, biconical. S. mucronata, Leg., from the larva of
Bibio marci, and S. caudata (Sieb.), from the larva of Sciara nitidicollis.
Genus 44. Stylocystis, Leger, 1899. Trophozoite non-septate; epim. in the
form of a pointed bristle or sharp spine, usually curved. Sporonts solitary.
Spores biconical. Unique species S. praecox, Leger, from the gut of the
larva of Tanypus sp. (Diptera). While evidently closely allied to the
foregoing genus, the epimerite lacks the appendages characteristic of the

200 THE SPOROZOA

sub-family, and from the morphological point of view is intermediate
between the simple epimerite of Doliocystidae and the more complex
epimerites of Actinocepkalidae (Leger). Genus 45. Asterophora, Le"ger,
1892. Epim. composed of a circular ridge with radiating rib -like
thickenings, surrounding a prominent central papilla. Protom. ordinarily
larger than the deutom. Sporonts solitary, of elongated form. Spores
cylindrical with conical extremities. A. mucronata, Leg., from the gut of
the larva of Rhyacophila, and A. elegans, Leg., from the digestive tract of
the larvae of Phryganea grandis and Sericostoma sp. Genus 46. Stephano-
phora, Ldger, 1892. Epim. large, in form of a convex disc bearing a
crown of finger-shaped tentacles. Spores as in the last. Unique species
S. lucani (Stein), from the gut of Dorcus parallelipipedus. Genus 47.
Bothriopsis, A. Schneider, 1875. Epim. in form of a lenticular knob
bearing long flexible non- motile filaments. Sporonts solitary, with
protom. greatly developed and very mobile. Spores biconical, obese.
Unique species B. histrio, A. Schn., from the gut of Hydaticus sp.
Genus 48. Coleorhynchus, Labbe", 1899 (nom. nov. for Coleophora, A.
Schneider, 1885, preoccupied). Sporont with protom. in the form of a
sucker or strawberry, extending over the deutom. ; septum convex,
projecting into the protom. ; deutom. subspherical or cylindrical. Spores
navicular. Unique species G. heros (A. Schn.), from the gut of Nepa
cinerea. Genus 49. Legeria, Labbe, 1899 (nom. nov. for Dufouria, A.
Schneider, 1875). Protom. dilated, club-shaped ; septum convex, pro-
jecting into protom. Spores subnavicular, with thick sporocysts. Unique
species L. agilis (A. Schn.), gut of larva of Colymbetes sp. Genus 50.
Phialoides, Labbe, 1899 (nom. nov. for Phialis, Leger, 1892, preoccupied).
Epim. in the form of a retractile boss, surrounded by a circular ridge
'and a collar-like membrane with pleats terminated by triangular teeth.
Sporonts massive, solitary. Spores biconical, obese. Unique species P.
ornata (L4g.), from the gut of the larva of Hydrophilus piceus. Genus 51.
Geneiorhynchus, A. Schneider, 1875. Epim. in the form of a disc bristling
with fine pointed teeth, carried on a very elongated neck (Fig. 17, </).
Spores subnavicular. Unique species G. monnieri, A. Schn., from the
gut of the nymph of Libellula. Genus 52. Actinocephalus, Stein, 1848. *
Epim. sessile or on a well-marked neck, and provided with hooks or
spines. Spores biconical. A. stelliformis, A. Schn., from the gut of
Ocypus olens and other beetles ; and other species. Genus 53. Pyxinia,
Hammerschmidt, 1838. Epim. in the form of a cup or saucer with
fringed rim surrounding a central spike (Fig. 15). P. rubecula, Hamm.
(Figg. 15 and 33), from the gut of Dermestes lardarius and D. vulpinus ;
and other species. Genus 54. Beloides, Labbe", 1899 (nom. nov. for Xipho-
rhynchm, Leger, 1892). Epim. in form of disc or knob furnished with
about ten teeth, and bearing in the centre a long spike (Fig. 17, e). Spores

1 The two species mentioned by Stein (Miiller's Archiv, 1848) under the genus
Actinocephalus were A. acus, Stein, from Carabus glabratus and A. lucani from
Lucanus (Dorcus) parallelipipedus. The former of these is not mentioned in Labbe's
Sporozoa, the latter is placed, following Leger, under the genus Stephanophora, Leger.
These facts may necessitate a revision of the nomenclature of the genera of Actino-
cephalidae, since the genus Actinocephalus in Das Thierreich does not contain either
of the species placed in it by the founder of the genus.

THE SPOROZOA 201

elongate-oval or boat-shaped. B. firmus (Leg.), (Fig. 1 7, e\ and B. tennis
(Leg.), both from the intestines of larvae of Dermestes spp.

FAMILY 7. ACANTHOSPORIDAE, Leger. Sporonts always solitary.
Epira. symmetrical, simple or with appendages. Cysts dehiscing by
simple rupture. Spores garnished with bristles at the poles or equator
(Fig. 34, e). Parasites of carnivorous insects.

Genus 55. Corycella, Leger, 1892. Protom. spherical, more or less
dilated ; epim. in form of a knob bearing a crown of eight large hooks
(Fig. 16). Unique species C. armata, Le"g., from the gut of Gyrinus
natator, larva. Genus 56. Acanthospora, Leger, 1892. Sporonts solitary,
of elongate oval form. Epim. in form of a conical obtuse knob. Spores
oval, with a tuft of four bristles at each pole and an equatorial circlet
of sharp spines. A. pileata, Leg., from the gut of Omoplus sp., larva,
and two other species. Genus 57. Ancyrophora, Leger, 1892. Sporonts
solitary, the posterior end pointed. Epim. a knob bearing flexible or
rigid appendages in the form of recurved hooks. Spores biconical, with
polar tufts and six equatorial bristles (Fig. 34, e). A. gracilis, Leg., from
Oarabus auratus, G. violaceus, and Silpha thoracica; A. uncinata, Le"g., from
the larvae of Dytiscus, Colymbetes, Sericostoma, and Limnophilus rhombicus.
Genus 58. Cometoides, Labbe, 1899 (nom. nov. for Pogonites, Ldger, 1892,
preoccupied). Epim. a spherical knob, flattened centrally, bearing a
circlet of flexible slender filaments (Fig. 17,/). Spores with a tuft of
bristles at each pole and two circlets of equatorial bristles. G. crinitus
(Leg.), from Hydrobius, larva ; G. capitatus (Le"g.), from Hydrous, larva, gut.

FAMILY 8. MENOSPORIDAE, Leger. Sporonts solitary. Epim. sym-
metrical, with appendages, and connected to protom. by a long neck.
Cysts spherical, dehiscing by simple rupture. Spores in the form of
crescents more or less curved (Fig. 34, </). Parasites of larvae of Agrionidae.

Genus 59. Menospora, Le*ger, 1892. Epim. in form of a cup bordered
by hooks. Unique species, M. polyacantha, Le"g.,
from gut of Agrion puella, larva. Genus 60. Hop-
lorhynchus, Carus, 1863. Epim. in form of a disc
bordered by sharp teeth. Unique species, H. oligacan-
thus (Sieb.), (Fig. 43), from gut of Galopteryx virgo, larva.

FAMILY 9. STYLORHYNCHIDAE, A. Schneider.
Tropho. with body usually elongated, and epim.
symmetrical, with or without appendages. Cysts
with two envelopes closely joined ; dehiscence by
means of pseudocyst Spores pouch -like, brown or
blackish, joined in strings, and dehiscing by a split
corresponding to the most convex border (Fig. 34, /).

Genus 61. Lophocephalus, Labbe", 1899 (nom. nov.
for Lophorhynchus, A. Schneider, 1882, preoccupied).
Epim. sessile, hollowed into a cup bordered by a Flo 43

membranous rim with vesicular appendages. Protom. WopJor.^^1(S oliga.
depressed. Cysts irregular, subspherical with areolar mnthus (Sieb.), from the

TT. . r • • • / A 01 i_ \ larva of Calopteryx.

eminences. Unique species, L. insigms (A. Schn.), (prom Lankester.)

from gut of Helops striatus (Fig. 44). Genus 62.

Cystocephalus, A. Schneider, 1886. Epim. vesicular, with short narrow

2O2

THE SPOROZOA

neck. Unique species, C. algierianus, A. Schn., from the gut of Pimelia
sp. Genus 63. Oocephalus, A. Schneider, 1886. Epim. in the form of
a rounded knob carried by a short conical neck. Unique species 0.
hispanus, A Schn., from the gut of Morica sp. Genus 64. Sphaerorhynchus,
Labbe, 1899 (nom. nov. for Sphaerocephalus, A. Schneider, 1886). Epim.
small, spherical or oval, borne on a long, broad cylindrical neck, sharply
constricted below the epim. Unique species S.
ophioides (A. Schn.), from the gut of Akis. Genus
65. Stylorhynchus, Stein, 1848. The protom. of
the cephalont is prolonged into a cylindrical,
elongated rostrum, carrying at its termination the

Fio. 44.

Lophocephalus insi.gnis (A. Schn.), (par. Helops striatus), showing
the large epimerite and the nucleus with a band -shaped karyo-
some. (From Wasielewski, afteF Leger.)

Fio. 45.

Stylorhynchus longlcollis,
Stein (par. Blaps morti-
saga). On the left a cepha-
lont, with a long epime-
rite (a) attached to the
protomerite (b). On the
right a sporont, the epi-
merite having been cast
off. (From Lankester.)

small knob-shaped epim. (Fig. 17, d); protom. of the sporont rounded ;
the deutom. very elongated. S. longicollis, Stein, from the gut of Blaps
mortisaga (Fig. 45) ; and other species.

FAMILY 10. DOLIOCYSTIDAE. Epim. symmetrical, simple. Body
non-septate. Spores oval. Parasites of marine Annelids.

Genus 66. Doliocystis, Leger, 1893. Body showing no trace of
protom. or septum. Spores oval, with a thickening of the sporocyst at
one pole. D. pellucida (Koll.), from the gut of Nereis cultrifera and

THE SPOROZOA

203

N. beaucoudrayi ; D. aphroditae (Lank.), from the gut of Aphrodite (Fig.

19) ; and other species.

The following genera of Cephalina are of uncertain position : —
Genus 67. Nematoides, Mingazzini, 1891. Trophozoite vermiform,

without septum ; epim. in form of a fork or pair of pincers, borne on an

elongated neck. Unique species N. fusiformis, Ming., from the gut of Bal-

Fio. 46.

Selenidium, various species, a, comma -shaped species (" Selenidium en virgule ") from
Cirratulus cirratvs ; ep, minute epimerite, afterwards thrown off. b, semicolon-like species
("61. en point et virgule") from the same host, with very large epimerite. c-f, stages of S.
eehinatum, C. and M. (par Dodecaceria concharwin). c, free sporont ; d, syzygy of two sporonts ;
e, a spore, external view, showing the spiny surface ; /, a spore in section, showing the four
sporozoites. a and 6, x 500 ; c and d, x 300 ; e and/, x 850. (After Caullery and Mesnil.)

anus perforatus and Pollicipes cornucopia. Genus 68. Ulivina, Mingazzini,

1891. Body of elliptical form, protom. a quarter the length of the body.
The external membrane forms a continuous sac round the animal. U.
elliptica, Ming., from the gut of Audouinia filigera. Genus 69. Syria, Le"ger,

1892. Epim. knobbed, bordered by a thick ring (Fig. 17, b). Protom.
subspherical ; deutom. conical ; with numerous enclosures. S. inopinata,

204 THE SPOROZOA

Leg., from the gut of Audouinia sp. Genus 70. Selenidium, Giard, 1884,
emend. Caullery et Mesnil, 1899, incl. Esarhdbdina, Mingazzini, 1891,
Polyrhabdina, Ming., 1891, and Platycystis, Leger, 1892. Body attenuated,
vermiform, without septum, showing longitudinal striations due to myocyte
fibrillae at the surface. Epimerite slender, conical, or large and globular
(Fig. 46, a, 6). Spores spherical, spined, and exceptional amongst Greg-
arines in being tetrazoic (Fig. 46, e, f). Parasites of Polychaetes. Type S.
pendula, Giard, from the body-cavity of Nerine ; S. echinatum, C. et M.,
from the gut of Dodecaceria concharum ; other species from Scololepis fuli-
ginosa, Cirrhatuhis cirratus, and other marine Annelids. See especially
Caullery and Mesnil [86],

ORDER 2. Coccidiidea

The Coccidiidea are an order of the Telosporidia (p. 166),
characterised by the following distinctive features. They are cell-
parasites, attacking tissue - cells, and especially epithelial cells,
rarely other forms of tissue, and never blood-cells. The trophozoite
grows within the infected cell into an oval or spherical body, with
great resemblance to an ovum ; it is quite motionless, never at
any period amoeboid, and remains intracellular during at least the
whole trophic stage. The dissemination of the parasite is always
accomplished by means of resistent oocysts, the formation of which
is preceded by the conjugation of differentiated gametes in all cases
that have been thoroughly investigated. Within the oocyst the
zygote breaks up into sporoblasts (archispwes), which either become
converted into naked sporozoites (gymnospores), or into spores
(chlamydospwes), each containing from one to four sporozoites,
seldom more. In addition to this exogenous method of reproduc-
tion, or sporogony, by means of durable cysts, the life-cycle is often
complicated by endogenous multiplication, or schizogony, serving for
the increase of the parasites within the host. The schizogony is
not preceded by conjugation, and is not accompanied by formation
of any oocysts or sporocysts.

The Coccidia have attracted the attention of naturalists and medical
men for a long time past, by their frequent occurrence in the rabbit and
other Vertebrates, in which they may be present in such masses that their
presence cannot fail to be detected by simple inspection when the host is
dissected. Earlier observers often held, however, very erroneous views
as to the nature of these parasites. Hake, who in 1839 was the first to
describe Coccidia, regarded them as pathological products of the diseased
animal — in fact, as a form of pus -corpuscles ; and similar views were
held by many subsequent writers. On the other hand, a number of
authorities in the forties and fifties believed Coccidia to be eggs of
parasitic worms. Remak, in 1845, was the first to point out their
relations to Muller's " psorosperms," and in 1854 Lieberkiihn insisted

THE SPOROZOA 205

upon their affinities with Gregarines. A year later Kloss gave the first
thorough account of the life-cycle, in the case of the form infesting the
snail, subsequently named Klossia helicina by A. Schneider. Kloss's
work was also the first proof of the existence of these parasites in Inverte-
brates. The endogenous life-cycle was first described by Eimer in 1870,
in the form infesting the mouse, termed by him Gregarina falciformis;
but later (1875) made by Schneider the type of a new genus, Eimeria.
Henceforth these organisms became known as "egg-shaped psoro-
sperms " (eiformige Psorospermien, Psorospennies oviformes), and their
affinities with the Gregarines received general recognition. In 1879
Leuckart greatly increased our knowledge of the Coccidian parasites of
the rabbit, and introduced for them the new generic name Coccidium, in
the second edition of his well-known treatise upon human parasites.
From this time onwards these parasites were commonly known aa
" Coccidia " — a word often used in an extremely vague sense by writers
whose zoological knowledge is defective, and by whom it is sometimes
employed in a sense practically synonymous with the older word " psoro-
sperms."

In the eighties our knowledge of the forms of Coccidia and their life
cycles was steadily increased, chiefly by the labours of Aime" Schneider,
and in more recent years by Labbe. In the last decade of the nineteenth
century a vast amount has been written about Coccidia on account of the
connection suspected to exist between them and cancer, but this work has
been for the most part barren of results, contributing little to extend
our knowledge either of cancer or of Coccidia. It is in this period,
however, that the complete life-cycle has been gradually worked out by a
number of observers. An alternation of generations was first suggested
by L. and R. Pfeiffer, whose ideas met with the most vigorous criticism,
but a double life- cycle has now been demonstrated to be of almost
universal occurrence amongst Coccidia. Towards the end of the nine-
teenth century, also, sexual reproduction has been observed and accu-
rately studied in a number of forms. The new century commences with
an exhaustive monograph by Schaudinn upon the complete life-history
of the forms infesting the centipede Lithobius, a publication which marks
an epoch in the investigation not only of Coccidia but of Sporozoa
generally, and completes our knowledge of a most fascinating chapter in
natural history.

(a) Occurrence, Habitat, Effects on their Hosts, etc. — The Coccidia
are an abundant group of the Sporozoa, but appear to be confined,
in the matter of hosts, to three great phyla — the Arthropoda,
Mollusca, and Vertebrata.1 In the last named they are found

1 Exceptions are the Coccidian parasites discovered by Caullery and Mesnil in the
gut of Capitetta capitala [126] and other Polychaete worms [129a]. Since only the
schizogony was observed, the systematic position of these forms could not be deter-
mined ; they remain for the present, therefore, without any generic or specific
designation. On the other hand, these authors are of opinion that the alleged
Coccidian parasites in Perichaeta, described by Beddard (Ann. Mag. Ifat. Hist. (6),
ii. 1888, p. 433), are nothing more than segmenting eggs of Nematodes. It is

2O6

THE SPOROZOA

more commonly than any other Sporozoa, and have long been
familiar on account of their frequent occurrence amongst domestic
animals, both in birds and mammals, and even in man. They are
met with in all the five classes of Vertebrates more or less
commonly, and the very numerous species of the type -genus

Coccidium are almost confined

Oth to Vertebrate hosts.1 In

I^^^M^flr Mollusca, Coccidian parasites

are very common in Gastro-
poda and Cephalopoda, and
HyaloJdossia pekeneeri, Leger,
occurs in the kidneys of the
Lamellibranch Tellina ; a
species, of position as yet
doubtful, occurring also in
the kidneys of Donax (Leger
[41]). In Arthropods, Coccidia
occur sparingly in Insects,
more abundantly in Myria-
pods, but have not been found
as yet in either Arachnida or
Crustacea.

The Coccidia are chiefly
parasites of epithelial cells,
and since the infection of the
host appears to take place in
all cases by way of the
digestive tract, it is the
epithelium of the gut or of its
appendages, such as the liver
(Fig. 47), that is most often
the seat of the parasite. In
a considerable number of
cases, however, the parasitic
germs, after entering the system by way of the gut, go further
afield before settling down. Passing through the gut -wall, the
parasites are transported, probably, by the circulation of the blood
or lymph, to their specific habitat. In those cases in which
the vascular system forms the general body-cavity (haemocoele),
we find occasionally, though very rarely, what is so common
in the Gregarines, namely, Coccidia as "coelomic" parasites.2

possible that some of the supposed Coccidia seen iii Polychaeta are really intra-
cellular stages of Gregarines ; but a genuine Coccidian, Caryotropha mesnilii (Fig. 67)
has recently been described by Siedlecki [55a] from Polymnia nebulosa.

1 Exceptions are two species found in Lithobius forficatus, viz. Coccidium lacazei
(Labbe), and O. schubergi, Schaudinn.

2 An example is Adelea mesnili, Perez, 1899 [50], from the body- cavity of

FIG. 47.

Section of rabbit's liver infected with Coccidium
oviforme, Leuck. After Balbiani, from Wasielewski.

THE SPOROZOA

207

As a general rule, however, the parasite selects some particular
organ, most often the excretory organs.1 In Molluscs, especially,
the kidneys are the seat of these parasites more often than any
other organ (Fig. 48). In Arthropods this is less frequently the case,
but Eimeria nova, A. Schn., is found in the Malpighian tubules of

..-K

FIG. 48.

Klossia Jielicina, A. Schn., from the kidney of Helix hortensis, after Balbiani, from Wasie-
lewski. a, portion of a section of the kidney, showing normal epithelial cells containing con-
cretions (C), and enlarged epithelial cells containing the parasite (K) in various stages. 6, cyst
of the Klossia containing sporoblasts. c, cyst with ripe spores, each enclosing four sporo-
zoites and a patcli of residual protoplasm.

Glomeris. In Vertebrates again the kidney is very often attacked ;
in other cases amongst this phylum it is not infrequently the
spleen, and even in a few instances the testis, which is selected
by Coccidian parasites — never, however, the ovary ; so that in this

the moth Tineola biseliella ; it attacks chiefly the fat -body, but may overrun also
the pericardial cells, oenocytes, Malpighian tubules, muscles, and epidermis ; it is
never found, however, in the gut - epithelium, nor does it penetrate the nervous
system, gonads, or imaginal discs. Another example is Adelea akidium, Leger,
parasitic upon various beetles (Akis spp. ; Olocrates abbreviatus) ; it also attacks
the fat-body and the pericardial cells, but not any other organs.

1 With regard to the question of the transport of the parasites within the body of
the host, Laveran [35] has drawn attention to an association between Coccidium
metchnikovi, Lav., and a Myxosporidian, Myxobolus ovifonnis, Thel., in the gudgeon.
The Myxobolus in the liver, spleen, and kidney is found containing the Coccidium in
various phases of development, especially in the stage of cysts with spores, in which case
the Myxobolus usually contains no spores of its own. Free Coccidia not contained in
Myxosporidia are found only in the intestine. Laveran believes that the Coccidia
penetrate the Myxosporidia in the intestine, and that the latter then invade the
organs they affect, and transport the Coccidia with them. This view is contested by
Blanchard ([30], p. 161).

208 THE SPOROZOA

respect the predilections of Coccidia are the opposite of those of
Myxosporidia, which frequently attack the ovary but never the testis.
A given species of Coccidian parasite may confine its attentions
entirely to some particular organ, or it may attack several organs,
as for example Coccidium minutum, Thel., found in the liver, spleen,
and kidney of the tench ; but as a rule it is rare for a form
infesting the epithelium of the digestive tract to attack other
internal organs as well.

Coccidia during the trophic stage are always intracellular
parasites,1 and each trophozoite destroys completely the cell which
harbours it. As a rule the trophozoite lies in the cytoplasm and
does not attack the nucleus directly, but pushes it to one side, often
indenting or compressing it. The first effect of the extranuclear
parasite is to produce a considerable hypertrophy of the host-cell,
especially of its nucleus. The cell is stimulated to increased
metabolism, shown not only in rapid growth, but also in the
formation by it of fatty substances, which serve as nutriment
for the parasite and are consumed by it (Schaudinn [51]). The
effects of the parasite are not confined to the cell which harbours
it, but may extend to the surrounding tissues ; in Helix hortensis
attacked by Klossia helicina the neighbouring epithelial cells of the
kidney are stimulated to karyokinesis and multiplication, and a
proliferation of the cells of the connective tissue is induced, leading
to the formation of a fibrous envelope round the masses of Coccidia
as a healing process on the part of the host (Laveran [38]).
Ultimately, however, the infected cell is so weakened that it can
no longer assimilate, but dies and is finally absorbed by the
parasite, only a compact lump of chromatin and a small quantity
of protoplasm remaining. The parasite then passes into the
reproductive stage, either still enclosed by the remnants of the
cell it has destroyed, in schizogony, or freed from the cell, in
sporogony.

A certain number of Coccidia occur, on the other hand, as
intranuclear parasites. The schizogonous generations of certain
species of Coccidium occurring in Amphibia (frog, salamander, newt)
commonly attack the nucleus itself of the infected cell, and have
hence been described by Steinhaus under the generic name Karyo-
phagtts. The recently described Cydospora caryolytica, Schaud.,
parasite of the intestinal epithelium of the mole, owes its specific
name also to its intranuclear habitat, which in this case seems to
be an invariable characteristic of the parasite. The effects of this
intranuclear parasitism have recently been studied by Schaudinn
[5 la] and Dormoy [33], and are seen chiefly in an enlargement of

1 Very recently Laveran and Mesnil have described a species under the name
Coccidium mitrarium (see p. 233), which, according to these authors, is unique
amongst Coccidia in having an extracellular development like a Gregarine.

THE SPOROZOA 209

the nucleus, accompanied by absorption of its contents. The linin
framework is broken up, vacuoles are formed in it, and the
chromatin fuses into irregular lumps and strands. The nucleus
becomes enlarged to six or even ten times its normal diameter by
absorption of fluid from the cell. The chromatic substance is
forced out, by growth of the parasite, to the periphery of the
nucleus, and ultimately disappears, so that "the entire nucleus is
transformed into a gigantic vacuole, in the interior of which the
parasite floats-" (Schaudinn). The cytoplasm of the cell, on the
other hand, is absorbed and shrivels up rapidly as the nucleus
enlarges, without going through any stage of hypertrophy such as
results from extranuclear parasitism.

Each individual trophozoite in this way brings about the destruc-
tion of a cell, but of one only, in its host. Nevertheless, the parasites
are often present in such vast numbers that the epithelium of the
organ affected may be completely destroyed, and the host itself
killed or reduced to the last extremity. In centipedes experi-
mented upon by Schaudinn, the faeces became milk-white during
the acute stage of the Coccidiosis, and consisted entirely of epithelial
remains and Coccidian cysts. The intestine may be so stripped of
its epithelium that the young sporozoites are unable to find an
epithelial cell to infect, in which case they may attack a full-
grown Coccidian of another species, but never of their own kind
(Schaudinn [51]). In the mole, Cyclospora caryolytica is the cause of
a pernicious form of enteritis accompanied by violent diarrhoea,
which is generally fatal to the host (Schaudinn [5 la]). In
rabbits young animals are often killed by the attacks of Coccidia
infesting the epithelium of the bile -ducts, and similar cases are
known in the human species.1 The liver is greatly enlarged, and
its blood-vessels compressed, leading to functional derangements ;
the secretion of bile is reduced to a minimum ; the blood becomes
pale and watery, as in pernicious anaemia ; the respiration becomes
gasping, and the animal finally dies in convulsions. In all these
cases the destructive power of the parasite varies directly as its
power of multiplying by schizogony, and so overrunning the tissues
which it attacks ; and it is a very interesting and important fact,
that in no case, apparently, can the schizogony continue indefinitely,
but has its own natural, intrinsic limit, after which conjugation,
with consequent sporogony, is necessary for the recuperation of the
parasite and the continuance of its race. If, therefore, the patient
can safely pass the acute stage, the disease heals itself through the
failing reproductive powers of the parasite, on the one hand, and
the regenerative capacity of the epithelium on the other. The
injury inflicted on the host is repaired more or less completely ;

1 For a full account of the pathology of Coccidiosis, with special reference to man,
see Blanchard [30].

THE SPOROZOA

but the patient is by no means immune against the consequences
of a fresh infection from without.

In other Coccidia the schizogony may be wanting altogether, or
be more limited in its duration, and in such cases the parasites are
very harmless and inflict little or no injury upon their hosts. This
is especially true of those found in Mollusca, commonly infesting,
as has been said, the kidneys in these animals.

(6) Morphology and Evolution. — The complete life-cycle of Coccidium
schubergi has been worked out so thoroughly and in such detail by
Schaudinn, that it may serve very well as a type of the whole
order, the chief variations that are known to occur being specified
afterwards.1

Coccidium schubergi is parasitic in the intestinal epithelium of
LitJiobius forfaatus, where it is commonly found in company with
two other species, Coccidium lacazei (Labb6), and Adelea ovata, A.
Schn. The infection of the centipede is started by its accidentally
swallowing cysts with its food. The cyst-wall is then dissolved by
the digestive fluids, the four spores each split lengthways, and the
sporozoites, of which two are contained in each spore, are liberated
in the digestive tract. Each sporozoite proceeds at once to attack,
and to penetrate within, an epithelial cell of the host.

The free sporozoite is a minute, sickle-shaped body 15-20/i in length,
4-6 fj, in breadth (Fig. 49, a and b, and Fig. 50, a). The anterior
extremity is more pointed and refringent, the posterior end more rounded.
The finely-granulated protoplasm, which is not limited by any distinct
cuticle, contains a spherical nucleus placed near the middle of the body,
visible in life as a clear spot, and showing after preservation and staining
a number of chromatin granules, lodged in an alveolar linin framework,
but no special central corpuscle, nucleolus, or karyosome. The sporozoite
performs active movements of various kinds. In the first place, it
changes its form, as a whole, either by bending the body like a bow, and
then straightening it out again, or by ring-like constrictions of the body

1 In the following account of the life-histories of Coccidia, the terminology employed
for the various stages is that which has been gradually evolved by numerous authors
during recent years, and to which Schaudinn has put the finishing touches. The chief
departures here from Schaudinn's nomenclature are, that the term " zygote " is used
instead of " copula," and that the term " oocyst " is understood to mean the membrane
rather than the contents. In many recent memoirs some of these special terms are
employed in different senses, making the descriptions often very difficult to under-
stand. The commonest instance of this is the use of the term " macrogamete " to
denote what should be termed a female merozoite or macromerozoite (see p. 223).

Some authors, amongst whom Lang and Grassi are especially prominent, make use
of a quite different terminology, proposed originally by Haeckel. The non-sexual
schizogony is termed monogony, as being a case of reproduction by single individuals,
without conjugation, and the schizonts are termed mononts. The gametocytes are
termed gametogenous mononts, the formation of the gametes being regarded as a
special case of monogony. The zygotes or sporonts are termed amphionts, formed
as they are by the coming together of two individuals, and the sporogony is termed
amphigony.

THE SPOROZOA

211

which run from the anterior to the posterior end in waves of contraction
(Fig. 49, e and /), similar to the " euglenoid " movements of Gregarines
and Flagellates (see p. 181). During these contractile movements a fine
longitudinal striation of the body surface is to be observed, caused,
however, not by the presence of myocyte-fibrillae, but by the arrangement
of the superficial alveoli of the protoplasm in longitudinal rows (Schaudinn
[5 la]). In the second place, the sporozoite moves forward by a gliding
movement similar to that of Gregarines, and effected in a similar manner,
namely, by secretion of a gelatinous thread which pushes the little animal
forward as it is formed (Fig. 49, a and 6) ; movements of progression of
this kind alternate with movements of flexion, and after having traversed

T-N

sp.z

Fio. 49.

Movements of living sporozoites and merozoites of Coccidiuni schubergi, Schaud. (par.
Lithobiitsforficatus). After Schaudinn [51 J. a, 6, forward progression of asporozoite by secretion
of a gelatinous thread (.7.5), which is attached to foreign objects, and pushes the little creature
forwards. In b the portion of the thread between two foreign bodies has snapped and shrivelled
up. c, a merozoite in forward progression. The arrow on the left shows the direction in which
the merozoite is moving ; those on the right, the direction in which the gelatinous substance
secreted by it is flowing backwards to form a filament, d-g, penetration of an epithelial cell
by a sporozoite. H.C, host-cell ; N, its nucleus ; sp.z, sporozoite.

from five to seven times its own length, it comes to a stop, bends its
body three or four times, and starts again. Thus the sporozoite greatly
resembles in its movements and general appearance a minute Gregarine.
;By means of its progression the sporozoite reaches an epithelial cell,
and presses its anterior pointed end into it (Fig. 49, d). The opening is
widened by its euglenoid contractions, and is still further increased by
its movements of flexion and extension. In five or ten minutes it has
worked its way into the cell (Fig. 49, e-g). Its movements then slowly
cease, and it comes to rest near the nucleus, but sometimes a sporozoite
traverses four or five epithelial cells before settling down.

Within the epithelial cell the sporozoite becomes a motionless
oval body, which, absorbs the fatty nutriment provided for it by the
cell (see above, p. 208), without, however, forming any fat-granules

212

THE SPOROZOA

in its own substance or laying up any kind of reserve nutriment. It
grows rapidly, becoming in twenty-four hours a full-sized, spherical
trophozoite. Most remarkable are the changes which take place in
the nucleus during the growth of the trophozoite. Larger frag-
ments of the chromatin, which was at first scattered evenly in the
nuclear framework, collect gradually towards the centre of the
nucleus, where they soon appear imbedded in a diffuse, feebly-
refractile substance, apparently allied to plastin in nature (Fig. 50,
b). The pieces of chromatin fuse with the plastin matrix to form
a solid spherical body, homogeneous in appearance, except for a
few vacuoles of nuclear sap (Fig. 50, c-e). The body thus formed
resembles the nucleolus of Metazoan cells in its appearance and
relations, but differs in containing chromatin. It has therefore
received the distinctive name of karyosome. The karyosome lies

-ky.

FIG. 50.

Development of a sporozoite into a schizont, showing the formation of the karyosome, in
Coccidium schubergi, Schaud. (par. LUhobius forficatus). After Schaudinn [51]. a, sporozoite
with a granular chromatic nucleus (n.sp.z) but no karyosome. 6, larger granules of chromatiu
appear towards the centre of the nucleus, c, the larger granules become more concentrated.
d, they become united by a ground - substance into a central corpuscle or karyosome. e,
schizont, with a large nucleus (n.szt) containing the karyosome (ky),

towards the centre of the nucleus, or slightly excentrically. The
rest of the nuclear framework retains its finely meshed condition,
and lodges very minute chromatin -granules. The karyosome is
retained through all the stages of schizogony, and its presence is
absolutely distinctive of the schizogonous generations, but of them
alone.

When the trophozoite is full-grown and has exhausted the host-
cell, it proceeds to reproduce itself by schizogony (Fig. 51, 1-IV), and
is hence termed a schizont. The schizogony goes on within the host-
cell, the withered remains of which form an envelope to the schizont,
no cyst or protective membrane being formed by the parasite itself.
The schizonts are distinguished by their coarsely alveolar or vacuo-
lated protoplasm containing very few granular enclosures, if any.
The nucleus of each schizont divides to form a number of daughter
nuclei, which travel to the periphery and are scattered at more or
less regular intervals at the surface of the cell-body. The proto-
plasm adjacent to each nucleus then commences to grow out and

THE SPOROZOA 213

project above the surface of the schizont, taking the nucleus with
it. Thus are formed a number of club-shaped bodies, each very
similar to a sporozoite, but differing from it in certain points of
structural detail as well as in origin, and hence distinguished as a
merozoite (Figg. 51, IV, and 49, c). The parent schizont, which drops
out of the host-cell at this stage, is not converted entirely into mero-
zoites, but a certain amount of residual protoplasm is left, destined
ultimately to be cast off and to die and break up.

The schizogony here described takes place in a similar manner in
many Coccidia, and has been frequently observed since it was first
described by Eimer for the Coccidium falciforme of the mouse in 1870 ;
but until recently the connection between the different parts of the life-
cycle were not understood, and the schizogonous generations were con-
sidered as representing a distinct generic type, to which A. Schneider in
1876 gave the name of Eimeria. Hence this portion of the life-history
is often termed the Eimerian phase (" Cycle Eimerien ").

The division of the nucleus of the schizont in the process of schizogony
sketched above does not always follow the same method in all Coccidia,
not even in the three species inhabiting Lithobius. In Adelea ovata and
Coccidium lacazei it takes place by a multiple fragmentation of the nucleus
and karyosome, the fragments coming together again at the periphery in
patches to form daughter nuclei, each with a central karyosome. But in
C. schubergi the nucleus divides by repeated binary fission (Fig. 52, a-e).
The karyosome divides first in all cases, and then the chromatin
forms two masses round each of the daughter karyosomes, which play a
part in the division similar to that performed by the nucleolo-centrosome
in Euglena and Paramoeba. The process is one more akin to direct
nuclear division than to mitosis, and current descriptions, showing
beautiful nuclear spindles, are inaccurate and imaginative (Siedlecki,
Schaudinn). The number of merozoitea formed is very variable, and
is probably directly related to the nutrition furnished by the host -cell.
Usually about thirty or forty, apparently, the number may sink as low as
four. Simple binary fission of merozoites or schizonts never occurs,
however, since in all cases of schizogony, however much reduced, there is
always left a residuary mass of protoplasm on which the merozoites are
implanted all round, if numerous, or only on one side, if few.

The merozoites, at first connected by a stalk with the residual
protoplasm of the schizont, soon begin to exhibit active movements
and wriggle themselves free. Each merozoite resembles a sporozoite
in its movements and general appearance, and differs chiefly in being
more club-shaped and in possessing a distinct karyosome. The mero-
zoites proceed to seek out and to attack fresh epithelial cells, as did
the sporozoites before them, and in a similar way each merozoite
grows into a trophozoite which becomes a schizont, and breaks up
in its turn into a fresh generation of merozoites.

In this way schizogony may proceed merrily for many genera-
tions, and the numbers of the parasite increase by geometrical

214

THE SPOROZOA

THE SPOROZOA 215

progression within the host, until almost the entire epithelium of
the digestive tract may be destroyed. Sooner or later (in C.
schubergi after about five days) a limit is reached both of the
nutritive capacity of the host and of the reproductive power of the
parasite. Schizogony is then replaced by sporogony, a process
always initiated by the production of sexually differentiated con-
jugating individuals or gametes. Merozoites, descended from a long
succession of maiden schizonts, infect epithelial cells and become

Fio. 51.

The life-cycle of Coccidium schuliergi, Schaud. (par. Liihobius forficutus), represented in all
its principal stages, combined into a single diagram, after Schaudinn [51]. I-IV represents
the schizogony, commencing with infection of an epithelial cell by a sporozoite or merozoite.
After stage IV the development may start again at stage I, as indicated by the arrows ; or it
may go on to the formation of gametocytes (V). V-VIII represent the sexual generation. The
line of development, hitherto single (I-IV), becomes split into two lines— male (VI (J, VII (J,
VIII <J)and female (VI 9, VII 9, VIII 9), culminating in the highly differentiated gametes.
By conjugation these two lines are again united. IX, X show the formation of the zygote by
fusion of the nuclei of the gametes. XI-XV, sporogony.

I, two epithelial cells showing the penetration of a merozoite and its growth into a
schizont. H.C, host-cell; N, its nucleus; mz, merozoite. szt, schizont ; ky, its conspicuous
karyosome. II, the nucleus of the schizont is dividing up. Ill, schizont with numerous
daughter nuclei (n.n), each with a conspicuous karyosome. IV, the schizont has segmented
into numerous merozoites (mz), each with a karyosome in its nucleus, implanted on a
central mass of residual protoplasm, which in the figure is hidden by the merozoites. V, a
host -cell containing two young gametocytes. The microgametocyte ((J) has line granula-
tions ; the macrogametocyte (9) has coarse granules. VI 9 > a host-cell containing an
immature female gametocyte (9 game), characteristically bean -shaped, with plastinoid
granules (pl.gr) in the cytoplasm, and a distinct karyosome (ky) in the nucleus. VII 9. *
female gametocyte undergoing maturation, still in the host-cell. The body has become
spherical, the nucleus (n) irregular, and the karyosome has been expelled in fragments (ky).
VIII 9) mature macrogamete, freed from the host-cell, and sending a cone of reception towards
an approaching microgamete (J gam). VI <J, a liost-cell containing a full-grown micro-
gametocyte (cJ game), spherical, with no plastinoid granules, and with distinct karyosome
(ky). Compare VI 9- VII <J, the nucleus of the microgametocyte has divided up to form a
great number of daughter nuclei (n.n), leaving the karyosome (ky) at the centre of the body.
VIII (J , the nuclei of the last stage have become microgametes ( cJ gam), each with two flagella,
which are quitting the protoplasmic body of the gametocyte, and swimming to find a macro-
gamete. IX, the zygote surrounded by a tough membrane or oocyst (ode), and containing the
female chromatin, which is taking the form of a spindle (9), and the male chromatin in a
compact lump (<J). X, the chromatin from the two sources is spread over a spindle-like
figure (n.zyg), and no longer distinguishable as male or female. XI, the spindle-shaped nucleus
of the zygote, having become compact (n.zyg), is dividing. XII, four daughter nuclei are
formed, the nuclei of the sporoblasts (n.sp.bf). XIII, the four sporoblasts are segmented off
from a small quantity of residual protoplasm, or "reliijuat kystal" (rp). Each sporoblast has
secreted a membrane, the sporocyst (sp.m). XIV, within each sporocyst the nucleus has
divided, and the protoplasm is segmented into two sporozoites (xp.z), and a reliqwtt sporal
(rp.sp). The reliquat kystal of the last stage is absorbed. XV, release of the sporozoites. An
aperture is formed in the wall of the oocyst (ooc), and the sporozoites (sp.z) pass out through
it, having been liberated by bursting of the sporocysts (sp.m), which, with the reliquats sporaiuc
(rp.sp), are left behind in the oocyst.

trophozoites in the usual way, but instead of growing rapidly into
ordinary schizonts like their parents, they grow much more slowly
to become the mother cells of gametes, or gametocytes. Since, further,
the gametes are differentiated into male elements or microgametes,
and female elements or macrogametes, their mother cells must be
distinguished further into microgametocytes and macrogametoc/ytes,
which differ in all stages of their development.

The microgametocytes are characterised by their dense, minutely -
reticular (alveolar) protoplasm, which is very finely and evenly
granulated, and is poor in larger enclosures or reserve material
(Fig. 51, VI (£). When formation of microgametes commences,
the chromatin in the nucleus increases, fine granules of this sub-

216 THE SPOROZOA

stance being given off from the karyosome into the linin framework.
At the same time the outline of the nucleus becomes irregular and
indistinct, and it soon begins to send out processes into the cyto-
plasm, forming paths along which the chromatin-granules wander
out and travel towards the periphery of the body of the gametocyte.
They reach ultimately the most superficial layer of protoplasmic
alveoli, leaving the pallid karyosome, now almost deprived of chro-
matin, in solitary state at the centre of the body of the gametocyte.
At first scattered evenly, the minute chromatin-granules soon collect
together and become concentrated into patches disposed at more or
less regular distances from one another over the surface of the cell
(Fig. 51, VII $\ In each patch the chromatin-granules draw
more closely together and fuse into a dense mass of chromatin,
which at first has the form of an irregular tangle, but soon becomes

$&®k

chr.

fc'

•V

FIG. 52.

Division of the nucleus of the schizont of Coccidium schuberyi, Schaiul. (par. Lithobius
forficatug), in schizogony. After Schaudinn [51]. a, resting nucleus, with karyosome (ky) and
chromatin-granules (chr). b, the karyosome commences to divide, c, the karyosome forms
a dumb-bell-shaped figure, round the two extremities of which the chromatin is aggregated.

d, complete division of the karyosome, and separation of the chromatic portions of the nucleus.

e, complete separation of the two daughter nuclei.

a compact lump of chromatin enclosing a single clear vacuole. The
nuclei so formed become lengthened and drawn out so as to be first
comma-shaped, arid then elongated and filamentous in form (Fig.
51, VIII $ ) ; each nucleus bends upwards so as to project from
the body of the gametocyte, enveloped in a sharply-limited zone of
hyaline protoplasm, from which two flagella grow out ; active move-
ments are at once set up by the flagella ; and finally the nucleus
breaks loose with its protoplasmic envelope and flagella, and is set
free from the gametocyte as the minute and extremely active micro-
gamete, the male element in conjugation. The microgametes swim
off and swarm away in quest of the macrogametes, leaving the
body of the microgametocyte, which is not sensibly diminished in
bulk by subtraction of the microgametes, and which, with the
karyosome still in its heart, is abandoned as residual protoplasm,
and soon breaks up and dies. It is evident that the formation of
microgametes is nothing more than a peculiar type of schizogonous
generation, which differs in certain points, both of method1 and

1 But the method is subject to variations in both cases, in Coccidia generally, and
the difference between the formation of the microgametes and ordinary schizogony

THE SPOROZOA

217

result, from the ordinary pattern, and marks the full stop to re-
production by schizogony.

Each microgamete has a flexible, serpentine body, 6-7 //. in length by
barely 1 p, breadth in Coccidium, schubergi (Fig. 53, a, b, d, e). It may be
extended at full length, or bent up into the form of a U by its own activity.
The substance of the body consists principally of chromatin, which, however,
contains the above-mentioned vacuole in its interior, and is itself enclosed in
a delicate covering of protoplasm,
from which spring the two
flagella, one at each end of the
body. At the extremity, which
is anterior in movement, the
protoplasmic envelope is more
condensed to form a shining
point or rostrum (r). From the
base of the rostrum springs the
anterior flagellum (a.fl\ the chief
agent in forward movement ; it is
very fine and slender, about twice
the length of the body, planted
on the side which is convex when
the body is curved, and directed
backwards. The posterior flagel-
lum (p.fl) is a simple continuation
of the hinder end of the body ;
it is shorter than the anterior
one, and acts more as a rudder
(" Schleppgeissel "). The micro-
gamete as a whole thus bears a
striking resemblance to the an-
therozoid of a moss-plant.

In Coccidium lacazeiand Adelea
ovata the formation of the micro-

U

FIG. 53.

Microgametes of Coccidium schubergi, Schaud.
(a, b, d, e), and C. lacazei (Labbe), (c, /). a, 6, and c
are drawn from the living objects ; d, e, and /,
from specimens preserved and stained. After
gametes differs in One important Schaudinn [51], x about 2000. a.fl, anterior flagel-

point from the ' process described ^^
above. When the nucleus of 'ong enough.)
the microgametocyte breaks up,

the karyosome divides up first, and its fragments travel to the periphery
and act as centres round which the chromatin is concentrated to form
the nuclei of the inicrogametes. Hence each microgamete possesses a
karyosome. The microgametes of C. lacazei (Fig. 53, c and /) are
smaller (3-4 //, in length) than those of 0. schubergi, though otherwise
similar, but those of A. ovata have no flagella, and move by undulations
of the whole body.

The macrogametocytes are distinguished both from ordinary
schizonts and from microgametocytes chiefly by two points (Fig. 51,

may be much less marked than is the case in Coccidium schubergi; compare especially
the case of Caryotropha mesnilii (p. 223 and p. 225).

2i8 THE SPOROZOA

VI ? ). In the first place, they are more or less bean-shaped, and
only become spherical during the maturation stages. In the second
place, they are early marked out by the fact that from the youngest
stages of the trophozoite onwards, they store up in their cytoplasm
large quantities of reserve material in the form of the so-called plas-
tinoid granules, bodies varying in diameter from \ p. to 1 /x, and very
refringent, rendering the macrogametocytes whitish and opaque.
The protoplasm is coarsely alveolar, and contains also another kind
of granule less abundantly. The quantity of food-substance which
the macrogametocytes store up retards their development consider-
ably, so that they lag behind the male cells in this respect.

The plastinoid granules are very characteristic of Coccidia, and consist
of a substance termed Coccidin by Labbe, which resembles, but is distinct
from, the granules of paraglycogen, pyxinin, etc., found in Gregarin.es.
The plastinoid granules are stained yellow by iodine (not wine-coloured,
like the paraglycogen granules), and retain this colour after treatment with
sulphuric acid ; they are not soluble in weak acids or alkalis, nor in ether,
chloroform, or alcohol. They are not stained by haematoxylin solutions,
nor by Heidenhain's Iron- Alum method, nor yet by picrocarmine or borax-
carmine ; they are evenly stained, like the protoplasm, by Eosin, Aurantia,
and Thionin ; and Rhumbler's Eosin-Methyl Green, mixture tinges them
red. The other kind of granule mentioned above is distinguished by taking
haematoxylin stains, especially by Heidenhain's method. (See Schaudinn
[51], p. 250 ; Wasielewski [7], p. 51 ; and references.)

Each macrogametocyte becomes a single macrogamete, and to
this end it goes through a process of maturation which has some
points of resemblance to the development of the microgametes, but
differs as widely as possible in detail (Fig. 5 1, VII ? ). The schizogony
is completely suppressed, and maturation is effected simply by the
expulsion of the karyosome, which travels during the space of about
one hour from the centre to the periphery of the nucleus. It then
passes out into the cytoplasm, and there breaks up at once with ex-
plosive rapidity into numerous small fragments which are expelled
from the cell-body. During these events the macrogamete changes its
bean-shaped form by slow contraction into a spherical one, the entire
process lasting about two hours. Schaudinn suggests that it is the
plastinoid granules which by their pressure during the changes of
body-form squeeze out the fragments of the karyosome from the
cytoplasm, as a cherry-stone can be squeezed out of a cherry. The
contractions of the body have also the further effect of setting free
the macrogamete from the shrivelled host-cell, so that it now lies
free in the lumen of the gut of the host. The mature macrogamete
is a spherical cell with a large spherical pronudeus, as it may now be
termed, containing chromatin- granules but no karyosome. It is
now ripe for fertilisation, and is attractive to the microgametes,
many of which swarm round the macrogamete, but only one effects

THE SPOROZOA 219

the actual fertilisation (Fig. 51, VIII ? ). At one spot the female
pronucleus approaches the surface of the macrogamete, and here a
" cone of reception " is formed as a little prominence of clear hyaline
protoplasm, from which a thin streak of similar substance extends
as far as the nucleus. A microgamete touches the cone and adheres
to it. The cone of reception is at once drawn in, and partly in this
way, partly by its own movements, the microgamete penetrates the
macrogamete, and its pronucleus reaches the female pronucleus. No
sooner is the entry of the microgamete completed than a clear
membrane, gradually increasing in distinctness, appears over the
whole surface of the zygote, excluding the less fortunate micro-
gametes, which die oft' and break up (Fig. 51, IX). The clear
membrane very soon becomes an exceedingly tough protective
envelope, the oocyst (ode), within which, after fusion of the two
pronuclei of the zygote, the sporogony runs its course. When the
oocyst is completely formed, the parasite is in a condition to abandon
the shelter of the host and to brave the outer world. The further
development can take place inside or outside the host, indifferently.

It is apparent that the process of conjugation in the Coccidia bears
the greatest resemblance to the fertilisation by the sexual process in
animals and plants. Schaudinn has observed some curious points of
considerable interest in this process. Before the macrogamete has expelled
the fragments of its karyosome from the cytoplasm, it is not attractive to the
microgametes, but no sooner has it done so than they are drawn to it as
by a magnet. The attraction, which is evidently exerted by the substance
of the karyosome itself, acts very suddenly, and reaches from 48 p. to
130 p.. If exerted near to developing microgametes, it stimulates them
to great activity ; even still imperfect microgametes then develop
flagella, and in their struggles to free themselves from the micro-
gametocyte they carry away lumps of protoplasm with them. The
substance of the karyosome seems to be absorbed by the microgametes
that swarm to it, and the remarkable fact was observed that the attractive
power of the macrogamete was limited as regards the number of micro-
gametes drawn to it, the usual number being about twelve or fourteen.
When this number was made up, fresh microgametes approaching the
macrogamete were no longer attracted. After the substance of the
karyosome has dissolved up, a fresh attraction seems to be exerted by the
female pronucleus, which travels to the surface.

The fusion of the two pronuclei in the zygote takes place in a very
remarkable manner. The female pronucleus passes back to the centre of
the zygote and becomes drawn out in the form of an elongated spindle,
on which the chromatin granules are arranged in parallel rows running
in a meridional direction (Fig. 51, IX). The male pronucleus, at first
huddled up at one pole of this nuclear spindle, also breaks up into granules
of chromatin, which mingle with those of the female pronucleus, and cause
the spindle to increase in size until it finally stretches through the entire
oocyst (Fig. 51, X). One pole of the spindle marks the point of entry of

THE SPOROZOA

the microgamete, where its disappointed companions are still to be seen
outside the oocyst. The peculiar spindle-like arrangement of the nucleus
in the zygote has nothing to do with nuclear division, but is simply a
means of mixing intimately the chromatin derived from two different
sources, and when this is effected the spindle contracts and rounds itself
off, the final result being a spherical nucleus, the fusion-product of the two
pronuclei. It is usually in the stage with the fertilisation-spindle that
the oocyst passes out of the body of the host.

The nucleus of the zygote proceeds to divide by the direct method
(Fig. 51, XI, XII), first into two, then into four nuclei, round each
of which the protoplasm segments into four masses, the sporoblasts
(archispores, Labb6). A certain amount of granular protoplasm is
left over as a cystal residuum, which occupies the centre of the cyst

between the four sporoblasts,
and is slowly absorbed during
the further development. Each
sporoblast acquires an oval
form, the nucleus being at the
centre (Figg. 51, XIII, and 54,
a). On either side of the
nucleus there is a clear spheri-
cal vacuole, one of eight similar
vacuoles formed in the zygote
containing a viscid substance
derived, apparently, from the
plastinoid granules before the
sporoblasts were segmented off.
The sporocyst is now secreted
round the sporoblast in two
coats ; the gelatinous epispore
appears first, then internal to

Development of the spore of Cocc.idium schuliergi,
Schaud. After Schaudinn [51], x 1500. a, sporoblast
with spore-membranes, single nucleus, and two
vacuoles. 6, the nucleus is dividing, c, two nuclei

placed at the two poles of the sporoblast, exter- become the SWTe. As SOOn as
nally to the vacuoles. d, the vacuoles fusing , . , ,

together, e, two sporozoites, arranged tete-b&he, the Sporocyst IS Complete, the

and a residual mass of protoplasm containing the _,,_i_., ~{ 4.1... j- -j „

vacuole. /, the sporocysts splitting and the two nucleus Ot the Spore divides,

sporozoites escaping, n, nucleus; vac, vacuole; ao-airi bv t.ViP rlirppf mprVmrl

en.sp, endospore ; ep.sp, epispore ; sp.z, sporozoite j ,$>. °J .

r.p.sp, residual protoplasm of the spore. (r Ig. 54, 0 and C). The tWO

daughter nuclei place them-
selves at the two opposite poles of the spore, while the two clear
spheres come together at the centre and fuse into an oval body (Fig.
54, d). The protoplasm of the spore now segments into two sporo-
zoites, each with a nucleus, and a central mass of residuary protoplasm
containing the above-mentioned oval body, and also a number of
plastinoid granules ejected from the sporozoites, which have coarsely
alveolar protoplasm free from large granules (Figg. 51, XIV, and 54,e).

- sp.z.

rpsp:

Fio. 54.

it the tough refringent endo-
spore. The sporoblast has now

THE SPOROZOA 221

With the formation of the sporozoites the life-cycle has been brought
back to its starting-point, and requires only the infection of a new
host.

The sporogony takes two or three days in Ooccidium schubergi ; in C.
falciforme of the mouse it takes as long as four days. The clear spheres
mentioned above in the sporoblasts and spores can be isolated by crushing
the spore, and are viscid, plastic bodies which dissolve in dilute or strong
acids, and which, when treated with weak acetic or hydrochloric acid,
swell up before dissolving — a property which Schaudiun believes to be
largely instrumental in the bursting of the spore-envelope in the gut of a
new host. The first effect of the digestive juices is to produce an aperture
in the wall of the oocyst (Fig. 51, XV). Then the sporocysts burst
with a distinct jerk, always along an even meridional line, which, if
preformed, cannot be detected beforehand. The sporozoites lie tete-beche
within the spore, and creep out in different directions (Fig. 54, /).
The oocysts, sporocysts, and residuary bodies are left behind and cast
out with the faeces.

The infection of the Lithobius is always a casual one, by way of the
digestive tract. Sometimes a centipede becomes infected by eating another
of its kind ; infection then is conveyed not only by the oocysts, but by
all other stages except the immature, not fully -grown schizonts or
gametocytes, which pass out with the faeces after digestion of their host-
cells. Frequently the faeces of infected centipedes are eaten by wood-lice
(Oniscus and Porcellio). The contained oocysts then pass through the gut
of the wood-louse quite unaltered ; but if a wood-louse containing an
oocyst be eaten by a centipede, the latter will become infected. In this
case the wood-louse is not an intermediate host, but a simple carrier.

It follows from the mode of infection that centipedes living in a con-
fined and restricted area have a much greater chance of taking the
infection from one another, and Schaudinn found that a very large
proportion of the specimens of Lithobius obtained by him from outhouses
in the grounds of the Zoological Institute at Berlin were infected with
the parasites, but that Lithobii collected in the woods and forests were
generally free from them.

In moles infected by Cyclospora, Schaudinn [5 1 a] found that the
infection was not transmitted by cannibalism, although these pugnacious
animals frequently eat each other. He believes that in nature the mole
becomes infected by eating wood-lice and other dung-feeding Arthropods,
which have fed on the faeces of other infected moles.

The variations in the morphology and development of other
Coccidia, as compared with the type here selected, are best con-
sidered under two heads : first, structural and morphological
variations in the individual stages of the life -history; secondly,
variations in the composition of the life -cycle considered as a
whole.

(1) Morphology. — Some of the differences between Coccidium
schubergi and its two colleagues, C. lacazei and Adelea ovata, have

222

THE SPOROZOA

already been noticed incidentally, but a few other points require
special mention in other forms.

The schizogony is usually very similar in its characters to that
described above, and always lacks cyst-membranes of any kind, whether
round the schizont as a whole or in the form of spore-envelopes. The

FIG. 55.

Schizogony of Addea ovata, A. Schn. (par Lithobius forflcatus), after Siedlecki [55]. a-c, ?
generation ; d-f, <J generation, o, full-grown ? schizont (?>iacroscAt«07iO, with a large nucleus
(n) containing a conspicuous karyosome (ky). b, commencement of schizogony ; the nucleus
has divided up to form a number of daughter nuclei (d.n), each consisting of a number of
rods of chromatin arranged in a star-shaped manner in a clear space. The karyosome of stage
a has broken up into a great number of daughter karyosomes, each of which forms at first
the centre of one of the star -shaped daughter nuclei; but in a short time the daughter
karyosomes become inconspicuous, and seem to be absorbed, or to be got rid of in some way.
c, completion of schizogony ; the $ schizont has broken up into a number of nutcramerozoites
( $ mz), implanted on a small quantity of residual protoplasm (r.p). Bach ? inerozoite has
a chromatic nucleus (n) without a karyosome. d, full-grown (J schizont (microschizont),
with nucleus (n), karyosome (ky), and a number of characteristic pigment-granules (p.gr).
e, commencement of schizogony. The nucleus is dividing up into a number of daughter nuclei
(d.n), each with a conspicuous karyosome (ky). f, completion of schizogony. The numerous
micromerozoites ( <J mz) have each a nucleus with a conspicuous karyosome (ky) at one pole,
and the protoplasm contains pigment-granules (p.gr) near the nucleus, on the side furthest
from the karyosome.

term " Eimerian cyst," so frequently employed, is therefore a misnomer.
There is always a large amount of residuary protoplasm, and when the
formation of the merozoites is completed, they very frequently take on a
characteristic arrangement, like that of the divisions of an orange or the
staves of a barrel ; hence this stage is termed by French writers the
"corps en barillet" ; it is homologous with the "stade en rosace" of the

THE SPOROZOA 223

Haeinosporidia. When the merozoites are very numerous they may be
disposed in a double series. The remarkable form parasitic on Polymnia,
recently described by Siedlecki [55a] under the name Caryotropha
mesnilii, presents an interesting divergence from the usual type of
schizogony. The schizont divides first into ten or fifteen large rounded
cells, termed by Siedlecki schizontocytes (Fig. 67). Each schizontocyte
then gives origin to twenty or thirty merozoites, so that the host-cell
finally contains not one but many "barillets" (Fig. 67, d). This method
of schizogony recalls the formation of spores in Porospora (see above,
p. 188), and is also interesting for its relation to the formation of the
gametes (p. 225).

In Coccidium schubergi and most other Coccidia the schizonts
show no trace whatever of sexual differentiation until the final
term of the schizogony, when they become gametocytes of two
kinds, distinct from one another and from the ordinary schizonts. A
most important variation of this type is seen in Adelea ovata (Fig. 55)
and some other species, where the trophozoites formed from the
sporozoites exhibit sexual characters from the outset, and can be dis-
tinguished as male or female, but multiply asexually through many
schizogonous generations before finally giving rise to gametes. An
extreme case of sexual differentiation during schizogony is seen,
according to Schaudinn [5 la], in Cyclospora caryolytica from the
mole, where no differentiation can be observed in the sporozoites
themselves, but is discernible in the trophozoites produced from
them after one hour's growth. The female schizonts of Cyclospora,
have coarsely alveolar cytoplasm of very fluid consistence, and
without any reserve substances. The male schizonts are charac-
terised by the possession of strongly refractile, pigment-like granules.
The merozoites produced from the two classes of schizonts also
differ markedly both in character and arrangement. The female
gametocytes have a coarsely alveolar cytoplasm packed with
large granules of reserve material resembling yolk, while the
male gametocytes are distinguished by cytoplasm which is ex-
tremely finely granulated and stains very readily. In this
species, therefore, four distinct classes of trophozoites can be
distinguished.

In some Coccidia — for example, Adelea ovata, A. mesnili, Eimeria
nova, and Klossia helicina — the number of microgametes produced
from a microgametocyte is not indefinite, but constantly four only.
This reduction in the number of microgametes is usually correlated
with a precocious association of the gametocytes, a condition re-
sembling that which is commonly seen in Gregarines. Thus in A.
ovata the macrogametocytes when full-grown fall out of their host-
cells and pair with microgametocytes, which may be not full-sized.
The two cells adhere together, and the female cell undergoes
maturative changes, becoming a macrogamete, while the micro-

224

THE SPOROZOA

gametocyte produces four microgametes (Fig. 56). One of the latter
fertilises the ripe macrogamete, while the other three perish.

Fio. 56.

Conjugation of ' Addea ovata, A. Schu. (par. Lithobius forfleatus), after Siedlecki [55], slightly
modified, a, a microscliizont, not full-grown (compare Fig. 55, d), becomes a niicrogametocyte
( <J ga'inc) and attaches itself to a macroschizont or macrogametocyte ( 9 game), b, the nucleus
of the microgametocyte divides — c, into four daughter nuclei, which become — d, four microgamtes
( (J gam). The karyosome of the microgametocyte disappeared when division of the nucleus
commenced, e, one of the microgametes penetrates the macrogamete, which forms a fertilisa-
tion-spindle, composed of c$ and ? chro matin (chr), still distinct from each other, and occupy-
ing opposite poles of the spindle. The other three microgametes ( <$ gam), and the residual
protoplasm of the microgametocyte (r.p), containing the pigment granules, perish and dis-
integrate on the outside of the macrogamete. The karyosome of the macrogamete has broken
up, and disappeared as such. /, the complete union of the chromatin from the two sources
produces the single nucleus of the zygote (n.zyg).

Note. — In this conjugation an apparent difference in the stages is caused by the position of the
nucleus of the $ gamete, which places itself at one pole of the body, either at the pole nearest
to the microgametocyte (a, c, e) or at the pole furthest from it (b, d,f). In the first case the
fertilising microgarnete penetrates the microgamete at once, and the three residuary micro-
gametes are formed near the remains of the microgametocyte. In the second case all four
microgametes travel round to the pole furthest from the microgametocyte, where penetration
of the fertilising element takes place (/).

In A. mesnili and Eimeria nova the development is similar, but
the gametocytes may or may not associate before the maturity of

THE SPOROZOA 225

the macrogamete. In Klossia helicina precocious association of the
gametocytes occurs, but in this case the female parasite is not
set free from the host- cell. Several microgametocytes penetrate
into a kidney-cell containing a macrogametocyte, and there form
each four microgametes, one of which fertilises the macrogamete
when mature. In all these cases the economy effected in the
number of microgametes produced is probably related to the early
pairing of the gametocytes, and the consequent certainty that the
union of the gametes will be effected.

In the formation and maturation of the gametes, the most essential
feature in the instance selected is the elimination in both sexes of the
karyosome, which, like the macrouucleus of Infusoria, would appear to
represent effete nuclear substance which is cast out and formed anew at
conjugation. The karyosome is not, however, always eliminated before
the actual union of the gametes. To go no further than the Lithobius,
in Coccidium lacazei and Adelea ovata the karyosomes are retained in both
the gametes, and the same is the case in Coccidium proprium, A. Schn., of
Triton. In all these instances, however, the karyosomes are left behind
in the residual protoplasm of the oocyst, and do not pass on into spores
or sporozoites, so that the result is the same. In Coccidium lacazei,
correlated with this difference, Schaudinn observed microgametes swarm-
ing round immature, half-grown macrogametes, which they never do in
C. schubergi.

In Cyclospora caryolytica the karyosome of the male gametocyte
becomes divided each time that the nucleus divides, and the nucleus
of each microgamete contains, at first, a distinct karyosome ; but as the
nucleus assumes its definitive, elongated form, the karyosome is suddenly
ejected from it, and is left behind by the microgamete when it swims off.
In tbe macrogametocyte of this species a very interesting process of
maturation takes place. The karyosome first becomes fragmented to
form a clump of fine granules, constituting a chromatic nucleus, which
divides by a primitive form of karyokinesis into two. One of the two
daughter nuclei divides again in a similar manner. Three nuclei are
thus formed, two of which become slowly absorbed in the cytoplasm, and
represent as it were polar bodies cast off in order to bring about a
process of nuclear reduction. The third remaining nucleus becomes the
pronucleus of the macrogamete (see also below, p. 273).

In Adelea ovata, according to Siedlecki, the two consecutive nuclear
divisions to form the four microgametes are different from one another :
the first is regular and resembles karyokinesis, the second simply divides
tbe chromatin into two halves. The author believes that tbe first
division reduces tbe quantity of chromatin, the second the number of
chromosomes. In this form also a quantity of chromatin is eliminated
from the macrogametocyte at maturation, prior to fertilisation. The
maturation of Adelea ovata would thus seem to approach more nearly the
Metazoan type than does that of Coccidium sc/m&e/r/z.

In Cai~yotropha the microgametocyte does not divide up at once into
microgametes, but first into a number of spherical cells, which may be

15

226

THE SPOROZOA

termed microgametocytes of the second order, and each of which gives
rise to numerous microgametes. Hence in this form the correspondence
between the ordinary schizogony and the formation of the microgametes
is very exact (see above, p. 223).

The microgametes vary greatly in their characters. Only 3-4 p. long

FIG. 57.

Conjugation of Coccidium proprium, A. Schn. (par. Triton), after Siedlecki [53]. a, penetra-
tion of a microgamete (<$) through the micropyle (mp) of the tough oocyst (ode), by which the
female gamete is surrounded. The ? gamete only partially fills the oocyst, which it only
touches at the micropyle. Its nucleus (n) has lost its membrane, and is pear-shaped, with ill-
detined limits ; it touches the micropyle by one of its extremities, and at the opposite extremity
the chromatin (?) is aggregated in the form of a number of little rods round a central karyosome.
b, the microgamete after penetration breaks up into a mass of chromatin ( & ). The macrogamete
has withdrawn from the micropyle, leaving a plug of protoplasm (p) attached to it, which closes
the aperture. Two vacuoles (vac) have appeared in the macrogamete, containing each a little
chromatic sphere, perhaps derived from the karyosome. c, a fertilisation-spindle is formed, in
which the & and 9 chromatin granules are commingled. The two vacuoles have fused into a
single one, which persists throughout the sporulation, and is left in the residuary protoplasm
of the cyst, d, e, f, the nucleus of the zygote (n.zyg) becomes compact (d), then divides into
two nuclei (e, f), and finally into four.

in Coccidium lacazei, they reach ten times that length m Klossia, but in
each case are scarcely 1 p in breadth. The ftagella weie first discovered
by Leger in the microgametes of Barroussia caudata, Leger, from Litlwbius
martini, and in other forms. They have now been demonstrated in a
number of species ; and though usually two in number, they may vary
in position ; in the above species of Barroussia and in Coccidium oviforme
of the rabbit, both flagella are attached to the anterior end of the gamete.

THE SPOROZOA 227

Finally, in Adelea ovata, as already mentioned, and in Benedenia eberthi
(Fig. 58, c), the flagella are totally absent, and the microgamete moves
by undulating movements of the whole body.

Two interesting variations are seen in the condition of the macro-
gamete at fertilisation, which add to the striking resemblance between
this process in Coccidia and the fertilisation of the ovum in Metazoa.
In Coccidium schubergi and many others the rnacrogamete is naked until
the penetration of a microgamete into its substance has been effected,
whereupon the oocyst at once commences to be secreted, barring out other
microgametes. But in C.proprium, parasitic in newts (Fig. 57), the oocyst
is secreted round the macrogamete before fertilisation ; within the tough
membrane the protoplasm contracts and is in contact with it only at one
point, where a micropyle is formed, a minute pore through which the
microgamete enters (Fig. 57, a). When this event has taken place the
micropyle is closed up and the protoplasm withdraws from it (Fig. 57,
b and c). A fertilisation -spindle occurs in this species, similar to that
described above, but apparently less regular in arrangement. Since in
Coccidium oviforme of the rabbit the protoplasm of the macrogamete is
also contracted and does not fill the oocyst (see Fig. 62), it is not improb-
able that the envelope in question is formed before fertilisation as in
C. proprium.

In Cyclospora caryolytica the fertilisation is remarkable for the occur-
rence of polyspermy (Schaudinn [51«]). A great number of microgametes
enter the macrogamete, but only one fuses with the female pronucleus,
the others being absorbed in the cytoplasm. In other respects the
fertilisation is of the usual type, with formation of a fertilisation-spindle
and secretion of a tough oocyst round the zygote.

In the sporogony the greatest variation occurs, and as the modern
classifications of the Coccidia are founded entirely upon the character of
the spores and their formation in the different types, it is sufficient to
refer to the systematic review below for information on these points.
It may be noted, however, that the spores of Coccidia are usually of
simple form, the sporocysts not prolonged into the tails, spines, or other
processes so common in Gregarines and in Myxosporidia, the only excep-
tions to this rule being Minchinia chitonis (Fig. 66, «), Echinospora labbei
(Fig. 66, c), and Barroussia caudata ; and further, that with very few excep-
tions the number of sporozoites present in the Coccidian spore does not
exceed four, and seems never to be eight, the usual number in Gregarines.

(2) Variations in the Life-Cycle. — Although there are but few
Coccidia, relatively, in which the life-cycle has been studied in full
detail, yet some important differences have already been made
known between the different species so far investigated. It has
already been stated above that Adelea omta differs from its two
colleagues in Lithobius in the important fact that the sporozoites
which start the life-cycle in a new host give rise from the first to
sexually differentiated schizonts, which proceed to multiply by
schizogony for a number of generations before finally giving rise to
the gametes.

228

THE SPOROZOA

In Benedenia eberthi from Sepia, the sporozoites give rise to
indifferent trophozoites, which, however, when full-grown, become
gametocytes, which give rise at once to gametes, so that in this form
t/ie schizogonous cycle does not exist.

The life-cycle of Benedenia is therefore of a simple type, and

Fio. 58.

Formation of gametes and conjugation, in Benedenia eberthi, Labbe (par. Sepia), xGOO, after
Siedlecki [52]. a, adult uuditferentiated trophozoite, capable of giving rise to microgametes, or
of becoming a macrogamete. n, nucleus; ky, .karyosome. b and c, formation of microgametes.
6, the nucleus of the gametocyte has divided into numerous daughter nuclei (d.n), which travel
to the periphery and project from the protoplasmic body, c, each daughter nucleus becomes an
elongated vermiform microgamete (<J gum), composed principally of chromatin, with a small
quantity of protoplasm, d, e, f, conjugation, d, in the macrogamete the nucleus places itself
in contact with the surface of the body, and by condensation of the chromatic network a mass
of chromatin ( ? chr) is formed at the pole of the nucleus furthest from the surface of the body.
ky, karyosome ; tj gam, microgametes swarming round the macrogamete in the vicinity of
the nucleus, e, a microgamete has penetrated the macrogamete, and is broken up to form a
mass of chroniatin-granules (f chr). A membrane, the oocyst (ode), is now formed round the
zygote, excluding the other microgametes. /, a fertilisation-spindle is formed, in which the
chroniatin-granules derived from the two gametes (& and 9 chr) is commingled.

only differs from that commonly seen in Gregarines in certain
details of the conjugation. Its entire history may be expressed as
follows : —

Sporozoite-^- r? Gametocyte xnf Gametes
8Porozoite^9Gametocyte->?Gamete

(Oocyst)xm

The life-cycle of Adelea ovafa is similar, but the complication of
schizogony is introduced : —

Sporozoite-^- (J Gametocyte (Microschizont) x cJMerozoites (Micromerozoites)-^- . . .
Sporozoite-^- 9 Gametocyte (Macroschizont)x 9 Merozoites (Macromerozoites)-^- . . .

8«yrt)x»

Sporozoites.

Finally, in Coccidium schubergi and other forms the fullest com-
plication is developed : —

Sporozoite-^-Schizontx Merozoites-^- .
Sporozoite-^-Schizontx Merozoites-^- .

. SchizontsxMerozoites— >•
. Schizonts x Merozoites->-

THE SPOROZOA 229

It is thus seen that the life- cycles of the Coccidia can be
arranged in what is evidently a natural series ; but it is open to
debate which end of the series should be considered as the more
primitive, and should be taken as the starting-point of the evolution.
The tendency of modern authorities has been rather to consider the
condition in Coccidium as primitive, and to regard Benedenia as a
form in which the alternation of generations is secondarily sup-
pressed. It does not, however, seem probable that a method of
reproduction so useful to the parasite as the schizogony would have
been abandoned when once acquired, and the existence of the vast
legion of Gregarines, in which schizogony is of the rarest occurrence,
makes it probable that in Coccidia also the primitive ancestral
type was without schizogony, and that the alternation of genera-
tions has been acquired by the majority of the group as an
adaptation to parasitic life. But even assuming the correctness of
this view, it does not necessarily follow that the case of Benedenia
itself is primitive. More intimate acquaintance with the life-cycles
of different Coccidia is necessary before a definite opinion can be
framed with regard to this point.

(c) Classification. — The order Coccidiidea is divided into families
characterised by the number of sporocysts (if any) formed within
the oocyst. Generic characters are sought chiefly in the number of
sporozoites formed in each spore, and to a less extent in the form
and characters of the sporocyst. Four families are thus recognised,
but the differences which separate the first of them, the Asporo-
cystidae, from the -other three are such as should give it the rank of
a sub-order rather than a family.1

1 The classification of Labbe [4] is founded upon the number of uninucleate
masses or archispores into which the schizout or sporont divides up in the first
instance. In Eimeria each archispore becomes a sporozoite ; in other forms each
archispore becomes a sporoblast which secretes the sporocyst, and then may further
divide up to form sporozoites. On this basis of division Labbe founds two sub-orders
— I. Polyplastina, with numerous archispores (Eimeria, Klossia, Adelea, etc.) ; II.
Oligoplastina, with few (2-4) archispores (Coccidium, Diplosp&ra, etc.).

Lt'-ger [47] considers that the primary subdivision of the Coccidia should be
based upon the number of sporozoites formed in each oocyst. He therefore classifies
them as follows : —

A. Coccidia with polyzoic oocysts, including (1) Aspvrocystidae (Eimeria), with
no sporocysts ; and (2) I'olysporocystidae, with sporocysts, which are monozoic
(Barroitssia), dizoic (Adelea), trizoic (Benedenia), or tetrazoic (Klossia).

B. Coccidia with octozoic oocysts, including (1) Disporocystidae, with two tetrazoic
sporocysts (I)iplospora) ; and (2) Tetrasporocystidae, with four dizoic sporocysts
( Coccidium, C'rystallospora).

C. Coccidia with tetrazoic oocysts, including one genus (and family ?) Cyclospora,
with two dizoic sporocysts.

Mesnil [49], on the other hand, divides the Coccidia into two divisions, the
Asporocystea and the Sporocystea. The Asporocystea are to include the Asporo-
blastease« Monosporoblastea, for the species Leyerel/a (Eimeria) nova, andtheSporo-
lilastea, for the malarial parasites. The Sporocystea are the ordinary Coccidia.

It should be noted that the four families of Coccidia now generally recognised are
not named in accordance with the accepted rules of zoological nomenclature, which
require that a family should be named from its type-genus. Thus the Asporocystidae

230 THE SPOROZOA

FAMILY 1. ASPOROCYSTIDAE, Leger (Tribe Monosporea, A. Schneider).
No sporocysts are formed within the oocyst ; the sporozoites are naked
(gymnospores).

Genus 1. Eimeria, A. Schn., 1875 (Legerella, Mesnil, 1900). With
the characters of the family.

The genus Eimeria was founded by Aime Schneider for the
Gregarina falciformis described by Eimer (1870) from the intestine
of the mouse. The diagnostic generic character was the absence of
sporocysts. Several other species were afterwards added by Schneider
and others to the genus. The rapid advances that have been
made within recent years in our knowledge of the life - histories of
Coccidia have shown that nearly all the species of Eimeria are nothing
but the schizogonous generations of Coccidia belonging to other genera
and species. Thus the type species, E. falciformis of the mouse, becomes
Coccidium falciforme ; E. schneideri, Butschli, from Lithobius, is the
schizont of Adelea ovata ; while E. schneideri, Schneider non Butschli,
appears to be that of Coccidium lacazei (Labbd). E. nepae is probably
identical in like manner with Barrowssia ornata from the same host. In
the light of these facts, it appeared, until recently, extremely probable
that the name Eimeria was about to become a women nudum, a fate which
has already overtaken the " Eimerian " genera Pfeifferia seu Pfeifferella,
Labbe" ; Karyophagus, Steinhaus ; Cytophagus, Steinhaus ; Acystis, Labbe
(founded to include the two foregoing) ; Gonobia, Mingazzini ; Molybdis,
Pachinger ; and Cretya, Mingazzini.

Quite recently, however, it has been discovered by Le*ger [47] and
Bonnet-Eymard [31] that one species, at least, of Eimeria has claims to
independent recognition. E. nova, A. Schn., from the Malpighian tubules
of Glomeris has been thought to be the Eimerian stage of Cyclospora
glomericola, A. Schn., from the same host ; but Glomeris guttata in Provence,
and G. ornata in the Dauphin e, are infected with the Eimeria, but not
with the Cyclospora. Examination of the Eimeria shows further that it
has a typical alternation of generations ; schizogony, with differentiated
male and female schizonts, as in Adelea ovata, is followed by sporogony,
with the formation of a zygote which breaks up within a resistent oocyst
into thirty or forty naked sporozoites, arranged side by side, or in a
twisted bundle.

Eimeria nova remains, therefore, an independent species, the only
one 1 at present contained in the genus after subtraction of those which
are merely schizonts of other species. The true Eimeria is easily
distinguished from the false by the fact that its naked sporozoites are
enclosed in a resistent oocyst, whereas in schizogony there is no cyst-
envelope of any sort enclosing the merozoites.

should be Eimeridae (or Leger ell idae) ; the Disporocystidae should be Isosporidae ;
the Tetrasporocystidae should be Coccididae (or Eiineridae) ; and the Polysporo-
cystidae should be Klossidae.

1 Since this was written Cuenot [32] has described another species of Eimeria,
under the name Legerella testiculi, which is parasitic in the testis of Glomeris mar-
ginata, and therefore occurs only in one sex of the host. In this form precocious
association occurs between a macrogametocyte and one or two microgametocytes,
as in Adelea ovata.

THE SPOROZOA

231

Mesnil has proposed, however, the new generic name Legerella for
Eimeria nova, on the ground that the use of the name Eimeria is incon-
venient now that all the other species have been found to be simply
schizogonous stages. Experts learned in the laws of zoological nomen-
clature may decide how far such a course is justifiable and proper.1

FAMILY 2. DISPOROCTSTIDAE, Leger (Tribe Disporea, A. Schneider).
The oocyst contains two spores (chlamydospores).

Genus 2. Cyclospora, A. Schn., 1881. Spores dizoic.

Fio. 59.

Sporogony of Cyclospora glomericola, A. Schn. (par. Glomeris). a, oocyst freshly encysted. 6,
the contents of the oocyst have contracted, and a partition is formed at each end. c, d, e, forma-
tion of the two sporoblasts. /, the sporoblasts developing into spores, g, oocyst with ripe
spores, h, spore more highly magnified, showing the two sporozoites and the sporal residuum.
From Wasielewski, after A. Schneider.

The type -species is G. glomericola, A. Schn., from the intestinal
epithelium of Glomeris. Very recently Schaudinn [5 la] has described
in great detail the life-cycle of another species, C. caryolytica, Schaud.,
which occurs as an intra-
nuclear parasite of the
intestinal epithelium of the
mole.

Genus 3. Diplospora,
Labbe", 1893. Spores tetra-
zoic.

Type-species, D. lacazei,
Labb£ (including!). rivoltae,
Labbe), from a great num-
ber of birds. Others are D.
cammillerii, Hagenm., from
the lizard Gongylus ocellatus;
D. mesnili, Sergent [516]
from Chamaeleo vulgaris ;
and D. laverani, Hagenm.,
from the snake Coelopeltis Cysts of Diplospora lieterkuhni (Labbe), (par. Sana
lareriina both orrnrrino- in esmlenta). a, cyst with two sporoblasts, each with two

mna, DI ing in chromatin masses (chr). b, cyst with two ripe spores,

Algeria. D. lieberkiihni each containing four sporozoites (sp.z) and a sporal resi-

n i , ,-. /T-,. „„,. . duum(sp.r). After Laveran and Mesnil [40], X 1000.

(Labbe) (Fig. 60), occurring

in the kidneys of Rana esculenta (where it was first noted by Lieberkuhn

in 1854), has been made by Labbe the type of his genus Hyaloklossia

1 Stiles [59] has recently proposed the name Eimeriella, as a substitute for
Eimeria, on the ground that the latter name belongs, by right of priority, to the
genus commonly known as Coccidium (see below, p. 232, footnote).

Fio. 60.

232

THE SPOROZOA

(vide infra, p. 236). The reproduction of D. lacazei has been studied by
Laveran. By many authors this genus is united with the following.1
Genus 4. Isospcra, A. Schn., 1881. Spores polyzoic.
I. ram, A. Schn., from the black slug Limax cimreo-niger (kidneys?),
characterised by having numerous sporozoites in each
spore (Fig. 61).

FAMILY 3. TETRASPOROCYSTIDAE, Leger (Tribe Tetra-
sporea, A. Schn.). The oocyst contains four spores
(chlamydospores).

Genus 5. Coccidium, Leuckart, 1879. The dizoic
spores are spherical or ovaL

A very large number of species, confined, with few
exceptions (see p. 206), to Vertebrate hosts, and occur-
Limax sp.), show- ring commonly in all kinds of Vertebrates. The type
z"fc spore!0 From an(l best - known species is the common C. oviforme,
Leuck-'2 from tlie rabbit (Figs. 47 and 62), which is said
to be found occasionally also in man (see reference on p.
209). In Sauropsida the prevailing type is Diplospora (see above), but

FIG. 61.

FIG. 62.

Spore formation in Coccidium oviforme, Leuck., from the liver of the rabbit. After Balbiani,
from Wasielewski. a, encysted individual (zygote) in which the protoplasm is beginning to
shrink away from the oval oocyst at the two poles. 6, the zygote has contracted itself into a
spherical form, c, segmentation into four sporoblasts. d, elongation of the sporoblasts to
form spores, e, four complete spores in the oocyst. /, single spore more highly magnified,
showing the two sporozoites and a small quantity of residual protoplasm.

Coccidium raillieti, Le"ger, has been described from the intestine of the
slow-worm Anguis fragilis ; and C. delagei, Labbe, from that of the water-
tortoise Cistudo europaea ; while G. tenellum, Bailliet, with several varieties,

1 Laveran, Mesnil, Schaudinn, and Blan chard are apparently of opinion that
Schneider's description of Isospora rara as polyzoic was erroneous, and regard this
species as tetrazoic, thereby making the genera Isospora and Diplospora synonymous.
Hence, since Isospora is the older name, they make use of it for all the species here
termed Diplospora. But until Schneider's type of Isospora has been re-examined, it
is somewhat prematiire to assume that so experienced and distinguished an investi-
gator was in error in describing it as polyzoic.

2 But according to Labbe [4] the name Psorospermium cuniculi, Rivolta, 1878,
is prior to Coccidium oviforme, Leuckart, 1879 ; the correct designation of the
species would therefore be Coccidium cuniculi (Rivolta). According to Stiles [58],
on the other hand, the species was named Monocystis stiedae by Lindemann in 1865.
Since, moreover, the type-species of Eimeria (E. falciformis) has proved to be a
Coccidium, this author claims that Eimeria 1875, as a generic name, has priority over
Coccidium 1879. The conclusion is that Coccidium as a generic name should dis-
appear, and the Coccidian parasite of the rabbit's liver should be called Eimeria
stiedae (Lindemann). Liihe (48«) is of the same opinion as regards the application
and validity of the generic names Eimeria and Coccidium.

THE SPOROZOA

233

is found in birds. In mammals and in Ichthyopsida numerous species
are found.

Laveran and Mesnil [59] have recently described a species from the
intestine of the frog (Rana esculenta), in which the sporocysts, after being
formed in the usual manner, become redissolved, leaving the eight sporo-
zoites free in the cyst, thus bringing about secondarily a condition similar
to that which characterises the genus Eimeria. The authors consider this
form sufficiently distinct to be the type of a new subgenus, and name it
Paracoccidium prevoti (Fig. 63). Still more recently [40] these authors

Fio. 63.

Cysts of Paraeoccidium. prevoti, Lav. et Mesn.
(par. Rana esculenta). a, cyst with four spores and
a cystal residuum (c.r). Each spore contains two
sporozoites and a sporal residuum (sp.r). b, ripe
cyst in which the sporocysts have become dis-
solved, setting free their contents ; the cyst con-
tains eight sporozoites (sp.z), four sporal residua
(sp.r), and a cystal residuum (c.r). c.w, cyst-wall.
After Laveran and Mesnil [39], xlOOO.

have described a species of Coccidium from the rectum of the tortoise
Damonia reevesii, under the name of C. mitrarium, which is remarkable
for having oocysts shaped like a mitre, and is also unique amongst Coccidia
in being an extracellular parasite.

Genus 6. Crystallospora, Labbe, 1896. The dizoic spores have the
form of a double pyramid (Fig. 66, /).

Type-species, Crystallospora cnjstalloides (Thelohan), from the intestine
and pyloric caeca of Motella tricirrata of Eoscoff.

FAMILY 4. POLYSPOROCYSTIDAE, Leger (Tribe Polysporea, A. Schn.).
The oocyst contains numerous spores (chlamydospores).

Genus 7. Barroussia, A. Schn., 1885. The monozoic spores are
spherical, with smooth bivalve shell (sporocyst).

B. ornata, A. Schn., type-species, from the gut of Nepa cinerea (Fig.
64) ; B. schneideri, Leger, from the gut of Lithobius impressus ; B. caudata,
Le"ger, from the gut of Lithobius martini, is referred by Labbe" to Minchinia.

Genus 8. Echinospora, Le"ger, 1897. The monozoic spores are oval,
the bivalve sporocyst is spiny (Fig. 66, c).

Type -species, E. labbei, Leger, from the gut of Lithobius mutabilis.
By Schaudinn and others this genus is united with the foregoing.

Genus 9. Diaspora, Ldger, 1898. The monozoic spores are oval, the
eporocysts are not bivalve, and have a micropyle at one pole (Fig. 66, 6).

Type-species, D. hydatidea, Leger, from the intestine of the myriapod
Polydesmus, in Provence.

By Schaudinn this genus is united with Barroussia,

Genus 10. Adelea, A. Schn., 1875. The dizoic spores are spherical
or compressed, with smooth sporocysts (Fig. 65).

Type-species, A. ovata, A. Schn. (see p. 223, Figs. 55 and 56) ; others
are A. mesnili, Perez (see p. 206, footnote) ; A. akidium, Le"ger; A. tipulae,
Leger ; A. dimidiata (A. Schn.), from the gut of Scolopendra morsitans
(Fig. 65) ; and A. simplex (A. Schn.), from the gut of the larva of Gyrinus.

234

THE SPOROZOA

Genus 11. Minchinia, Labbe', 1896. The dizoic spores are oval, the
sporocysts produced at each pole into two long filaments (Fig. 66, a).

Type-species, M. chitonis (E. R. L.), discovered by Lankester in the liver
of Chiton. Allied species, not named, occur in a similar situation in
Patella, and Trochus (Labbe".) By Schaudinn this genus is united with
Adelea.

FIG. 64.

Sporogony and spore-germination in Barrmissia ornata, A. Schn.,
from the gut of A'epa cinerea. a, oocyst with sporoblasts. 6,
oocyst with ripe spores, c, a spore highly magnified, showing the
single sporozoite bent on itself, d, the spore has split along
its outer coat or epispore, but the sporozoite is still enclosed in
the endospore. e, the sporozoite, freed from the endospore, is
emerging. /, the sporozoite has straightened itself out and is
freed from its envelopes. From Wasielewski, after A. Schneider.

Genus 12. " Benedenia," A. Schn., 1875 (Legeria, Blanchard, 1900 ;
Eucoccidium, Liihe, 1902). The spherical spores are trizoic. No
schizogony.

Type-species, " B. " eberthi (Labbe"), from the epithelium of the gut and
other organs of Sepia l (Fig. 58).

1 The correct name of this species, commonly cited as Benedenia octopiana, A.
Schn., is far from being settled. In the first place, as regards the generic name,

THE SPOROZOA

235

Genus 13. Klossia, A. Schn., 1875. The spherical spores are
tetrazoic or polyzoic.1

FIG. 65.

Sporogony of Adelea dimidiata, A. Schn. (par. Scolopendra morsitans). a, sporpnt encysted
in a host -cell, and commencing to divide, b, the contents of the oocyst have divided into a
number of sporoblasts. c, oocyst containing ripe spores, d, a ripe spore more highly
magnified, showing the two sporocysts and the granular residual body. From Wasielewski,
after A. Schneider.

The type-species is K. helicina, A. Schn. (Fig. 48), infesting the kidneys
of various land-snails (Helix spp., Succmea spp.). The parasite and its life-
many authors place the species in the genus Klossia. Assuming, however, that the
trizoic condition is an adequate generic difference, the name Eenedenia must never-
theless be changed on the ground of preoccupation, having been employed by Diesing
in 1858 for a Trematode. Blanchard has proposed in its place the generic name
Legeria (1900), but Labbe had already (1899) given this name to the genus of
Gregariues previously termed Du.fouria (see p. 200). As regards the specific name,
Labbe terms the trizoic species, occurring in Sepia, Klossia eberthi, and retains the
specific name octopiana of Schneider for a polyzoic species of Klossia occurring in
Octopus. If two distinct species, inhabiting different hosts, were originally confused
by Schneider under one name, this is certainly a useful reform.

Very recently Liihe [48a] has proposed the name Eucoccidium for Benedenia.
He regards the name Coccidium as obsolete (see above p. 232, footnote), having been
given to the sporogonous cycle of Eimeria. Since, therefore, "Benedenia " has only
sporogony, he considers the name Eucoccidium appropriate to denote such a form.
Liihe retains, however, the specific name octopianum, which is inappropriate if, as
alleged, the species occurs in Sepia and not in Octopus.

1 Mesnil [6] considers the genus Klossia to be normally tetrazoic, and states that
in K. helicina the usual number of sporozoites is four, though it may exceptionally
be as high as eight. He also throws doubt upon the alleged occurrence of 10-12
sporozoites in the spore of K. octopiana.

236

THE SPOROZOA

history were figured and described by Kloss in 1855, but not named by
him — the first thorough account of any Coccidian. The spores contain
five or six sporozoites. K, soror, A. Schn., from the kidney of the water-
snail Neritina flumatilis, is tetrazoic. K. octopiana (A. Schn.), Labbe,
from the intestine of Octopus and Eledone, has ten to twelve sporozoites in
the spore.

Genus 14. Caryotropha, Siedlecki, 1902. The spherical spores,
about twenty in number, contain each twelve sporozoites. Unique
species, C. mesnilii, Siedl. (Fig. 67), parasite of the clusters of spermato-
gonia of Polymnia nebulosa. Bemarkable for its habitat, this species also
shows some interesting peculiarities in its developmental phases (see
pp. 223 and 225).

Genus 15. Klossiella, Smith and Johnstone, 1902. The subspherical
spores are polyzoic and contain from thirty to thirty-four sporozoites.

Spores of various Coccidian genera, a, Minchinia chitonis (E. R. L.), (par. Cliiton) ; fe, Diaspora
hydatidea, Leger (par. Polydesimis) ; c, Echinospora labbei, Leger (par. Lithobius mutabilis) ; d,
Goussia motellae, Labbe ; e, Diplospora (Hyaloldossia) lieberkiitini (Labbe), (par. Rana esailenta) ;
f, Crystallospora crystalloides (Thel.), (par. Motella tricirrata). 6 and c after Leger, the others
after Labb6.

Unique species, K. muris, Sm. and Jnst., from the kidney of the
mouse. The sporogonic cycle is found in the epithelium of the con-
voluted tubules. Another form, representing the schizogonic cycle,
apparently, is found in the glomeruli. The very large number of
sporozoites is a remarkable feature of this species.

Doubtful genera are : —

Hyaloldossia, Labbe, 1896, characterised by polysporous oocysts with
oval spores which are either dizoic or tetrazoic. The type - species,
H. lieberkuhni (Labbe), from the kidney of Rana esculenta, has been
found, however, by Laveran and Mesnil [40] to be a Diplospora (vide
ante, p. 231) ; but another species, H. pelseneeri, Le"ger, is described from
the kidney of Tellina, which appears to conform to Labbe"'s generic
definition, although the latter was founded on a mistaken observation.

Goussia, Labbe, 1896, which differs from Coccidium by its bivalve
spores (Fig. 66, d), opening like a pea-pod (Gallice gousse). The genus, as
thus characterised, includes, according to Labbe, eight species, all infesting

THE SPOROZOA

237

the intestine or liver of various fishes. By other authors the genus is
united with Coccidium.

Bananella, Labbe, 1895, founded for B. lacazei, Labbe, from Lithobius,

f

Phases of Caryotropha mefnilii, Siedl. (par. Polymnia nebulosa). a, young schizont in a
cluster of spermatogonia ; the host-cell (represented granulated) and two of its neighbours are
greatly hypertropliied, with very large nuclei, and have fused into a single mass containing the
parasite (represented clear, with a thick outline). The other spermatogonia are normal. " 6,
full-grown schizont enclosed in the hypertrophied host-cell, with an enormous nucleus, which
appears to be connected with the nucleus of the parasite by a band of granules, c, intra-
cellular .schizont divided up into schizontocytes. rf, each schizontocyte giving rise to a cluster
of merozoites arrangnd as a "corps en barillet." e, intracellular microgametocyte divided into
microgametocytes of the second order, each of which is forming numerous microgametes. /,
niicroganietes in front and side view, spy, spermatogonia; h.c, host-cell; AT, nucleus of host-
cell or cells ; n, nucleus of parasite ; «•«, schizontocyte ; tnz, merozoites ; mgc, microgametocytes
of the second order ; my, microgametes.

238 THE SPOROZOA

and characterised, according to its founder, by forming three, exception-
ally four, spores ; hence made the type of a tribe Trisporea. Schaudinn,
Blanchard, and others regard the trisporous condition as an anomaly, and
place the species under Coccidium.

Rhabdospora, Laguesse, 1895 ; Gonobia, Mingazzini, 1892 ; Pfeifferella,
Labbe, 1899 ; Molybdis, Pachinger, 1886 ; Cretya, Mingazzini, 1892 ;
and perhaps also Gymnospora, Moniez, 1886, probably all of which
represent the schizogonous generations of species of Coccidium and
other genera. For full details concerning them the reader is referred
to Labbe" [4].

Branchiocystis, Burchardt, 1900 (Jen. Zeitschr. f. Nat. vsiss. 34, pp.
779-784, pi. xix. figs. 9-11, and xx. figs. 1-9), a genus founded for
B. amphioxi, a " Coccidium " parasitic on the epithelium of the gill-
bars of Amphioxus. It was found to be seldom absent in Amphioxus
material from Naples and Messina, and often occurred in abundance,
affecting especially the gill-bars at the level of the apex of the liver.
The parasite appears as a rounded or oval body, 10-14 p in diameter,
lodged in the flagellated epithelium of the broad sides of the gill-bars.
Some of these bodies appear homogeneous, without nucleus (?) ; others con-
tain a number of oval or rounded " sporoblasts," 2-2'5 //, in diameter,
which become sausage-shaped bodies.

It is difficult to see why the author should consider Branchiocystis a
Coccidian. The description does not render it possible to place it near
any of the recognised genera of Coccidia. The figures given remind one
more of the Glugeidae amongst Myxosporidia than of any true Coccidian,
and it is perhaps in or near the genus Pleistophora (p. 297) that this
parasite would be correctly placed.

Coccidioides, Kixford and Gilchrist, 1897, for C. immitis, R. and G., a
problematic organism occurring as a parasite of man, and up to the
present observed only in America. The infection, or rather contagion,
is acquired by the skin, whence the parasites spread into the lymphatics
and invade other organs. The malady caused by the parasite may be
chronic or acute, and in the latter condition it is fatal in a short time.
The characteristics of the disease are very similar to those of miliary
tuberculosis, an immense number of minute nodules being formed in all
the viscera. In each nodule one or two parasites are found, either free
or lodged in a giant cell. The parasites have the form of "rounded
protoplasmic masses, 20, 50, 60, or 80 p in breadth, surrounded by a
thick enveloping membrane. Their multiplication ... is effected by a
series of bipartitions which go on within the membrane. The latter then
bursts and sets free the young parasitic elements, which grow in situ,
or are carried away by the blood or lymph " (Blanchard). Several
forms of the parasite have been described, and have even received di^-
tinct names. A full account of them will be found in Blanchard [30],
who considers that they are Sporozoa, but not to be included in the order
Coccidiidea.

THE SPOROZOA 239

ORDER 3. Haemosporidia.

The Haemosporidia are a group of Sporozoa adapted to a very
special mode of parasitism, and therefore limited in habitat and
occurrence. They exhibit, however, an interesting range of
variations, both in morphological structure and in adaptation to
their special life -conditions. Their distinctive features are as
follows. They are parasitic usually upon the red blood-corpuscles,
sometimes also upon other cells, of Vertebrata. The trophozoite is
endoglobular, i.e. intracellular, in situation, and may remain so
throughout the whole trophic period, or may quit the host-cell
and become free in the blood-plasma after reaching a certain stage
of growth. The endoglobular forms are very commonly amoeboid,
but those which become free have definite body-contours, and
resemble tiny gregarines of elongated form and worm-like appear-
ance, which when liberated from the blood-corpuscle are actively
motile. The life-cycle shows an alternation of generations similar
to that occurring in Coccidia. In all cases, probably, non-sexual
reproduction by means of schizogony continued through many
generations serves to multiply the parasites within the host, and
is then followed by the formation of gametes, which conjugate to
produce zygotes or sporonts. Each sporont is at first motile, and
seeks out a suitable position in which to become encysted as an
oocyst. It then undergoes sporogony to form a number of minute
germs, which are always naked gymnospores or sporozoites, never
enclosed in sporocysts. In many forms, perhaps in all those
parasitic upon warm-blooded animals, the entire sexual cycle takes
place in an intermediate host, an invertebrate animal of blood-
sucking habits, upon which the sporont is actively parasitic, and
by which fresh vertebrate hosts are inoculated with the germs of
the parasite.

Our scientific knowledge of the Haemosporidia is of extremely recent
date, and begins with the discovery, by Lankester, in 1871, of the
parasite of the frog's blood, which in 1882 he named Drepanidium
( = Larikesterelki) ranarum, and recognised as a member of the Sporozoa.
At the latter date Laveran, then a military doctor at Constantin in
Algiers, discovered the malarial parasite in human blood. He described
all its characteristic stages — amoebula, rosette, crescent, sphere, and
flagellated body — and saw in it the cause of the disease, but it was many
years before his ideas became generally accepted. Laveran did not at
first recognise the true nature of the parasite he had discovered, but
regarded it as a vegetable organism and named it Oscillaria malariae.
Metschnikoff was the first to place it amongst the Sporozoa, under the
generic designation Haematophyllum (1887); it had already, however,
been named Plasmodium by Marchiafava and Celli in 1885. Our know-
ledge of these organisms was further advanced by the studies of Danilewsky,

240 THE SPOROZOA

who gave them as a class the name Haemosporidia or Haemocytozoa, and
by other investigators. In 1894 Labbe brought forward detailed and
extended researches upon these parasites, and described many new forms.
The concluding years of the nineteenth century have brought a very rapid
increase in our knowledge of the malarial parasites, and the labours of
Ross, Grassi, and many others have revealed their complete life-history, a
chapter of biology of the greatest practical importance as well as of scientific
interest. At present it is amongst the Haemosporidia of cold-blooded
Vertebrata that researches are most needed.

(a) Occurrence and Habitat. — The Haemosporidia are found com-
monly as blood -parasites in mammals, in birds, and in all the
existing orders of reptiles, except perhaps the Rhynchocephala.
Amongst amphibia they appear to occur abundantly in the frog,
at least, which has been credited with harbouring no less than five
species, distributed amongst four genera, of these parasites ; but it
is highly probable that improved knowledge will bring about
reductions in this list. From Urodela, on the other hand, only
doubtful species have been recorded. In fishes also Haemosporidia
were generally considered to be conspicuous by their absence, but
very recently Laveran and Mesnil [79, 79a] have described species
infesting rays, soles, and blennies respectively. If we except the
cases where a part of the life-cycle is passed through in an inter-
mediate host, there is no record of their occurrence in Invertebrates,
with the exception of one very doubtful species (Haemogregarina
nasuta, Eisen) stated to occur in the walls of the blood-vessels
and the mesentery of an Annelid (Eclipidrilus frigidus).

The principal habitat of Haemosporidia is the red blood-
corpuscles of their hosts, but they may be found also in the
leucocytes, and in the cells of certain organs, especially the
spleen and bone -marrow. It is not uncommon for the repro-
ductive phases of the parasite in the vertebrate body to be rare
or absent in the blood of the peripheral circulation, in which only
growing trophozoites or gametocytes are to be found, while the
"rosettes" and other stages of schizogony occur only in the more
slowly flowing blood of the brain, liver, kidney, and other viscera.
The situation of the endoglobular parasite is always within the blood-
corpuscle or cell it attacks,1 and not, as supposed originally by
Laveran, merely one of attachment to the corpuscles. In the case
of the forms parasitic upon Vertebrata other than mammals, the
nucleus of the haematid is often displaced by the parasite, proving
clearly its internal position. Occasionally the nucleus itself may
be attacked ; a good example of this is seen in the form parasitic

1 The view of Laveran that the parasites are attached (" accoles ") to the cor-
puscle has recently been revived and supported by Argtitinsky [61, 1901], but his
statements have been criticised and contradicted by Schaudinn [94a], who is strongly
in favour of the view put forward above.

THE SPOROZOA 241

upon various species of Lacerta, whichx-from its effects upon the
nucleus of the host-cell has been termed Karyolysiis lacertarum. In
blood -corpuscles infected with Karyolysus, the nucleus becomes
hypertrophied and divides amitotically into two or more fragments,
which ultimately degenerate (Fig. 76).

In the sub-order Acystosporea the parasite retains the endo-
globular or intracellular situation throughout the whole endo-
genous generation, except for the brief period during which the
merozoites are seeking fresh corpuscles to attack. But in the
sub-order Haemosporea the parasite leaves its first host-cell and
becomes free in the blood -plasma. It then penetrates other
corpuscles, Avhich it may abandon again, but as a rule it comes to
rest finally within a corpuscle or cell, and undergoes schizogony
in this situation, though sometimes even the reproductive stages
may be free in the spleen-pulp or bone-marrow.

The effects produced by Haemosporidia upon their hosts seem
to differ markedly in the case of cold-blooded and warm-blooded
animals. In the former there is no evidence that these parasites,
however numerous, produce any pathological effect upon their
hosts at all. But in birds and mammals they cause fevers and
agues of various kinds, of which those that trouble the human species
are naturally the best known. The varieties of malarial fevers and
their symptoms will be found described in medical treatises, but a
few points may be briefly summarised here. At least three types
of fever are generally recognised, each caused by a distinct form
of parasite (see below, p. 243) — the two so-called benign inter-
mittent fevers, tertian and quartan ague, and the pernicious
aestivo- autumnal fever or tropical malaria. In each case the
parasite is introduced into the human body by the bite of a
mosquito, and not, so far as is known, in any other way. After
a period of incubation, varying from six to twelve days, according
to the species of parasite, the fever makes its appearance. In
the benign forms the feverish symptoms appear at regular
intervals, dependent on the time occupied by a complete repro-
ductive cycle of the parasite. Thus in the parasite of tertian
ague the schizogony takes forty-eight hours, and the fever recurs
every other day. In quartan ague the schizogony takes seventy-
two hours, and the attacks of fever recur once every three days.
There may, however, be double or triple infections, the result of
distinct inoculations ; or again there may be mixed infections of
the two forms, so that distinct generations of the parasites occur
contemporaneously in a given patient, producing every possible
variation in the frequency of the attacks of fever. In pernicious
malaria, on the other hand, the sporulation takes place irregularly,
and the fever is consequently irregular or continuous in its
manifestations. In all cases the fever coincides in its appearance

16

242 THE SPOROZOA

with the actual sporulation of the parasite, when vast numbers of
merozoites are set free in the blood, and are attacking fresh,
healthy corpuscles. The result of the rapid multiplication of the
parasite in the blood, and the consequent destruction of the
corpuscles, is a condition of anaemia which tends to produce
general cachexy, and may terminate fatally. At the same time
the melanin-granules produced by the parasite, and dispersed in
the blood when the sheltering corpuscle disintegrates and the
merozoites scatter (see below, p. 245), become deposited in the
spleen and liver, which become hypertrophied, and also in the
lungs, kidneys, and brain, causing a pigmentation of these organs.
In pernicious malaria death may ensue from the accumulation of
the parasites in the capillaries of the brain to such an extent
that the circulation is hindered or completely blocked. Finally, it
should be mentioned that the fevers may be acute or chronic, and
that in the latter condition the disease may be masked or latent
for a considerable period. What exactly happens to the parasite
during this time is now the only obscure part of its life-history.

Fevers similar to malaria appear to be produced in birds and
in various mammals by Haemosporidian parasites. In birds,
according to Macallum [84], characteristic changes take place in the
internal organs, resulting from the destruction of blood-corpuscles
and the deposition of pigment. The spleen and liver are the
parts chiefly affected ; the bone-marrow and other organs less so.
In cattle an acute and rapidly fatal disease, the so-called Texas-
fever (" Tick-fever," " Tristeza," " Redwater," etc.), is produced by
Piroplasma bigeminum, manifesting itself in high body-temperature,
loss of appetite, and jaundice of the sclerotics, accompanied by
general dulness and emaciation, and in many, though not in all
cases, by pronounced haemoglobinuria, the urine being the colour
of port-wine. In horses a fever similar to malaria is produced by
Piroplasma equi, and in dogs Piroplasma canis is the cause of the so-
called "malignant jaundice," very similar in its symptoms to Texas-
fever in cattle. Interesting discoveries with regard to the life-
histories of these parasites are probably to be expected in the near
future.

(b) Morphology and Life-history. — The forms that have been
most fully worked out, and of which the life-histories are best
known, are those infesting the human blood. They may there-
fore serve as types of the structural and developmental character-
istics of the whole order, and the distinctive features of other
forms will be described briefly afterwards.

It is still a matter of controversy how many species of these
parasites occur in the blood of man. Their discoverer, Laveran,
regards them all as one species ; some authorities, on the other
hand, believe in the existence of as many as five different kinds.

THE SPOROZOA 243

The majority of experts, however, are agreed in recognising three
distinct species, divided amongst two different genera.1 These
are (1) Laverania malariae, Gr. et Fel., the parasite of pernicious
malaria ; (2) Plasmodium malariae (Lav.), the parasite of quartan
ague ; and (3) Plasmodium vivax (Gr. et Fel.), the parasite of
tertian ague. The following account refers more especially to
the first of these, but the peculiarities which characterise the
other two will be briefly mentioned by way of comparison.2

The minute sporozoites, introduced into the human blood by
the bite of a mosquito, attack and penetrate red blood-corpuscles,
probably in a way similar to the infection of epithelial cells by
Coccidian parasites. Each sporozoite (" exotospore," Lankester) 3
is slender, almost filamentous in form, the body sharply pointed
at each end, with a thicker central portion in which the nucleus is
lodged (Fig. 68, XIX). Within the blood-corpuscle the sporozoite
rounds itself off and develops into an amoeboid trophozoite, which
grows at the expense of the blood-corpuscle until it nearly fills
it (Fig. 68, I-V). The youngest amoebulae are without any pig-
ment, but usually contain, in fixed and stained preparations,
a conspicuous vacuole, giving the parasite the so-called ring-form.
With further growth the vacuole disappears, and grains of pig-
ment termed melanin, representing, probably, an excretory product,
are formed in the body of the parasite and collect towards the
centre near the nucleus. When full-grown the trophozoite acquires
a rounded form and is now a ripe schizont (" sporulating body,"
" sporocyte "), ready to reproduce itself by schizogony (Fig. 68,
6). The nucleus divides to form a variable number of daughter
nuclei, which travel to the periphery (Fig. 68, 7, 8). The proto-
plasmic body becomes divided up into a corresponding number of
segments, the merozoites (" enhaemospores," Lankester), centred
round a small mass of residuary protoplasm, in which all the pig-
ment-granules are deposited (Fig. 68, 9). This characteristic form
of the parasite, known as the rosette-stage ("corps en rosace"),
corresponds to the so-called " Eimerian cysts " of the Coccidia.
When the schizogony is complete, or, it may be, during the initial
stages of this process, the exhausted blood-corpuscle breaks up,

1 See also footnote to p. 267.

2 Since the account here given of the life-cycle of the malarial parasites was
written, the very important monograph of Schaudinn [94«] upon the tertian parasite
has come to hand, just as the proofs of this article are going to be paged. It is there-
fore, unfortunately, not possible to introduce any of Schaudinn's figures ; but had his
memoir appeared earlier, some portions of Fig. 68 might have been made less
diagrammatic.

3 Numerous terminologies have been suggested, and are in use, for the phases of
the malarial parasite ; the most recent is that suggested by Laukester, in Mature, vol.
Ixv. No. 1691 (27th March 1902). The scientific terminology of Schaudinn, already
introduced above for the Coccidia, is employed here, but reference is also made to
other names applicable specially to the various stages of the malarial parasites.

244

THE SPOROZOA

VI

FIG. 68.

THE SPOROZOA 245

and the merozoites are set free in the blood-plasma (Fig. 68, 10),
abandoning the residuary protoplasm, which becomes disintegrated,
scattering its contained pigment. The merozoites behave as did
the sporozoites from which they are descended ; that is to say,
they attack and penetrate fresh blood-corpuscles, and develop in
their turn into schizonts which produce fresh generations of mero-
zoites over again by the method of schizogony.

The endogenous cycle is similar in all essential features in the three
species of the parasites of man, but each of them has its own distinctive
characteristics. The amoeboid movement is most active, and continues
longest, in Plasmodium vivax, most sluggish in P. malariae. In Laverania
the movements are very lively in the youngest, unpigmented stage. In

Diagram of the complete life-cycle of the parasite of pernicious malaria, Laverania tnalariae,
Gr. et Fel. The stages on the upper side of the dotted line are those found in human blood ;
below the dotted line are seen the phases through which the parasite passes in the intermediate
host, the mosquito. I-V and 6-10 show the schizogony. VI-XII, the sexual generation, which
at VII splits into two lines (a) male and (b) female, to be united again by conjugation (XI
and XII). XIII, the motile zygote. XIV-XIX, sporogouy. I-III, young amoebulae in
blood-corpuscles, the two last showing the ring-form (which is, however, not quite correctly
drawn ; see p. 246). IV, older, actively amoeboid trophozoite. y, still older, less amoeboid
trophozoite. 0, mature schizont. 7, schizont with nucleus dividing up. 8, young rosette
stage. 9, fully -formed rosette stage; merozoites round a central residual mass of proto-
plasm containing the pigment, and blood - corpuscle beginning to break down. 10, mero-
zoites free in the blood by breaking down of the corpuscle. VI, young indifferent gametocyte.
Vila, male crescent. VII6, female crescent. VIII « and b, the gametocytes becoming
oval. IX ft and b, spherical gametocytes ; in the male (IX a) the nucleus has divided up.
X a and b, formation of gametes ; in the male (X«) the so-called flagella or male gametes (fl)
are thrown out, one of them is seen detached ; in the female (X6), a portion of the nucleus has
been thrown oiiu. XI, a male gamete penetrating a female gamete at a cone of reception formed
near the nucleus. XII, zygote with two pronuclei in proximity. XIII, zygote in the motile
stage (vermicule or ookinete). XIV, encysted zygote (oocyst). XV, commencing multiplication
of the nuclei in the oocyst. XVI, oocyst with numerous sporoblasts. XVII, commencing
formation of sporozoites ; the nucleus of each sporoblast has divided to form numerous nuclei,
each of which is growing out in a little tongue of protoplasm to become a sporozoite, but a few
nuclei remain behind as residual nuclei. XVIII, full-grown oocyst crammed with ripe sporo-
zoites; on one side the cyst has burst and the sj>oro7oites are escaping. XIX, free sporozoites,
showing their changes of form, n, nucleus of the parasite ; p, melanin pigment ; fl, " flagella " ;
sp.bl, sporoblasts ; r.n, residual nuclei ; r.p, residual protoplasm. (Chiefly after Neveu-Lemaire,
from whom the plan and arrangement of the different stages is borrowed, with slight modifica-
tions ; details of the figures arc founded on the figures of Grassi, Schaudinn (Leuckart's Zoolo-
gische Wandtafdri), Ross, and others.)

all they slow down as the parasite approaches its full size. They differ
markedly also in their effects on the blood-corpuscle. Those attacked
by Plasmodium malariae diminish in size but retain their normal colour.
Corpuscles attacked by P. vivax, on the contrary, increase considerably in
size and become paler. The effect produced by Laverania varies greatly ;
the corpuscle is sometimes increased, sometimes diminished in size, and
the colour may be lessened or heightened in tint.

Schaudinn [94«] has recently studied the very active movements of
the sporozoites, and has observed the penetration of blood-corpuscles by
them, and by merozoites, in the case of the tertian parasite. He finds
that, as in the Coccidia, the sporozoites perform movements of flexion and
of peristaltic or euglenoid contraction, and that in addition they have the
power of gliding rapidly forward, with formation of a trail of gelatinous
substance. All three varieties of movement go on at the same time. The
penetration of the corpuscle takes about three-quarters of an hour, more

246 THE SPOROZOA

or less, and is effected in a manner very similar to that described above
(p. 211) for Coccidia. The movements of the merozoites are similar to
those of the sporozoites, but less active, and they may also show feeble
amoeboid movements.

Opinions still differ considerably as to the true structure and
significance of the very characteristic ring -stage of the endoglobular
parasite. Some authorities regard it as truly ring-like in structure, the
result of the union of two horn-like outgrowths or pseudopodia. Amongst
recent writers this view is supported by Ewing [66]. But most
authorities consider the ring-like appearance as merely the optical section
of a vesicular structure. Even then it is far from clear whether the
vesicle is a vacuole or whether it is simply the enlarged nucleus, distended
by fluid nuclear sap and containing a relatively small quantity of
chromatin. The latter alternative is, according to Argutinsky [61, 1902]
and others, the true interpretation of this stage. Argutinsky considers,
however, the distended condition of the nucleus to be merely the artificial
result of unsuitable methods of preserving these parasites as microscopic
objects. He states that if blood-films are treated with fixatives before
being dried, nothing is seen of any " ring-forms," but the nucleus appears
as an even spherical mass of chromatin, not surrounded by any clear space
intervening between it and the protoplasm of the body ; if, on the con-
trary, the blood-film be dried before fixation, according to the method of
procedure most commonly in vogue, the result is a deformation of the
tiny parasite, producing the ring-like appearance. On the other hand,
Schaudinn [94a] gives a very different account of the ring-form in the
case of the tertian parasite. He finds that it does not occur in the develop-
ment of the gametocytes, but that it is a constant stage in the growth
of the schizonts. In the latter case it appears in the youngest amoebulae
as a vacuole situated close to the nucleus. The vacuole grows rapidly in
size, causing the parasite to have the form of a signet-ring, as commonly
described, the nucleus being on one side of the ring. When the ring-
stage is fully developed it is difficult to say whether the vacuole is still
closed in, above and below, or whether the body does not become truly
ring-like. Schaudinn regards this vacuole as nutritive in function, con-
nected with the absorption of food-substance, and serving to increase the
body-surface of the parasite ; its appearance close to the nucleus supports
this interpretation ; and its presence in young schizonts, but not in young
gametocytes, is correlated with the fact that the former grow twice as fast
as the latter.

According to Billet [64], the endoglobular malarial parasite has
constantly at a certain stage of its growth an elongated form, coiled round
within the corpuscle. Billet terms this the Gregariniform stage, and
considers that it represents the haemogregarine phase of the Gymno-
sporidia. It remains to be seen to what extent such a stage is of constant
occurrence. According to Argutinsky's figures and descriptions [61, 1902]
of the tertian parasite, it frequently has " an elongated vermiform shape,"
which is to be regarded as merely one of the many forms which result
from its very great amoeboid activity, and this author shows that even the
nucleus shares, to a certain extent, in the changes of body-form. Schau-

THE SPOROZOA 247

dinn's detailed monograph [94a] of the tertian parasite contains nothing
to support Billet's view.

The schizogony is most easy to study in the two species of Plasmodium,
since in them it commonly takes place in the peripheral circulation, and
rosette - stages can be obtained in a drop of blood from the finger or
elsewhere. In Laverania, on the other hand, the sporulation goes on,
as a rule, in the internal organs, and its stages are difficult to obtain.
The multiplication of the nuclei in the schizont commences by a primitive
form of mitosis, but as the nuclei increase in number, the method of
division becomes a simpler type of multiple nuclear fission (Schaudinn
[94a]). The schizonts are distinguished by trifling differences of pigment-
ation in the three species, and also by variations in the process of
sporulation. In the quartan parasite the rosettes have a form which has
been compared to that of a daisy, and are relatively few, from nine to
twelve in number. In the tertian species the merozoites are more
numerous, usually from twelve to twenty -four in number, and the
corresponding stage has more the form of a mulberry. In Laverania the
forms of the rosettes, and the number of the merozoites in each, are very
variable. Most characteristic, however, is the length of time required
by each species to complete a generative cycle. In P. malanae a
schizogonous generation, from sporozoite (or inerozoite) to merozoite,
occupies seventy-two hours ; in P. vivax, forty-eight ; while in Laverania
it is twenty-four hours or of irregular duration.

By repeated schizogony the numbers of the parasites in the
blood increase by geometrical progression, in a way similar to the
Coccidia in an infected epithelium, until a very large number of
the corpuscles are infected and destroyed. Apparently the only
check to the multiplication of the parasite is to be found in the
activity of the leucocytes, which sometimes capture and destroy
a merozoite or other free stage. It is evident that reproduction
at this rate could only continue indefinitely in the ichor of an
infinite host. In the blood of an ordinary mortal of limited
capacities the results are most dangerous and even fatal.
Provision is therefore soon made for the transference of the
parasite to fresh hosts and new spheres of activity by the
development of certain merozoites into sexually differentiated
schizonts or gametocytes, the appearance of which is the
prelude, as in Coccidia, to reproduction by sporogony. In Laver-
ania the gametocytes are distinguished at once from ordinary
schizonts by their peculiar form, like that of a sausage, slightly
bowed, and considerably exceeding in length the diameter of the
blood-corpuscle, the remains of which are seen in the concavity of
the gametocyte (Fig. 68, Vila, VIK). Hence these forms of the
parasite, very characteristic of pernicious malaria, are commonly
known as " crescents." The gametocytes are not all alike, how-
ever, but can be separated into two categories, distinguished,
though not always very sharply, by the arrangement of the

248 THE SPOROZOA

pigment-granules. In the male crescents or microgametocytes
the grains of pigment are scattered evenly in the cell -body ;
in the female crescents or macrogametocytes the pigment is
aggregated at the centre, surrounding the nucleus. The crescents
appear to originate in the spleen and bone -marrow, but when
full-grown they are found in the peripheral circulation. As they
approach maturity the crescent -shaped gametocytes undergo a
change of form, becoming first oval, then spherical, and free
themselves in the final stage from the remains of the blood-
corpuscle (Fig. 68, VIII a and b, IX a and b). The changes from
crescent to sphere may take place in the human blood, or not
until transference to the intermediate host, the mosquito, has
been effected. In no case, however, do the gametocytes get
beyond the spherical stage in the human body.

The two species of Plasmodium are at once distinguishable from
Laverania by the fact that the gametocytes do not take on the form of
crescents, but have the same rounded shape as the ordinary schizonts.
The various forms of the tertian parasite have recently been studied in
great detail by Argutinsky [61] and Schaudinn [94a], whose results are,
in the main, in harmony. (1) The schizonts are about 10 fj. in diameter,
with a nucleus usually situated excentrically, and containing at first a
single mass of chromatin, later a number of chromatin granules held in
an even achromatic network, the whole being surrounded by a delicate
alveolar border (sic Schaudinn ; Argutinsky characterises the nucleus of
the schizont as vesicular). (2) The macrogametocytes are much larger
(12-16 /u, in diameter), when full-grown, than the schizonts, and much
less amoeboid during earlier stages of growth. Their protoplasm is
dense and stains deeply, and their grains of pigment are two or three
times as large, and fully twice as numerous, as those of the schizont.
The nucleus, situated at the periphery, is oval or elongated in form, with
grains of chromatin in the nodes of an alveolar framework. (3) The
microgametocytes are distinguished in all stages by their very large
chromatic nucleus, containing coarse grains of chromatin, and situated
centrally. The protoplasmic portion of the body is feebly developed as
compared with the two foregoing, and it is less dense and stains a much
lighter tint. It is scarcely at all amoeboid at any stage. The melanin-
pigment is abundant and the grains appear larger than in the macro-
gamete, but according to Schaudinn this is an optical illusion. Schaudinn
considers the differences between (2) and (3) to be adapted to their role
in development. The macrogamete, like an ovum, has to provide for
posterity, hence its large bulky protoplasmic body. In the microgameto-
cyte, only the nuclear substance passes on into the next generation, hence
the protoplasmic body is to a large extent atrophied, while the nucleus
is greatly developed.

The stages in the origin and growth of the gametocytes are still some-
what obscure. Mannaberg derived the crescent-form from a syzygy, i.e.
the union and fusion of two amoebulae, and more recently Ewing [66]
has maintained that unions of this kind take place between amoebulae.

THE SPOROZOA

249

The latter author describes the conjugation and fusion of ring-stages in
pairs within the blood-corpuscles. Wright [98] also supports the view that
the crescents arise from a syzygy of amoebulae within a doubly-infected
corpuscle. The analogy of the life-histories of other Haemosporidia or
Sporozoa affords no support to these statements, and the appearances upon
which they are based might equally well be interpreted as stages in the
fission of an amoebula or young gametocyte. Recently Schaudinn [94a]
has traced all stages in the development of the gametocytes of the tertian
parasite from the merozoites, so that the notion that the former arise
from fusions of amoebulae must be regarded as an exploded idea.

The intermediate host necessary for the propagation of the parasites
of malaria in man is a gnat or mosquito, belonging to the genus
Anopheles. Up to the present no other means of propagating the
disease has been discovered than through the agency of these insects.
If a human being suffering from malaria is bitten by an Anopheles

FIG. 69.

Anopheles clai'iger, Fabr. (After
Grassi.) X about 4.

FIG. 70.

Diagrams to show the positions assumed
when at rest by — a, Anopheles; b, Ovlex.
(After Neveu-Lemaire.)

mosquito (it is only the female gnats that suck blood), the mosquito
draws into its stomach various stages of the parasite along with the
blood. Young amoebulae, full-grown schizonts, rosettes, crescents, all
alike may be swallowed by the mosquito, but with different results. All
stages of the schizogonous cycle are digested in the mosquito's stomach
along with the blood corpuscles. The gametocytes alone are able to
resist the action of the digestive juices, and to continue their develop-
ment further. Freed from the last remnants of the blood-corpuscle in
which they grew up, they assume the spherical form, if they have not
already done so, and proceed to give rise to the gametes. The maturation
of the gametes and their subsequent conjugation take place in the
stomach of the mosquito.

The relation of the Haemosporidia to their intermediate hosts is one
of those finely-adjusted bionomical adaptations so frequently observed in
the life-histories of parasites. For if a malarial patient be bitten by a
mosquito of any other genus than Anopheles — by a species of Culex, for
example — then not only the schizonts, but also the gametocytes, are

250 THE SPOROZOA

digested by it. Culex, on the other hand, is the intermediary for
the Haemoproteus ( = Proteosomd) of birds, and when it bites a bird
infected with this genus of parasites, it digests all the stages except the
gametocytes. Culex, in fact, stands in the same relation to the malarial
parasites of birds, as Anopheles to those of man. Should an Anophelex,
on the other hand, bite a bird infected with Haemoproteufs, it will
digest every stage of the parasite, gametocytes and all.1

In the spherical microgametocyte ("sperm-mother-cell," Lan-
kester) the nucleus breaks up and the fragments of chromatin
travel to the periphery (Fig. 68, IXa). From Schaudinn's observa-
tions upon Haemoproteus it would appear that a karyosome is left in
the centre of the body, as in Coccidium. The surface of the body
grows out into long thread-like processes, usually four to six
in number, each extremely motile and resembling in its movements
a flagellum. Hence the parasite at this stage is known as the
Polymitus form, since it was regarded by some earlier observers as
a Flagellate belonging to that genus. The entire chromatin sub-
stance of the microgametocyte passes into the so-called flagella,
which are in reality the microgametes ("spermatozoa," Lankester).
They are formed very rapidly, and by their active movements
soon become detached from the body of the gametocyte, which, like
that of the Coccidia, is completely enucleated, except for its
karyosome, and perishes as residual protoplasm, together with the
contained melanin-granules. -Each microgamete is a slender
filament, slightly thickened in its middle portion, where is lodged
the chromatin which composes the greater part of its substance.
Like the microgametes of Adelea and Benedenia amongst Coccidia,
it has no true flagella, but progresses actively by serpentine move-
ments of the body in quest of a macrogamete.

In the macrogametocytes also the development is on the same
type as in Coccidia. The schizogony is completely suppressed,
and each macrogametocyte becomes a macrogamete after having
gone through a process of maturation by ejecting a portion of its
nucleus (Fig. 68, X5). It is then ripe for fertilisation.

The gametes conjugate in a manner essentially similar to that
described above in Coccidia. After the microgamete has pene-
trated the macrogamete, the two pronuclei fuse into a single
nucleus (Fig. 68, XI, XII). The zygote at first has the form of
a sphere, but soon after fertilisation it becomes elongated and
spindle-shaped, and grows into a small worm -like, or rather
gregarine-like body, which is actively motile, and has been

1 Schaudinn believes, with Grassi, that in some cases the Anopheles may be
naturally immune against the malarial parasite, and that such immunity, if acquired
by a whole race of the mosquito, would account for the disease having died out in
localities where it was formerly abundant, as in the eastern counties of England, for
example.

THE SPOROZOA

251

termed a vermicule by many writers (Fig. 68, XIII). Since it
corresponds exactly to the zygote of the Coccidia, but does not
form an oocyst immediately after fertilisation, Schaudinn has
proposed for it the name of ookinete, by which it is now generally
known. The movements of the ookinete are very similar to those
of a sporozoite, and consist of locomotion by gliding forwards,
combined with flexions and peristaltic contractions of the body
(Schaudinn [94a]).

The ookinete by its own activity bores through the epithelial
lining of the stomach of the mosquito, and comes to rest in the
tissues immediately below the epithelium. Here it becomes rounded
off again in shape, and a delicate cyst-envelope of disputed origin
becomes formed round it (Fig. 68, XIV). The zygote is actively
parasitic upon its new host, and commences to grow considerably
in size, bulging out the stomach-wall towards the body-cavity. The
ookinete has now become the ,

oocyst ("spore-cyst," Lankes-
ter), differing from that of the
Coccidia in the thinness of
its envelope, which permits it
to absorb nutriment, like a
gregarine. Over 500 oocysts
have been found by Grassi in
the stomach-wall of a single
Anopheles mosquito. As the
oocyst grows, its nucleus, at

first Single, divides tO form a ridl>. ?f.s> oesophagus _; sit, .stomach ; cy, cysts ; Alt,

number of daughter nuclei,
round each of which a small mass of protoplasm is centred (Fig. 68,
XV, XVI). The segments thus formed have received various names,
such as blastophores, zoidophores, or spore-mother-cells (Lankester),
but they are evidently comparable to the sporoblasts of Coccidia
and other Sporozoa, and may conveniently be designated as such.
The sporoblasts of the malarial parasites are irregular in form and
are not completely separated from one another, but remain in
connection by protoplasmic bridges. After formation of the
sporoblasts is complete a certain amount of residuary protoplasm
is left over, containing the melanin-granules originally present in
the gametocyte.

In each sporoblast the single nucleus divides repeatedly to
form a great number of small daughter nuclei, which travel to the
periphery ; the surface of the sporoblast then grows out into a
number of slender protoplasmic processes, each of which takes one
of the daughter nuclei with it (Fig. 68, XVII). In this way
are formed a vast number of minute spindle-shaped sporozoites
("blasts," "zoids," " exotospores "), each about 14 p. long by 1 //,

int.

Fio. 71.

Stomach of a mosquito, with cysts of Haemosj
lia. oes, oesophagus ; st, stomach
Malpighian tubules; int, intestine. (After Koss.)

252 THE SPOROZOA

in breadth. The sporozoites are at first implanted upon the
masses of residual protoplasm, representing the remnants of the
sporoblasts, but soon free themselves and perform active movements
within the cyst. The residual masses are usually enucleate, but
sometimes contain residuary nuclei, which may even multiply,
though doomed eventually to perish. Ultimately the residual
masses derived from different sporoblasts appear to fuse into a
smaller number of large granular masses, in which are found also
the melanin-granules of the sporont (Fig. 68, XVIII). The whole
number of sporozoites formed in this way in an oocyst is very
great, but varies within wide limits, from some hundreds to over
ten thousand. The mosquito observed by Grassi, of which mention
has been made above, might therefore have been capable of dis-
seminating about five millions of malarial germs.

During the whole period of the development of the sporo-
zoites, which lasts from ten to twelve days, the oocyst grows
continually in size. When the sporogony is complete the cyst
bursts, and the sporozoites are set free in thousands in the body-
cavity (haemocoele) of the mosquito. Here they are carried along
in the circulating blood -fluid, and in some way are attracted
towards the salivary glands, which they penetrate, filling the
secreting cells. When a mosquito thus infected bites a man, it
injects, in its usual fashion, a minute drop of saliva into the
puncture made by its proboscis, arid with the drop of saliva a
swarm of sporozoites pass down into the blood, each the starting-
point of a new infection and of many schizogonous generations.
Thus the life-cycle of the parasite has been brought round again
to the point which was selected for commencing the description.

From the above account it is seen that the life-cycle of the malarial
parasite is now thoroughly known in all its features. There is, however,
one point of importance still to be made out. In patients apparently
cured of malaria it may appear again without a fresh infection, and it is
not known what has been the condition of the parasite in the period
intervening between the first attack and the relapse. In cases of chronic
malarial cachexy, only crescents are to be found in the blood, and Grassi
has suggested that the gametocytes may have the power of non- sexual
reproduction in such cases, their offspring causing a reinfection of the
host. This point has recently been investigated by Schaudinn [94«] in
the case of the tertian parasite, and he finds that such cases of relapse
are brought about by a sort of parthenogenetic reproduction on the part
of the resistent, long-lived macrogametocytes. The nucleus of a macro-
gametocyte becomes slightly drawn out and shows at one extremity a
number of deeply-staining, coarse grains of chromatin ; it then divides
into two, so that the gametocyte contains two nuclei, one rich in chromatin
and staining deeply, the other pale and staining feebly. The body of
the gametocyte may become partially constricted into two parts, one with

THE SPOROZOA 253

denser protoplasm, with most of the pigment, and with the pale nucleus ;
the other with lighter protoplasm and less pigment, containing the dark
nucleus, which now proceeds to divide as in schizogony and gives rise to
a number of merozoites. The latter are the starting-point of fresh
schizogonous cycles of generation, bringing about a return of the fever.
The denser portion of the gametocyte with the pale nucleus is abandoned
as residual protoplasm and breaks up. Only the female gametocytes are
capable of reproducing themselves in this way. The microgametocytes,
with their greatly enlarged nucleus and reduced bulk of protoplasm (see
p. 248), are believed by Schaudinn to die off if they do not undergo their
natural course of development in the intermediate host.

Attention must also be drawn to another point which is not yet
fully explained. In mosquitos infected by these parasites, in addition to
the ordinary cysts containing sporozoites, there occur also other cysts of
about the same size, but very different in appearance, as they are filled
with masses of dark brown pigment, which is quite different in appearance
from the melanin-pigment of the parasites. Ross was the first to describe
these bodies in C'ulex infected by Haemoproteus danilewskyi in birds, but
they occur also in Anopheles infected with human malarial parasites.
They have received various designations: "yellowish -brown bodies,;;
Grassi ; " black spores," Ross ; " brown spores," Nuttall. Ross regarded
them as resistent cysts, destined to develop in some unknown way,
and Grassi at first thought they were intended to spread the infection
amongst successive generations of mosquitos. It is, however, sufficiently
well established that mosquitos neither come into the world infected with
these parasites, nor acquire them in any other way but from the blood of
their prey. Most authorities incline now to the later opinion of Grassi,
and regard the yellowish-brown bodies as degenerate cysts of the ordinary
kind, the pigment being produced by a protoplasmic mass consisting partly
of the residual substance, partly of abortive sporozoites left behind in the
cyst. This conclusion receives indirect support from the observations of
Schaudinn [5 la] upon the degenerated oocysts of Cyclospora (see p. 273).

In the above description of the life-cycle, the mosquito has been referred
to as the " intermediate host." Many authorities, however, such as Grassi,
Mesnil, Laveran, and others of great note, consider that the Invertebrate
host, the mosquito, should be regarded as the "principal" or "definitive "
host, and the Vertebrate, man, as intermediate, chiefly on the ground that
the sexual phases of the parasite are passed through in the former. In
considering these conceptions, it should be made clear at the outset in what
sense the term " principal host " is used. If it be employed in the sense
of the primary or primitive host, then it must certainly be applied to the
Vertebrate, for, while all the Haemosporidia have a Vertebrate host, there is
at present no evidence whatever, in the case of many of them, that an
Invertebrate host has been acquired as a means of dispersal (see below,
p. 263). The Haemosporidia as a whole must be considered as parasites
of Vertebrates in the first instance, which have in some cases adapted
themselves for certain phases of their life-history to a secondary Invertebrate
host. If, on the other hand, the term "principal host" be employed in a
physiological or functional sense, it is again the Vertebrate that must be

254 THE SPOROZOA

so distinguished. The essence of being a parasite is not to reproduce
sexually, but to flourish at the expense of other creatures, and the term
" host " denotes the being that suffers in proportion as the parasite profits.
Of the two hosts of the malarial parasite there can be no question that in
this sense also the Vertebrate is the principal one, since the mosquito appears
to suffer scarcely at all. It certainly would not be in the interests of the
parasite that the vitality of the mosquito should be lowered and its
appetite impaired.

Those who term the Vertebrate the intermediate host of the malarial
parasite, do so chiefly on the analogy of parasitic worms, Cestodes or
Trematodes, in which the sexual stages are passed in the definitive host,
the larval stages in an intermediate host. But the relation between
schizont and sporont can scarcely be considered analogous to that between
Cercaria and Distomum, for example. The comparison should be rather
with the summer and winter generations of Aphis or Daphnia, or with
Hydroid and Medusa.

The variations in the structure and life-history of other
Haemosporidia, as compared with the type here selected, are best
considered, as was done in Coccidia, first from the point of view of
the morphology of the individual stages, secondly from that of the
life-cycle considered as a whole.

(1) Morphology. — The trophozoites of Haemosporidia may be
distinguished, speaking generally, either as "haemamoebae" or as
"haemogregarines." Those parasitic upon cold-blooded Vertebrates
are not amoeboid like the malarial parasites, but have a fixed body-
form like minute gregarines (Figs. 75-77). This is true not only
of the " free " phases, but also of the endoglobular forms. They
occur generally as tiny vermicules, lodged in the blood-corpuscle or
free in the blood-plasma. When free they are often very active
in their movements, bending and twisting their bodies from side
to side, or gliding forwards in the manner already described for
Gregarines or Coccidian sporozoites (pp. 180 and 210), by the help
of a secreted thread of gelatinous substance (Hintze [68]). The
fixity of the body-contour seems to be due to the dense hyaline
ectoplasm, in which myocy te-fibrillae can often be made out. The
haemogregarines vary greatly in size, in different genera, relatively
to the dimensions of the blood -corpuscles they attack. Thus,
while Lankesterella scarcely attains to half the length of the frog's
blood-corpuscle which it inhabits (Fig. 75), the species of Haemo-
gregarina parasitic in various reptiles grow to such a length that
in later stages the trophozoite becomes folded on itself in a
characteristic manner, in order to be packed away within the
limited space at its disposal (Fig. 77). The genus Piroplasma, on
the other hand, is characterised by pear-shaped trophozoites of
extremely small size, several of which may be lodged in a single
blood-corpuscle (Fig. 80).

THE SPOROZOA

255

The reproductive phases of the majority of Haemosporidia are
very imperfectly known, and in most cases the statements that
have been made require revision, or at all events reinterpretation,
in the light of recent discoveries. As regards the non-sexual
cycle, it is interesting to note that in many forms the schizogony
takes the most primitive form of multiplication by simple binary
fission. This is the case in the species of the genus Piroplasma,
where the pear-shaped trophozoite divides within the blood-
corpuscle into two twin bodies, from which circumstance the type-
species of the genus has received the specific designation bigeminum.
Each of the daughter trophozoites may in its turn divide again.
A similar binary fission occurs also in the species Haemogregarina
Ugemina, recently discovered by Laveran and Mesnil [79] in two
species of blennies. In the majority of Haemosporidia, however,
the schizont divides up simultaneously into a number of merozoites,

Haemogregarina Hgemina, Laveran, from the blood of blennies. a, the form of the parasite
found free in the blood • plasma. 6, parasite within a blood -corpuscle, preparing for divi-
sion ; the nucleus has already divided, c, the parasite has divided into two rounded corpuscles,
which assume the form of the free parasite, as seen in il, c, and /. Ar, nucleus of the blood-
corpuscle ; n, nucleus of the parasite. The outline of the blood - corpuscle is indicated by a
thick black line. (After Laveran.) Magnified about 1800 diameters.

which may be disposed in various ways. Besides the " rosette "
or " daisy " pattern described above for Laverania, they may be
arranged in the form of a " barrel," with the residual protoplasm
at one extremity, as in the Eimerian phases of Coccidia, or they
may be implanted on each side of the residuum, or in other ways.
Sometimes the arrangement may vary in the same species, as in
Lankesterella (Drepanulium) ranarum, where the merozoites may be
formed on one side only of the schizont, or may have the radiate,
daisy-like arrangement. The schizogony is usually intracellular,
and takes place within a blood-corpuscle, or in the cells of certain
internal organs, more particularly the spleen, liver, and bone
marrow. The schizont often becomes surrounded by a membrane,
forming a so-called cytocyst (Fig. 73). Sometimes, however, the
sporulation may be free, i.e. extracellular, especially in the spleen-
pulp.

In many Haemosporidia of cold-blooded animals there appears
to be a well-marked dimorphism in the schizonts, as well as in the

256

THE SPOROZOA

merozoites produced by schizogony. Within the cytocyst the
schizont may break up into smaller micromerozoites or larger macro-
merozoites.1 This occurs in the form Karyolysus lacertarum (Fig. 73),
and also in the haemogregarines infesting various snakes studied
by Lutz [82] and named by him " Drepanidium serpentium." In
the latter the two kinds of merozoites develop into two forms
of schizonts termed by Lutz microhaemozoites and macrohae-
mozoites respectively. Dimorphism in the cytocysts has also been
described by Labbe in Lankesterella, but has not been confirmed
by recent observers. The most obvious interpretation of these
facts would seem to be that in these forms the schizonts show a

a

d.

Karyolysus lacertarum, Labbe, sporulation. a, macroschizout crammed with plastinoid
granules (pl.y) encysted in a blood -corpuscle, forming a cytocyst. 6, later stage of the same ;
the schizont has grown in size, its nuclei (71) are multiplying, and the degenerated remains of
the corpuscle and its nucleus (D) form the outer envelope of the cytocyst. c, cytocyst con-
taining macromerozoites (MZ) and two residual masses of protoplasm (r.p), one at each pole.
The macromerozoites, distinguished by their large size, contain a few small plastinoid granules.
d, cytocyst containing micromerozoites (niz) and a single residual mass (r.p). N, nucleus of the
blood-corpuscle ; «, nucleus of the parasite. (After Labbe.) x about 1000 diameters.

precocious sexual differentiation comparable to what is seen in
Adelea amongst Coccidia.

Observations upon the sexual cycles of Haemosporidia are as
yet few and somewhat far between, and it is necessary to be very
cautious in making generalisations. The parasites of birds and
man have been the chief objects of research, but not much is
known with regard to the Haemosporidia of the lower Vertebrata.
Eecently, however, Hintze [68] has brought forward interesting
observations upon Lankesterella ranarum. The microgametocytes
(Fig. 75, g) are distinguished by their slender form, and by the
absence of all but the finest granulations in their protoplasm, from
the plump, coarsely granular macrogametocytes (Fig. 75, j), the
ordinary schizonts being intermediate in character between the
two. In the microgametocytes the nucleus contains a number of
chromatin granules, each of which divides into two. The nucleus

1 Commonly, but probably wrongly, termed microsporozoites and macrosporozoites.

THE SPOROZOA 257

then becomes fragmented, and the chromatin-granules, each still
half the size of those originally present, scatter themselves in
the cell and become the nuclei of microgametes, which are not
separated off simultaneously, but one by one, in an irregular
manner (Fig. 75, h, i). In the macrogametocytes the entire nucleus
divides into two, and one half degenerates, the other half be-
coming the pronucleus of the macrogamete (Fig. 75, k, I). In
Haemoproteus ( = Proteosoma), however, the maturation of the
macrogamete takes place, according to Schaudinn [93], by ex-
trusion of the karyosome, as in Coccidium.

It is common for the male and female gametocytes to be
distinguishable from one another by well-marked characters. The
microgametocytes have finely -granulated, hyaline protoplasm,
while that of the macrogametocytes is more coarsely granulated,
differences which have a considerable effect upon their staining
properties in microscopic preparations. On the other hand, the
grains of melanin-pigment are generally larger and more numerous
in the microgametocytes. In Halteridium the form of the nucleus
differs in the two sexes of the gametocyte (Fig. 79), and there is
consequently also a difference in the arrangement of the melanin-
granules, which in the male elements are placed at the two poles
of the body, but in the female gametocytes are evenly scattered
in the protoplasm.

The microgametes in all known cases are without any true
flagella, like those of Benedenia and Adelea amongst Coccidia, but
while in the human parasites and in the allied genera from birds
they are long, slender, and flagelliform, in Lankesterella they are
described as minute oval bodies, capable of amoeboid movement.
The formation of the male gametes, the so-called " flagella," is a
very striking and characteristic phenomenon, easily observed in the
Haemosporidia of warm-blooded vertebrates, and described in
many forms since it was first seen by Laveran. Macallum [83]
gives the following graphic description of the process : —

" The adult organism is seen to draw itself together into a
sphere within the red corpuscle, and sometimes immediately, but
more often after a short delay, it begins to be greatly agitated,
the pigment dancing about, and the surface of the sphere taking
on an active undulating motion, which lasts but a short time, for
the organism suddenly bursts from the corpuscle, scattering the
remains of the latter, and in its place beside the nucleus of the
corpuscle, which now lies free in the plasma, it throws out four
or more flagella, which thrash about wildly, and sooner or later
become detached and wriggle away. The sphere is much reduced
in size by this throwing out of flagella, and the pigment is con-
centrated. . . . The remains of the sphere continue to be agitated,
and after the loss of the flagella, its pigment sets up a most active

17

258

THE SPOROZOA

dancing. Often it constricts itself into two or more parts, which
may reunite. . . . Disintegration and death are the inevitable
fate of these remains of the flagellated body, even if it escapes for

FIG. 74.

Formation of gametes, and fertilisation, in Halteriilmm(\>a.r. birds), after Macallum. a, female
gametocyte in a blood-corpuscle. 6, the same assuming the spherical form, c, the same in the
spherical condition and freed from the disintegrated blood -corpuscle, d, mature male game-
tocyte in a blood -corpuscle, e, the same assuming the spherical form. /, the same freed from
the corpuscle, throwing out " flagella" or male gametes, g, male gametes swarming round a
female, which one of them (fl) is actually penetrating, h, the zygote throwing out a proto-
plasmic process on one side (the right), i, the zygote transformed from an inactive sphere into
a motile " vermicule," moving forwards, with the melanin-pigment gathered at the posterior
extremity. N, nucleus of the blood-corpuscle ; m.p, melanin-pigment ; fl, male gametes.

THE SPOROZOA 259

any length of time one of the voracious leucocytes which wander
about."

The conjugation was first observed by Macallum in the genus
Halteridium from birds, and his discovery gave the first clue to
the nature of the "flagella," and showed that the "Polymitus"
form belonged to the normal cycle of the parasite, in contradiction
to the views then prevailing amongst most authorities upon the
Haemosporidia, who regarded this phase of the parasite as a
process of degeneration. The following is the account of the process
of conjugation, and the subsequent formation of the motile zygote,
given by Macallum, whose figures are also reproduced here
(Fig. 74) : — " The two forms [i.e. a granular macrogametocyte
and a hyaline microgametocyte] lay at some distance from one
another [on the field of the microscope]. . . . The granular form
happened to escape from the corpuscle first, and lay perfectly quiet
beside the free nucleus and the shadow of the corpuscle. Soon
the hyaline body, becoming greatly agitated, burst from the
corpuscle and threw out active flagella, which beat about for a
few minutes and finally tore themselves loose. . . . One of the
four flagella passed out of the field, but the remaining three pro-
ceeded directly towards the granular form, lying quietly across
the field, and surrounded it, wriggling about actively. One of the
flagella, concentrating its protoplasm at one end, dashed into the granular
sphere, which seemed to put out a process to meet it, and buried its head,
finally wriggling its whole body into the organism, which again became
perfectly round. The remaining flagella, seeking to repeat this
process, were evidently repulsed, and soon became inactive and
degenerated. Immediately on the entrance of the flagellum, the
pigment of the organism was violently agitated, without, however,
any disturbance of the outline of the organism. Soon all became
quiet again, and the period of quiescence lasted about fifteen
minutes, when a conical process began to appear at one margin
of the organism, which, increasing in size, drew into itself most
of the protoplasm, the pigment, to a certain extent, being gathered
in the remainder. Finally, most of the pigment was concentrated
into a small round appendage, which remained attached to what
now had become an elongated fusiform body [the ookinete or
vermicule], which soon swam away with a gliding motion."

The fertilisation has been studied also by Schaudinn in Haemo-
proteus and in the tertian parasite, and by Hintze in Lankesterella.
In the two former a cone of reception is formed by the macrogamete,
but in the latter a fine canal is formed, along which the male
pronucleus is guided from the point of entry up to the female pro-
nucleus. The zygote resulting from fertilisation is in all cases,
apparently, at first a freely-moving gregarine-like vermicule or
" ookinete," which seeks out actively, and penetrates, the cells or

FIG. 75.

Lankesterella ranarum (Lank.) (par. Rana esculenta), phases of the life-history, a-/, schizogony.
a, youngest stages of the parasite ; mz shows a free merozoite ; tr, tr, two young trophozoites
within a blood-corpuscle, with one and two chromatin bodies respectively. 6, a blood-corpuscle,
containing a full-grown trophozoite (schizont), with numerous chromatin bodies, preparing to
sporulate. c, the schizont is taking the form of an U. d, The schizont has become spherical,
but still shows the line of suture between the two loops of the U in the last stage. «, the
schizont is a perfect sphere. /, the schizont is segmented up into a number of merozoites (mz)
round a mass of residual protoplasm (r.p). g-i, formation of microgametes. g, a full-grown
microgametocyte with minute chromatin corpuscles in the nucleus, h, the chromatin cor-
puscles are dispersed through the body, i, a microgainete (£ g.) is separated off, and another
is forming at +. j-m, maturation of the macrogamete. j, full-grown macrogametocyte. t, the
nucleus of the macrogamete has undergone division into two. I, one of the nuclei (»') is degen-
erating, m, at the spot where the nucleus of the macrogamete underwent degeneration, a
microgamete ( <£) has attached itself, and from this spot a flue canal leads to the nucleus of the
macrogairete. n-p, sporogony. n, a zygote, still motile, with fragmented imcleus. o, an
encysted zygote, or oocyst. p, a sporozoite. g-i and n are free in the blood-plasma, j-m are
in blood-corpuscles in the same way as a-/, o is encysted in an epithelial cell of the intestine.
N, nucleus of the blood -corpuscle ; n, of the parasite. (After Hintze.) Magnified 2250 diameters.

260

THE SPOROZOA 261

tissues in which it comes to rest and becomes encysted as an oocyst.
In all cases that have been recently studied, the oocyst is formed
in the epithelium of the digestive tract, either of the same or of an
intermediate host.

With regard to the sporogony, two types can be recognised,
the differences between which depend upon whether the oocyst is
actively parasitic upon the tissues in which it encysts, as in the
malarial parasites, or whether it forms round itself a tough
protecting membrane within which it is more or less independent
of its host or of external conditions, as in Lankesterella (Fig. 75, 6).
The latter case is undoubtedly the more primitive, and does not
differ essentially from the state of things seen in the Coccidia. In
the oocyst of Lankesterella the number of sporoblasts is relatively
small, and each sporoblast appears to give rise to a single sporozoite
only. This condition is related, in this instance at least, with
absence of an intermediate host. Sporogony and schizogony here
go on in the same animal. On the other hand, in the malarial
parasites of birds and man, perhaps of all warm-blooded animals,
sporogony takes place, as in Laverania, in an intermediate host, upon
which the oocyst is actively parasitic. The enveloping membrane
in these forms is very thin — according to Grassi it is formed by
the host and not by the parasite — and the zygote grows greatly
in size, forms a number of sporoblasts, and each sporoblast gives
rise to very numerous sporozoites, as described above for Laverania.
This great increase of reproductive power must be regarded as a
secondary adaptation of a kind common in all forms of parasitic
organisms, whereby the chances of disseminating the parasite
amongst fresh hosts are much heightened by the vast number of
germs produced from each- individual.

In no case, however, are sporocysts secreted within the oocyst.
The sporozoites whether few or numerous, are naked gymnospores,
similar to those of the genus Eimeria amongst Coccidia.

The Haemosporidia have been the object of extended studies on the
part of Labbe, many of whose statements, however, still require con-
firmation, especially with regard to the forms inhabiting cold-blooded
vertebrates, i.e. the genera Lankesterella, Karyolysus, and Haemoyreyarina.
It is asserted by him, with regard to the first two genera, that a trophozoite,
after growing to a certain size within a blood-corpuscle, becomes free in
the blood-serum, and that an isogamic conjugation takes place between
two perfectly similar free individuals ; and that then the zygote so
formed penetrates a second blood - corpuscle, or it may be a cell of the
spleen, liver, kidney, or bone-marrow, and forms a resistent cyst within
which it breaks up into sporozoites. A certain amount of scepticism has
grown up with regard to these statements, which are not in any way
confirmed by the recent observations of Hintze upon Lankesterella, and
receive no support from the analogy of what is known in other forms.

262 THE SPOROZOA

(2) Life-history, — It is probable that an alternation of genera-
tions, of schizogony and sporogony, occurs in all Haemosporidia, and
that there are no forms in which the schizogony is non-existent or
suppressed, as in Benedenia amongst Coccidia ; though there are
many in which the sporogony has not yet been described. The
most salient feature in which the life -cycles of different forms
differ from one another is the mode of infection ; that is to say,
with regard to the presence or absence of an intermediate host, in
which the sporogony takes place, and which serves to disseminate
the parasite. The brilliant investigations of Ross upon the Haemo-
sporidia of birds first demonstrated the agency of blood-sucking
gnats of the genus Culex in spreading the infection amongst avian
hosts, and the organised researches of Grassi and his Italian fellow-
workers have proved incontestably the part played by other mosquitos
of the genus Anopheles in carrying involuntarily the malarial germs
from one human being to another. In a similar way it has been
proved experimentally that the parasite of the Texas cattle-fever,
Piroplasma bigeminum, is transmitted from one ox to another by
ticks (Ehipicephalus annulatus = Boophilus bovis); but in this case the
part played by the intermediate (invertebrate) host is much more
complicated than in the infection of birds or man with malaria
by gnats, since the parasite passes through two generations of ticks.

The ticks which nourish themselves upon cattle and other mammals
become sexually mature at their last moult. They then pair, and the
fertilised females, after gorging themselves with blood, drop off on to the
ground. Each female then lays about 2000 eggs, and within the shell
of each egg a large quantity of blood is deposited, to serve as vitellus for
the developing embryo. When oviposition is completed, the female
shrivels up, and becomes a dried, empty, lifeless skin. From the egg
is hatched a larva, which has only three pairs of legs, and contains in
its abdomen a certain quantity of blood, the still unabsorbed remains
of its share of its mother's last meal. The newly-hatched larva crawls
on to a blade of grass or other convenient coign of vantage, from which
it either passes on to the skin of a fresh host, or drops off dead from
starvation, if no favourable opportunity occurs for changing its situation
before its supply of blood is exhausted.

A remarkable fact, with reference to the transmission of Texas-fever,
was first demonstrated experimentally by Smith and Kilborne, and subse-
quently confirmed by Koch [70] and other observers, namely, that if the
mother-tick drew its supply of blood from an ox infected with Piroplasma,
her progeny are born into the world infected with the parasite, and become
the means of disseminating the disease amongst healthy cattle. Thus is
explained the long incubation -period of the disease, the time required
for it to spread from diseased to healthy cattle being about forty -five to
sixty days ; of this thirty days are taken up by the development of the
egg of the tick, the remainder probably by the development of the
parasite within the ox (Smith [97]).

THE SPOROZOA 263

From the facts it would appear at first sight as if the infection of
the young ticks was a case of true hereditary infection, parallel to the
" pdbrine " disease of the silkworm. But it is quite possible that the
tick-embryo acquires the infection secondarily from the blood it absorbs
in the egg, and it does not follow that the parasitic germs pass through
the ovum itself as in Glugea. Until something is known of the stages
of the parasite within the tick, it is not possible to decide whether this
is a case of true hereditary infection or not.

The number of instances in which intermediate hosts have been
demonstrated for Haemosporidia has been increased so steadily
by recent researches that many authorities are inclined to the
belief, to which expression has recently been given by Borner, that
for all species of Haemosporidia there is some blood-sucking animal
which is the agent in the dissemination of the parasites, and that
where no intermediate host is known, it merely remains to be
discovered.

There are, however, many grounds against believing that an
intermediate host occurs in all cases. First, on general grounds,
if the modern conception of the Haemosporidia as forms closely
allied to Coccidia, adapted to parasitism upon blood -cells, be
correct, it is reasonable to suppose that the ancestors, at least, of
the group under consideration were at first without any special
means of dissemination other than the resistent spores and cysts
found in Coccidia and Sporozoa generally ; and if this be admitted,
it becomes further highly probable that representatives of these
primitive forms will be found to exist at the present day.
Secondly, empirical grounds are not wanting to support these
conclusions, although decisive experimental proof is lacking as
yet. In a great many instances amongst the Haemosporidia of
the lower Vertebrata, sporogony as well as schizogony occurs
in the Vertebrate host. In the case of the Lankesterella of the
frog, Hintze has shown that the motile zygote leaves the blood to
encyst in an epithelial cell of the gut, and that the resistent cyst
so formed passes out with the faeces. We find here, therefore,
just those conditions for disseminating the parasites which are
most typical of Sporozoa generally. It is highly probable that the
infection of the frog by Lankesterella is a casual one, brought about
by the frog swallowing cysts of the parasite accidentally, and this
conclusion is supported by the fact that, according to Hintze's
observations, frogs living in pools and confined spaces are especially
liable to the infection, while those from rivers and large areas of
water are almost entirely free from it.1

There is therefore a very strong case in favour of the view

1 Compare the very similar case of Liihobius from different localities as regards
infection with Coccidium, above, p. 221.

264 THE SPOROZOA

expressed by Schaudinn, namely, that many Haemosporidia,
especially those of cold-blooded Vertebrata, are not disseminated
by an intermediate host, but that the infection is a casual one,
as in any other kind of Sporozoa. It is evident that the acqui-
sition of an intermediate host is an adaptation which is vastly
beneficial from the point of view of the parasite, as is shown by
the rapidity with which the diseases caused by them spread in
countries where the two necessary conditions occur — the presence,
that is to say, both of the parasite and of its blood-sucking inter-
mediate host. The latter in all cases hitherto investigated has
turned out to be an Arthropod, within which the sporogony of
the parasite takes place, and upon which the oocysts are actively
parasitic. A general survey of the life -cycles of Haemosporidia
and Coccidia would lead one, however, to believe that primitively
the sporulating stages would not have been parasitic upon the
intermediate host, but that the latter would have acted merely as
a carrier and not as a host, in the strict sense of the word. A
life-cycle of this kind remains as yet hypothetical, but may be
postulated as a stage in the evolution of the adaptive relation
between parasite and blood-sucker, even if non-existent at the
present day.

(c) Classification. — The nomenclature and taxonomy of the Haemo-
sporidia is in a very confused state. It is not uncommon to find the same
form appearing in the literature under three or more different names,
or to see the same name applied to designate totally distinct objects. Of
recent years, however, much has been done to introduce order into this
chaos, and students of the group are slowly but surely coming to an
agreement as to the correct names of the different forms of Haemosporidia,
in accordance with settled zoological usage. There is still, however, con-
siderable diversity of opinion as to the manner in which the parasites
should be grouped together.

Labbe [4] classifies the Haemosporidia, as here understood, under two
orders, the Haemosporidia sensu stricto, and the Gymnosporidia ( = Acysto-
sporidia of Wasielewski). The first of these divisions comprises the species
parasitic for the most part upon cold-blooded animals, in which schizo-
gony and sporogony occur in the same host. The Gymnosporidia, on the
other hand, are the forms parasitic upon warm-blooded hosts, and owe
their name to the fact that no resistent cysts are formed by them in the
Vertebrate host, since the sporogony takes place, so far as has been
observed, in an intermediate Invertebrate host. Eecent authorities have
for the most part abandoned this classification, but in so far as it
separates the more primitive forms, without special intermediate hosts,
from those in which an alternation of habitat has been evolved, it is
probably a useful and, to a large extent, a natural mode of grouping
these parasites. Labbe's two orders have therefore been revived by
Neveu-Lemaire [88] as two sub-orders of the order Haemosporidia, and
they are retained here in this sense, but with the terminations altered, in

THE SPOROZOA 265

order to avoid confusion between the name of the order and that of the
first of the two sub-orders.

The majority of writers upon the Haemosporidia are content simply
to enumerate the various genera comprised in this order, without group-
ing them into families. Recently, however, Neveu-Lemaire has recognised
four families, without defining them, to include a certain number, but
not all, of the known genera of Haemosporidia. These are — (1) the
family Haemogregarinidae, equivalent in extent to the whole sub- order
Haemosporidia sensu stricto, and comprising the genera Lankesterella
( = Drepanidium), Karyolysus, and Haemogregarina ; (2) family Haem-
amoebidae (Wasielewski), comprising the genera Plasmodium, Laverania,
and Haemamoeba ( = Haemoproteus s. Proteosoma) ; (3) family Halterididae
for Halteridium and Polychromophilus ; (4) family Achromaticidae for Achro-
maticus and Dactylosoma (synonym of Drepanidium}. Amongst the genera
left out in the cold is Piroplasma ( = Apiosomd), a genus which is
sufficiently well characterised to be the type of another family ; while on
the other hand the position and importance of the genera Polychromo-
philus and Achromaticus must remain for the present doubtful. The
arrangement of the genera in families seems, therefore, rather premature
in the present state of knowledge.

With regard to number of generic types to be recognised amongst
the Haemosporidia, the greatest diversity of opinion prevails. Laveran
[75, 77], to whose authority, as the original discoverer of the malarial
parasites, the greatest weight attaches, recognises but three genera :

(1) Haemamoeba [including Plasmodium, Laverania, Haemoproteus, etc.] ;

(2) Piroplasma; and (3) Haemogregarina [including Drepanidium and
Karyolysus]. This classification has at least the merit of simplicity,
but in lumping the genera together to such an extent, Laveran is not
followed by other writers, and his three genera are to be regarded rather
as representing groups of the value of families in a natural system.

In the following systematic review, the genera best characterised and
commonly recognised are given first, and then a certain number of
doubtful forms are briefly mentioned.

ORDER Haemosporidia, Danilewsky.
SUB-ORDER I. HAEMOSPOREA.

Trophozoite typically a vermiform haemogregarine, endoglobular in
early stages, free when full grown. Apparently no alternation of hosts ;
schizogony and sporogony in the same host, which is always a cold-blooded
vertebrate, fish, amphibian, or reptile.

Genus 1. Lankesterella, Labbe, 1899 (for Drepanidium, Lankester,
1882), preoccupied. The haemogregarine is not more than three-fourths
the length of the blood-corpuscle it inhabits. Type-species L. ranarum,1
Lankester (Fig. 75), parasitic on Rana esculenta ; L. monilis (Labbe), from

1 According to Hintze [68], this form was first described by Chaussat in 1850
under the name of Anguillula minima, so that its correct designation would be
Lankesterella minima (Chaussat).

266

THE SPOROZOA

the same host, is apparently a distinct species. L. avium (Labbe"), from
birds, is believed by Grassi to be the ookinete stage of Halteridium
danilewskyi. Genus 2. Karyolysus, Labbe", 1894. The haemogregarine

a

FIG. 76.

Karyolysus lacertarum(Da,ml.), in the blood-corpuscles of Lctcerta muralis, showing the effects
of the parasite upon the nucleus of the corpuscle. In c and d the nucleus is broken up. N,
nucleus of the corpuscle ; n, nucleus of the parasite, seen as a number of masses of chromatin,
not enclosed by a distinct membrane. (After Marceau.)

does not exceed the blood-corpuscle in length. One species, K. lacertarum
(Daiiil.) (Figs. 73, 76), from lizards (Lacerta spp.). To this genus, probably,
should be ascribed the parasite of Testvdo ibera described by Popovici [91],

f.

FIG.

Haetnogregarina stepanovi, Danilewsky (par. Emys and Cistudo), phases of the schizogony.
a, blood-corpuscle with young trophozoite. ft, older trophozoite. c, full-grown trophozoite,
ready to leave the corpuscle, d and e, trophozoites free in the blood-plasma, showing changes
of form, f-i, trophozoites still within the blood-corpuscle to show the structure of the nucleus,
the coarse chromatoid granules in the protoplasm, and the manner in which the parasite grows
into the U-shaped haemogregarine without increase of body -mass, j, commencement of sporu-
lation ; the nucleus has divided into eight nuclei, and the body of the parasite is beginning
to divide up into as many merozoites within a blood -corpuscle. N, nucleus of the blood-
corpuscle ; n, nucleus of the parasite, (a-e and j after Laveran ; f-i after Borner.) x 1000-
1200 diameters.

and perhaps also the " Drepanidium serpentium" described by Lutz [82]
from a number of species of snakes. Genus 3. Haemogregarina, Danilewsky,
1885 (syn. Danilewskya, Labbe, 1894). The body of the parasite exceeds

THE SPOROZOA 267

the blood-corpuscle in length when adult, and is bent on itself within
it in a characteristic manner, like the letter U. A large number of
species from reptiles (Chelonia, Lacertilia, Ophidia, Crocodilia), of which
the commonest are H. lacazei (Labbe'), from Lacerta agilis, and H. stepanovi,
Danil. (Fig. 77), from Emys lutaria and Cistudo europaea. H. magna
(Gr. et Fel.), occurring in the frog, Sana esculenta, is perhaps the macro-
gamete of Lankesterella ranarum or L. monilis. Three species have recently
been described from fishes : H. delagei, Lav. et Mesn., from Raia punctata
and R. mosaica, H. simondi, Lav. et Mesn., from the sole, and H. bigemina,
Lav. et Mesn. (Fig. 72), from two species of blennies. A doubtful species
has even been described by Eisen under the name H. nasuta, from the
blood of an Annelid (Edipidrilus frigidus).

SUB-ORDER II. ACYSTOSPOREA.

The trophozoite is an amoeboid haeinamoeba, or is of simple body-
form, and is typically endoglobular throughout the schizogonous cycle.
An alternation of hosts is known in many instances to occur ; the
schizogony takes place in the vertebrate host, usually a warm-blooded
animal (bird or mammal) ; the sporogony takes its course in an
invertebrate host, which is an arthropod in all cases hitherto observed.

Genus 4. Plasmodium, Marchiafava et Celli, 1885 (syn. Haemamoeba
auct.). The haemamoebae contain granules of melanin-pigment. The
merozoites are oval in form, arranged in a single group round a central
residual body. Gametocytes spherical. Two species generally recognised,
both parasitic upon man ; see above, p. 243. To this genus also Liihe
refers the form discovered by Kossel in apes, and named by Laveran
Haemamoeba kochi.1 Genus 5. Laverania, Gr. et Fel., 1890 (syn.
Haemomenas, Ross, 1899). Trophozoites and merozoites as in the last.
Gametocytes crescent -shaped. One species, L. malariae, Gr. et Fel.
(syn. Haemamoeba s. Haemomenas s. Plasmodium praecox, etc.), parasitic
in human blood ; see above, p. 243 (Fig. 68). Genus 6. Haemoproteus^
Kruse, 1890 (syn. Proteosoma, Labbe, 1893). Trophozoites and merozoites

1 Schaudinn, in his monograph on the tertian parasite [94a], unites forms here
placed under the three genera, Plasmodium, Laverania, and Haemoproteus, in one
genus, to which he gives the first of these three names ; since he does not consider
the differences in the form of the gametocytes to be an adequate generic distinction.
The genus Plasmodium in his revision contains the following species : —

(1) P. malariae (Lav.), quartan parasite of man.

(2) P. vivax (Gr. et Fel.), tertian parasite of man.

(3) P. immaculatum (Gr. et Fel.), parasite of human pernicious malaria.

(4) P. praecox (Gr. et Fel.), the "Proteosoma" parasite of birds.

(5) P. kochi (Lav.), from the blood of apes.

The genus Halteridium Schaudinn considers to be distinct, but he declares that it
should be named Haemoproteus, so that the halter-shaped parasite of birds stands as
Haemoproteus danilewskyi (Gr. et Fel.) !

The confusion in the scientific names of these parasites is now so great as to lead
to the remarkable result that the popular names commonly given to them furnish
more distinctive and intelligible appellations than the ever - changing "correct"
taxonomic nomenclature."

268

THE SPOROZOA

as in the preceding. Gametocytes bean-shaped.1 One| species, H. dani-
lewskyi, Kruse (syn. Proteosoma grassii, Labbe), parasitic on a large number

/ N

FIG. 78.

Haemoproteus danilewskyi, Kruse (par. birds), a, young trophozoite in a blood-corpuscle.
b and c, older trophozoite. d and e, sporulation. d, precocious sporulation, with few mero-
zoites. e, sporulation of a full-grown schizont, with numerous merozoites. /, gametocyte.
N, nucleus of blood-corpuscle ; n, nucleus of parasite ; p, pigment ; mz, merozoites ; r.p, residual
protoplasm. (After Labbe.) x about 1200. [a, 6, c, and /from the chaffinch ; d and e from
the lark.]

PIG. 79.

HaUeridium danilewskyi (Gr. et. Fel.) (par. birds), various stages, a, young tropho-
zoite in a blood-corpuscle. 6, older trophozoite. c, macrogametocyte with spherical nucleus
and evenly-scattered pigment-granules, d, microgametocyte, with elongated irregular nucleus
and pigment-granules at the two extremities of the body, e, double infection, micro- and
macro-gametocyte in the same corpuscle. /, macrogametocyte throwing out pseudopodia.
g-l, schizogony. g, early stage of schizogony ; the nucleus of the schizont has divided into
two nuclei which travel to the two extremities of the body, h, the same stage more advanced.
i, each of the two nuclei of the preceding stage has divided into four, j, the nuclei at the two
poles have become very numerous, k, separation of merozoites (mz) and residual protoplasm
(r.p) containing the pigment -granules ; at one pole the arrangement of the merozoites is
roughly fan-like, at the other, mulberry-like. I, commencing liberation of the merozoites.
In the final stages of schizogony (i-l) the blood - corpuscle is acted upon and more or less
broken up by the parasite. N, nucleus of blood-corpuscle ; n, nucleus of parasite ; p.g, pig-
ment granules, (a-/ after Laveran ; g-l after Labbe.) x about 1200. [a-f from the pigeon ;
g-j and I from the lark ; k from the chaffinch.]

of common birds (Fig. 78). The intermediate host is a gnat of the genus
Culex. Genus 7. HaUeridium, Labbe, 1894. Trophozoites as in the

1 According to Neveu-Lemaire, the name Haemamoeba, Gr. et Fel., 1890, lias
the priority over Haemoproteus for this genus ; but the case does not seem very
clear, and since the name Haemamoeba has many applications, and is often employed
in a general as well as in a taxonomic sense, confusion is avoided by keeping to
Kruse's name.

THE SPOROZOA

269

preceding ; merozoites disposed in two groups, connected by the residual
body. Gametocytes bean -shaped. One species, H. danilewskyi (Gr. et
Fel.), parasitic upon various common birds (Fig. 79). Intermediate host
not known. [The two forms of endoglobular parasites found in the blood
of birds, Haemoproteus and Halteridium, are easily distinguished in all
but the very youngest stages. Haemoproteus has an irregular, more or
less compact form, occupies the centre of the corpuscle, and pushes the
nucleus to one side, often compressing or deforming it (Fig. 78) ;
sporulation takes place in the peripheral circulation. Halteridium, on
the other hand, grows in a characteristic manner so as to resemble a
halter in form, surrounding the nucleus, which is scarcely or not at all
displaced (Fig. 79) ; it sporulates only in the internal organs, especially
in the spleen and the bone-marrow.] Genus 8. Piroplasma, Patton,
18951 (synn.Pi/rosoma, Smith et Kil borne, 1893; Apiosoma, Wandol-
leck, 1895 ; Babesia, Starcovici, 1893). Trophozoites amoeboid, ovoid,

k.

FIG. 80.

Development and schizogony of Piroplasma bigeminum in the blood-corpuscle of the ox. a,
youngest form. 6, slightly older, c and d, division of the nucleus, e and /, division of the
body of the parasite, g, h, i, j, various forms of the twin parasite, k and I, doubly-infected
corpuscles. (After Laveran and Nicolle.)

or pear-shaped ; schizogony by simple fission. Sexual cycle and sporo-
gony unknown. Type-species P. bigeminum (Sm. et K), parasite of Texas
cattle-fever (Fig. 80) ; the disease is known to be transmitted by the
bites of ticks (see above), but the phases of the parasite in the intermediate
host have not been studied. Hunt [69] has found crescents in the blood
of cattle, and has observed their change into a spheroidal shape, but
while comparing these bodies to the crescents of the malarial parasites,
he at the same time regards them as a form of sporulating body producing

1 The nomenclature of the parasite of Texas-fever and its congeners is in a very
confused state. The generic name Pyrosoma given to it by Smith and Kilborne in
1893, being preoccupied for the well-known Ascidiau genus, was altered to Piro-
plasma by Patton in 1895 (not 1885, as wrongly stated by Labbe [4]), and in the
same year Wandolleck gave it the name Apiosoma, Avhich, however, had previously been
given by Blanchard in 1885 to a genus of Ciliata (for Apiosoma jnscicola, ectoparasitic
upon the skin of fishes). From these data, Piroplasma would appear to be the correct
name ; but in 1893 Starcovici gave the name Babesia bovis to the blood-parasite of
cattle described by Babes (1888) under the name Haematococcus bovis, which according
to Laveran is identical generically and specifically with the Texas-fever parasite. If
that is the case, the correct name of the genus would be Babesia, and the species
parasitic on oxen should be called Babesia bovis (Babes).

270 THE SPOROZOA

spores endogenously, having mistaken the coarse granules in them for
minute spores. Doflein [2a], however, distinguishes minute individuals,
reproducing by schizogony, from large pear-shaped forms, which he
regards as gametocytes. The latter have been observed by Lignieres [8 la]
to round themselves off, and even (as this author's observations are inter-
preted by Doflein) to throw out " flagella," i.e. microgametes. The rela-
tions of the various phases hitherto observed, and their true role in the
life-cycle, is at present, as Doflein observes, purely conjectural. Other
species are P. canis, Piana et Galli-Valerio ; P. ovis (Starcovici) ; and P.
equi, Laveran. P. canis has also been proved to be disseminated by dog-
ticks ; in South Africa by Haemaphysalis leachi ; in Europe, apparently
by Dermacentor reticulatus. See Nocard and Motas [89].

The following genera are of uncertain value, and can only be accepted
provisionally : —

Polychromophilus, Dionisi, 1900, for two species, P. murinus, from
the blood of Vespertilio murinus, and P. melanipherus, from another bat,
Miniopterus schreibersii. Intermediate host unknown. Trophozoites and
merozoites as in Plasmodium.

Achromaticus, Dionisi, 1900, for A. vesperuginis, from the bats of the
genus Vesperugo. Distinguished from the preceding only by the absence
of melanin-pigment in the haemamoeba. Intermediate host unknown.
Neveu-Lemaire refers to this genus the species Haemamoeba subimmaculata,
Gr. et Fel., from certain birds, perhaps a variety of Haemoproteus dani-
lewskyi, Kruse.

Cytamoeba, Labbe, 1894, for G. bacterifera, Labbe, from the blood of
Rana esculenta, remarkable for containing commensal bacteria. Perhaps
a pathological variation or deformation of Lankesterella ranarum.

Dactylosoma, Labbe", 1894, for D. ranarum ( = D. splendens, Labbe =
Laverania ranarum, Grassi), from the blood of Rana esculenta, is, according
to Hintze, a variety of Lankesterella ranarum.

Karyophagus, Steinhaus, 1889 (syn. Acystis, Labbe', 1894), for three
species parasitic upon the epithelium of the intestine in the salamander
(K. salamandrae, Steinhaus), the newt (K. tritonis, Steinh.), and the frog
(K. ranarum, Labbe). They are Eimerian phases of Coccidia (see p. 230).

Haemapium, Eisen, 1897, for H. riedyi, an endoglobular haemamoeba
from the red blood-corpuscles of Batraclwseps attenuatus (Urodela).

Finally, there remains for mention a species of which the exact posi-
tion is not yet clearly denned, and which has been described under the
generic designation Haemamoeba, in the sense of Laveran (see above,
p. 265), namely, H. metchnikovi, Simond, from Trionyx indicus, observed
at Agra. It occurs as a minute pigmented endoglobular amoebula
resembling the malarial parasites of birds and mammals. Its presence in
a cold-blooded animal is therefore remarkable and quite exceptional.
The amoebulae grow into reniform bodies of two kinds, one with fine, the
other with coarse pigment-granules. In addition there is found in the
blood of the same hosts a non-pigmented haemogregarine which Simond
believes to be also a phase of this parasite. Further investigations of
this interesting form are required, and Laveran admits it only with
some reserve to rank in his genus Haemamoeba,

THE SPOROZOA 271

Comparison of the Life-Cycles of the Telosporidia.

It is evident that the Haemosporidia resemble the Coccidia
very closely in all essential points. Their life -cycle can be
described in identical terms, and the points of difference are
mainly adaptive. They might, in fact, be considered simply as
Coccidia adapted to parasitism upon a special form of cell, the
blood-corpuscle, as has been done by Mesnil (see p. 229, footnote).
This point of view is not, however, strictly accurate, as the
Haemosporidia exhibit certain features, not obviously correlated
with their mode of life, which are not seen in Coccidia. Such
are (1) the frequent occurrence of amoeboid phases in the growth
of the trophozoites ; (2) the free, extra -cellular gregarine-like
forms characteristic of one sub-order ; (3) the occurrence of schizo-
gony by simple binary fission ; and (4) the motile " vermicule "
phase of the zygote. Some of the above characters, notably
(1) and (3), are clearly of a primitive nature, and could easily be
explained as an inheritance from an ancestor common to them
and to the Coccidia.

The two orders Haemosporidia and Coccidia may therefore be
regarded as two very closely allied groups of the Telosporidia,
which have diverged from a common origin in two directions, in
accordance with the difference in their habitat. Doflein has
recently given expression to this view by placing the Coccidia
and the Haemosporidia as two sub-orders of a single order, the
Coccidiomorpha.

On the other hand, the exact homologies between the different
stages of the life -cycles of the Gregarinida and Coccidiomorpha
respectively are not so obvious, and require brief discussion. In
both groups the life-cycle may be complicated by schizogony, but
for purposes of detailed comparison it is necessary to eliminate all
secondary or adaptive phases of development, and to select types
in which the life-history runs the simplest course. In other words,
the comparison must start from the consideration of a mono-
genetic type of development by sporogony, such as is found in
the vast majority of Gregarines, and in Benedenia amongst Coccidia.

In a typical Gregarine such as Monocystis, or, better still,
Stylorhynchus, the life-cycle may be formulated as follows : —

In a monogenetic Coccidian, the life -cycle may be expressed
thus :

THE SPOROZOA

Comparing these two formulae,1 it is seen that the main
differences between the two types are seen in two points. First, the
female gametocyte in Coccidia gives rise only to a single female
gamete, instead of to a number of them, and consequently there
is only a single zygote, and a certain number of male gametes are
wasted ; secondly, the zygote of the Gregarine becomes a sporo-
blast, and ultimately a spore, but the zygote of the Coccidian
becomes the oocyst, and gives rise to a number of sporoblasts, each
of which becomes a spore.

The facts stated above have led some authors to abandon the
obvious comparison of spore to spore and cyst to cyst in Grega-
rinida and Coccidiidea respectively. Taking the zygote as the
fixed point, so to speak, in both types of development, it has been
urged that the product of zygosis should be strictly homologised
and that therefore the Coccidian oocyst should be compared with
the Gregarine sporocyst. From this basis of comparison the
Coccidian sporocyst is something not represented in Gregarines,
and similarly the Gregarine cyst is without parallel amongst
Coccidia. This interpretation of the homologies seems to raise
more difficulties than it solves, and we shall attempt to show that
the facts can be interpreted differently, and in a manner at once
simpler and more natural.

There is one point in which the two life-cycles differ, which is
not shown by the formulae given above, but which is of crucial
importance. In Gregarines the two sporonts become enveloped in
a common cyst before they give rise to gametes, and the entire
process of zygosis goes on within the cyst. In Coccidiomorpha
the zygosis takes place between free gametes, which become
encysted after the process is complete. The rare instances in which
an oocyst is secreted by the female gamete before fertilisation, as
in Coccidium proprium, etc. (p. 227), is not really an exception to
this rule, since here also the male gametes are free, and a micro-
pyle is left for their entry into the oocyst.

The relation of the encystment to the zygosis is probably the
clue to the solution of the problem, and affords a means of tracing
a simple phylogenetic origin for the two divergent types of life-
history. As an ancestral condition, common to all Telosporidia,
we may assume a type in which the gametocytes each formed a
number of gametes, as in Gregarines, these gametes, however, being,
like those of the Coccidia, free, that is to say, not enveloped in
any cyst. The trophozoites of this ancestral form were probably

1 The formulae of the life-cycles are simplified, but not modified for purposes of
comparison, in those cases in which the sporoblasts are transformed into gymnospores
or so-called sporozoites, as in Aggregata amongst Gregarinida and Eimeria (Legerella)
amongst Coccidiidea. In such cases, instead of " n Sporoblasts->-M Spores x mn
Sporozoites," we must write " n Sporoblasts->-?i Gymnospores " ; or, for Haemosporidia
or Aggregata, "n Sporoblasts x mn Gymnospores (Sporozoites)."

THE SPOROZOA 273

entirely intracellular, and the gametes formed by them were prob-
ably differentiated into active male gametes and passive female
gametes. Nevertheless, the male gametes must often have failed
to find the female gametes, which would then have to develop
parthenogenetically, or to perish unfertilised. From this hypo-
thetical ancestral stage the state of things existing in both
Gregarines and Coccidiomorpha may be derived by simple processes
of adaptive improvement and specialisation.

In the Gregarines, with the acquisition of an intercellular
trophic stage, it became possible for the gametocytes to associate
and become encysted together, so that the gametes are formed in
a confined space, and there is no possibility of the male gamete
failing to find the female. In correlation with this condition the
differentiation of the gametes becomes less important, and, as L6ger
has pointed out, conjugation takes place prematurely between
immature gametes, a condition which, carried further, has probably
led to the complete isogamy of such forms as Monocystis.

In Coccidia the trophozoites remain intracellular, and hence
the gametocytes are usually kept apart, though occasionally
premature association takes place (Adelea, etc.). Correlated with
this state of things, a very great specialisation of the gametes is
brought about. In the female gametocyte the process of multipli-
cation to form gametes is in abeyance, and each female gametocyte
becomes a female gamete after elimination of nuclear substance.
The male gametes, however, are produced usually in large numbers
from the gametocyte (only when there is precocious association
of gametocytes is the number of male gametes reduced), and the
gametes themselves are of a highly specialised type. Thus the
probability of a male gamete finding a female is very great, even
if not a certainty, as in the Gregarines. Immediately after fertilis-
ation the zygote divides to form the sporob lasts, which may be
compared to those of Gregarines by supposing that the process of
multiplication by which the gametocyte of the Coccidia gave rise
primitively to a number of female gametes has not been com-
pletely suppressed, but merely deferred until after the process of
zygosis.

From this point of view the female gamete of the Coccidia must
be compared not to a single female gamete of a Gregarine, but to
the whole number of those produced from a female gametocyte in
the latter, the actual process of cell-division being temporarily
arrested. This interpretation receives the strongest support from
some remarkable observations recently made by Schaudinn [5 la]
upon the life-cycle of the Coccidian, Cydospom caryolytica, parasitic
on the mole. In this form, as described above (p. 225), the
nucleus of the macrogamete normally throws off two " reduction-
nuclei" which degenerate, and the reduced pronucleus then

18

274 THE SPOROZOA

copulates with one of the numerous microgametes which penetrate
the female gamete (see p. 227). But in a large number of cases
Schaudinn observed that the reduced pronucleus underwent de-
generation, while the reduction-nuclei, on the contrary, flourished
and continued to divide, populating the macrogamete with a large
number of nuclei. In such cases, when the usual swarm of micro-
gametes entered the macrogamete, each microgamete copulated
with one of the numerous nuclei of the macrogamete, the result
being a process of multiple fertilisation of the macrogamete, round
which an oocyst is secreted in the usual way. There can be no
doubt that, as Schaudinn suggests, this multiple fertilisation is,
from the phylogenetic point of view, a reminiscence of an ancestral
condition in which the female gametocyte produced numerous
female gametes, each capable of being fertilised by a microgamete.
The effects of this multiple fertilisation upon the Cydospora are,
however, purely pathological, and lead to a complete degeneration
of the contents of the oocyst, which shrink and break up, with
production of a great quantity of brown pigment, in a way that
recalls the so-called "black spores" of the Haemosporidia (p. 253).
This is a striking instance of a pathological condition resulting
from a reversion to an ancestral mode of development.

It follows from the homologies put forward above between
the gametes of Coccidia and those of Gregarines, that the cyst of
the latter is a formation functionally analogous, but not phylo-
genetically homologous, to the oocyst of the former. In both
types, however, the contents of the cyst are to be regarded as
equivalent, and the sporoblasts and spores (gymnospores or
chlamydospores) as strictly homologous in the two cases. The
first impulse towards the divergent evolution of the reproductive
phases of Gregarinida and Coccidiomorpha respectively probably
came from the acquisition, by the former, of an intercellular
trophic phase. There is, however, another group, the sub -order
Haemosporea, in which an intercellular trophic phase has been
acquired, and in which similar adaptations in the reproductive
phases might be expected to occur, but since next to nothing is
known at present with regard to the sexual reproduction of these
forms, it is impossible as yet to say how far such expectations are
fulfilled.

SUB-CLASS NEOSPORIDIA.

Sporozoa in which reproduction goes on during the trophic phase.
ORDER 4. Myxosporidia.

The Myxosporidia are one of the most populous and abundant
groups of the Sporozoa, exhibiting a wide range of structural

THE SPOROZOA 275

variations, correlated with great divergence in habitat and mode
of life. They are nevertheless a well-defined and homogeneous
order, characterised more especially by the following points of
organisation and development : — The trophozoite is amoeboid and
Rhizopod-like ; spore - formation commences at an early period
and proceeds continuously during the growth of the trophozoite ;
the spores are produced endogenously, i.e. within the protoplasm
of the trophozoite ; and each spore always possesses one or more
very distinctive structures, the "polar capsules," which have a
strong resemblance to Coelenterate nematocysts. These points
taken together are sufficient to distinguish one of the Myxosporidia
(including under that term the Microsporidia or Glugeidae) from any
other sporozoan type.

(a) Occurrence, etc. — The Myxosporidia, and especially their
spores, figure in older' zoological works under the names either of
" fish-psorosperms " or of " pebrine-corpuscles." The former name,
applied to the sub-order PJuienocystes ( = Myxosporidia sens, strict,
auct.}, arose from the fact that the Ichthyopsida are the group of
animals most favoured by their attentions ; the latter name,
denoting various species of Cryptocystes ( = Microsporidia, Balbiani),
was given on account of the well-known association of one species
with the destructive silkworm-disease, " la pebrine."

The Phaenocystes are pre-eminently parasites of Vertebrata,1 and
especially of fishes. They are not known to occur in Amphioxus,
in Cyclostomes, or in Ganoid fishes, and a few families of Teleostean
fishes, such as the Cycloj)terida€ and Pkuronectidae, apparently do not
harbour any Myxosporidia; but with these few exceptions the
greater number of, at any rate, the commoner species of Elasmo-
branch and Teleostean fishes are subject to their attacks, and not
infrequently one species of fish may be infested by four or five
different species of Myxosporidia. They occur commonly also in
various Amphibia, especially in Anura. In Reptiles they are less
abundant, but Myzidium danileivskyi, Laveran, infests the kidneys of
tortoises (Emys lutaria and Cistudo europaea), and an undetermined
species has been described from the muscles of lizards and tortoises.2
A "psorosperm" is also reported from the crocodile.3 But up to
the present, no Myxosporidia of any kind are known to occur in
warm-blooded Vertebrata, in which the Sarcosporidia seem to take
their place.

The Cryptocystes, on the other hand, are most commonly

1 Exceptions are : — Chloromyxumdiploxys, Thi-lohan ( Cystodiscusdiploxys, Gurley),
discovered by Balbiani in the moth Tortrix viridana ; an unidentified species of
Myxobolus (?) discovered by Lieberkiihn in the Oligochaete Nais lacustris, and
figured by Biitschli, Bronn's "Thierreich," PI. 38, Fig. 23 ; and the organisms described
by Stole as Actinomyxidia from aquatic Oligochaeta (vide p. 298 infra).

2 Danilewsky, 1891, and Pfeffer, 1893 ; see Thelohan [113].

3 Solger, 1877 ; see Gurley [102].

276 THE SPOROZOA

found infesting Invertebrate hosts, and especially Arthropods.
Hence they were termed by Balbiani " psorospermies des Articules."
But they have also been found in other classes of animals both
Invertebrate and Vertebrate. Glugea laverani, Caull. et Mesn., infests
two species of Polychaetes ; an undetermined species of Pleistoplwra
has been found by Leger (1897) in a Trematode (Brachycoelium sp.);
Glugea Iielminthophthora (Kef.) is found in tapeworms, Taenia spp.,
and in Nematodes (Ascaris mystax) ; Glugea bryozoides (Korot.), Thel.,
has been described by Korotneff from the Bryozoan Akyoncellum
fungosuin ; while a number of species of Glugea and Pleistoplma are
known from various fishes. The range of this sub-order is there-
fore wide, and future researches will probably show it to be even
more extended than it is known to be at present.

(b) Habitat, Effects on tJieir Hosts. — The Myxosporidia, taken as
a whole, seem to be more efficient than any other group of Sporozoa
in impairing the health and vitality of their hosts, and are often
the cause of the most virulent epidemics. The ravages of the
pebrine disease amongst silkworms, caused by Glugea bombycis, is
perhaps the most familiar example of their destructive powers, but
many other instances could be cited, especially the frequent
epidemics amongst fish caused by Myxosporidia both in Europe
and America. The destruction wrought by Myxobolus pfeifferi
amongst barbel, and by M. cyprini amongst carp, in the rivers of
France and Germany, has caused a good deal of attention to be
directed to the parasites in question, and in the case of the former,
the investigations of Hofer and Doflein elicited some interesting
facts. The barbel were found to be infested Avith the Myxobolus in
all the rivers of Germany, but while in certain rivers, particularly
in the Moselle, the parasite is endowed with powers so deadly that
the barbel are killed off in thousands, elsewhere it is comparatively
innocuous. The epidemics amongst crayfishes in France, caused by
TMlohania contejeani, also deserve special mention. The economic
importance of the Myxosporidia has led to their being the object
of thorough and extended investigations in recent times. Ten
years ago the Myxosporidia were an obscure group of which
comparatively little was known ; at the present day, though much
remains still to be studied, they are perhaps more thoroughly
worked out, and on the whole better understood, than any other
section of the Sporozoa. To this result, the careful and laborious
researches of Thelohan, Gurley, and Doflein have contributed more
especially.

In the bodies of their hosts the Myxosporidia attack a variety
of organs. The PJiaenocystes are typically intercellular parasites,
while the Cryptocystes commonly infect cells, but in the former
sub-order the trophozoite in its earliest stages may occur either
within or between cells (Doflein). The distinction has not,

THE SPOROZOA 277

therefore, the importance often attributed to it. A large number
of forms are tissue parasites, especially the numerous species of
Mi/xobolidae amongst Phaenocystes, and many Cryptocystes. Hence
the Myxosporidia, together with the Sarcosporidia, have been termed
Histosporidia (Labbe) or Histozoa. These terms cannot, however,
be used in any but a physiological sense, as a great many Phaeno-
cystes, especially in the families Myxidiidae and Chloromyxidae, occur
floating freely in the internal cavities of certain organs. It is
therefore more convenient to distinguish at the outset between
species living freely, on the one hand, and those infecting cells or
tissues, on the other hand. The "free" species occur more
particularly in the cavities of biliary or urinary organs in Vertebrate
hosts ; that is to say, in the gall-bladder, bile-ducts, urinary bladder,
or kidney- tubules. No species are known, however, which, like the
Gregarines, occur free in the alimentary canal or in the general
body-cavity of their host during the trophic period of the life-
history. In the organs which they affect they are found floating
freely in the urine or bile, or attached by their pseudopodia to
the lining epithelium, but they do not injure the cells themselves,
except indirectly, as, for instance, when they may be so numerous
in a kidney - tubule as to obstruct the lumen, with pathological
consequences to the organ. The species which attack tissues and
cells may occur in all parts of the body, infesting usually either
connective or muscular tissue. The only classes of tissue exempt
from their attacks, so far as is known, are bone and cartilage. They
are not known to occur in the testis of any host, and though they
frequently attack the connective tissue and stroma of the ovary,
they rarely penetrate the ovarian follicles, which happens, however,
in the case of the silkworm -moth, with the result of producing
hereditary infection. Nervous tissue also is very seldom affected
by these parasites, but Glugea lophii, Dofl., attacks the ganglion- cells
of Lophius piscatorius. It is amongst the tissue -infecting Myxo-
sporidia that the most injurious parasites occui\ A given species
may either restrict its attacks to one particular organ or tract, or
it may ravage impartially almost all parts of the body, and as a
rule the destructiveness of a parasite is directly proportional to the
extent of its range within the body of the host. In some cases,
for instance, in that of Myxobolus pfeifferi of the barbel disease,
bacteria have been suspected of aiding the Myxosporidian parasite
to produce its fatal results ; but according to Doflein, bacteria do
not occur in the tumours produced by the Myxobolus until they
have reached the stage of suppuration.

The tissue-infecting forms fall naturally into two subordinate
categories. " In the first place, the attacks of the parasite may be
concentrated at one spot, in which case a cyst is usually formed round
it by the adjacent tissues (Fig. 81). Within the cyst, the body of the

278

THE SPOROZOA

Myxosporidian may exhibit a certain amount of differentiation at

its outer surface to form a limiting
membrane or envelope. In the
second place, the parasite may be
spread over a considerable area of
the tissue infected, producing the
condition aptly termed by Thelohan
that of diffuse infiltration (Fig. 82).
In this case, the protoplasmic body of
the parasite and the cells of the tissue
are inextricably commingled, and as
the former is gradually used up to
form spores, a condition is finally
reached in which the tissue is found
to be infiltrated with vast numbers
of spores lying isolated from one
another, or in groups between the
cells. The concentrated condition of
the parasite is usually distinctly
visible to the naked eye, as little

gpots jn th(J tissues . the diffuse COn-

dition requires microscopic investi-
gation in order to discover the parasite. Some species occur
indifferently in either state, others only in one or the other
condition.

FIG. Si.

Transverse section of a stickleback
(Gasterosteus aculeatus), showing two
cysts of Glugea anomala, Moniez (KK),
in the body musculature on the right
(From Wasielewski, after Thelo-

Associated with the parasites in the tissues there are frequently to
be found large numbers of "yellow bodies," the nature of which is
doubtful ; whether, that is to say, they are products of the parasite or of
the host. They are often very conspicuous, and often enclose spores (see
Doflein [100]).

An interesting fact was brought to light by Hofer and Doflein with
respect to the destructive " Pockenkrankheit " of the carp. The disease
shows itself in the form of large indurated tumours of the skin, consisting
of epithelial growths which are invaded by leucocytes and by a prolifera-
tion of blood-vessels from the cutis. The most careful search failed,
however, to discover parasites or intruding organisms of any kind in
these tumours, but in all the diseased fish Myxobolus cyprini was found to
occur plentifully in the spleen, liver, and kidneys. Hence these authors
explain the skin-eruption of the carp as an indirect effect of the inter-
ference with the metabolism caused by the presence of the parasite in the
internal organs, more particularly in the kidney. This view has, however,
been sharply criticised, especially from the medical side (see Liihe [5],
pp. 85, 86).

(c) Morphology. (1) The Trophic Stage. — The trophozoite of the
Myxosporidia is remarkable, as has been said, for its amoeboid form
and Rhizopod-like appearance. In all but very young forms, the

THE SPOROZOA

279

body is divisible into two distinct regions, a denser external
ectoplasm, clear and very finely granular, enclosing a more fluid
endoplasm, which is opaque and coarsely granular (Figs. 83 and 84).

FIG. 82.

Section of the wall of the urinary bladder of a tench, showing Myxobolus ellipsoides, Thel.
(myx), occurring in the condition of diffuse infiltration between the bundles of connective tissue
(c.t). (From Wasielewski, after Thelohan.)

The ectoplasm is the seat of movement, and the pseudopodia take
origin from it, but it also has a protective function, well seen in the
forms inhabiting bile or urine, which disintegrate if the ectoplasm

set

Fio. 83.

Trophozoite of Chloromyxum leydigi,
Ming. (par. Scyllium, Raia, etc.), in a
condition of activity, ect, ectoplasm ;
ps, pseudopodia ; end, endoplasm ;
y, yellow globules in the endoplasm ;
sp, spores, each with four pole capsules.
(After Thelohan, x 525.)

Trophozoite of Sphaerospora divergens, Thel. (par.
Blennius and Crenilabnts). Letters as in Fig. 83.
(After Thelohan, from Wasielewski, x 750.)

be damaged. The endoplasm, besides vacuoles, granules of various
kinds, and sometimes crystals, contains the nuclei, and spores in
all stages of development.

280

THE SPOROZOA

The pseudopodia are easy to observe in the free forms, but are
less easily studied in the tissue-infecting species. They vary in form
from lobose, rounded projections to slender or even filamentous
processes, which may unite
longitudinally, but never
form reticular anastomoses
(compare Figs. 84 and 86).
They usually arise from the
ectoplasm alone, but some-
times are formed as out-
growths of the whole body
substance (Fig. 85). In
many species, especially of
Disporea, the pseudopodia
are localised at the extremity
which is anterior in locomo-
tion (Fig. 87). In some of the
forms which exhibit localisa-
tion of this kind, the anterior
pseudopodia are not the

FIG. 85.

Spore - bearing trophozoite of Cerato-
myxa appendiculata, Thel. (par. Lophius
spp.). ps, pseudopodia ; end, endoplasm ;
sp, spores. (After Thelohan.)

FIG. 86.

Spore -bearing trophozoite of Leptotheca agilis,
Thel. (par. Trygon and Scorpaena). ps, pseudopodia
localised at the anterior end ; f.gr, fatty granules
similarly localised ; r.gr, refringent granules ; sp,
spores, two in number. (After Thelohan, x 750.)

principal agents in forward movement, but appear to be thrust out
more or less tentatively, as it were, and progression is effected
in the following remarkable manner. A strong tail-like pseudo-
podium grows out from the posterior end, which, as it is formed,
pushes the body forwards (Fig. 87, c). The anterior pseudopodia at
the same time bend round and elongate in proportion as the animal
advances. The extension of the propulsive pseudopodium is accom-

THE SPOROZOA

281

panied by the excretion of a granular substance which is left behind
as the animal moves forwards. Locomotion effected in this manner,
by means of a posteriorly situated propulsive pseudopodium
(" Stemm-pseudopodium," Doflein) is unique amongst Protozoa, and
possibly represents a primitive method of progression, which in
the non-amoeboid Telosporidia is reduced to the shooting out of a
secretion alone, without any extension of protoplasm, from the
posterior end (see p. 181).

The pseudopodia, whatever their characters, are never used for
the ingestion of solid food-particles, as in Amoebae. In free forms,
however, they serve for fixation, as well as for movement. Besides

. 'St pS.

FIQ. 87.

Leptotheca agilis, Thel., young trophozoites in which spore-formation has scarcely commenced,
after Doflein. a and b, two figures of the same individual drawn at intervals of rather more
than a minute, c, an individual moving forward (in the direction of the arrow) by means of a
propulsive pseudopodium (st.ps) at the hinder end ; the trail of granules left by the
propulsive pseudopodium should be represented much longer, ps, pseudopodia ; st.ps,
propulsive pseudopodium ; p.sp, pansporoblast.

amoeboid changes of form, the trophozoite may exhibit contractile
movements like those of Gregarines, resulting in ring- like con-
strictions or flexions of the body.

In many cases, especially amongst encysted forms, the ectoplasm
has its protective function developed at the expense of its motility,
and becomes converted into a firm envelope, which may be finely
fibrillar, as in Glugea anomala, or vertically striated, as in Myxidium
lieberkuhnii (Fig. 88). In the last-named species the character
of the ectoplasm is variable, and in other cases it may give rise to
lobose pseudopodia, or be covered with a sort of fur of fine
non-motile filaments. These differentiations of the ectoplasm are
important for comparison with the envelopes of the Sarcosporidia.

The endoplasm has a distinctly alveolar structure, and is some-

282

THE SPOROZOA

times vacuolated, and often coloured. It contains numerous
enclosures and metaplastic products, most frequently of an oily
or fatty nature, representing probably reserve nutriment. In the
youngest trophozoites there is but a single nucleus, but with
growth of the parasite the number of nuclei lodged in the

Fio. 88.

Extremity of a trophozoite
of Myxidium lieberkiihnii,
Biitsch'li (par. Esox and Lota),
in which no spores are as yet
formed, x 750. e, e', ecto-
plasm, homogeneous at e,
vertically strutted at e' ', n,
nuclei ; g, globules of fat
blackened by osmic acid.
(After Thelohan, from Wasie-
lewski.)

endoplasm continually increases by their division, until many are
present in the full-grown forms. The number is smallest in
disporous forms (infra, p. 283), where it may be no more than ten,
but usually it is much greater than this. The nuclei are very minute
as a rule, generally not more than 1-2 //, in diameter, but they
sometimes differ markedly in size in the same individual. Each
nucleus consists in typical instances of a deeply-staining membrane
enclosing a reticular framework, on which the chromatin is partly

"AU:

a b c d e

FIG. 89.

Stages in nuclear division in Chloromyxum leydigi, Ming. The resting nucleus (a) contains
chromatin granules and a " chromatosphere." Preparation for division commences (ft) by the
breaking up of the chromatosphere. In the next stage (c) the chromatin collects towards the
transverse plane of the nucleus, to form (d) the equatorial plate, which splits to furnish the
chromatic substance of (e) the two daughter nuclei. (After Doflein.)

diffuse, partly aggregated towards the centre to form a " chromato-
sphere." True nucleoli or karyosomes are not found. The division
of the nuclei takes place by a form of karyokinesis, but without
asters or centrosomes (Fig. 89).

(2) Spore-Formation. — The spores commence to develop at an
early stage in the growth of the trophozoite, and in some species
they continue to be formed until the whole of the substance of the
trophozoite is used up in their production. In other cases, how-
ever, the volume of the reproductive bodies is small in comparison
with that of the whole body. The spores may be few in number,

THE SPOROZOA

283

no more than two being formed in some genera, hence termed
disporous, but more usually they are produced in great numbers,
and all stages of the development of the spores are commonly to be
found present at the same time in a given individual. Since,
therefore, sporulation does not, as in Telosporidia, indicate a
cessation of growth and nutritive activity on the part of the
parasite, it is not accompanied by encystment of the sporont.
Occasionally, however, the ectoplasm may secrete a gelatinous
envelope, when reproduction commences (e.g. Myxidium giganteum,
Doflein).

In some cases, e.g. Myxidium lieberkiihnii, Biitschli, spore-forma-

vac_

Stages in spore-formation. All the figures are from Myxobolus ellipsoidts, Thel. (par. Tiiica),
except a and /, which are from M. pfeifferi, Thel. (par. liarbus). a, differentiation of the pan-
sporoblast (psp). b, pansporoblast with two nuclei, c and d, pansporoblasts with six and ten
nuclei respectively ; in d, four of the nuclei are degenerating, e, pausporoblast segmented into
two definitive sporoblasts, each with three nuclei. In the next four figures the definitive
sporoblast, or the spore produced from it, is alone figured. /, definitive sporoblast segmented
into three masses, the capsulogenous cells (c.g.c) and the sporoplasm (sp.p), within an envelope,
the spore membrane (sp.7»). g, more advanced stage, k, spore completely developed, with two
polar capsules and sporoplasm containing an iodinophilous vacuole. i, abnormal spore con-
taining six polar capsules. ;«;>, pausporoblast; n, nuclei; sp.bl, definitive sporoblast; r.n,
residuary nuclei ; c.g.c, capsulogenous cells ; sp.p, sporoplasm ; sp.m, spore membrane ; vac,
vacuole ; r.p.c, rudiment of p.c, polar capsule ; n.p.c, nuclei of polar capsules ; iod.vac, iodino-
philous vacuole ; n.sp., nuclei of sporoplasm. (After Thelohan.)

tion has been observed to vary with the seasons, being in abeyance
in the winter, but proceeding actively in the warmer months.

The first sign of spore - formation is the concentration of
protoplasm round one of the nuclei of the endoplasm, to form a
little spherical corpuscle, the pansporoblast of Gurley ("primitive
sphere " of Thelohan). Not all the nuclei of the endoplasm,
however, are used up for the formation of pansporoblasts ; a
certain number may be left over as residuary nuclei, at least in
the Disporea (Fig. 91). The pansporoblast is separated from the
surrounding endoplasm by a thin pellicle or envelope of tougher
protoplasm. In preparations a space may appear round it (Fig.
90, a), which is the result of shrinkage caused by preserving
reagents, and is not present in the living condition. The nucleus

284 - THE SPOROZOA

of the pansporoblast divides repeatedly by mitosis, to form several
nuclei, the normal number being about ten (Fig. 90, b, c, d). The
protoplasm at the same time segments within the envelope into two
masses, the definitive sporoblasts ; this may take place before, or
after, the full number of nuclei are formed in the pansporoblasts.
The two sporoblasts when completely developed have each three
nuclei, since four of the ten original nuclei are cast out as
residuary nuclei, and undergo degeneration (Fig. 90, e). Each
sporoblast now begins to secrete a cuticular spore-membrane at the
surface, and within the membrane the protoplasm segments into
three portions centred round each of the three contained nuclei
(Fig. 90, /). Of the three corpuscles or cells thus formed, two are
rather smaller than the third ; the former are the two capsulogenous
cells; the larger corpuscle is the spwoplasm, and its nucleus divides
into two, a division which sometimes takes place at an earlier stage,
so that the undivided sporoblast may contain four instead of three
nuclei.

Each capsulogenous cell gives rise to a polar capsule in the
following way. A clear spherical vacuole first appears near the
nucleus of the cell. At some point, which is not constant, in the
wall of the vacuole, a bud of protoplasm grows into the interior of
the vacuole, pushing aside the clear substance contained in the
latter (Fig. 90, g). The bud of protoplasm becomes a little pear-
shaped body, surrounded by a, clear envelope which is derived from
the contents of the vacuole. At first connected by a stalk with the
point at which it took origin, the pear-shaped body becomes free
through severing of this connection, and then takes up a definite,
specific orientation with regard to the spore as a whole (Fig. 90, h).
At the surface of the pear-shaped body a membrane is formed, and
in its interior a spirally-coiled filament is developed. The polar
capsule, when fully formed, has a striking resemblance to a
Coelenterate nematocyst, since the coiled thread can be shot out
upon suitable stimulation (Fig. 97). Round the polar capsule are
found the remains of the capsulogenous cell and its nucleus, but
they soon degenerate and disappear.

When the development is completed, there are found, still
contained in the envelope of the pansporoblast, two spores, each
enclosed in a tough membrane, within which are the polar capsules
and a little binucleate mass of sporoplasm which represents the
single sporozoite. The envelope soon breaks down, and the spores
are then found scattered in the endoplasm of the trophozoite.

The development above described is that typical for the Phaenocystes,
but even in this order there is considerable variation, and in the
Cryptocystes the deviations from the type above described are still more
pronounced.

In the Phaenocystes, apart from individual abnormalities (Fig. 90, i),

THE SPOROZOA

285

which are frequent, the chief developmental variations are seen in the
number of polar capsules, of which there may be only one, or as many as
four. The latter number characterises the Chloromyxidae, and in this
family twelve or fourteen nuclei are found in the pansporoblast, and five
or six in each definitive sporoblast (Doflein [100]).

In the Cryptocystes the pansporoblast always gives rise to more than two
spores, namely, to four in Gurleya, eight in Thelohania, and to a large number
in Pleistophora and Glugea. Further peculiarities
are seen in the origin of the pansporoblast in this
sub-order. In Glugea, numerous pansporoblasts
are formed in each trophozoite, just as in the
polysporous Phaenocystes, but in Gurleya, Thelo-
hania, and Pleistophora, the whole trophozoite
becomes converted into a single pansporoblast, thus
producing a state of things which only differs from
Coccidium or any other Telosporidian type in the
fact that the spores are formed endogenously, in
the bosom of the protoplasm, and not at its outer
surface. An approach to this condition is also
seen in the disporous Phaenocystes, where only one
pansporoblast is formed in each trophozoite, the
remaining protoplasm, with the contained nuclei,
being left over as residual protoplasm which dies
off ultimately (Fig. 91). It would not be safe,
perhaps, to regard these forms which produce a
single pansporoblast as connecting links in any
way between the Telosporidia and the Neospo-
ridia, but they are certainly suggestive in con-
sidering the relationship between these two sections .
of the Sporozoa. The Myxosporidia might be letters as before.
regarded as forms in which the trophozoite pro-
duces typically a greater or less number of sporonts (i.e. pansporoblasts)
by a process of internal gemmation. On this view, the typical life-cycle
of the Myxosporidia would represent an alternation of generations between
trophic and reproductive individuals.1

The development of the pansporoblast or sporont of Thelohania miilkri
has been followed in detail by Stempell [111]. The nucleus divides
without mitosis into eight nuclei, round which the protoplasm becomes
segmented to form eight sporoblasts, imbedded in an intercellular residuum
within the envelope of the sporont (Fig. 92, a-i). Each sporoblast becomes
a spore, which has first one nucleus, later two (Fig. 92,j-l). Stempell
has made the further remarkable discovery, that when a fresh host
(Gammarus) is artificially infected, the spores remain some time in the
gut before germinating, during which period the two nuclei divide, 'so
that the spore ready to hatch has four nuclei (Fig. 92, m).

1 Since this paragraph was written (in 1901), Stempell [111, p. 265] has dis-
cussed the relation between "sporont" and "pansporoblast," and has suggested
that the sporonts of Thelohania and similar forms are " pansporoblasts which in the
course of the phylogenetic development have become independent individuals."

Fio. 91.

Ceratomyxa inaequalis,
Dofl. (par. Crenilabrus), tro-
phozoite containing two

(After

286

THE SPOROZOA

(3) Morphology of the Spore. — In their external form and
structural details the spores of Myxosporidia show great variability,
and furnish useful characters for purposes of systematic classifica-
tion. The spore -membrane is composed of a transparent, homo-
geneous substance, of doubtful chemical nature, and remarkable for
its resistance to the action of reagents. It has the form of two

FIG. 92.

Spore - formation in Thdohania
millleri (L. Pffr.). a, sporont with
single nucleus ; b, c, division of the
nucleus ; d, first division of the
sporont ; e, the two nuclei commencing
to divide again ; /, further stage, the
cells beginning to divide again ; g, four-
cell stage ; h, sporont containing eight
cells — sporoblasts — embedded in an
intercellular residuum ; i, the sporo-
blasts becoming spores ; j, spore with
single nucleus ; k, nucleus of the spore
dividing ; I, spore with two nuclei ; ra,

gj & H spore which has been three days in the

^ gut of a new host, and which has four

// / /// nuclei. After Stempell [111], x 2250.

valves meeting in a suture, along which the spore opens to permit
the escape of the sporozoite. The spore, as a whole, is very minute
in the Cryptocystes (4/^x3^ in Glugea anomala, 2'5,/tx 1*5 /4 in
G. ovoidea), and in this sub-order is uniformly pear-shaped. In the
Phaenocystes, on the other hand, the spore is larger, and often of
considerable size (100//,xl2/u,in Ceratomyxa sphaerulosa), and it is
always distinctly bilaterally symmetrical about the sutural or vertical
plane. In Leptotheca and Ceratomyxa the spore is elongated in a

FIG. 03.

Spore of Ceratomyxa sphaerulosa, Thel. (par. Mustelus and Galeus), x 750, after Thelohan.
sp.p, sporoplasm ; p.c, polar capsules; s, suture; x, "irregular, pale masses, of undetermined
origin."

direction at right angles to the plane of symmetry (Fig. 93) ; but
in Myxidium, Henneguya, and most other genera of Phaenocystes, the
longest axis of the spore lies in the plane of the suture (Figs. 95,
99, 107, etc.); a position intermediate between these extremes is
occupied by the nearly spherical spores of Sphaerospom (Fig. 106).
The spore-membrane may be prolonged into tails or processes of
various kinds (Figs. 108, 112, etc.), which may attain a consider-
able length, in which case they are found coiled round while still

THE SPOROZOA

287

within the pansporoblast envelope (Fig. 96), and become straightened
out when set free from it.

The polar capsules are fixed to the valves of the spore-membrane

Fio. 94.

Abnormal spore of
Ceratomyxa truncata,
Thel. (par. Clupea pil-
chardus), with three
polar capsules and
three valves, after
Thelohan. s, suture.

Fio. 95.

Spores of Sphaeromyxa balbmnii,
Thel. (par. Motetta and Cepda),
X 1500, after Thelohan. a, in the
fresh condition ; 6, fixed and stained,
showing nuclei, p.c, polar capsules ;
n.p.c, nuclei of polar capsules ; n.sp,
nuclei of sporoplasin.

close to the suture, and communicate each with the exterior by a
fine canal, through which the coiled thread in the interior of the
capsule can be shot out (Fig. 97). The natural stimulus which effects

FIG. 9(1.

Two sister spores of Cerato-
myxa linospora, Dofl. (par. Labrus
turdus), still enclosed in envelope
of the pansporoblast, showing
the manner in which the long
processes of the spore are curled
round within the envelope.
(After Doflein.)

the discharge of the polar capsules
is found in the digestive juices
of the specific host infected by
the parasite (see below, p. 290),
but the same result can be
brought about artificially by a
number of reagents, such as ether,
glycerine, boiling water, various acids, etc. When there is
only one polar capsule, it marks a point commonly termed an-
terior. When there are two capsules, they may either be close
together at the anterior pole, as in Myxobolus, etc. (Fig. 99),

Fio. 97.

Polar capsules of Myxobolus ellip-
soides, to show the ejection of the
filament. (From Wasielewski, after
Balbiani.)

288

THE SPOROZOA

or they may be situated at the two opposite poles, then termed
inferior and superior, as in Myxidium (Fig. 107); perhaps a good
example of a distinction without a difference. In Chloromyxidae
four capsules are found, which again may be in one group at
the anterior pole (Fig. 108), or disposed in two pairs at opposite
extremities, after the fashion of Myxidium.

In Glugeidae the spores are remarkable for the fact that the single
polar capsule is invisible in the fresh condition of the spore, hence the
name Gryptocystes. It can, however, be demonstrated either by provoking
the extrusion of the filament or by the action of certain reagents which
render it distinct. The presence of a polar capsule in the spores of the
Glugeidae was first made known by Thelohan, a discovery which threw

p.c.

Spores of Glugea 6om-
byeis, Balbiani (par. Bom-
byx mori, etc.) a, 6,
spores seen in the fresh
condition, x 1500. c, d,
spores treated with nitric
acid, which causes them
to swell up a7id increase
in size by a half, at the
same time rendering the
polar capsule distinct.
In d the filament is ex-
truded.

FIG. 99.

Spores of Myxobolus miilleri, Butschli
(on the left), and Henneguya psorosper.
mica, Thel. (on the right), treated with
iodine solution to show the manner in
which this reagent colours the iodino-
philous vacuole (iod.vac) characteristic
of the Myxobolidae. p.c, polar capsules ;
pr, tail-like process. (After Thelohan,
X 1500.)

light on the relationship of these forms, and led to the amalgamation in
modern classifications of the Myxosporidia (Phaenocystes) and Microsporidia
(Cryptocystes), formerly regarded as equivalent orders.

The polar capsules are a very remarkable and distinctive feature
of the spores of Myxosporidia, and have often been misunderstood.
Mingazzini, for example, mistook them for the true sporozoites. It is
nevertheless possible that the polar capsules may represent sporozoites
modified and specialised for a particular function (for which see below,
p. 290), as suggested by Delage. It is difficult either to criticise or to
support this view until more is known of the relationship between the
Myxosporidia and other types of Sporozoa.

The sporozoite, or sporoplasm, consists of a finely granular mass
of protoplasm. There is never more than one such body, which
has constantly two nuclei in Phaenocystes. In Cryptocystes, as we

THE SPOROZOA 289

have seen, the nucleus, at first single, divides twice to produce four
nuclei (p. 285 supra). The sporoplasm generally fills the spore
completely, but in Ceratomyxa it is relatively small, and lodged in
one valve of the shell (Fig. 93). In the family Myxobolidae the
sporoplasm contains a peculiar vacuole, enclosing a substance which
stains a reddish brown with iodine, and exhibits some of the
reactions of glycogen (Fig. 99). No such vacuole is found in the
other families of Phaenocystes, but in Glugeidae a clear vacuole is
almost constantly present at the broader (posterior) extremity,
which does not, however, exhibit any characteristic reactions.
Besides this the sporoplasm of Glugeidae often contains numerous
fine fatty globules.

(d) Development of the Spores; Infective Processes. — The develop-
mental period which intervenes between the ripe spores and the
youngest trophic stages, is the least known period of the life-cycle,
as in all other Sporozoa, but the observations of Thelohan and
Doflein make it possible to form a tolerably clear idea of the events
that take place. The spores are set free from the parent trophozoite,
apparently, by the death and disintegration of the latter in all cases,
and we have next to consider the paths by which they leave the
body of the host. In this process we may distinguish conveniently
between natural and non-natural modes of exit. Thus in the case
of species which live in the gall or urine of their hosts, the spores
doubtless pass out of the body by natural channels. In the case
of tissue-infecting forms, if the cysts are formed near the surface of
the skin or the lining of the alimentary canal, they may excite sup-
puration, and so work their way to the adjacent surface when the
abscess bursts, setting free the contained spores. In both these
cases the death of the host is not necessary in order that the spores
may be set at liberty ; in the first case the host is not inconvenienced ;
in the second case a certain amount of damage is done, but not
necessarily enough to destroy the host, which may live to harbour
other parasites and to disseminate more spores. But in the case of
species inhabiting more deeply situated tissues, the spores can only
be set free by the death and disintegration of the host, and if this
event be too long delayed, the result is fatal to the parasite ; that
is to say, the spores, if retained too long within the body of the
host, pass their prime and die, as is so frequently the case in other
Sporozoa which cannot leave the body of the host by natural means.
The spores never, apparently, develop further in the host in which
they are formed.

The spores when set free sink to the bottom of the water, when
the host is an aquatic animal, or in other cases, as in that of the
silkworm, are left lying about in the host's usual haunts. The
infection of a new host is apparently always a casual one. The
ingenious experiments of Thelohan [113] showed that the spores must

19

2go

THE SPOROZOA

be swallowed by the new host with its food, in an accidental manner,
and pass into its alimentary canal ; then, and not till then, under
normal circumstances, does germination commence. Attempts to
produce infection by direct inoculation, by means of intermediate
hosts, or in other ways, were wholly unsuccessful. The first effect
of the action of the digestive juices is the extrusion of the filaments
of the polar capsules, which appear to act as organs of fixation,
attaching the spore to the epithelium of the digestive tract. The
two valves of the spore-membrane then separate along the suture
and permit the escape of the contained sporozoite, which emerges
as a minute amoebula and penetrates the wall of the digestive tract.
From this point the tiny parasite embarks upon migrations, in some
cases very extensive, in order to reach the organ or tissue which is
its final destination. It is not possible to state with any certainty
how these migrations are either effected or guided. In some cases
the journey is perhaps performed on foot, as it were, the little
amoeboid germ pushing its way actively through the tissues, like a
leucocyte. In other cases the parasite may be passively transported
by means of the blood-current. The latter method is probably the
more usual, the little germ being carried along suspended in the
blood-plasma ; at any rate, there is no evidence that it ever attacks
the blood-corpuscles. The one thing certain with regard to this
stage of the life-history is that the parasite is able to select and to
seek out, in some mysterious fashion, the specific organ or tissue
which it affects, and which may be situated at a considerable
distance from the original seat of infection.

Finally, it should be noted that in Glugea bombycis of the silk-
worm disease, hereditary infection is effected by the penetration of
the parasite into the ovary and the formation of spores within the
ovum itself. Thus the newly -hatched silk-
worms are already infected with the disease
and disseminate it amongst healthy indi-
viduals. No other case of this kind is known
in the Myxosporidia, nor indeed in the whole
of the Sporozoa, with the possible exception
of the parasites of Texas-fever (p. 262). In
Glugea bombycis the infection of older cater-
pillars is effected exclusively by the accidental

\

FIG. 100.

Kidney-ceils of the carp ingestion of spores along with the food, so that
rfj^JffiSrtS^C here too casual infection is the normal type,
rahidiy *myx The^fnyxJf supplemented by hereditary transmission of

sporidian germs ; n, nuclei the disease-germs.

of the kidney-cell. (After / \ a 7 • j n/r 12- ?• i- n

Doflein.) (t) SCRUogOMf and Multiplicative Processes. —

When the amoebula reaches its definitive

situation, it invades the tissues and commences to feed and to

multiply endogenously with great activity. It is probable, how-

THE SPOROZOA

291

l%b-~

ever, that before the parasite arrives at its destination, it goes
through developmental processes of which it is only possible as
yet to form a conjecture. Doflein has drawn attention to the
noteworthy fact that while the sporozoite of the Phaenocystes always
contains two nuclei, the youngest observed trophic stages have but
a single nucleus, and he has suggested that this difference is due
possibly to conjugation, leading to an exchange and subsequent
fusion of nuclei, taking place between the free amoebulae. No con-
jugation has been observed as yet in any stage of the life-history, and
this fact makes it the more probable that some form of conjuga-
tion takes place at a very early stage, having in view further the
great reproductive powers which these parasites exhibit even in the
youngest stages of development. Conjugation at this early stage
would find a parallel in the frequently occur-
ring conjugation between swarm spores in
many Rhizopods.1

Like many other Sporozoa, the Myxo-
sporidia possess the power of endogenous
reproduction within the host, as well as of
exogenous reproduction by means of spores.
Doflein has aptly distinguished these two
modes of reproduction as the multiplicative
and the propagative methods respectively. The
former is comparable in a general way to the
schizogony of Telosporidia, though differing
in details. It has long been suspected to
occur in the Myxosporidia on account of the

vncf niimViPr r>f n-nvicitpo tfinf rrmv VIP nrp^PTit

vast numoer 01 parasites tnat may oe pre AIL

in a given host, and the difficulty of supposing schii (par. ESOX and Lota),

... * • • fj • after Conn, ft buds; end,

that each parasite could have originated in endopiasm ; the clear outer
each case from a separate and independent g^ rePres
spore infection. It is only in recent years,
however, that it has been demonstrated by Cohn [99] and Doflein
[100] in various forms. Multiplicative reproduction may take
place in one of two ways. In the first place, it may go on in the
full-grown trophozoite, either by simple binary fission, similar in
externals to that of an ordinary amoeba, or by the formation of
buds from the protoplasmic body.2 Doflein has termed this process

Fio. 101.

Formation of buds by
multiple plasmotomy in
Myxidium lieberkuhnii, Biit-

1 According toStempell [111, p. 262, footnote], Schaudinn has observed " copula-
tion of the amoeboid germs of a spore " (sic) in Glugea bombycis. The publication" of
these observations will be awaited with interest. Stempell considers that the four
nuclei seen by him in spores previous to germination (p. 285 supra, Fig. 92, m) re-
present a process of nuclear reduction preliminary to the conjugation.

2 Laveran and Mesnil [106], however, deny that the budding described by
Cohu occurs. They find that in Myxidium lieberk'dhnii endogenous multiplication
goes on by equal or subequal plasmotomy in young trophozoites, and that these
small forms often attach themselves to the surface of the body of large individuals,

THE SPOROZOA

plasmotomy, defined as the breaking-up of a multinucleate cell into
multinucleate fragments ; the plasmotomy may be either simple,
i.e. ordinary fission, or multiple, as in budding (Fig. 101). This
mode of reproduction is probably common in the free forms.

In the second place, multiplicative reproduction may take place
in the youngest stages of the parasite, in the amoebula which has

3|g£"-y •;•;. ;

'b" : V

; v-/
d

*

FIG. 102.

Stages of multiple amitosis in the youngest germs of Glugea lophii, Dofl. (After Doflein.)
(The stages given here are those of a division into four, but the products of division may exceed,
or fall below, this number.)

just reached its definitive situation. The nucleus of a minute
individual undergoes a fragmentation into numerous daughter
nuclei by a process of "multiple amitosis" (Fig. 102). The proto-
plasm then breaks up to form numerous minute uninucleate " swarm-
spores," which spread the infection in the tissues of the organ

Schizogony of Thelohania miilleri (L. Pffr.). a, "meront" with single nucleus; b and c,
division into two ; d and e, into four ; /, g, h, chains of meronts formed by rapid division.
After Stempell, x 2250 (see footnote).

affected, or it may be in all the tissues of the host, which in this
way may be soon quite overrun by the parasite when once infected.
This method of reproduction is probably very common, if not uni-
versal, in the tissue and cell-infecting Myxobolidae and Glugeidae.1

thus giving rise to an appearance erroneously interpreted by Cohn as budding
(compare Fig. 101). This method of reproduction goes on actively during the
winter months, when no spores are produced.

1 In Thelohania miilleri (L. Pffr.), from the muscles of Gammams pulex, Stempell
(Zool. Anzeiger, xxiv. p. 157) finds two kinds of trophozoites — larger sporonts, which
produce spores, and smaller meronts, which multiply by a simple form of schizogony.
Each meront divides into two after direct nuclear division, but before the separation
of the two cells is complete, further division is commenced, so that three or four in-
dividuals are found connected in a group. This method of reproduction is clearly
intermediate in character between the two methods, plasmotomy and formation of
swarm-spores, described above.

[Since this note was written, Stempell's detailed memoir has appeared [111], from
which Fig. 103 is reproduced.]

THE SPOROZOA

293

Genus 2. Leptotheca, Th4L,

CLASSIFICATION.
ORDER Myxosporidia, Biitschli.

SUB-ORDER I. PHAENOCYSTES, Gurley ( = Myxosporidia sens, strict.}.
Spores relatively large, bilaterally symmetrical, with two or four polar
capsules, which are plainly visible in the fresh state. (Two anomalous
species of Myxobolus have but a single polar capsule in the spore.) Two
spores are formed in each pansporoblast. The trophozoite is an inter-
cellular parasite in all but the earliest stages.

(a) Disporea, Doflein. Only two spores (i.e. one pansporoblast) are
produced in each trophozoite. The greatest length of the spore is at right
angles to the plane of symmetry, i.e. the sutural plane. Typically " free "
parasites (see p. 277).

FAMILY 1. CERATOMYXIDAE, Doflein. With characters as above.

Genus 1. Geratomyxa, Thdl., 1892. The valves of the spore-membrane
have the form of hollow cones, the extremities of which are prolonged into
more or less attenuated processes (Fig. 93). About nine species are
known, all from the gall-bladders of fishes. Type-species C. sphaerulosa,
The"l. (Fig. 93), from Mustelus and Galeus.
1895. The valves of the spore
membrane are not produced
into long processes as in the
preceding, and the sporoplasm
fills the whole space within the
spore-membrane not taken up
by the polar capsules (Figs.
104, 105). Six species are
known, four inhabiting the ?,p.orl,.?f, i^&otheca

' . u-i •**"* T1161- (Par- Trygon

gall-bladders Of fishes, While andScorp«€na),seenmthe

L. ranae, Thel., occurs in the ^ff?6^^*^,

kidneys of Rana esculenta and suture ; p, sporoplasm. Gurley] " (par. Acerind
T, • T • 7 (From Wasielewski, after cernua). (From Wasie-

B. temporana; L. remcola, Thelohan.) lewski, after Balbiani.)

The"!., in the kidney-tubules

of the mackerel. Type-species L. agilis, Thel. (Fig. 104), from the gall-
bladder of Trygon vulgaris.

(b) Polysporea, Doflein. More than two spores, usually a vast number,
are produced in each trophozoite. The greatest length of the spore lies in
the sutural plane.

While in general the Polysporea and Disporea are distinct enough in
all their characters, a transition between these two sections is furnished
by the genus Sphaerospora, which has nearly spherical spores, and of which
one species, S. elegans, Thel., is disporous.

FAMILY 2. MYXIDIIDAE, Thel. The spores have two polar capsules,
and are without an iodinophilous vacuole (p. 289) in the protoplasm.
Typically " free " parasites.

Genus 3. Sphaerospora, Thel., 1892. (Characters, see above.) Four
or five species are known, mostly from the kidneys of fishes, but

FIG. 104.

FIG. 105.

Spores of Leptothtca
perlata [= Chloromyxum
(Sphaerospora) perlata,

294

THE SPOROZOA

Fio. 106.

S. masovica, Cohn, is found in the gall-bladder of the bream (Abramis

brama), and S. elegans, Thel., from Gasterostens spp., penetrates from the
kidney into the ovarian stroma. Genus 4. Myxidium,
Biitschli. The spores are elongated in the sutural
plane, and fusiform, with a polar capsule at each
extremity (Fig. 107). The polar filaments are long
and filiform. About seven species are known, the
most familiar being M. lieberkuhnii, Biitsch., from the
urinary bladder of the pike. The other species are
mostly from the kidneys or gall-bladders of fishes, but
M. danilewskyi, Laveran, has been described from the
sp.) kidneys of tortoises. Genus 5. Sphaeromyxa, Thel., 1892.
JhanO& '' The spores are fusiform and longitudinally striated,
with truncated ends, and with a polar capsule at each

extremity (Fig. 95). The polar filaments are short and conical. The

trophozoite is generally of disc-
like or lenticular form, with lobed

ectoplasm at the margin. Three

species are known from the gall-
bladders of fishes. Genus 6. Cysto-
discus, Lutz., 1889. Spores oval,

with the sutural plane running

obliquely to the principal axis,

and a polar capsule placed near

each extremity of the spore, but

not quite terminal. Trophozoite

similar to that of Sphaeromyxa.

One species, 0. immersus, Lutz.,

from the gall-bladder of Bufo agua

and Cystignathus ocellatus, in Brazil.

[By Gurley the species Chloro-

myxum diploxys, Thel., is also in-
cluded in this genus, which is

made the type of a family Cysto-

discidae. The genus Sphaeromyxa,

Thel., is also referred by him to

this family, but doubtfully. By

Thelohan, on the other hand,

Cystodiscus immersus is referred to po^oif?£\

the genus Sphaeromyxa, and the ES^ftCSro

%:.«•;«- $V

Fio. 107.

Myxidium lieberkuhnii, Biit-
schli, from the urinary bladder
of the pike, a, trophozoite
with two spores and pseudo-
podia, after Lieberkuhn. ft, tro-
phozoite with numerous spores,
c and d, spores, the latter with
extruded polar filaments. 6, c,
and d, after Balbiani. (From
Wasielewski.)

genus Cystodiscus is not recognised.]
Genus 7. Myxosoma, Thdl., 1892.
The spores are flattened, and oval
in outline, with the polar capsules close together at the anterior ex-
tremity. One species, M. dujardini, Thel. (placed by Gurley in the genus
Chloromyxum), from the gills of Scardinius erythrophihalmus and Leuciscus
rutilus. Genus 8. Myxoproteus, Dofl., 1898. Spores roughly pyramidal,
with spiky projections at the upper end (i.e. from the base of the pyramid),
which bears two large polar capsules, separated by an interval equivalent

THE SPOROZOA

295

to their own diameter. One species, M. ambiguus ( = Myxosoma ambiguum,
Thel.), from the urinary bladder of Lophius piscatorius.

FAMILY 3. CHLOROMYXIDAE, Thelohan. Spores with four polar
capsules, and with no iodinophilous vacuole in the sporoplasm. (By
Gurley the name of this family is used in a different sense, and contains
the genera Ceratomyxa and Chloro-
myxum, a sub-genus of the latter being
Sphaerospora, which includes Myxo-
soma.}

Genus 9. Chloromyxum, Mingazzini,
1898, with the characters of the
family. Six or seven species are
known ; type C. leydigi, Ming., from
the gall-bladders of various Elasmo-
branchs (Fig. 108, a). G. caudatum,
Thdl., occurs in the gall-bladder of
Triton cristatus (Fig. 108, 6). C.
diploxys, Thel., infests Tortrix viridana;
aberrant in the matter of habitat, this
species differs also from other species

of the genus in having the four polar «. Chloromyxum Uydigi,J&ing., seen from

r the sutural aspect, X 2250. 6, C. caudatum,

capsules arranged in two pairs at the Thel., x 1900. p.c, polar capsules ; s, su-

nmwuTp pTrrpmiHpq nf trip miorp like ture ;/, filaments ; j>.s, tail-like process of
°PPOS spore, iiKe the gpore enveiope>

a Myxidium with doubled polar cap-
sules. It should probably be regarded as a distinct generic type.

FAMILY 4. MYXOBOLIDAE, Thelohan. Spores with one or two polar
capsules, and with a peculiar iodinophilous vacuole in the sporoplasm.
Typically tissue-parasites, only found in Verte-
brates, with the doubtful exception mentioned
above (p. 275, footnote).

Fio. 108.
Spores of Chloromyxidae, after Thelohan.

Fio. 109.

Spores of Myxololns ellip-
scrides, Thel. The spores on
the left and right are lying
with the sutural plane hori-
zontal, that in the middle
with the sutural plane verti-
cal. (From Wasielewski, after
Balbiani.)

FIG. 110.

Spore of Myxobolus
miUleri, Butschli, in the
fresh condition, x 1500. s,
sutural margin, notched ;
(, triangular appendix of
the valves. The filaments
of the polar capsules are
clearly seen. (From
Wasielewski, after The-
lohan.)

Fio. 111.

Spores of Myxobolus (?)
o&esMSjGurley (par. Alburnus).
(From Wasielewski, after Bal-
biani.)

Genus 10. Myxobolus, Butschli, 1882. Spore-membrane without a
tail-like process, with one or two polar capsules (Figs. 109-111). About

296

THE SPOROZOA

40 species known, but not all named ; found in the gills, fins, scales,
kidney, spleen, etc., of various fishes, usually in the connective tissue
of these parts. The genus is divisible into three sections ; in the
first come the aberrant forms M. piriformis, Thel., of the tench (Tinea
tinea), and M. unicapsulatus, Gurley, from Labeo niloticus, which have
pear-shaped spores, each with a single polar capsule ; in the second are
M. dispar, The"!., from Cyprinus rutilus and Leuciscus rutilus, and M.
inaequalis, Gurley, from Pimelodus blochi and P. clarias, both with two
polar capsules of unequal size ; while in the third section are the very
numerous forms characterised by two polar capsules of equal size, the best
known being M. miilleri, Biitsch., the type-species (Fig. 99), from various

FIG. 112.

Spores of Henneguya psorospermica, Thel.,
from the pike, a and d are seen lying with
the sutural plane horizontal ; 6 and c with
the sutural plane vertical, c is an abnormal
spore.

Fio. 113.

Spores of various Glugeidae, xloOO, after
Thelohan. a and 6, Pleistophora typicalis,
Gurley ; a in the fresh condition, b after
treatment with iodine water, causing ex-
trusion of the filament, c and d, Thelohania
octospora, Henneguy ; a fresh, 6 treated with
ether, e, Glugea depressa, Thel., fresh, f,
G. amta, Thel.

fish (Squalius cephalus, Barbus barbus, Phoxinus laevis, Grenilabrus melops,
Thymallus vulgaris) ; M. ellipsoides, Thel., of the tench (Fig. 109);
M. pfeifferi, The"!., cause of the deadly barbel-disease ; and M. cyprini,
Don., from the carp. Genus 11. Henneguya, Thel., 1892. Spore with
a tail-like process, with two polar capsules (Fig. 112). Four species
are known, two of which infest sticklebacks (Gasterosteus aculeatus
and pungitius) ; a third occurs commonly, with several varieties, in
the pike and the perch. Genus 12. Hoferellus, Berg., 1898, nom. nov.
for Hoferia, Don., 1898. Spore of broad and compressed form, with
two tail-like processes at the posterior pole. One species, H. cyprini,
Don., associated commonly with Myxobolus cyprini in the disease of the
carp.

SUB-ORDER II. CRYPTOCYSTES, Gurley ( = Microsporidia, Balbiani).

THE SPOROZOA

297

Spores minute, pear-shaped, with one polar capsule, which is only visible
after treatment with reagents (Fig. 113). More than two spores are formed
in each pansporoblast. Cell parasites.

FAMILY 5. GLUGEIDAE, Thelohan. With the characters of the sub-
order.

Section a. Polysporogenea, Doflein. The trophozoite produces numerous
pansporoblasts, each of which in turn produces many spores.

Genus 13. Glugea, Thel., 1891. With characters of the section. (The
synonymy of this genus is somewhat involved, and it is by no means
certain that the name most commonly employed has the prior right over
Nosema, Nageli, 1857, or Microsporidium, Balbiani.) A large number of
species are known, from a great variety of hosts, among which Arthropods
and Fishes preponderate. The best known species is the destructive
G. bombycis of the silkworm.

Section /3. Oligosporogenea, Doflein.
The trophozoite produces a single pan-
eporoblast.

Genus 14. Gurleya, Doflein, 1898.
The pansporoblast produces four
spores. One species known, G. tetra-
spora, Dofl., from the hypodermic
tissue of Daphnia maxima at Munich.
Genus 15. Thelohania, Henn., 1892.
The pansporoblast produces eight
spores. Five species known, all from
the muscles of Crustacea. Genus 16.
Pleistophora, Gurley, 1893. The pan-
sporoblast produces numerous spores.
P. typicalis, Gurley, muscles of various
fishes (Fig. 114); an undescribed
species observed in a Trematode
(Leger). Many of the numerous FIG. 114.

species described under the name portion of a section through a muscle
Gluqea are referred bv Labbe to this fibre of Cottus scorpim invaded by Pleistophora

typicalis, Gurley. m.f, muscle fibrils, retam-
genus. ing their striation ; myx, cysts of the parasite,

Myxosporidia (?) incertae sedis.— lying between the fibrils.
Under the name Myxocystis ciliata,

Mrazek (1897 [110]) has described a parasite found in Limnodrilus
daparedianus. The parasites in question were only observed in a single
instance, occurring in vast numbers, and rendering the host opaque and
greyish in appearance. They were found in the wall of the gut or in
the body-cavity, as spherical or oval masses, 50 to 100 p. in diameter,
often united in groups. They showed a distinct etoplasm, usually
prolonged into a fur of delicate filaments, similar to those seen in
many Myxosporidia (e.g. Myxidium, lieberku'hnii, p. 281). The endoplasm
contained nuclei of different sizes, and also spores, the latter sometimes
filling up the entire endoplasm. Each spore was oval, 4 /u, in length,
resembling a spore of Glugea, and contained a strongly refractile body,
perhaps a polar capsule. Mrazek considers that Myxocystis shows some

-m.f.

298

THE SPOROZOA

points of resemblance to the Sarcosporidia, and that its position is at

present uncertain.

From certain freshwater Oligochaetes peculiar parasites have been

described by Stole [112], who regards these organisms as constituting a

distinct group of animals, named by him
Actinomyxidia, supposed to be inter-
mediate in position between Myxo-
sporidia and Mesozoa. Stoic's memoir
is in Bohemian, but an abstract is given
by Mrazek (Zool. Centralbl., vii., 1900,
p. 594), who considers these parasites to
be Myxosporidia allied to Ceratomyxa.
Stole distinguishes three genera, Hex-
actinomyxon, Triactinomyxon, and Synac-
tinomyxon (see Fig. 115 and description).
Phylogeny. — Thelohan, whose investi-
gations upon the Myxosporidia form the
bulk of modern scientific knowledge of
the group, considered the disporous
forms as being at once the highest and
the most primitive members of the

C.

Fio. 115.

Figures of " Actinomyxidia," after Stolfi [112]. a, Hexactinmnyxon psmnmoryctis, Stolfi (par.
Psammoryctes barbatus). b, Synactinomyxon tnbificis, Stole (par. Tubifex rivulorum). c, Triactino-
myxon ignotum, Stole (par. CUtellio sp.). d, upper portion of Hexactinomyxon showing two of
the three polar capsules, one with filament discharged.

entire order. The Disporea all live freely as amoeboid organisms in
the bile or urine ; they exhibit the greatest capacity for locomotion
by means of their highly specialised pseudopodia, and their repro-
duction is perhaps of a primitive type in that each trophozoite pro-
duces but a single pansporoblast. The genus Sphaerospora connects
them with the Polysporea, which on this view are to be considered as

THE SPOROZOA 299

forms exhibiting adaptive degeneration due to their parasitic life. The
tendency to such degeneration is to be regarded as having reached its
culminating point in the tissue-infecting Myxobolidae and Cryptocystes, and,
as in other parasites, it goes hand in hand with a great increase of the
reproductive power, shown in the large number of spores produced by
each individual.

It is hardly possible in the present state of knowledge to put forward
any criticisms upon these interesting speculations until more is known of
the relationship of the Myxosporidia to other Sporozoa. At the present
they stand very much apart and isolated, and until intermediate forms
are discovered linking them to other groups, it is not possible to decide
which forms are to be considered as the most primitive in their organisa-
tion. As regards the reproductive capacity, however, it may be pointed
out that on the whole it is distinctly related to the habitat of the parasite.
Thus the Disporea all infest regions of the body in which their spores
can pass to the exterior without difficulty by natural channels, and there
is no danger of the spores becoming stale or dying off from too long
retention within the body of the host, as so frequently happens in the
tissue -infecting forms. In the latter, therefore, a much greater repro-
ductive capacity is necessary to guard against the danger of staleness than
in the former, in which no such risk exists. Not only is it necessary for
the tissue-infecting forms to produce more spores, but also to keep up a
constant supply of them, so that there may always be ripe spores ready
to carry on the race when the opportunity for their dissemination arrives.
These considerations do not, however, in any way invalidate Thelohan's
conclusions.

ORDER 5. Sarcosporidia.

The Sarcosporidia are the least known of all the chief orders of
Sporozoa, in spite of the fact that, although restricted in occurrence,
and also, apparently, as regards variety of genera and species, they
are exceedingly abundant as individuals and very easily obtained
as material for investigation. So far as it is possible in the present,
state of knowledge to characterise the group, their distinctive
features are as follows. With the rarest exceptions, they are
parasites of the striped muscles of warm-blooded vertebrates, birds
and mammals. The trophozoite is an elongated body, which, in
the earliest stages hitherto observed, is motionless, and is limited
at first by a delicate cuticle, later by a thick envelope of compli-
cated structure. Spore-formation commences at an early stage
and proceeds during the growth of the trophozoite (hence Neo-
sporidia), which may attain to a great size. The spores, which
are produced in great numbers, are minute sickle -shaped or
spindle-shaped bodies, with a very delicate envelope containing (1)
the sporoplasm, with a single nucleus ; (2) an oval striated body,
placed at the pole of the spore, and representing, apparently, a
polar capsule such as is found in the Myxosporidia. In some

300

THE SPOROZOA

individuals, however, only naked gymnospores appear to be
produced, probably serving for multiplication of the parasite
within the host.

(a) Occurrence, Habitat, etc. — The Sarcosporidia have so far been
found, with few exceptions,1 only in warm-blooded vertebrates.
In mammals they occur very frequently in domestic animals, and
are nearly always to be found in the pig and the sheep. They
also occur commonly in the horse and ox, and have been found in
a number of other mammals, including the human species.2 In
birds they have been found in domesticated species, such as the
common fowl and duck, and in wild birds, as, for example, the
blackbird.

The earliest stage of the parasite which has been observed is
lodged within the substance of a muscle-fibre in the form of an
elongated body known as a "Miescher's Tube" (Fig. 117). The
muscles affected are more especially those of the trunk in the
vicinity of the stomach ; the muscles of the oesophagus are the
chief seat of the parasite (Fig. 116),
then those of the larynx, the body-
wall, and the diaphragm, and the
psoas muscles. In acute cases all the
skeletal muscles may be infected,
even those of the head. Sometimes
the parasites are found in the eye-
muscles. Within the muscle - fibre

FIG. 116.

Sarcosporidia in the ox ; a transverse
section of the oesophagus, natural size,
showing the parasites in the outer (a, 6,
c, d, e)and inner (/, g, /i)muscular coats.
(From Wasielewski, after Van Becke.)

FIG. 117.

Longitudinal section of a
muscle-fibre containing a Sarco-
sporidian parasite, X60. (From
Wasielewski, after Van Eecke.)

the parasite grows until it distends the fibre to five or even ten
times its normal breadth, absorbing the contractile substance as it
does so. Finally, it is surrounded only by the sarcolemma and

1 The exceptions are Sarcocystis platydactyli, described by Bertram from the
muscles of the gecko, Platydactylus mauritanicus, and a species observed by Liihe in
the lizard Lacerta muralis.

2 For the recorded cases of Sarcosporidiosis in man, see Smith [121], p. 1, and
Vuillemin [122], p. 1152.

THE SPOROZOA 301

sarcoplasm, the latter having greatly increased in amount, its
nuclei multiplying by direct division (Laveran and Mesnil [119]).
The parasite then passes from the substance of the muscle into
the adjacent connective tissue, still surrounded, however, by a
secondary coat derived from the muscle-fibre, in which the nuclei
disappear. Thus the parasite is found under two phases, which
have been given distinctive names under the impression that they
represent distinct genera, the first lodged in the muscles (Miescheria),
the second in the connective tissue (Battnania).

In the second phase the parasite rounds itself off more, and
the tissues of the host form an adventitious cyst round it. The
cysts are conspicuous objects, often reaching a length of 16 mm.
in the sheep, while in the roebuck (Cerims capreolus) cysts of
50 mm. in length have been observed. Within the cyst are formed
vast numbers of minute germs (Fig. 120), either true spores or the
so-called " Rainey's corpuscles " (see below). The cysts are observed
to degenerate in some cases, their adventitious walls becoming
calcified, as the result of a defensive process on the part of the
host. Probably these are cysts containing spores, which can only
develop in another host. In other cases, the cysts burst and
spread their contents in the surrounding tissues, destroying the
muscles and producing tumours and abcesses within which the
parasite is found in the condition of "diffuse infiltration," like
many Myxosporidian parasites. It is in this stage that the con-
sequences may be dangerous or fatal to the host. The symptoms of
Sarcosporidiosis in the pig are " paralysis of the hinder extremities,
a skin-eruption, and general symptoms of sickness, such as thirst,
increased body -temperature, and dim, streaming eyes."1 The
disease is sometimes the cause of fatal epidemics amongst domestic
animals, especially sheep. In the mouse also Sarcocystis muris is
a very deadly parasite. Mice attacked by it are distinguished
by their puffy, bloated appearance (Koch [118]), and are soon killed
by it.

Many observations tend to show that the dangerous effects of
the Sarcosporidian parasites are not caused merely by the dis-
turbances which they set up in the tissues of the host, but are
due to an active poison secreted by the parasite itself. The
indefatigable French naturalists, Laveran and Mesnil [120],
have succeeded in isolating the toxin of the Sarcosporidian
parasite of the sheep, and have named it sarcocystin. This
substance is found to be extremely toxic to the experimental
rabbit, since a demimilligramme of the fresh extract, containing
T\5- milligramme of solid matter, kills one kilogramme of rabbit,

1 Quoted from Wasielewski [7], from whom many other facts stated here are
taken. The skin-eruption has an interesting parallel in the Myxosporidian disease
of the barbel (see p. 278).

302

THE SPOROZOA

with symptoms like cholera, in a very short time; in a feebler
dose it produces a cachexy which usually ends fatally. In other
animals the action of sarcocystin is more feeble and transitory in
its effects.

As regards the origin of Sarcosporidiosis, or the manner in
which it spreads, nothing can be said definitely at present, but
it is possible to put forward a few more or less probable surmises,
which will be found below (p. 308).

(b) Morphology and Evolution. — The youngest examples of the
trophozoite that have been observed
had already attained a length of
40 [i with a breadth of 6 ^ (Fig.
118, a). They are found as whitish

7

FIG. 118.

Stages in the growth of Sarcocystis tenella of the
sheep, a, youngest observed stage in which the
radially striated outer coat lias not appeared ; the
body of the trophozoite is already divided into a
number of cells or pansporoblasts (fc). 6 and c,
older stages with numerous pansporoblasts and
two envelopes, an inner membrane and an outer
radially striated layer. (From Wasielewski, after
Bertram.) c

opaque bodies limited by a fine, structureless cuticle. The
protoplasm of the trophozoite is already in part segmented up
to form a number of nucleated corpuscles or cells, which are
evidently homologous with the primitive spheres or pansporo-
blasts of the Myxosporidia, and may therefore receive the same
name.

In the next stage the parasite, still intramuscular in position,
has increased in size and is surrounded by two coats (Fig. 118, b).
The outer coat, which is thick and shows a fine radial striation,

THE SPOROZOA

303

has received divers interpretations. While some observers regard
the striation as due to the presence of fine pores or canalicules
traversing a clear envelope, others, amongst whom are the most
recent investigators, Laveran and Mesnil [119], declare the striation
to be caused by a thick fur of fine filaments, planted vertically
to the surface of the trophozoite, and serving to attach it to the
fibrillae of the muscle -fibres. Both these views perhaps contain
something of the truth ; the external envelope probably arises

FIG. 119.

Sarcocystis miescheriana (Kiihn) from
the pig ; late stage in which the body lias
become divided up into numerous cham-
bers or alveoli, each containing a number
of germs. (From Wasielewski, after Manx.)

Fio. 120.

Sarcocystis of the ox ; section of
a stage similar to Fig. 119. a, sub-
stance of muscle-fibre ; b, envelope
of parasite ; c, nuclei of the muscle ;

d, parasitic germs (gymnospores) ;

e, walls of the alveoli. In the peri-
pheral alveoli are seen immature
germs. (From Wasielewski, after
Van Eecke.)

from a stiff, radially striated ectoplasmic layer, such as is met
with amongst some Myxosporidia,1 which, by breaking down of
the substance between the striations, is converted into a furry
envelope. The inner coat is formed of a thin homogeneous
membrane, prolonged externally into the filaments, and internally
into the system of chambers previously described. Internally to
the two coats lies the protoplasmic body of the trophozoite, com-
parable to the endoplasm of the Myxosporidia, and consisting

1 Compare especially Myxidium lieberk'dhnii above, p. 281, Fig. 88.

304 THE SPOROZOA

almost entirely of numerous pansporoblasts (Fig. 1 1 8, b and c), which
are continually being formed at the two poles of the trophozoite.
Between the pansporoblasts, septa or partitions extend in from
the inner coat, isolating them from one another, so that the entire
endoplasm has a chambered or alveolar structure, each chamber
containing originally a single pansporoblast (Fig. 119). Towards
the centre of the body each pansporoblast has developed into a mass
of spores or other germs, completely filling a chamber (Fig. 120);
towards the poles pansporoblasts or early stages in spore-formation
are found, and the two extremities of the body are occupied by
the two regions of proliferation, so that the parasite grows by
forming new spores at its two ends.1

In the third stage the parasite is encysted in the connective
tissue, as above described. The body -form is less elongated,
having become more or less rounded off, and the two polar areas
of proliferation now extend round the whole trophozoite, forming
a peripheral zone, the external layer of the body of the parasite,
consisting of small alveoli, containing elements in process of
development. Internally to the zone of proliferation are found
alveoli crammed with ripe spores, which constitute an inter-
mediate zone. The centre of the body is occupied by a granular
substance, derived from disintegration of the centrally placed
spores, which having become stale and past their prime, die and
break up. The parasite continues to grow within the cyst, new
spores being formed towards the periphery, to replace those which
die off towards the centre. The development of the spores has
not been followed in detail, but the pansporoblasts have at first
one nucleus, later several.

The germs or reproductive bodies which arise from the pan-
sporoblasts within the alveoli appear to be of at least two kinds,
which may be conveniently distinguished as chlamydospores and
gymnospores respectively.

The chlamydospores, commonly termed " spores " simply, are
minute rod -like bodies, which vary in details of form and size
in different species. In Sarcocystis tenella of the sheep (Fig. 122)
they measure about 14 /x in length by 3 /x in breadth. One
extremity is more rounded, the other pointed. The spore-
membrane is very thin, and the chlamydospores themselves very
delicate and fragile ; they are easily acted upon by reagents,

1 Smith [121], in his recent account of the formation of gymnospores in Sarcocystis
muris, gives a different interpretation of the various stages. He terms " sporoblasts "
the " roundish or polyedral masses " which have been homologised above with pan-
sporoblasts, and considers that the partitions between them are not ingrowths of the
internal wall, but are " simply the walls of the sporocysts in close apposition with one
another." He regards the gymnospores as sporozoites. Smith's terminology is the
outcome of a misleading comparison of the Sarcosporidia with the Coccidia. He does
not seem to have seen true spores.

THE SPOROZOA

3°5

and even in distilled water they swell up and become globu-
lar. The pointed extremity of the chlamydospore
is occupied by a clear space, about 5-6 p, in length,
in which a delicate spiral striation can be seen in
the fresh condition. The rounded end of the spore
is almost filled by a large oval nucleus, containing a
distinct nuclear corpuscle. The median portion of
the spore is occupied by protoplasm with coarse
granules. All the chlamydospores have the same
structure.

The spirally striated body situated at the pointed
end of the chlamydospore has great resemblance to
a polar capsule of a Myxosporidian spore, but it
is by no means certain how far the similarity ex-
tends. The most convincing proof of their similar
nature would be the extrusion of the filament,
which in Myxosporidia can be brought about arti-
ficially by a great number of reagents. It has
been asserted by some investigators that a filament
is extruded from the capsule of the Sarcosporidia
also, and in support of this state-
ment Van Eecke has published a
figure,1 which has had the effect of
leading competent authorities to
doubt the fact (see Laveran and
Mesnil [119], p. 247; Liihe [5],

FIG. 121.

Sarcoeystis hueti (Blanchard), from
the muscles of Otaria californica. re,
muscle-fibre containing a parasite, the
body of which is chiefly made up of a
vast number of gyinnospores. b, clumps
of gyinnospores, each clump contained
in an alveolus limited by a delicate mem-
brane, c, different stages of the navi-
culargymnospores. (From Wasielewski,
after B'albiani.)

FIG. 122.

Spores of Sarcoeystis tenella, Raill., from
the sheep. «, spore in the fresh condition,
showing a clear nucleus (») and a striated
body or capsule (c). 6, spore stained by
Heidenhain's Iron Haematoxylin method ;
the nucleus (n) shows a central karyosome ;
the striations of the polar capsule (c) are not
visible. (After Laveran and Mesnil.)

1 Reproduced by Wasielewski [7] (Fig. 107, p. 125). Eight spores are shown,
three of them with extruded filaments ; of the latter, one has a single filament at the
pointed end ; the second two filaments at the pointed end ; and the third a filament
at each end. In the discussion following the reading of Koch's memoir [118], Wasie-
lewsky has recently affirmed positively the extrusion of a polar filament from the spore.

3o6 THE SPOROZOA

p. 89). The allegation stands therefore in need of further
support; the most recent investigators, Laveran and Mesnil [119],
were unable to bring about extrusion of a filament from the
spore. But although complete identity of structure has not been
established, it is nevertheless extremely probable that the spirally
striated body of the Sarcosporidian chlamydospore
%~^? is strictly homologous (i.e. homogenetic) with the

Myxosporidian polar capsule, and is an additional
o^ proof of the relationship between the two groups.

The gymnospores, commonly described under
an the names of " sporozoites " or "Rainey's cor-

ps' puscles," vary a good deal in size and appearance

f& (Figs. 120, 121, 123). Their form has been com-

ty? pared in different instances to that of a bean,

FIG 123 kidney, crescent, sickle, or banana. In Sarcocystis

Gymnospores of muris they are about 12 //, by 4 p. in dimensions,
a?i£fSfthe pi'^show" ^ut in otner species they may be larger than this,
ing their changes of or much smaller (3 or 4 u. x 1 u). Each consists

form. (From Wasie- r/^i ill i j. • •

lewski, after Manz.) of finely -granulated protoplasm, containing a
nucleus, a few coarser granules, and sometimes
one or two vacuoles. Those of Sarcocystis muris show active
movements when warmed up to 35°-37° C. They perform gliding
movements on a circumference corresponding to their own curva-
ture, occasionally revolving also on their long axis, and thus
producing "a boring or screw -like action" (Smith). In other
cases they are said to become amoeboid under similar conditions.
Both kinds of movement are probably to enable them to penetrate
the tissues of the host.1

With regard to the significance of the two kinds of germs, and their
destiny and further development, very little can be asserted definitely at
present. The whole question of the reproductive bodies of the Sarco-
sporidia is?i indeed, in a very confused state, and to generalise with regard
to them is difficult, since no single observer seems to find more than one
kind of spore. Those who, like Laveran and Mesnil, describe spores, say
nothing about any gymnospores ; and those who, like Smith and Koch,
describe gymnospores, do not appear to be aware of the existence of any
other kind of spore. It might be inferred from tins that some species,
such as Sarcocystis tenella, produce only chlamydospores, and others, such
as S. muris, only gymnospores, but it is far more likely that both kinds
are produced by the same parasite, sometimes the one, sometimes the
other occurring, as the result of conditions as yet unknown. It is note-
worthy in this connection, that S. muris, in which only gymnospores have

1 Besides the two kinds of germs described above, cysts have been described con-
taining spermatozoon -like structures (see Wasielewski [7], p. 125), but from the
accounts given it is difficult to form any clear idea of the nature of these bodies,
or of their significance in the economy of the parasite.

THE SPOROZOA 307

been described, is of all species apparently the most deadly to its host,
multiplying in it and overrunning the entire muscular system with
fatal rapidity.

It is certain that the parasites possess the power of multiplying to
a dangerous extent in the tissues of their host, and it is still more
certain that they are able to infect fresh hosts. From all that is known
in other Sporozoa, it is reasonable to identify the naked gymnospores as
the agents in the endogenous dissemination of the parasite, comparable
functionally to the merozoites of Coccidium, and to regard the chlamydo-
spores as destined for the infection of fresh hosts. Experimental proof of
these hypotheses is as yet lacking, however. The only direct evidence
bearing upon the dissemination of these parasites is that brought forward
by Smith [121], who found that mice may contract the infection of Sarco-
cystis muris if fed with the flesh of a mouse infested with the parasite. It is
extremely improbable, however, that this is the natural mode of infection.
It would be difficult, as Smith points out, to account for the Sarcosporidia
of cattle in this way. A parallel case of infection due to cannibalism has
been described by Schaudinn for Coccidium (see p. 221). The chief point
of importance established by the experiments of Smith is the fact that
infection takes place by way of the digestive tract, as in the vast majority
of Sporozoa. In this way the close proximity of the cysts, as a rule, to
the oesophagus and stomach receives a simple explanation.

In Smith's experiments the gymnospores seem to have been the agents
of infection, since he observed no other kind of germ, but it is probable
that, in the natural method of cross-infection, it is the chlamydospores
that are concerned. This conclusion receives further support from the
facts stated above with regard to the death and disintegration of stale
spores and their continual replacement by others freshly formed ; a state
of things to which a parallel exists in the Myxobolidae and other tissue-
infecting Myxosporidia (p. 289), and also in coelomic Gregarines. It
may be reasonably inferred that in Sarcosporidia also the chlamydo-
spores are not able to develop further in the host in which they are
produced, but are in readiness for the moment when they can be trans-
ferred to another animal, failing which event, they become stale and
perish. We have no clue, however, to the manner in which the cross-
infection by the chlamydospores is effected, and nothing but surmises can
be put forward.

The most remarkable feature of the chlamydospores is their extremely
fragile nature. Unlike the very tough and hardy spores of other Sporozoa,
those of Sarcosporidia betray a delicacy of constitution which must render
them very unfitted to brave the elements outside the body of the host.
For this reason many authorities l have expressed the belief that some
intermediate host is required, as in the case of the malarial parasite; to
convey the infection from one host to another. While this is an extremely
probable hypothesis, no facts in support of it have been as yet discovered.
But from the position of the parasite deep in the muscles of the host, it
can hardly be a blood -sucking insect, as in the case of malaria, which

1 Wasielewski [7], p. 126 ; Laveran and Mesnil [119], p. 248.

308 THE SPOROZOA

spreads the infection. Three possibilities, at least, suggest themselves in
this connection : —

(1) That the intermediate host is a large carnivore of some kind, e.g.
the dog, for the parasites of the pig or sheep.

(2) That, after death of the host, the parasites are taken up by some
carrion - feeding animal, which might be either (a) a vertebrate, bird or
mammal ; or (6) an invertebrate, such as the blow-fly or the burying beetle.

(3) That the infection might be taken on by some internal parasite of
the vertebrate host, e.g. a flat-worm or nematode.

The third supposition is extremely unlikely. The second receives,
perhaps, some support from the extremely toxic nature of the parasites
themselves, which would be a property acting in their interests, by
producing the death of the host. In any case there would still remain
the question as to how the parasites reinfect the vertebrate host. It
appears to be generally young animals that become infected, since the
smallest trophozoite that has been described hitherto was found in a lamb
eight months old, and it is extremely probable that the infection is by
way of the digestive tract. Possibly, therefore, in the intermediate host
the parasites form spores more resistent than those formed in the verte-
brate host. A remarkable feature of the artificial infections effected by
Smith was the long incubation period — 40 to 50 days — which elapsed
between the actual infection by feeding and the appearance of the parasite
in the muscles. Evidently there is much still to be made out about these
interesting parasites, and the field is one ripe for investigation.

(c) Classification. — Since Blanchard's genera Miescheria and
Balbiania denote merely stages in the life-history of the parasites,
they have become nomina nuda, and all Sarcosporidia are placed at
present in a single genus : —

Sarcocystis, Eay Lankester, 1882, with the characters of the order. A
great number of forms have been seen in different animals, many of which
are probably distinct species, but only a few have received specific designa-
tions : such are S. miescheriana (Kiihn), from the pig ; S. tenella, Raillet,
from the sheep ; S. platydactyli, Bertram, from the gecko ; S. muris,
Blanchard, from the mouse, etc.

(d) Affinities. — The nearest relationship of the Sarcosporidia is
undoubtedly with the Myxosporidia, and with the sub-order Cryp-
tocystes (Microsporidia, Glugeidae) in particular. The affinity is
manifested in three points more especially — (1) the spore-formation
proceeds continuously during the whole trophic stage ; (2) they
are cell-parasites ; (3) the spores have a single polar capsule. The
Sarcosporidia seem to be, in fact, the representatives of the Myxo-
sporidia in warm-blooded hosts, and it is not improbable that in
the future the two groups will be more closely united in systematic
classifications.

THE SPOROZOA 309

SPOROZOA INCERTAE SEDIS.

In addition to the five well-characterised orders of Sporozoa de-
scribed in the foregoing pages, a certain number of forms have been
discovered and described by various naturalists, which cannot be
definitely inscribed in any of the above orders. To a large extent
the uncertain position of these forms is due to the gaps existing
in our knowledge of them. Just as certain genera, ranked in older
treatises amongst those of doubtful affinities, have been referred,
as the result of more extended studies, to a definite position in the
classification of the Sporozoa — as, for instance, Karyopliagus (p. 208)
and Piroplasma (p. 269) — so it is probable that a more accurate
knowledge of many forms now difficult to classify will bring to
light unmistakable relationships between them and better known
types. Other forms, again, will perhaps turn out not to be true
Sporozoa at all. And finally, when these two classes of organisms
have been sifted out, there will perhaps remain a certain number
of types which must be ranked as orders truly distinct from any
of those described above. Provisionally, three orders may be
recognised, besides a certain number of very doubtful types.

ORDER 6. Haplosporidia, Caullery and Mesnil.1

The forms comprised in this order agree in having a very simple
developmental cycle, which in its principal features is as follows : — The
youngest stage of the parasite is a minute rounded corpuscle with a
single nucleus. With further growth the number of nuclei increase
continually.2 When full-grown the multinucleate body becomes divided
up to form a mulberry-like mass, or "morula," of ovoid or spherical
spores, each with a single nucleus, and with no trace of any sort of
internal differentiation. From each spore arises one of the corpuscles,
which was taken as the starting-point of the life-cycle. The following
genera are referred to this order : —

Genus 1. Bertramia, C. and M., 1897, for B. capitellae, C. and M.,
from the body-cavity of Capitella capitata, and for the peculiar parasites
occurring in the body-cavities of Rotifers,3 first described by Bertram
[116] in 1892 ; seen, fide Cohn [130], by Fritsch in 1895, and named
by him Glugea asperospora ; named by Zacliarias, in 1898, Ascosporidium

1 The name of this order was written Aplosporidia by Caullery and Mesnil [128,
129], but was corrected to Haplosporidia by Ltihe [5], since the word is evidently
derived from air\ovs, simple, and not from dirXoir, unseaworthy.

2 Caullery and Mesnil term the multinucleate trophozoite the plasmodium, but
in the typical members of the order it has a definite body -form, and is not in any
way amoeboid.

3 These parasites were seen and studied by the present writer when working in
Professor Biitschli's laboratory in Heidelberg in 1888. Extraneous circumstances
prevented the completion of the studies upon them, and most unfortunately the
drawings made of them were lost, but some permanent preparations were kept, from
which the figures given above are drawn.

3io

THE SPOROZOA

blochmanni ; and recently studied by Cohn, I.e., under the name Bertramia
asperospora (Fritsch). The trophozoites in this genus commence growth
as small rounded, uninucleate cells (Fig. 124, </, h), which become elongated,
sausage-shaped, or cylindrical bodies in B. asperospora (Fig. 124, a-c), or
flattened elliptical discs in B. capitellae, but in either case have a number
of nuclei, which multiply as growth proceeds (Fig. 124, i, j). In B.

Fio. 124.

Bertramia asperospora (Fritsch), from the body-cavity of Brachionus. a, young form with
opaque, evenly-granulated protoplasm and few refringent granules ; the nuclei, which are
difficult to make out clearly in the actual specimens, are small, and appear to be surrounded
each by a clear space, b and c, full-grown specimens, with large nuclei and clearer proto-
plasm, containing numerous refringent granules (r, gr). d and e, morula stages, derived from
ft and c by division of the body into segments centred round the nuclei, each cell so formed
being a spore. Between the spores a certain amount of intercellular substance or residual
protoplasm is left, in which the refringent granules seem to be imbedded. The morula may
break up forthwith and scatter the spores, or may first round itself off and form a spherical
cyst with a tough, fairly thick wall. /, empty, slightly shrunken cyst, from which the spores have
escaped g, free spore, or youngest unicellular trophozoite. h, i, j, commencing growth of the
trophozoite, with multiplication of the nuclei, which results ultimately in forms such as a and
6. Original figures, copied from drawings made with the camera lucida, x 1040. a-c, from
one preparation, and from the same Rotifer, d-j, from another.

capitellae the number of nuclei present in the full-grown parasite is from
40 to 80, but in B. asperospora it is less, from 25 to 35, as a rule ; and
the latter species is also characterised by the possession of large refringent
granules in its protoplasm, which is limited by a distinct but delicate
cuticle. When growth is completed, the body becomes segmented to form
a mulberry-like mass of spores, each centred round one of the nuclei
(Fig. 124, d, e).

In B. asperospora the body-form of the morula is not different at first

THE SPOROZOA 311

from that of the multinuclear trophozoite, except that its smooth contours
are exchanged for a lobulated outline (Fig. 124). According to Bertram's
observations, the sausage -shaped morula may now break up into its
component cells or spores, which become scattered in the body-cavity of
its host. The parasites observed by the present writer, however, were
seen to round themselves off and assume a spherical form, a tough cyst-
rnembrane then being formed round the whole mass (Fig, 124,/). Bertram
also observed cysts in a single case. As the parasites are quickly fatal to
their host, it is highly probable that rapid endogenous multiplication is
effected by breaking up of the sausage-shaped morula and liberation of
the spores without encystment, and that in other cases a protective cyst
is formed. There appeal's to be no difference whatever, however, in the
spores in either case, each spore being a small rounded uninucleate cell,
limited by a delicate membrane. The spores are set free by the death
and disintegration of the host, and are then swallowed by other Rotifers.
In some way which has not been observed the spores pass from the gut
into the body- cavity, and each becomes the starting-point of a fresh
generation of the parasite. All stages of the parasite hitherto seen are
perfectly motionless.

In B. capitellae the morula becomes encysted, and the contents of the
cyst are divided up into compartments by trabeculae extending from the
cyst-wall, formed apparently from residual protoplasm not used up to
form spores. The alveolar condition of the cyst may be compared with
that seen in Sarcosporidia.

Genus 2. Haplo [Aplo-]sporidium, Caullery et Mesnil, 1899, for H.
heterocirri, C. and M., parasite of the body -cavity of Heterocirrus viridis ;
and H. scolopli, C. and M., parasite of the intestinal epithelium and
perivisceral sinuses of Scoloplos miilleri. As in the last genus, a small
uninucleate corpuscle becomes by growth and multiplication of nuclei the
full-grown, multinucleate, but still unicellular trophozoite, measuring
100-150 fj. in length by 20-30 p in breadth. The body then becomes
segmented into a " morula " of uninucleate cells. In H. scolopli each
cell of the morula gives rise by further division to four uninucleate spores,
but in H. heterocirri each segment of the morula becomes a single spore.
In both cases the spores are distinguished from those of the preceding
genus by the possession of a cap or operculum at one pole of the tough
envelope, so that the spore resembles to a certain extent a poppy-
capsule. In sea-water the operculum opens and sets free the contained
sporoplasm.

Genus 3. Coelosporidium, Mesnil and March oux, 1897, for C. chydori-
cola, M. and M., from the body-cavity of Chydorus sphaericus. A uni-
nucleate corpuscle grows into a multinucleate, sausage -shaped body,
60-100 ft in length by 15-20 p. in breadth, enveloped in a thick mem-
brane, and containing centrally - placed fatty globules and refringent
granules. Later the protoplasm becomes divided into segments corre-
sponding with the nuclei, and forms eventually a cyst containing numerous
spindle-shaped uninucleate spores. In addition, the spore-formation there
appears to be an endogenous cycle, in which the protoplasm contains no
refringent globules. The parasite castrates its host.

312 THE SPOROZOA

ORDER 7. Serosporidia,1 L. Pfeiffer.

This order was instituted by its founder for minute parasites observed
by him in the body-cavity (haemocoele) of certain Crustacea. The follow-
ing genera are referred here : —

Genus 1. Serosporidium, L. Pfeiffer, 1895. The type -genus of the
order contains several species of oval or rounded parasites which repro-
duce in two ways — (1) By simple division ; (2) by forming a cyst within
which the parasite breaks up into numerous amoeboid germs. S. cypridis,
L. Pffr., from the body-cavity of Cypris sp., and other species from Cypris
virens and Gammarus pulex.

Genus 2. Blanchardina, Labbe", 1899 (nom. nov. pro Blanchardia,
Wierzejski, 1890). Amoeboid masses, which become cylindrical or sac-
like, and then of beaded form. Each bead becomes separated and forms
a cyst, at first fusiform, later oval or spherical Further reproduction
not observed. Unique species B. cypricola, Wrzski., from body-cavity of
Candona Candida and Notodromas monacha.

Genus 3. Botellus, Moniez, 1887. Elongated ovoid tubes, containing
halter-shaped spores, each with two nuclei. B. typicus, Moniez, from
generative organs and haemocoele of Ceriodaphnia reticulata, Chydorus
sphaericus, and Moina rectirostris. Two other species from Cypris and
Daphnia.

Genus 4. Lymphosporidium, Calkins, 1900, for L. truttae, Calkins,
parasite of the brook trout, Salvelinus fontinalis. The trophic phase
of the parasite commences in the lymph as a minute germ which grows
into an amoeboid body. The amoebula then invades the muscle-bundles
of the intestine and other organs. In this situation the amoebula grows
into the adult organism, which has its protoplasm full of chromatin
granules, forming a distributed nucleus. Spore-formation commences by
the parasite rounding itself off and being set free in the lymph or other
cavities (gall-bladder, intestine), and by a concentration of the chromatin
into several masses in the interior of the cell, each such mass becoming a
spore. The spores are carried to all parts of the body in great numbers,
blocking the lymph-passages, and causing sores and ulcers, and finally
bringing about the death of the host. When set free the spores infect
fresh hosts, probably by way of the digestive tract. In this situation
they develop further, each producing eight germs or sporozoites, which
become the starting-points of fresh generations of the parasites. The
spores may, however, develop in the internal cavities of the host in which
they were produced. This parasite causes extremely virulent epidemics.

ORDER 8. Exosporidia, Perrier.

The order Exosporidia was founded by Perrier to include the peculiar
organism, ectoparasitic upon certain aquatic Arthropoda, to which Cien-
kowsky gave the generic name of Amoebidium. Many authorities con-

1 The name was written Serumsporidia by Pfeiffer, and corrected to the more
euphonious spelling, here adopted, by Wasielewski.

THE SPOROZOA 313

sider that the true systematic position of the forms is amongst the algae,
and their place amongst the Sporozoa is far from being assured. Within
the last decade, however, some other genera have been described which
are possibly related both to Amoebidium and to the true Sporozoa, and
the order may be retained provisionally for a collection of genera to which
it is difficult to assign a more definite position. The genera placed here
are best described separately.

Genus 1. Amoebidium, Cienkowsky, 1861. The forms composing this
genus differ in their habit of life from all typical Sporozoa and from any
species mentioned in the preceding pages, being ectoparasitic upon various
Crustacea or aquatic insect-larvae in freshwater. They were first discovered
by Lieberkiihn in 1856, who pointed out their affinities with "psoro-
sperms." Five years later they were the objects of detailed investigation
on the part of Cienkowsky, in whose opinion they were organisms of
vegetable nature. Other species were added to the genus by later
observers.1 A. parasiticum, Cienk., the type-species (Fig. 125), occurs on
the branchial lamellae, antennae, carapace, etc., of Asellus aquaticus,
Gammarus pulex, and various freshwater Entomostraca, and upon
Phryganea and other aquatic insect-larvae, in the form of slender tubes
(Fig. 125, a-e). At one extremity the organism is attached to the skin of
the host by a disc-like expansion, and immediately above this region the
body is slightly narrowed to form a short stalk, continued by the rest of
the tube, which is generally cylindrical and of even calibre, but may be
clubbed or exhibit other variations as regards external form. The wall
of the tube is a delicate membrane, which does not give the reactions
characteristic of cellulose. The contents of the tube consist of protoplasm,
containing fine granules, fatty spherules, and often vacuoles. The youngest
tubes contain a single nucleus, but in older individuals the nuclei multiply
as growth proceeds, and in full-grown tubes numerous nuclei are found
scattered at regular intervals along the whole length of the tube (Fig. 125,
a). The reproduction of Amoebidium is effected by two distinct methods,
which may, however, be combined in various ways. In the first place,
the contents of the multinucleate tube may be divided up by oblique
partitions passing between the nuclei, into as many uninucleate segments
or daughter -tubes as there were nuclei originally (Fig. 125, c). Each
daughter-tube (Fig. 125, 6) may then grow into a multinucleate Amoebidium
again. In the second place, the whole contents of the multinucleate tubular
body, or of the uninucleate daughter - tubes either before or after they
have left the mother-tube, may become segmented along cleavage planes
running in various directions, into a number of uninucleate amoeboid
spores (Fig. 125, d, e), which soon begin to move about within the tube,
and finally escape from it at one point or another. The amoebulae or
"zoospores" (Fig. 125, f-h) thus liberated creep about for a time, but do
not appear to feed, and have no contractile vacuole. After a time, each
amoebula comes to rest, assuming first a spherical form, with one or two
large vacuoles internally, then it becomes oval and forms a cyst (Fig. 125, i-k).
In the warmer season of the year cysts are formed with a thin wall, within

1 For references to the literature of the genus, see Biitschli [1], pp, 611-614, and
Labbe [4], pp. 122, 123.

314

THE SPOROZOA

which the protoplasmic contents divide up in a few days to form a
number of cylindrical germs, resembling sporozoites (Fig. 125, k, I). In
the winter cysts are formed with a tough envelope, the contents of which
remain dormant until the spring and then emerge. The contents of each

FIG. 125.

Amoebidium parasiticum, Cienk. , phases of the developmental cycle, a, full-grown tube with
numerous nuclei (n) ; 6, young tube with a single nucleus ; c, a tube divided up by oblique
partitions into daughter- tubes ; d, a tube divided up by transverse and longitudinal cleavages
into araoebulae, one of which (am) is seen emerging from the tube ; e, a tube containing freely
moving amoebulae ; /, g, h, free amoebulae ; i, an amoebula come to rest and of spherical
form, with a large vacuble ; j, the form has become oval and the spore-membrane is beginning
to appear at the surface ; k, I, summer-spores, with sporozoites ; m, a winter-spore, with thick
cyst-wall ; n, the contents of the winter-spore escaping ; o, the contents of a winter-spore,
which, after escaping from the cyst, have developed into a thin-walled spore containing sporo-
zoites, similar to a summer-spore ; p, q, young Amoebidia produced from sporozoites. (After
Cienkowsky ; /, g, and h are magnified 380 diameters, the other figures 285.)

such cyst, after liberation, may either become a young Amoebidium at
once or may divide into two small Amoebidia, or may undergo the same
development as the thin-walled summer-cysts (Fig. 125, m-q). Each of
the sporozoites, as they may be termed, formed within the cyst becomes
a young Amoebidium when liberated.

THE SPOROZOA

3'5

Genus 2. Siedleckia, Caullery and Mesnil, 1898, for S. nematoides,
C. and M., parasitic in the digestive tract of Scoloplos miilleri and Aricia
latreillei. It occurs as a minute, worm-like creature (Fig. 126), attached by
one extremity, termed proximal, to a cell of the intestinal epithelium.
The body hangs free in the lumen of the gut, and performs various
movements of torsion and flexion. Sometimes individuals are found
unattached and progressing freely. The youngest stages are spindle-
shaped and slightly curved, resembling sporozoites, with one or two nuclei
(Fig. 126, a). As they grow in length the nuclei increase in number,
keeping at first in single file (Fig. 126, b-d), but later forming several rows
at the distal extremity of the body (Fig. 126, e). The full-sized parasite is

d,

Fio. 126.

Phases of the life-cycle of Siedleckia nematoides, Caull. and Mesn. (par. Scoloplos miilleri, etc.).
a, young stage, with two nuclei ; b, c, d, older stages, with nuclei (n) still in .single file ; in d
some of the nuclei are commencing to elongate in a transverse direction ; e, full-grown in-
dividual, with very numerous nuclei ; /, inultinucleate spheres cut off from the distal extremity
of a parasite such as shown at e ; in g the sphere is commencing to grow into a vermiform
Siedleckia. (After Caullery and Mesnil.)

about 150 p in length and continues to elongate, but as it does so, small
spherical segments, containing a variable number of nuclei, are constricted
off from the distal extremity and detached (Fig. 126, /, g). Each of these
becomes a young Siedleckia. No other method of reproduction has been
observed.1 The facts upon which to form a judgment with regard to the
affinities of Siedleckia are therefore somewhat scanty. Labbe [130c] con-
siders it allied to the Mesozoa, but it is difficult to see why. The general
habitus of the animal is more like a Gregarine than anything else, and
Caullery and Mesnil [86] have noted its resemblance to the vermiform
Gregarines, such as Selenidium, occurring in Annelids. The general
description of Siedleckia and its reproduction reads (at least, to one who
has not seen either of these forms) remarkably like the description of the

1 It is by no means apparent bow the multinucleate spheres detached as describe
become the young forms with two or three nuclei, or whence the latter originate.

3i6 THE SPOROZOA

sch'izogony of Schizocystis given by Leger (see above, p. 191), and it is
very possible that the true position of Siedleckia may be found eventually
to be in or near the Schizogregarinae. To what extent it is at the same
time allied to Amoebidium must remain an open question.

Genus 3. Toxosporidium, Caullery and Mesnil, 1900, for T. sabellidamm,
C. and M., parasite of various Sabellidae (Fabricia sabella, Oria armandi,
Amphiglena mediterranea, Jasmineira elegans, and Myxicola dinar densis).
This form may conveniently be considered in connection with Siedleckia,
although its affinities are extremely doubtful. Its discoverers approximate
it provisionally to the coelomic Gregarines. It occurs in the form of
motionless crescents lodged principally in the phagocytic cells of the body-
cavity of the host. Each crescent has a nucleus containing two large
crescent-shaped karyosomes. In the same hosts the intestinal epithelium
contains "groups of spherules, which are perhaps the phase of endogenous
multiplication of these parasites," the spherules being supposed to fall into
the peri-intestinal blood-sinus and develop into the crescents. No other
stages are known.

Genus 4. Joyeuxella, Brasil, 1902, for /. toxoides, Bras., parasite of the
intestinal epithelium of Lagis koreni. The youngest stage of the parasite
is a crescent-shaped intracellular body containing a nucleus with a large
karyosome, and near the nucleus a small body resembling a micronucleus,
and sometimes also another one further off. With further growth the
nucleus multiplies, and the full-grown crescents have very numerous small
nuclei. The body then divides up into numerous small elements. The
further development has not been followed, but the epithelium of the
same hosts also contains bodies resembling cysts of microgametes. Brasil
considers that this form has some points of resemblance to Gonospora,
Selenidium, and Toxosporidium ; to Siedleckia, from which it differs in
form, immobility, and intracellular habitat ; but that on the whole it
shows more affinities with Coccidia than with Gregarines.

Genus 5. Exosporidium, Sand, 1898, for E. marinum, Sand, an
ectoparasite observed, in a single instance, on the leg of a marine Acarus
at Eoscoff. The parasite has a general resemblance to Amoebidium, being
attached by one extremity of the cylindrical body, which becomes slightly
narrower towards the free distal extremity. The dimensions given are
193 //. in length by 23 fj. in breadth at the fixed extremity, 17 ft at the
free end. The body is limited by a distinct membrane, within which the
protoplasm is divisible into (1) an ectoplasmic layer resembling that of
Gregarines, clear and free from coarse granulations ; (2) a granular endo-
plasm containing six nuclei disposed in a longitudinal series. Two kinds
of movements were observed — flexions, followed by sudden straightenings,
of the whole body, and slow torsions of the free extremity. Sand con-
siders this organism to be a Sporozoon, allied to Amoebidium.

The following genera are of quite uncertain position amongst the
Sporozoa, if indeed they are Sporozoa at all : —

Metchnikovella, Caullery and Mesnil, 1897, for certain minute para-
sites infesting the endoplasm of certain Gregarines. The first phase of
the parasite is a number of small nucleated corpuscles lodged in a vacuole

THE SPOROZOA 317

of the endoplasm ; the corpuscles multiply by fission, forming Strepto-
coccus-like bands, which spread through the host ; finally, fusiform cysts
are formed, arranged with their long axis parallel to that of the Gregarine,
and containing a number of nucleated corpuscles. The fusiform bodies
probably represent the resistent phase which serves to infect fresh hosts.
The type is M. spionis, C. and M., from Gregarina (Polyrhabdina, Ming. =
Selenidium, Giard T) spionis, Kolliker, parasite of Spio martinensis. Other
species are known from the Gregarines of other Annelids.

Hyalosaccus, Keppene, 1899, for H. ceratii, Kepp., a parasite of
various Dinoflagellata. As it is described by its discoverer in the Kussian
language, the reader anxious for further information is referred to the
original memoir [130&].

Rhaphidospora, Leger, 1900, for R. le danteci, Leg., parasite of the
intestinal cells of Olocrates gibbus. Specimens of this beetle, which belongs
to the family Tenebrionidae, are found, in which the epithelial cells of the
mesenteron are filled with rods resembling the rhaphides of plants, lodged
in vacuoles and arranged parallel to the axis of the cell. Each rod is
about 14 p. in length by 1-5 p. in breadth, and consists of a fine membrane
enclosing deeply-staining filiform elements, which apparently are four in
number, each with a chromatin granule. The filiform elements become
liberated and appear to multiply by transverse fission, but ultimately
they grow into rods, each at first consisting of finely granular protoplasm
and a nucleus containing a few chromatin granules. Each such body
then surrounds itself with a membrane, and its contents break up into
filiform elements. All stages of the parasite are capable of active move-
ments. The rods are probably the agents by which new hosts are infected,
through being swallowed with the food.

Chytridiopsis, Aimd Schneider, 1884, for C. socius, A. S., intracellular
parasite of the intestinal epithelium of Blaps mortisaga ; sometimes occur-
ring also within the Gregarine, Stylorhynchus longicollis, found in the
same host. The youngest stage of the parasite is a small spherical proto-
plasmic body, which, according to Schneider, is without a nucleus, but it
seems more probable, even from Schneider's figures, that it has numerous
small nuclei. The parasite grows to a certain size and then becomes
encysted. Within the tough, doubly-contoured cyst-envelope a zone of
cortical granular protoplasm is separated off, and within this cortical zone,
which appears to represent residual protoplasm, the body of the parasite
divides up into a great number of simple spherical spores, about 1'5 p. in
diameter and quite undifferentiated, forming a solid mulberry -like mass
occupying the centre of the cyst. By its spores and general appearance
Chytridiopsis seems to approach very nearly to the Haplosporidia.

Chitonicium, Plate, 1898, for C. simplex, Plate, parasite of the mantle-
cavity and the epithelium of the mantle groove, foot, and gills of Ischno-
chiton minator, and infecting also less abundantly Chaetopleura peruviana
and other chitons of Chili. It occurs as little oval or spherical cells,
each with a distinct nucleus and cell-membrane, which multiply actively
by direct amitotic division in the epithelial cells, causing great destruc-
tion amongst them. The parasites are also found free in the mantle-
cavity, and multiply in this situation, where Plate thinks it possible that

318 THE SPOROZOA

they may infect the eggs and embryos of the host, in which the mantle-
cavity acts as a brood-pouch. No other stages of the parasite have been
observed, since the spindle-shaped variety first described by Plate has
been found by him, on renewed investigation, to be in reality a patho-
logically modified form of the nuclei of the supporting cells of the mucous
frills. Since no method of sporulation has been shown to occur, this
parasite cannot as yet be enrolled amongst the Sporozoa.

Karyamoeba, Giglio-Tos, 1900, for K. renis, G.-T., an intranuclear
parasite (?) of the renal epithelium of Mus decumanus.

Nematopsis, A Schneider, 1892, for N. sp., parasite of the connective-
tissue cells of the mantle of Solen vagina. A single host-cell may contain
one, two, or three cysts, in each of which is lodged a little coiled-up
animalcule, resembling a tiny Nematode, but consisting apparently of a
single cell with one nucleus.

Schewiakoff, in 1893 [135], described, but without naming them,
certain " entoparasitic tubes " (Sclilauche) occurring in Cyclopidae (Cyclops
and Diaptomus spp.), where they had been discovered by Schmeil. These
parasites occur as amoebae, free in all parts of the body-cavity (haemocoele)
of the host. The amoebae (Fig. 127, a, b) vary in size from about 7 /x in
length by 3 /A in breadth, to 20 /x by 6 /A ; they send out lobose pseudo-
podia, and possess each a vesicular nucleus and a contractile vacuole, a
point in which they differ from all known Sporozoa. The contractions
of the vacuole take place at intervals of about 30 seconds. The amoebae
creep over the epithelial cells and the muscles ; and they were observed
to fuse with one another to form plasmodia (Fig. 127, h, i, j), varying in
size according to the number of individuals thus united. Since sometimes
plasmodia formed of two or three amoebae were observed later to contain
only a single nucleus, it is highly probable that nuclear fusion also takes
place in them. After a certain time encystment takes place, either of
single amoebae or of plasmodia. In the former case the cysts are
spherical (Fig. 127, c, d), containing one nucleus, and the contractile
•vacuole, which is visible for some time, its pulsations becoming slower.
The cyst-membrane has a double contour. The nucleus now becomes
divided up (Fig. 127, e), and the protoplasm becomes centred round the
daughter-nuclei to form oval spores (Fig. 127, /, g). The plasmodia
become encysted in a similar manner, but the cysts formed by them are
larger and oval in form, and the breaking up of the nucleus and other
preparations for spore-formation may take place while the plasmodia are
still free (Fig. 127, j, k, I). The spores are formed progressively in
the cysts ; a cyst formed from a single amoeba was observed to contain,
in about ten hours after the division of the nuclei was complete, six
spores imbedded in protoplasm containing numerous free nuclei ; twenty-
four hours later the number of spores was doubled, with undifferentiated
protoplasm and free nuclei still present in the cyst ; and after another
twenty-four hours the cyst was entirely filled by spores, with no residual
protoplasm or nuclei. The spore-formation in plasmodial cysts took
place in a similar manner. Each spore arises as a condensation of the
protoplasm round a free nucleus, and when fully formed is an oval or

THE SPOROZOA

319

pear-shaped body, 3-3 to 4 //, in length, strongly refringent and perfectly
hyaline in appearance, limited externally by a thin pellicle, and con-
taining a single nucleus at the broader end. The remarkable fact was

m

/ ?

^Jofe.---"

&

n-

/

^||^4 S&&f$98&e
**&* j

FIG. 127.

Phases of Schewiakoff's internal parasites of Cydopidat. a and 6, free amoebae; c, com-
mencement of encystation ; d, cyst with one nucleus ; e, cyst with many nuclei ; /, cyst one day
old, with six spores (sp) and a number of free nuclei («) ; g, cyst three days old, full of spores
in a residual matrix ; h, plasmodium with three nuclei ; i, the same later, with one nucleus ;
j, plasmodium preparing for sporulation, with numerous nuclei and vacuoles (vac) ; k, encysted
plasmodium, containing numerous spherical sporoblasts ; I, later stage of the preceding, the
sporoblasts having become ripe spores ; m-q, stages in the division of a spore ; r, small
amoebulae liberated from spores. (After Schewiakoff [135], a-l x 1500 ; m-r x 2600.)

observed that the spores multiply by fission in the cyst, their nuclei
dividing by a process of karyokinesis which Schewiakoff has studied and
figured in all its details, and which is followed by an oblique division of
the whole spore (Fig. 127, m-q). Besides spores dividing in this way,

320 THE SPOROZOA

Schewiakoff found others attached in couples by their anterior extremities,
and then frequently showing peculiarities in their nuclei which led him
to suspect that conjugation may also take place between spores, but he
was unable to confirm the existence of any such process. The spores
are set free by bursting of the cysts and are to be found sticking to the
muscles, but their further development was not followed, and it is not
known how the Cyclops becomes infected with them.

As regards the systematic position of these interesting parasites,
Schewiakoff thinks that " they should, without doubt, be placed amongst
the Sporozoa." If so, however, they differ from all known Sporozoa, first
in the possession of a contractile vacuole in the trophic stage, secondly
in their tendency to form plasmodia, and thirdly in the power of
multiplication by fission possessed by the spores. They have indeed a
certain superficial resemblance to the species of Thelohania which are
also parasitic on the muscles of Crustacea, but they differ from all
Myxosporidia in the simple, undifferentiated character of the spores,
a feature in which they resemble the Haplosporidia. If the Sporozoan
affinities of these parasites are, as they seem to be, undeniable, then they
must be regarded as quite the most primitive members of the group,
linking the Sporozoa in an unmistakable manner to the true Rhizopoda.

The systematic enumeration of the Sporozoa would not be complete
without mention of the very numerous forms of supposed parasites
described from various human diseases. A list of these doubtful organisms,
with full bibliographical references, will be found in Lab be ([4] pp. 128-
132), under the title " Pseudo-coccidies," and a bibliography, complete up
to 1899, is given by Hagenmtiller [3]. In the great majority of cases,
if not in all, it is very doubtful if these bodies are parasitic organisms
at all, so that to refer them definitely to the Sporozoa, and even to the
Coccidia, as is commonly done, is in the highest degree premature. It
is especially round the alleged parasites of cancer that the dispute has
been hottest. The natural eagerness to fathom the causes of the most
terrible of human diseases has produced a flood of literature in which the
" discovery " of a parasite, and in many cases of a Sporozoan parasite, has
been affirmed with complete confidence many times over. But although
Korotnef in 1893 gave a complete description of the cancer-parasite in
all phases of its life-history, under the name Rhopalocephalus carcino-
matosus, the opinion has been steadily growing, and is now held by
almost all zoological experts who have looked into the matter, that the
bodies which revealed themselves to Korotnef and others as cancer-parasites
are nothing more than cell-enclosures of various kinds, either degenera-
tions of structures normal to the cell, such as nuclei, " Nebenkerne," etc., or
products of abnormal cell-metabolism, supplemented perhaps by leucocytes
and other cells in various states of diseased activity and degeneration.
Recent expressions of zoological opinion have therefore been sceptical
towards the parasitic theory of cancer, relegating the parasites to the
realm of fable, or at least pronouncing decisively against their alleged
Protozoan nature (see Doflein [2a], pp. 8-11 ; Schaudinn [5 la], pp. 405-
408).

THE SPOROZOA 321

Kecently, however, the parasitic theory has been revived by Feinberg,1
who asserts that in sections of young growing cancerous tumours, before
the cells have begun to degenerate, there are to be found, between the
proliferating tissue-cells, structures consisting of a membrane enveloping
a protoplasmic body containing a nuclear corpuscle. Feinberg considers
that these bodies are intrusive organisms totally distinct from the tissue-
cells and their enclosures and products, and from his comparative studies
upon the structure of the nuclei in various animal and vegetable tissues
or unicellular organisms, he is further of the opinion that these parasites
are indubitable Protozoa. The parasitic theory of cancer is therefore by
no means dead yet ; but the Sporozoan nature of the alleged parasites is
far from being proved.

THE AFFINITIES AND PHYLOGENY OF THE SPOROZOA.

In recent times no zoologist has called in question the position
universally assigned to the Sporozoa amongst the Protozoa. The
attempts that have been made to establish kinship for them outside
this sub-kingdom can scarcely be said to belong to modern zoology.
The question remains, however, to which of the other classes of
Protozoa the Sporozoa are most nearly allied. Assuming, as every
evolutionist must, that all parasites are descended from free-living,
non- parasitic ancestors, the problem that presents itself is to.
determine as far as possible the nature and affinities of the
ancestral Sporozoa and their relationship to the three remaining
classes of Protozoa — the Rhizopoda, Mastigophora, and Infusoria
respectively. It may be said at once, however, that the Infusoria
(Ciliata and Suctoria) need not be considered in this connection,
since the Sporozoa exhibit no characteristics linking them specially
to this very well-defined group.

Two rival theories of Sporozoan ancestry have been put forward
by competent authorities — the one claiming for them descent from
the Rhizopoda, the other from the Mastigophora. In considering
these opposing views, it should be borne in mind at the outset
that the Rhizopoda and Mastigophora are two classes which are
connected by many links, and may be said almost to merge into
one another at certain points. Many Rhizopoda have swarm-
spores, or other stages in their life -cycle, which are flagellated ;
many Mastigophora, on the other hand, are amoeboid. Such forms
as Mastig amoeba can only be distinguished from true Rhizopoda
by the retention of a flagellum in the free stages of the life-cycle ;
were the flagellum lost, when adult, as in other cases, the organism
would be classed as a Rhizopod. The distinction between the two
classes is, therefore, somewhat arbitrary and artificial when the

1 " Zur Lehre des Gewebes und der Ursache der Krebsgeschwtilste," Deutsche med.
Wochenschrift, xxviii. (1902), No. 11 ; and other memoirs.

21

322 THE SPOROZOA

lowest members of them are taken into consideration. But the
forms further from the boundary-line, in each class, are distinct
enough, and if a typical member of either group be selected, such
as Amoeba for Rhizopoda, and Huglena, or some similar form, for
Mastigophora, we are confronted by two sharply contrasted types.
It would indeed simplify the comprehension of the two theories of
Sporozoan ancestry if they were termed the hypotheses of the
amoeboid and the euglenoid ancestry respectively.

Biitschli in his great work on the Protozoa ([1], p. 807) ad-
vanced the theory of the euglenoid ancestry. Given a typical
Flagellate which became adapted first to a saprophytic, and then
to a parasitic mode of life, it would tend as the result of parasitism
to become simplified in characters and to lose all special organs of
locomotion, nutrition, and sensation. An Euglena or Astasia,
deprived in this way of flagellum, mouth, chromatophores, stigma,
and vacuoles, nutritive or contractile, would be practically indis-
tinguishable from a simple Gregarine. Considered generally, the
body-form, cuticle, and contractile elements of the Gregarines are
very similar to those of the typical Flagellata, and the resemblance
of the "euglenoid" movements of Gregarines to those of "metabolic"
Flagellata has already been pointed out. The same is true also of
the motile stages of other Telosporidia; for example, the sporozoites
and merozoites of the Coccidia, the ookinete or "vermiculus" of
the malarial parasites, and the free haemogregarines of the Haemo-
sporea. Since Biitschli wrote, the discovery of flagellated stages
in many Telosporidia has given additional support to the Flagellate
theory, and has caused Wasielewski to pronounce in favour of it.

The theory of the euglenoid ancestry of the Sporozoa is, in
fact, based chiefly on certain characteristic features peculiar to the
Gregarinida and other Telosporidia; but when the attempt is
made to extend this hypothesis to the Neosporidia, the case is very
different. It must be admitted at once that the Neosporidia have no
euglenoid phases, and that the general facies of the group is strongly
Rhizopod-like, as pointed out by Doflein [100] and other investi-
gators. No Neosporidia are known to have flagella at any period
of their life-cycle, and, with the possible exception of the gymno-
spores of Sarcosporidia, none of their phases are euglenoid or
gregariniform. On the other hand, many of them are amoeboid,
and have the protoplasm naked, without any sort of cuticle or
envelope at the surface of the body, throughout the whole trophic
period. Typical Myxosporidia can, in fact, be regarded as Rhizo-
pods adapted to a parasitic mode of life. In their general features,
especially in the formation of the pseudopodia, the structure
and relations of the nuclei, and the alternation of generations, they
resemble, as Doflein remarks, the Foraminifera most nearly, an
indication, perhaps, of a common origin for the two groups. The

THE SPOROZOA 323

adaptive modifications induced by the parasitism are shown chiefly,
as in other parasites, in the increased fertility and elaboration of
the reproductive phases, the differentiation of the spores, and so
forth, points in which some forms are more advanced than others,
but in which all are highly specialised, as compared with free-
living Ehizopods.

Thus if the Telosporidia seem at first sight to afford some
support to the theory of descent from Flagellate ancestors, the
Neosporidia certainly do not, but exhibit most pronounced Rhizo-
pod affinities. There is, considered from this point of view, a
marked difference between the two subdivisions of the Sporozoa,
and those who are greatly impressed by the euglenoid features of
Gregarines and their allies might be tempted to postulate an
independent origin for each sub-class, and to derive the Telosporidia
from Flagellate, the Neosporidia from Rhizopod ancestors. But
even in the Telosporidia the evidence afforded by the amoeboid
character of the endoglobular Haemosporidia points very clearly
to Rhizopod ancestry, and the euglenoid phases of this sub-class
can be explained as derived from the primitive amoeboid type of
body in just the same way as the higher " metabolic " forms of
Flagellata, such as Euglena or Astasia, are related to primitive
amoeboid types, such as Mastigamoeba.

The conclusion is, therefore, that in the present state of our
knowledge it is simplest to regard all Sporozoa as descendants of
Rhizopod-like ancestors, modified by the parasitism to which they
are adapted. One immediate result of the changed conditions of
life is that they can dispense with all special organs for ingesting
or digesting food, since their nutriment is absorbed at the surface
of the body. Hence many Sporozoa have acquired a permeable
cuticle, and in consequence a fixed body -form. Such Flagellate
characteristics as Sporozoa possess, for example the flagellated
gametes of many Telosporidia, are found also among true Rhizo-
poda. To complete the argument in favour of Rhizopod ancestry,
attention may be drawn finally to the remarkable parasitic
amoebae described by Schewiakoff (supra, p. 318), which, if they
are really allied to the Sporozoa, seem to prove quite conclusively
the Rhizopod affinities of the group.

324

LIST OF SPOROZOAN HOSTS

LIST OF SPOKOZOAN HOSTS.

The following list is taken mainly from Labbe [4], with addi-
tions and corrections from works of more recent date : —

PROTOZOA.

Ceratium macroceros .

C. tripos and C. fusus
Ceratocorys horrida
Chlamydomonas sp.

Gregarines, various, especi-
ally Sycia inopinata,
Monoeystis mitis, Sele-
nidium spionis, etc.

Peridinium bipes

P. divergens
Stentor roeseli

Stylobryon petiolatum
Stylorhynchus longicollis
Volvox globator .

Epizoanthus glacialis .
Lucernaria auricula .

Chiridota pellucida

Cucumaria pentactes and C.

planci
Echinocardium cor datum and

E. flavescens
Holothuria impatiens .

H. nigra ( = H. forskalii ?) .
H. polii .

H. tubulosa
Spatangus purpureus .
Strongylocentrotus lividus .

Synapta digitata and S.
inhaerens

CNIDARIA.
Ovarian cells

ECHINODERMA.

Sporozob'n inc. sed. [L.

Pfeiffer, 1895].
Hyalosaccus ceratii, Keppene.

» i)

Sporozob'n, inc. sed. [L.

Pfeiffer, 1895].
Metchnikovella sp., Caull. et

Mesn.

Sporozoon inc. sed. [L.

Pfeiffer, 1895].

Hyalosaccus ceratii, Keppene.
Sporozoon inc. sed. [Stein,

1867.
Sporozoon inc. sed. [Saville

Kent, 1882].
Chytridiojrtis socius, Aim.

Schn.
Sporozob'n inc. sed. [Fro-

mentel, 1874].

"Gregarine" [Danielssen,

1890].
" Psorospermium " lucer-

nariae [Vallentin, 1888].

(Ant.

Blood-vessels and Cystobia holothuriae

coelom Schn.).

Respiratory trees G. sp. [fide H. M. Woodcock

and coelom in M.S.].

Coelom . . . Lithocystis schneideri, Giard.

Blood-vessels

coelom
Blood-vessels
Blood-vessels
coelom

»
Coelom .

and Cystobia schneideri, Ming.

. C. irregularis (Minchin).
and C. schneideri, Ming.

G. holothuriae (Ant. Schn.).
. Lithocystis schneideri, Giard.
. (?) Lithocystis schneideri,

Giard.
. Urospora synaptae (Cuenot).

LIST OF SPOROZOAN HOSTS

325

Brachycoelium sp.
Convoluta sp.
Dendrocoelum lacteum

Discocoelis tigrina
Mesostomum ehrenbergi

Planaria fusca and P. torva

Taenia bacillaris, T. denti-

culata, and T. expansa

PLATYHELMINTHES.

Parenchyma . . Pleistophora sp. [Le'ger, 1897].

Gut(?) . . . Urospora nemertis (Koll.).

,, " Gregarine " and " Coccidie "

[Hallez, 1 900]

,, . . . Ophioidina discocoelidis,M.ing.

Testes and rhab- Sporozoon inc. sed. [Ant.

dite-cells ' Schneider, 1873].

Gut . . . Pleurozyga planariae, Ming.

Parenchyma, go- Pleistophora helminthoph-

nads, ova thora (Kef.).

NEMERTINI.

Amphiporus cruciatus . Gut
Borlasia olivacea and B.

octoculata ; see Linens

gesserensis.
Carinella annulata . . Body-cavity .

Eupolia delineata
Linens gesserensis

Nemertes delineatus ;

Eupolia.

Ommatoplea sp. .
Valencinia sp.

. Gut

» . . .
. Posterior intestine

36

. Gut

Urospora nemertis (Kbll.).

"Monocystid Gregarine"

[Montgomery, 1898].
Urospora nemertis (Kbll.).

» »

"Gregarine" [Montgomery,
1898].

Urospora nemertis (Kbll.).

A scar is lumbricoides .
A. mystax .
Echinorhynchus protens
Oxyuris ornata .

NEMATHELMINTHES.

" Gregarina " sp. [Kuchen-

meister, 1855].
Gut, gonads . . Pleistophora helminthoph~

thora (Kef.).
" Gregarina " sp. [Henneguy,

1884].
Body-cavity . ."<?." sp. [Walter, 1858].

Sayitta daparedii

CHAETOGNATHA.
. Body-cavity .

S. sp Gut

Spadella bipunctata and <S'. Body-cavity .
serratodentata

ROTIFEEA.

Actinurus neptunius .

Asplanchna priodonta and Body-cavity .

A. sp.
Brachionus amphiceros, B. ,,

odn, B. pala, and B.

urceolaris

" Amoeba" pigmentifera

Grassi, and " A . " sagittae

Grass! .

Lankesteria leuckarti (Ming.).
' ' Amoeba " pigmentifera^

Grassi, and "A." sagittae,

Grassi.

Glugea sp. (? Bertramia)

. [Fritsch, 1895],
Bertramia asperospora

(Fritsch).

326

LIST OF SPOROZOAN HOSTS

Callidina parasitica . . Body-cavity .
Conochilus volvox , . ,, .

Hydatina senta . . . Stomach

„ „ . Gut

Philodinid sp. . . . Body-cavity .

Polyarthra platyptera . ,, . .

Synchaeta pectinata, S. ire- ,,

mula, and S. sp.

AECHIANNELIDA.
Ctenodrilus serratus . . Gut
Polygordius neapolitanus . ,,

Botellus (?) sp. [Plate, 1886].
Bertramia asperospora

(Fritsch).
' ' Monocystis " leydigi [Stein,

1867].
Botellus (?) sp. [Lenssen,

1897].
Bertramia

(Fritsch).

asperospora

Alciope sp.

Amphiglene mediterranea

Aphrodite aculeata

POLYCHAETA.

Coelom

Coelom, intestine

Gut

Aricia latreilli .
A. miilleri ; see Scoloplos
A. sp. ...
Audouinia filigera

A. lamarcki
A. sp.

>»

A. tentaculata .
Capitella capitata

Coelom
Gut

Capitellides giardi

Cirrhatulus cirratus .

C. filigerus ; see Audouinia,

Clymene lumbricalis .

Clymenella torquata .

Dodecaceria concharum

» »j • •

Eulalia punctifera
Eunice harassei .
Fabricia sabella .

Glycera sp. .

,,....

Heterocirrus viridis .

Jasmineira elegans

Coelom ,
Gut

Coelom .

Gut
Coelom .

» • •

Gut

Coelom, intestine

Coelom .
Gut" .
Coelom, intestine

Selenidium sp. (perhaps
echinatum), C. & M.

' ' Monocystis " foliacea [Frai-
pont, 1887].

Lobianchella beloneides, Ming.
Toxosporidium sabellidarum,

C. &M.
Doliocystis aphroditae

(Lank.).
Siedleckia nematoides, C. & M.

Selenidium sabellae (Lank.).
S. cirrhatuli (Lank.).
Ulivina elliptica, Ming.
Urospora iiemertis (Koll. ).
Gonospora terebellae (Kbll.).
G. varia, L^ger.
Sycia inopinata, Leger.
Selenidium sp., C. & M.
Ancora eagittata (Leuck.).
Bertramia capitellae, C. & M^.
" Coccidies " [Caullery &

Mesnil, 1897].
" Gregarine " [Caullery &

Mesnil, 1897].
Selenidium cirrhatuli (Lank.).

Pterosporamaldaneorum, Rac.

& Labbe.
" Monocystis " clymenellae,

Porter.

Selenidium echinatum, C.& M.
Gonospora longitsima, C. & M.
Urospora sp., Gravier.
Selenidium eunicae (Lank.).
Toxosporidium sabellidarum,

C. &M.

Ceratospora mirabilis, Leger.
Gonospora sparsa, Leger.
Haplosporidium heterocirri,

C. &M.
Toxosporidium sabellidarum,

C. & M.

LIST OF SPOROZOAN HOSTS

327

Lagis koreni
Liocephalus liopygus .

Lumbriconereis sp.
Myxicola,dinardensis .

Gut
Coelom .

Gut

Coelom, intestine

Nephthys scolopendroides . Gut

Nereis beaucoudrayi and JV.
eultrifera

Nerine sp

Notomastus lineatus .

Oria armandi
Phyllodoce sp.

Polydora agassizi
P. coeca
P.flava

Polymnia nebulosa
Pomatoceros triqueter .
Pygospio seticornis

Rhynchobolus americanus
Rhynchonerella fulgens

Sabella spp.
Scololepis fuliginosa .

Scoloplos miilleri

Serpula contortuplicata
Spio fuliginosus .
S. martinensis .

Intestine (?) .
Coelom, intestine

Coelom .
Gut

>!

Intestine (?) .

Testis .
Gut
Intestine (?) .

Gut

Gut

Epidermis
Gut

Coelom .

»
Gut

Staurocephalus rudolphii . ,,

Telepsavus costarum . ,,

Terebella sp. . . ,,

Joyeuxella toxoides, Brasil.
Pterospora maldaneorum,

Racov. & Labbe".
Doliocystis elongata (Ming.).
Toxosporidium sabellidarum,

C. & M.
Doliocystis heterocephala

(Ming.).
D. pellucida (Kb'll.).

Selenidium pendula, Giard.
" Coccidies " [Caullery & Mes-

nil, 1899].
Toxosporidium sabellidarum,

C. &M.

Gonospora sparsa, Leger.
Selenidium sp. [Claparede,

1861].

Doliocystis polydorae, Leger.
Selenidium sp., C. & M.
"Coccidies " [Caullery & Mes-

nil, 1897].

Caryotropha mesnilii, Siedl.
Selenidium sp., C. & M.
" Coccidies" [Caullery & Mes-

nil, 1899].

Selenidium sp., C. & M.
" Gregarina " sp. [Porter,

1897].
Selenidium annulatum

(Greeif.).

Selenidium sabellae (Lank.).
Doliocystis sp.
Selenidium sp.
Glugea laverani, C. & M.
Coccidian sp.
Selenidium sp.

Siedleckia nematoides, C. & M.
Haplosporidium scolopli,

C. & M.

Glugea laverani, C. & M.
Selenidium serpulae (Lank.).
S. spionis (Kbit. ).
"Coccidies " [Caullery & Mes-

nil, 1899].

Selenidium spionis (Kbll.).
Kollikerella staurocephali

(Ming.).
Gcm'ospora terebellae (Koll.).

Allolobophora terrestris

Clitellio sp.
Distichopus silvestris .

OLIGOCHAETA.

Vesiculae seminales Monocystis lumbrici (Henle);

M. magna, Schmidt ;

M. pilosa, Cue"n. ; and M.

porrecta, Schmidt.
Triactinomyxon ignotum,

Stole.
Gut . . . Monocystis mitis, Leidy.

328

LIST OF SPOROZOAN HOSTS

Eclipidrilus frigidus

Enchytraeus albidus, E.
galba, and E. hegemon
Limnodrilus claparedianus .
Lumbricus agricola

L. herculeus, L. olidus, L.
rubellus, etc.

Megascolex armatus
Nais lacustris
Pachydrilus pagenstecheri,

P. semifuscus
Perichaeta arinata ; see

Megascolex.
P. novaezealandiae.

Phoenicodrilus taste .

Phreatothrix pragensis
Psammoryctes barbatus

Rhynchelmis obtusirostris

Tubifexrimlorum; see T.

tubifex.
T. tubifex .

Blood - vessels and

mesentery
Vesiculae seminales

Vesiculae seminales
and coelom

Coelom .

Coelom and vesicu-
lae seminales

Vesiculae seminales
Vesiculae seminales

Haemogregarina nasuta

(Eisen).
Spermatophagus eclipidrili

(Eisen).
Monocystis enchytraei, Kb'll.

Myxocystis ciliata, Mrazek.
Zygocystis cometa, Stein.

Monocystis agilis, Stein

( = lumbrici, Henle) ; M.

magna, Schmidt ; M.

pilosa, Cuen. ; and M.

porrecta, Schmidt.
M. perichaetae (Bedd.).
J/2/ax>&oZwssp.[Biitschli, 1882].
Monocystis pachydrili (Clap. ).

Coelom. . . " Coccidium " sp. [Beddard,
1888].

Seminal vesicles . Monocystis perichaetae (Bed-
dard).

Vesiculae semiiiales Spermatophagus freundi

(Eisen).

,, Gregarine [Vejdovsky, 1876].

Hexactinomyxon psammu-
ryctis, Stole.

Coelom. . . "'Monocystis" sp. [Menge,
1845],

Vesiculae seminales Urospora saenuridis (Kbll.).
and coelom

Synactinomyxon tubificis,
Stole1.

HlRUDINEA.

Glossiphonia complanata Coecaofgut. . " Gregarina " sp. [Bolsius,

( = G. sexoculata) . . 1895].

Haementeria officinalis . Coelom and con- ,, ,,

junctive tissue

. Coeca of gut . ,, ,,

see

Herpobdella atomaria .
Nephelis atomaria ;

Herpobdella.
Piscicola geometra

Haemocoele

Bonellia viridis .
Echiurus pallasi
Sipunculus nudus
Thalassema sp. .

GEPHYREA.

Gut

»
Coelom

Ophioidina bonelliae (Frnz.).
Zygosoma gibbosum (Greetf. ).
Urospora sipunculi (Koll.).
Monocystis thalassemae, Lank.

Alcyonellum fungosum

POLYZOA.

Sperm - cells and Glugea bryozoides (Korotnef).
body-cavity

LIST OF SPOROZOAN HOSTS 329

CRUSTACEA.

Asdlus aquaticus . . Ectoparasitic . Amoebidium parasiticum,

Cienk.

Astacus astacus . . . Muscles . . Thelohania contejeani, Henn.

,, ,, . . . Intermuscular coil- " Psorospcrmium " haeckeli,

nective tissue Hilgd.

Balanus improvisus, var. Gut . . . " Gregarina " sp. [Solger,

gryphicn 1891].

B. perforatus . . ., . . . Nematoides fusiformis, Ming.

B. pusillus and B. tintinaa- ,, ... " Gregarina " balani, Kbll.

bulum
Cancer pagurus . . . Gut and ovarian Aggregates, praemorsa (Dies.).

appendage
Candona Candida . . Body-cavity . . Blanchardina cypricola

(Wrzski.).

,, ,, . . ,, . . . Botellus parvus, Monz.

Cant/iocamptus minutus . Gut . . . " Monocystis " lacryina, Vejd.
Caprella sp. . . ,, . . . Aggregata caprellae (Frnz.).

Carcinus maenas . • ,, • . • A. portunidarum, Frnz.
Ceriodaphnia quadrangula . Ectoparasitic . Amoebidium moniezi, Labbe".
,, ,, ... Pleistophora sp. [Fritsch,

1895].

C. reticulata , . . Ectoparasitic . Amoebidium cienkowskianum,

Monz.

,, ,, . . . Body-cavity. . Pleistophora obtusa (Monz.).

, , , , . . . Gonads and haemo- Botellus typicus, Monz.

coele

Chydorus sphaericus . . Body-cavity. . Pleistophora obtusa (Monz.).
,, ,, . Body-cavity, gut, Coelosporidium chydoricola,

and dorsal Mesn. et March,

organs
, , , , . . Gonads and haemo- Botellus typicus, Monz.

coele

Crangon crangon . . Muscles . . Thelohania giardi, Henn.
Cyclops gigas . . . Body - cavity and Pleistophora virgula (Monz.).

fat-body
C. macrurus . . . ... "Monocystis'' mobilis (Rehb.).

C. phaleratus . . . Body-cavity . . Entoparasitic amoebae [Sche-

wiakoff, 1894].
C. rubens; see Diaptomus sp.
C. strenuus . . . ... Pleistophora rosea (Fritsch).

C. sp. . . . . Haemocoele and fat- (?) P. obtusa (Monz.).

body
,, .... ,, P. virgula (Monz.).

,, .... Body-cavity. . Entoparasitic amoebae [Sche-

wiakoff, 1894].

Cypris Candida; see Can-
dona.

C. jurini ; see C. strigata.
C. ophthalmica . . . , , . . ( ?) Botellus parvus, Monz.

„ . . . ... Pleistophora sp. [Wierzejski,

1890].

C. ornata ; see C. virens.
C. punctata ; see C. oph-
thalmica.
C. sp. . . . . ... Pleistophora sp. [Wierzejski,

1890].

. Body-cavity . . Serosporidium cypridis, L.
Pfr.

330

LIST OF SPOROZOAN HOSTS

Cypris sp. .

C. strigata .
C. vidua

C. virens

Daphnia kahlbergiensis

D. longispina
D. maxima .
D. pulex

. Body-cavity

. Body-cavity

. . Haemocoele
. Hypodermis

. Body-cavity

D. rectirostris ; see Moina.
D. reticulata ; see Cerio-

daphnia.
D. sima ; see Simocephalus

vetulus.
Diaptomus gracilis

D. salinus
D. sp.

D. vulgaris
Dromia dromia .
Eurycercus lamellatus
Gammarus locusta

G. pulex

Ectoparasitic
abdomen

Body-cavity .

Gut

Ectoparasitic

Gut

Muscles
Body-cavity .

Ectoparasitic

G. puteanus ; see Niphargus

subterraneus.
Heterocope sp.

Holopedium gibberum

Homarus gammarus .
Hyale pontica
Lathonura rectirostris

Limnetis sp.

Lynceus sphaericus ;

Ghydorus.
Moina rectirostris

Blanchardina cypricola

(Wrzski.).

Serosporidium sp., L. Pfr.
Pleistophora sp. [Wierzejski,

1890].

Botellus parvus, Monz.
Serosporidium miilleri, L. Pfr.
Pleistophora sp. [Fritsch,

1895].

P. obtusa (Monz.).
Gurleya tetraspora, Dofl.
Pleistophoracoccoidea(L. Pfr.).
P. obtusa (Monz.) ; P. (?) vir-

gula(M.onz. ), and Botellus

daphniae (L. Pfr.).

P. colorata (Fritsch).
Amoebidium moniezi, Labbe.

Pleistophora schmeili (L. Pfr.).
" Monocystis" mobilis (Rehb.).
Entoparasitic amoebae [Sche-

wiakoff, 1894].

Pleistophora schmeili (L. Pfr.).
Aggregata dromiae (Frnz.).
Amoebidium crassum, Monz.
Monocystid Gregarine

[Original observation].
Didymophyes longissima,

Sieb.
" Gregarina" sp. [L. Pfeiffer,

1895].

Thelohania mulleri (L. Pfr.).
Serosporidium gammari, L.

Pfr.
Amoebidium parasiticumf

Cienk.

Heart, haemocoele,

gut
Gut

>i . . .
Ectoparasitic

Hypodermic cells .

Pleistophora sp. [FridS and

Vavra, in Pfeitfer, 1892].

P. holopedii (Fri6 and Vavra).

Porospora gigantea (v. Ben.).
Aggregata nicaeae (Frnz.).
Amoebidium cienkowski-

anum, Monz.
Pleistophora coccoidea (L. Pfr.).

Nebalia serrata .

Nicaea nilsoni ; see Hyale
pontica.

Body -cavity .
Gonads and haemo-
coele
Gut

Pleistophora obtuaa (Monz).
Botellus typicus, Monz.

Septate Gregarine [Original
observation].

LIST OF SPOROZOAN HOSTS

S3'

Niphargus subterraneus
Notodromas monacha

Orchestia littorea

Gut .
Body-cavity .

Gut

Pachygrapsus marmoratus . ,,
Palaemon aspersus and P. Muscles

serratus

P.rectirostris ; see P. aspersus.
Palaemonetes varians . . ,,
Paradoxostoma sp.

Pasithea rectirostris ,

Lathonura.
Phronima sedentaria .

P. sp. .

Phronimella sp. .
Pinnotheres pisum
Pollicipes cornucopia .
P. polymerus

Polyphemus sp. .
Portunus arcuatus

Sapphirina sp. .
Simocephalus vetulus

Typton spongicola

Peripatus capcnsis

. Shell and body

ee

. Stomach

. Gut

» •

. Body-cavity .
. Gut

Body-cavity .
Gut

Ectoparasitic

Body-cavity .
Gut

ONYCHOPHORA.

. Gut

Zygocystis puteana, Lachni.
Blanchardina cypricola

(Wrzski.).
(?) Didymophyes longissima,

Sieb.

Aggregata conformis (Dies.).
Thelohania octospora, Henn.

T. macrocystis, Gurley.

Pleistophora sp. [G.

Miiller, 1894].

W.

Callyntrochlamys phronimae,

Frnz.
" Gregarina" clausi, Frnz.

)> »

Aggregata coelomica, Leger.
Nematoidesfusiformis,Ming.
1 ' Gregarina " valettei, Nuss-

baum.

Pleistophora obtusa (Monz.).
Aggregata portunidarum,

Frnz.

Zygocystis yortuni (Frnz.).
Ophioidina haeckeli, Ming.
Amoebidium cienkowski-

anum, Monz.

Pleistophora obtusa (Monz.).
Callyntrochlamys sp.[Gabriel,

1880].

, 1874].

MTRIAPODA.

Cryptops hortensis

C. punctatus

C. sp. ...

Fontaria virginiensis .

Geophilus ferruginosus
G. sp. ...

Gut

Glomeris guttata and G. Malpighian tubes

ornata ....

G. marginata . . . Testis .

G. sp Gut

Himantarium gdbrielis
Julus marginatus ;
Spirobolus.

Dactylophorus robustus

(Leger).

Klossia bigemina (Labb4).
" Eimeria " trigemina

[Leger, 1897].
"Gregarina" polydesmivir-

giniensis, Leidy.
Coccidium pfeifferi (Labbe).
Rhopalonia geophili, Leger ;

Coccidium sp. [Leger,

1897] ; Cyclospora sp.

[Leger, 1896].
Legerella nova (Aim. Schn.).

L. testiculi, Cuen.

Cnemidospora lutea, Aim.
Schn. ; Cyclospora glo-
mericola, Aim. Schn.

Coccidium simondi (Leger).

332

LIST OF SPOROZOAN HOSTS

Julus pusillus . . . Gut

J. sabulosus and J. terrestris ,,

LithoMus castaneus . . ,,

L. forficatus . . , ,

L. hexodus ....

L. impressus

L. martini ....

L. mutabilisa.n^.L.pijrenaicus

L. pilicornis

Polydesmus complanatus

P. sp

P. virginiensis ; see Fontctria.
Polyxenus lagurus

Scolopendra cingulata .

S. morsitans
Scolopocryptops sexspinosus .

Scutigera forceps
S. sp. .

Spirobolus marginatus
Stigmatogaster gracilis

Proventriculus
Gut

HEXAPODA.

Acheta abbreviata (Orthopt.) Proventriculus,

body-cavity (?)
Agrion puella, larva Gut

(Neuropt. )
Akis acuminata and A. al- Malpighian tubes .

geriana (Coleopt.)
A. sp. ...

Amara cuprea (Coleopt. )
Anopheles spp. (Dipt.)

Gut

Fat-body

Gut ...

Stomach, haemo-

coele, salivary

glands

Antherea pernyi, larva (Lepi-

dopt.)
Anthrenus museorum, larva Gut

(Coleopt.)
Aphis arundinis ; see Hya-

lopterus.

"Gregarina" julipusilli,

Leidy.

Stenophora juli (Frantz).
Coccidium simondi (Leger).
Actinocephalus dujardini,

Aim. Schn.
Echinomera hispida, Aim.

Schn.

Ade.Ua ovata, Aim. Schn.
Barroussia alpina, Leg.
Coccidium schubergi, Schaud. ,

and C. lacazei (=Ban-

anella lacazei, Labbe +

Eimeria schneideri, Biit-

schli).

Echinosporaventricosa, L^ger.
Barroussia schneideri, Leger.
B. caudata, L6ger.
Echinospora labbe'i, Leger.
Coccidium simondi (Leger).
Amphoroides polydesmi

(Le"ger).
Diaspora hydatidea, Leger.

Gregarine [Leger & Duboscq,

1900].
Adelea dimidiata (Aim.

Schn.) ; Pterocephalus no-

bilis, Aim. Schn.
A. dimidiata (Aim. Schn.).
"Gregarina" actinotus

[Leidy, 1889].
" G." megacephala, Leidy.
Trichorhynchuspulcher, Aim.

Schn.

Stenophora juli (Frantz).
Rhopalonia geophili, Leger ;

Coccidium hagenmulleri,

L^ger.

Gregarina achetae • abbrevia-

tae, Leidy.
Menospora polyacantha, Leg.

Ophryocystis francisi, Aim.
Schn.

Sphaerorhynchus ophioides
(Aim. Schn.)>

Adelea akidium, Leger.

Gregarina amarae, Frantz.

Laverania malariae, Gr. et
Fel. ; Plasmodium ma-
lariae ( La v. ) ; and P. vivax
(Gr. etFel.).

Glugea sp. [Balbiani, 1882],

Pyxinia mobiuszi, Leg. & Dub.

LIST OF SPOROZOAN HOSTS 333

Aphodius nitidulus and A. Gut . . . Didymophyes leuckarti, W.

prodromus (Coleopt.) St. Marshall.

Airismelliferaffiywenoipt.) Muscles . . Glugea sp. [Leydig, 1863].

Asida grisea (Coleopt. ) . Gut . . . Stylorhynchus oblongatus

(Hamm.).

A. servillei. . . • ,, . . . Eirmocystis asidae, Leger.
Attacus pernyi ; see Antherea.

Attagenus pellio, larva ,, . . . Pyxinia frenzeli, L. & M.

(Coleopt. )

Bibio marci, larva (Dipt.) . ,, . . . Schneideria mucronata, L4g.

Blabera claraziana(0rthopt.) ,, . . Pileocephalus blaberae (Fren-

zel).

Blaps magica (Coleopt. ) ,, . . . Ophryocystisschneiderifljeger.

B. mortisaga . . • ,, • . • Stylorhynchus longicollis, F.

St.
,, ... Malpighian tubes . Ophryocystis butschlii, Aim.

Schn.

„ ... Epithelium of gut . Chytridiopsis sotius, Aim. Schn.

Bombyx muri, larva All organs . . Glugea bombycis (Nageli).

(Lepidopt. )

Brassolis astyra (Lepidopt.) Gut, Malpighian G. astyrae (Lutz & Splendore).

tubules, spin-
ning glands,
gonads
Calliphora vomitoria (Dipt.) Head, thorax, "Pe'brine" [Vosseler, 1897].

blood (?)
Calopteryx virgo, larva Gut . . . Hoplorhynchus oligacanthus

(Neuropt.) (Sieb.).

Carabus auratus (Coleopt. ) ,, . . . Actinocephalus stelliformis,

Aim. Schn. ; Ancyrophora
gracilis, Leger.

,, ,, Body -cavity . . Mimocystis Ugeri, L. F. Blan-

chard.

C. glabratus . . . Gut . . . Actinocephalus aciis, Stein.

C. violaceus . . • ,, • • .A. stelliformis, Aim. Schn. ;

Ancyrophora gracilis,
Leger.

Catopsilia eubule (Lepidopt.) Gut, Malpighian Glugea, eubulcs (Lutz & Splen-

tubules, spin- dore).

ning glands,
gonads
Ceratopogon sp., larva Gut . . . Schizocystisgregarinoides,'Leg.

(Dipt.)

Cetcmia aurata (Coleopt.). ,, . . . Gregarina curvata (Hamm.).

Chironomus sp., larva ,, . . . Schneideria sp. [L^ger, 1899].

(Dipt.)
Chlaenius vestitus (Coleopt.) ,, . . , Actinocephalus digitatus. Aim.

Schn.
Chrysomela haemoptera and ,, . . . Gregarina munieri (Aim.

C. violacea (Coleopt. ) Schn. ).

C. populi ; see Melasoma.
Coccus hesperidum ... Glugeidae [Leydig, 1854].

(Homopt. )

" Coleoj)ttre hydrocanthare " . Gut . . . Coccidium hyalinum, Leger.
Colymbetes sp., larva ,, . . . Legeria agilis (Aim. Schn). ;
(Coleopt.) Ancyrophora uncinata,

Leg.
Corynetes ruficollis ; see

Necrobia.

Clenophorasp., larva (Dipt). ,, (?) Actinocephalus sp. [Le^er,

1899].

334

LIST OF SPOROZOAN HOSTS

Culexspp. (Dipt.)

larva

Cyphon pallidus,

(Coleopt.)
Danais crippus and D.

gilippus (Lepidopt.)

Decticus griseus ; see Platy-

cleis.

Dermestes lardarius (Coleopt)
D. I., larva
D. peruvianus
D. undulatus, larva
D. vulgaris (?)
D. vulpinus
Dionejuno (Lepidopt.)

Stomach, haemo- Haemoproteus danileivskyi,

coele, salivary Kruse.

glands

Gut . . . Sphaerocystis simplex, Leger.

Gut, Malpighian Glugea erippi [errore grippi]
tubules, spin- (Lutz & Splendore).

ning

Gut . . Pyxinia rubecula, Hamm.

. Beloides firmus (Leger).

. Pyxinia crystalligera, Frnz.

. Beloides tenuis (Leger).

. Pyxinia crystalligera, Friiz.

, . P. rubecula, Hamm.

Gut, Malpighian, Glugea junonis (Lutz &
tubules, spin- Splendore).

ning

D. vanillae ,

Gut

Carolina

Dissosteira

(Orthopt.)
Dorcus parallelepipedus

(Coleopt.)

Dytiscus sp., larva (Coleopt.)
EctoMa lapponica (Orthopt. )
Ephemera sp., larva

(Neuropt.)

Forficula auricularia

(Orthopt.)
Gastropacha neustria, larva

(Lepidopt.)
Geotrupes stereorarius

(Coleopt. )
Gryllotalpa gryllotalpa

(Orthopt.)
G. sp

Gryllus

(Orthopt.)
G. domesticus

campestris

G. sp

G. sylvestris ; see Nemobius.
Gyrinus natator, larva

(Coleopt. )
G. sp., larva

Helops striatiis (Coleopt.) .

Hoploce/ihala bicornis

(Coleopt.)

All organs
Gut

>» •
Midgut .

Gut

Body-cavity
Gut

G. vanillae (Lutz &

Splendore).
Gregarina locustaecarolinae

Leidy.
Stephanophora lucani (F. St.).

Ancyrophora uncinata, Leger.
Gamocystis tenax, Aim. Schn.
Gregarina granulosa (A.

Schn.).

Gamocystis ephemerae (Frantz).
( = G. francisci,A.. Schn.).
Gregarina ovata, Duf.

Glugea bombycis (Nageli).
Didymophyes paradoxa, F. St.

Eirmocystis gryllotalpae,
Leger.

Glugea sp. (Lutz & Splen-
dore, 1903).

G. sp. (Vlacovitch, 1867).

Gregarina gryllorum, Cuen.,
and G. macrocephala (A.
Schn.)

Diplocystis major, Cuen. ; and
D. minor, Cuen.

Gregarina davini, Leg. & Dub.

Corycella armata, Leger.

Adelea simplex (Aim. Schn.) ;

"Eirneria " hirsuta, Aim.

Schn.
Lophocephalus insignis (Aim.

Schn.).
Gregarina, microcephala

Leidy

LIST OF SPOROZOAN HOSTS

335

arundinis

Hyalopterus

(Homopt.)
Hydaticiis sp. (Coleopt. )

Body - cavity and

fat-body
Gut

Hydrobius sp. , larva

(Coleopt. )
Hydrophilus piceus larva

(Coleopt.)
Hydrous caraboides, larva

(Coleopt.)
H. sp. larva
Lecanium hesperidum

(Homopt.)

Lepisma saccharina (Apt.) .
Libellulidae,varioiis, nymphs

(Neuropt. )
Limnobia sp., larva (Dipt.).

Limnophilus rhombiciis, larva

(Neuropt. )
Locusta Carolina; see Disso-

steira.
Lophocampa flawstica (Lepi-

dopt. )

Lucanus paralleUpipedus ;

see Dorcus.

Machilis cylindrica (Apt. )
Mechanites lysimnia (Lepi-

dopt. )

Melasoma populi (Coleopt.)
Melolontha brunnea (?)

(Coleopt.)
M. sp., larva
Morica sp. (Coleopt. )

Body- cavity
Gut

Neozygitis aphidis, Witl.

Bothriopsis histrio, Aim.

Schn.
Cmnetoides crinitus (Le"ger).

Phialoides ornata (Leger).

Acanthospora polymorpha,

Leger.

Cometoides capitatus (Leger).
Sporozob'n inc. sed. [Ley dig,

1853].

Gregarina lagenoides (Leger).
Geneiorhynchus monnieri, A.

Schn.
Eirmocystis polymorpha,

Leger.
Ancyrophora uncinata, Leger.

Gut, Malpighian
tubules, spin-
ning glands,

Gut ...

Gut, Malpighian
tubules, spin-
ning glands,
gonads

Malpighian tubes

Gut

Mystacides sp. (Neuropt.)
M. sp., larva

NecroMa ruficollis (Coleopt. )
Nenwbius silvestris (Orthopt. )

Nepa cinerea (Hemipt.)

Body-cavity and

fat-body
Gut

Nyctobates pennsylvanica Proventriculus

(Coleopt.)
Ocypus olens (Coleopt.) Gut

Olocrates abbreviatus

(Coleopt.)

Glugea lophocampae (Lutz &
Splendore).

Hyalospora a/finis, Aim. Schn.
Glugea lysimniae (Lut/. &
Splendore).

G. sp., L. Pfr.

Gregarina melolonthac-

brunneae, Leidy.
Stictosporaprovincialis, Leger.
Oocephalus hispanus, Aim.

Schn.
Gregarina mystacidarum

(Frautz).
Pileocephalus chinensis, Aim.

Schn.

P. bcrgi (Frnz.).
Gregarina macrocephala, A.

Schn.
Coleorhynchus heros (Aim.

Schn.)
Syncystis mirabilis, Aim.

Schn.
Barroussia ornata, Aim. Schn.

( — Eimeria nepae, Aim.

Schn.)
Gregarina pkilica, Leidy.

Actinoccphalus stelliformis,

Aim. Schn.
" Glugea" sp. [Frey& Lebert,

1856].
Adelea akidium, Leger.

336 LIST OF SPOROZOAN HOSTS

Olocrates gibbus . . . Intestinal epi- Rhaphidospora le danteci,

thelium Leger.

,. ,, Malpighian tubes Ophryocystis hagenmulleri,

Leger.

Omoplus sp. , larva (Coleopt. ) Gut . . . Acanthospora pileata, L^ger.
Opatrum sabulosum ,, . . . Stylorhynchus oblongatus

(Coleopt.) (Hamm.).

Orchesella villosa (Apt.) ,, . . . Gregarina podurae (Leger).

Oryctes nasicornis, larva ,, . . . Didymophyes gigantea, F. St.

(Coleopt.)

Pachyrhina pratensis (Dipt. ) ,, . . . Eirmocystis ventricosa, Le"g.
,. ,, Fat-body, connec- Glugea stricta (Monz.).

tive tissue, and
muscles

Pamphagus sp. (Orthopt.) Gut . . . Gregarina acridiorum(L6g<ir).
Panchlora exoleta (Orthopt.) ,, . . . G. panchlorae, Frenzel.
Parnus sp. (Coleopt.) . ,. . . . (?. laucournetensis (Aim.

Schn.).

Passalus cornutus (Coleopt.) Proventriculus . G. passalicornuti, Leidy.
Periplaneta americana Body-cavity . Diplocystis schneideri, Kunstl.

(Ortbopt.)
,, ,, Gut and Malpighian Glugea periplanetae (Lutz and

tubules Splendore).

P. orientalis . . , Gut . . . Gregarina blattarum Sieb. ;

G, blattaeorientalis, Leidy.

,, ,, ... Glugeidae [Schaudinn, 1902].

Petrobius maritimus (?) (Cole- Gut . . . Hyalospora roscoviana, Aim.

opt. ) Schn.

Phryganea grandis, larva , , • . . Asterophora elegans, Leg.

(Neuropt. )

P. rhombica; seeLimnophilus.
Phryganeidae, larvae . • . Gut . . . Pileocephalus heerii (Kbll.).

,, ,, Ectoparasitic . Amoebidium parasiticum,

Cienk.

Phyllognathw sp. (Coleopt.) Gut . . . Didymophyes gigantea, F. St.
Phymata crassipes (Hemipt.) ,, . . . Gregarina soror, Duf.
Pierid sp. (Lepidopt.) . . .... Glugea sp. [Lutz and

Splendore, 1903].
Pimelia sp. (Coleopt. ) ,, . . . Cystocephalus algerianus, Aim.

Schn.
Platycleis grisea (Orthopt.). ... Glugea sp. [Balbiani, 1882].

Podura aquatica ( Apt. ) . Gonads . . . G. thysanurae (L. Pfr.).

P. villosa; see Orchesella.

Poecilus cupreus ; see Amara.

Porthesia chrysorrhoea (Lepi- Mid-gut . . G. sp. [Frenzel, 1885].

dopt. )
Potamanthus sp., larva Gonads, ova, and (?) G. sp. [L. Pfeitl'er, 1895].

(Neuropt.) fat-body

Pyralis viridana ; see

Tortrix.
fieduviiis personatiis Gut . . . ffyalosporareduvii(Ra,mdohr).

(Hemipt. )
Rhizotrogus aestivus (Cole- ,, . . . JSuspora fallax, Aim. Schn.

opt.)

R. sp., larva . . ,, . . . Stictospora provincialis, Leg.;

Actinocephalus stelli-
formis, Aim. Schn.
Rhyacophila sp. , larva , , . . . Asterophora mucronata, Leg.

(Neuropt. )

Sarcophaga carnaria (Dipt.) Head, thorax, " Pelrine" [Vosseler, 1897].

blood (?)

LIST OF SPOROZOAN HOSTS

337

Scarabaeus relictus (?), larva Gut

(Coleopt.)

Scaurus tristis (Coleopt.) . Malpighian tubes
Sciara nitidicollis, larva Gut

(Dipt.)
Sericostoma sp. larva ,,

(Neuropt.)

Silpha laevigata (Coleopt. ) , ,

S. thoracica, larva . , ,
Simulium ornatum, larva

(Dipt.)

Sminthurus sf. (Apt.)

Sphingonotus sp. (Orthopt.) „
Staphylinus olens ; see

Ocypus olens.

Statira unicolor (Coleopt. ) , ,

,, ,, . . Malpighian tubes

Tanypus sp., larva (Dipt.) Gut

Tenebrio molitor (Coleopt. ) , ,

,, ,, . Malpighian tubes

T. m., larva . . . Gut

Termes flavipes (Neuropt.) ,,

Thanasimus formicarius, ,,

larva (Coleopt.)

Timarcha tenebricosa (Cole- .,

opt.)

Tineola biselliella (Lepi- Body-cavity

dopt.)

Tipula oleracea (Dipt. ) . Gut

T. sp., larva . . ,,

T, pratensis ; see Pachyrhina.

Tortrix viridana (Lepi- Body-cavity

dopt.)
Tridactylus variegatus Gut

(Orthopt. )

Trox perlatus (Coleopt. ) ,,

Truxalis sp. (Orthopt.) ,,

Vanessa urticae, larva (Lepi-

dopt. )

Vespa media (Hymenopt. )
Zygaena filipendulae (Lepi-

dopt.)

Malpighian tubes
Fat - body, connec-
tive tissue, and
muscles

Gregarina scarabaeirelicti,

Leidy.

Ophryocystis caulleryi, Leger.
Schneideria caudata (Sieb.).

Discorhynchus truncatus

(Leg). ; Asterophora

elegans, Leg. ; Ancyro-
phora uncinata, Leg.

Actinocephalus acutispora,
L6ger.

Ancyrophora gracilis, Lfcger.

Glugea varians, Leg.

( ?) Glugea thysanurae (L. Pfr. ).
Gregarina acridiorum (Leger).

G. statirae, Frnz.

Glugea sp. [Frenzel, 1892].

Stylocystis praecox, Leg.

Sty lor h ynchus ovalis, Stein.

Ophryocystis mesnili, Leger.

Gregarina pulymorpha

(Hamm.) ; G. cuneata,
Stein ; G. steini, Berndt.

" G." termitis, Leidy.

G. longirostris (Leger).

G. munieri (Aim. Schn.).
Adelea mesnili, Perez.

Eirmocystis ventricosa, Leg.

Gregarinalonga(Ug) ; Actino-
cephalus tipulae, Leg. ;
Adelea tipulae, Leg.

Chloromyxum diploxys

(Gurley).
Gregarina hyalocephala, Duf.

G. acuta (Leger).

G. acridiorum (Leger).

(?) Gymnospora nigra, M^onz.

Glugea sp. [L. Pfeiffer, 1^95].
G. stricta (Monz.).

Acarine, marine .

ARACHNIDA.
Ecto parasitic

Exosporidium marinum,

Sand.
Aranea diadema ( = Epeira Heart and trunk Glugea sp. [Leydig, 1885].

d. ) muscles

Boophilus bovis ; see Rhipi-

cephalus annulatus.

Dermacentor reticulatus . ... Piroplasma canis (P. et G. V. ).

Haemaphysalis leachi . . ... ,, ,,

338

LIST OF SPOROZOAN HOSTS

Hydrachnid sp.
Phalangidae, spp.

Phalangium cornutum

P. crassum .
P. opilio

Ehipicephalus annulatus

Chiton faseicularis
C. sp .

Donax sp.
Eledone moschata

Gut

MOLLUSCA.

Liver

Mantle .

Kidney .
Gut

Helix arbustorum ; H. Kidney .

fruticum ; H. hispida ;

H. hortensis ; H. nemo-

ralis ; H. umbrosa
H. hortensis

Limax cinereo-nigcr
Neretina fluviatilis
Octopus vulgaris .

Kidney (?)
Kidney .
Gut

Patella vulgata
Pterotrachea sp.

Sepia offidnalis

Liver .
Body-cavity

Gut

Solen vagina

Mantle

Succinea gigantea (?) ; S. Kidney
pfeifferi ; S. putris

Tellina sp.
Trochv.s sp.

Liver

Glugea sp. [Lutz & Splendore,

1903].
Sciadophorafissidcns (Rbssler) ;

Stylorhynchus caudatus,

Rossi.
S. phalangii (Leger) ;

Acanthospora repelini,

Leger.

S. phalangii (Leger).
S. goronowitschi (Johansen) ;

Anthorhynclius sophiae

(Aim. Schn.) ; Acantho-

spora repelini, Leger.
Piroplasma bigeminum (Sm.

&K.).

Minchinia chitonis (Lank.).

Chitonicium simplex [Plate,
1901].

Hyaloklossia pelsenecri, Leger.

Eucoccidium octopianum (Ai.
Schn.) ; (Bencdenia octo-
piana, see nnder Octopus).

Klossia helicina, Aim. Schn.

Pfeifferella sp. [J. J. Clarke,
1895].

Isospora rara; Aim. Schn.

Klossia soror, Aim. Schn.

Eucoccidium octopianum (Ai.
Schn.) = Benedcnia sen
Legcria (Blanchard), seu
Klossia (Labbe), seu
Ltgerina (Jacquemet),
octopiana, with 10 - 12
sporozoites [Jacquemet,
1903 ; cp. Llihe, 1902].

Minchinia sp. [Labbe, 1896].

Gregarina pterotrachcae

(Stuart).

Eucoccidium ebcrthi (Lablie")
= J5enedenia (A. Schn.)
seu Klossia (Labbe), seu
Lfycrla (Blanchard), seu
Lfyerina (Jacquemet),
cberthi (Labbe), seu octo-
piana (Ai. Schn.), with
3 or 4 sporozoites
[Jacquemet, 1903 ;• cp.
Liihe, 1902].

Nematopsis sp. [Aim.
Schneider, 1892].

Klossia helicina, Aim. Schn.

Pfeifferella sp. [J. J. Clarke,

1895].

Hyaloklossia pelseneeri, Leger.
Minchinia sp. [Labbe, 1896].

LIST OF SPOROZOAN HOSTS

339

Balanoglossus kupffcri .

Glandiceps hacksi
Ptychodera clavigera ,

P. sarniensis

ENTEROPNEUSTA.

Hepatic region of Monocystis sp. [Spengel,

gut 1893].

Oesophagus and gut Sporozoon [Spengel, 1893].

Hepatic region of Monocystis sp. [Spengel, 1893].

gut

Oesophagus and Sporozoon [Spengel, 1893].

intestine

A maroecium, punctum .
dona intestinalis
Clavellina producta
Diazona violacea .
Distaplia magnilarva .
Perop/wra annectens

Phallusia mammillata
Salpa aeruginosa .

S. confocderata ; S. vagina
S. maxima .

TDNICATA.

Gut . . . Lankesteriaamaroecii(Gia,vd.).
Stomach and rectum L. ascidiae (Lank.).

Gut

Pleurozyga clavelliiiac (Roll.).
Lankestcria diazonae (Ming.).
Pleurozyga distapliae, Ming.
" Gregarina " sp. [Ritter,

1893].

Pleurozyga phallusiae ( Koll. ).
"Gregarina" ensiformis

[Bargoni, 1894].
"G."flava [Roboz, 1886].
"G." salpae [Frenzel, 1885].

Amphioxus lanccolatus

CEPHALOCHORDA.

Gut epithelium . Lankestcria sp. [Pollard,

1893].

Gill bars and sub- Branchiocystis amphioxi,
cutaneous tissue Burchardt.

PISCES.

Abramis brama . . . Gills

. Gall-bladder .

Acanthias acanthias ( = A. Gut

vulgaris)

,, „ Gall-bladder.

Acerina cernua . . . Gut

,, ,, . . . Mesentery

, Muscles

. . Ovary .
,, Gills .

A. mirandella . . . Ovary .

Alosa, see Clupeapilchardus.

Amiurus melas . . . Base of dorsal fins ,

Ammodytes tobianus . . Gut

Myxobolus exiguus, Thdl.
Spfuierospora masomca, Cohn.
Goussia lucida (Labbe).

Chloromyxum leydigi, Ming.
Hentieguya tenuis, Vaney &

Conte.
Pleistophora acerinae, Van. &

Conte.
Leptotheca perlata (Gurley) ;

Henneguya creplini

(Gurley).
Rliabdospora thdlohani, La-

guesse.
Myxobolus oviformis, Gurley ;

M. obesus, Gurley.
Pleistophora mirandellae,

Vaney et Conte.

Henneguya linearis (Gurley).
Rhabdospora thelohani, La-

guesse ; Goussia bige-

mina, Labbe.

340

LIST OF SPOROZOAN HOSTS

Anguilla vulgaris
Aphredoderus sayanus
Atherina he.psetus
Barbus barbus (—B.fluvia-
tilis)

Belone acus and B. belone

[=B. vulgaris']
Blennius montagui

B. ocellatus
B. pholis

Box bo'ops ; B. salpa
Callionymus lyra

Caranx trachurus ;

Trachurus.
Carassius carassius
Cepola rubescens

Chondrostoma nasus

Clupea harengus
C. pilchardus

Cobitis fossilis ; see Misgur

nus.
Conger conger

Coregonus lavaretus [ = C.
fera]

Gut

Muscles
Gall-bladder .
Gills

Goiissia variabilis (The"l.).
Henneguya monura (Gurley).
Leptotheca hepseti, Thel.
Myxobolus miillcri, Biitsch.

Spleen, intestine, M. pfeifferi, Thel.

ovary
Gall-bladder . . Myxidium sphaericum, Thel.

Blood .

Gall-bladder .
Kidney tubules
Gall-bladder .
Blood .

Muscles
Gall-bladder .

»
Muscles

Body-cavity
Gall-bladder ,
Liver .
Tongue .

Liver .

Te's'tis .
Gall-bladder ,
Heart .

Gall-bladder .
Gill epithelium

Haemogregarina bigemina, L.

& M.

Sphaeromyxa incurvata, Don.
Sphaerospora divergens, Thel.
Myxidium incurvatum, Thel.
Haemogregarina bigemina, L.

&M.

Pleistophora typicalis, Gurley.
Ceratomyxa pallida, Thel.
Myxidium incurvatum, Thel.
Chloromyxum quadratum,

Thel. ; Glugeadestruens,

Thel.

Myxobolus sp. [Gurley, 1894].
Sphaeromyxa balbianii, Thel.
Glugea ovoidea, Thel.
' ' Psorosperms " [Leydig,

1851].
Goussia clupearum (Thel.).

i» »

Coccidium sardinae, Thel.
Ceratomyxa truncata, Thel.
Glugea cordis, Thel.

" Myxosporidium " congri

[Perugia, 1891].
Myxobolus sphaeralis, Gurley.

Gills .

Coris giofredi . . . Gall-bladder .

C. julis .... Muscles

„ .... Gall-bladder.

,, . . . . Liver .

Coitus bubalis . . . Gut

,, ... Muscles

C. scorpius .... ,,

Crenilabrus mediterraneus Gall-bladder .

and C. pavo
C. melops .

Intermuscular tissue M. zschokkei, Gurley.

,, Henneguya kolesnikovi (Gur-

ley).

. H. sp. [Claparede, 1874].
. Glugea marionis, The*!.
, Chloromyxum quadratum,

Thel.

, Glugea marionis, Thel.
, G. depressa, Thel.
, Goussia variabilis (Thel.).
Pleistophora typicalis, Gurley.

Ceratomyxa inaequalis, Don.

C. sp. .

Gut . . . Goussia variabilis (The"!.).

Kidney tubules . Sphaerospora divergens, Thel.

Gall-bladder . . Ceratomyxa arcuata, Thel.

Eye . . . Myxobolus miilleri, Biitsch.

Body-cavity . . Glugea gigantea, Thel.

Gut, liver, spleen, Rhabdospora thelohani, La-
and pancreas guesse.

LIST OF SPOROZOAN HOSTS

Cyprinodon variegatus
Cyprinus carpio .

Engraulis encrasicholus
Entelurus aequoreus ; see

Nerophis.
Erimyzon sucetta

» >> •

Esox lucius

Subcutaneous con- Myxobolus lintoni, Gurley.

nective tissue

Kidney tubules, M. cyprini, Dofl. ; Hoferellus
gills cyprini (Don.) ; Myxo-

bolus dispar, The!.
Gut . . . Rhabdospora the'lohani, La-

guesse.
Liver . . . Ooussia clupearum (The!.).

Flesus passer
Gadus pollachius
Galeus galeus

Gasterosteus aculeatus
>> »

G. a. and G. pungitius

G. pungitius
G. sp.

Girardinus sp. .

Gobio gobio ( = G. fluviatilis')

Gobius albus ; see Latrun-

culus.
G. fluviatilis

G. minutus

G. paganellus ( = G. bicolor)
Hippocampus brevirostris .

Hybognathus nuchalis .
Julis giofredi ; see Coris.

Gills .
Skin .

Urinary bladder .
Gills, muscles, eye

Eggs .
Gills .

Intracellular tissue
of eye-muscles,
etc.

Gut

Connective tissue
of eye-muscles
Gall-bladder .

Liver .
Skin tumours

Kidney tubules and
connective tis-
sue of ovary

Kidney tubules
and ovary

Subcutaneous con-
nective tissue,
cornea, ovary

Muscles

Kidney tubules

Skin, musculature,
wall of intes-
tine

Gut

Fins, gills, kidney,
spleen

Myxobolus globosus, Gurley.
M. oblongus, Gurley.
Myxidium lieberkiihnii, Biits.
Henneguya psorospermica,

Thel.

If. p. oviperda (Cohn).
H. p. lobosa (Cohn) ; H. p.

anura (Cohn).
H. schizura (Gurley).

Glugea stephani (Hagen-

miiller).
G. punctifera, Thel.

Ceratomyxa sphaerulosa,

Thel.

Coccidium gastcrostei, Thel.
" Myxosporidian " [G. W.

Miiller, 1895].
Sphaerospora elegans, Th^l.

Henneguya media, Thel. ; H.

brevis, Thel.
Glugea anomala, Monz. ( = (?.

microspora, Thel.).

Pleistophora typicalis,GuT\ej.
Rhabdospora the'lohani, La-

guesse.
Glugea girardini (Lutz &

Splendore).

Coccidium metchnikovi,

Laveran.
Myxobolus oviformis, Thel.

Body -cavity . . " Psorosperms " [Leydig,

1851].
Connective tissue . Glugea anomala, Monz.

( = G. microspora, The"!.)

Liver . . . Goussia varialilis, Labbe.
Gut ... ,, „ (Thel.).

Bile-ducts . . Sphaeromyxa sabrazesi, L. &

M.

Connective tissue Henneguya macrura (Gurley).
of lower jaw

342

LIST OF SPOROZOAN HOSTS

Labeo niloticus .

Labriis festivus .
L. turdus .
Lamna cornubica

Latrunculus albus

Lepadogaster gouani .
Leptocephalus conger ; see

Conger.
Leuciscus cephalus

» » •

L. erythrophthalmus .

L. funduloides .
L. phoxinus

Myxobolus unicapsulatus,

Gurley.

Liver . . . Goussia thelohani, Labbe.
Gall-bladder . . Ceratomyxa linospora, Dofl.
Gut . . . Pfeifferella gigantea (Labbe) ;

Coccidium giganleum,

Labbe.
Subcutaneous con- Olugea anomala, Monz. ( = G.

nective tissue microspora, Thel.).

Gut . . . Goussia variabilis (Thel.).

L. rutilus .

» ...

» ...

» ...

Lophius budegassa
L. piscatorius

» •

Lota lota ( = L. vulgaris)

Lucioperca lucioperca ( = L.
sandra)

Merluccius merluccius '(•-
M. vulgaris)

Misgurnus fossilis
Motella maculata

M. tricirrata

Mugil auratus .
M. chelo

Gall-bladder. . Chloromyxumfiuviatile,rY\\G\.
Fins and gulls . Myxobolus miilleri, Biitsch.
Gills . . . Myxosoma dujardini, Thel.
Muscles and spleen Myxobolus dispar, Thel.
Scales . . . M. transovalis, Gurley.
Ovary . . . Rhabdospora thelohani, La-

guesse.
Kidney and ovary. Afyxidium histophihim,The\. ;

Myxobolus miilleri, Biits.
..; Glugea sp. [L. Pfeiffer, 1895].

Gills . . . Myxosoma dujardini, The!.
Operculum and Myxobolus cycloides, Gurley.

pseudobranch

Gills . . . Henneguya sp. [Borne, 1886].
Heart . . . " Psorosperms " [Leydig,

1851].
Gall-bladder . . Ceratomyxa appcndiculata,

Thel.

Urinary bladder . Myxoj)roteusambigut(s(Tlie].).
Spinal ganglia and Glugea lophii, Dofl.

cranial nerves

Urinary bladder . Myxidium lieberkuhnii,

Biitsch. ; Chloromyxum
mucronatum, Gurley.

Kidney . . . Myxobolus dipleurus, Gurley.
Gill epithelium . M. sp. [J. Miiller, 1841].

Gills . . . "Psorosperms" [Heckel &

Kner, 1858].

Gall-bladder . . Leptotheca elongafa, Thel. ;
Ceratomyxa globulifera,
Thel.

Myxobolus merluccii (Peru-
gia)-

Kidney . . . M. piriformis, The"!.
Gut and pyloric Crystallospora crystalloides

coeca (Thel.).

. Gall-bladder . . Sphaeromyxa balbianii, Thel.

. Gut and pyloric Crystallospora crystalloides

coeca (Thel.) ; Goiissia motellae

(Labbe).

. Gall-bladder . . Ceratomyxa arcuata, Thel. ;
Sphaeromyxa balbianii,
Thel.

. Liver . . . Glugea ovoidea, Thel.
M. capita; Stomach, pyloric Myxobolus exiguus, Thel.
coeca, gills,
spleen, kidney

LIST OF SPOROZOAN HOSTS

343

Mugil sp. .
Afustelus eanis

M. laevis
Ncrophis aequoreus

Notrojns megalops
Pagellus centrodontus

Perca fl'uviatilis .

Phoxinus funduloides and

P. laevis ; see Leuciscus.
Phycis phycis ( = P. mcdi- Gall-bladder.

terranea)
Pimelodus blochi ; see Pira-

mutana.

P. clarias ; see Synodontis.
P. sebae .... Gills
Piramutana blochi

Glomeruli of kid- Sphuerospora rostrata, Thel.

ney

Gut . . . Goussia lucida (Labbe).
Gall-bladder . . Ceratomyxa sphaerulosa,
Thel.

»»-•-• » »

,, . . Myxidium incurvatum, Thel.
Muscles . . Ghloromyxum quadratum,

Thel.
Connective tissue Glugea acuta, Thel.

of dorsal fin

Skin . . . Myxosporidian[Linton, 1891],
Gall-bladder . . Ceratomyxa arcuata, var.

typica, Thel.
Gut . . . Rhabdospora thelohani,

Laguesse.
Gills . . . Henneguya psorospermica-

(Cohn) ; Myxobolus tex-

tus, Colin.

Leptotheca
Labbe.

polymorpha,

Platystoma faseiatum .
Pleiironectes jilatessa .

Pseudoplatystoma ; see Platy-
stoma.

Raia alba ; see R. undulata.
R. asterias .
R. batis ; It. clavata .
H. mosaica .

R. punctata
Jl. undulata

Rhamdia sebae ; see Pimelo-
dus.

Rhina squatina .
Salvelinus fontinalis .

Scardinius erythrophthal-

mus ; see Leuciscus.
Scomber scombrus

Scorpaenn porcus
S. scrofa

S. sp.' .'.'.'.
Scy Ilium canicula
S. catulus ; see S. stellare
S. stellare .

Gill-chamber
Gut

Gall-bladder .
Blood .

Gall-bladder .

Henneguya linearis (Gurley).

Myxobolus inaequalis, Gur-
ley.

Henneguya linearis (Gurley).

"Sporozoon" [Johnstone,
1901] = Glugea sp. [fide
H. M. Woodcock inM.S.].

Myxidium giganteum, Dofl.
Chloromyxum leydigi, Ming.
Haemogregarina delagei, L.
&M.

» »

Chloromyxum leydigi, Ming.

,, . Chloromyxum leydigi, Ming.

Blood, muscles, gut, Lymphosporidium truttae,
and lymph . Calkins.

Gut

Gall-bladder .
Kidney tubules
Gills .
Gall-bladder .

Gut

Goussia clupearum (Thel. ).
Leptotheca parva, Thel.
L. renicola, Thel.
" Psorospernis " [Borne, 1886].
Ceratomyxa arcuata, var.
scorpaenarum, Labbe.

Myxidium incurvatum, Thel.
Leptotheca agilis (The"l.).
Chloromyxum leydigi, Ming.

Goussia lucida (Labbe).

344

LIST OF SPOROZOAN HOSTS

Solea vulgaris

Sphyraena sphyruena ( = S.

vulgaris)

Spinax spinax ( = S. vulgaris)
Squalius cephalus ; see Leu-

ciscus
Squatina angelus ; see Rhino,

squatina .
Stizostethium lucioperca ; see

Lucioperca.
Syngnathus acus

Synodontis schall

Thymallus thymallus (= T.

vulgaris)
Tinea tinea ( = T. fluviatilis

and T. vulgaris)

Torpedo narce ; T. torpedo

( = T. marmorata)
Trachinus draco .

Trachurus trachurus .

Blood . . . Haemogregarina simondi, L.

& M.
Gut . . . " Cretya " neapolitana, Ming.

Gall-bladder. . Chloromyxum leydigi, Ming.

Muscles

Connective tissue
of dorsal fin .
Gills .
Head .
Neurilemma (?)

Gill epithelium

Liver, kidney,
spleen

Gills, spleen, kidney

Swim-bladder, gills,
kidney, spleen,
liver, cornea

Gall-bladder .

Myxidium incurvatum, The"!.
Chloromyxum quadratum,

Thel.
Glugea acuta, Thel.

Myxobolusinaequalis,GuT\ey.
Henneguya strongylura, Gurl.
Myxobolus pfeifferi, Thel.

Rhdbdospora thelohani,

Laguesse.
Goussia minuta (Thel.).

Myxobolus piriformis, Thel.
M. ellipsoides, Thel.

Liver .
Muscles

Trygon pastinaca ( = T. mil- Gall-bladder .
garis)

Batrachoseps attenuatus
Bufo lentiginosus

B. marinus ( = B. agua)

B. sp

Cystignathus oeellatus ; see

Leptodactylus.
Hyla arborea ( = H. viridis)
Leptodactylus oeellatus
Molge cristata

M. marmorata ; M. palmata

M. vulgaris ; M. sp.
Rana esculenta .

AMPHIBIA.

Erythrocytes
Kidney .

Gall-bladder .
Gut

Blood .

Gall-bladder

Gut

Gall-bladder
•Gut

Chloromyxum leydigi, Ming.

Ceratomyxa reticularis, The"l. ;

Myxidium incurvatum,

Thel.

Goussia cruciata (Thel.).
Chloromyxum quadratum

Thel.
Leptothecaagilis, Thelohan ;

Chloromyxum leydigi,

Ming.

Haemapium riedyi, Eisen.
Leptotheca ohlmacheri (Gur-

ley).

Cystodiscus immersus, Lutz.
Diplospora sp. [Grassi, 1881].

. Cytamoeba sp. [Grassi, 1882].

. Cystodiscus immersus, Lutz.

. Coccidium proprium (Aim.
Schn.).

. Chloromyxum caudatum,
Thel.

. Coccidium proprium (Aim.
Schn.).

. C. ranarum (Labbe") (incl.
Karyophagus ranarum,
Labbe\ and Molybdis
entzi, Pach. ?) ; Para-
coccidium prewti, L. & M.

LIST OF SPOROZOAN HOSTS

345

Rana esculenta

R. temporaria

Salamandra salamandra Gut
( = S. maculata)

Triton spp. ; see Molge.

Kidney . . . Diplospora lieberkiihni

(Labbe) ; Leptotheca ohl-
macheri (Gurley) ; L.
ranae, Thel.

Renal epithelium . Karyamoeba renis, G. Tos.

Blood, spleen, bone- Lankesterella ranarum, Lank.,
marrow, etc. and L. monilis, Labbe

(incl. Haemogregarina
magna, Gr. et Fel. ; Lave-
rania ranarum, Kruse ;
Dactylosoma splendens,
Labbe ; and Cytamoeba
bacterifera, Labbe).
. Diplospora lieberkiihni

(Labbe) ; Leptotheca ohl-
macheri (Gurley) ; L.
ranae, Thel.
. Pleistophora danilewskyi

(L. Pfr.).
. " Myxosporidian " [G. W.

Miiller, 1895].

. Coccidium salamandrae

(Steinhaus) (incl. Karyo-
phagus salamandrae,
Steinh.).

Spermatocyte nuclei Micrococcidium caryolyticum
[Driiner, 1894].

Kidney .

Muscles
Skin

A lligutor mississipiensis

Ancistrodon piscivorus
Anguis fragilis .
Eothrops sp.

Bungarus fasciatus
Chalcides tridactylus .

Chameleo vulgar is
Cistudo europaea ; see Emys.
Clemmys elegans . . Blood
Coelopeltis lacertina . . Gut

Coluber aesculapii . . Blood

C. carbonarius ; see Zamenis

gemonensis.
C. corais . . . . ,,

Coronella austriaca . . Gut
C. sp. . ,,

Crocodilus frontatus . . Blood

C. sp Gut

Crotalus confluentus . . Blood
C. sp „

REPTILIA.
Blood .

Gut
Blood

Muscles
Gut

Haemogregarina crocodili-

norum, Bb'rner.
H. mocassini, Lav.
Coccidium railleti, Leger.
Drepanidium serpentium,

Lutz.
Haemogregarina bungari

(Billet).
(?) Pleistophora danilewskyi

(L. Pfr.).
Diplospora mesnili, Sergent.

Haemogregarina labbe"i, Born.
Diplospora laverani, Hagen-

miiller.
Haemogregarina sp. [Borner,

1901].

Drepanidium serpentium,

Lutz.

Coccidium sp. [Grassi, 1888],
Isospora sp. [Grassi, 1881].
Haemogregarina crocodili-

norum, Borner.
Coccidium sp. [Solger &

Gabriel, 1876].
Haemogregarina crotali, Lav.
Drepanidium serpentium,

Lutz.

346

LIST OF SPOROZOAN HOSTS

Cryptopus granosus ; see

Emyda.

Damonia reevesii . . Gut (rectum)
. Blood .

Drynwbius biforsatus .

Emyda granosa .
Emys orbicularis (=E. lu-
taria and E. europaca

E. tecta ; see Kachuga.
Eunectes murinus

Gavialis gangeticus

Gongylus ocellatus
Herpetodryas carinata
Kachuga tectum .

Lacerta agilis ; L. muralis

L. muralis ....
L. occllata; L. viridis; L. sp.

i. sp. ....

Naja tripudians .
Philodryas olfersii

Platemys sp.

Platydactylus maui-itani-

cus; see Tarentola.
Python reticulatus

Rhadinaea merremii .

Seps chalcides ; see Chaleides.
Spilotes pullatus
Tarentola mauritanica

Testudo ibera
T. marginata
Trionyx indicus .
T. sp.

Gut

Blood .

Kidney .

Muscles

Blood
Spleen
Blood

Gut
Blood

Ovary .
Blood .

Gut (and kidney ?)
Muscles

Ova
Blood .

Muscular fibres
Blood .

Coccidium mitrarium, L. & M.
Haemogregarina stepanovi-

ana, L. & M.
H. rara, L. & M.
Drepnnidium serpentium,,

Lutz.

Coccidium Ugeri, Simond.
C. delagei, Labbe.

Haemogregarina stepanovi,

Danil.

Myxidiujn danileivski, Lav.
Pleistophora danileivskyi

(L. Pfr.).

Drepanidium scrpentium,

Lutz.
Coccidium kermoganti,

Simond.
Haemogregarina hankini,

Simond.

Diplospora camillerii, Hagen.
Drepanidium serpentium.
Haemogregarina mesnili,

Simond.
H. lacazei (Labbe) ; Karyoly-

sus lacertarum (Danil.).
Coccidium lacertae (Ming.).
Karyolysus lacertarum

(Danil.).

Coccidium sp. [Eimer, 1870].
(?) Pleistophora danilewskyi,

(L. Pfr.).
" Myxosporidian " [Mingaz-

zini, 1892].

Haemogregarina nnjae, Lav.
Drepanidium serpentium,

Lutz.
Haemogregarina labbe^i, Born.

H. pythonis (Billet) ; H.

colubri, Borner.
Drepanidium serpentium,

Lutz.

Sarcocystis platydactyli,

Bertram.
Haemogregarina platydactyli,

Billet.
Karyolysus (?) sp. [Popovici,

1901].
Haemogregarina stepanovi.

Danil.
Haemamoeba metchnikovi,

Simond.
Haemogregarina stepanovi,

Danil.

LIST OF SPOROZOAN HOSTS

347

T. stellatus
Tropidonotus stolatus
Xenodon neuviedii

Zamenis gemonensis
mridiflavus)

Z. hippocrepis

Blood

= Z. Vasa deferentia

Blood

U. billeti, Simond.
H. pythonis, Borner.
Drepanidium serpentium,

Lutz.
Coccidium colubri (Ming.).

Pleistophora heteroica (Monz.).
Haemogregarina zamenis,I^a.v.

AVES.

Acanthis cannabina
Actitis hypoleucus ,

Totanus.
Agelaeus phoeniceus

A lauda arvensis .

. Gut
see

. Blood

. Gut

. Blood

Alccdo ispida . . . Gut

Anas boschas ; A. clypeata . Intermuscular con-
nective tissue

A. domestica . . . Gut

Anser domesticus . • ,,

,, ,, . . . Kidney tubules
Apus apus ; see Cypselus a.

Arenaria interpres . . Gut

Asio otus .... Blood .

Athene nod.ua; see Carine

Bubo virg inianus ; B. sp. . ,,

Budytes flav us . . . Gut

Buteo butco (-B. vulgaris) Blood .

Calidris arenaria . . Gut
Cannabina linota ; see

Acanthis c.

Carduelis carduelis ( = C. ,,

elegant)

Carine noctua . . . Blood

Charadrius alexandrinus ; Gut

C. dubius ; C. pluvialis

Chelidonaria urbica ( — Gheli- , ,

don u. )

Chloris chloris . . • ,,

Chrysomitris spinus . . ,,

Circus aeruginosus . . Blood

Clivicola riparia . . Gut
Coccothraustes coccothraustes ,,
( = 0. vulgaris)

Diplospora lacazei, Labbe.

Halteridium danilev'skyi
(Gr. & Fel.) ; Haemopro-
teus danilewskyi, Kruse.

Coccidium avium (Silv. &
Riv.); Diplospora lacazei,
Labbe.

Halteridium danilewskyi
(Gr. & Fel.) ; Haemo-
proteus danilewskyi,
Kruse.

Diplospora lacazei, Labbe.

Sarcocystis rileyi (Stiles).

Coccidium avium (Silvestr. &
Rivolta).

» 11

C. truncatum, Raill. & Lucet).

C. roscoviense, Labbe.
ffaemoproteus danilewskyi,
Kruse.

Halteridium danilewskyi
(Gr. &Fel.).

Diplospora lacazei, Labbe.

Halteridium danilewskyi
(Gr. & Fel. ) ; Haemopro-
teus danilewskyi, Kruse.

Coccidium roscoviense, Labbe.

C. avium (Labbe) ; Diplospora

lacazei, Labbe.
Halteridium danilewskyi

(Gr. & Fel.).
Coccidium roscoviense, Labbe.

Diplospora lacazei, Labbe.

Hae m oproteus danilewskyi,

Kruse.
Diplospora lacazei, Labbe".

348

LIST OF SPOROZOAN HOSTS

Colaeus monedula

Columba domestica
» »>

C. livia

Coracias garrula
Corvus comix

Blood

Gut
Blood

. Gut
. Blood

C. comix; C. corone . . Gut

C. americanus ; C. corax . Blood

C, frugilegus . . . ,,

Cotyle riparia; see Climcola.

Cuculus canorus . . Gut

Cypselus apus . . • ,,

Dendrocopus minor . • ,,
Emberiza citrinella . • ,,

E. miliaria ( = E. projer) . Blood

Erithacus luscinia ; E. phoe- Gut

nicurus ; E. rubeculus

Falco tinnunculus . . Blood

Fringilla canaria ; see Ser-

inus

F. carduelis ; see Carduelis.
F. coelebs .... Gut
. Blood

F. montifringilla
Galerita cristata .
Gallus domesticus

Garrulus glandarius
Habia ludoviciana

Hirundo rustica .
lynx torquilla
Lanius collurio .
L. excubitor

Gut

Ova

Muscles and con-
nective tissue
Blood .

Intramuscular con-
nective tissue
Gut

Blood

L. minor ; L. senator ( = L. ,,

rufus)

Ligurinus Moris; see Chlori's.
Luscinia vera and L. phoeni-

curus ; see Erithacus.
Meleagris gallopaw . . Gut

Haemoproteus danilewskyi,

Kruse.

Coccidium pfeifferi, Labbe.
Halteridium danilewskyi (Gr.

&Fel.).
Haemoproteus danilewskyi,

Kruse ; Halteridium

danilewskyi (Gv. & Fel.).
Diplospora lacazei, Labbe.
Haemoproteus danilewskyi,

Kruse.

Diplospora lacazei, Labbe".
Halteridium danilewskyi (Gr.

&Fel.).
Haemoproteus danilewskyi,

Kruse.

Diplospora lacazei, Labbe".

Halteridium danilewskyi

(Gr. &Fel.).
Diplospora lacazei, Labbe.

Halteridium danilewskyi
(Gr. & Fel.); Haemo-
proteus danilewskyi,
Kruse.

Diplospora lacazei, Labbe".

Halteridium danilewskyi
(Gr. & Fel.) ; Haemo-
proteus danilewskyi,
Kruse.

Diplospora lacazei, Labbe.

)) J !

Coccidium avium (Silvestr.

& Rivolta).
Coccidium sp. (?) [Podwys-

sozki, 1890].
Sarcocystis sp. [Kiihn, 1865 ;

Stiles, 1894].
Halteridium danilewskyi (Gr.

& Fel.).
Sarcocystis falcatula, Stiles.

Diplospora lacazei, Labbe1.

Haemoproteus danilewskyi,
Kruse.

Coccidium avium (Silv. &
Riv.).

LIST OF SPOROZOAN HOSTS

349

Mflospizafasciata; M. gear- Blood
giana

Milvus migrans

Monedula turrium ; see Col-

aeus m.
Motacilla alba . .Gut

Muscicapa atricapilla . . ,,

Numenius phaeopus . . ,,

Oriolus oriolus ( = 0. gal- ,,

bula)

Otus vulgaris ; see Asio otus.

Padda oryzivora . . . Blood

Pandion haliaetus . . ,,

Parula pitiayumi . . Muscles

,, ,, . . Pectoral muscles

(1)Paruscaeruleus(=P. cya- Gut

neus)

P. major .... Blood .

Passer domesticus

P. hispaniolensis ; P. mon-

tanus
P. montanus

Gut
Blood

Pavo cristatus
Pernis apivorus .

. Gut
. Blood

Phalacrocorax gracuhis (= Gut

P. cristatus)

Phasianus colchicus ; P. sp. ,,

Pica pica ( = P. caudata) , Blood .

P'icus minor ; see Dendro-

copus m.
Pluvialis apricariua ; see

Charodrius pluvialis.
Pyrrhula europaea (= P. Gut

vulgaris)
Hubecula familiaris ; see

Erithacus r.

Saxicola oenanthe . • »
Serinus canarius . ,,

Setophaga ruticilla . . Muscles
Spatula clypeata ; see Anas.
Strepsilas interpres ; see

Arenaria.
Strix flammca . . . Blood .

Sturnus vulgaris

Gut
Blood

Halteridium danilewskyi
(Gr. & Fel.) ; Haemopro-
teus danilewskyi, Kruse.

Ifaemoproteus danilewskyi
(Kruse).

Diplospora lacazei, Labbe ;

Coccidium roscoviense,

Labb^.

Diplospora lacazei, Labbe.
Coccidium roscoviense, Labbe.
Diplospora lacazei, Labbe".

Halteridium danilewski (Gr.

et Fel.).
Haemoproteus danilewskyi,

Kruse.
Sarcocystissp. [Barrows, 1883].

Diplospora lacazei, Labbe.

"Haemamoeba" sp. [Laveran,

1902].

Diplospora lacazei, Labbe.
Halteridium danilewskyi (Gr.

& Fel.) ; Haemoproteus

danilewskyi, Kruse.
Haemoproteus danilewskyi,

Kruse.
Halteridium danilewskyi (Gr.

&Fel.).
(?) Coccidium avium (Silv. &

Riv.).
Haemoproteus danilewkyi,

Kruse.
Coccidium roscoviense, Labbe.

C. avium (Silv. & Rivolt. ).
Haemoproteus danilewskyi,
Kruse.

Diplospora lacazei, Labbe.

Sarcocystis sp. [Stiles, 1894].

Halteridium danilewskyi (Gr.

et Fl.).

Diplospora lacazei, Labbe.
Halteridium danilewskyi (Gr.

etFel.).

350

LIST OF SPOROZOAN HOSTS

Sylvia atricapilla;S. hortensis
Syrnium aluco

Totanus hypoleucus ; T.
totanus ( = T. calidris)
Tringa alpina ; T. sp.
Turdus merula .

Turtur turtur ( = T. auritus)
Upupa epops

Gut . . . Diplospora lacazei, Labbe.

Blood and bone- HalteridiumdanileuJskyi(Gt.

marrow et Fel.).

Gut . . . Coccidiumroscoviense, Labbe.

Apes .
Bos taurus

Bubalus sp.

Co, nis fami liaris .

Capra hircus

» )>

Cavia cobaya

Cervus capreohis .
Cricetus cricetus .
Equus caballus .

Fells domestica

" ?'

Lepus cuniculus

» >:

!> »

» »

L. timidus .

Macacus sp.
Macropus penicillatus ,
Petrogale.

Connective tissue
Gut

MAMMALIA.

Blood .
Intestine, bladder .

Liver and intestine
Muscles

Blood .

Muscles
Intestine

Lungs .
Muscles
Blood .
Intestine

Muscles
Gut

Muscles
Gut

Kidney .
Intestine

Submucosa of in-
testine

Blood . .
Intestine

Muscles
Intestine
Liver ,

Ovum .

Muscles

Intestine

Muscles

Diplospora lacazei, Labbe.
Sarcocystis sp. [Kiihn, 1865].
Coccidium pfeifferi, Labb6.
Diplospora lacazei, Labbe.

Plasmodium kochi (Laveran).
Coccidium perforans, var.,

Hess & Zschokke.
O. perforans, var., Zurn.
Sarcocystis sp. [Hessling,

185:3].
Piroplasma bigeminum (Sm.

et K. ) = Babesia bo vis

(Babes).

Sarcocystis sp. [Jongb, 1885].
Coccidium bigeminum, var.

canis, Raill. et Lucet.
C. sp. [Lienaux, 1891].
Sarcocystis sp. [Krause, 1 863].
Piroplasma canis ( P. et G. V. ).
Coccidium perforans, var. ,

Hess & Zschokke.
Sarcocystis sp. [Jongh, 1885].
Cyclospora caryolytica,

Schaud.
Sarcocystis sp. [Hessliug,

1853].
Cyclospora caryolytica,

Schaud.
"Eimeria" sp. [Pachinger,

1886].
Coccidium perforans, var. ,

Hess & Zschokke.
Globidium leuckarti [Flesch,

1884] ; Sarcocystis sp.

[Gerlach, 1866].
Piroplasma equi, Laveran.
Coccidium bigetnimim, var.

cati, Raill. et Lucet.
Sarcocystis sp. [Krause, 1863].
Coccidium perforans, Leuck.
C. cuniculi (Riv. ) = C.

oviforme, Leuck, incl.

Pfeifferella princeps

(Labbe).

C. sp. [Pdwyssozky, 1892].
Sarcocystis sp. [Manz, 1867].
Coccidium perforans, Leuck.
Sarcocystis sp. [Hardenberg,

1865].
S. sp. [Ratzel, 1868].

LIST OF SPOROZOAN HOSTS

351

Miniopterus schreibersi . Blood

Mus decumanus . . . Muscles
Mus musculus . . . Intestine

» • •

. Kidney .

,,

. Muscles

M. rattus .
Mustela putorius

. Intestine

M. vulgaris

. Gut

Myotis capaccinii

. Blood .

M. myotis ; see Vespertilio

murinus.
Otaria calif ornica ; see Zalo-

phus.
Ovis aries ....

Petrojale penicillata .

Potamochoerus larvatus
Rhinolophus ferrum - equi-

num
Sus domesticus .

Talpa europaea .
Vespertilio murinus .
Vesperugo sp.
Zalophus californianus
Homo sapiens, Man

. PolycJiromophilus melani-

phorus, Dionisi.
. Sarcocystis sp. [Siebold, 1853].
. Coccidium falciforme (Eimer)

(incl. Eimeria falcifor-

mis (A. Schn.) ; Pfeifferia

sckubergi, Labbe, etc.).
. Klossiella muris, Smith et

Johnston.
. Sarcocystis muris (Blan-

chard).

. S. sp. [Siebold, 1853].
. Coccidium bigeminum, var.

putorii, Raill. et Lucet.
. Cyclospora caryolytica,

Schaud.
. Polychromophilus mclani-

pherus, Dionisi.

Intestine

Muscles and con-
nective tissue
Blood .

Subintestinal con-
nective tissue
Muscles
Intestine

Liver and intestine
Muscles and con-
nective tissue
Gut

Blood .

Muscles

Liver .

Intestine

Pleural cavities
Skin, etc.
Blood .

Muscles
Liver .

Coccidium perforans, var.,

Curtice.
Sarcocystis tcnella, Raill.

Piroplasma ovis ( = Babe.sia

oms, Starcovici).
Sarcocystis mucosa (Blan-

chard).

S. sp. [Pagenstecher, 1865].
Coccidium viride, Labbe.

C. perforans, var., Rivolta.
Sarcocystis miescheriana

(Kiihn).
' Cyclospora caryolytica,

Schaud.
Polychromophilus murinus,

Dionisi.
Achromaticus vesperuginus,

Dionisi.
Sarcocystis hueti (Blanchard).

(?) Coccidium cuniculi (Riv.).

C. perforans, var. [Kjellberg
I860].

C. bigeminum, Stiles.

"Eimeria" hominis, Blan-
chard.

Coccidioides immitis, Rixf. et
Gilchr.

Laverania malariae, Gr. et
Fel. ; Plasmodium

malariae (Laveran) ;
Plasmodium vivax (Gr.
et Fel.).

Sarcocystis lindemanni (Riv. ).

S. immitis (Blanchard).

352 LITERATURE OF THE SPOROZOA

LITERATURE OF THE SPOKOZOA.

The following list of references is by no means intended to be a complete
bibliography of the Sporozoa, but merely to be a guide to the literature of the
group, especially to the recent advances in knowledge. Hence, of the less recent
works, only comprehensive treatises are cited, in which more or less exhaustive
bibliographical references will be found. Butschli [1] gives a complete biblio-
graphy up to 1882, and Hagenmiiller [3] is a valuable and exhaustive summary
of Sporozoan literature up to 1898 inclusive. Bibliographies more or less complete
are to be found in Delage and Hfrouard [2], Lahbe [4], and Lilhe [5], and full
references to the recent literature of malarial parasites are given by Schaudinn
[94a], References to current literature will be found in the Zoological Record or
in the Bibliographic/, Zoologica published with the Zoologischer Anzeiger.

I. Works dealing with Sporozoa generally.

1. Butschli, 0. Sporozoa, in Bronn's Klassen und Ordnungen des Thierreichs,

I. (Protozoa), Abth. i. pp. 479-616, pis. xxxiii.-xxxviii. (1882).

2. Delage, Y., and Herouard, E. Sporozoaires in Traite de Zoologie concrete,

I. (Protozoa), pp. 254-302, figs. 401-467 (1896).

2a. Dqflein, F. Die Protozoen als Parasiten und Krankheitserreger, etc. Jena
(Gustav Fischer), pp. xiii. +274, 1 p. hi., 220 figs. (1901).

3. Hagenmiiller, P. Bibliotheca Sporozoologica. Ann. Mus. Hist. Nat.

Marseille (2), Bulletin, t. i. livr. 2; also separate publ., Moullot fils
aine", Marseilles, 4to, 233 pp. (1899). [Complete bibliography of works
relating to Sporozoa published previously to 1st Jan. 1899.]

4. Labbe", A. Sporozoa, in Das Thierreich, Lief. 5. Berlin (Friedliinder) pp.

xx. +180, 196 figs. (1899).

5. Lilhe, M. Ergebnisse der neueren Sporozoenforschung. Jena (Gustav Fischer),

pp. iv. +100, 35 figs. (1900).

6. Mesnil, E. Essai sur la classification et 1'origine des Sporozoaires. Soc.

Biol. Paris, vol. jubil. 1899, pp. 258-274.

7. Wasielewski, V. Sporozoenkunde. Jena (Gustav Fischer), 1896, 162 pp.

Ill figs.

II. Gregarinida.

8. Caullery, M., et Mesnil, F. Sur une Gregarine . . . presentant . . . une

phase de multiplication asporulee. C. R. Ac. Sci. Paris, cxxvi. 3, p. 262

(1898).
8a. et Sur 1'evolution d'un groupe de Gregarines, etc. [Selenidium].

C. R. Soc. Biol. Paris, (11), i. [li.] pp. 7 and 8 (1899).
8&. et Sur quelques parasites internes des Annelides [Selenidium

and Siedleckia]. Miscellanees Biol. dediees au A. Giard (Trav. stat. zool.

Wimereux, ix.), pp. 80-99, pi. ix. (1899).

9. et Sur une mode particuliere de division nucleaire chez les

Gregarines. Arch. Anat. Microsc. iii. 2/3, pp. 146-167 (1900).

10. et Le parasitisme intracellulaire ... des Gregarines. C. R.

Soc. Biol. Paris, liii. 4, pp. 84-87 ; also C. R. Ac. Sci. Paris, cxxxii. p. 220
(1901).

11. Cecconi, J. De la Sporulation de la " Monocystis agilis," Stein. Arch. Anat.

Microsc. v. 1, pp. 122-140, 1 pi.

LITERATURE OF THE SPOROZOA 353

12. Crawley, H. The Progressive Movement of Gregarines. P. Ac. Nat. Sci.

Philadelphia, 1902, pp. 4-20, pis. i., ii.

13. Cudnot, L. Recherches sur Involution et la conjugaison des Gregarines.

Arch. Biol. xvii. 4, pp. 581-652, pis. xviii.-xxi. (1901).

14. Johansen, H. Actinocephahis goronowitschii, etc. Zool. Anz. xvii. pp.

140-145, 4 figs. (1894).

15. Labbd, A., et Racovitza, E. G. Pterospora maldaneorum n.g., n.sp. . . .

parasite des Maldaniens. Bull. Soc. Zool. France, xxii. pp. 92-97, 4 figs.
(1897).

16. Laveran, A., et Mesnil, F. Sur quelques particularity de Involution d'une

Gregarine, etc. C. R. Soc. Biol. Paris, Hi. 21, pp. 554-557, 9 figs. (1900).

17. Lfger, L. Recherches sur les Gregarines. Tablettes Zoologiques, iii. 1, 2,

pp. 1-182, pis. i.-xxii. (1892).

18. Contribution a la connaissance des Sporozoaires. . . . Etude sur

le Lithocystis schneideri. Bull. Sci. France Belgique, xxx. 1, pp. 240-264,
3 pis. (1897).

19. Sur les Gregarines des Dipteres, etc. [Stylocystis], Ann. Soc. Entom.

France, Ixviii. 3, pp. 526-533, 2 figs. (1900).

20. Sur un nouveau Sporozoaire des larves des Dipteres [Schizocystis],

C. R. Soc. Biol. Paris, Iii. p. 868 ; also C. R. Ac. Sci. Paris, cxxxi. 18, p.
722 (1900).

21. La reproduction sexue"e chez les Ophryocystis. C. R. Soc. Biol. Paris,

Hi. pp. 927-930 ; also C. R. Ac. Sci. Paris, cxxxi. 19, p. 761 (1900).

22. Sur une nouvelle Gregarine, etc. [Aggregata coelomica], C." R. Ac.

Sci. Paris, cxxxii. 22, p. 1343 (1901).

23. Note sur le deVeloppement des elements sexuels et la fecondation chez

le Stylorhynchus longicollis, F. St. Arch. Zool. Exp. et Ge"n., Notes et
Revue, (3), x. 4, 5, pp. Ixiv.-lxxiv. 11 figs. (1902).

24. Liger, L., et Duboscq, 0. Les elements sexuels . . . chez les Pterocephalus.

C. R. Ac. Sci. Paris, cxxxiv. 20, pp. 1148, 1149 (1902).

25. Lfyer, L., et Hagenmuller, P. Sur la morphologie . . . de V Ophryocystis

schneideri n.sp. Arch. Zool. Exp. et Gen., Notes et Revue, (3), viii.
vi. pp. xl.-xlv. 2 figs. (1900).

25a. Prowazek, S. Zur Entwicklung der Gregarinen. Arch. f. Protistenkunde,
I. pp. 297-305, pi. ix. (1902).

26. SchewiaTco/, W. Ueber die Ursache der fortschreitenden Bewegung der

Gregarinen. Zeitschr. f. wiss. Zool. Iviii. pp. 340-354, pis. xx., xxi.
(1894).

27. Siedlecki, M. 0 rozwoju plciowym gregariny : Monocystis ascidiae, R. Lank.

(Ueber die geschlechtliche Vermehrung der Monocystis ascidiae, R. Lank. )
Bull. Int. Ac. Sci. Cracovie, Dec. 1899, pp. 515-537, pis. L, ii. (1900).

28. Contribution a 1'etude des changements cellulaires provoques par les

Gregarines. Arch. Anat. Microsc. iv. 1, pp. 87-100, 9 figs. (1901).

29. Walters, M. Die Conjugation . . . bei Gregarinen. Arch. f. mikr. Anat.

xxxvii. pp. 99-138, pis. v.-viii. (1891).

III. Coccidiidea.

30. Blanchard, R. Les Coccidies et leur r61e pathogene. Causeries Sci. Soc.

Zool. France, i. 5, pp. 133-172, 12 figs. (1900).

31. Bonnet- Eymard, G. Sur 1'evolution de VEimeria nova, Schneider. C. R.

Soc. Biol. Paris, Hi. 24, pp. 659-661 (1900).

23

354 LITERA TURE OF THE SPOROZOA

32. Cu&iot, L. Ltgerella testiculi n. sp. etc. Arch. Zool. Exp. et Ge"n., Notes et

Revue, (3), x. 4, 5, pp. xlix.-liii. 6 figs. (1902).

33. Dormoy, P. Apercu sur les modifications de la cellule intraparasitee, etc.

Bull. Soc. Sci. Nancy, (3), ii. 2, pp. 68-72 (1901).

34. LaVbi, A. Recherches zoologiques, cytologiques et biologiques sur les Coc-

cidies. Arch. Zool. Exp. et Ge"n. (3), iv. 3, 4, pp. 517-654, 3 pis. (1897).

35. Laveran, A. Au sujet de Coccidium metchnikovi et . . . Myxdbolus

oviformis. C. R. Soc. Biol. Paris, (10), v. [1.] pp. 1038-1041, 4 figs. (1898).

36. Sur les modes de reproduction d'Klossia helicina, Schneider. T.c.

pp. 1083-1086 (1898).

37. Sur les modes de reproduction d'Isospora lacazei. T.c. pp. 1139-1142

(1898).

38. Au sujet des alterations cellulaires produites par les Coccidies. Op.

cit. lii. p. 378 (1900).

39. Laveran, A., et Mesnil, F. Sur deux Coccidies intestinales de la " Rana

esculenta." Op. cit. liv. pp. 857-860, 9 figs. (1902).

40. et Sur la Coccidie trouve"e dans le rein de la Eaiia esculenta, etc.

C. R. Ac. Sci. Paris, cxxxv. pp. 82-87, 10 figs. (1902).

40a. et Sur quelques Protozoaires parasites d'une Tortue, etc. T.c.

pp. 609-614, 14 figs. (1902).

41. Liger, L. Sur la presence de Coccidies chez les Mollusques Lamellibranches.

C. R. Soc. Biol. Paris, (10), iv. [xlix.] pp. 987, 988 (1897).

42. Echinospora labbei n.g., n.sp. etc. T.c. pp. 1082-1084 (1897).

43. Sur une nouvelle Coccidie a microgametes cilies [Echinospora labbei

and E. ventricosd\. C. R. Ac. Sci. Paris, cxxvii. pp. 418-420 (1898).

44. Sur la morphologic et le developpement des microgametes des Coccidies.

Arch. Zool. Exp. et Ge"n., Notes et Revue, (3), vi. (1898).

45. Essai sur la Classification des Coccidies, etc. Ann. Mus. Nat. Hist.

Marseille, (2), Bull. i. 1, pp. 71-123, 4 pis. (1898).

46. Sur la presence d'une Coccidie crelomique chez Olocrates abbreviate.

Arch. Zool. Exp. et Gen., Notes et Revue, (3), viii. 1, pp. i.-iii. (1900).

47. Sur le genre Eimeria. C. R. Soc. Biol. Paris, lii. pp. 575, 576 (1900).

48. Le genre Eimeria et la classification des Coccidies. T.c. pp. 576, 577

(1900).

48a. Luke, M. Ueber Geltung und Bedeutung der Gattungsnamen Eimeria
und Coccidium. C. B. Bakt. Parasitenkunde, Abth. i. (Orig.) xxxi.
pp. 771, 772 (1902).

49. Mesnil, F. Sur la conservation du nom generique Eimeria, etc. T.c. pp.

603, 604 (1900).

50. Perez, C. Sur une Coccidie nouvelle (Adelea mesnili n.sp.), etc. Op. cit.

(11), i. [li.] pp. 694-696 (1899).

51. Schaudinn, F. Untersuchungen iiber den Generationswechsel bei Coccidien.

Zool. Jahrbiicher, Abth. f. Anat. xiii. 2, pp. 197-292, 4 pis. (1900).
51 a. Studien iiber Krankheitserregende Protozoen — I. Cydospora caryo-

lytica, .Schaud. , etc. Arbeiten a. d. Kaiserl. Gesundheitsamte, Berlin,

xviii. 3, pp. 378-416, pis. xii. and xiii., 1 text-fig. (1902).
516. Sergent, E. Sur une Coccidie nouvelle, etc. \_Diplospora mesnili n.sp.].

C. R. Soc. Biol. Paris, liv. pp. 1260, 1261 (1902).

52. Siedlecki, M. Reproduction sexuee . . . de la Coccidie de la Seiche, etc.

[Benedenia\. C. R. Soc. Biol. Paris, (10), v. [1.] pp. 540-543, 6 figs.
(1898).

LITERATURE OF THE SPOROZOA 355

53. Siedlecki, M. Reproduction sexuee . . . chez . . . Coccidium proprium,

Schn. T.c. pp. 664-666 (1898).

54. Etude cytologique . . . de la Coccidie de la Seiche, etc. Ann. Inst.

Pasteur, xii. pp. 799-836, 3 pis. (1898).

55. Etude cytologique . . . de Adelea ovata, Schneider. Op. eit. xiii.

pp. 169-192, pis. i.-iii. (1899).

55a. Cycle eVolutif de la Caryotropha mesnilii, etc. Bull. Ac. Sci.

Cracovie, 1902, pp. 561-568, 5 text-figs.

56. Simond, P. L. Note sur le dimorphisme eVoluti'f de . . . Karyophagus

salamandrae, Steinhaus. C. R. Soc. Biol. Paris, (10), iii. [xlviii.] pp.
1061-1063 (1896).

67. Smith, T. , and Johnston, H. P. On a Coccidium (Klossiella muris gen. et
spec. nov. ) parasitic in the Renal Epithelium of the Mouse. Journ. Exp.
Medicine, vi. 3, pp. 303-316, pis. xxi.-xxiii. (1902).

58. Stiles, C. W. Eimeria stiedae (Lindemann, 1865), correct name for the

Hepatic Coccidia of Rabbits. U.S. Dep. Agriculture, Bureau Animal
Industry, Bulletin xxv. pp. 18, 19 (1902).

59. Eimeriella, New Genus of Coccidia. L.c.

60. Voirin, V. Zur Morphologic und Biologic einiger Coccidienformen, etc.

Zool. Jahrb., Abth. f. Anat. xiv. 1, pp. 61-106, pi. v. (1900).

IV. Haemosporidia.

61. Argutinsky, P. Malariastudien. I. Arch. f. mikr. Anat. lix. 3, pp. 315-354,

pis. xviii.-xxi. (1901). II. Op. cit. Ixi. 3, pp. 331-347, pi. xviii. (1902).

62. Billet, A . Sur un Hematozoaire endoglobulaire des Platydactylus (Haemo-

gregarina platydactyli n.sp.). C. R. Soc. Biol. Paris, Iii. 21, pp. 547-
549, 10 figs. (1900).

63. A propos de Haetnamoeba metchnikovi (Simond) des Trionyx. Op.

cit. liii. 10, p. 257 (1901).

64. Sur la presence constante d'un stade gre'gariniforme dans le cycle

evolutif de 1'hematozoaire du paludisme. C. R. Ac. Sci. Paris, cxxxii. 23,
p. 1433 (1902).

65. Borner, C. Untersuchungen liber Haemosporidien, etc. Zeitschr. f. wiss.

Zool. Ixix. 3, pp. 398-416, 1 pi. (1901).

66. Ewing, J. Malarial Parasitology. Journ. Exp. Medicine, v. 5, pp. 429-491,

pis. xxix.-xxxii. (1901).

67. Grassi, B. Die Malaria, etc. 2nd edition, Jena (Gustav Fisher), 4to (1901).

68. Hintze, R. Lebensweise und Entwicklung von Lankesterelta minima

(Chaussat). Zool. Jahrb., Abth. f. Anat. xv. 4, pp. 693-730, pi. xxxvi.
(1902).

69. Hunt, J. S. Progress Report on the Reproductive Forms of the Micro-

organism of Tick-Fever, etc. Queensland Agric. Journ. ii. 3, pp. 211-220,
1 pi. 1 diagram.

70. Koch, R. Reiseberichte liber Rinderpest, etc. Berlin (Julius Springer)

(1898).

71. Labbe, A. Recherches ... sur les parasites endoglobulaires du sang des

Vertebras. Arch. Zool. Exp. et Ge"n. (3), ii. pp. 55-258, 10 pis. (1894).
71a. Lankester, E. R. Note on the Morphological Significance of the various
Phases of the Haemamoebidae. Quart. Journ. Micr. Sci., N.S., xliii. pp.
581-588 (1900).

72. Laveran, A. Traite du Paludisme. Paris (1898).

356 LITERATURE OF THE SPOROZOA

73. Laveran, A. Contribution a 1'^tude de Haemogregarina stepanovi, Danilewsky.

C. R. Soc. Biol. Paris, (10), v. [1.] pp. 885-889, 919-922, 12 figs. (1898).

74. Contribution a 1'^tude de Drepanidium ranarum, Lankester. T.c.

pp. 977-980, 13 figs. (1898).

74a. Contribution a 1'etude de Laverania danilewslcyi, etc. [Halteridium],

Op. tit. (11) i. [li.] pp. 603-606 (1899).

75. Les Hematozoaires endoglobulaires. Op. cit. vol. jubil. pp. 124-133

(1899).

76. Contribution a I'e'tude de Piroplasma equi. Op. cit. liii. p. 385 (1901).

77. Essai de classification des Hematozoaires endoglobulaires, etc. T.c.

p. 798 (1901).

78. Technique pour 1'^tude des " flagelles " de 1'Hematozoaire du paludisme,

etc. Op. cit. liv. pp. 177-180, 6 figs. (1902).

79. Laveran, A., et Mesnil, F. Deux Hemogregarines nouvelles des Poissons.

C. R. Ac. Sci. Paris, cxxxiii. 16, pp. 572-577, 2 figs. (1901).

79a. et Sur les Hematozoaires des Poissons marins. Op. cit. cxxxv.

pp. 567-570 (1902).

80. Laveran, A., et Nicolle, M. Contribution a l'e"tude de Pyrosoma Hgeminum.

C. R. Soc. Biol. Paris, (11), i. [li.] pp. 748-751, 15 figs. (1899).

81. et Hematozoaires endoglobulaires du mouton. T.c. pp. 800-802

(1899).

81a. Ligniires, J. Sur la Tristezza (Piroplasma ligeminum). xiii. Congr. Int.
He'd., Paris, 1900, Sect. Parasitol., pp. 108-116 (1901).

82. Lutz, A. Uber die Drepanidien der Schlangen, etc. C. B. Bakt. Parasiten-

kunde, xxix. pp. 390-397, 1 pi. (1901).

83. MacAllum, W. G. On the Haematozoan Infection of Birds. Journ. Exp.

Medicine, iii. pp. 117-136, pi. xii. (1898).

84. Notes on the Pathological Changes in the Organs of Birds infected

with Haemocytozoa. T.c. pp. 103-116, pis. x., xi. (1898).

85. Marceau, F. Note sur le Karyolysus lacertarum, etc. Arch. Parasitologie,

iv. pp. 135-142, 46 figs. (1901).

86. Marchoux, E. Piroplasma canis (Lav.) chez les chiens du Senegal. C. R.

Soc. Biol. Paris, Iii. pp. 97, 98, 9 figs. (1900).

87. Newu-Lemaire, M. L'Hematozoaire du paludisme, etc. Causeries Sci. Soc.

Zool. France i. 1, pp. 1-24, 2 pis. 11 text-figs. (1900).

88. Les Hematozoaires du paludisme, etc. These, Paris (1901).

89. Nocard et Motas. Contribution a 1'etude de la Piroplasmose canine. Ann.

Inst. Pasteur, xvi. pp. 256-290, pis. v., vi. (1902).

90. Opie, E. L. On the Haemocytozoa of Birds. Journ. Exp. Medicine, iii. pp.

79-101, pi. ix. (1898).

91. Popovici, A. B. Contribution a 1'^tude des parasites endoglobulaires du sang

des Vertebres. Bull. Soc. Sci. Bucarest-Roumanie, x. pp. 329-335, 12
figs. (1901).

92. Sambon, L. W., and Low, G. C. The Mosquito-Malaria Theory. Med.

Chir. Trans. Ixxxiv. 56 pp. pis. xxi.-xxv. 11 figs, [contains description by
R. J. Pocock of the ticks which transmit Texas-fever, with coloured
plate] (1902).

93. Schavdinn, F. Ueber die Generationswechsel bei Coccidien und die neuere

Malariaforschung. S. B. Ges. Nat, Fr. Berlin, pp. 159-178, 1 fig. (1899).

94. Der Generationswechsel der Coccidien und Hamosporidieu. Zool.

Centralbl. vi. pp. 765-783 (1899).

LITERATURE OF THE SPOROZOA 357

94a. Schaudinn, F. Studien iiber Krankheitserregende Protozoen — II. Plas-
modium vivax, etc. Arbeiten a. d. Kaiserl. Gesundheitsamte, Berlin, xix.
2, pp. 169-250, pis. iv.-vi. (1902).

95. Simond, P. L. Sur un Hematozoaire endoglobulaire pigment^ des Tortues.

C. R. Soc. Biol. Paris, liii. p. 150 (1901).

96. Contribution a 1'etude des Hematozoaires endoglobulaires des Reptiles.

Ann. Inst. Pasteur, xv. pp. 319-351, 1 pi. 32 figs. (1901).

97. Smith, T. Die Aetiologie des Texasfieberseuche des Rindes. C. B. Bakt.

Parasitenkunde, xiii. p. 511 (1893).

98. Wright, H. The Malarial Fevers of British. Malaya. Studies from the

Institute for Medical Research, Federated Malay States, i. 1 [Singapore,
Kelly and Walsh] (1901).
See also Laveran et Mesnil [40a].

V. Myxosporidia.

99. Cohn, L. Ueber die Myxosporidien von Esox lucius und Perca fluviatilis.

Zool. Jahrb. Abth. f. Anat. ix. pp. 227-272, 2 pis. (1896).

99a. Zur Kenntniss der Myxosporidien [Sphaerospora masomca], C. B.

Bakt. Parasitenkunde, 1st Abth. xxxii. pp. 628-632, 3 text-figs. (1902).

100. Dqflein, F. Studien zur Naturgeschichte der Protozoen — III. Ueber

Myxosporidien. Op. cit. xi. pp. 281-350, pis. xviii.-xxiv. 20 text-figs. (1898).

101. Fortschritte auf dem Gebiete der Myxosporidienkunde. Zool.

Centralbl. vii. pp. 361-379 (1899).

102. Gurley, H. R. The Myxosporidia or Psorosperms of Fishes, etc. Bull.

U.S. Fish. Comm., Rep. of Comm. 1892, pp. 65-298, 47 pis. (1894).

103. Laveran, A. Sur une Myxosporidie des reins de la tortue [Myxidium

danilewskyi}. C. R. Soc. Biol. Paris, (10), iv. [xlix.] pp. 725, 726 (1897).

104. Sur le Myxidium danilewskyi. Op. cit. (10), v. [L] pp. 27-30 (1898).

105. Laveran, A.,et Mesnil, F. Sur une Myxosporidie des voies biliaires de 1'Hippo-

campe [Sphaeromyxa sabrazesi]. Op. cit. lii. pp. 380-382, 4 figs. (1900).

106. et Sur la multiplication endogene des Myxosporidies. Op.

cit. liv. pp. 469-472, 5 text-figs. (1902).

107. Leger, L. Sur uue nouvelle Myxosporidie de la famille des Glugeide"es.

C. R. Ac. Sci. Paris, cxxv. pp. 260-262 (1897).

108. Liihe, M. Cystodiscus immersus, Lutz. Verb. Deutsch. Zool. Ges. ix.

pp. 291-293, 1 fig. (1899).

109. Lutz. Ueber ein Myxosporidium aus der Gallenblase brasilianischen

Batrachier. C. B. Bakt. Parasitenkunde, v. (1889).

110. Mrazek, A. Ueber eine neue Sporozoenform aus Limnodrilus [Myxocystis

ciliata}. S. B. Bohm. Ges. viii. 5 pp. 9 figs. (1897).

llOa. Sporozoenstudien — II. Ghigea lophii, Doflein. Op. cit. x. 8 pp. 1 pi.

(1899).

111. Stempell, W. Ueber The'lohania mulleri (L. Pfr.). Zool. Jahrb., Abth. f.

Anat. xvi. 2, pp. 235-272, pi. xxv. (1902).

112. Stole, A. Actinomyxidia, nova skupina Mesozou, pribuzna Myxosporidifm.

Rozp. Ceske Ak. Cis. Frant. Jos. II. viii. 22, 12 pp. 3 pis. (1899).

113. TMlohan, P. Recherches sur les Myxosporidies. Bull. Sci. France Belg.

xxvi. pp. 100-394, 3 pis. (1895).

114. Fancy, C., et Conte, A. Sur une nouvelle Microsporidie — Pleistophora

mirandellae, etc. C. R. Ac. Sci. Paris, cxxxiii. pp. 644-646 (1901).

115. et Sur deux nouveaux Sporozoaires endosperms, etc. Ann.

Soc. Linn. Lyon, N.S. xlvii. 1900, pp. 103-106, 4 figs. (1901).

358 LITERATURE OF THE SPOROZOA

VI. Sarcosporidia.

116. Bertram. Beitrage zur Kenntnis der Sarcosporidien, etc. Zool. Jahrb.,

Abth. f. Anat. v.

117. Kasparek, T. Beitrage zu den Infectionsversuchen mit Sarcosporidien.

C. B. Bakt. Parasitenkunde, 1 Abth. xviii. pp. 327-330.

118. Koch, M. Ueber Sarcosporidia. Verh. v. Int. Congr. Zool. Berlin, 1901,

pp. 674-684, 1 fig. (1902).

119. Laveran, A., et Mesnil, F. Sur la Morphologic des Sarcosporidies. C. R.

Soc. Biol. Paris, (11), i. [li.] pp. 245-248 (1899).

120. et De la Sarcocystine, toxine des Sarcosporidies. T. c. pp

311-314 (1899).

121. Smith, T. The Production of Sarcosporidiosis in the Mouse by feeding

Infected Muscular Tissue. Journ. Exp. Medicine, vi. pp. 1-21, pis. i-iv.
(1901).

122. Vuillemin, P. Le Sarcocystis tenella, parasite de 1'homme. C. R. Ac. Sci.

Paris, cxxxiv. pp. 1152-1154 (1902).

VII. Incertae sedis.

123. Brasil, L. Joyeuxella toxoides n.g., n.sp. etc. Arch. Zool. Exp. et Ge"n.,

Notes et Revue, (3), x. pp. v.-vii. 7 figs. (1902).

124. Calkins, G. N. Lymphosporidium truttae nov. gen., nov. sp. etc. Zool.

Anzeiger, xxiii. pp. 513-520, 6 figs. (1900).

125. Caullery, M., et Mesnil, F. Sur un type nouveau (Metchnikovella n.g.),

etc. C. R. Ac. Sci. Paris, cxxv. pp. 787-790, 10 text-figs. (1897).

126. et Sur trois Sporozoaires parasites de la Capitella capitata, 0.

Fabr. C. R. Soc. Biol. Paris, (10), iv. [xlix.] pp. 1005-1008 (1897).

127. et Sur un Sporozoaire aberrant (Siedleckia n. gen.). Op. cit.

(10), v. [1.] pp. 1093-1095, 7 figs. (1898).

128. et Sur le genre Aplosporidium (nov.) et 1'ordre nouveau des

Aplosporidies. Op. cit. (11), i. [li.] pp. 789-791 (1899).

129. et Sur les Aplosporidies, etc. C. R. Ac. Sci. Paris, cxxix. pp.

616-619 (1899).

129a. et Sur les parasites internes des Annelides, etc. [Siedleckia,

Toxosporidium]. C. R. Ass. France Sci. 1899, pp. 491-496 (1900).

129&. Cienkowski, L. Ueber parasitische Schlauche auf Crustaceen, etc.
[Amoebidium parasiticum]. Botan. Zeitung, xix. pp. 169-174, pi. vii.
(1861).

130. Cohn, L. Protozoen als Parasiten in Rotatorien. Zool. Anzeiger, xxv.

pp. 497-502 (1902).
130a. Giglio-Tos, E. Un parassita intranucleare, etc. [Karyamoeba}. Atti.

Ace. Torino, xxxv. pp. 563-569, 1 pi. (1900).
1306. Keppene, N. Hyalosaccus ceratii nov. gen. et sp., etc. Mem. Soc.

Natural. Kiew, xvi. 1, pp. 89-135, pis. vi.-viii. (1899).
130c. Labbe, A. Sur les affinites du genre Siedleckia, etc. Bull. Soc. Zool.

France, xxiv. pp. 178, 179 (1899).

131. Leger, L. Sur un organisme parasite de 1'intestin d'Olocrates gibbus, Fab.

[Raphidospora]. C. R. Soc. Biol. Paris, Hi. pp. 261, 262 (1900).

132. Sur Involution de Raphidospora le Danteci, Leger. T,c. pp. 262,

263 (1900).

LITERATURE OF THE SPOROZOA 359

133. Mesnil, F., and Marchoux, E. Sur un Sporozoaire nouvea.n (Coelosporidium

chydoricola n.g. et n.sp.), etc. C. R. Ac. Sci. Paris, cxxv. pp. 324-326
(1897).

134. Plate, L. tJber einen einzelligen Zellparasiten (Chitonicium simplex), etc.

Fauna chilensis, 2, p. 601 (Suppl. v. to Zool. Jahrb.) (1901).
134a. Przesmycki, A. M. tJber parasitische Protozoen aus dem inneren von

Rotatorien. Bull. Ac. Sci. Cracovie (1901).
134&. Sand, E. Exosporidium marinum (n.g., n.sp. provis.). Bull. Soc. Micr.

Beige, xxiv. pp. 116-119 (1898).

135. Schewiakoff, W. Ueber einige ekto- und entoparasitische Protozoen der

Cyclopiden. Bull. Soc. Imp. Nat. Moscou (N. S.), vii. (1893) pp. 1-29, pi.
i. (1894).

136. Schneider, A. Sur le Developpement du Stylorhynchus longicollis [Chytri-

diopsis socius]. Arch. Zool. Exp. (2) ii. pp. 14, 15, pi. i. figs. 1-4 and 22
(1884).

137. Zacharias, 0. Zum Capitel der " wurstfdrmigen Parasiten" bei Rader-

thieren. Zool. Anzeiger, xxv. pp. 647-649 (1902).

See also Bertram, No. 116 [Description of Bertramia] and Caullery and
Mesnil, No. 86 [Siedleckia],

ADDENDUM TO BIBLIOGRAPHY.

The following memoirs have appeared too late to be noticed in the above
eview of the Sporozoan orders.

Berndt, A. Beitrage z. Kenntniss der im Darme der Larve von Tenebrio molitor
lebenden Gregarinen. Arch. f. Protistenkunde, I. 3, pp. 375-420, pis.
xi.-xiii. (1902).

[Three species are distinguished, and studied in detail : Cfregarina poly-
morpha (Ham.) ; G. cuneata, Stein ; and Gf. steini n.sp.]

Blanchard, L. F. Gregarine coelomique chez un Cole"optere. C. R. Ac. Sci.
Paris, cxxxv. pp. 1123, 1124 (1902).

[Monocystis Ugeri n.sp. in Carabus auratus.}

Jacquemet, M. Sur la Systematique des Coccidies des Cephalopodes. Arch. f.
Protistenkunde, II. i. pp. 190-194 (1903).

[The name Lfyeriiia is proposed for Benedenia ; the genus is characterised
by polysporous oocysts and by lacking schizogony ; it includes two species :
(1) L. octopiana (Schn.), with from 6-12 sporozoites in the spore, occurring
in Octopus vulgaris and Eledone moschata ; (2) L. eberthi (Labbe), with 3 or
4 sporozoites, from Sepia officinalis. In both forms cysts are found con-
taining macrospores with macrosporozoites and other cysts containing micro-
spores with microsporozoites, perhaps representing a sexual differentiation
thrown back to the earliest stages of the life-history.]

Labb4, A. Article Sporozoa, in Encyclop. Brit., 10th ed., vol. xxxii. pp.
814-818, 5 text-figs. (1902).

[Gives a brief general account of the Sporozoa. The author appears to
use the word " macrogamete " in the sense of a female merozoite ; see above,
p. 210, footnote.]

Laveran, A, Sur quelques Hemogregarines des Ophidiens. C. R. Ac. Sci. Paris,
cxxxv. pp. 1036-1040, 13 text-figs. (1902).

[The snakes in question are Ancistrodon piscivorus, Crotalus confluentus,
Naja tripudians, and Zamenis hippocrepis ; see List of Hosts, pp. 345-347.]

360 LITERATURE OF THE SPOROZOA

Laveran, A. Au sujet du role des Tiques dans la propagation des Piroplasmoses.
0. R. Soc. Biol. Paris, Iv. 2, p. 61 (1903).

[Controverts the statements and conclusions of Me"gnin (infra).]
Lutz, A., and Splendore, A. Ueber P6brine und verwandte Mikrosporidien,
etc. 0. B. Bakt. Pk. (1) xxxiii. pp. 150-157, 12 text-figs. (1903).

[See List of Hosts.]

Mtgnin, P. Du role des Tiques . . . dans la propagation des Piroplasmoses.
C. R. Soc. Biol. Paris, Iv. No. 1, and further notes in following numbers
(1903).

[Contests the role alleged to be played by ticks in transmitting the
infection of the Piroplasma (p. 262).]

Metzner, E. Untersuchungen an Coccidium cuniculi, I. Arch. f. Protistenkunde,
II. 1, pp. 13-72, pi. ii. (1903).

[Each of the four sporoblasts gives off a " Schneiderian body" before
becoming a spore. Each sporocyst has a tiny micropyle. The spores
liberate their sporozoites under the action of the pancreatic fluid, not under
that of the gastric juice.]

Perez, C. Le Cycle evolutif de I'Adelea mesnili, etc. T.c. pp. 1-12, pi. i. 4
text-figs.

[The merozoites destined to form ? gametocytes are distinguishable
from those destined to form <J cells. The gametocytes are sharply distinct,
and form precocious associations, but the $ gametocytes may form <J
gametes apart from the ? cell, in which case, however, the <J gametes
come to nothing.]

THE PEOTOZOA (continued)

SECTION L. — THE INFUSORIA OR CORTICATA HETEROKARYOTA *

THIS group is clearly marked off from other Corticata by the
occurrence of cilia, suckers, or tentacles in the active phase of life
of all species. A character which is of far greater morphological
importance, however, is the presence in each individual of two
distinct nuclear elements called the meganucleus and micronucleus
respectively.

The group is divided into two classes : —

THE CILIATA (Ehrenberg).
THE ACINETARIA (Lankester).

The Ciliata are either free or fixed forms with cilia disposed in
tracts or bands on the cortex.

The Acinetaria are fixed or sedentary forms provided with
suckers or tentacles. They give rise to free-swimming individuals
which are ciliated.

HABITS. — The habits of the animals included in this group are
very variable, and may be conveniently studied as arranged in
five categories, — the free-swimming habit, the creeping or crawling
habit, the stalked fixed habit, the epizoic habit, the endozoic habit.

The Heterokaryota with free -swimming habits principally
belong to the group of the Ciliata. They may be found in pure
pond water (Spirostomum, Paramoecium sp., etc.), swimming freely
near the surface or hovering about the mud at the bottom, or even
coursing about the water in the intermediate depths. A consider-
able number of genera are marine.

Their food consists principally of minute animal and vegetable
organisms that they find floating in the water, but they will also
seize and devour particles of organic matter set free by the
dissolution of animal or vegetable bodies after death. Some
species appear to find their maximum vitality in water containing
putrefying matter, in which case their food consists chiefly of

1 By S. J. Hickson, F.R.S.

362

THE INFUSORIA

Q

Bacteria. In all cases they move with a good deal of activity,
sometimes with a uniform speed and sometimes with short starts
and stops alternating with considerable regularity. It may be
noticed that in any case one end of the animal's body is habitually
in front, and that when it wants to change the direction of its
progress it turns round. This enables us to speak definitely of an
anterior and a posterior end as in the bilaterally symmetrical metazoa.
The two ends of the body are frequently so much alike in form
and as regards the disposition of the cilia (many species of
Paramoecium) that in killed and preserved specimens they are
almost indistinguishable. In many cases, however, the anterior
end may be distinguished by being more pointed (Spirostomum), by
the conspicuous mouth (Prorodori), by the presence of peculiar
sensory cilia (HYPOTRICHA), or by a special
collar (peristome) of long cilia on the margin
of a spiral ridge (HETEROTRICHA) round the
mouth. It is not always possible to define
the limits of the dorsal and ventral surfaces,
as the body may be almost spherical in shape,
and the cilia may be of approximately
equal length and evenly distributed on the
surface. In such forms, the progression of
the animal is accompanied by a more or less
rapid rotatory movement round the long axis
of the body. In other cases, however, the
body is flattened (Paramoecium) and the
dorsal and ventral surfaces fairly well de-
nned.

Among those forms that habitually crawl
or creep over surfaces, the body is generally
oval in outline and considerably flattened
dorso-ventrally. A further peculiarity is
frequently found in the specialisation of
some of the cilia to serve the purpose of
locomotion, and perhaps also the functions
of touch and taste (Fig. 1, a and b). These
cilia are usually called cirri, and are dis-
tinguished by their thickened bases and con-
siderable length.

Among the sedentary forms there is a

-,.•,-, P T n

decided prevalence of more radially sym-
metrical shapes, with a restriction of the
cilia to a definite ring or series of rings
round the mouth. It is in the sedentary
forms, too, that we often find incomplete fission, leading to the
formation of colonies of several individuals organically connected

FIG. 1.

Ventral view of Oxytricha,
a creeping Hypotrichan. o,
frontal cirri, probably sensory
in function ; b, caudal cirri ;

vacu°le'

THE INFUSORIA

363

together. In some sedentary species, too, there is a secretion of a
mucous substance, frequently strengthened by foreign particles,
which serves as a protective tube or case. This may be auto-
thecalous (Fig. 83), when the tube of each individual is distinct,

FIG. 2.

Ophi-ydium eichornii, Ehrb., a colonial Peritrichan with a coenothecalous mucilaginous
test. British. Freshwater. Size of colonies about 4 mm. in length.

or coenothecalous (Ophrydium, Fig. 2), when the secretions of the
individuals composing a colony form a common test perforated by
a series of tubes.

A large number of the sedentary forms are epizoic. Some
species of Epistylis are found on the appendages or body wall of
Cyclops and other small Crustacea,
but in this instance the epizoic
habit does not appear to be neces-
sary, as the same forms may also
be attached to water weeds or other
objects. There are other genera,
however, which are only found
upon the bodies of living animals,
and seem to be dependent on their
host for suitable conditions of exist-
ence,— such are Dendrocometes and
Spirochona on the gills of Gammarus,
Kentrochana on the gills of Nebalia
(Fig. 3), and Cothurniopsis on the
gills of Astacus. In these cases no
special modification of structure can
be attributed to the epizoic habit.

A great many genera are ento

ZOic in habit, being found Only in

the intestines, bladder, or blood of

other animals. The remarkable

consistency with which some of these forms occur in a particular

situation in only one species of host, is similar to the partiality

FIG. 3.

Kentrochona nebaliae, from the maxilli-
ides of Nebalia. Size about '04 mm.

364

THE INFUSORIA

exhibited in this respect by many parasites belonging to other
classes of the animal kingdom ; but although the entozoic Infusoria
are frequently called parasites, it is doubtful whether this term is
correctly applied to them. The general conception of a parasite
is an organism that gets its food and protection at the expense of
its host, and that when present in considerable numbers causes
injury or weakness.

There is no evidence at present that the Infusoria feed upon
anything except substances that would, without their presence, be
ejected from the body of the host ; and it is quite possible that by
disintegrating certain substances in the alimentary canal, they may
be advantageous rather than deleterious to their hosts. The structure
of the entozoic Infusoria is so varied that it is usually impossible to
recognise in them any special adaptation to their environment.
The mouthless Opalina found in the bladder of frogs may owe its
many peculiarities of form to entozoic habits, but there is nothing
of importance in the structure of Nyctotherus, occurring in the
rectum of the same animal, that can be regarded as associated with
its peculiar habitat.

Some groups of animals appear to afford much more favourable
conditions for the entozoic Infusoria than others. They are rarely
absent from the rectum and bladder of adult
Amphibia, the intestines of white ants and
other Orthoptera are frequently crowded
with Trichonymphidae, and the alimentary
canal of cows, horses, and other herbivorous
mammalia support a large number of remark-
able genera. In the coecum of the horse,
Bundle has found no less than thirteen dis-
tinct species. (Cycloposthium,, Blepharocorys
(3 species), Fig. 4, Paraisotricha (3 species),
Didesmis (2 species), Biitschlia, Blepharopros-
thium, Blepharosphaem, and Blepharocodon.}
They have not been found in the Carni-
vora. In the intestines of man, Balantidium
minutum and Nyctotherus faba occasionally
occur.

SIZE. — The size varies considerably.
Some of the elongated forms, such as Spiro-

~ mm-

appendage. wnen fu\\y expanded, but the more compact

oval or rounded forms rarely reach a greater
size than I'o mm. in their longest axis (e.g. Bursaria). The usual
size is between this and 0'04 mm. in length (e.g. Cinotochilum).

The substance of the body is clearly differentiated into an
outer, more solid cortical sheath and an inner, semifluid

4-M

FIG. 4.

Blepharocorys uncinata, Fior.,
from the coecum of the horse.
M, meganucleus ; m, micronu-
clei ; C.V., contractile vacuole ;
A, anus surrounded by cilia ;
C, mouth ; h, hood overhanging , . f n

the mouth, bearing many long stomum, may attain to a length of 3

THE INFUSORIA

365

medullary substance. To these the terms exoplasm and endoplasm
respectively are usually applied by authors, but, as pointed out
by Lankester, it is important that the permanent arrangement of
the living substance in the INFUSORIA should not be confounded
with the transitory arrangement of the particles forming the
exoplasm and endoplasm of the GYMNOMYXA, and it is therefore
advisable to retain in this connection the terms "cortex" and
" medulla."

CORTEX (Ectosarc, Ectoplasm). — The cortex is, in its simplest
form, a clear, firm outer layer of protoplasm, bearing the cilia or
suckers, and showing no evidence of further differentiation even
with the highest powers of the microscope. In some of the larger
Heterokaryota, however, three distinct layers may be recognised —
an outer very thin skin, called the pellicle ; a lower layer, usually
characterised by a series of vertical and parallel lines, called the
alveolar layer ; and an inner layer of clear transparent protoplasm
continuous with the medulla, and distinguished from it only by
the scarcity of granules and the absence of food vacuoles.

These three layers are in all cases organically continuous, and
are rightly regarded as being built up of living substance.

The pellicle is rarely more than 1 //, in thickness, but most
frequently it is so extremely thin as
to be only just distinguishable in
section. It is apparently very tough,
and where it is grooved or ringed
it determines the outline of the
body. In some forms it gives rise
to hard hook-like processes, as in the
parasite Trichodina, or to a mailed
armature, as in Coleps (Fig. 5).

The alveolar sheath is usually
much more apparent than the pell-
icle, and is very frequently marked
by longitudinal lines which are
regarded as indications of specialised
strips of contractile protoplasm. It
is only in a few forms that these
strips are sufficiently differentiated
to be distinguished as specialised
muscular fibrils. In such cases, how-

Fia. 5.

cdeps

Bhr> one of the mailed
A, one of the 15 rows of

ever, they are enclosed in a canal Hoiotricha.

•i •• ,i ,i -i F plates. (From Butschli, after Maupas.)

sunk beneath the general surface x 900. Freshwater.

of the alveolar layer, and are called

myoneme threads (Fig. 6). Of great interest are the myoneme threads

occurring in particular parts of the body of some genera such as

the sphincter of the peristome in Epistylis, the " myophan " thread

366

THE INFUSORIA

in the stalk of Vorticella, and the remarkable myoneme bands for
the retraction of the peristome in Cycloposthium.

It is usually the alveolar sheath which bears the pigment of
those forms that are specially coloured, such as the blue Stentorin
of Stentor coeruleus, but the colour may also be due to pigments in

Fio. 6.

Section through the outer layers of
Holophrya discolor, a, the alveolar
sheath covered by a very thin pellicle ;
R, the surface ridges, between which
are the rows of cilia ; M, the vertical
canals bearing the myoneme fibres; E,
the medulla. (After Btitschli.)

the pellicle or in the medulla. It is in the same layer that the
trichocysts occur. These are described more fully below.

The inner layer of the cortex does not present any features of
very special interest. It is frequently quite inconspicuous.

The MEDULLA. — This part of the body is, in almost all cases,
the larger in bulk. It is usually semifluid in consistency, and
exhibits a constant rotatory movement. In Trachelius (Fig. 7)
and some others it exhibits a reticulate char-
acter, with irregular branching pillars stretching
from the centre to the cortex. In Dendro-
cometes among the Acinetaria very fine lines may
sometimes be seen stretching from the arms to
the region of the meganucleus, but in most
cases the particles composing the medulla seem
to be freely interchangeable in position.

The bodies held in suspension by the
medulla are very diverse and variable. Apart
from the food vacuoles, contractile vacuoles,
and nuclei, which are described in some detail
a frlSTr HoZtric^an,' in an<>ther place, there are often to be found
showing the reticulate ar- pigmented granules, colourless spherules, crystal-

rangement of the medul- ?• v j- j -M _,• i i • -i

lary protoplasm. 6, 6 the line bodies, and smaller particles, which vary
the SSStCdSW in size and number according to the state of
x so. nourishment and sexual condition of the in-

dividual.

The Mouth (Cytostom) is present in nearly all the Ciliata, the
parasitic Opalina, TrichonympJut, and one or two other genera forming
interesting exceptions to the general rule. In the Acinetaria there
is usually no mouth.

In its simplest form the mouth is represented by a small slit-
shaped break in the continuity of the cortex at the anterior end of
the body. This can be opened for the reception of food, but in
the intervals of ingestion is kept closed (Enchelina, etc.). In other

Fio. 7.

THE INFUSORIA

367

forms the mouth, though still in its primitive position at the anterior
end, is always open, and presents a clear passage from the exterior
to the medulla (Prorodori) (Figs. 8 and 9). In Torquatella (Figs. 12
and 66) there is a lip-like, supra-oral lobe projecting above the
mouth, and in Trachelius (Fig. 7), Spirostomum, and other genera,
there is a long, pointed prostomial process. It is impossible to
determine whether this prostomial process is rightly regarded as
an outgrowth in front of the mouth, or whether it is due to a shifting
backwards in the position of the mouth, but in such forms as
Paramoecium, and in the Hypotricha generally, the ventral position
of the mouth can only be explained on the supposition that, in
accordance with the method of feeding, it has shifted its position
from the primitive one at the anterior end of the body.

In most of the Ciliata very little differentiation can be observed
in the protoplasm surrounding the oral aperture, but in a few cases

FlO. 9.

The horny fascicu-
late lining of the
mouth of Prorodon
isolated.

Fio. 8.

Prorodon nivens,
Ehr., one of the Holo-
tricha. a, nucleus ; 6,
contractile vacuole ;
c, mouth with horny
fasciculate lining.
X 75.

Fio. 10.

Section through the mouth and
pharynx of Urotricha lagenula, Kent.
m, mouth ; Ph, pharynx ; c, cortex ; M,
medulla. (After Schswiakoff.)

a series of rod-like thickenings of the cortical pro-
toplasm guard the mouth. In Prorodon (Fig. 8),
for example, there is a paling arrangement of such
rods which appears to serve the purpose of keeping the aperture
distended. In Urotricha these rods make an apparatus of a more
complicated type sunk below the plane of the mouth, forming
what might be called a pharynx (Fig. 10). The mouth of the
Infusoria may be situated either at the surface of the cortex or
sunk to the bottom of a funnel-shaped depression usually called
the vestibule, and on the slopes of this or in the neighbourhood of
its margin many specialised differentiations of cilia or groups of
cilia may be found (the paroral cilia) adapted to the function of
driving the food into the mouth (Blepharocorys, Fig. 4).

The mouth or the vestibule is sometimes overhung by one or
two membranous expansions of the cortex, the free edges of which
are provided with a special row of cilia. In Opercularia this
membrane is like a lid or operculum which closes the aperture of
the vestibule before the peristome is contracted.

368 THE INFUSORIA

Another noteworthy feature of the mouth region are the tracts
of trichocysts which are occasionally seen (Dikptus, Amphileptus}
leading from the anterior part of the prostomial lobe to the mouth.
The specialisations of cilia and other structures in the region of
the mouth of these animals are so numerous, however, that a
description of the conditions met with in each genus would be
necessary to do justice to the subject.

There can be no doubt that in some forms, such as Blepharocorys
(Fig. 4), Nydotherus (Fig. 56), etc., a definite cytopyge or cell-anus
does occur, and in others (certain species of Entodinium) the anus
opens into a groove-like depression of the surface. As a general
rule, however, there is no definite opening of this character, and
the undigested parts of the food are simply pushed through the
cortex at some particular region of the body.

CILIA, CIRRI, MEMBRANES, AND TENTACLES.

In all the Heterokaryota there are to be found delicate proto-
plasmic processes from the general surface of the body, which
perform the function of locomotion and ingestion of food or of
sensation. These may have the form of very delicate and short
whip-like threads, which are called cilia ; coarse, blunt, or pointed
processes, which are called cirri ; expanded, flattened membranes ; or
the remarkable suckers and tentacles of the Acinetaria.

It is not an unreasonable hypothesis that in the ancestral forms
the processes had the form of cilia, and that in the process of differentia-
tion of the Heterokaryote body, the cilia in certain regions became
fused together to form cirri and membranes, or differentiated to
form suckers and tentacles. The view that the ciliated body was
the most primitive is supported by the facts that the genera of the
class Ciliata, which are apparently the simplest in general structure,
exhibit no modification of their ciliary apparatus, and that in the
highly differentiated Acinetaria the free-swimming buds are always
provided with bands or tracts of unmodified cilia until they assume
the sedentary habit.

The cilia in their simplest form are composed of the clearest
and most homogeneous kind of protoplasm, in which no granules
nor fibrils of any kind can be discovered. They spring from the
pellicle, and, as Biitschli has clearly shown, are continuous with it.
In many forms they undoubtedly appear to penetrate through the
alveolar layer into the subjacent medulla, but this appearance can
be best accounted for by the view that they are usually supported
and influenced by a specialised thread of the cortical protoplasm
attached to their seat of origin. They rarely exceed the extreme
length of 16 /z, and they vary from O'l p. to 0'3 /z, in diameter.

THE INFUSORIA

369

Their particular arrangement on the surface of the body is one
of the chief characters used in classification, and will be described
under the several orders and sub-orders, but it may be mentioned
here that when the cilia are arranged in definite rows or circles
they are not infrequently united at their bases by a very delicate
membrane or webbing which may be called a membranella.

In the remarkable parasites allied to TrichonympJia (Fig. 11),
some of the cilia appear to be of re-
markable length, and unlike ordinary
cilia in other respects. According to
Porter, the shorter cilia of the middle
region of the body are mainly re-
sponsible for the active movements so
characteristic of the parasite ; the
longer cilia, which cover the greater
part of the posterior region of the
body, vibrate but little, while the cilia
at the posterior extremity are abso-
lutely motionless. The function of
the motionless cilia appears to be to
entangle and hold particles of food
which are subsequently ingested by
the cortex of the body in this region.

In another parasite, Pyrsonympha
vertens (Fig. 84), the body is covered
with a few short cilia, but an enor-
mously elongated and very delicate a, the nucleus ; b, granules of food.

H j ,1 j ,v Parasitic in the intestine of white ants.

process, called the peduncle, at the x eoo.
anterior end, penetrates deeply into

the epithelium of the host's intestine and fixes the parasite
in its position. The nature of this peduncle is difficult to deter-
mine, but it is probable that it represents an extremely specialised
form of cilium adapted to the function it performs. This peduncle
may be as much as 75 p. in length and 1'5 //, in diameter. A
similar peduncle occurs in the Holotrichous parasite Blepharocorys
(Fig. 4).

The cirri are very characteristic of the group Hypotricha,
although occasionally found elsewhere. They usually arise from a
broad base and rapidly narrow distally to an extremely fine point.
In section they may be round, oval, semicircular, or even polygonal.
The cirri found on the margin of Euplotes are regularly frayed out
at the ends, and the posterior cirri of the Oxytrichinae are very
much flattened (Fig. 1). In many of the larger forms of cirri it
can be shown that a bundle of very delicate lines or fibrils runs
from the base to the apex. The nature of these cirri has been
a subject of some discussion among microscopists, but the view

24

Fio. 11.

TrichonympJia agilis, Leidy. The

370

THE INFUSORIA

Fio. 12.

advocated by Maupas that they represent a bundle of fused cilia
appears to be the most reasonable one to adopt.

The membranes which occur in some of the Ciliata in place of
cilia may be regarded as due to an increase in the membranellae or
webbings which are not infrequently found at the base of the rows
of cilia previously mentioned (Fig. 70).

These membranes, however, are so delicate that it is difficult to
find any trace of the individual cilia of which it is supposed they
are mainly composed. The spiral membrane of Spirochona (Fig. 22)
is, in form, so similar to the spirally arranged rows of cilia round
the vestibule in other CILIATA, and the collar-
like membrane of Torquatella (Fig. 12) is so like
the crown of cilia in the allied genus Strombidium
(Fig. 65), that the burden of proof that they
are not formed by the fusion or amalgamation
of rows of cilia falls upon those who maintain
their independent origin.

In the ACINETARIA it appears that two
Torquatella typica, phases of life regularly occur — a free-swimming

Lank ester, found asso- r ° J

ciated with the eggs of phase and a fixed or sedentary phase. In the
Thefmouth ts orerhuifg former, cilia occur arranged in bands or patches
by a crescent -shaped wnich do not differ in any essential respect from

epistomial lobe, and » *

there is a membranous those found in ClLiATA. In the latter phase,

fringe on the circumoral •, .•• .,. ••. •• -i r

disc. however, the cilia disappear, and a number ot

processes are formed which are
called tentacles, suckers, or arms according to their
shape, size, and general features. The morphology
of these processes is not clearly understood.

In Rhynceta cyclopum (Fig. 13) there is only one
elongated process, ending in a suctorial extremity.
This process is on the one hand similar to the
suckers of other Acinetaria, and on the other hand
might be regarded as the attenuated hypostome
bearing the mouth of this remarkable form. If we
regard Rhynceta as a primitive form, the suckers of
the Acinetaria might be regarded as formed by a
multiplication of the mouths and hypostomes of a
remote ancestor similar to Rhynceta, and the tentacles
and arms as modifications of these primitive
hypostomes. Such an elaborate hypothesis is not
necessary, and there is no reason why all these
processes of the Acinetaria should not be regarded
as highly specialised cilia or cirri.

The simplest forms of tentacles are delicate
pointed processes which in their fully extended condition have
the same appearance as large cilia or small cirri. They differ

FIG. 13.

Rhynceta cyclo-
pum, Zenker, an
Acinetarian with a

tractile
X 150.

vacuole.

THE INFUSORIA

37i

Fio. 14.

Ephelota gemmipara, Hertwig, a stalked
Acinetarian, showing both tentacles and
suckers on the disc, b, b, contractile
vacuoles. (After R. Hertwig.) x 100.

from cilia, however, in their movements, which are intermittent
and relatively slow, and also in their considerable powers of re-
traction, which is accompanied by the
appearance of a spiral ridge (Fig. 14).
According to some authors there
is a further difference from cilia in
the presence in the suckers of a cen-
tral lumen or canal. It is quite
probable that the protoplasm in the
axis of the tentacles is more fluid
than at the periphery, and therefore
gives the appearance of a canal ; but
it is very improbable that in any

forms a true Open lumen OCCUrS.
rn, , T/V. r i

ihe SUCkerS diner from the ten-

tacles in being usually uniformly

cylindrical in shape, and by ending

in blunt, swollen, or cup-shaped extremities. They are frequently

extremely extensible (Fig. 15), and exhibit during retraction a

spiral thickening similar to that of the tentacles.

The arms of Dendrocometes (Fig. 85) and Stylocometes
have probably arisen by the fusion of bundles of
tentacles or suckers. They bear at their extremities
short papilliform or filiform processes which perhaps
represent the free ends of the individual tentacles of
which they are composed.

The retraction of the tentacles or suckers may be
rapid or slow, and very frequently during the retraction
a spirally arranged ridge appears on the surface, which
may be regarded as the specially contractile filament
of protoplasm which is concerned in the retraction.
The arms of Dendrocometes and Stylocometes are also
occasionally withdrawn to the level of the general sur-
face of the body, but this process takes from two to
three hours to accomplish, and is not accompanied by
any spiral thread appearance.

TRICHOCYSTS occur almost exclusively in the Holo-
tricha. They are spindle-shaped rodlets situated in the
cortex close to the pellicle, having the power of suddenly
shooting out a thin thread-like process when influenced
by certain stimuli. In Paramoecium (Fig. 46) they are
4 /x in length and in Dileptus 12 ^ but no further
(After details of their structure have been satisfactorily de-
Kent-) scribed. In a few instances it has been observed that
the exploded trichocysts have had a paralysing effect

upon minute organisms, and by analogy it may be assumed that

Fio. 15.

A single sucker
of an Acine-
tarian.
Saville
X 800.

372 THE INFUSORIA

this is usually their function in the Holotricha ; but it is quite
possible that in some cases they may be used primarily or entirely
as organs of defence. In Paramoecium (Fig. 46) they are evenly dis-
tributed in the cortex. In Prorodon they are confined to the anterior
end, and in the Amphileptina to the ventral side of the body.

In Epistylis umbellaria among the PERITRICHA large oval nemato-
cysts 85 fj. in length have been described (Fig. 75). They bear a
thread which before the discharge is coiled up in a capsule in the
manner of the thread in the Coelenterate nematocyst. When the
nematocyst has exploded, the thread is eight to ten times the length
of the capsule. It is a remarkable fact that neither nematocysts
nor trichocysts have been hitherto found in any other genus of the
Peritricha.

NUCLEI. — In a large number of the genera included in the
Heterokaryota two distinct kinds of nuclei have been observed,
which differ from one another not only in size, but in form, structure,
and mode of division. They are called Mega-nuclei and Micro-nuclei
respectively. The micro-nuclei are frequently so small and so
difficult to distinguish from other particles in the protoplasm which
are stained by nuclear dyes, that their existence has been repeatedly
denied in species (Dendrocometes paradoxa, etc.) in which they are
undoubtedly present. The research of the last few years points to
the conclusion that all the Ciliata and Acinetaria are Heterokaryote.

THE MEGANUCLEUS ( = MACRONUCLEUS).

The shape of the meganucleus 1 varies greatly in the order. In
some genera, such as Paramoecium (Fig. 46), Trichonymplut, and others,
it is either oval or spherical in shape during the whole of the
resting-stage. In Carchesium, IForticella, and others it is much more
elongated, and assumes the form of a curved or bent sausage. In
Stentor (Fig. 44), Spirostomum, and others, it is moniliform during the
resting-stage, but contracts into an oval shape before normal fission
occurs. In several genera of Hypotricha and Holotricha the mega-
nucleus divides repeatedly after, or in some cases just before, fission,
and ultimately breaks up into numerous minute fragments scattered
through the medulla. This condition of fragmentation persists until
the animal is ready for another act of fission, when the fragments of
the meganucleus fuse together again into a single spherical or
oval body (Figs. 16, 17, and 18).

A similar phenomenon of fragmentation of the nucleus has been
observed in the genus Opalinopsis (Fig. 19), but in this case unequal
fission may occur without the return of the nuclear fragments to
form a single compact mass.

1 The prefix mega- (Greek (neyas = big) is preferable to macro- ( Greek ftaicpos =
long), and is less readily mistaken for micro-.

THE INFUSORIA

373

Fio. 16.

Oxytricha scutellum,
Cohn. Prepared speci-
men, showing numer-
ous fragments of the
meganucleus scattered
in the medulla. (After
Gruber.)

Fio. 17.

Oxytricha sciUellum,
Cohu. The fragments
having fused into a
single meganucleus,
this has again divided
into two nuclei antece-
dent to fission. (After
Gruber.)

-M
M

Fio. 19.

Opalinopsis sepiolae,
Foett. x about 200,
to show the remark-
ably branched and
twisted meganucleus
(a, a).

Fio. 18.

Lacrymaria (Trachflocerca) phoenicop-
terus, Cohn, from a prepared specimen,
showing the meganucleus. M, M, frag-
mented into a large number of small
granules scattered through the proto-
plasm. (After Gruber.)

Fio. 20.

A preparation of an
undescribed species of
the Acinetarian genus
Ephelota, from the
Cape of Good Hope, to
show the ring-shaped
meganucleus, with
knob - like processes,
and the three minute
micronuclei. (Ori-
ginal.) Marine. '05
mm. across disc.

Fio. 21.

Ephelota (sp. ?), from a stained prepara-
tion of an individual with 16 buds, to show
the branching and anastomosing mega-
nucleus. Size about "5 mm. in length and
•16 mm. across the disc. (From Ishi-
kawa.)

374 THE INFUSORIA

Among the Acinetaria many curious forms of meganucleus have
been described. In full-sized specimens of a species of Ephelota
(Fig. 20) the meganucleus has the form of a ring situated in a plane
parallel with the crown of tentacles. From this ring several knob-
like processes project, some turned towards the crown and others
towards the stalk.

In another species described by Ishikawa the meganucleus of
the adult is in the form of a coarse-beaded network (Fig. 21). In
Dendrosoma it is a thick smooth band occupying the axis of the
branches.

In some cases remarkable changes in the shape of the mega-
nucleus occur which seem to have no connection with the repro-
ductive processes. In Dendrocometes, for example, it may take the
shape of an elongated spindle and move to almost any position in
the cytoplasm. It has even been seen to retreat entirely into one
of the arms. It may also be assumed, from its very irregular form
in many species of Acineta, Eplielota, and other genera, that the
meganucleus normally undergoes amoeboid contortions during the
whole period which elapses between successive acts of reproduction.

Very different accounts have been given of the minute structure
of the meganucleus in the group. It is clear, however, that at least
two elements enter into its composition — a substance that may be
called the Chromatin, having a great affinity for ordinary nuclear
stains ; and a substance which resists nuclear stains, and may be
called the Achromatin. The chromatin is usually in the form of a
close-meshed network of fibrils extending through the whole space
occupied by the meganucleus, and it gives with low powers of the
microscope the appearance of a crowd of granules. Under unfavour-
able circumstances this network may be gathered up into a series
of bunches, and each bunch may be ultimately torn away from its
neighbours, giving the chromatin the appearance of being arranged
in a series of irregular and frequently vacuolated granules. If the
unfavourable circumstances continue, disintegration of the mega-
nucleus may follow, but recovery from the granular condition is
quite possible, and the chromatin may again resume the form of
an evenly distributed network. Changes in the shape of the mega-
nucleus may lead to the deceptive appearance of change in structure.
Thus the meganucleus of Dendrocometes when it assumes the spindle
form appears longitudinally striated, and in its constriction during
bud-formation there is an appearance that might be mistaken for a
row of -independent fibres in the narrowest part of the neck (Fig. 31).
Careful analysis of these striae and rod appearances proves, however,
that in all cases they are due to a rearrangement of the meshes
of the primary network. Local thickenings of the fibrils of the
chromatin network frequently occur, and in some forms acquire
considerable size, but it seems probable that chromatin granules

THE INFUSORIA

375

entirely disconnected from the network only occur in a few
forms.

In Spirocliona there is a remarkable arrangement of the elements
of the meganucleus, the chromatin being collected into a thin, saucer-
shaped mass, leaving a spherical space of clear achromatin in which
during the resting-stage a large deeply-staining spherule occurs (Fig.
22). The nature of this granule is very uncertain. By Balbiani
it was regarded as combining the characters of the centrosome and
nucleolus of the Metazoan cell. Before the division of the mega-
nucleus (Fig. 23) it disappears, and cannot be traced again until
after the separation of the daughter meganuclei. In this respect

FIG. 22.

Spirochonageinmipara, Stein, from
a stained preparation, to show the
meganucleus (M) in a state of rest
and one micronucleus (m). Size
about O'Oo mm. in length. (Original.)

FIG. 23.

Spirockona gemmipara during the
formation of a gemmula, showing
that, during the division of the
meganucleus, the nucleolar body is
absent. (From an original prepara-
tion.)

it undoubtedly claims to be ranked in the category of nucleolar
structures ; but its claim to rank as a centrosome as well is, for
many reasons, unsatisfactory.

It is still an open question whether any of the meganuclei are
surrounded by a definite membrane of a distinct texture. The
appearance of a membrana limitans, which may be seen in all
stained specimens mounted whole, is not always seen when the
meganuclei are cut into thin sections, and it may therefore be
accounted for as an optical effect due to the difference in density
between the nucleoplasm and the surrounding cytoplasm. This
explanation, however, will not account for the facts observed in
all cases, and it seems to be certain that a membrane of a distinct
chemical character is formed between the nucleoplasm and cyto-

376 THE INFUSORIA

plasm in some species. It is, however, always extremely thin and
flexible.

THE MICRONUCLEUS. — Whilst it cannot yet be said that a
micronucleus has been proved to exist in all Ciliata and Acinetaria,
the careful researches of recent years renders it extremely probable
that one or more micronuclei form an essential feature of their
organisation. The difficulty of determining this important fact
with certainty is that, during the long period of rest which the
micronuclei pass through between the acts of fission, gemmation, or
conjugation, the chromatin, as well as the achromatin, elements
shrink into such a small compass that they are not easily seen.
The usual appearance of a micronucleus in the resting-stage is that
of a minute irregular granule lying in the centre of a perfectly clear
vacuole. No lines nor dots can be seen in the vacuole, but it seems
probable from events which occur during division that the clear
substance contained in the vacuole is the same as the achromatin
of the karyokinetic figure.

The size of the micronucleus in the resting-stage is rarely more
than 1 0 p,, but more frequently it is 1 /x, or even less in diameter. It
is 2 p. in Dendrocometes, 4-5 p in Prorodon, and 12-14 //, in Para-
moecium bursaria, in which species it seems to reach its maximum
size.

The staining reactions of the micronucleus in rest are the same
as those of the chromatin of the meganucleus.

The number of micronuclei in the individual varies considerably.
In most species there is only one (Paramoecium caudatum, Colpidium
colpoda, Vorticella monilata, etc.) ; in others there are normally two
(Paramoecium aurelia), or three (Spirochona), or any number up to as
many as twenty-eight (Stentor roeselii). The number is not always
constant in the same species. Maupas, for example, found three
micronuclei in some individuals of Paramoecium aurelia. In Den-
drocometes the number varies from two to five ; Spirochona gemmipara
has, according to Hertwig, normally three micronuclei; but in several
specimens examined in Manchester, Hickson could only find one.

DIVISION OF THE NUCLEI. — There is a very important difference
to be observed in the division of the meganuclei and micronuclei.
The meganuclei divide only during fission or gemmation, except in
those cases mentioned above in which the meganucleus breaks up
into a few or many pieces, after fission of the individuals. In all
cases the division is strictly amitotic. In some cases a concentra-
tion of the chromatin occurs along lines parallel with the longer
axis of the meganucleus, giving the appearance of longitudinal
striations or thin delicate chromosomes with anything but the higher
magnifying powers. In some cases (Spirochona) these lines are
crowded together at' the narrowest part of the constriction, and
may have the appearance of a broad equatorial plate. In Spirochona

THE INFUSORIA

377

(Fig. 23) and Kentrochona we also find a clear globule of achromatin
substance at the poles, but there are no true linin fibrils. In most
cases the meganucleus in fission or gemmation divides by simple
constriction into two approximately equal parts, but in Opalinopsis
(Fig. 19) and Anoplophrya (Fig. 30) it divides into a number of
unequal parts, and in Ephelota (Fig. 20), Podophrya, and others a
number of pieces are constricted off from it, each of which gives
rise to the meganucleus of a bud.

The division of the micronucleus is always mitotic. The first
changes that are noticed are increase of size and the resolution of
the chromatic granule into a network of anastomosing fibrils. The
increase in size is usually considerable. In Colpidium, for example,
the diameter increases three- or four-fold (Hoyer). In Dendrocometes
the micronucleus increases from 2 p. to 10 /A in diameter.

0

Fio. 24.

Diagram to illustrate the structure and division of the nuclei of the Infusoria. 1, a micro-
nucleus in a state of rest, consisting of a spherule of chromatin in a clear vacuole ; 2, formation
of the spindle of linin fibrils, with a band of chromosomes on the equator ; 3, the chromatin
separated into two compact masses at the poles of the spindle ; 4, formation of the vacuole
round the chromatin, and dissipation of the spindle ; 5, a spherical meganucleus in a state
of rest ; 6, elongation of the meganucleus previous to division ; 7, constriction of the mega-
nucleus ; 8, division into two daughter meganuclei.

After the increase of the micronucleus in size is completed, a
clearly-defined spindle of linin fibrils appears and the chromatin
network breaks up into a number of small chromosomes arranged
in an equatorial plane (Fig. 24). The chromosomes are so small
and their number is so great that they can neither be accurately
counted nor their method of fission determined. It seems probable,
however, that the two parties which travel towards the poles are
exactly equal in number. No satisfactory accounts have yet been
given, in the division of the micronucleus, of structures correspond-
ing with the centrosomes of the karyokinetic figures of other cells,
and in many cases that have been very carefully investigated
centrosomes are certainly absent. It is one of the most striking
features, perhaps, of the nuclear phenomena of the Heterokaryota
that centrosomes do not occur. The two parties of chromosomes
travel with considerable rapidity to the poles of the spindles, and
there, in many cases, they become compressed into a tiny compact
mass, leaving the spindle between them free from chromatin. The

378

THE INFUSORIA

spindle is, in this condition, frequently very much elongated,
stretching more than half-way across the medulla. In Dendro-
cometes it is at this stage as much as 30 p in length (Fig. 31). The
spindle disappears suddenly and seems to be completely absorbed
by the cytoplasm immediately, or very soon after, it is disconnected
from the chromatin granules at the poles.

fev= m

THE NUCLEI OF OPALINA.

If the current views concerning the nuclei of Opalina are trustworthy,
this genus should no longer be regarded as a member of the Hetero-
karyota. Opalina possesses, according to Pfitzner and others, a large
number of meganuclei, but no micronuclei. Moreover, the meganuclei
divide by a typical process of mitosis. These views may possibly be
erroneous. Thin sections of Opalina that are suitably stained show, in
addition to the numerous meganuclei, a large number of small bodies
containing chromatin. These are probably
micronuclei (Fig. 25). The meganuclei divide
sometimes amitotically, and it is probable that
they always do so. The mitotic figures dis-
covered by Pfitzner are clearly seen in a large
number of sections examined, but they are
smaller than the meganuclei and are probably
formed by micronuclei which, as in other forms,
increase considerably in size before division.
The matter requires, however, further investi-
gation.

CONTRACTILE VACUOLES. — The contrac-
tile vacuoles occur in all Heterokaryota
except in Opalina, Opalinopsis, some of the
marine Hypotricha, and a few others. They
are simply spaces formed at some localised
spot or spots in the medulla by the accumu-
lotion of a fluid, and they discharge their con-
^w ?Vt large megan.udei tents to the exterior when they have reached

(Af) and the numerous minute , » . «• • />• mi /i • i

chromatin bodies (m), which a definite limit or size. Ihe fluid that ac-

are probably the micronuclei. i^-ii • 1111 j

(Original.) cumulates in these spaces is probably charged

with waste products of the metabolism

of protoplasm. Although the positions in which these vacuoles
appear are fairly constant for each individual, they have no
proper walls, and must not be regarded as definitely formed
organs. The number varies enormously in the group (1-100 or
more), and when there are more than three or four in any one
species the number may vary in the individual (Fig. 26). In some
of the large species the number of the contractile vacuoles increases
with the size and age of the individual, but in Nassula, Dendro-

FIG. 25.

THE INFUSORIA

379

FIG. 26.

cometes, and others which reach a considerable size there is never
more than one.

In the majority of cases the contractile vacuole is spherical in
shape and situated in the medulla. It slowly
expands (diastole) until its periphery comes in
contact with the pellicle at the surface, when
it instantaneously collapses (systole). In some
forms (Spirostomum, etc.) a long canal may be seen,
towards the close of diastole, to be connected
with the spherical vacuole. This appears to be
formed by the fusion of a row of small secondary
vacuoles stretching from the anterior to the
posterior end of the body. In Stentor the con-
tractile vacuole has a very elongated, rod-shaped
form (Fig. 44).

In the VORTICELLIDAE it is situated in the
neighbourhood of the vestibule, but instead of
opening directly into it when systole occurs, it
opens into a reservoir which is in communica-
tion with the vestibule. In Blepharocorys (Fig. 4)
and some other forms the contractile vacuole opens
into the passage which leads to the anus. In
Paranwecmm (Fig. 46, 3) and a great many other ^ ^act™
forms a series of six or more canals or spindle- oiigotnchous infusorian

. . T • with several contrac-

shaped secondary vacuoles appear in a radiating tile vacuoles. (After
form round the principal contractile vacuole, and *
may be seen to discharge their contents into the primary vacuole
immediately before its collapse.

There can be little doubt that the function of the contractile
vacuole is primarily the excretion of waste products, but by assisting
the osmosis of fresh water through the protoplasm it may be
regarded as being also respiratory in function. As shown by
A. G. Bourne, when anilin blue is added to the water in which the
animal lives, the contents of the contractile vacuoles are deeply
stained.

The systole of the contractile vacuole is not caused by any
active contraction on the part of the protoplasm of the medulla,
but, according to Btitschli, it is due to the physical attraction of
the small droplet of fluid to the mass of water at the periphery.
It is of the same general nature as the phenomenon of capillarity.
The action cannot take place until the vacuole has, by its diastole,
reached the periphery, and the drop of fluid is thereby brought
into contact with the surrounding medium.

The rapidity of the successive contractions of the contractile
vacuoles is variable. According to Rossbach it always increases
with a rise in temperature. In Euplotes cJiaran the intervals

380

THE INFUSORIA

between each contraction were 61 seconds at 5° C., and regularly
diminished to 23 seconds at 30° C. In Stylonychia they diminished
from 18 at 5° C. to 4 at 30° C.

DIGESTION. — The food of the Ciliata usually consists of minute
organisms such as Bacteria, other Infusoria, etc., or particles of
organic substance which are able to pass through the mouth into
the medulla. As they enter the medullary protoplasm they are
accompanied by a globule of water and give rise to the so-called
food vacuoles. The food vacuoles pass along a definite course
and ultimately reach the anus, or some position in the cortex
where a temporary anal aperture can be formed. If a Carchesium
(Fig. 27) be fed with finely - powdered food material that

Fio. 27.

Diagram of Carchesium to show the
course taken by the food vacuoles. 1,
the region of ingestion ; 2, of aggrega-
tion ; 3, of solution ; 4, ejection. M,
the meganucleus. (After Greenwood.)

Fio. 28.

Four stages in the food vacuole of a
Carchesium fed with white of egg and
Indian ink. A, immediately alter in-
gestion ; B, first phase of aggregation ;
C, second phase of aggregation ; D, just
before ejection. (After Greenwood.)

is stained, the following changes can be observed. Shortly
after ingestion the particles are aggregated into a lump at the
centre of the vacuole by the centripetal flow of a liquid from the
surrounding cytoplasm. A secretion of an acid into the vacuole
then occurs and the food particles undergo partial solution
(Fig. 28). In the next stage absorption of the dissolved food
into the protoplasm takes place, and then the vacuole, with the
undigested remnants, travels to the region of the vestibule, where
a temporary anus is formed for the discharge of its contents.

In the mouthless Opalina the food is probably absorbed in a
liquid form from the surrounding medium. In some of the
TRICHONYMPHIDAE solid food is entangled by the motionless cilia at
the posterior end of the body and then enveloped by the proto-
plasm in an amoeboid fashion.

THE INFUSORIA

REPRODUCTION. — In the simplest forms of INFUSORIA the mode
of reproduction in the motile phases of life is simple transverse
fission, but in the higher forms other methods of division occur
which are usually called longitudinal fission, simple gemmation,

Fio. 29.

Diagrams to illustrate the principal modes of division in the HETEROKARYOTA. 1, equal
transverse fission as in Paramoecium ; 2, unequal fission as in Stentor ; 3, longitudinal
fission as in Vorticella; 4, endogenous, unequal, and heteromorphic fission as in Tokophrya.
M, meganucleus ; m, micronucleus ; o, mouth; c.v., contractile vacuole ; G, geinmula ; Az,
adoral zone. (After Lang.)

multiple gemmation, and spore-formation respectively. All of these,
however, are probably modifications of the same essential process,
which consists in the division of the three elements of the body —
cytoplasm, meganucleus, and micronucleus — into two or more than
two parts.

In Paramoecium and Stylonychia, which may be taken as examples

382 THE INFUSORIA

of HOLOTRICHA and HYPOTRICHA respectively, fission is preceded
by the formation of a second mouth (Fig. 29, 1), and the growth of a
new set of cilia or cirri round and in the neighbourhood of this
second mouth, similar in size and arrangement to those in the
neighbourhood of the original mouth ; and by the division of the
contractile vacuole. In the next phase the micronucleus or micro-
nuclei enlarge, then elongate and show the characteristic features
of their mitotic division. Next, the meganucleus elongates and
becomes constricted in the middle. While these changes in the
nuclei are taking place, a constriction of the cortex appears at a
point which is approximately half-way down the longitudinal axis
of the body. The micronuclei, the meganucleus, and finally the
protoplasm of the body, then divide in succession, and the two
individuals that are formed separate and swim away. In the
process thus described the cortical protoplasm apparently leads the
way by the formation of new cilia and a new mouth. On the
other hand, the micronuclei have usually formed the mitotic figure
before actual constriction of the body is apparent. If the minute
structure of the meganucleus be examined in the earlier stages of
fission, it may be noticed that it also is not indifferent to the changes
going on elsewhere. It is therefore impossible to state with
certainty that either the nucleoplasm or the cytoplasm of the
organism initiates the process ; in fact, it seems probable in the
present state of our knowledge that the impulse to divide affects
all parts simultaneously.

In Spirostomum and Condylostoma the very much elongated
moniliform meganucleus is contracted into a short rod-like form
before fission occurs. In Stentor, too, fission is preceded by a
contraction of the long moniliform meganucleus (Figs. 44 and 29, 2)
into a thick spherical lump ; but the meganucleus again elongates
and divides transversely into two moniliform bands before the act of
fission actually takes place. In Oxytricha (Figs. 16, 17, 18) and
some other HYPOTRICHA the meganucleus during the active phases
of life is scattered in the form of small granules through the medulla.
Before fission takes place these granules collect together and fuse
to form a single lump. This consolidated nucleus then divides once
or twice, and fission of the whole body follows.

Fission is not, however, always preceded by the fusion of
scattered meganuclei or the contraction of elongated ones. In
Opalina the scattered meganuclei appear to be indifferent to the
division of the body, and in Opalinopsis (Fig. 19) and Anoplophrya
(Fig. 30) the meganucleus divides into fragments, one or more of
which become the meganuclei of the daughter individuals.

In Paramoecium and most of the HOLOTRICHA the transverse
fission results in the production of two equal individuals, but in
the transverse fission of Stentor and other Heterotricha the anterior

THE INFUSORIA

383

Fio. 30.

or oral extremity is decidedly smaller than the other. In Hoplito-
phrya the division is also unequal, but the smaller individual is at
the end usually regarded as the posterior end.
In Anoplophrya nodulata there is multiple transverse
fission (Fig. 20), the result being one large in-
dividual and four or five smaller ones. Similarly
in Opalinopsis the posterior end of the body gives
rise to a series of small individuals which constrict
off from the parent.

The mode of reproduction in Spirochona is very
remarkable. A large lump grows from the body
wall just behind the spiral membrane (Fig. 23),
and this increases until it reaches a size almost
as large as the parent form. Judging from ex-
ternal appearance alone, it might be considered
that this is a process of gemmation essentially
different from the transverse fission of the HOLO-
TRICHA, but the meganucleus and the micronuclei
divide equally during the growth of the so-called

j j.— , i i • Anoplophrya nodu-

bud, and no difference can be observed in size or lata, o. F. Muiier, from

quality between the nuclear portions that are dis- chaetaTexhfbiUn^'un-

tributed to the two resultant individuals. The j^al and^dhrisfon^of

process cannot therefore be separated from fission, the elongated mega-

. , ,. ., e ,1 . ,1 f nucleus (M, M) with-

notwithstanding the tact that tne manner 01 out previous concen.
growth of the parent antecedent to reproduction numerous Contractile
is very exceptional. In the VORTICELLINA the vacuoies. (After ciap.

J , ' . . n i • i and Lachmann.) xca

manner of reproduction is usually designated iso.
longitudinal fission. The external phenomena
begin with the division of the spiral zone into two equal spirals,
and proceed through the disc to the stalk, and may (in some of
the solitary forms) continue to the base of attachment, or (in the
colonial forms) be arrested before the attached end of the stalk is
reached. In the majority of the solitary Vorticellina the stalk does
not divide. The left daughter individual develops an aboral ring of
cilia and swims away, whilst the right daughter individual remains
with the parent stalk intact.

There is not any morphological distinction between the longi-
tudinal fission of the PERITRICHA and the transverse fission of the
HOLOTRICHA. It is very probable that, if there is any justification
at all for the comparison of the body axes of such simple forms of
life, the longitudinal axis of PERITRICHA is homologous with the
dorso-ventral axis of the HOLOTRICHA, and the fission is from a
morphological point of view a transverse fission.

The examples of unequal transverse fission which have been
quoted as occurring in HETEROTRICHA lead to the consideration of
an interesting modification of the process which occurs in the

384

THE INFUSORIA

ACINETARIA. The simple fission into two approximately equal
halves occurs in a few simple forms only in this class (Sphaeroplirya,
etc.); in others (some forms of Acineta, Tokophrya (Fig. 29, 4), etc.)

the smaller of the two segments is
enclosed in a pouch-like cavity of the
larger segment.

In Dendrocometes (Fig. 31) the difference
in size between the two segments is even
more pronounced. The three micronuclei
undergo their phases of mitosis preparatory
to division, in a plane at right angles to

Vertical section through Dendro- the g111 of tlle host to which the am'mal

cometes paradoxus, Stein, in an early is attached. The meganucleus becomes

stage of reproduction. The trans- i i j j ii, i u j

verlely striated curved line represents elongated and then sends out a broad

the first indication of the band of pseudopodial process in the same direction.

cilia of the future gemmula. The £ *

meganucleus (M) has begun to con- While these nuclear changes are taking

strict ; the three micronuclei (m) are ^lapp „ mirvprl trnnovprap.lv etristprl Vwinrl

in the final phase of their mitosis. Place> a curved, transvei seiy-striated band

appears in the protoplasm, which is con-
tinued after division of the nuclei into a complete circle embracing three
micronuclei and one meganucleus. The protoplasm enclosed by this band
is then detached from its surroundings and rotates slowly for a time by
means of an equatorial girdle of cilia. It then breaks through the body
wall of the parent and swims away. TMs remarkable ciliated daughter
segment may be called a "gemmula" (Fig. 86).

In Dendrosoma (Fig. 32)
several daughter segments en-
closed in incubatory pouches
are formed in different parts
of the branching body at the
same time, and these cannot be
regarded as essentially dis-

FIG. 32.

Dendrosoma radians, Ehrb. Size varies from
1-2 mm. in height, d, base of attachment; c,
ciliated gemmulae in their pouches ; e, smaller
bud-like bodies of doubtful significance. (After
Saville Kent.)

FIG. 33.

Free-swimming ciliated gem-
mula of Dendrosoma. a, mega-
nucleus ; 6, b, b, contractile
vacuoles. (After Saville Kent.)
x 600.

tinct in their nature or in their mode of formation from the
single internal daughter segment of Dendrocometes. The reproduc-

THE INFUSORIA 385

tion of Dendrosoma therefore appears to be a process of multiple,

internal, unequal fission. In several species of Ephelota and

others, not one hut several small daughter seg-

ments are formed simultaneously (Figs. 34 and

21) at the free extremity of the body, and

these are liberated when they have reached a

certain size.

In the literature of ACINETABIA the smaller
daughter segments receive the names "buds,"
"gemmulae," or "embryos," and the processes by
which they are formed are called internal or
external, multiple or simple, gemmation. Whilst

recognising the utility of retaining such a name as

gemmulae for them, it must not be forgotten that the for liberation. (From an
f ,. ,, TT , -, , original drawing and pre-

process of gemmation in the Heterokaryota is essen- paration by Dr. Ash-
tially the same as that of fission. worth.)

ENCYSTMENT AND SPORE-FORMATION. — There can be no doubt
that a very large number of the Infusoria have the power of
encystment. The encystment may be accompanied by reproduction,
a large number of small individuals being formed during the period
and escaping from the cyst wall at the end of it, or it may be
simply a resting-stage from which only one individual escapes. In
many CILIATA (Colpoda, Prorodon, etc.) both kinds of cysts may
occur in the same species, and it is difficult to draw any definite
line between them, but in the majority of species it seems probable
that the cysts are either purely resting cysts or reproductive cysts.

Encystment may be caused by the concentration of the salts in
water previous to drought, as proved experimentally by Cienkowsky ;
by the diminution in the food supply, as proved by Maupas for the
OXYTRICHINAE ; or, in the entozoic forms, by the change from their
natural habitat into fresh-water. Encystment is never, in any
Ciliata, a necessary sequence of conjugation. In the process of
encystment the cilia are withdrawn and the protoplasm of the body
contracted into a spherical or elliptical shape, while one or more
walls are secreted by the pellicle. The outer wall or ectocyst may
be soft and gelatinous as in certain Vorticellina, or it may be hard,
facetted, or thorned (Fig. 73). The inner walls or endocysts are
usually thin and membranous.

The resting cysts are capable of resisting the effects of dry air
for a considerable length of time. Nussbaum, for instance, found
that the cysts of Gastrostyla wrax were alive at the end of two
years, and Maupas successfully hatched out Gastrostyla steinii from
cysts that had remained dry in a watch-glass for twenty -two
months. Nussbaum, however, found that in twelve years all the
encysted Gastrostyla vorax were dead.

25

386

THE INFUSORIA

The method by which reproduction takes place in the repro-
ductive cysts is not known with certainty, but it is probable that
there is a rapid succession of simple fissions of the protoplasmic
contents of the cyst, leading to the production of numerous swarm-
spores, as is stated to be the case in Holophrya multifiliis (Fig. 36).

CONJUGATION. — A single indi-
vidual Ciliate Infusorian can pro-
duce a large number of generations
of daughter individuals by the pro-
cess of fission, but there is reason to
believe that the number is limited,

FIG. 35.

Cyst of Dileptus anser, O.F.M. ,
provided with an outer shell or
ectocyst and an inner mem-
brane (endocyst) attached to the
ectocyst at the poles. (After
Cienkowsky.)

FIG. 36.

Cyst of Holophrya midtiJUiis, Fouq.,
as found at the bottom of aquaria in
which fish affected with Holophrya are
living. From the cyst numerous cili-
ated swarm - spores are escaping.
(After Fouquet.) x about 75.

and that after a time the power of fission slackens and ulti-
mately ceases. Under normal conditions, however, the individuals
exhibit a tendency to conjugate after several generations have
been produced by fission, and if we are justified in regarding the
individuality of two conjugating INFUSORIA as the same after con-
jugation as before, it may be said that the result of conjugation is
a renewal and a stimulation of the powers of fission of the con-
jugating individuals. Although our knowledge is still far from
complete, it seems certain that a process of conjugation occurs in
all HETEROKARYOTA, and that this process is essential for the con-
tinuance of the vitality of the species.

There can be no doubt that the impulse to conjugation is in a
large number of cases periodic, the individuals of a swarm showing
for several days together no tendency to conjugation, and then
simultaneously collecting together in pairs and conjugating. The
cause of the impulse is obscure. Maupas expressed the opinion that
a diminution in the food-supply is the primary cause of the impulse,
and that individuals can be prevented from conjugating by increas-
ing the supply of food when the tendency first makes its appearance.

According to the researches of Maupas the epidemic of conjugation in
Stylonychia pustulata reaches its height after 175 fissions. This author
also states that conjugation can be prevented by a suitable increase in
the food supply, and that senile decay and death occur after 316 fissions.

THE INFUSORIA 387

On the other hand, Joukowsky has recently failed to induce conjugation
by hunger in Pleurotricha after experimenting for eight months and
reaching the 458th generation, and Calkins has cultivated Paramoecium
caudatum to the 620th generation, without conjugation, by changing the
food when the periods of depression set in.

There is some reason to believe that the onset of the epidemic of
conjugation in certain CILIATA. is associated with a material diminution
in size ; the largest specimens of a species having the power or vital
force to divide by fission, do not need the stimulus of conjugation for
further reproduction.

In the long series of varieties that the process of conjugation
presents in the HETEROKARYOTA, attention may be called to
three conditions which, when separated from the series, appear to
present essential differences. In most of the free-swimming ClLlATA
all the individuals of a swarm in which there is an epidemic of
conjugation are of the same size and structure, and it is probable
that any one individual can conjugate with any other. There is
no distinction of sex whatever.

In the conjugation of Spirochona two individuals apparently
identical, situated close to one another on the same gill of
Gammarus, bend towards each other and conjugate by their oral
discs. Subsequently one of the two individuals separates from the
gill and becomes absorbed (partially or wholly) by the other one,
and from that moment it ceases to exist as an individual. In this
case no external features of sexual differentiation have been
observed, and perhaps do not exist, between individuals that are
capable of conjugating with one another ; but after conjugation has
begun the important difference between the one that absorbs, which
has been compared to an ovum of the metazoa, and the one that is
absorbed, which has been compared to a spermatozoon, is exhibited
(cf. p. 393).

In the third case, as exhibited by Vorticella and some other
PERITRICHA, the difference between individuals that can conjugate
is well marked long before conjugation actually occurs (Figs. 43 and
76). The stalked form, which may be called the female individual,
is not capable of conjugating with another individual of the same
kind,1 nor, on the other hand, are the small free-swimming forms
that are periodically produced — the males — capable of conjugating
with one another. The only way in which conjugation can be
effected is by one female individual conjugating with one male
individual. In other words, the differentiation of sex appears to be
complete in the case of Vorticella and some other forms.

During the process of conjugation very important and complicated
changes occur in the nuclei of both individuals, and in all probability

1 It is possible that in some species a conjugation of the females may occur (see
Plate Ixxiii. Fig. 96 of Butschli's "Infusoria").

388

THE INFUSORIA

FIG. 37.

Diagram to illustrate the nuclear phenomena of the Ciliata, from the " Traite de Zoolog e
Concrete," based on the researches of Maupas. I, two individuals at the commencement of
conjugation, showing a single large meganucleus and a single small micronucleus. II, stage in
which the micronuclei have begun their mitosis. Ill, stage at the close of the first mitosis of
the micronuclei. IV, stage at the close of the second mitosis of the micronuclei. V, stage in
which there are four nuclei formed by the division of the micronucleus, and the meganucleus
is becoming irregular in outline. VI, stage in which three nuclei are undergoing degenerative
changes, and one — the sexual nucleus — is again dividing. VII, stage in which the sexual
nucleus has divided into a migratory and a stationary nucleus, and the migratory nucleus of
each individual has crossed into the cytoplasm of the other. VIII, stage in which the stationary
and migratory nuclei have come in contact with each other. IX, stage in which the cleavage
nucleus has been formed by the fusion of the migratory and stationary nuclei. The meganuclei
have now broken up into a number of small fragments. X, stage in which the individuals
have separated and the cleavage nucleus is undergoing its first mitosis. XI, the fragments
of the old meganuclei have entirely disappeared, and a new meganucleus and a new micro-
nucleus are forming from the daughter nuclei of the cleavage nucleus. XII, final stage with
a full-sized meganucleus and a micronucleus.

THE INFUSORIA

389

in the cytoplasm as well. For the elucidation of these changes it
is convenient to consider, in the first place, the phenomena that
have been observed in certain HOLOTRICHA (cf. Fig. 37). When
two individuals have effectively conjugated, the micronucleus of
each swells up and undergoes division by mitosis into two micro-
nuclei (II., III.). This is immediately followed by a division into
four (IV., V.). Of these four nuclei three degenerate and are
either absorbed or rejected
from the body (VI., and ,////.

Fig. 38). The remaining
one — which may be called
the sexual nucleus — under-
goes another division into
two nuclei. One of these
crosses the line of junction
of the conjugating in-
dividuals and enters the
cytoplasm of the other in-
dividual, and may be called
the migratory nucleus.
The other remains in the
cytoplasm of the parent,
and may be called the
stationary nucleus. Thus,
as a result of the divisions
of the original micro-
nucleus of each of the
conjugating individuals,
five nuclei are formed : three degenerate and disappear, one migrates,
and the remaining one is stationary. A fusion of the migratory
nucleus of one individual and the stationary nucleus of the other
then takes place to form the cleavage nucleus (VIII., IX.), and soon
after this has occurred the two individuals separate. The cleavage
nucleus soon divides into two (X.), and generally a second time
into four, or a third time into eight. Ultimately, however, one of
the halves of a division gives rise to the new meganucleus, and the
other to the micronucleus of a daughter individual. The new
meganucleus can therefore be traced back to its origin from micro-
nuclear elements, and to this there is no exception. The mega-
nucleus of a conjugating individual never gives rise to the mega-
nucleus of an individual that has been released from conjugation.

Returning to the earlier stages of conjugation, and tracing the
fate of the original meganuclei, we find that, apart from minor
changes in the arrangement of the chromatin network, the
meganuclei do not seem to be affected by the union of the two
individuals. Later on, however, they become irregular in outline

Fio. 38.

A stage in conjugation of Colpidium colpoda just before
the formation of the migratory and stationary micro-
nuclei. M, meganucleus ; m\, the sexual nucleus ; m^,
the three nuclei undergoing degeneration. (After
Hoyer.)

390

THE INFUSORIA

(III., V.), break up into lumps (VI.), into smaller droplets, and
ultimately disintegrate (X.) and disappear (XL).

The changes which take place in the cytoplasm during conjuga-
tion have not yet been followed in detail. There can be little
doubt that an interchange of molecules of cytoplasm between the
two individuals does occur, but it is quite impossible to tell
whether the mixing of the two cytoplasms is or is not complete.

In the accounts given of the conjugation of the Ciliata, it is stated
that the meganucleus plays a perfectly passive role until its disintegration
begins.

In Spirochona the meganuclei fuse during conjugation ; and in
Dendrocometes the meganuclei come in contact during conjugation, but
subsequently separate (Fig. 39).

FIG.

Reconstruction of a series of sections through a pair of conjugating Dendrocometes, showing
a temporary fusion of the two meganuclei (M ), at the conclusion of the process. MN, the
new meganucleus ; m, the three new micronuclei. (Original.)

In those species which normally possess more than one micro-
nucleus the process is rather more complicated.

In Paramoecium aurelia the two micronuclei which are normally
present in each individual divide twice, giving rise to eight nuclei,
of which number seven degenerate and one remains as the sexual
nucleus. After the conjugation of the migratory and stationary
nuclei, the cleavage nucleus of each individual divides twice, and
of the four nuclei thus formed, two directly give rise to meganuclei
and the remaining two divide again to give rise to the two micro-
nuclei in each of the daughter individuals formed by the first fission.

In Dendrocometes there are usually three micronuclei in each
individual. At the commencement of conjugation all three micro-
nuclei enlarge and undergo mitosis (Fig. 40), but not simultaneously.
Of the six nuclei thus formed, five degenerate and one passes down
the junction and forms the sexual nucleus.

In Bursaria truncatella there are, according to Prowazek, normally
1 6-.1 8 micronuclei in each individual, which give rise to no less than

THE INFUSORIA

66-78 descendant nuclei during conjugation, but they all degenerate
except one, which alone forms the sexual nucleus (Fig. 60).

Fro. 40.

Reconstruction of a series of sections through a pair of Dendrocometes at the beginning of
conjugation. M, the ineganucleus. m points to one of the micronuclei in the process of
mitosis. One of the three micronuclei in each individual has not begun to divide, but it is
much larger than the micronuclei of individuals that are not conjugating. (Original.)

In the VORTICELLIDAE there is a further modification of the
process. The micronucleus of the female divides twice, to form

A'

A

B

B

Fio. 41.

Diagram I., to illustrate the nuclear
changes during conjugation of two Holo-
trichans, A and B. M, ineganucleus ; TO,
micronucleus ; N, migratory nucleus ; S,
stationary nucleus ; C, cleavage nucleus ;
M', the ineganucleus, and TO', the micro-
nucleus of the individuals, A' A', B' B1, formed
by the first fission after conjugation.

Fio. 42.

Diagram II., to illustrate the nuclear
changes during the conjugation of a female
(A) and a male (B) Votlcella, M, meganucleus ;
TO, micronucleus of A and B; S, station-
ary sexual nucleus ; N, migratory sexual
nucleus ; c, cleavage nucleus ; M', the
ineganucleus formed by the fusion of three
nuclei; and m', the micronucleus of the
regenerated female A'.

four nuclei, and of these, three degenerate ; the micronucleus of
the male, on the other hand, divides three times, to form eight
nuclei, of which seven degenerate (Fig. 43). Only one cleavage

392

THE INFUSORIA

nucleus is formed, namely, the one in the female individual. The
male shrivels and dies. The cleavage nucleus divides twice, and

FIG. 43.

Two stages in the conjugation of
Vorticella monilata. In A the
micronucleus of the female lias
given rise to four nuclei, the
micronucleus of the male to eight
nuclei ; the meganuclei (M) in both
have disintegrated. In B, which
represents a later stage, the
cleavage nucleus has been formed
in the female ; in the male the
migratory and stationary sexual
are close together, but do not fuse.
(Diagrammatic drawings after
Maupas. The ciliated discs are
actually retracted during these
stages.)

three of the nuclei enlarge and subsequently fuse to form the new
meganucleus, whilst the remaining one forms the new micronucleus.

REGENERATION. — Several
series of experiments have now
been recorded which prove that
the Ciliata possess very con-
siderable powers of the re-
generation of lost parts. If,
for example, a Stentor be cut
into two parts transversely,
the upper part will, in a little
while, close up the wound, and
eventually form a base similar
in all essential respects to the
parts that are lost ; the lower
portion will, on the other hand,
produce a new spiral disc and
a new mouth. Thus, as a result
of this artificial section of a single individual,
two complete individuals are produced.
Similarly, sections of the body into three,
four, or five pieces may be made, which re-
generate and give rise to new and complete
individuals. There are limits, however, to

FIG. 44.

Stentor coeruleus, Ehrb. M, the long moniliform mega-
nucleus; c.v, the contractile vacuole. If the animal is cut
through in the plane a-b, both portions will survive and
regenerate lost parts ; if it be cut in the plane c-d, only the
lower part containing the meganucleus will survive. (The
figure of the Stentor after Saville Kent.)

this power of regeneration. If a section be made through a
Stentor in the plane of the line c-d in Fig. 44, it will be found

THE INFUSORIA 393

that the segment containing the meganucleus will regenerate the
lost part; the segment which contains no portion of the mega-
nucleus, however, will degenerate and die. Further experiments
that have been made on Stentor, on Stylonychia, and other forms
prove that a portion of the meganucleus plays an essential part in
the regeneration of the segments, and that in all cases the detached
parts of an infusorian that are devoid of meganucleus, however
large they may be, degenerate and die without repairing their
injuries. The nucleated fragments, on the other hand, are capable
of regenerating lost parts even when they are exceedingly small,
but a limit of size may be reached, which in the case of Stentor is
said to be 80 p. in diameter (Lillie), below which even nucleated
fragments die.

There is very little evidence upon the history of the micronuclei in
these experiments. Le Dantec, however, states that segments which
contain no micronuclei are capable of regenerating lost parts, and that
in such cases a new micronucleus is formed by the meganucleus.

THE MORPHOLOGY OF THE HETEROKARYOTE BODY.

The generally accepted view that the body of one of these
animals is strictly unicellular requires some modification unless our
definition of an animal cell is to be widely extended. In the Meta-
zoan body we can recognise two classes of cells — the somatic cells,
which perform the general functions of the body ; and the germinal
cells, which are alone concerned with reproduction. We can also
recognise two classes of nuclei in the same manner — the somatic
nuclei and the germinal nuclei. In the Metazoan body there is
a large number of somatic cells, and each of them contains, as a
general rule, a single somatic nucleus, and similarly each of the
many germinal cells contains, usually, a single germinal nucleus.

Many instances could be quoted (striated muscle, nerve fibres),
however, in which the cell outlines of both somatic and germinal
cells are ill-defined or absent, so that the tissues become indis-
tinguishable from multinuclear plasmodia. There can be no reason,
however, for calling such tissues unicellular tissues. The actual
number of cells composing the Metazoan body varies enormously,
and it is not inconceivable that an animal may have existed
(Fig. A) with only one somatic cell and one or two germinal cells,
and for protection the germinal cells (TO, m) might be within instead
of outside the larger somatic cell (M).1

1 Parallel examples of this may be found in the spermatogenesis
of Spongilla, Helix, Cossus, etc., in which the germinal cells are within
the blastophoral cell.

394 THE INFUSORIA

If, however, in such an animal the limits of somatic and germinal
cytoplasm were indistinguishable (Fig. B), we should have an
organism precisely similar in its essential features to one of the
Heterokaryota, and just as the hypothetical form is strictly
bicellular or tricellular, so is the Heterokaryote, strictly speaking,
not unicellular, but bicellular or tricellular, etc., according to the
number of micronuclei it possesses.

The matter is, however, to a certain extent a question of
nomenclature. If it is considered to be desirable to include in the
term, "cell," everything that is enclosed by the outline of a cyto-
plasmic unit, then the Heterokaryota may be called unicellular ;
but the definition of a cell must be extended so as to include
examples in which the cytoplasm includes nuclei of two or more
distinct characters.

The differences between the meganucleus and the micronucleus
in the Heterokaryota are very pronounced.

PIG. A. Fio. B.

The meganucleus is undoubtedly somatic in function. The
experiments mentioned on p. 392 prove that it is essential for the
process of the repair of injuries and for the restoration of parts
that have been lost; the changes in the structure of its granules
observed during assimilation and starvation point to its important
relations with the processes of digestion, whilst the changes in
its shape and position, during the somatic life of the individual,
indicate its continued functional activity during this period.

Speaking generally of the meganucleus of the Heterokaryotes,
it may be remarked that, as compared with other nuclei, it exhibits
an extraordinary variety of form. It may be spherical, oval, band-
like, moniliform, dumb-bell shaped, double, or scattered in numerous
small fragments.

The exact meaning of this may be obscure, but it is quite
consistent with the facts to believe that its peculiar shapes are
associated with the important somatic functions, over which it
exercises some essential control.

Whilst it is thus clear that the meganucleus is somatic in
function, it is none the less evident that the micronucleus is not.

THE INFUSORIA 395

During the whole of the somatic life, that is to say, between the acts
of fission and conjugation, the micronuclei remain extremely small,
the chromatin being concentrated into an extremely minute granule,
and there can be little doubt that they are in a condition of
rest.

During conjugation, however, the relative activity of the two
nuclei is reversed. The micronuclei enlarge, divide by mitosis, and
show other signs of extreme activity. It is the products of the
division of micronuclei alone that fuse to form the cleavage nuclei.
The meganuclei, on the other hand, degenerate and disappear.
The evidence, therefore, is conclusive that the meganucleus is a
somatic nucleus, and may be compared with the nuclei of the cells
of the body of a Metazoon, and that the micronucleus is a sexual
nucleus, and can be only compared with the nuclei of the sexual
cells of the Metazoon.

There is very little evidence, however, that there is allocated
to each micronucleus in the Infusorian's body a specialised part of
the cytoplasm, as there is in the Metazoon. There is, in other
words, evidence of a sexual nucleus, but very little evidence of
sexual cytoplasm. If we assume that such sexual cytoplasm does
exist, and that during the act of conjugation the sexual cytoplasm
of the two individuals mingles, the parallelism between the sexual
act of the Infusoria and that of the Metazoa is established.

But without making any assumption whatever, it is clearly
erroneous to compare the conjugation of two Infusorians with the
conjugation of an ovum and a spermatozoon. The degeneration of
the meganucleus after or during conjugation clearly proves that
the Infusorian is something more than a mere sexual cell or gamete.
It is only a part, and a very small part too, of the whole body of
the Infusorian that functionally conjugates, the remainder is only
accessory to the act. It is therefore only misleading to call the
stalked Vorticella a megagamete and the free-swimming individual
that becomes attached to it a microgamete. These individuals
have all the essential features of female and male individuals, and
the act that they perform is essentially an act comparable to the
copulation of the Metazoa. Similarly, the conjugating individuals of
the Holotricha ought not to be called Isogametes, but hermaphrodite
individuals.

An important and interesting question then arises as to the
individuality of the Infusoria before and after conjugation. The
destruction of the old somatic nucleus during conjugation is proved,
but there is also evidence of a less satisfactory nature that the
somatic cytoplasm undergoes regeneration after the act. If it be
assumed that the old somatic cytoplasm is gradually replaced by
the conjoint sexual cytoplasm of the two conjugates, then the
individuality of the Infusorian before and after conjugation is not

396 THE INFUSORIA

identical. It is clear that there is partial somatic death during
conjugation ; it is not clear, however, that there is complete somatic
death. It is to the elucidation of this important question that we
may look with confidence to future investigations.

CLASS CILIATA, EHRB.
ORDER HOLOTRICHA.

Examples of a Genus.

Sub-Order Gymnostomata. Prorodon.
Sub-Order Hymenostomata. Paramoecium.

ORDER HETEROTRICHA.

Sub-Order Polytricha. Stentor.

Sub-Order Oligotricha. Ophryoscolex.

ORDER HYPOTRICHA. Stylonychia.

ORDER PERITRICHA. Vorticella.

The Ciliata may be most conveniently divided into four orders —
the HOLOTRICHA, the HETEROTRICHA, the HYPOTRICHA, and the
PERITRICHA. Of these orders the HOLOTRICHA undoubtedly con-
tain those genera which are the most primitive in their anatomical
characters, the other three orders contain genera which have
probably reached their present condition on independent lines of
evolution from a common holotrichous ancestor.

ORDER Holotricha, Stein.

The order HOLOTRICHA includes those free-swimming Ciliata in
which the cilia are all of approximately equal length and thickness.
There are never any structures of the nature of cirri.

The order is divided into two sub-orders — (l)the GYMNOSTOMATA,
in which the mouth is closed in the intervals between the acts of
the ingestion of food ; and (2) the HYMENOSTOMATA, in which the
mouth is always open and provided with an undulating membrane.

SUB-ORDEII GYMNOSTOMATA, Biitschli.

The GYMNOSTOMATA are usually of small size, rarely exceeding ^ mm.
in length. Several of the genera (Holophrya, Enchelys, etc.) occur both in
the sea and in the fresh-water, others are found only in fresh-water (Pro-
rodon, Lacrymaria, Didinium, etc.), others only in sea-water (Stephanopogon,
Onychodactylus), and others are parasitic (Biitschlia in the stomach of
Ruminants).

In the more primitive forms (Holophrya, Enchelys) the mouth is a
simple passage from the medulla to the exterior, situated at the anterior

THE INFUSORIA

397

extremity of the body. In several forms the passage is kept open for the
greater part of its length by a palisade arrangement of stiff rods commonly
called the pharynx, but the mouth itself can be closed by the cortex
contracting over the anterior end of the pharynx (Prorodon, Coleps).

The position of the mouth is by no means con-
stant in the group. In Spathidium (Fig. 45) it is
somewhat elongated, and situated just behind the
anterior end of the body.

In Nassula it is situated at a distance of about one-
third of the length from the pointed anterior end of
the body.

In Dileptus and Tradielius (Fig. 7) there is a long
narrow lobe in front of the mouth.

The cilia are, in the most primitive forms (Holo-
phrya, etc.), evenly distributed over the surfaces of the
body j in some of these, however, the cilia which are .d^

arranged in a circlet round the mouth are a trifle like mouth above.tnenu-

i j ,1 . i / r . \ , , , i_ , i dens in the centre, and

longer and thicker (Lacrymana) than those on the the contractile vacuole

general surface. In the larger forms it may be ob- ^an (AfterButsc111'-)
served that the cilia are arranged in parallel rows
running longitudinally down the body or slightly curved like the rifling
of a firearm. In Didinium the cilia are confined to two fine horizontal

Fio. 45.
Spathidium lieber-

Fio. 46.

1, Surface view of a Holotrichous Ciliate, showing the disposition of the cilia in longitudinal
rows. 2, diagrammatic optical section of the same, showing all structures except the contractile
vacuoles ; a, meganucleus ; b, micronucleus ; c, cortex ; D, pellicle ; E, medulla ; /, cilia ;
g, trichocysts ; h, filaments ejected from the trichocysts ; i, mouth ; k, drop of water contain-
ing food particles about to sink into the medulla and form a food vacuole ; I, m, n, o, food
vacuoles, the successive order of their formation corresponding to the alphabetical sequence of
the letters ; p, pharynx. 3, outline of a Paramoecium to show the form and position of the
contractile vacuoles. 4-7, successive stages in the formation of the contractile vacuoles.
(From Lankester.)

bands, and in the parasitic Biitschlia and others the cilia occur in irregular
ridges and tufts.

398

In the remarkable genus Adinobolus there are a number of retractile
processes called the tentacles projecting in a radiating manner from the
body-wall, which give the animal a superficial resemblance to a Heliozoon
(Fig 48).

In Ileonema there is a single flagellate process at the anterior end of
the body which is capable of being completely withdrawn (Fig. 49).

Nearly all the Gymnostomata are provided with trichocysts. They
are situated either in special aggregations round the mouth, in which case
they are regarded as weapons of offence ; or scattered over the general
surface of the body, in which case they are regarded as weapons of
defence.

The meganucleus is frequently spherical or oval in shape, but it is
sometimes elongated, horse-shoe-shaped, moniliform, jointed, segmented, or
fragmented. The micronucleus of a considerable number of genera has not
yet been discovered, but in others there can be no doubt of the existence
of one (Chilodori) or more (Dileptus) micronuclei.

The genera of Gymnostomata are divided into families by
Schewiakoff as follows : —

Family HOLOPHRYINA, Perty. Holophrya, Ehrb. Of very simple
structure, with a terminal mouth provided with only a very rudimentary
pharyngeal apparatus. They form spherical cysts surrounded by a
gelatinous case in which an enormous number of young are produced by
rapid and repeated fissions (Figs. 36 and 47). G'4.1
Freshwater and marine, sometimes parasitic on fresh-
water fish. Urotricha, Clap, and L. Exceedingly
minute forms distinguished by the presence of a single
long straight bristle at the posterior end. 0'04.
Freshwater. Enchelys, Hill. Anterior and posterior
ends somewhat attenuated, but in other respects
similar to preceding genera. Well - developed
trichocysts. *-02-'2. Freshwater and marine.
Spathidium, Duj. Body flask -shaped. Mouth
ventral at the anterior end, long and slit -shaped.
0-4. Freshwater. (Fig. 45.) Cranotheridium., Schew.
With an elaborate pharyngeal armature. Numerous
micronuclei and a single meganucleus. 0'17.
Freshwater. Lagynus, Quenn. Bottle-shaped, with
a pharynx surrounded by numerous trichocysts.
mingUcondiUon.ree"2,W1eu- 0'18. Marine and freshwater. Trachelophyllum,
cysted condition with pro- Clap, and L. Similar to the preceding genus, but
toplasm undergoing its . , x, , , ,.,,, ' , , .

first transverse fission, a, with the body a little more flattened. 0'2. Marine
tractne^acuoies6' &x 120' and freshwater. Lacrymaria, Ehrb. Elongated,
extremely contractile forms. Anterior end shaped
like a bottle cork and surrounded by four or five bands of long cilia. 0'8.
Freshwater and marine. Trachelocerca, Ehrb. Very elongated and
contractile forms. Mouth surrounded by four lappets or lobes. Some-

1 These figures refer to the average length of the genera in millimetres.

ct'

FIG. 47.
Holophrya multiJUiis,

THE INFUSORIA

399

times reach a total length of 3 mm. Marine. Prorodon, Ehrb.
Usually spherical in form, with a well -developed pharyngeal armature.
1 mm. Freshwater. (Fig. 8.) Perispira, Stein. Bands of cilia arranged
in a spiral manner. 0'05. Stagnant freshwater. Chaenia, Quenn. An
elongated and contractile form with a special group of long cilia at the
anterior attenuated extremity. 0'25. Marine.

Family ACTINOBOLINA, Stein. Actinobolus, Stein (Fig. 48). Spherical
in shape, provided with a uniform covering of long cilia. The most
remarkable feature of this genus is the power they possess of protruding
a considerable number of long, needle-shaped protoplasmic processes or
tentacles, each armed at its extremity with a large trichocyst. O'l.

Fid. 48

Actinobolus radians, Stein, with the peculiar tentacles (*, t)
fully extended. Each tentacle bears at its extremity a tricho-
cyst. m, mouth ; M, meganncleus ; c.v, contractile vacuole ;
c, c, cluster of cilia at the insertion of the tentacles. (After
Schewiakoff.) x 400.

Fio. 49.

Ileonema dispar, Stokes.
M, meganucleus ; o,
mouth ; a.p, anterior
prehensile appendage ;
c.r, contractile vacuole.
(After Schewiakoff.)
x 300.

Freshwater. Ileonema, Stokes. Flask -shaped, with a long prehensile
appendage springing from the oral extremity (Fig. 49). 0'2. Freshwater.

Family COLEPINA, Ehrb. Playiopogon, Stein. Without carapace.
Very small. Freshwater. Coleps, Nitzsch. Body covered by a compli-
cated carapace (Fig. 5). 0'05. Freshwater. Tiarina, Bergh. Similar to
the above, but with a pointed posterior extremity. Marine. Stephanopogon,
Entz. Slightly elongated forms, flattened on ventral side, with a large
horse-shoe meganucleus. 0-07. Marine.

Family CYCLODININA, Stein. Dinophrya, Butschli. Cylindrical in
form, with a pointed posterior extremity. O'l. Freshwater. Didinium,
Stein (Fig. 74). Cylindrical in form, with a conical peristome. Cilia
restricted to a few circular bands. Mouth capable of extraordinary
dilatation. 0'2. Freshwater. Mesodinium, Stein. Cilia reduced to a
single band, very long and strong. 0'04. Marine and freshwater.

400

THE INFUSORIA

Family PROROTRICHINA, Biitsclili. Biitschlia, Schuberg. Very minute
cilia covering the general surface of the body, but a special perioral
crown of longer cilia, and a tuft of the same at the posterior extremity.
0'06. Rumen of Ruminants. The genera Blepharocodon, Bkpharopros-
thium, and Blepharosphaera described by Bundle from the coecum of the
horse are perhaps members of this family.

Family AMPHILEPTINA, Biitschli. Amphileptus, Clap, and L. The
anterior end pointed, and on the ventral side of this a long slit -like
mouth. Meganucleus in two or four pieces. 0'2. Marine, freshwater,
and in infusions. Lionotus, Wrzs. Similar to above, but rather more
elongated and flattened. 0'4. Marine and freshwater. Loxophyllum,
Duj. Similar to above, with the body more flattened and
contractile. 0'04. Marine and freshwater. Loxodes,
Ehrb. A creeping, spindle-shaped form, with several
meganuclei and micronuclei. 0'5. Freshwater.

Family TRACHELINA, Stein. Trachelius, Clap, and L.
(Fig. 7). Spherical in form, with a short proboscis in
front of the round mouth. O4. Freshwater. Dileptus,
Duj. (Fig. 50). Very elongated and contractile, with a
long proboscis armed with trichocysts in front of the
round mouth. Meganucleus moniliform. 1 mm. Marine
and freshwater.

Family NASSULINA, Biitschli. Nassula, Ehrb. Oval
forms with a long,

complicated pharyngeal >;t: ..-,

armature. Mouth on
the ventral side, a short
distance from the an-
terior end. Frequently
red, blue, or brown in
colour. 0'3. Fresh-
water and marine.

Family CHLAMYDO-
DONTA, Stein. Ortho-
don, Gruber. Cilia on
ventral side much
longer than on the
dorsal side. Mouth on
the right side. 0'26.
Marine and freshwater.
Chilodon, Ehrb. Oval in
outline. Strongly com-

c, c, trichocysts on pressed dorso-ventrally.

the ventral side of 7. _ Tr . . - . „, , , , _,. ,

the proboscis; d, 0'3. Very common in imusions. (JMamydoaon, Jiihrb.,

e> O'l 2, marine ; Scaphidiodon, Stein, O'l, marine ;
Phascolodon, Stein, 0'09, freshwater; and Opisthodon,
Stein, O'l 8, freshwater, are all closely related to Chilodon.

Family DYSTERINA, Clap, and L. Aegyria, Clap, and L. Body
usually ventrally folded. Cilia apparently confined to the ventral side.

o

c.v

FIG. 50.

Dileptus anser,
O.F.M. (-Amphi-
leptus gigas of Cla-
parede and Lach-
mann). b, b, con-
tractile vacuoles ;

a food vacuole
mouth, x 100.

ta—

Fio. 51.

Dysteria armata, Huxley, o, mouth ; M,
meganucleus ; TO, micronucleus ; c.v, c.v,
four contractile vacuoles ; eg, anal cirri ;
to, caudal appendage. ( After Schewiakoff.)
X 400.

THE INFUSORIA 401

0'15. Marine. Dysteria, Huxley (Fig. 51). Body somewhat resembling
a mussel in shape, with a very restricted ventral side which alone bears
cilia. There is a remarkable caudal appendage on the ventral side.
The dorsal side is smooth and ribbed. 0*15. Marine and freshwater.
Trochilia, Duj. 0'035. Freshwater and marine. Dysteropsis, Eoux.
Lacustrine.

Family ONYCHODACTYLINA, Entz. Onychodactylus, Entz. The body
bears at the posterior end a little conical appendage in the form of a tail,
at the extremity of which is the anus. The colour is yellow or blue.
0'2. Marine.

SOB-OKDER HYMENOSTOMATA, Delage.

The HYMENOSTOMATA include a large number of forms that occur
in infusions such as Loxocephalus, Colpidium, and Colpoda, from which the
name of the Class Infusoria was derived. Some of them are internal
parasites such as the OPALININA and ISOTRICHINA. Others are free-
swimming in pure water. They vary in size from the minute Cyclidium,
•03 mm., and Loxocephalus, '06 mm., to the elongated parasite Discophrya,
which is sometimes 2 mm. in length.

The mouth is in some cases at the anterior extremity of the body,
but more usually it is situated near the middle of one side. In such
forms as Isotricha it is doubtful which end of the body is correctly called
anterior. According to Biitschli and others the mouth is situated at the
posterior end, and the animal swims with the anterior end foremost.
Others consider that the mouth is at the anterior end, and that the animal
habitually swims backwards.

The mouth is usually situated at the bottom of an elongated, gutter-
like peristomial depression, and opens into a short oesophageal tube.
This tube, however, is never supported by a palisade of rods. In many
forms, and perhaps in all of them, there is a small undulating membrane
at the margin of the mouth — hence the name Hymenostomata. Some-
times there is in addition to this one or two very delicate membranes
(Pleuronema) at the margins of the peristomium which it is convenient to
distinguish as the lips (Fig. 52). Trichocysts are usually present. There
is generally a single spherical or oval meganucleus accompanied by one
or two micronuclei. In Frontonia there are several micronuclei. In
Anoplophrya (Fig. 30) there is an elongated meganucleus and in Opalinopsis
(Fig. 55) an irregular band-like meganucleus at first, which in the older
forms breaks up into a number of fragments. In Opalina there are several
spherical meganuclei, and probably a greater number of micronuclei
(Fig. 25).

Reproduction is effected by simple transverse fission. In Leucophrys
there is a resting stage during which the animal becomes spherical in
shape, but does not secrete an envelope. During this stage the body
divides into thirty -two small individuals. In Oj)hryoglena, Colpoda,
and Glaucoma cysts are formed. The kidney -shaped cysts of Para-
moecium have recently been figured by Lindner. The body of Opalina,
after it has reached a certain stage of growth, divides by fission several
times, until the fragments contain only two or three nuclei. Each

26

THE INFUSORIA

fragment then becomes encased in a spherical cyst. This is passed into
the water, and if it is then swallowed by a tadpole, gives rise to a
uninucleated spore which absorbs nourishment and grows. As it grows
the nucleus divides, and so the large inultinucleate form from which
it sprang is reattained (Figs. 53 and 54).

The HYMENOSTOMATA are arranged by Schewiakoff as follows : —
Family CHILIFERA, Butschli. Blepharostoma, Schew. With very
long peribuccal cilia. '015. Freshwater. Dichilum, Schew. With right
and left lips, the latter rudimentary. 0'03. Freshwater. Australia.
Trichospira, Roux. Freshwater. Dallasia, Stokes. Dorsal side concave,
ventral side convex. Very large mouth, just behind the anterior extremity.
Two undulating membranes. Swims on the concave dorsal side. O'l 4.
Freshwater. Plagiocampa, Schew. A lip on the left side only. A
border of labial cilia on the right. 0-04. Freshwater. Australia.
Uronema, Duj. Oval in form, slightly compressed. Convex on the
dorsal side. Flat on the ventral side, with an excavation in the
buccal region. Provided with a long caudal cilium. 0'07. Freshwater.
Stegochilum, Schew. Pharynx absent. Well-developed labial membrane.
0'07. Freshwater. Australia. Cryptochilum, Schew. Leucophrys, Ehrb.
Body compressed. Provided with a large, tongue -shaped, undulating
membrane. 0'25. Freshwater. Leucophrydium, Roux. Monochilum,
Schew. In the form of an elongated cylinder. Loxocephalus, Kent.
Undulating membrane doubtful. A single long cilium at posterior end,
also a row of specially long cilia on the right side. 0'05. Freshwater
and in infusions. Chasmatostoma, Engelmann. Kidney-shaped. 0'06.
Freshwater. Glaucoma, Ehrb. Oval in form, but slightly flattened.
Cilia evenly distributed. O'l. Freshwater, but principally found in
infusions. Urozona, Schew. Only the middle part of the body furnished
with cilia, which form a thick band encircling the body. 0'03. Fresh-
water. Colpidium, Stein. Oval or kidney-shaped. A large mouth
situated some distance behind the anterior extremity on the ventral side
of the body. Cilia evenly distributed. O'l 2. This genus and the next
(Colpoda) very common in freshwater infusions. Colpidium also occurs
in marine infusions. Colpoda, Miiller. Similar to Colpidium, but more
definitely kidney-shaped. The twist in the rows of cilia at the anterior
end is from left to right, the opposite of that in Colpidium. O'l. Very
common in hay infusions. Frontonia, Clap, and L. Large cylindrical
bodies or pointed posteriorly. On the right border of the mouth there
is a ciliated stripe, free from trichocysts. Colourless or green with
Zoochlorellae, sometimes provided with black or brown pigment. 0'35.
Freshwater and marine. Disematostoma, Lauterb. Philaster, Fabre Dom.
Ophryoglena, Clap, and L. 0'5. Freshwater. Blepharocorys, Bundle.
Coecum of the horse.

Family MICROTHORACINA, Wrzesniowski. Cinetochilum, Perty. This
animal appears to swim upside down. During progression the extremity
which bears the mouth is posterior. It is provided with two vibrating
lips, of which the right is larger than the left. 0'04. Freshwater.
Microthorax, Engelmann. The mouth turned more to the right side than
in the preceding genus. 0'06. Freshwater. Trichorhynchus, Balb. One

THE INFUSORIA

403

end is drawn out into a conical papilla armed with long cilia. Biitschli
regards this end as posterior. 0'04. Freshwater. Tuamotu. Ptycho-
stomum, Stein. O'l. Occurs in the intestine of Oligochaeta. Ancystrum,
Maupas. Ovoid in form, with a series of long cilia on the ventral border.
0'07. In the pallial cavity of marine Pelecypoda.

Family PARAMOECINA, Duj. Paramoecium, Stein. There is a
minute undulating membrane on the dorsal side of the pharynx. Tricho-
cysts tisually occur over the whole surface of the body. One or two con-
tractile vacuoles. One or two micronuclei. Up to 0'25 in length. Very
common. Freshwater and marine. (Fig. 46.)

Family UROCENTRINA, Clap, and L. Urocentrum, Nitzsch. The
ciliation of the body reduced to two broad zones. The peristome extends

from the posterior edge of
the anterior zone to the
hind end of the body. O'l.
Marine and freshwater.

u.m.

FIG. 52.

Pleuronema chrysalis, O.F.M. M, meganucleus ; m,
micronucleus ; u.m, the large right undulating lip ; /, F,
food particles ; c.v, contractile vacuole. (After Schewia-
koff.) x 400.

Fio. 53.

Opalina ranarum, Purkinje.
a, a, the meganuclei. (From
Lankester, after Zeller.) x 100.

Family PLEORONEMIXA, Biitschli. Lembadion, Perty. The peri-
stome is a deep groove extending from the anterior end of the body almost
to the posterior. It is covered by two large undulating lips. A small
undulating membrane also occurs on the right side of the peristomial
groove. Pleuronema, Duj. (Fig. 52). A very large peristome with a
large right undulating lip. Springing movement. 0'03. Marine and
freshwater. Lembiis, Cohn. An elongated form with two undulating lips.
O'l. Marine infusions. Cyclidium, Clap, and L. Very similar to Pleuro-
nema, but smaller. 0'03. Freshwater and marine. Cristigera, Roux.
Freshwater. Pleurocoptes, Wallengren, occurs on Hydractinia.

Family ISOTRICHINA, Biitschli. Isotricha, Stein. Spherical forms
with a mouth situated at the posterior (1) end. A well-marked anus
situated anteriorly. Numerous minute contractile vacuoles scattered
through the protoplasm. O'l 6. Rumen of the Artiodactyla. Dasy-
tricha, 0. Schuberg. No anus. Lines of cilia rather more spirally
arranged than in Isotricha. O'l. Rumen of Artiodactyla. Paraisotricha,
Fiorent. Coecum of the horse.

404

THE INFUSORIA

Family OPALININA, Stein. Without a mouth. Anoplophrya, Stein.
Oval to elongated in shape, slightly twisted on its axis. A row of contractile
vacuoles along one border. 0'9. Digestive canal of Annelids and Gas-
tropods, and in the blood of some Crustacea. (Fig. 30.) Hoplitophrya,
Stein. Anterior end of the body formed like a sucker and provided with
two hooks. A long tubular contractile vacuole. 0'9. Intestine of
Planarians and Oligochaeta. Discophrya, Stein. A large sucker-like

FlO. 54.

Reproduction of Opalina ranarum. 5, a
specimen in process of binary fission ; 6, the
same ; the process of fission has now reduced
the individuals to a relatively small size ; 7,
smallest fission produced fragment encysted,
expelled from the frog in this state and
swallowed by a tadpole ; 8, young uninucle-
ate individual which has emerged from the
cyst within the tadpole and will now multi-
ply its nuclei and grow to full size. (After
Zeller.)

Fio. 55.

Opalinopsis sepiolae, Foett, a monthless
Holotrichan from the liver of the squid.
a, a, fragments of the meganucleus which
in the younger stages is a continuous rod
or band. 6, ft, non-contractile vacuoles.
X 100.

anterior end without hooks. 2 mm. Digestive canal of Planaria and
Amphibia. Opalina, Purkinje (Figs. 25, 53, 54). The most aberrant of
all the Hymenostomata. No contractive vacuoles. Numerous mega-
nuclei. 0*1. Rectum and occasionally the bladder of several Anura.
Opalinopsis, Foettinger (Fig. 55). Elongated in form, with a swollen
anterior end. In the young forms a band-like meganucleus, which later
breaks up into a large number of irregular fragments. 1-5. Liver and
venous appendages of various Cephalopoda.

THE INFUSORIA 405

ORDER Heterotricha, Stein.

This order includes those Ciliata in which there is a special adoral
zone, armed with specialised long or thick cilia, supported by a delicate
protoplasmic ridge or membranella, and usually spiral in form.

The Order is divided into two Sub-orders : —

Sub-order POLYTHICHA.
Sub-order OLIGOTRICHA.

The sub-order POLYTRICHA includes those HETEROTRICHA in which the
general surface of the body is covered with rows of short cilia. The
longer cilia are usually confined to the adoral zone, but may also occur
in the form of a tuft (Metopus) at the posterior end of the body. The
form of the body may be spherical (Bursaria), oval (Condylostoma), rod-
like (Spirostomum), or trumpet-shaped (Stentor and Folliculina). Most of
the genera are permanently free -swimming, but some are occasionally
(Stentor) or usually (Folliculina) sedentary in habit. In Bursaria, Balan-
tidium, and others the mouth is at the anterior end of the body. In
Chonchophthirus and Spirostomum it is near the middle, whilst in Plagio-
toma it is situated nearer to the posterior than to the anterior end.

This sub-order contains some of the largest Ciliata. The elongated
Spirostomum may be 3 mm. in length, Bursaria is occasionally 1'5 mm. in
diameter, and Stentor and Folliculina 1 mm. in length in the extended
condition. Some genera (Stentor, Folliculina) have considerable powers of
contracting and extending the body. In Spirostomum the contraction is
spiral. Trichocysts have not yet been discovered in any POLYTRICHA.
The meganucleus is oval in Nyctotherus, Blepharisma, Balantidium, and
others. In Spirostomum it is oval at one time and at others it becomes
very elongated and moniliform. In Stentor it is moniliform (Fig. 44).
In Playiotoma and Bursaria it is elongated. In Balantidium and others
only one micronucleus has been seen ; but in Stentor, Bursaria, Spirosto-
mum, etc., there are numerous micronuclei.

The POLYTRICHA contain the following families : —

Family PLAGIOTOMINA, Clap, and L. Conchophthirus, Stein. The
adoral zone represented by a row of long cilia on the anterior border of
the peristome. 0'2. Ectoparasitic on the mucus of several fresh- and
salt-water Pelecypoda. Also found in the body-cavity of various species
of Actiniaria. Plagiotoma, Duj. Slightly contractile. Meganucleus a
long twisted band. 0'4. Parasitic in the intestine of earthworms.
Nyctotherus, Leidy. This is regarded as a sub-genus of Plagiotoma by
Biitschli. It is distinguished from it by its reniform shape and by the
sausage-shaped or oval meganucleus. 0'3. Parasitic in the intestines. of
Anura and various insects and myriopods. (Fig. 56.) Blepharisma, Perty.
Very similar to Plagiotoma, but not parasitic. 0'4. Freshwater. Metopus,
Clap, and L. Oval in form, with a well-developed peristome sinistrally
twisted. There is frequently a large pigmented spot at the anterior end
of the body. 0'3. Marine and freshwater. Spirostomum, Ehrb. The
longest of all the Ciliata. It contracts rapidly in a spiral manner. Very

406

THE INFUSORIA

ll

large elongated contractile vacuole. Numerous micronuclei. 3 mm. in
length when fully extended. Marine and fresh-
water. (Figs. 57, 58.)

Family BURSARINA, Biitschli. Thylaleidium,
Schew. With a long ventral peristome. The
medulla contains numerous zoochlorellae. Fresh-
water in Australia. Balantidium, Clap, and L.
A large peristome and well-marked anal aperture.
0'5. Very common in the rectum of Batrachia,
occasionally found in the large intestine of man
and in the coelom of Annelida. Balantidiopsis,
Biitschli. A smaller peristome than in Balanti-
dium. 0'15. Intestine of Bana esculenta.

Ehrb., as seen from the right Condvlostoma, Dui. Club-shaped in form. The
side, a, meganucleus ; b, a . . ~ , , » , . ,

water vacuole ; c, contractile right border of the peristome bears a large

ionff°ciilad-' /nmicroimaiid °' undulating lip. 0*5. Marine and freshwater.
h, pharynx ; i\ Bursaria, Clap, and L. The peristome is an
is mm. in length, enormous excavation on the anterior and ventral
face of the body. Meganucleus strap - shaped.

Micronuclei 16 or more. 1'5. Very common in some freshwater ponds.
(Figs. 58 and 59.) Bursaridium, Lauterb.

Family STENTORINA, Stein. Climacostomum,, Stein. The form of the

body is oval and shows little con-
tractility. The peristome is large and
oblique. It is in many ways intermediate

Fio. 56.

Nyctotherus cordiformis,

g, mouth ;

FIG. 57.

Spirostmnitm ambiguum, Ehrb. On
the right side of the peristome the long
cilia of the adoral zone, a, a, monili-
form meganucleus ; b points to the
enlarged part of the contractile vacuole;
in front of this letter it is drawn out
into a narrow tube, x 100.

Fio. 58.

Spirally contracted condition of
Spirostomum ambiguum, Ehrb. d.c.v,
the duct of the contractile vacuole ;
a.z, adoral zone ; o, mouth. (From
Biitschli, after Lieberkiihn.) x 120.

between Balantidium and the STENTORINA. 0'3G. Freshwater. Stentor,
Oken. Elongated trumpet -shaped form, with a well -developed adoral
zone at the broadest end. A long moniliform meganucleus and several

THE INFUSORIA

407

nricronuclei.

Some species
$

coloured

m—

blue with Stentorin, others red,
brown, green, or colourless.
They swim rapidly with a
rotatory movement, or attach
themselves by their narrow pos-
terior ends to a foreign object.
Sometimes, in the sedentary
condition, they form gelatinous
tubes. 1 mm. or more in length

FIG. 59.

Bursaria truncatella, O.F.M. The peristome is,
in this form, a deep excavation, the margins of
which embrace a considerable part of the anterior
and ventral surfaces (p). It can be closed by a
sphincter myophan band (s). A thin vertical fold
projects into this cavity on the right side (left in
the figure), and a thicker striated fold projects
into it on the left side. On the dorsal side there
is a gutter (m) leading down to the mouth, and
this is continued into a narrow oesophagus (o).
(After Schuberg.) x ca. 50.

Fio. 60.

Bursaria truncatella, O.F.M. Diagram
of a preserved specimen to show the long
strap-shaped meganucleus (M), and 16
micronuclei (m, m). (Constructed from
the researches of Prowazek.)

FIG. 61.

Stentor polymorphiis,
Miiller. A group of indi-
viduals attached to a water
weed, x 50.

FIG. 62.

An empty Spirorbis shell
bearing a large number of the
tests of Folliculina ampulla.
(After Stein.) x ca. 5 diam.

Fio. 62A.

A specimen of Folliculina as
it is seen when retracted into
its test (<). (After Stein.)

when fully extended. Freshwater. (Fig. 61.) Folliculina, Lamark. The
peristome extended into a pair of large, lateral, wing-like processes. It

403

THE INFUSORIA

is extremely contractile. It forms chitinous tubes attached to Algae and
Shells. 1 mm. when fully extended. Marine and sometimes freshwater.
(Figs. 62, 62A, 63.)

Family GYROCORYNA, Stein. Caenomorpha, Perty. The remarkable
form of this genus is shown in Fig. 64. Its general relations seem to
be with Metopus, one of the Plagiotomina. On the other hand, the absence
of cilia from all but localised parts of the body indicates affinities with the
OLIGOTRICHA. O'l. Freshwater and marine. Closely allied to it is
Caenomorptena, Blochmann.

az

SUB-ORDER OLIGOTRICHA.

In this group the adoral zone
is always situated at the free or
anterior extremity of the body. In
nearly all forms there are areas or
tracts of the surface of the body

az-

Fio. 63.

Follicullna ampulla, C. and L., expanded.
«.«, the bilobed adoral zone ; t, the test ;
c.v, contractile vacuole ; M, meganucleus.
(After Stein.) x ca. 150.

FIG. 64.

Caenomorpha medusula, Perty. From
the ventral side, slightly turned to the
right, a.z, adoral zone ; c.v, contractile
vacuole ; M, meganucleus ; m, micro-
nucleus ; c, cirri. (From Biitschli, after
Blochmann.) x 300.

free from cilia, and in a considerable number of genera there are
localised tufts of cilia (Gycloposthium) or spinous processes of the
body-wall (Ophryoscolex). The body is very variable in shape, and no
particular form of it can be regarded as characteristic of the sub-
order. The sub-order includes a large number of species (TiNTixxoiNA,
etc.) of small size which occur in the plankton of the sea and lakes.
These animals very frequently exhibit curious and very characteristic
darting movements alternating with periods of immobility. Several
genera are internal parasites. The meganucleus is usually a single large
oval body, and is accompanied by one micronucleus.

The OLIGOTRICHA are divided into the following families : —
Family LIEBERKUHNINA (?), Biitschli. Biitschli founded this family
to include certain spherical forms with a spiral adoral zone which were

THE INFUSORIA

409

regarded by Claparede and Lachmann and Lieberkiihn as young stages of
Stentor. Freshwater.

Family HALTERINA, Cl. and L. Strombidium, Cl. and L. More or
less conical in shape, with a spiral adoral zone of long and strong cilia.
There are in addition a few cilia on the ventral surface. 0'04. Marine
and freshwater. (Fig. 65.) Torquatella, Lankester. Closely related to
Strombidium, but with adoral cilia united to form a membranous collar.
A supra-oral papilla. (Figs. 12 and 66.) Found associated with the
eggs of Terebella. Halteria, Duj. Spherical in form, with tactile pro-
cesses scattered on the posterior hemisphere of the body. It remains
motionless for some time and then suddenly darts forward to another
position, where it again assumes its immobility. 0'04. Freshwater.

Family TINTINNOINA, Clap, and L. These are minute forms which
build a gelatinous or chitinous protective shell or case. Tintinnidium,
Saville Kent. The case is gelatinous and tubular, sometimes free, some-
times attached to foreign objects. Freshwater. Tintinnus, Fol. With a

Fio. 05.

Strombidium claparedii,
Kent, a, meganucleus ;
b, contractile vacuole.
x 200.

Fio. 66.

Torqitatella typica,
Lankester. Side view
to show the supra-
oral papilla (/>) as
seen through the
membranous collar.
Cf. Fig. 12.

Fio. 67.

Codonella lage-
nula, Cl. and L.
X 200.

Fio. 68.

Empty shell of
Codonella campa-
nella, Haeckel.
x 180.

chitinous shell shaped like a test-tube with a slightly constricted neck.
0*3. Marine. Tintinnopsis, Stein. Shell conical in shape, very thin, and
sometimes strengthened by agglutinated foreign particles. 0'2. Pelagic
plankton. Codonella, Haeckel. Pot-shaped shell, ornamented with hexa-
gonal ridges. (Figs. 67 and 68.) In some species there is an apparatus
for closing the orifice of the shell. O'l. Marine and freshwater.
Ptychocylis, Brandt. Marine. Porella, Cleve. Marine. Didyocysta, Ehrb.
O'l. Marine.

Family OPHRYOSCOLECINA, Stein. The following genera composing
this family occur in the rumen of the cow and some other Artiodactyla.
Ophryoscolex, Stein. At the anterior extremity there is a funnel-shaped
peristome provided with many large cilia. Running spirally round the
anterior end of the body there is an adoral membranella provided with a
few thick cilia. There is a well-marked anus. At the posterior end of
the body there is a spinous prolongation of the cortex, and similar spinous
processes occur in circular elevations for some considerable distance in
front of it. There are several contractile vacuoles. 0'1-0'3. Entodinium,
Stein. Oval in form, with a spinous caudal process. No spiral mem-

4io

THE INFUSORIA

branella round the body. 0-03-0-12. Diplodmium, Schuberg, differs

FIG. 69.

Cycloposthium bipalmatum, from
the coecum of the horse. M,
meganucleus ; m, micronucleus ;
L, peculiar vacuolated band by
the side of which is situated a
row of contractile vacuoles.
(After Giinther.)

Pio. 71.

Stichospira paradoxa, Sterki.
Length about -04 mm. Living in
a cavity of a leaf which is extended
forward by the addition of a tube (<)
built by the animal itself, c, mouth ;
M, meganuclei ; e.v, contractile
vacuole. (After Sterki.)

versely across the posterior
between these two groups a

FI0. 70.

Diagrammatic transverse section through the body
of a Hypotrichous Ciliate in the region of the peri-
stoine. a, membrane overhanging the mouth ; 6, a
ventral cirrus ; c, a lateral cirrus. On the dorsal
side are rows of stift', bristle-like cilia. (After Sterki.)

from Entodinium in the presence of a
portion of the adoral membranella on the
left side of the body. The genera Cyclo-
posthium, Bundle (Fig. 69), and Didesmis,
Fior., from the coecum of the horse, should
be separated into a distinct family.

APPENDIX. — The genus Maryna, Gruber,
is probably related to the TINTINNOINA, and
should be included in the OLIGOTRICHA.
The individuals live in colonies which form
a system of dichotomously branched mucous
tubes. Freshwater.

ORDER Hypotricha, Stein.

The genera included in this order are
usually characterised by a well-marked com-
pression of the body in the dorso- ventral
axis. The dorsal surface has no movable
cilia, but is usually provided with a few
scattered, stiff, bristle-like processes of the
pellicle (Fig. 70). The ventral surface is
provided with a continuous covering of
short cilia, arranged in longitudinal rows,
in the more primitive forms (Urostyla,
Peritromus), or with more differentiated
rows or groups of cirri and membranellae
associated or not with small cilia. The
most important of the cirri are usually
arranged in three groups (cf. Fig. 1), one
just behind the anterior margin called the
frontal cirri, a row usually running trans-
ventral surface called the caudal cirri, and
number of abdominal cirri (3-10) arranged

THE INFUSORIA 4 1 1

in irregular rows or unevenly scattered. The HYPOTRICHA are usually
found creeping on the surface of animals, plants, the scum of putrefac-
tions, or the surface film of water. The progression is effected entirely
by the cilia or cirri on the ventral surface of the body, which are used
like the legs of higher animals. The most modified form is Stichospira
(Fig. 71), which is elongated in shape and uses its ventral cirri to
crawl up and down a short mucilaginous tube which it constructs on
the epidermis of plants.

The HYPOTRICHA are nearly all small ('3 to '4 mm.) or very small
('03-'01 mm.) in size, and they are usually very active in their move-
ments. The meganucleus sometimes exhibits a remarkable fragmentation
during the intervals between the acts of fission as described on p. 372
(Figs. 16 and 17). A majority of the genera have been described by
authors as possessing either two nuclei or a single two-jointed nucleus.
It is probable that this double- or twin-nucleus condition is one phase,
characterised by its considerable duration, in the process of nuclear
fragmentation. Stylonychia and Euplotes each possess one minute micro-
nucleus, but in most of the genera very little is known about the
micronuclei.

The order HYPOTRICHA is divided into the following families : —

Family PERITROJIINA, Stein. Peritromus, Stein. This is the simplest
form of the HYPOTRICHA, the ventral ciliation being uniform and dense
and without any differentiation of stouter cilia or cirri. O'l. Marine.

Family OXYTRICHINA, Stein. Trichogaster, Sterki. 0'23. Fresh-
water. Urostyla, Ehrb. Elongated in form. Ventral cirri arranged in five
or more longitudinal rows. Enlarged cirri in the frontal region and in a
transverse row near the posterior extremity. 0'3. Marine and fresh-
water. Kerona, Ehrb. Kidney-shaped. Six or seven oblique rows of
small cirri on the ventral side. O'l 5. Found creeping on the ectoderm
of Hydra. Epiclintes, Stein. The number of rows of ventral cirri is
reduced to five or six, but there are no special frontal or caudal cirri.
0'3. Marine. Stichotricha, Perty. The anterior extremity is prolonged
into an extremely flexible proboscis, on which the adoral zone is extended.
Either free or attached by gelatinous tubes, which sometimes form den-
dritic colonies. O'l. Marine and freshwater. Stichospira, Sterki. On
freshwater plants (Fig. 71). Strongylidium, Sterki. Freshwater. Holo-
sticha, Entz. Two rows of marginal cirri, between which are two or three
rows of cirri without special differentiation of frontal cirri. A tranverse
row of caudal cirri. 0'4. Marine. Amphisia, Sterki. With differen-
tiated frontal cirri. Marine and freshwater. Uroleptus, Ehrb. Three
well -developed frontal cirri. Sometimes rose or violet in colour. 0'5.
Marine and freshwater. Sparotricha, Entz. Similar to Spirotricha, but
the adoral zone does not extend beyond the middle of the proboscis. O'l.
Salt marshes in Hungary.

Family PLEUROTRICHINA, Biitschli. In this family the frontal cirri
are well developed and usually eight in number. There are also specialised
abdominal and caudal cirri. Onychodromus, Stein. Three or four ab-
dominal cirri. 0'35. Freshwater. Pleurotricha, Stein. Five strongly-
developed abdominal cirri and a row of five transverse caudal cirri. 0'4.

412

THE INFUSORIA

Freshwater. GastrostylajlEngelmann. A row of several well-developed ventral
cirri. 0'32. Freshwater. Gonostomum, Sterki. Very small peristome.
0'20. Marine and freshwater. Urosoma, Kowalewsky. Posterior end drawn
out into a long caudal process. Eight abdominal cirri. 0'24. Freshwater.
Oxytricha, Ehrb. Five abdominal and five caudal cirri. Caudal spines usually
present, but not well developed. 0-2. Freshwater and marine. Stylo-
nychia, Ehrb. The right margin of the peristorne is bent in an S-shaped
curve. Three very long caudal spines (Figs. 72 and 73). 0'4. Fresh
water and marine. Histrio, Sterki. Closely related to Stylonychia. Fresh-
water. Actinotricha, Cohn. Peristome reduced in size. The left border

Stylonychia pustulata pre-
vious to encystment. The
granules of waste matter (Ex)
collected in clusters, some
of them already, discharged ;
M,M, meganuclei ; c.v, con-
tractile vacuole. (After Pro-
wazek.)

Fio. 73.

Cyst of Stylonychia pustu-
lata. (After Prowazek.)

FIG. 74.

1, Didinium nasvtum, Miiller, one of the
GYMSTOSTOMATA, see p. 399. x 200. The pharynx
is everted and has seized a Paramoedum as prey.
2, Euplotes clMron, Miiller. Side view. A tuft of
frontal cirri may be seen in front (right of dia-
gram) ; a few abdominal (x) in the middle of the
ventral side ; and a group of five (x) forming
the transverse row of caudal cirri. 3, Euplotes
harpa, Stein, x 150. Ventral view, h, mouth ;
x, hypotrichous processes.

bears a number of large menibranellae arranged in the form of a fan.
O'l. Marine.

Family PSILOTRICHINA, Biitschli. Small forms in which the frontal
and abdominal cirri are not clearly differentiated. Balladina, Kow. All
the cirri are remarkably elongated. 0'04. Freshwater. Psilotricha,
Stein. Anterior end broad, posterior end more constricted. Very broad
peristome. O'l. Freshwater. Dipleurostyla, Roux. Freshwater.

Family EUPLOTINAE, Stein. The principal character is the great
reduction in the ciliation of the body. Euplotes, Stein. (Fig. 74, 2.) Peri-
etome extensive. Six or seven frontal cirri and a transverse band of five
cirri in the caudal region. 0'2. Freshwater and Marine. Diophrys, Duj.
The peristome even more extensive than in Euplotes, reaching as far back
as the row of caudal cirri. O'l 5. Marine. Uronychia, Stein. The frontal
cirri missing. O'l. Marine.

THE INFUSORIA 413

Family ASPIDISCINA, Stein. Aspidisca, Ehrb. The peristome is
entirely on the left side. Marginal cirri completely reduced. Mega-
nucleus band-shaped. 0'07. Marine and freshwater.

ORDER Peritricha, Stein.

In this order the cilia are generally confined to a single spiral girdle
situated at the margin of the adoral disc, and the vestibule. In Trichodina,
Cyclochaeta, and Licnophora there is a second girdle of cilia at the aboral
end. In some cases the adoral girdle of cilia is surrounded by a ridge or
collar of the pellicle which is not ciliated, and in some species of Varticella,
etc., this can be constricted above the adoral disc during retraction in a
similar manner to the constriction of the margin of the disc of a sea-
anemone. In Spirochona there is a delicate spiral membrane at the adoral
end of the body (Figs. 22 and 23), but it is difficult to determine whether
this membrane should be regarded as due to a fusion of the cilia of a
spiral girdle or to an exaggeration of a spiral collar. The general surface
of the body of the Peritricha is naked. Nearly all the Peritricha are
sedentary in habit during the greater part of their existence. The
LICNOPHORINA readily leave their host and swim away. Many of the
VORTICELLINA break away from their peduncles and form a new one
when another suitable situation for attachment is found. The tubicolous
forms leave their shelter if the food supply fails and seek another locality.
It is probable, indeed, that none of the PERITRICHA are absolutely sedentary.

In the more primitive forms the attachment is made by the aboral
disc, which acts like a sucker and can readily be released. The disc may
be provided not only with a peripheral girdle of cilia, but also with an
armament of hooks (Trichodina) or cirri (Cyclochaeta).

In SpirocJiona and Kentrochona (Figs. 3 and 22) the adhesive disc is a
simple expansion of the body-wall, sometimes exhibiting pseudopodial lobes.

The arrangement of the spiral girdle or collar may be either left-
handed (scaiotrichous) as in the LICNOPHORINA and SPIROCHONINA, or
right-handed (dexiotrichous) as in the other Peritricha with a spiral girdle.

In Epistylis and Opercularia the body is provided with a long rigid
stalk or peduncle, and in Carchesium and Vorticella with a peduncle that
is capable of very rapid spiral contraction. The genera Cothurnia (Fig.
81), Vayinicola, etc., secrete a shell or tube which is attached to some
animal or plant, and in Ophrydium a colony of stalked individuals (Fig. 2)
secretes a common mucilaginous investment.

The Peritricha may be either solitary in habit (Vorticella, Spirochona,
Cothurnia) or associated together in colonies (Epistylis, Fig. 78, Carchesium,
Ophrydium, Fig. 2).

The mouth is usually situated at the bottom of a deep, ciliated, funnel-
shaped vestibule (see Fig. 27), and may open into a globular pharyngeal
vacuole. The anus (cytopyge) usually opens near the mouth of the
vestibule (Fig. 27), but is, with rare exceptions, only temporarily open.
In Epistylis umbellaria large nematocysts occur (Fig. 75), but these organs
are absent in other Peritricha.

The meganucleus of the Peritricha is usually a long, bent, horse-

414 THE INFUSORIA

shoe-shaped, or strap-shaped body. The micronucleus is, in the resting
condition, extremely minute and difficult to observe.
Only one micronucleus is usually present in each indi-
vidual.

The order PERITRICHA is divided into the following
families : —

Family SPIROCHONINA, Stein. Spirochona, Stein.
_ (Fig. 22.) Attached to the gills of Gammarusby a sucker.

PIG 75 Mouth surrounded by a delicate spiral membrane, the

Nematocysts of inner surface of which is partially provided with ex-
Epistyiis umbel- tremely minute cilia. Reproduction DV external eem-

laria. a, with the . ' , . ",

thread at rest ; b, mation. Meganucleus oval or spherical, with a clear
discharged '(After zone containing in the resting state a single chromatin
Greef.) Each cap- body — the nucleolus (?). One to three micronuclei. 0'12.
fn1ieDgthb°Ut Klt Gills of Gammarus. Kentrochona, Rompel (Fig. 3). Adoral
membrane in the form of a large wide-mouthed funnel,
not spirally twisted. This is supported by four columnar thickenings
which project as spines from the margin of the funnel. Meganucleus
spherical. 3-4 micronuclei. O04. On the limbs of Nebalia. Kentro-
chonopsis, Doflein. With multiple endogenous gemination. Six micro-
nuclei. Gills of Nebalia geoffroyi. Chilodocona, Wallengren. Maxillae
and maxillipedes of Ebalia and Portunus.

Family LICNOPHORINA, Biitschli. Spiral girdle scaiotrichous and
ciliated. Licnophora, Clap. Aboral sucker surrounded by a circle of cilia.
O'l 2. Attached to several marine Invertebrata such as Medusae, Pelecy-
poda, Polychaeta, etc.

Family VORTICELLINA, Biitschli. Trichodina, Stein. Cylindrical in
form, with an adhesive disc surrounded by a ring of cilia. O'l. Found
on the surface of Hydra, Sponges, Planarians, and other freshwater
animals ; and also occasionally in the bladder of Frogs, Newts, and
Fishes. Cydochaeta, Jackson. With a ring of very long bristle -like
processes just above the ring of cilia of the adhesive disc. O'l. On
Spongilla, on the gills of Scorpaena, Trigla, and Serpula, and on the
surface of Asteriscus and Ophiothrix. Trichodinopsis, Clap, and L. A
remarkable form, with a very much constricted oral extremity, causing
the body to assume a conical shape. The whole surface of the body
between the oral and aboral rings of cilia covered with long cilia. O'l 3.
Parasitic in the gut and lung of Cyclostoma. Scypliidia, Lachmann.
Cylindrical forms without a stalk and without an aboral ring of cilia.
O'l 2. Attached by the aboral sucker to the skin of freshwater and
marine Mollnsca. Gerda, Clap, and L. Cylindrical in form, with the
oral region considerably constricted. Very contractile. When swimming,
a ring of cilia is formed at the aboral end. 0'2. Freshwater. Hastatella,
Erlanger. With long spinous processes. Stagnant freshwater. Astylozoon,
Engelmann. Free, with a pointed posterior extremity provided with
two or three saltatory bristles. O'l. Freshwater. Vorticelta, Linnaeus,
1767, emend. Ehrb., 1838. (Figs. 76 and 77.) This genus is now con-
fined to those Vorticellids with a simple unbranched contractile stalk.
A large number of species have been described, but as there is great

THE INFUSORIA

415

Fio. 76.

Vorticella mifrostoma, Ehrb.
On the left a female with two
males (c.d) attached to it.
Only one (d) is in the act of
conjugation. a, meganu-
cleus; b, contractile vacuole ;
e, ciliated disc ; /, vestibule.
On the right an individual
with the stalk contracted
and the body enclosed in a
cyst.

Cyclops with several col-
onies of Epistylis anastatica
attached to the antennae and
somites. (After Saville Kent.)
x 10.

Fio.

Opercidaria stenostama, Stein.
Observe the undulating mem-
brane of the oral vestibule and the
oblique ciliate disc, x 200.

FIG. 77.

Vorticella nebulifera, Ehrb. A social group showing at
a and b successive stages of fission, and at c, conjugation.
(After Saville Kent.)

FIG. 79.

Epistylis anastatica, Linn. Colonial stocks attached
to the limbs of Cyclops. (After Saville Kent.) x 100.

416

THE INFUSORIA

difficulty in distinguishing between true specific characters and local
variations, a great many of the described species are not generally
recognised as distinct. 0'2 in height. Cosmopolitan in freshwater, also
marine. Carchesium, Ehrb. "With contractile, branched, and colonial
stalks. The colonies sometimes 4 mm. in height. Attached to freshwater
plants and animals in Europe and N. America. Zoothamnium, Ehrb.
In Carchesium every new individual that is formed secretes its own
peduncle, and retains its power of independent contraction. In Zootham-
nium, on the contrary, the peduncle of the parent splits during fission
as far down as the next branch, and the colony retracts as a whole.
Individuals 0'08. Colonies sometimes several mm. in length. Marine
and freshwater. Glossatella, Biitschli. Stalk very rudimentary. An
enormous undulating membrane round the
peristomial margin. 0'04. Attached to
Triton larvae. Epistylis, Ehrb. Forming

FIG. 81.

FIG. 82.

81. — Cothurnia (Pyxi-
cola, Kent) affinis, Kent.
Expanded, x, operculum.

82. — Cothurnia (Pyxi-
cola, Kent) affinis, Kent.
Retracted, x, operculum
closed.

Fio. 83.

Co</M<rnia(Thuricola) val-
vata, Wright. On the left
two expanded individuals
are, as a result of fission,
temporarily occupying one
tube, u, valve. On the
right, the same retracted,
the valve it closed like the
door of a trap-door spider's
nest.

colonies similar to those of Carchesium, but with non-contractile peduncles.
(Figs. 78 and 79.) Colonies 4 mm. in height. Individuals O8. Princi-
pally found attached to freshwater animals. (Figs. 78 and 79.) Ehabdo-
styZa, Kent. Similar to Epistylis, but solitary. -09. On larvae of Diptera.
Opercularia, Stein. (Fig. 80.) The disc is oblique, and the peristome is
provided with an undulating membrane. Peduncle as in Epistylis, branched
and rigid. 0'25. Freshwater. Campanella, Goldfuss. The adoral zone
of cilia greatly developed, forming five complete turns. 0'15.
Colony 4 mm. Freshwater. Ophrydium, Ehrb. (Fig. 2.) Colony
secreting a common mucilaginous test. 0'4. Freshwater. Cothurnia,
Clap, and L. Individuals secrete a cylindrical test, provided with a
lid which can shut down over the contracted individual. (Figs. 81, 82, 83.)
0*4. Marine and freshwater. Cothurniopsis, Entz. Individuals usually
more isolated than in Cothurnia. Commonly found on the gills of Astacus

THE INFUSORIA

417

and other freshwater Crustacea. Probably also marine. Vaginicola,
Clap, and L. Test of the shape of a recumbent soda-water bottle. O'l.
Attached to freshwater plants. Lagenophrys, Stein. Forming a spherical
mucilaginous test. 0'07. Attached to the gills of Gammarus and Asellus.
Nematopoda, Sand.

APPENDIX TO THE CILIATA.

Family TRICHONYMPHIDAE, Leidy. It is a matter of considerable
difficulty, with our present knowledge, to determine the exact relations
of this family. The long cilia, some mobile and some immobile, the
general shape of the body, and the endo-parasitic habit, suggest relations
with some of the endo-parasitic Holo-
tricha. On the other hand, the absence
of a definite mouth, associated with the
habit of engulphing solid food at indefinite
parts of the general surface of the body,
is a condition which definitely separates
them from any of the orders of the Ciliata.
Micronuclei have not yet been described,
and it is therefore possible that they are
homokaryote.

The TRICHONYMPHIDAE occur in im-
mense numbers in the intestines of certain
Orthoptera, more particularly in Termes
flavipes. In Trichonympha (Fig. 11) the
body is differentiated into three regions —
an anterior translucent knob, a middle or
bell-shaped part, and a posterior part or
body. The anterior knob is extremely
active in the living animal, and constantly
in motion. The shorter cilia of the
middle region are active, and produce the
movements of the body. The longer cilia
of the posterior part are absolutely motion-
less, and are said to entangle particles
which become subsequently engulphed by
the protoplasm of this region (Porter).
In Pyrsonyrnpha the anterior knob is
prolonged into a very delicate filament,

FIG. 84.

Pyrsonyrnpha vertens, Leidy, attached
by a delicate filament to the epithelium

which perforates the epithelium of the a specialised (muscular?) band running
..',.* P ., i j through the whole length of the med-

intestme of the host and serves as a una. (After Porter.) x 400.

means of attachment. The ciliation of

the body is, in this fixed form, very much reduced.

The genera of TRICHONYMPHIDAE are : Lophomonas, Stein. The
flagellate cilia are confined to a horse-shoe-shaped crescent at the anterior
end of the body. 0'03. Rectum of Periplaneta, Gryllotalpa. Leidyo-
nella, Frenzel. Anterior extremity prolonged to form a short neck, in
other respects similar to Lophomonas. 0'45. Eectum of Eutermes.
Trichonympha, Leidy. Body divided into three regions, all provided with

27

4i 8 THE INFUSORIA

long flagellate cilia. O'l 2. Rectum of Termes. Joenia, Grassi. Similar
to Lophomonas, but more elongated, and with a number of short non-
mobile cilia at the posterior end. Rectum of Callotermes. Pyrsonympha,
Leidy. (Fig. 84.) With a long anterior flagellum of attachment. O'l.
Rectum of Termes. Dinennymplw,, Leidy. More elongated than Pyrso-
nympha, and spirally twisted. O'l. Rectum of Termes.

CLASS ACINETARIA, LANKESTER

The majority of the animals included in this class are per-
manently or temporarily sedentary in habit. It seems probable,
however, that some of the species of the genus Sphaerophrya may
be permanently free.

The characteristic feature of the class is the possession of the
organs known as Suckers, Tentacles, and Arms. The morphology
of these organs is discussed in another place (p. 370).

In Rhynceta (Fig. 1 3) there is only one sucker, and in Hypocoma,
which may be only a persistent larval form, the single ventral
sucker is supplemented by a patch of cilia on the same aspect of
the body. In Sphaerophrya the body is furnished with a few
suckers evenly distributed, and in the pedunculate Acineta there are
numerous suckers scattered on the surface that is free. In some
species of Ephelota the suckers and tentacles are evenly distributed
on the free surface, whilst in ToJcophrya, Podophrya, and Solenophrya
the suckers are restricted to three or four bunches at the angles of
the disc. In Dendrocometes these bunches of suckers are represented
by 4-6 arm-like processes of the body-wall, and very probably the
1-4 arms of the remarkable genus Ophryodendron have a similar
significance.

The attachment of the individual to the host or to some foreign
weed or other substance may be effected by a broad flattened base
as in Dendrocometes, Dendrosoma, Solenophrya, or by a stiff cuticular
peduncle with a protoplasmic core as in Acineta and Podophrya.

There is, as a general rule, no mouth, the food being held by
one or more of the suckers and the dissolved products passing
down the suckers into the general protoplasm of the body.

The body-wall is covered with a thin pellicle which is in many
forms finely loricate. Some species have the power of withdrawing
themselves from this pellicle, which is left behind as a shell, together
with a certain amount of cytoplasm. They then develop a temporary
covering of cilia and swim away to a more suitable locality. The
cilia disappear when the individual again becomes fixed. This has
been observed in Dendrocometes, but it probably occurs in other
genera as well (Podophrya and Metacineta).

The peduncle of the Acinetaria appears to be formed as a

THE INFUSORIA 419

secretion by the pellicle of the inferior surface of the body, and it
is never contractile. In many forms it expands distally to form a
saucer-shaped expansion (Podophrya, Ephelota] for the support of the
body or (Metacineta) a protective cup for its reception during
retraction.

A large number of the Acinetaria are epizoic in habit, and very
frequently a particular species is only found on one genus of host.
For example, Rhynceta occurs only on the abdominal appendages of
Cyclops, and Dendrocometes on the gills of Gammarus. The species
of Eplielota are frequently associated with particular species of
Hydroids ; Stylocometes is usually found on the gills of Asellus, but
has also been found on the colonies of Ophrydium. The species
of Acineta are usually found attached to water weeds. Some species
of Spliaerophrya after a brief free-swimming life in the water attack
various Ciliata and become parasitic. Endosphaera is parasitic on
Vorticellina and some Acinetaria. The phenomenon of conjugation
has been observed in Dendrocometes, Podophrya, Tokophrya, and
probably occurs throughout the group. In Podophrya the discs of
two neighbouring individuals are brought together and fusion of
the protoplasm of the two is thus effected. In Dendrocometes and
Stylocometes, however, a special pseudopodium from the body-wall
of each of two neighbouring individuals is produced, and these
meet and fusion takes place. It would be interesting to know
what stimulus causes these processes to form at the same time and
grow together. The reproduction is usually brought about by
gemmation. In the parasitic species of Spliaerophrya a division
into two equal halves takes place soon after the parasites have
reached their full size. This is followed by a rapid series of equal
divisions, and finally the spores that are thus formed develop suckers
and escape as small free-floating individuals. At this stage a
division occurs into two almost equal segments, but the smaller of the
two is provided with suckers and cilia, and may be regarded as a
bud, while the larger, which has suckers but no cilia, may be regarded
as a parent. There is, however, no sharp line to be drawn between
the processes of fission and gemmation in these animals : they are
probably of essentially the same nature. But the case of Spliaero-
phrya is interesting as it exhibits two phases of the reproductive
processes (fission in the parasitic form, gemmation in the free) which
are very closely related, but sufficiently distinct to justify a different
nomenclature.

In the stalked forms Podophrya and Metacineta, the disc divides
horizontally into two almost equal parts, but the distal part is
ciliated and has no suckers, whilst the proximal part attached to
the stalk has suckers and no cilia. In Dendrocometes there is a
division into two approximately equal parts, but in this case the
smaller ciliated part or bud is separated from the other internally

420 THE INFUSORIA

and remains for a little while free inside a chamber (brood chamber)
of the other part or parent, which is provided with arms and is not
ciliated. The application of the terms " gemmula " and " parent "
to the two parts in this case is clearly appropriate.

In many species of Ephelota a number (6-16) of gemmulae are
formed at the free surface of the disc, and these may be ciliated
(Fig. 1 4), or provided with tentacles and a small special disc of cilia
(Fig. 96), when they are set free. Finally, in some species of Acineta
and in Ophryodendron, several ciliated buds are formed in a chamber
similar to the chamber containing the single bud in Dendrocometes.

The free-swimming buds of the Acinetaria are frequently called
the " embryos," but as this term may lead to a misunderstanding as
to their origin, it is better to call them simply buds or " gemmulae."
The gemmulae are sometimes oval in shape, as in certain species
of Sphaerophrya, Podophrya (Fig. 20), Ephelota, etc. ; spherical, as in
certain species of Trichophrya ; or plano-convex, as in Dendrocometes.
As regards the ciliation, they may be holotrichous, as in Tokophrya
elongata ; or hypotrichous, as in Hypocoma, Ephelota gemmipara,
etc. The form of ciliation which is most commonly met with is that
of a broad band or girdle encircling the equator of the gemmula,
or two or more narrow bands arranged in a peritrichous manner as
in Dendrocometes and Dendrosoma (Figs. 86 and 33).

The method of feeding of the Acinetaria is remarkable. The
suckers have the power of seizing and holding fast Ciliate and other
Protozoa of considerable size. This power might be explained on
the supposition that they can exert a sucking action, but there can
be no doubt that the prey is not only held fast but also stunned
or paralysed in some way by the Acinetarian. Very soon after
the prey is secured very small globules may be seen passing rapidly
down the sucker (or arm) into the cytoplasm of the disc, proving
that the paralysis of the prey is quickly followed by the digestion
of its protoplasm and its absorption in a liquid form.

Very little is known about the encystment of the Acinetaria.
Some species of Podophrya and Ephelota form cysts which are
probably more resistant to unfavourable physical conditions than
the active phase of life. Dendrocometes, however, and probably
other genera, may be found at all times of the year, and never
show any signs of encystment.

There is considerable difficulty in dividing the Acinetaria into
families, as the whole life-history of very few species has yet been
worked out. Sand has shown that Podophrya gelatinosa, Buck, passes
from the ciliated gemmula into a stage similar to Sphaerophrya,
and that from the Sphaerophrya stage it changes into a form like
Trichophrya before it assumes the adult Podophrya form. In this
stage it may separate from the peduncle, become ciliated again, and
then change into a Sphaerophrya and reproduce by fission or develop

THE INFUSORIA

421

a new stalk and return to the Podophrya condition. If other species
have a similar life -history, as is very probable, our classification
must be regarded as quite provisional.

The Acinetaria contain the following families according to the
classification of Sand : —

Family DENDROCOMETINA, Stein. Epizoic Acinetaria of medium
size without a peduncle. Hemispherical or lenticular in shape. Numerous
tentacles arranged in several bundles, the individual tentacles being fused
together for the greater part of their course to form the "arms," but
independent at their free extremities. Each contains a single contractile
vacuole. Reproduction by the formation of a single endogenous gemmula.
Dendrocometes, Stein, is found on the
gills of Gammarus pulex. In Europe
the gills of this species appear to be
very rarely free from this epizoon, and
sometimes bear them in great numbers "iC." 1^5 A

Fio. 85.

Dendrocometes paradoms, Stein.
Epizoic on the gill of Gammarus. a,
meganucleus ; b, contractile vacuole;
c, a small organism paralysed and
held fast by one of the arms, x 350.

Free-swimming gemmulae of Den-
drocometes paradoxus, Stein, as seen,
A, from the side, B, from below. M,
meganucleus ; in, micronuclei ; c.v,
contractile vacuole. (After Biitschli.
The micronuclei have been added by
the author from original prepara-
tions.) x ca. 300.

(Fig. 85). Stylocometes, Stein, is found on the gills of Asellus aquaticua
and, rarely, on the gills of Gammarus and on colonies of Ophrydium. It
differs from Dendrocometes in having more numerous arms (10-12).

Family DENDKOSOMINA, Biitschli. Characterised by the lobed or rami-
fied form of the body, each lobe or branch bearing a number of suckers.
There is no peduncle. Trichophrya, Clap, and L. The body is lobed, ovoid,
or hemispherical in shape. It is sometimes attached at one point or disc,
but sometimes free and amoeboid. When the body ia distinctly lobed
the suckers are confined to the free ends of the lobes ; in other forms the
tentacles are more irregularly scattered. There are nine species, and they
are found on the gills of fish (perch and pike), on the abdominal segments
of Cyclops, on Epistylis, Conferva, Anacharis, on Salpa, on Algae, Hydroids,
etc. Dendrosoma, Biitschli. This form (Figs. 32 and 87) reaches to a
considerable size, 2 '4. In its fully developed condition it consists of a
number of long lobes of branches rising from a creeping stolon. There is
a continuous axial meganucleus extending throughout the branches of the
stolon and the upright lobes. At the extremity of each lobe there is a

422

THE INFUSORIA

cluster of delicate suckers. Keproduction is by means of endogenous
gemmulae and by external non-ciliated fragments which break off from
the lobes and give rise to new individuals. They are found on Anacharis
and Myriophyllum.

Family OPHRYODENDRINA, Stein. Ophryodendron, Clap, and L.
The body is usually oval or columnar in shape. It is fixed at the
posterior extremity. With or without a peduncle. At the anterior
extremity there are one to four processes of the body provided with
numerous styliform tentacles. The animal produces by internal
gemmation numerous gemmules with peritrichous cilia. O84. Marine.
Attached to Hydroids, Algae, and the limbs of Crustacea (Fig. 87).

FIG. 87.

1, Dendrosoma radians, Ehrb.
An early stage in development,
with only a single branch
springing from the attached
gemmula. x 600. For adult
colony see Fig. 32, p. 384. 2,
Ophryodendron pedicellatum,
Hincks. x 300.

FIG. 88.

A specimen of Stylony-
chia mytilus, containing a
cyst of endoparasitic
spores (It) of SphaeropJirya
pusilla, Clap, and L. o, a,
the two meganuclei.

Family HYPOCOMINA, Butschli. Plano-convex in shape, with a single
sucker on the ventral side. Numerous cilia on the ventral side. Hypo-
coma, Gruber. 0'046. On the peduncles of various marine Vorticellids.

Family URNULINA, Fraipont. Rhynceta, Zenker. (Fig. 13.) Cylindrical
in form, with one long sucker. No cilia. 0'09. Freshwater. Attached
to the limbs of Cyclops, and the gills of Gammarus. Urnula, Clap,
and L. Urceolate test. Body oval or spherical. One or two filiform
tentacles. Gemmula holotrichous. '12. On the peduncle of Epistylis
plicatilis. Acinetopsis, Robin. Cupuliform test attached by a short
peduncle. A single flexible tentacle. -08. On Sertularia.

Family PODOPHRYINA. Podophrya, Butschli. Pedunculate. Body
spherical, with numerous tentacles scattered over its distal surface. A
single gemmula formed at a time. -08. Freshwater. Sphaerophrya, Clap,
and L. (Figs. 88 and 89.) Non- pedunculate. Spherical in form.
Numerous scattered suckers. Sometimes endoparasitic on Paramoecium,
Stylonychia, etc. -08. Freshwater. Endosphaera, Engelmann. Life-
history little known, but in adult stage probably wholly endoparasitic on

THE INFUSORIA

423

Vorticellids and Acinetaria. Amoebophrya, Koppen. (Fig. 90.) With
a circlet of tentacles and a spiral groove provided with cilia in the free

FIG.

1, Sphaerophrya magna, Maupas. x 300. It has seized with its suckers, and is in the*,act
of sucking out the juices of six examples of Colpoda parvifrons. a, meganucleus ; b, contractile
vacuoles. 2, Sphaerophrya urostylae, Maupas. x 200. Normal adult, a, meganucleus ; b, con-
tractile vacuoles. 3, the same dividing by transverse fission, the anterior moiety with temporarily
developed cilia. 4, 5, 6, Sphaerophrya stetitorea, Maupas. x 200. Parasitic in Stentor, and at
one time mistaken for its young. 7, Trichophrya epistylides, Cl. and L. o, meganucleus ; t>,
contractile vacuoles.

FIG. 90.

Amoebophrya •sticholonchae (at A) encysted in the protoplasm of the Acanthometrid
Sticholonche zanclea. C, central capsule of the Sticholonche. (After Borgert.) x 260.

state. Without cilia or tentacles in the parasitic stage. Endoparasitic in
Acanthometra and Sticholonche.

424

THE INFUSORIA

FIG. 92.

Gemmula of Tokophrya cyclopum,
Cl. and L., x750, with an equatorial
band of cilia. M, meganucleus ; c.v,
contractile vacuole. (After Schewia-
koff.)

FIG. 91.

ToTcophrya cyclopum, Cl. and L. M, meganucleus ;
p, pedicle ; c.v, contractile vacuole ; G, gemmula in
brood chamber ; S, groups of suckers. (After Schewia-
koflf.) X 1000.

FIG. 93.

Tokophrya elongata, Clap, and L.
a, meganucleus ; 6, 6, contractile
vacuoles. x 150.

FIG. 94.

Acineta grandis, Kent,
X 100, showing peduncu-
lated lorica and disc with
two bunches of suckers.
a, meganucleus.

Fio. 95.

A single head of a species of
Ephelota, with three whorls of ten-
tacles. (After Ishikawa.) The indi-
vidual is '5 mm. x '16 mm. in size.

Family METACINETINA, Biitschli. Metacineta, Butschli. Body
capable of being completely retracted into the conically expanded
termination of the peduncle. 0'7. Freshwater.

LITERATURE OF THE INFUSORIA

425

Family ACIXETINA, Biitschli. Hallezia, Sand. Animal attached by
a small protoplasmic knob. Numerous suckers at the anterior extremity.
Several endogenous gemmules formed at one time. '18. Freshwater.
Tokophrya, Biitschli. (Figs. 91, 92, 93.) Pedunculate, but with the
saucer-shaped terminal expansion absent or slightly developed. Suckers
fasciculate or dispersed. Endogenous gemmation. -25. Freshwater and
marine. Acineta, Ehrb. (Fig. 94.) Pedunculate, with well-marked

FIG. 96.

A single gemmula of a species
of Ephelota, showing on the right
a small disc of cilia mounted on
the end of a long stalk. (After
Ishikawa.)

FIG. 97.

Ephelota (Hemiophrya)
gemmipara, Hertwig. Ex-
ample with six gemtnulae
in process of formation,
into each of which a
branch of the meganu-
cleus (a, a) is extended.
(After Hertwig.) x 400.

terminal expansion of the peduncle. -3. Marine and freshwater. Soleno-
phrya, Clap, and L. With terminal expansion of the peduncle globular in
form.

Family EPHELOTINA, Sand. Ephelota, Wright. Tentacles and
suckers on the anterior surface. Reproduction by multiple exogenous
gemmulae (Figs. 21, 34, 97). No terminal expansion of the peduncle.
•25. Marine. Podocyathus, Kent. Small conical expansion at the
summit of the peduncle. Reproduction by one or two small tentaculate
gemmulae. -05. On marine Bryozoa and on Campanularia.

LITERATURE OF THE INFUSORIA (HETEROKARTOTA).

A very complete summary of the literature, and of our knowledge of the
Infusoria (Heterokaryota) up to the year 1887, will be found in —

Biitschli, 0. Infusoria. Bronn's Klassen und Ordnungen des Thierreichs, 1889.

The following memoirs have appeared since the publication of Biitschli's work,
and will be found of use to students wishing to obtain further information about
the group : —

Calkins, Cf. F. Studies on the Life-history of the Protozoa. Part I. Arch.

fur Entwickelungsmechanik, xv. Part II. Arch, fur Protistenkunde, i.

Part III. Biol. Bulletin, iii.
Le Dantec, F. La regeneration du micronucle'us chez quelques Infusoires cili£s.

Compt. Rend. 125.
Doflein, F. Studien zur Naturgeschichte der Protozoen — I. Kentrochona nebaliae;

II. Kentrochonopsis multipara. Zool. Jahrb. 10.

426 LITER A TURE OF THE INFUSORIA

Greenwood, M. On the Constitution and Mode of Formation of " Food Vacuoles "

in Infusoria, as illustrated by the History of the Process of Digestion in

Carchesium. Trans. Roy. Soc. 185.
On Structural Change in the Resting Nuclei of Protozoa. Journ.

Physiol. xx.
Giinther, A. Untersuchungen iiber die im Magen unserer Hauswiederkauer

vorkommenden Wimperinfusorien. Zeitschr. wiss. Zool. 65.
Hickson, S. J. Dendrocometes paradoxus. Part I. Conjugation. Quart. Journ.

Micro. Sci. 45.
Hoyer, H. Ueber das Verhalten der Kerne bei der Konjugation des Infusors

Colpidium colpoda. Arch. mikr. Anat. 54.
Ishikawa, C. Ueber eine in Misaki vorkommende Art von Ephelota und iiber

ihre Sporenbildung. Journ. Coll. Tokyo, 10.
Johnson, H. P. A Contribution to the Morphology and Biology of the Stentors.

Journ. of Morphol. 8.
Joukowsky, D. Beitrage zur Frage nach den Bedingungen der Vermehrung und

des Eintritts der Conjugation bei den Ciliaten. Verh. Ver. Heidelberg,

N.F. 6.
Koppen. Remarks on the Infusoria tentaculifera. Mem. Soc. Nat. Odessa, xiii.

2. (In the Russian language.)
Lillie, F. On the Smallest Parts of Stentor capable of Regeneration. Journ. of

Morphol. 12.
Maupas, E. Le rajeunissement Karyogamique chez les Cilies. Archiv. Zool.

Exp. 7.
Porter, J. Trichonympha and other Parasites of Termes flavipes. Bull. Mus.

Comp. Zool. 31. 3.
Prowazek, S. Protozoenstudien — 1, Bursaria truncatella und ihre Conjugation ;

2, Beitrage zur Naturgeschichte der Hypotrichen. Arb. Zool. Inst. "\Vien, 11,
Eompel, J. Kentrochona nebaliae: ein neues Infusor aus der Familie der

Spirochoninen. Zeitschr. wiss. Zool. 58.
Sand, fi. iStude monographique sur le groupe des Infusoires tentaculiferes.

Brussels, 1901.
Schewiakoff, W. The Organisation and Systematic Arrangement of the Infusoria

aspirotricha. Mem. Acad. Sci. St. Petersburg, T. 4, No. ix. (In the

Russian language.)
Ueber einige ekto- und en to - parasitische Protozoen der Cyclopiden.

Bull, de Moscow, 1893.

Wallengren, H. Ueber die totale Konjugation bei Vorticellina. Biol. Cen-
tral bl. xix.

ADDENDUM.
Roux, J. Faune infusorienne des Environs de Geneve, 1902.

INDEX

To names of Families, Sub-Families, and Genera '; to technical terms ;
and to names of Authors discussed in the text.

Abramis brama, 294, 339

abscess, 289

Acanthias acanthias, 339

— vulgaris, 339
Acanthis cannabina, 347
Acanthometra, parasites of,

423
Acanthospora, 201

— pileata, 201, 336

— polymorpha, 335

— repelini, 338
Acaathosporidae, 190, 201
acarine, 316, 337
Acephalina, 173, 175, 176,

192-196

Acerina cernua, 339
acerinae (PleistopJwra), 339
acervuliue tests, 58
Acheta abbreviata, 332
achetae-abbreviatae (Gre-

garina), 332
Achromaticidae, 265
A chromatic us, 265, 270

— vesperuginus, 270, 351
Achromatiu of meganucleus,

374

Acineta, 418, 425
Acinetaria, 418
Acinetina, 425
Acinetopsis, 422
acridiorum (Gregarina),

336, 337

Actiniaria, parasites of, 405
Actinobolina, 399
Actinobolus, 398, 399
Actinocephalidae, 190, 198,

200

Actinocephalinae, 199
Actinocephalus, 200

— acus, 200, 333

— acutispora, 337

— digitatus, 333

— dujardini, 332

— lucani, 200

Actinocephalus sp., 333

— steUiformis, 200, 333,
335, 336

— tipulae, 337
Actinomyxidia, 275, 298
Actinophrys, 161
Actinotricha, 412
actinotus (Gregarina}, 332
Actinurus neptunius, 325
Actitis hypoleucus, 347
acws (Actinocephalus), 200,

333

acwta (Glugea), 296, 343,
344

— (Gregarina), 337
acutispora (Actinocepha-
lus), 337

Acystis, 230, 270
Acystosporea, 241, 267-270
Acystosporidia, 264
^rfeZea, 229, 233, 234, 256,
257, 273

— akidium, 207, 233, 332,
335

— dimidiata, 233, 235, 332

— ?»es«#i, 206, 223, 224,
233, 337, 359

— ovata, 210, 213, 217,
222-224, 228, 230, 233,
332

— simplex, 233, 334

— tipulae, 233, 337
Addosina, 89, 91, 143
Aegyria, 400

aestivo - autumnal fever,

241

affinis (Hyalospora), 335
affinities of Sporozoa, 321-

323

Agelaeus phoeniceus, 347
Aggregate, 196, 272

— caprellae, 329

— coelomica, 188, 331

— conformis, 153, 331

427

Aggregata dromiae, 330

— nicaeae, 330

— portunidarum, 196, 329,
331

— praemorsa, 153, 329
Aggregatidae, 196
agilis (Legeria), 200, 333

— (Leptotheca), 293, 280,
281, 343, 344

— (Monocystis), 154-164,
193, 328

Agrion puella, 201, 332

Agrionidae, 201

ague, 241

akidium (Adelea), 207,

233, 332, 335
Akis acuminata, 332

— algeriana, 332

— sp., 192, 202, 207, 332
Alauda arvensis, 347
Alburnus alburnus, 295,

339

— mirandella, 339
Alcedo ispida, 347
Alciope sp., 196, 326
Alcyoncellum fungosum,

276, 328
algerianus (Cystocephalus),

202, 336
Alligator mississipiensis,

345

Allolobophoraterrestris, 327
Allomorphina, 144
^osa, 339

alpina (Barroussia), 332
alveolar sheath, 365
Alveolina, 110, 133, 137,

139, 143

Alveolinidae, 110, 143
-4?«<zra cuprea, 332
amarae (Gregarina), 332
amaroecii (Lankesteria),

339
^^waroectMm punctum, 339

428

INDEX

ambiguum(Myxosoma), 295

AnguUlula minima, 265

_4re«<ma interpres, 347

ambiguus (Myxoproteus),

Anguis fragilis, 232, 345

Argutinsky, 240, 246, 248

295, 342

anisogamy, 165, 184

.dricia latreillei, 315, 326

amitosis, 16, 293, 376

Annelids, parasites of, 404,

— midleri; 326

Amiurus melas, 339

406

armata (Corycdla), 174,

Ammodiscus, 85, 142

annular canal, 100

201, 334

Ammodytes tobianus, 339

annulatum (Selenidium),

arms, 371

Amoeba, 40, 322

327

Arthropoda, 205, 206, 207,

— pigmentifera, 325

anomala (Glugea), 278,

276, 297

— sagittae, 325

281, 286, 341, 342

Articulina, 93, 143

Amoebidium, 313, 314

Anomalina, 146

Artiodactyla, parasites of,

— cienkowskianum, 329,

Anopheles claviger, 249

403, 409

' 330, .331

— spp., 249, 250, 253,

Ascaris lumbricoides, 325

— crassum, 330

262, 332

— mystax, 276, 325

— moniezi, 329, 330

Anoplophrya, 401, 404

AscJiemonella, 141

— parasiticum, 313, 314,

Anser domesticus, 347

ascidiae(Lankesteria), 161,

329, 330, 336

Antherea pernyi, 332

170, 171, 172, 180, 185,

Amoebogeniae, 168

Anthocephalus, 199

194, 339

Amoebophrya, 423

Anthorhynchinae, 199

Ascosporidium blochmanni,

Amoebosporidia, 167, 177,

Anthorhynchus, 199

309

191

— sophiae, 199, 338

Asellus, Ciliate parasite on,

amoebula, 239, 243

Anthrenus museorum, 332

417

Amphibia, sporozoan para-

Anura, 275

Asellus aquations, 329

sites of, 208, 240, 275,

— parasites of, 404, 405,

Ashworth, 385

344, 345

406

Asida grisea, 333

Amphicorine, 145

anus, 368

— servillei, 333

Amphiglena mediterranea,

ape, 267, 350

asidae (Eirmocystis), 333

316, 326

aphidis (Neozygitis), 335

-4sio o<ws, 347

amphigony, 210

Aphis arundinis, 332

asperospora (Eertramia),

Amphileptina, 400

Aphodius nitidulus, 333

310, 311, 325, 326

Amphileptus, 400

— prodromus, 333

— (Glugea), 309

Amphimorphina, 145

Aphredoderus sayanus,

Aspidisca, 413

amphiont, 76, 210

340

Aspidiscina, 413

amphioxi (Branchiocystis),

aphroditae (Doliocystis),

Asplanchna priodonta, 325

238, 339

175, 177, 203, 326

— sp., 325

Amphioxus, 169, 194,238,

— (Monocystis), 175

Asporoblastea, 229

275, 339

Aphrodite, 203

Asporocystea, 229

Amphiporus cruciatus, 325

— aculeata, 177, 326

Asporocystidae, 229-231

Amphisia, 411

Aphrosina, 146

Assilina, 60, 147

Amphistegina, 53 (foot-

Apiosoma, 265, 269

association, 157, 177, 223-

note), 126, 146

— piscicola, 269

225, 273

Amphistomatidae, 141

^pis mellifera, 333

Astacus astacus, 329

Amphitrema, 81, 82, 141

Aplosporidia, 309-311

Astasia, 322, 323

Amphorella, 199

Aplosporidium, 311

Asterophora, 200

Amphoroides, 199

appendiculata (Cerato-

— elegans, 200, 336, 337

— polydesmi, 199, 332

myxa), 280, 342

— mucronata, 200, 336

anaemia, 209, 242

^>ws ajws, 347

Astrorhiza, 54, 83, 141

Anas boschas, 347

Arachnida, sporozoan para-

Astrorhizidae, 52, 141

— clypeata, 347

sites of, 206, 337

Astrorhizidea, 52, 55, 82,

— domestica, 347

aragonite, 54 (footnote)

- 139, 140, 141

Anchorina, 195

^Iranea diadema, 337

Astylozoon, 414

Ancistrodon piscivonis, 345

Archaediscus, 146

astyrae (Glugea), 333

.dTUJora, 195

Archer, 80

Athene noctua, 347

— sagittata, 195, 326

Archiacina, 100 (footnote)

Atherina hepsetus, 340

Ancyrophora, 190, 201

Archiannelida, sporozoa of,

Attacus pernyi, 333

— gracilis, 201, 333, 337

326

Attagenus pellio, 172, 333

— uncinata, 201, 333, 334,

archispore, 204, 220, 229

Audmiinia filigera, 203,

335, 337

archoplasm, 9

326

Ancy strum, 403

arcuata (Ceratomyxa), 340,

— lamarcki, 326

Angiosporea, 189, 196

342, 343

— sp., 175, 203

AnguiUa vulgaris, 340 ' arenaceous tests, 52

— tentaculata, 326

INDEX

429

Aves, sporozoan parasites

Bertramia asperospora, 310,

Bombyx mori, 288, 333

of, 347-350 (see also

311, 325, 326

bone, 277

Birds)

— capitellae, 309-311, 326

bone -marrow, 240, 242,

aviuin (Coccidium), 347-

Bibio marci, 176, 199, 333

248, 255

349

Bifarina, 144

Bonellia viridis, 196, 328

— (Lankesterella), 266

biformed tests, 58

bonelliae (Ophioidina), 196,

axis of construction, 87

Bigenerina, 114, 144

328

bigemina (Goussia), 339

Bonnet-Eymard, 230

Babesia, 269

— (Haemogregarina), 255,

Boophilus bovis, 262, 337

— bovis, 269, 350

267, 340

Borget, 423

— ovis, 351

— (Klossia), 331

Borlasia olivacea, 325

bacterifera (Gy (amoeba),

bigeminum (Coccidium),35Q

— octoculata, 325

270, 345

— (Piroplasma), 242, 255.

Bos taurus, 350

balani (Gregarina), 329

262, 269, 338, 350

Botdlina, 141

Balanoglossus kupjferi, 339

Billet, 246

Botdlus, 312

Balantidiopsis, 406

billeti (Haemogregarirui],

— daphniae, 330

Balantidium, 405, 406

346

— parvus, 329, 330

Balanus improvi-sus, 329

Biloculina, 53, 87, 89, 90,

— sp., 326

— perforatus, 253, 329

137, 142

— typicus, 312, 329, 330

— pusillus, 329

binary fission, 255, 271,

Bothriopsis, 200

— tintiunabulum, 329

291

— histrio, 200, 335

Balbiani, 275, 375

birds, sporozoan parasites

Bothrops sp., 345

Balbiania, 301, 308

of, 231, 241, 242, 268,

Bourne, A., 9, 379

balbianii (Sphaeromyxa),

347-350

Boveri, 9, 10, 44

287, 340, 342

black spores, 253, 274

bovis (Babesia), 269, 350

Balladina, 412

Blanchard, 207, 209, 232,

— (Haematoccus), 269

Bcmanella, 237

235, 237, 238, 308

Box boops, 340

— lacazei, 237, 332

Blanchardia, 312

— salpa, 340

barbel, 276

Blanchardina, 312

Brachionus amphiceros, 325

Barbus barbus, 296, 340

— cypricola, 312, 329, 330,

— oon, 325

— fluviatttis, 340

331

— pala, 325

barillet, 222

Blaps magica, 177, 333

— urceolaris, 325

Barroussia, 229, 233

— mortisaga, 175, 186,

Brachycoelium, 276, 325

— alpina, 332

187, 317

Brady, 53 (footnote), 112

— caudata, 226, 227, 233,

blast, 251

140

332

blastophore, 251

Brady ina, 142

— ornate, 230, 233, 234,

blattaeorientalis (Grega-

Branchiocystis, 238

335

rina), 336

— amphioxi, 238, 339

— schneideri, 233, 332

blattarum (Gregarina), 196,

Brassolis astyra, 333

Bathysiphon, 52, 141

197, 336

brevis (ffenneguya), 341

Batrachoseps attenuatus,

Blennius montagui, 340

brood chambers, 73, 112

270, 344

— ocellatus, 340

brown spores, 253

Bdelloidina, 142

— pholis, 340

Bryozoa, parasites on, 425

Beddard, 205

— sp., 279

bryozoides (Glugea), 276,

Bdoides, 190, 200

blenny, 240, 267

328

—firmus, 175, 201, 334

Blepharisma, 405

Btibalus sp., 350

— temm, 201, 334

Blepharocodon, 400

Bubo virginianus, 347

Belone acus, 340

Blepharocorys, 402

— sp., 347

— ftefotte, 340

blepharoplast, 11

budding, 291

— vulgaris, 340

Blepharoprosthium, 4 00

Budytes flavus, 347

beloneides (LobiancJiella),

Blepharosphaera, 400

Bufo agua, 294, 344

196, 326

Blepharostoma, 402

— lentiginosus, 294, 344

Benedenia, 234, 235, 257,

Blochmann, 79, 408

— marinus, 344

262, 267, 359

blochmanni (Ascosporidi-

— sp., 344

— e&ertfu, 234, 227-229,

um), 309

Bulimina, 126, 144

338

blood-corpuscles, effects on,

Buliminidae, 144

— octopiana, 234, 338

240, 242, 245

Bundle, 364

benign fevers, 241

Bolh'ina, 144

bungari ( Haemogrega rina ),

fteryi (Pilcocephalus), 335

bombycis (Glugea), 167, 276,

345

Bertram, 300, 309

288, 290, 291, 297, 333,

Bungarus fasciatus, 345

Bertramia, 309

334

Burrows, 116

43°

INDEX

Bursaria, 405, 406

Carabus violaceus, 201, 333 ! Ceratocorys horrida, 324

— conjugation of, 390

Caranx trachurus, 340

Oeratomyxa, 289, 293, 295,

Bursar idium, 406

Carassius carassius, 340

298

Bursarina, 406

Carchesium, 413, 416

— appendiculata, 280, 342

Buteo buteo, 347

cardnmnatosus (Rhopalo-

— arcuata, 340, 342, 343

— vulgar is, 347

cephalus), 320

— globuli/era, 342

Biitschli, 7, 50, 57, 111, 140,

Carcinus maenas, 196, 329

— inaequalis, 285, 340

163, 275, 322, 366, 379,

Qardudis carduelis, 347

— linospora, 287, 342

397, 401, 408, 421

— degans, 347

— pallida, 340

Butschlia, 396, 397, 400

Garine noctua, 347

— reticularis, 344

biitschlii (Ophryocystis),

Carinella annulata, 325

— spJiaerulosa, 286, 293,

187, 192, 233

carminophilous granules,

341, 343

182

— truncata, 287, 340

Caenomorpha, 408

carp, 276, 278, 290 (see

Oeratopogon sp., 191, 333

Gaenomorphnia, 408

also Gyprinus)

Ceratospora, 190, 194

calcareous tests, 53

Carpenter, 47, 54 (footnote),

— mirabilis, 194, 326

Calcarina, 57, 120, 146

57, 107, 122, 134, 135

Cercaria, 254

calcite, 54 (footnote)

Carpenteria, 146

Ceriodaphnia quadrangula,

Galcituba, 112, 143

Carterina, 142

329

Calidris arenaria, 347

cartilage, 277

— reticulata, 312, 329

Calkins, 387

caryolytica (Cyclospora),

Gervus capreolus, 301, 350

Gallidina parasitica, 326

208, 209, 221, 223, 225,

Cestodes, 254

Callionymus lyra, 340

227, 231, 273, 350

Cetonia aurata, 333

Calliphora vomitoria, 333

caryolyticum ( Aficrococci-

Chaenia, 399

Callyntrochlamys, 194

dium), 345

Chaetognatha, sporozoa of,

— phronintae, 195, 331

Caryotropha, 236

325

— sp., 331

— mesnilii, 206, 217, 223,

Ghaetopleura peruviana,

Calopteryx virgo, 201, 333

225, 236, 237, 327

317

cammillerii (Diplospora),

Cassidulina, 144

Ghalcides tridactylus, 345

231, 346

Cassididinidae, 144

Chamadeo vulgaris, 231,

Campanella, 416

casual infection, 167, 221,

345

Campascus, 141

263, 289

Chapman, 54 (footnote),

canal system, 56, 65, 126

Catopsilia eubule, 333

130 (footnote)

canalicular skeleton, 56

caudata (Barroussia), 226,

Charadrius alexandrinus,

Cancer pagurus, 329

227, 233, 332

347

cancer parasites, 320

— (Schneideria), 199, 337

— dubius, 347

Candeina, 138, 145

caudatum (Chlvromyxum),

— pluvialis, 347

Candona Candida, 312,

295, 344

Chasmatostoma, 402

329

Caullery and Mesnil, 190,

Chaussat, 265

Canis familiar is, 350

191, 205, 315

Chelidon urbica, 347

— (Piroplasma), 242, 270,

caullery i ( Ophryocystis) ,337

Chdidonaria urbica, 347

337, 350

Cavia cobaya, 350

Chelonia, 267

Cannabina linota, 347

Cavolini, 153

Chilifera, 402

cannibalism and infection,

Cecconi, 157, 161

Chilodon, 398, 400

221, 307

cell, discovery of, 1

G/iilodocona, 414

Canthocamptus minutus,

cement of tests, 52

Chilostomdla, 144

329

centrosome, 9, 186, 377

ChUostomdlidea, 115, 139

capitatus (Cometoides), 201,

centrosphere, 10

144

335

Cephalina, 169, 173, 174,

chinensis (Pileocephalus),

Gapitella capitata, 195, 205,

175, 176, 196-204

199, 335

309, 326

Cephalochorda, sporozoan

Ghiridota pdludda, 324

capitellae (Bertramia), 309-

parasites of, 339

Chironomus sp., 333

311, 326

oephalont, 174

Chiton fascicularis, 338

Capitdlides giardi, 326

Cephalopoda, parasites of,

— sp., 234, 338

Capra hircus, 350

206, 404

Ghitonicium, 317

Caprella sp., 329

Cepola rubescens, 287, 340

— simplex, 317, 338

caprellae (Aggregata), 329

ceratii (Hyalosaccus), 317,

chitonis (Minchinia), 227,

capsule, polar, 284

324

234, 236, 338

capsulogenous cell, 284

Ceratium fusus, 324

Ghlaenius vestitus, 333

Carabus auratus, 201, 333

— macroceros, 324

Chlamydodon, 400

— glabratus, 200, 333

— tripos, 324

Chlamydodonta, 400

INDEX

Chlamydomonas sp., 324

classification of Haemo-

Coccidium mitrarium, 208,

Chlamydospores, 152, 188,

sporidia, 264-270

233, 346

204, 304

— of Myxosporidia, 293

— oviforme, 206, 226, 227,

Chloris chloris, 347

— of Sarcosporidia, 308

232, 350

Chloromyxidae, 277, 285,

— of Sporozoa, 167

— perforans, 350, 351

288, 295

clausi (Gregarina), 331

— pfei/eri, 331, 347, 350

Chloromyxum, 295

clavellinae (Pleurozyga),

— proprium, 225-227, 272,

— caudatum, 295, 345

339

344

— diploxys, 275, 295, 337

— producta, 339

— raillieti, 232, 345

— fluviatile, 342

Clavulina, 114, 144

— ranarum, 344

— leydigi, 279, 282, 295,

Clemmys elegans, 345

— roscoviense, 347, 349,

339, 343, 344

Clepsydrina, 196

350

— mucronatum, 342

Clepsydrinidae, 183, 196

— salamandrae, 345

— perlatum, 293

Climacostomum, 406

— sardinae, 340

— quadratum, 340, 343,

Clitdlio, 298, 327

— schubergi, 206, 210-221,

344

Clivicola riparia, 347

228, 332

Chondrostoma nasus, 340

Clupea harengus, 340

— sinwndi, 331, 332

chromatin, 13

— pilchardus, 287, 340

— sp., 328, 331, 345, 346,

Chromatin of Meganucleus,

clupearum (Goussia), 340,

348, 350

374

341, 343

— tenellum, 232

chromatosphere, 282

Clymene lumbricalis, 326

— truncatmn, 347

chronic malaria, 252

Clymenella torquata, 193,

— viride, 351

chromosome, 18, 377

326

coccoidea (Pleistophora),

Chrysaliditw,, 144

— (Monocystis), 326

330

Chrysomela haemoptera,

Cnemidospora, 197

Coccothraustes, 347

333

— lutea, 198, 331

Coccus hesperidum, 333

— violacea, 333

Cnidaria, sporozoa of, 324

Codondla, 409

— populi, 333

Cob itis fossil is, 340

Coelomic Gregarines, 170

Chrysomitris spinus, 347

Coccidia (see Coccidiidea)

— parasites, 206

chydoricola (Coelosporidi-

coccidian phase of Grega-

coelomica (Aggregata), 188,

um), 311, 329

rines, 170

331

Chydorus sphaericus, 311,

Coccididae, 230

Coelopeltis lacertina, 231,

312, 329

Coccidiidea, 150, 165, 166,

345

Chytridiopsis, 317

167-168, 169, 172, 204-

Coelosporidium, 311

— socws, 317, 324, 333

238, 271-274

— chydoricola, 311, 329

cienkmoskianum (A moebidi-

coccidin, 218

Cohn, 4, 291, 309

um), 329, 330, 331

Coccidioides, 238

Colaeus rnonedula, 347

Cienkowsky, 385, 386

— immiiis, 238, 351

Coleophora, 200

cilia, 368

Coccidiomorpha, 271

Coleorhynchus, 200

ciliata (Myxocystis), 297,

coccidiosis, 209

— heros, 200, 335

328

Coccidium, 164, 205, 206,

Colepina, 399

Cinetochilum, 402

229, 231, 232, 233, 235,

Coleps, 365, 397, 399

Ciona in test iticdis, 171,172,

236, 237, 257, 285, 307

colorata (Pleistophora), 330

194, 339

— avium, 347-349

Colpidium, 401, 402

circumambient chamber,

— bigeminum, 350

Colpoda, 401, 402

105, 106

— colubri, 347

Coluber aesculapii, 345

Circus aeruginosus, 347

— cuniculi, 232, 350

— carbonarius, 345

Girratulus cirratus, 203,

— delagei, 232, 346

— corais, 345

204, 326

—falciforme, 213, 221, 230,

colubri (Coccidium), 347

cirrhatuli (Selenidium),

351

— (Haemogregarina), 346

326

— g aster ostei, 341

Columba domestica, 347, 348

Cirrhatulus filigerus, 326

— giganteum, 342

— ftwa, 348

cirri, 369

— hagenmulleri, 332

Colymbetes sp., 200, 201,

Cistudo europa^a, 232, 266,

— hyalinum, 333

333

267, 275, 345

— kermoganti, 346

cometa (Zygocystis), 193,

Claparede and Lachmann,

— lacazei, 206, 210, 213,

328

383, 400, 409

217, 230, 332

Cometoides, 201

classification of Ciliata, 396

— lacertae, 346

— capitatvs, 201, 335

— Coccidia, 229

— legeri, 346

— criidtus, 175, 201, 335

— of Foraminifera, 140

— metchnikovi, 207, 341

concentrated parasites, 277

— of Gregarinida, 191

— minutum, 208

conchite, 54 (footnote)

432

INDEX

Conchophthirus, 405
Condylostoma, 405, 406
cone of reception, 219,

259
conformis (Aggregata), 153,

331

Conger conger, 340
congri (Myxosporidium),

340
conjugation, 159, 160, 184-

188, 218, 219, 224-227,

250, 259, 291, 386

— of Bursaria, 390

— of Dendrocometes, 390

— of Holotricha, 389

— of Meganuclei, 390

— of Spirochona, 387

— of Vorticella, 387, 391
connective tissue, 277
Conochilus volvox, 326
Conorhynchus, 193
contagious infection, 1 67
contejeani (Thelohania),

276, 329

contractile fibres, 156, 180,
254

— vacuole, 152

— vacuoles of Foramini-
fera, 51

of Heterokaryota,

378

contractility, 281
Convoluta sp., 325
copula, 210
Coracias garrula, 348
cordis (Glugea), 340
Cor eg onus f era, 340

— lavaretus, 340
Coris giofredi, 340

— julis, 340
Cornish, 54 (footnote)
Cornuspira, 74, 86, 111,

142
Corondla austriaca, 345

— sp., 345

corps en barillet, 190, 222

— rosace, 222, 243
cortex, 365

Corvus americanus, 348

— corax, 348

— cornix, 348

— cor one, 348

— frugttegus, 348
Corycella, 201

— armata, 174, 201,334
Corynetes ruficollis, 333
Coskinolina, 142
Cothurnia, 413, 416
Coihurniopsis, 416
Coitus bubalis, 340

— scorpius, 297, 340

Cotyle riparia, 348
Crangon crangon, 329
Cr another idium, 398
crassum (Amoebidium), 330
Crawley, 181, 182
crayfish, 276

Crenilabrus mediterraneus,
340

— melops, 296, 340

— pavo, 340

— sp., 279, 285
Creplin, 153

creplini (Henneguya), 339
crescent, 239, 247, 248
Cretya, 230, 238

— neapolitana, 344
Cricetus cricetus, 350
crinitus (Cometoides), 175,

201 335
Cristellaria, 116, 137, 142,

144

Cristigera, 403
crocodile, 275
Crocodilia, 267
crocodilinorum (Haemo-

gregarina), 345
Crocodilits frontatus, 345

— sp., 345

crotali ( Haemogregarina),

345
Crotalus confluentus, 345

— sp., 345

cruciata (Ooussia), 344
Crustacea, 206, 320

— parasites of, 404, 414,
416, 417, 421, 422

— sporozoan parasites of,
329

Cryptochilum, 402
Cryptocystes, 275 - 277,

286, 288, 296, 299, 308
Cryptops hortensis, 198,

331

— punctatus, 331

— sp., 331

Cryptopus granosus, 346
crystalligera (Pyxinia),

334
crystalloides (Crystallo-

spora), 233, 236, 342
Crystallospora, 229, 233
Ctenodrilus serratus, 326
Ctenophora sp., 333
Cuculus canorus, 348
Cucumaria pentactes, 324

— planci, 324
Cuenot, 155, 159, 161
Culex, 249, 250, 253, 262,

268, 334

cuneata (Gregarina), 337.
359

Cuneolina, 144
cuniculi (Coccidium), 232,
350

— (Psorospermium),l%32
curvata (Gregarina), ^333
cuticle, 179
Cyclammina, 142
Cydidium, 401, 403
Cyclochaeta, 413, 414
Cydodypeina, 140
Cydodypeus, 71, 128, 130,

135, 147
Cyclodinina, 333
cydoides (Myxobolus}, 342
Cydopidae, 318, 319 {
Cycloposthium, 408, 410
Cyclops, 193, 318, 320

— gigas, 329

— inacrurus, 329
pJuderatus, 329

— rubens, 329

— sp., 329

— strenuus, 329
Cydopteridae, 275
Cydospora, 229, 231, 254

— caryolytica, 208, 209,
221, 223, 225, 227, 231,
273, 350, 351

— glomericola, 230, 231,
331

— sp., 331
cyclostomes, 275
Cyinbalopora, 119, 138,

145

Cyphoderia, 141
Cyphon pallidus, 197,

334
cypricola (Blanchardina),

312, 329, 330, 331
cypridis (Serosporidium),

312, 329
cyprini (Hoferellus), 296,

341

— (Myxobolus), 276, 278,
290, 296, 341

Cyprinodon variegatus, 341
Cyprinus carpio, 341

— rutilus, 296
Cypris Candida, 329

— jurini, 329

— ophthalmica, 329

— ornate, 329

— punctata, 329

— sp., 329, 330

— strigata, 329, 330

— •zn'dwa, 330

— mrms, 312, 329, 330
Cypsdus apus, 348

cyst, 152, 157, 183, 251,
272, 277, 301

— of Ciliata, 385

INDEX

433

cystal residuum, 159, 183

death, 396 | dimidiata (Adelea), 233,

220, 252

Decticus griseus, 334

235, 332

Gystignathus ocellatus, 294,

definitive host, 253

Dimorphina, 145

344

— sporoblast, 159

dimorphism, 59, 77, 134,

Cystobia, 189, 194

degeneration of cysts, 253,

255, 256

— Iwlothuriae, 178, 194,

274

Dinennympha, 418

324

de Hantken, 61

Dinoflagettata, 317

— irregularis, 194, 324

Delage, 288, 401

Dinophrya, 399

— schiieideri, 324

Delage and Herouard, 168

Dionejuno, 334

C'ystocephalus, 201

delagei (Coccidium), 232,

— vanillae, 334

— alffierianus, 202, 336

346

Diophrys, 412

Cystodiscidae, 294

— (Haemogregarina), 267,

Dipleurostyla, 412

Cystodiscus, 294

343

dipleurus (Myxobolas), 342

— diploxys, 275

de la Harpe, 61

Diplocystis, 169, 178, 184,

— immersus, 294, 344

Dendrocoelum lacteum, 325

194

Cystophrys, 80, 140

Dendrocometes, 418, 421

— WMy'or, 194, 334

Cytamoeba, 270

— conjugation of, 390 — minor, 194, 334

— bacteri/era, 270, 345

Dendrocometina, 421 — schneideri, 194, 336

— sp., 344

Dendrocopus minor, 348 Diplodinium, 410

cytocyst, 255

Dendrophrya, 141

Diplophrys, 48, 141

Cytopliagus, 230

Dendrosoma, 418, 421

Diplospora, 229, 231, 232

cytopyge, 368

Dendrosomina, 421

— cammillerii, 231, 346

Cytosporidia, 167

Dentalinopsis, 145

— Zacazei, 231, 347-350

cytostom, 366

depressa (Glugea), 296,

— laverani, 231, 345

340

— lieberkahni, 231, 236,

Dactylophoridue, 183, 190,

Dermacentor reticulatus,

345

198

270, 337

— mesnili, 231, 345

Dactyloph&rus, 190, 198

Dermestes, 174, 189, 201

— rivoltae, 231

— robustus, 198, 331

— peruvianus, 334

— sp., 344

Dactylosoma, 265, 270

— vulpinus, 200, 334 i/iploxys (Chloromyxum),

— ranarmn, 270

destruens (Glugea), 340

275, 294, 337

— splendens, 270, 345

deutomerite, 174

— (Cystodiscus), 275

Dallasia, 402

Diaphoro podon, 140

Discocephalus, 199

Damonia reeresii, 233, 346

Diaptomus gracilis, 330

discocodidis (Ophiaidina),

Danais erippus, 334

— salinus, 330

325

— yilippus, 334

— sp., 193, 318, 329, 330

Discocoelis tigrina, 325

dance of the sporoblasts,

Diaspora, 233

Discophrya, 401, 404

159

— hydatidea, 233, 236,

Discorbina, 123, 135, 145

Danilewsky, 239

332

Discorhynchus, 199

Dantteioskya, 266

Diazona violacea, 339

— truncatus, 199, 337

danilewskyi (Haemopro-

diazonae (Lankesteria), 339

Disematostoma, 402

teus), 253, 267, 268,

Dichilum, 402

dispar (Myxobohts), 296,

270, 334, 347-349

Dictyocysta, 409

341, 342

— (Halteridium), 266,268,

Dicystida, 176

Disporea, 231, 280, 283,

269, 347-349

Didesmis, 410

293, 298, 299

— (Myxidium), 275, 294,

Didinium, 396, 397, 399

Disporocystidae, 229, 230,

346

Didymophyes, 179, 198

231

— (Pleistophora), 345, 446

— gigantea, 180, 336

disporous, 283

Daphnia kaMbergiensis,

— leuckarti, 333

Dissosteira Carolina, 334

330

— longissima, 330, 331

Distaplia inagnilarva, 339

— longispina, 330

— paradoxa, 180, 198, 334

distapliae (Pleurozyga), 339

— maxima, 297, 330

Didymophyidae, 198

Distichopus sih-estris, 327

— ^wfer, 330

Diesing, 235 | Distomum, 254

— rectirostris, 330

diffuse infiltration, 278

distribution of Foramiui-

— reticulata, 330

digenetic, 166

fera, 138

— siwwi, 330

digestion, 380

Ditrema, 141

— sp., 254, 312

— physiology of, 380

divergens (Sphaerospora),

— vulgaris, 330

digitatus (A ctinocepJudus),

279, 340

daphniae (Botellus), 330

333

dizoic, 165

Dasytricha, 403

Dileptus, 397, 398, 400

Dodecaceria concharum,

davini (Gregarina), 334

— cyst of, 386

190, 203, 204, 326

28

434

INDEX

Doflein, 270, 271, 276, 277,

eclipidrili (Spermatopha-

Emys orbicularis, 346

278, 289, 291

gvs), 328

— fecte, 346

dog, 242 (see also Canis)

Edipidrilus frigidus, 240,

Enchelys, 396, 398

Doliocystidae, 175, 176,

267, 328

enchytraei (Monocystis),

200, 202

Edobia lapponica, 197,

328

Doliocystis, 202

334

Enchytraeus albidus, 328

— aphroditae, 175, 177,

ectoplasm, 156, 180, 254,

— (/atf>a, 328

203, 326

279, 365

— hegemon, 328

— dongata, 327

ectosarc, 365

encystment, 385

— heterocephala, 327

Ectospora, 168

endocyst, 157, 183

— pellncida, 202, 327

Ehrenbergia, 144

endogenous multiplication,

— polydorae, 327

Eimer, 205, 213

166 (see also Schizogony)

— sp., 327

Eimeria, 205, 213, 229-

— spore - formation, 275,

Donax sp., 206, 338

233, 235, 261, 272

285

d'Orbigny, 47

— falciformis, 230, 232,

endoglobular parasites, 239,

Dorcus parallelepipedus,

351

254

200, 334

— hirsuta, 334

endoplasm, 156, 182, 279,

Dormoy, 208

— hominis, 351

281

Drepanidium, 265

— wcpae, 230, 335

Endosphaera, 419, 422

— ranarum, 154, 239, 255,

— nova, 207, 223, 224,

Endospora, 168

270

229-231

endospore, 189, 220

— serpentium, 256, 266,

— schneideri, 230, 332

Endothyra, 142

345-347

— sp., 350

Endothyridae, 142

Dromia dromia, 330

— stiedae, 232

energid, 5

dromiae (Aggregata), 330

— trigemina, 331

Engraulis eticrasicholus,

Drymobius biforsatus, 346

Eimerian cyst, 222, 243

341

Dufour, 153, 169

— genera, 230

enhaemospore, 243

Dufouria, 200, 235

— phase, 213, 230

ensiform is ( Ureyarina),

Dujardin, 2, 47, 122

— stages, 270

339

dujardini (Actinocephalus),

Eimeridae, 230

Entdurus aequoreun, 341

332

Eimeriella, 231

enteritis, 209

— (Myxosoma), 294, 342

Einnocystis, 190, 197

Enteropneusta, sporozoan

Dysteria, 401

— aswfe, 333

parasites of, 339

Dysterina, 400

— gryllotalpae, 334

Entodinium, 409

Dysteropsis, 401

— polymorpJui, 179, 197,

" entoparasitic tubes," 318

Dytiscus sp., 201, 334

335

entozoic forms, 363

— ventricosa, 179, 336,

entzi (Molybdis), 344

cberthi (Benedenia), 227,

337

Epeira diadema, 337

229, 234, 338

Eisen, 267

Ephdota, 418, 425

— (Eucoccidimn), 338

Elasmobranchs, 275, 295

Ephelotina, 425

— (Klossia), 235

Eledone moschata, 236, 338,

Ephemera sp., 197, 334

— (Legeria), 338

359

ephemerae (Gamocystis),

— (Legerina), 338, 359

elegans (Asteroplwra), 200,

197, 334

echinatum (Selenidium),

336, 337

Epiclintes, 411

203, 204, 326, 327

— (Sphaerospora),'2$S,294,

epicyst, 157, 183

Echinocardium cordalum,

341

epicyte, 179

324

dlipsoides(Myx6bolus), 279,

epidemics, 276

— flavescens, 324

283, 287, 295, 296,

epimerite, 174, 179

— sp., 195

344

epispore, 189, 220

Echinocephalus, 198

Ellipsoidina, 144

Epistylis, 413, 416

Ecliinoderma, sporozoa of,

elliptica ( Ulivina), 253,

Epizoanthus glacialis, 324

324

326

epizoic forms, 363

Echinmmra, 190, 198

dmigata (Doliocystis), 327

equi (Piroplasma) 242,

— hispida, 175, 198, 332

— (Leptotheca), 342

270, 350

Echinorhynchus proteus,

Emberiza citrindla, 348

Equns cabnllus, 350

325

— miliaria, 348

Erimyzon sucetta, 341

Echinospora, 233

— projer, 348

erippi (Glugea), 334

— labbei, 227, 233, 236,

U?« yrfa #ra M os«, 346

Erithacus luscinia, 348

332

Emys europaea, 346

— phoenicurus, 348

— ventricosa, 332

— lutaria, 266, 267, 275, — rubecula, 348

Echiurus pattasi, 193, 328

346 Esarhabdina, 204

INDEX

435

Esox lucius, 282, 291, 341
eubules (Gluyea), 333
Eucoccidium, 234, 235

— eberthi, 338

— octopiunuin, 338
Euglena, 180, 213, 322
euglenoid, 322

— movements, 181, 211,
245

Euglypha, 52, 79, 140
Eugregarinae, 175, 192
Eulalia punctifera, 326
Eunectes murinus, 346
eunicae (Selenidium), 326
Eunice harassei, 326
Euplotes, 411, 412
Euplotina, 411
Eupolia delineata, 325
Eurycercus lamellatus, 330
Euspora, 197

— fallax, 197, 336
Ew'ing, 246, 248
exiguus (Afyxobolus), 339,

342

exogenous, 166
Exosporidia, 150, 167, 312-

316
Exosporidium, 316

— marinum, 316, 337
exotospore, 243, 251

Fabricm sabella, 316, 326
Fabularia, 143
falcatula (Sarcocystis), 348
falciform body, 161
falciforme (Coccidium),

213, 221, 230, 351
falci/iyrmis (Eimeria), 230,

232, 351

— (fJregarina), 205, 230
Falco tinnunculus, 348
AtWoa; (Euspora), 197, 336
fat- body, 207
Feiuberg, 321

Fdis domestica, 350
fertilisation, 219, 227
fertilisation-spindle, 219,

227, 259, 274
fever, 241
filament, polar, 284
Filaria, 154
firmus (Belmdes), 175, 201,

334

fish, parasites of, 398
fishes, sporozoan parasites

of, 240, 297, 339-344
fish-psorosperms, 275
fissidens (Sciadopk&ra), 338
fission, 255, 271, 291, 382

— in Jfyalopus, 82

— in Lieberkiihnia, 82

fission in Lecythium, 82

— in Trichosphaerium, 82
Flabellina, 145
flagellated body, 239
Flagellata, 211, 322, 323
flagellum, 216, 226, 250,

257-259, 270
flava (Gregarina), 339
Flemming, 4, 16, 27
Flesus passer, 341
fluviatile (Chloromyxum),

342

foliacea (Monocystis), 326
Folliculina, 407
Fonquet, 386
Fontaria viryiniensis, 331
food of Foraminifera, 50

— of Heterokaryota, 361
food-vacuole, 152
Foraminifera, 47, 322
Forficula auricularia, 196,

334
form of Heterokaryota, 362

— of test, 58
Foruasini, 115
fragmentation of Mega-
nucleus, 372

fraiicisci (Gamocystis), 334

— (Ophryocystis), 192, 332
free parasites, 241, 254,

277

frenzeli (Pyxinia), 172, 333
freundi (Spermatophagus),

328
Fringilla canaria, 348

— carduelis, 348

— coelebs, 348

— montifringilla, 348
Fritsch, 309

frog, 208, 240, 270 (see

also Rana)
Frommaun, 7
Frondicularia, 115, 144
Frontonia, 401, 402
fusiformis (Nematoides),

283, 329, 331
Fusulina, 133, 137, 139,

146
Fusulinidae, 146

Gadus pollachius, 341
Galerita cristata, 348
Galeus galeus, 286, 293,

341

(Julius domesticus, 348
gamete, 156, 159
gametes of Coccidia, 215-

220, 225-227, 273

— of Foraminifera, 76

— of Gregarines, 159, 184-
188, 273

gametes of Haemosporidia,

250, 257-259
gametocyte, 157, 215
gametocytes of Coccidia,

215-218, 223-225, 272-

273

— of Gregarines, 184, 272,
273

— of Haemosporidia, 247-
253, 256-259

gametogenous mononts, 210
gammari (Serosporidium),

330

Gammarus locusta, 330
Gammarus, ciliate, parasites

on, 414, 417, 421

— pulex, 292, 312, 330

— puteanus, 330

— sp., 285
Gamocystis, 197

— ephemerae, 197, 334

— francisci, 334

— tenax, 197, 334
Gardiner, 5

Garrulus glandarius, 348
gasterostei (Coccidium), 341
Gasterosteus aculeatus, 278,
296, 341

— pungitius, 296, 341
- sp., 294, 341

Gastropacha tieustria, 334
Gastropods, parasites of,

404

Gastrostyla, 412
Gaudryina, 144
Gavialis gangeticus, 346
gemmation, 385
Gemmula, 384
Geneiorhynchus, 200

— monnieri, 175, 200, 335
geological distribution of

Foraminifera, 139
geophili (Rhopalonia), 198,

331, 332
Geophilidae, 198
Geophilusferruginosus, 331

— sp., 331

Geotrypes stereorarius, 180,
198, 334

Gephyrea, sporozoan para-
sites of, 328

Gerda, 414

giardi (Thelohania), 329

gibbosum (Zygosoma), 193,
328

gigantea (Didymophyes),
180, 336

— (Gluyea), 340

— (Pfeifferdla), 342

— (Porospora), 151, 182,
196, 330

436

INDEX

giganteum (Coccidiiim),34£

— (Myxidium), 283, 343
girardini (Glugea), 341
Girardinus sp., 341
Glandiceps hacksi, 339
Glaucoma, 401, 402
Globidium leuckarti, 350
Globigerina, 51, 117, 138,

139, 142, 145

— ooze, 138
Globigerinidea, 117, 139,

145

globosus (Myxdbolus), 341
globulifera (Ceratomyxa),

342
glomericola (Cydospora),

230, 231, 331
jllomeris guttata, 230, 331

— marginata, 230, 331

— ornata, 230, 331

— sp., 198, 207, 230, 231,
331

Glossatella, 416
Glossiphonia complanata,
328

— sexoculata, 328
Glugea, 285, 297

— ocwta, 296, 343, 344

— anomala, 278, 281, 286,
341, 342

— asperospora, 309

— astyrae, 333

— bmnbyds, 167, 276, 288,
290, 291, 297, 333,
334

— bryozoides, 276, 328

— cordis, 340

— depressa, 296, 340

— destruens, 348

— erippi, 334

— evbules, 333

— gigantea, 340

— girardini, 341

— helminthophthora, 276

— jwnonis, 334

— laverani, 276, 327

— fopfot, 277, 292, 342

— lophocampae, 335

— lysimniae, 335

— marionis, 340

— microspora, 341, 342

— ovoidea, 286, 340, 342

— periplanetae, 336

— punctifera, 341

— sp., 325, 332-338, 342,
343

— stephani, 341

— s^n'cte, 336, 337

— thysanurae, 336, 337

— vanillae, 334

— varians, 337

Glugeidae, 238, 289, 292,

296, 297, 308
Glycera, 177, 194, 326
glycogen, 289
Gobio fluviatilis, 341

— groito, 341
Gobius albus, 341

— bicolor, 341
— fluviatilis, 341

— minut-us, 341

— paganellus, 341
Gongylus ocdlatus, 231,

346

Gonobia, 230, 238
Gonospora, 194, 316

— longissima, 326

— sparsa, 177, 326, 327

— terebdlae, 190, 194, 326,
327

— varia, 326
Gonostomum, 412
yoronowitschi (Sciado-

phora), 338
Goussia bigemina, 339

— c£wpearMwz,340,341, 343

— cruciata, 344

— tocida, 339, 343

— minuta, 344

— motdlae, 236, 342

— thelohani, 342

— variabilis, 340, 341, 342
gracilis (Ancyrophora), 201,

333, 337

granulosa (Gregarina), 334
Grassi, 210, 240, 250, 252,

253, 261, 262, 266
Greef, 414
Greenwood, 380
Gregarina, 153, 169, 177,

190, 196

— achetae-abbreviatae, 332

— acridiorum, 336, 337

— actinotus, 332

— acuta, 337

— amarae, 332

— Jo&mi, 329

— blattaeorientalis, 336

— blattarum, 196, 197,
336

— dausi, 331

— cuneata, 337, 359

— cwmito, 333

— da-vim, 334

— ensiformis, 339

— falciformis, 205, 230

— flava, 339

— granulosa, 334

— gryllorum, 334

— hyalocephala, 337

— jidipusilli, 332

— lagenoides, 335

Gregarina laucournetensis,
184, 336

— locustaecarolinae, 334

— Zowf/a, 175, 337

— longirostris, 337

— - 'macrocephala, 334, 335

— megacepliala, 332

— melolonthaebninneae,
335

— microcepJutla, 334

— munieri, 181, 333, 337

— mystacidarum, 335

— <wate, 196, 334

— panchlorae, 336

— passalicornitti, 336

— philica, 335

— podurae, 336

— potydesmivirginiensis,
331

— polymorpha, 196, 337,
359

— pterotracheae, 338

— sa/^«e, 339

— scarabaeirelicti, 337

— soror, 336

- sp., 325, 327, 328, 329,
330, 331, 339

— spionis, 317

— statirae, 337

— sfetwi, 337, 359

— temiitis, 337

— ralettei, 331
Gregarinida, 168-204, 271-

274, 322, 323
Gregarinidae, 183, 190,

196

gregariniform stage, 246
gregarinoides (Schizocystis),

191, 333
Grew, 2

Gromia, 49, 54, 140
Gromiidea, 52, 79, 140
growth of tests of Fora-

minifera, 54

Gruber, 79 (footnote), 373
gryllorum (Gregarina), 334
Gryllotalpa gryllotalpa sp.,

334
gryllotalpae (Einnocystis),

334
Gryllus campestris, 334

— domesticus, 334

— sp., 334

— sylvestris, 334
gudgeon, 207
Giinther, 410

Gurley, 276, 283, 294, 295
Gurleya, 285, 297

— tetraspora, 297, 330
Gymnospora, 236

— nigra, 337

INDEX

437

gymnospore, 152, 165, 272

Haemogregarina magna,

helminthophthora (Pleisto-

Gymnosporea, 189, 196

267, 345

phora), 276, 325

gymnospores of Coccidia,

— mesnili, 346

Helops striatus, 201, 202,

204, 230

— metchnikovi, 346

334

— of Gregarines, 188

— mocassini, 345

Henle, 153, 154

— of Haeraosporidia, 239,

— najae, 346

Henneguya, 286, 296

261

— nasuta, 240, 267, 328

— brevii, 341

— of Sarcosporidia, 304,

— platydactyli, 346

— creplini, 339

306

— pythonis, 346

— kolesnikovi, 340

Gymnosporidia, 264

— rara, 346

— linearis, 339, 343

Gynmostomata, 396

— simondi, 267, 344

— macrura, 341

Gypsina, 146

— sp., 345

— media, 341

Oyrinus natafor, 174, 201,

— stepanovi, 266, 267, 346

— monura, 340

334

— stepanoviana, 346

— psorospermica, 288, 296,

— sp., 233, 334

— zamenis, 347

341, 343

Gyrocoryna, 408

haemogregarine, 246, 254

— schizura, 341

Haemogregarinidae, 265

— sp., 340

Hdbia ludoviciana, 348

Ilaemomenas, 267

— sp., 342

habitat of Coccidia, 205,

Haemoproteus, 250, 257-

— strongylura, 344

210

259, 265, 267-269

— tennis, 339

— of Gregarinida, 169-172

— danileivskyi, 253, 267,

hepseti (Leptotheca), 340

— of Haemosporidia, 240

268, 270, 334, 347-349

hereditary infection, 167,

— of Myxosporidia, 276-

Haemosporea, 241, 265,

263, 290

278

274

heros (Coleorhynchus), 200,

— of Sarcosporidia, 300-

Haemosporidia, 150, 154,

335

302

165, 166-168, 172, 239-

Herpetodryas carinata, 346

habits of Heterokaryota,

270, 323

Herpobdella atomaria, 328

361

Hagenmiiller, 320

Hertwig, R., 11, 12, 14, 80,

Haeckel, 210, 409

hagenmitileri (Coccidium),

371, 376, 425

haeckeli (Ophioidina), 331

332

heterocepJuila (Doliocystis),

Haemamoeba, 265, 267,

— (Ophryocystis), 336

327

268

Hake, 153, 204

heterocirri (Haplospori-

— kochi, 267

Haliphysema, 84, 141

dium), 311, 326

— metchnikovi, 270

Hallezia, 425

Heterocirrus viridis, 311,

— sp., 349

Ifalteria, 409

326

— subimmaculata, 270

flalterididae, 265

Heterocope sp., 330

haemamoebae, 254

Halteridium, 257-259, 265,

heteroica(Pleistophora),347

ffaemamoebidae, 265

267-269

Heterostegina, 127, 129,

Haemaphysalis leachi, 270,

— danilewskyi, 266, 268,

147

337

269, 347-349

Heterotricha, 405

Haemapium, 270

Halterina, 408

heterotype division, 27

— riedyi, 270, 344

hankini (Haemogregarina),

Hexactinomyxon, 298

Haematid, 240

346

— psammoryctis, 298, 328

Haematococcus bovis, 269

Haplocyta, 175

Hexapoda, sporozoan para-

Haematophyllum, 239

Haplophragmium, 142

sites of, 332

Haementeria officinalis, 328

Haplosporidia, 150, 167,

Hickson, 376

haemocoele, 252

168, 309-311, 320

Himantarium gabrielis, 331

Haeraocytozoa, 240

Haplosporiditim, 311

Hintze, 250, 254, 259, 265,

haemoglobinuria, 242

— heterocirri, 311, 326

270

Haemogregarina, 254, 261,

— scolopli, 311, 327

Hippocampus brevirostris,

265, 266

ffaplostiche, 142

341

— bigemina, 265, 267, 340

Hastatella, 414

Hippocrepina, 142

— billeti, 346

Hastigerina, 138, 145

Hirmocystis, 197

— bungari, 345

Hauerina, 143

hirsuta (Eimeria), 334

— colubri, 346

Hauerinidae, 93, 110, 143

Hirudinea, sporozoan para-

— (frocodil'inorum, 345

heeri (Pileocephalus), 175,

sites of, 328

— crotali, 345

199, 336

Hirundo rustica, 348

— delagei, 267, 343

Heidenhain, 9, 13

hispanus (Oocephalus), 282

— hankini, 346

helicina (Klossia), 205, 207,

335

- labbei, 345, 346

208, 223-225, 235, 338

hispida (Echinomera), 175,

— lacazei, 267, 346

Helix spp., 207, 208, 338

198, 332

438

INDEX

histophilum (Myxidium),

Hyalospora affinis, 335 | insects, Ciliate parasites of,

342

— reduvii, 336

405

Histosporidia, 167, 277

— roscoviana, 197, 336

insignis (Lophocephalus),

Histozoa, 277

Hybognathus nuchalis, 341

201, 334

Histrio, 421

Hydaticus sp., 200, 335

intermediate body, 23

— (Bothriopsis), 200, 335

hydatidea (Diaspora"), 233,

-host, 167, 239, 249, 253,

Hofer, 276, 278

236, 332

254, 263

Hoferdlus, 296

Hydatina senta, 326

— skeleton, 57

— cyprini, 296, 341

Hydra, Ciliate parasites on,

Involutina, 142

Hoferia, 296

411, 414

iodinophilous vacuole, 289

Holland, 116

Hydrachnid, 338

irregularis (Cystobia), 194,

holopedii (Pleistophora),

Hydractinia, Ciliate para-

324

330

sites on, 403

Ischnochiton minator, 317

Holopediwn gibberum, 330

Hydrcbius sp., 175, 201,

Ishikawa, 373, 374, 424,

Holophrya, 396, 397, 398

335

425

Holophryina, 398

Hydroids, Ciliate parasites

isogamy, 165, 184, 188,

Holosticha, 411

on, 421, 422

273

Holothuria forskalii, 194,

Hydrophilns piceus, 200,

isomorphic (Lituolidae),

324

335

85, 137

— impatiens, 324

Hydrous caraboides, 335

isomorphism, 137

— nigra, 324

— sp., 201, 335

Isospora, 232

— polii, 324

Hyla arbarea, 344

— rara, 232, 338

— hibulosa, 178, 194, 324

— sp., 344

— sp., 345

holothuriae(Oystobia), 178,

Hymenostomata, 401

Jsosporidae, 230

194, 324

Hyperammina, 55, 82, 83,

Isotricha, 401, 403

Holotricha, 396

84, 141

Isotrichina, 403

Holotricha, conjugation of,

hypertrophy produced by

lynx torquiila, 348

389

parasites, 170, 208, 241

Homarus gammarus, 330

Hypocoma, 420, 422

Jaculella, 141

hominis (Eimeria), 351

Hypocomina, 422

Jasmineira elegans, 316.

Homo sapiens, 351

Hypotricha, 410

326

homotype division, 27

jaundice, 242

Hooke, 1

Idalina, 89, 92, 136, 143

Joenia, 418

Hoplitophrya, 404

ignotum (Triactinomyxon),

Joukowsky, 387

Hoplocephala bicornis, 334

298, 327

Joyeuxdla, 316

Hoplorhynchus, 201

Heonema, 398, 399

— toxoides, 316, 327

— oligacanthus, 333, 201

immaculatnm (Plasmo-

juli (Stenopkora), 198, 332

Hormosina, 142

dium), 267

julipusiUi (Gregaritui), 332

horse, 242 (see also Equus)

immersus (Cystodiscus),

Julis giofredi, 341

— Ciliate parasites of, 364,

294, 344

Julus margiiiatus, 331

400, 402, 403, 410

immitis (Coccidioides), 238,

— pusillus, 332

host-cell, effect on, 170,

351

— sabulosus, 198, 332

208, 241, 245

— (Sarcocystis), 351

— terrestris, 198, 332

— penetration of, 211, 245

Imperforata, 54 (footnote)

junonis (Glugea), 334

Hoyer, 377, 389

inaequalis (Ceratomyxa),

hueti (Sarcocystis), 305, 351

285, 340

Kachuga tectum, 346

Huxley, 400

— (Myxobolus), 296, 343,

Karyamoeba, 318

Hyale pontica, 330

344

— renis, 318, 345

hyaline Foraminifera, 64

incubatory pouches, 384

karyokinesis, 16

hyalinum (Coccidium), 33S

incurvata (Sphaeromyxa),

Karyolysus, 261, 265, 266

hyalocephala (Gregarina),

340 — lacertarum, 241, 256,

337

incurvatum (Myxidmm), 266, 346

Hyaloklossia, 231

340, 343, 344

— sp., 346

— lieberkiihni, 236

infection, methods of, 167,

Karyophagus, 208, 230.

— pelseneeri, 206, 236, 338

221, 249, 262, 263, 289,

270, 309

Hyalopterus arundinis, 335

307, 308

— ranarum, 270, 344

Hyalopus, 48, 52, 76, 80,

initial polymorphism, 92,

— salamandrae, 270, 345

140

99, 106, 136

— tritonis, 270

Hyalosaccus, 317

inoculative infection, 167

Karyosome, 156, 183, 210,

— ceratii, 317, 324

inopinata (Sycia), 175,

212, 216, 218, 225, 259,

Hyalospora, 197

203, 324, 326

282

INDEX

439

Kelly, 54 (footnote)

Lacerta agilis, 267, 346

Leger, 161, 169, 176, 184,

Kendall, 54 (footnote)

— muralis, 266, 300, 346

188, 191, 206, 226, 229,

Kent, 371, 384, 409, 415,

— ocdlata, 346

230, 273, 276

416

— sp., 241, 266, 346

Leger and Duboscq, 187

Kentrochona, 413, 414

— viridis, 346

Ugerdla, 230, 231, 272

— nuclei of, 377

lacertae (Coccidium), 346

— nova, 229, 331

Kentrochonopsis, 414

lacertarum (Karyolysus),

— testiculi, 230, 331

Keramosphaera, 143

241, 256, 266, 346

Legerellidae, 230

KeramospJuieridae, 143

lacryma (Monocystis), 329

legeri (Coccidimn), 346

kermoganti (Coccidium),

Lacrymaria, 396, 397, 398

— (Monocystis), 333

346

Lagena, 116, 142, 144

Legeria, 200, 234, 235

Kerona, 411

Lagenidae, 144

— agilis, 200, 333

kidney, 207, 208, 240,

Lagenidea, 115, 139, 144

— eberthi, 338

275, 277, 278, 290

lagenoides (Gregarina), 335

— octopiana, 330

kinoplasm, 9

Lagenophrys, 417

Legerina, 359

Kloss, 205, 236

Lagis koreni, 316, 327

— eberthi, 338, 359

Klossia, 226, 229, 235

Lagynus, 398

— octopiana, 338, 359

— bigemina, 331

Lamna cornubica, 342

Leidyonella, 417

— eberthi, 235

Lang, 210, 381

Lembadion, 403

— helicina, 205, 207, 208,

Lanius spp., 348

Lembus, 403

223-225, 235, 338

Lankester, 84, 154, 234,

Lepadogaster gouani, 342

— octopiana, 235, 236,

239, 243, 365, 370, 397,

Lepisma saccharina, 335

338

409

Leptocephalus conger, 342

— swor, 236

Lankesterdla, 254, 256,

Leptodactylus ocellatus, 344

Klossidae, 230

259, 265

Leptodora, 136

Klossiella, 236

— avium, 266

Leptotheca, 293

— muris, 236, 351

— minima, 265

— agUis, 280, 281, 293,

Koch, 262, 301, 305, 306

— monttis, 265, 267, 345

343, 344

kochi (Haemamoeba), 267

— ranarum, 239, 253-257,

— elongata, 342

— (Plasmodium), 267,

260, 261, 265, 267, 270,

— hepseti, 340

350

345

— ohlmacheri, 344, 345

kolesnikovi (Ifenneguya),

Lankesteria, 194

— parva, 343

340

— • amaroecii, 339

— perlata, 293, 339

Kolliker, 153

— ascidiae, 161, 170, 171,

— polymorpha, 343

Ktillikerella, 196

172, 180, 184, 185, 194,

— ranae, 293, 345

— staurocephali, 196, 327

339

— renicola, 293, 343

Kollikeria, 196

— diazonae, 339

Lepus cuniculus, 350

Korotnef, 276, 320

— leuckarti, 325

— timidiis, 350

Kossel, 267

— sp., 339

Leucisctts cephalus, 342

Lathonura rectirostris, 330

— erythrophthalmus, 342

Labbe, 155, 167, 168, 191,

Latrunculus albtts, 342

— funduloides, 342

194, 205, 218, 229, 231,

la ucoumetensis ( < l raja -

— phoxinus, 342

232, 233, 235, 238, 240,

rina), 184, 336

— rj<^tw, 294, 296, 342

256, 264, 269, 297, 315,

Laveran, 154, 207, 208,

Leuckart, 205

320

232, 239, 240, 242, 265,

Ze uckarti ( Didymophyes),

labbei (Echinospora), 227,

267, 270

333

233, 236, 332

Laveran and Mesnil, 175,

— (Globidium), 350

— (Haemogregarina), 345,

208, 233, 240, 255, 291, — (Lankesteria), 325

346

301, 303, 305, 306, 307

Leucocytes, 240, 247, 25i>

Labeo niloticus, 296, 342

laverani (Diplospora), 231,

278

Labrus festivus, 342

345

Leucophrydivm, 402

— turdus, 287, 342

— (Glugea), 276, 327

Leucophrys, 401, 402

lacazei (Bananella), 237,

Laverania, 261, 265, 267

Leydig, 4, 7, 153, 154

332

— malarias, 243-254, 267,

leydigi (Chloromyxum),

— (Coccidium), 206, 210,

332, 351

279, 282, 295, 339, 343,

213, 217, 230, 332

— ranarum, 270, 345

344

— (Diplospora), 231, 347-

Lecanium hesperidum, 335

— (Monocystis), 326

350

Lecythium, 82, 140

Libellula, 175, 200

— (Haemogregarina), 267,

Le Dantec, 393

Libdlulidae, 335

346

le danteci (Rhaphidospora),

Lieberkiihn, 153, 205, 231,

Lacazina, 143

317, 336

275, 406

440

INDEX

lieberkiihni (Diplospora),

231, 236, 345
— (HyaloJdossia), 236
Lieberkiihnia, 48, 82, 140
lieberk'iihnii (Myxidium),

281, 282, 283, 291, 294,

297, 304, 342
Lieberkiihnina, 408
Licnophora, 413, 414
Licnophorina, 414
Lignieres, 270
Ligurinus Moris, 348
Lillie, 393
Limax cinereo-niger, 232,

338

Limnetis sp., 330
Limnobia sp., 197, 335
Limnodrilus daparedi-

anus), 297, 328
Limnophilus rhmnbicus,

201, 335

Limnophilus sp., 336
Lindemann, 232
lindemanni (Sarcocystis),

351
linearis (Henneguya), 339,

343

Linens gesserensis, 325
Lingulina, 144
Lingulinopsis, 145
linospora (Ceratomyxa),

287, 342

lintoni (Myxobolus), 341
Liocephalus liopygus, 327
Lionotus, 400
Lithobius castaneus, 332
—forficatus,175, 198,206,

210, 221, 332

— hexodus, 332

— impresses, 233, 332

— martini, 226, 233,
332

— mutabilis, 233, 332

— pilicarnis, 332

— pyrenaicus, 332

— sp., 164, 205, 237
Lithocystis, 194

— schneideri, 194, 195,
324

Lituola, 142
Lituolidae, 52, 142
Lituolidea, 52, 85, 138

(footnote), 140, 142
Lobianchella, 196

— beloneides, 196, 326
Locusta Carolina, 335
locustaecarolinae ( Gregar-

ina), 334
Loftusia, 138 (footnote),

142
Loftusidae, 142

longa (Gregarina), 175,

337
longicollis (Stylorhynchus),

175, 186, 202, 324, 333
longirostris (Gregarina),

337
longissima (Didymophyes),

330, 331

— (Gonospora), 326
fop&w (Glugea), 277, 292,

342
Lophius budegassa, 342

— piscatorius, 277, 295,
342

— sp., 280

Lophocampa flavostica, 335
lophocampae (Glugea), 335
L'ophocephalus, 201

— insignis, 201, 334
Lophomonas, 417
Lophorhynchus, 201

Zote vulgaris, 282, 291,

342

Loxocephalus , 401, 402
Loxophyllum, 400
lucani (Actinocephalus),

200

— (StephanopJwra), 200,
334

Lucanus parallelepipedus),

200, 335

Lucernaria auricula, 324
? ucernariae ( Psorosper-

mium), 324

/Mcida (Goussia), 339, 343
Lucioperca lucioperca, 342

— sandra, 342

Liihe, 232, 235, 267, 300,

305
lumbrici (Monocystis), 155,

327, 328

Lumbriconereis, 327
Lumbricus, 155, 193

— agricola, 328

— herculeus, 328

— oto&w, 328

— rubellus, 328
Luscinia phoenicurus, 348

— wr«, 348

ftttez (Cnemidospora), 198,

331

Lutz, 256, 266
Lycosella, 199
Lymphosporidium, 312

— truttae, 312, 343
Lynceus sphaericus, 330
lysimniae (Glugea), 335

J/, abbreviation indicating
diameter of megalosphere,
89

m, abbreviation indicating

diameter of microsphere,

89

Macacus sp., 350
Macallum, 242, 257, 259
M'Donald, 138
Machilis cylindrica, 335
macrocephala (Gregarina),

334, 335
macrocystis ( Thelohania),

331
macrogamete, 215, 223-

227, 250, 256-259
macrogametocyte, 215, 217,

218, 223, 227, 248, 250,

256, 259

macrohaemozoite, 256
macroinerozoite, 256
macronucleus, 372
Macropus penicillatus, 350
macroschizont, 256
macrosporozoites, 256
tnacrura (Henneguya), 341
magna (Haemogregarina),

267, 345

— (Monocystis), 155, 157,
327, 328

major (Diplocystis), 178,

194, 334
malaria, 241
ma^ariae (Lai-crania), 243-

254, 267, 332, 351

— (Oscillaria), 239

— (Plasmodium), 243-254,
267, 332, 351

malarial parasite, 154, 229,
239

maldaneorum (Pterospora),
193, 194, 326, 327

Malpighi, 2

mammalia, sporozoan para-
sites of, 233, 241, 350,
351

man, sporozoan parasites
of, 232, 351

— Ciliate parasites of, 364
Mannaberg, 248
Marchiafava and Celli, 239
Marginulina, 144
marinum (Exosporidium ),

316, 337

marionis (Glugea), 340

MarsipeUa, 141

Mary no, 410

masked fever, 242

masovica (Sphaerospora),
294, 339

Massilina, 89, 143
! Mastigamoeba, 321, 323

Mastigophora, 321, 322
! maturation, 218, 225, 259

INDEX

441

Maupas, 365, 370, 376,

metchnikavi (Coccidium),

mitis (Monocystis), 324,

385, 386, 392

207, 341

327

meal-worm, 150, 196

— (Haemamoeba), 270, 346

Mitosis, 16, 377

Meandropsina, 107 (foot-

Metopus, 405

mitrarium (Goccidiwn),

note), 143

Metschnikoff, 168, 239

208, 233, 346

Mechanites lysimnia, 335

microcepliala (Gregarina),

mobttis (Monocystis), 329,

media (ffenneguya), 341

334

330

medulla, 366

Micrococcidium caryoly-

mobiuszi (Pyxinia), 332

megacephala (Gregarina),

ticum, 345

mocassini (Haemogregar-

332

micr ogam etc, 215-217, 219,

ina), 345

megalosphere, 63

223-227, 250, 256-259

Moina rectirostris, 32, 330

inegalospheric, 63

microgametocyte, 215, 223-

mole, 208, 209, 221, 231

meganuclei, conjugation of,

227, 248, 256-259

(see Talpa)

390

microhaemozoite, 256

Molge sp., 344 (see also

niegaii ucleus, 42, 372, 394

micromerozoites, 256

Triton)

Megascolex armatus, 328

micronucleus, 42, 376, 394

mollusca, sporozoan para-

Meigen, 54 (footnote)

micropyle, 227, 228

sites of, 205-207, 210,

melanin pigment, 242, 243,

microschizont, 256

338

252

microsphere, 63

Molybdis, 230, 238

melanipherus (Polychromo-

microspheric, 63

— entzi, 344

philus), 270, 351

microspora (Glugea), 341,

Monedula turrium, 349

Melasoma populi, 335

342

moniezi (Amoebidium), 329,

Meleagris gallopavo, 348

Microsporidia, 275, 296,

330

Melolontha brunnea, 335

308

monilis (Lankesterella),265,

— sp., 199, 335

Microsporidium, 297

267, 345

melolonthaebrunneae (Gre-

microsporozoites, 256

monnieri (Geneiorhynchus),

garina), 335

Microthoracina, 402

175, 200, 335

Melospiza fasciata, 348

Microthorax, 402

Monochilum, 402

— georgiana, 348

Miescheria, 301, 308

Monocystidea, 175, 176,

niembranellae, 370

miescheriana (Sarcocystis),

192

Menospora, 201

303, 306, 308, 351

Monocystis, 165, 166, 169,

— polyacantfia, 201, 332

Miescher's tube, 300

172, 173, 184, 193, 271,

Menosporidae, 190, 201

migration of parasitic germs,

273

meridional canal, 65

164, 207, 252, 290

— life-history, 154-164

Merkel, 121, 123

Mikrogromia, 79, 80, 140

— agilis, 154, 193, 328

merluccii (Myxobolus), 342

Miliolidea, 86, 139, 142

— aphroditae, 175

Merluccius merluccius, 342

Miliolina, 87 (footnote),

— clymenellae, 326

— mdgaris, 342

139

— enchytraei, 328

meront, 292

MUiolinidae, 86, 142

— foliacea, 326

merozoite, 166, 213, 222-

— trematophorae, 143

— lacryma, 329

224, 245

Milled, 114, 139

— legeri, 333

Mesnil, 168, 229, 231, 232,

Milvus migrans, 349

— leydigi, 326

235, 271

Minchinia, 233, 234

-- lumbrici, 327, 328

mesnili (Addea), 223, 224,

— chitonis, 227, 234, 236,

— magna, 327, 328

233, 337, 359

338

— mitis, 324, 327

— (Diplospora), 231, 345

— sp., 338

— mobttis, 329, 330

— (Haemogregarina), 346

minima (Anguillida), 265

— pachydrili, 328

— (Ophryocystis), 337

— (fMnkesterella), 265

— perichaetae, 328

mesnilii (Caryotropha),

Miniopterus schreibersii,

— pitosa, 327, 328

206, 217, 223, 225, 236,

270, 350

— porrecta, 327, 328

237, 327

minor (Diplocystis), 178,

— sp., 328, 339

Mesodinium, 399

194, 334

— stiedae, 232

Mesostomum ehrenbergi,

minuta (Goussia), 344

— thalassemae, 328

325

minutum (Coccidium), 208

monogenetic, 166

Mesozoa, 298, 315

Miogypsina, 147

monogony, 210

metabolism of host - cell,

mirabilis (Ceratospord),

mononts, 76, 210

208

194, 326

Monosporea, 230

Metacineta, 418, 424

— (Suncystis), 194, 335

Monosporoblastea, 229

Metacinetina, 424

mirandellae (Pleisiophora),

Monostomatidae, 140

Metchnikovdla, 316, 324

339

monozoic, 165

— spionis, 317

Mixi/nmusfossilis, 342

monura (Henneguya), 340

442

INDEX

Morica sp., 202, 335

myocyte-fibrillae, 156, 211, '

Myxosoma, 294, 295

morphology of Hetero-

254

- — ambiguum, 295

karyote body, 393

myoneme threads, 365

— dujardini, 294, 342

morula, 309

myophan threads, 365

Myxosporidia, 150, 153,

mosquito, 243, 248, 249

Myotis capaccinii, 351

165, 166-168, 208, 274-

Motacilla alba, 349

— myotis, 351

297, 302, 303, 305, 30G,

Motdla maculata, 342

Myriapoda, sporozoa of,

320

— sp., 287

206, 331

Myxosporidium congri, 340

— tricirrata, 233, 342

Myriapods. Ciliate parasites

Myxotheca, 48, 51, 52, 54,

motdlae (Goussia), 236,

of, 405 '

140

342

mystacidarum (Gregarina},

mouse, 221, 236 (see also

335

Nais lacustris, 275, 328

Mus)

Mystacides sp., 199, 335

Naja tripudians, 346

mouth of Ciliata, 366

Myxicola dinardensis, 316,

najae (Haemogregarina),

movements of gregarines,

327

346

180-182

Myxidiidae, 277, 293

Nassula, 397, 400

— of protoplasm in Fora-

Myxidium, 286, 288, 295

Nassulina, 400

minifera, 48

— danilewskyi, 275, 294,

nasuta (Haemogregarina),

Mrazek, 297, 298

346

240, 267, 328

mucosa (Sarcocystis), 351

— giganteum, 283, 343

Nathansohn, 44

mucronata (Asterophoi'a),

— histophilum, 342

Navicella, 161

200, 336

— incurvatum, 340, 343,

neapolitana (Cretya), 344

— (Schneideria), 176, 199,

344

Xebalia serrata, 330

333

— lieberkuhnii, 281, 282,

Necrobia ruficollis, 335

mucronatum (OMoro-

283, 291, 294, 297, 303,

Nemathelmiuthes, sporozoa

myxum), 342

342

of, 325

MttgU auratus, 342

— sphaericum, 340

Nematocysts, 275, 372

— capita, 342

Myxobolidae, 277, 288, 289,

nematode- theory of Gre-

— chelo, 342

292, 295, 299, 307

garines, 154

— sp., 294, 343

Myxobolus, 293, 295

Nematoides, 203

Miiller, 153, 412

— cycloides, 342

— fusiformis, 203, 329,

miilleri (Myxobolus), 288,

— cyprini, 276, 278, 290,

331

295, 296, 340, 342

296, 341

— (Siedleckia), 154, 315,

— (Serosporidittm), 330

— dipleurus, 342

316, 326, 327

— (TMohania), 285, 286,

— dispar, 296, 341, 342

JTematopoda, 417

292, 330

— ellipsoides, 279, 283,

Nematopsis, 318

multiform tests, 58, 135

287, 295, 296, 344

— sp., 338

multiple amitosis, 292

— exiguus, 339, 342

Nemec, 6

— plasmotomy, 292

— globosus, 341

Nemertes delineatus, 325

multiplicative reproduc-

— inaeqnalis, 296, 343,

Nemertini, sporozoa of, 194,

tion, 290, 292

344

325

Munier-Chalmas, 60, 86,

— lintoni, 341

nemertis ( Urospora), 325,

92, 111

— merluccii, 342

326

munieri (Gregarina), 181,

— miilleri, 288, 295, 296,

Nemobius sylvestris, 335

333, 337

340, 342

Neosporidia, 166, 274, 285,

murinus (Polychromo-

— obesus, 295, 339

299, 322, 323

philus), 270, 351

— oblongus, 341

Neozygitis aphidis, 335

muris (Klossulla), 236, 351

— oviformis, 207, 339, 341

Nepa cinerea, 194, 200,

— (Sarcocystis), 301, 304,

— pfei/eri, 276, 277, 283,

233, 234, 335

306, 307, 308, 351

296, 340, 344

nepae (Kimeria), 230, 335

Murray, J., 118, 119

— pirifannis, 296, 342,

Nephelis atomaria, 328

Muscicapa atricapilla, 349

344

Nephthys scolopendroides,

Mus decumanus, 318, 350

— sp., 275, 328, 340, 342

327

— musculus, 351

— sphaeralis, 340

Nereis beaucoudrayi, 202,

— rattus, 351

— textus, 343

203, 327

Mustela putorius, 351

— transovalis, 342

— mltrifera, 202, 327

— vulgar is, 351

— unicapsulatus, 296, 342

Nerim, 204, 327

Mustelus canis, 343

— zschokkei, 340

Neritina fluviatilis, 236,

— laevis, 343

Myxocystis ciliata, 297, 328

338

— sp., 286, 293

Myxoproteus, 294

Nerophis aequoreus, 343

myocyte, 180

— ambiguus, 295, 342

Neumayr, 115

INDEX

443

Neveu-Lemaire, 264, 265

occurrence of Coccidia,

Ophryocystis, 192

newt, 208, 270 (see also

205

— biitscMii, 187, 333

Triton)

— of Gregarines, 169

— caulleryi, 337

Nicaea nilsoni, 330

— of Haemosporidia, 240

— francisci, 332

nicaeae (Aggregata), 330

— of Myxosporidia, 274-

— gametes of, 188

nigra (Gymnospora), 337

276

— hagenmiilleri, 336

Niphargus subterraneus,

— of Sarcosporidia, 300

— mesnili, 337

330, 331

octopiana (Benedenia), 234,

— schneideri, 177, 333

nobilis (Pterocephalus), 175,

338

Ophryodendrina, 422

198

— (Klossid), 235, 236, 338

Ophryodendron, 420, 422

Nodosaria, 115, 137, 142,

— (Legeria), 338

Ophryoghna, 401, 402

144

— (Legerina), 338, 359

Ophryoscolecina, 409

Nodosariidae, 144

octopianum (Eucoccidium),

Ophryoscolex, 408, 409

Nodosinella, 142

235, 338

Ophthalmidium, 109, 110,

Nonioni'Mt, 126, 142, 146

Octopus wdgaris, 235, 236,

143

Nosema, 297

338, 359

Opisthodon, 400

Notodromas monacha, 312,

octospora ( TMlohania), 296,

Orbiculina, 95, 136, 143

331

331

Orbitoides, 147

Notomastus lineatus, 327

octozoic, 189

Orbitolites, 100, 135, 139,

Notropis megalops, 343

Ocypus okns, 200, 335

143

worn (Eimeria), 207, 223,

ohlmacheri (Leptotheca},

— complunata, 51, 53 (foot-

224, 229, 231

344, 345

note), 71, 73, 104, 112

— (Legerella), 229, 331

oligacanthiis (Hoplorhyn-

— life-history, 73, 74

Aitbecularia, 143

chus), 201, 333

— dMptee, 102, 111

Nubecularidae, 143

Oligochaeta, Ciliate para-

— marginalia, 100, 111

nuclei, 372

sites of, 403, 404, 405

— tenuissima, 57, 108.

nucleolus, 3, 14, 156

— sporozoan parasites of,

Orbulina, 117, 145

nucleus, 2, 3, 13, 45, 46

275, 298, 327, 328

Orchesella villosa, 336

— division of, 15

Oligoplastina, 229

Orchestia littorea, 331

— position of, 71

Oligosporogenea, 297

Oria armandi, 316, 327

— of Cydoclypeus, 132 ;

Oligotricha, 408

Oriohis galbitla, 349

Discorbina, 123 ; Globi-

Olocrates abbreviatus, 207,

— oriolvs, 349

gerina, 119 ; Gregar-

335

ornata (Barrmissia), 230,

ines, 182, 183 ; Orbito-

— gibbus, 317, 336

233, 234, 235

lites complanata, 112;

Ommatoplea sp., 325

— (Phialoides), 200, 335

Patellina, 123 ; Pene-

Omophts sp., 201, 336

Oryctes nasicornis, 180,

roplis, 111 ; Polystomella,

Oniscus, 221

336

66, 70 ; Polytrema, 121 ;

Onychodactylina, 401

Oscillaria malariae, 239

Rotalia, 120 ; Saccam-

Onychodactylus, 396, 401

Otaria californicn, 305,

mina, 83 ; Spiroplecta,

Onych-odromus, 411

351

113; Textularia, 113;

Onychophora, sporozoon

Orthodon, 400

Truncatulina, 125

of, 331

Orthoptera, Ciliate parasites

— host-cell, 208, 241

Oocephalus, 202

of, 417

Numenius phaeopus, 349

— hispanus, 202, 335

0<ws vtdgaris, 349

Nummuliten, 59, 127, 139,

oocyst, 204, 210, 219, 227,

ow£is (Stylorhynchus), 337

146

251, 272

ovato (^l^ea), 210, 213,

Nummiditidae, 146

ookinete, 251, 259

217, 222-224, 228, 230,

Nummiditidea, 126, 146

Opalina, 364, 401, 404

232, 332

Nussbaum, 385

— nuclei of, 378

— (Gregarina), 196, 334

Nuttall, 253

Opalinina, 404

miforme (Coccidium), 206,

Nyctobates pennsylvanica,

Opalinopsis, 401, 404

226, 227, 232, 350

335

Opatrum sabulosum, 336

ovifvrmis (Myxobolus), 207,

yyctotherus, 364, 405

Opercularia, 413, 416

339, 341

Operculina, 126, 127, 146

om's (Babesia), 351

obesus ^[yxobolits (?) ), 295,

ophioutes (Sphaerorhyn-

— (Piroplasma), 270,- 351

339

chus), 202, 332

owidea (Glngea), 286, 340,

oblongatus (Stylorhynchus),

Ophioidina, 196

342

333, 336

— bonelliae, 196, 328

Owen, Major, 120 (foot-

oblong us (Myxobolus), 341

— discocoelulis, 325

note), 138

obtusa (Pleistophora), 329,

— haeckeli, 331

ox, 269 (see also /?os)

330, 331

Ophrydium, 413, 416

Oxytriclut, 412

444

Oxytrichina, 411
Oxyuris ornata, 325

pachydrili (Monocystis),

328
Pachydrilus pagenstecheri,

328

— semifuscus, 328
Pachygrapsus mannoratus,

153, 331

Pachyrhina pratensis, 336
Padda oryzivora, 349
Pagellus centrodontus, 343
Palaemon aspersus, 331

— rectirostris, 331

— serratus, 331
Palaemonetes varians, 331
pallida (Ceratomyxa), 340
Pampluigiis, 336
Panchlora exoleta, 336
panchlorae (Gregarina),

336

Pandion ludiaetus, 349
pansporoblast, 283
Paracoccidium prevoti, 233,

344
paradoxa (Didymophyes),

180, 198, 334
Paradoxostoma sp., 331
paraglycogen, 182, 218
ParaisotricJui, 403
Parainoeba, 213
Paramoecina, 403
Paramoecium, 401, 403
parasiticum ( A moebidium ),

313, 314, 329, 330, 336
parasitism of Heterokary-

ota, 364
Parkeria, 142
Parnus sp., 184, 336
parthenogenesis, 44, 183,

188, 252

Parula pitiayumi, 349"
Parus caeruleus, 349

— cyaneus, 349

— major, 349

parva (Leptotheca), 343
paruMS (Botdlus), 329, 330
Pasithea rectirostris, 331
passalicornuti (Gregarina),

336

Passalus cornutus, 336
Passer domesticus, 349

— hispaniolensis, 349

— montamis, 349
Patella vulgata, 234, 338
Patdlina, 123, 125, 145
Paw cristatus, 349
Pavonina, 144"
pebrine, 275
peduncle, 369

pelagic Foraminifera, 138
Pelecypoda, parasites of,

403, 405, 414
pellicle, 365
Pdosina, 141
pellucida(Doliocystis), 282,

327
pelseneeri ( Hyaloklossin),

206, 236, 338
pendula (Selenidium), 204,

327

Peneroplididae, 93, 143
Peneroplis, 93, 111, 135,

139, 142, 143
penetration of blood-cor-
puscles, 245
Percafluviatilis, 343
perfomns (Coccidiuin), 350,

351

perfbrata, 54 (footnote)
perforation of megalo-

sphere in Peneroplididae,

95, 99, 102
Perichaeta, 205

— armata, 328

— novaezealandiae, 328
perichaetae (Monocystis},

328
Peridinium bipes, 324

— diver gens, 324
Periloculina, 143
Peripatus capensis, 331
Periplaneta americuna,

194, 336

— orientalis, 196, 336
periplanetae (Glugea), 336
Perispira, 399
Peritricha, 413
Peritromina, 411
Peritromus, 410, 411
perlata (Leptotheca), 293,

339

— (Spliaerospora), 293
perlatum (CMaromyxum),

293

pernicious fever, 241
Pernis apivorus, 349
PeropJwra annectens, 339
Petrobius maritimus, 197,

336

Petrogale penicillata, 351
Pfeiffer, 164, 205
Pfei/erella, 230, 238

— gigantea, 342

— princeps, 350

— sp., 338

pfeifferi (Coccidiiim), 331,
347, 350

— (Myxobolus), 276, 277,
283, 296, 340, 344

Pfei/eria, 230

Pfei/eria schv.bergi, 351
Pfitzner, 378
Phaenocystes, 275-277,28 1

286, 288, 291, 293
Phalacrocorax graculus

349

— cristatus, 349
Phalangidae, 199, 338
phalangii (Sciadophora)

199, 338

Phalangium cornutum,
199, 338

— crassum, 199, 338

— opt'Zio, 199, 338
Phallusia mannnillata, 339
phallusiae (Pleurozyga),

339

pharynx, 367
Phascolodon, 400
Phasianus colchicv.s, 349

— sp., 349
Phialis, 200
Phialoides, 200

— orwate, 200, 335
PMaster, 402
philica (Gregarina), 335
Philodinid sp., 326
Philodryas olfersii, 346
Phoenicodrilus taste, 328
Phoxinus funchdoides,

343

— Zoevis, 296, 343
Phreatothrix prage'fisis,

328

Phronima sedentaria, 195,
331

— sp., 331

phronimae (Callyntroch-

lamys), 195, 331
Phronimdla sp., 331
Phryganea grandis, 200,

336

— rhombica, 336
Phryganeidae, 336
Phryganid larvae, 175,

199
Phycis mediterranea, 343

— phycis, 343
Phyllodoce, 327
Phyllognathus, 336
phylogeny of Myxospo-

ridia, 298

— of Sporozoa, 321
Phymata crassipes, 336
physiology of digestion in

Ciliata, 380
caudata, 349

349

Picus minor, 349
Piend, 336
pigment of Ciliata, 366

INDEX

445

jii'/niCiitifera (Amoeba),

Platemys sp., 346

Polyarthra platyptera, 326

325

Platoum, 140

Polychaeta, sporozoa of,

pike, 294, 296 (see also

Platycleis grisea, 336

270, 326, 327

Esox)

Platycystis, 204

Polychromophilus, 265, 270

pileata (Acanthospora),

platydactyli (Haemogre-

— melanipherus, 270, 350,

201, 336

garina), 346

351

Pileocephalinae, 199

— (Sarcocystis), 300, 308,

— murinus, 270, 351

Pileocephalus, 199

346

Polycystida, 175

— bergi, 335

Plutydactylus mauritani-

polydesmi (Ampfwroides),

— chinensis, 199, 335

cus, 300, 346

199, 332

— heerii, 175, 199, 336

Platyhelminthes, sporozoa

polydesmivirginiensis (Gre-

pilosa, (Monocystis), 155,

of, 325

garina), 331

327-328

Platystoma fasciatum, 343

Polydesmus complanatus,

J'ilulina, 52, 83, 141

Pleistophora, 238, 297

199, 332

Pilulinidae, 141

— acerinae, 339

— sp., 233, 332

J'imelia sp. 202, 336 ! — coccoidea, 330

— virginiensis, 332

J'imelodus blochi, 296, 343

— colorata, 330

Polydora agassizi, 327

- da^las, 296, 343

— danilewskyi, 345, 346

— coeca, 327

— se&oe, 343

— helmintJiophthora, 325

— /ara, 327

Pinnotheres pisum, 188,

— heteroica, 347

polydorae (Doliocystis), 327

331

— holopedii, 330

Polygordius neapolitanus,

Piramutana blochi, 343

— mirandellae, 339

326

pirifonnis (Myxobolus),

— oWiwa, 329, 330, 331

Polymitus, 250, 259

296, 342, 344

— rosea, 329

Polymnia nebulosa, 206,

Piroplasma, 254, 255, 265,

— schmeili, 330

223, 236, 327

269, 309

— sp., 276, 285, 325, 329,

polymorpha(Acanthospora),

— bigeminum, 242, 262,

330, 331

335

269, 338, 350

— typicalis, 296, 297, 340,

— (Eirmocystis), 179, 197,

— c«wi's, 242, 270, 337,

341

335

350

— virgvla, 329, 330

— (Gregarina), 196, 337

— equi, 242, 270, 350

Pleurocoptes, 403

359

— ovis, 270, 351

Pleuronectes platessa, 343

— (Leptotheca), 343

Pisces, sporozoan parasites

Pleuronectidae, 275

Polymorphina, 116, 145

of, 339-344

Pleuronema, 401, 403

Polymorphinidae, 145

Piscicola geometra, 328

Pleuronemina, 403

Polyphemus sp., 331

Placopsilina, 142

Pleurostomella, 144

Polyphragma, 142

Plagiocampa, 402

Pleurotricha, 411

Polyplastina, 229

Plagiopogon, 399

Pleurotrichina, 411

Polyrhabdina, 204, 317

Plagiotoma, 405

Pleurozyga, 195

polyspermy, 227

Plagiotomina, 405

— clavdlinae, 339

Pdysporea, 293, 298, 233,

Planaria fusca, 325

— distapliae, 339

Polysporocystidae, 229, 230,

— form, 325

— phallusiae, 339

233

planar iae (Pleurozyga),

— planariae, 325

Polysporogenea, 297

325

Pluvialis apricarius, 349

Polystomatidae, 140

Planarians, parasites of,

Pockenkrankheit, 278

J'olystomella, 55, 62, 74,

404, 414

Podocyathus, 425

126, 146

Planispirina, 143

Podophrya, 418, 422

— structure, 62

Planorbulina, 146

Podophryiua, 422

— (life-history), 66

PlasmotUum, 239, 265,

Podura aquatica, 336

Polystomellidae, 146

267

— i-iWojsa, 336

Polytrema, 120, 135, 146

— immaculatum, 267

podurae (Gregarina), 336

Polytricha, 405

— yfcocAt, 267, 350

Poecilus cupreus, 336

Polyxenus lagurus, 332

— malariae, 243, 254, 267,

Pogonites, 201

Polyzoa, sporozoan para-

332, 351

polar capsule, 275, 284

sites of, 328

— praecox, 267

— filament, 284

polyzoic, 165

— rivaa;, 243-254, 267,

Pollard, 194

Pomatoceros triqueter, 327

332, 351

Pollicipes cornucopia, 203,

Popovici, 266

plasmotomy, 291, 292

331

porcellanous Foraminifera,

plastiuoid granules, 218

— polymerus, 331

54

plastogamy, 79, 125

[nili/i.icniitha (Menospora),

Porcellio, 221

Plate, 317

201, 332

Porella, 409

446

INDEX

Porospora, 196, 223 Psttotricha, 412

Raia sp., 279

— gigantea, 151, 181, 196,

Psilotrichina, 412

— undulata, 343

197, 330

psorosperm, 153, 205, 275

railleti (Coccidium), 232,

Po-rosporidae, 196

psorospermica (Henneguya),

345

porrecta (Monocystis), 155,

288, 296, 341, 343

" Rainey's corpuscle," 301

327, 328

Psorospennium cuniculi,

Ramulina, 145

Porter, 369, 417

232

Ramulinidae, 145

Porthesia chrysorrhoea, 336

— haeckeli, 329

.Sawa esculenta, 231, 233,

portuni (Zygocystis), 331

— lucernariae, 324

236, 265, 267, 293, 344,

portunidarum (Aggregata),

Pterocephcdus, 171, 172,

345

196, 329, 331

190, 198

— temporaria, 293, 345

Portunus arcuatus, 196,

— gametes of, 187

rawoc (Leptotheca), 293,

331

— nobilis, 175, 198

345

Potammithus sp., 336

Pterospora, 177, 193

ranarum (Coccidium}, 344

Potamochoerus larvatus,

— maldaneorum, 193, 194,

— (Dadylosoma), 270

351

326, 327

— (Drepanidivm), 154,

praecox (Plasniodium), 267

Pterotrachea sp., 169, 338

239, 255, 270

— (Stylocystis), 199, 337

pterotracheae (Gregarina),

— (Karyophagus), 270,

praemorsa (Aggregata),I53,

338

344

329

Ptychocylis, 409 — (Lankesterella), 239,

prevoti (Paracoccidium),

Ptychodera davigera, 339

255-257, 260, 261, 265,

233, 344

— sarniensis. 339

267, 270, 345

primary sporoblast, 159

Ptychostomum, 403

— (Laverania), 270, 345

primite, 178

pidclier (Trichorhynchus),

ram (Haemogregarina),

primitive disc, 106, 130

198, 332

346

— sphere, 283

Pullenia, 138, 145

— (Isospora), 232

princeps (Pfei/erdla), 350

Pulmnulina, 119, 138, 146

ray, 240

principal host, 253

puncti/era (Glugea), 341

reactions of paraglycogen,

pronucleus, 219, 259, 273

puteana (Zygocystis), 331

182

propagative reproduction,

Pygospio seticornis, 327

Redi, 153

291

Pyralis viridana, 336

reduction, 188, 225, 273,

proprium (Coccidium), 225-

Pyrosoma, 269

291

227, 272, 344

Pyrrhula europaea, 349

reduction-divisions, 26

Prorodon, 367, 396, 397,

— vulgaris, 349

reduvii (Hyalospara), 336

399

Pyrsonymplia, 369, 417,

Reduvius personatus, 336

Prorotriehina, 400

418

redwater, 242

Prostomial process, 367

Python retwulatus, 346

regeneration, 392

Proteosoma, 250, 257, 265,

pythonis (Haemogregarina),

— of Stentor, 392

267

346

relapse (malarial), 252

protomerite, 174

Pyxinia, 200

reliquat kystal, 159

protoplasm, 4

— crystcdligera, 334

— sporal, 161

— continuity of, 5

— frenzeli, 172, 333

Remak, 4, 14, 204

— of Foraminifera, 48

— mobiuszi, 332

renicola (Leptotheca), 293

Protozoa, sporozoan para-

— rubecida, 174, 189, 200,

343

sites of, 324

334

renis (Karyamoeba), 318,

provincialis (Stictospara),

pyxinin granules, 182, 218

345

199, 335, 336

Reophax, 142

Prowazek sp., 159, 161, 390,

quadratum (Chloromyxum),

repair of tests of Foramini-

407, 412

340, 343, 344

fera, 57

Psammoryctes barbatus,

quartan fever, 241

repdini (Acanthospwa),

298, 328

— parasite, 243-254

338

psu.mmoryctis (Hexactino-

Quinqiieloculina, 52, 87,

reproduction of Hetero-

myxon), 298, 328

111, 137, 139, 143

karyota, 381

Psammosphaera, 55, 141

— of Galcarina, 120 ; Cal-

" Pseudo-coccidies," 320

rabbit, 209, 232

cituba, 112 ; Cornuspira,

pseudo-cyst, 183, 187

Raia alba, 343

74, 111 ; Cristdlaria,

Pseudodijftiigia, 140

— asterias, 343

116 ; Discorbina, 123 ;

pseudonavicella, 153, 161

— batis, 343

Euglypho., 53, 79 ; Hali-

Pseudoplatystoma, 343

— davata, 343

physema, 84 ; Hyalopus,

pseudopodia, 48, 152, 177,

— mosaica, 267, 343

80 ; Mikroyromia, 80 ;

280

— pundata, 267, 343

Orbitolites, 73, 74, 105,

INDEX

447

111 ; Patellina, 123 ;

(footnote), 82, 95 (foot-

Sagenella, 141

Peneroplis, 111; Pvlysto-

note), 115, 119, 120

Sagitta claparedii sj)., 325

niclla, 67, 72 ; Quinque-

(footnote), 136

sagittae (Amoeba), 325

tin-iiliiia, 111 ; Rotalia,

RhyacophUa sp., 200, 336

sagittata (Ancora), 195,

1 20 ; Saccammina, 83 ;

Rhynceta, 370, 418, 422

326

Triclwspliaerium, 76, 82

Rhynchelmis obtusirostris,

Sagrina, 145

— of Foraminifera, sum-

328

salamander, 208, 270

mary of evidence, 77

Rhynchobolus americanus,

salamandrae (Coccidium),

of megalospheric form

327

345

of Cvrnuspira, 74, 111 ;

Rhynchocephala, 240

— (Karyophagus),27Q,B4i)

Cristellaria, 116 ; Jtis-

Rhynchonerella fulgens,

Salamandra maculata, 345

corbina, 123 ; Orbitolites

327

— salamandra, 345

foiiiplanata, 74, 112 ;

riedyi (Haemapium), 270,

Salpa aeruginosa, 339

0. duplex, 111 ; 0. mar-

344

— cunfoederata, 339

yiiuilis, 111 ; Pati'lliiiu,

rileyi (Sarcocystis), 347

— maxima, 339

123 ; Peneroplis, 111 ;

Rimulina, 144

• — vagina, 339

Polystomella, 72 ; Quin-

ring-form, 243, 246

sa/pae (Gregari)ia), 339

queloculina, 111

rivoltae (Diplospora), 231

Salvelinus fontinalis, 312,

— of microspheric form of

robustus (Dactylophorus),

343

Calcarina, 120 ; Orbito-

198, 331

Sapphirina sp., 331

lites complanata, 73,

Rompel, 363

sarcocy stiu, 301

105, 112 ; Polystomella,

rosace, 222, 243

Sarcocystis, 308

67 ; Ratal ia, 120

roscoviana (Hyaiospora),

— falcatula, 348

reptiles, 240, 254, 275

197, 336

— Awe^i, 305, 351

residuary nuclei, 283, 285

roscoviense (Coccidium),

— immitis, 351

— protoplasm, 220, 243,

347, 349, 350

!!in!i')/ianni, 351

250, 252, 253, 255

rosea (Pleistophora), 329

— miescheriana, 303, 306,

Restkorper, 159

rosette, 239, 240, 243,

308, 351

Reticularia, 47

247, 255

— mucosa, 351

reticularis (Ceraiomyxa),

Ross, 240, 253, 262

— mwm, 301, 304, 306,

344

Rossbach, 379

307, 308, 351

retral processes, 62

rostrata (Sphaerospora),

— platydactyli, 300, 308,

Reuss, 54 (footnote)

294, 343

346

Rliabdammina, 141

rostrum, 217

— rileyi, 347

RJiabdamminidae, 141

Rotalia, 120, 142, 146

— sp., 348, 349, 350

Rhabdogeniae, 168

Ratal idae, 145

— teweZ/o, 302, 304, 305,

Rhabdogonium, 144

Rotalidea, 120, 139, 145

308, 351

Rliabdospora, 238

Rotalina, 120

sarcode, 2

— thelohani, 339, 340,

Rotifera, sporozoa of, 325

SarcopJiaga carnaria, 836

341, 342, 343, 344

Ritbecula familiaris, 349

Sarcosporidia, 150, 165,

Rhabdostyla, 416

— (Pyxinia), 174, 189,

166, 167, 168, 275, 281,

Rhadinaea merremii, 346

200, 334

298, 299, 308, 322

Rhamdia sebae, 343

ruminants, Ciliate parasites

sarcosporidiosis, 300, 302

Rhafhidospora, 317

of, 400

sardinae (Coccidium), 340

— le danteci, 317, 336

Rupertia, 146

satellite, 178

liliiita sqiidtina, 343

Russow, 5

Sauropsida, 232

/'// iiinliiph its ferrum-equi-

Saxicola oenant/ie, 349

iiniii, 351

Sabella, 327

Scafthidiodon, 400

lili ij/i<rj)fialus annulattis,

sabellae (Sclenidium), 326,

scarabaeirelicti (Grega-

262, 338

327

rlaa), 337

Rhizammina, 55, 141

Sabellidae, 316

Scardbaeus relictus, 337

Rhizopoda, 47, 320, 321,

sabellidarum (Toxospori-

Scardinius erythrophthal~

322, 323

dium), 316, 326, 327

mus, 294, 343

Rhizotrogiis aestiwis, 197,

sabrazesi (Sphaeromyxa),

Scaurus trislis, 337

199, 336

341

Schacko, 111, 116, 119

— sp., 336

Si.i era iiuiiuia, 52, 54, 83,

Schaudinn, 40, 51, 69, 72,

Rhopalocephalus carcino-

139, 141

74 (footnote), 75, 76, 82,

matosus, 320

Saccamminidae, 141

111, 112, 123, 161, 16C,

Rhopalonia, 198

Sachs, 5

168, 205, 208, 209, 210,

— geophili, 198, 331, 332

saenuridis (Vrosp&ra], 194,

211, 221, 227, 231, 232,

Rhumhler, 50, 55, 58, 74

328

233, 234, 240, 243, 245,

448

INDEX

246, 248, 250, 252, 257,
259, 267, 291, 307
Schewiakoff, 79 (footnote),
181, 318-320, 367, 398,
399, 402, 403, 424
. Schizocystis, 188, 191, 316

— gregarinoides, 191, 333
schizogony, 166, 190, 204,

208, 209, 212, 213, 222,

223, 243-247, 255

— of Myxosporidia, 290-
292

Schizogregarinae, 176, 191
schizont, 166, 212, 222-

224, 243-247
schizontocyte, 223
schizura (Henneguya), 341,
Schleiden, 2
Schlumberger, 86, 90, 92,

111, 115, 117, 120, 121,

133

Schmeil, 318
schmeili (Pleistophora),

330
Schneider, 169, 205, 232,

317
schneideri (Barroussia),

233, 332

— (Cystobia), 324

— (Diplocystis), 194, 336

— (Eimeria), 230, 332

— (Lithocystis), 194, 195,
324

— (Ophryocystis), 177, 333
Schneidena, 199

— caudata, 199, 337

— mucronata, 176, 199,
333

— sp., 333

Schneiderian body, 360
Schuberg, 407
schubergi (Coccidium), 206,

210-221, 228, 332

— (Pfei/eria), 351
Schubert, 113
Schultze, M., 4, 50, 51, 55,

82, 123
Schulze, 71
Schioagerina, 146
Schwann, 2, 14
Schwartz, 13
Sciadophora, 199

— fissidens, 338

— goronowitschi, 338

— phalangii, 199, 338
Sciadophorinae, 199
•S'ciara nitidicollis, 199,

337
Scololepis fuliginosa, 204,

327
Scolopendra, 175, 198

Scolopendra cingulata, 332

— morsitans, 233, 332
scolopli (Haplospoi-idium),

311, 327
Scoloplos mutter i, 311, 315,

327
Scolopocryptops sexspinosus,

332

Scomber scombrus, 343
Scorpaena, 280, 293

— porcus, 343

— scrofa, 343

— sp., 343
Scutigera, 198

— forceps, 332

— sp., 332
Scyllium, 279

— canicula, 343

— catulus, 343

— stellare, 343
Scyphidia, 414
secoudary mass, 57
segmentation, 44
selection of materials of

test, 52

Selenidium, 176, 189, 203,
315, 316, 317

— annulatum, 327
— • cirrhatuli, 326

— echinatum, 203, 204,
326

— "en point et virgule,"
203

— " en virgule," 203

— eunicae, 326

— pendula, 204, 327

— sabellae, 326, 327

— serpulae, 327

— sp., 326, 327

— spionis, 324, 327
Semper, 111

Sepia officinal™, 228, 234,

235, 338, 359
Seps clialcides, 346
Septata, 175
septate, 173
Sericostoma, 199, 200, 201

— sp., 337

Serinus canarius, 349
Serosporidia, 150, 167, 312
Serosporidium , 312

— cypridis, 312, 329

— gammari, 330

— mVlleri, 330

— sp., 330

serpentium (Drepanidium),

256, 266, 345-347
Serpula contortuplicata,

327

serpulae (Selenidium), 327
Setophaga ruticilla, 319

sexual cells, 44

shell of Foram'nifera, 52

shell wall, structure, 56

Shephearddla, 82, 141

Sichelkeim, 161

Siebold, 153

Siedlecki, 161, 170, 172,

180, 200, 213
Siedleckia, 315

— nematoides, 154, 315,
316, 326, 327

Sigmoilina, 89, 143
siliceous tests of Foramini-

fera, 53
silkworm, 297

— disease, 275, 276, 290
Silpha laevigata, 337

— thoracica, 201, 337
Simocephalus vetulus, 330,

331

Simond, 270
simondi (Coccidium), 331,

332

— (Haemogregarind), 267.
344

simple plasmotomy, 292
simplex (Adelea), 233, 334

— (Chitonicium), 317, 338

— (Sphaerocystis), 197, 334
Simulium ornatmn, 337
sipunculi ( Urospora), 328
Sipunculus, 194

— nudus, 328

size of Heterokaryota, 364
Sminthurus sp., 337
Smith, 300, 306, 307

— and Kilborne, 262, 269
socius (Ghytridiopsis), 317,

324, 333
sole, 240, 267
Solea vulgar is, 344
Solen vagina,, 318, 338
Solenophrya, 425
Sollas, 53 (footnote)
sophiae (Anthorhynchus),

199, 338
soror (Gregarina), 336

— (Klossia), 236
Sorosphaera, 141
Sparotricha, 411

sparsa (Gonospora), 177,

326

Spatangus purpureus, 324
Spathidium, 397, 398
Spatula clypeata, 349
sperm-morula, 156
spermatic!, 186
Spermatobimn, 193
Spermatophagus, 193

— eclipidrili, 328
— freundi, 328

INDEX

449

spermatozoa, 250

spore-mother-cell, 251 stephani (Glugea), 341

spermatozoid, 186

spores of Coccidia, 227 Mephanophora, 200

sperm-mother-cell, 250

— of Mvxosporidia, 286-

— lucani, 200, 334

sphaeralis (Myxobolus), 340

289

Stephanopogon, 396, 399

Kjibii e r ic u m ( Myxidium ) ,

sporoblast, 159, 220, 251, Sterki, 362, 410

340

272, 284 Sticholonche, parasites of,

ftphaerocephalus, 202

sporocyst, 160, 189, 220,

423

Sphaerocystis, 190, 197

227, 272

Stichospira, 411

— simplex, 197, 334

Sporocystea, 229

Stichotricha, 411

Sjihaeroidina, 138, 145

sporocyte, 243

Stictofpora, 199

Sphaeromyxa, 294

sporoducts, 183

— proviiicialis, 199, 335,

— balbianii, 287, 340, 342 sporogony, 166, 204, 208,

336

— incurvata, 340

209, 215, 247-252,

Stictosporinae, 199

— sabrazesi, 341

261

stiedae (Eimeria), 232

Hphaerophrya, 418, 422

sporont, 157, 175, 285

— (Monocystis), 232

Sphaerorhynchus, 202

— of Thtlulwmia, 292

Stigmatogaster gracilis,l9&.

— ophioides, 202, 332

sporophore, 156

332

Spliaerospm-a, 286, 293,

sporoplasm, 160, 284, 288

Stiles, 231, 232

295, 298

sporozoa, general characters,

Stizostethium luciopercOj

— divergens, 279, 340

151, 164-168

344

— elegans, 293, 294, 341

— affinities and phylogeny,

Stold, 275, 298

— masovica, 294, 339

321

stomach, 251

— perlata, 293

sporozoite, 160, 220, 243,

Storthosphaera, 141

— rostrata, 294, 343

251, 272, 306

Strasburger, 4, 7, 9, 10

sphaerulosa (Ceratomyxa),

— of Coccidium, 210, 211

Strej)silas interpres, 349

286, 293, 341, 343

sporulating body, 243

stricta (Glugea), 336, 337

Sphingvnolus sp., 337

sporulation, 152, 242

Strix flammea, 349

Sphyraena sphymena, 344

Squcdius cephalus, 296,

Strombidium, 409

— vulgaris, 344

344

Strongylidium, 411

Spilotes pullatus, 346

Squamulina, 143

Stroiigylocentrotus lividus,

Spinax spinaz, 344

Squaiina angelus, 344

324

— vulgaris, 344

Stacheia, 142

strongylura (Henneguya),

Spio fuliginosus, 191, 327

Staphylinus olens, 337

344

— martinensis, 317, 327

Starcovici, 269

Sturnus vulgaris, 349

spionis (Gregarina), 317

Statira unicolor, 337

Stylobryon petiolatvm, 324

— (Melchnikovdla), 317

statirae (Gregarina), 337

Stylocmnetes, 419, 421

— (Selenidium), 324, 327

staurocephali ( Kollikerella),

Stylocystis, 199

spiral membranes, 370

196, 327

— praecox, 199, 337

— passage, 94

Staurocephalus rudolphii,

Stylonychia, 411, 412

Spirillinidae, 145

196, 327

Stylorhynchidae, 183, 190,

Spirobolus marginatus, 198,

Stegochilum, 402

201

332

Stein, 154, 406, 407, 408,

Stylvrhynchus, 161, 202,

Spirochona, 413, 414

421

271

— conjugation of, 387

Steinhaus, 208

— gametes o', 1 84

— nuclei of, 375, 376

steini (Gregarina), 337,

— caudatiis, 338

Spirochonina, 414

359

— longicollis, 175, 202,

Spiroloculina, 86, 142

stellifann is (A ctinocephft-

317, 324, 333

Spiroplecta, 58, 113, 114,

lus), 200, 333, 335, 336

— oblongatus, 333, 336

144

Stemm-pseudopodium, 281

— ovalis, 337

Spirostomum, 405

Stempell, 285, 291, 292

subimmaculata ( Ifaema-

spleen, 207, 208, 240, 242,

Stenocephalus, 198

moeba), 270

248, 255

Stenophora, 198

Succinea gigantea, 338

splendens ( Dactylosoma),

— juli, 198, 332

— pfei/eri, 338

270, 345

Stentor, 405, 406

— putris, 338

sporal residuum, 161, 220

— regeneration of, 392

suckers, 371

spore, 152, 220

— roeseli, 324

supplemental skeleton, 57

— cyst, 251

Stentorina, 406

suppuration, 163, 277, 289

— formation, 385

stepanovi (Haemogregar-

supra-oral lobe, 367

— formation in Myxo-

ina), 266, 267, 346

Sus dmnesticus, 351

sporidia, 282-285

stepanoviana (Haemogre-

swarm-spores, 72, 292

— membrane, 284

garina), 346

Sycia, 203

29

450

INDEX

Syria inopinata, 175, 203,

324, 326
Sylvia atricapilla, 349

— hortensis, 349
Symphyta, 154
Synactinomyxon, 298

— tubiftcis, 298, 328
synapsis, 28
Synapta, 194

— digitata, 324

— inhaerens, 324
synaptae ( Urospora), 190,

324
Synchaeta pectinata, 326

— tremula, 326

— sp., 326
Syncystis, 194

— mirabilis, 194, 335
Syncytium, 5
Syngnathus acus, 343
Synodontis schall, 344
Syringammina, 141
Syrnium cduco, 349
syzygy, 178, 248

Taenia, 276, 325
Talpa europaea, 351
Tangl, 5

Tanypussp., 199, 337
Tarentola mauritanica, 346
Technitella, 141
Te#i»a sp., 206, 236, 338
Telosporidia, 166, 168, 204,
285, 322, 323

— life-cycles of, 271
tenax (Gainocystis), 197,

334

— (Monocystis), 155
tench, 208, 279
Tenebrio molitor, 150, 337
Tenebrionidae, 317
tenella (Sarcocystis), 302,

304, 305, 308, 351
tenellum (Coccidium), 232
tentacle-like processes, in

Pterospora, 177
tentacles of Suctoria, 370
tennis (Beloides), 201, 334

— (Henneguya), 339
Terebella, 194
terebellae (Gonospora), 190,

194, 326, 327
Termes, Ciliate parasites of,

418

Termes flawpes, 337
terminology of malarial

parasites, 243
tennitis (Gregarina}, 337
tertian fever, 241

— parasite, 243-254, 259
test of Foraminifera, 52

testiculi (Legerella), 230,

331

testis, 207, 208, 230, 277
Testudo ibera, 266, 346
— marginata, 346
tetraspora (Gurleya), 297,

330

Tetrasporea, 232
Tetrasporocystidae, 229,

230, 232
tetrazoic, 165
Texas-fever, 242, 262, 269
Textidaria, 52, 113, 144
Textularidae, 144
Textularideoy 113, 139,

143

textus (Myxobolus), 343
Thalassema, 328
thalassemae (Monocystis),

328
Thanasimus formicarius,

337
Thelohan, 276, 283, 289,

294, 298, 299
tMlokani (Goussia), 342

342, 343, 344
Thelohania, 285, 297, 320

— contejeani, 276, 329

— giardi, 329

— macrocystis, 331

— miilleri, 285, 286, 292,
330

— octospora, 296, 331
Thurammina, 142
Thylakidium, 406
Thymallus thymallus, 344

— vulgaris, 296, 344
thysanurae (Glugea), 337

— (Gregarina), 336
Tiarina, 399

tick, 262

tick-fever, 242

Timarcha tenebricosa, 181,

337
Tinea fluviatilis, 344

— fo'wco, 296, 344

— wdgaris, 344
Tineola bisdiella, 207, 237
Tinoporidae, 146
Tinoporus, 146
Tintinnidium, 409
Tintinnoina, 409
Tintinnopsis, 409
Tintinnus, 409

Ti>«Za, 175, 179

— oleracea, 170, 337

— pratensis, 337

— sp., 337

tipulae (Actinocephalus),
337

(Adelea), 233, 337
Tukophrya, 418, 425
Torpedo marmorata, 344

— warce, 344

— torpedo, 344
Torquatella, 370, 409
tortoise, 275, 294
Tortrix viridana, 275, 295,

337
Totanus calidris, 350

— hypoleucus, 350

— totanus, 350
toxoides (Joyeuxella), 316,

327
Toxosporidium, 316

— sabellidarum, 316, 326,
327

Trachelina, 400
Trachelius, 366, 397, 400
Trachelocerca, 398
Trachelqphyllum, 398
Trachinus draco, 344
Trachurus trachurus, 344
transovalis (Myxobolus),

342

Trematode, 254, 276, 297
Triactinomyxon, 298

— ignotum, 298, 327
Trichorhynchus, 198

— pulcher, 198, 332
Trichocysts, 368, 371
Trichodina, 413, 414
Trichodinopsis, 414
TricJwgaster, 411
Trichonympha, 369, 417
Trichouymphidae, 417
Trichophrya, 420, 421
Trichorhynchus, 402
Trichosphaerium, 48, 76,

82

Trichospira, 402
Tricystida, 176
Tridactylus variegatns, 387
triformed tests, 58
trigemina (Eimeria), 331
Triloculina, 87, 89, 139,

143

Trinema, 141
Tringa alpina, 350

— sp., 350

Trionyx indicus, 270, 346

— sp., 346

— stellatus, 346
Trisporea, 238
tristeza, 242
Tritaxia, 144
Triton cristatus, 295

— sp., 225, 345
tritonis (Karyophagus), 270
Trochammina, 52, 142
Trochammininae, 142

INDEX

451

Trochilia, 401
Trochiis sp., 234, 338
trophic stage, 156
trophoplasm, 9
trophozoite, 156
tropical malaria, 241
Tropidonotus stolatus, 346
Trox perlatus, 337
ti-i'iK-ii.ta (Ceratvmyxa), 287,

340
r,-<>,/:-atulina, 124, 135,

146
truncation (Coccidium),

347
tmncatus (Disc&rfiynchits),

199, 337
tri(ttin'(Lymphosporidium\

312, 343
Tru.'-itlis sp., 337
Trygon, 280, 293

— pastinaca, 344

— vulgaris, 344
tuberculosis, 238
Tubifex rivulorum, 194,

298, 328

— tubifex, 328

tiibificis (Synactinomyxon),

298, 328
tumours, 278
Tunicata, sporozoan para-

sites of, 339
Turdus merit la, 350
Turtur auritus, 350

— turtur, 350
typicalis (Pleistophora),

297, 296, 340
typicus (Botellus), 312, 329,

330
Typton spongicola, 331

203

— dliptica, 283, 326
uncinata (Ancyrophora),

201, 333-335

— (Asterophora), 337
unicapsulatus (Myxobolus),

296, 342
uniform tests, 89
Upupa epops, 350
urinary bladder, 277
Urniila, 422
Urnulina, 422
Urocentrina, 403
Urocentrum, 403

Urodela, 240

Uroli'ptus, 411
Uronenw, 40'-'

•< 7'/<<, 412
Urosoma, 412
i'l-'iajiiim, 194

— nemertis, 325, 326

— saenuridis, 194, 328

— sipunculi, 328

— sp., 326

— x,/niij;,tii<\ 100, 324
Urostyla, 410, 411
Urotricha, 367, 398
Urozona, 402
Uvigerina, 145

vacuoles, 220, 246, 366

— contractile, 51, 152, 378

— food, 380
Vaginicolu, 413, 417

, 144

iiiia sp., 325
mlettei (Gregarina), 331

\'nfri/fiiiii, 144

Van Beneden, 4, 9, 26
Van Eecke, 305
r</,,,'.v,>w ii,-ttcii>; 337
en ii ill i,i>' (ahigea), 334
txirire (Gonospora), 326
variabilis (dfoussia), 340,

341, 342

varians (ffhigea), 337
variation in Foramiuifera,

133
/•'•ittrii'i'ta (Ki:hir

332

— (Kinnocystis), 179, 336.
337

vermir'ule, 251, 254, 258
Verneinli/ia, 114, 144
Vertebralina, 143
vertebrates, 205, 206, 207,

232, 253, 275, 295
Verworn, 58
Tes/>a media, 337
VespertUio rnurinus, 270,

351
vesperuginis (A chromati-

cus), 270, 351
Vesperugo sp., 270, 351
vestibule, 367
Virchow, 4
virgtda (Pleistophora), 329,

330

' v,,v<y<V/«), 351
vitreous Foraminifera, 54
wuoa; (lJln*iitiHiiii»(), 243-

254, 267, 351
roZtwa; globatvr, 324
Vorticella, 413, 414

— conjugation of, 387,
391

Vorticellina, 414
Vuillemin, 300

Wandolleck, 269
Wasielewski, 164,170, 173,

301, 305, 306, 307
ireWt««, 142
Wolters, 161
wood-louse, 221
Wright, 249, 416

Xenodon neuviedii, 347

yellow bodies, 276
yellowish - brown bodies,
253

Zacharias, 13, 309
Zalophus californ ianus,
351

'•s gemonensis, 347

— (Haemogreyariiitt), 347

— ]til>l>nerepist 347

— rii-ii/irfin-ns, 347
Zeller, 403, 404
zoid, i>51
zoidophore. 251
zoospore, 313
zoosjiores of Hyalopus, 82

— of Polystomella, 72

— of Trichosphaeriu m , 76
Zodtkamnium, 416
zooxanthellae in Foramini-
fera, 51, 118 (footnote)

zschokkei (Myxobohts), 340
Zygaenafilipendulae, 337
Zygocystis, 193

— coinefa, 193, 328

— partuni, 331

— puteaiift, 331
zygosis, 272
Zn<i"!i<>ma, 193

— gibbosum, 193, 328
zygote, 156, 159, 219, 227

250, 258, 272

Printed by R. & R. CLARK, LIMITED, Edinburgh.