BIOLOGY
LIBRARY
6
PROTISTS AND DISEASE
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PROTISTS AND DISEASE
VEGETABLE PROTISTS; ALGAE AND FUNGI, INCLUDING
CHYTRIDIINEAE ; VARIOUS PLASSOMYXINEAE, THE CAUSES
OF MOLLUSCUM CONTAGIOSUM, SMALLPOX, SYPHILIS,
CANCER, AND HYDROPHOBIA; TOGETHER WITH THE
MYCETOZOA AND ALLIED GROUPS
Being the Sixth Book published
for the Author on the same Subject
BY
J. JACKSON CLARKE, M.B. LOND., F.R.C.S.
SENIOR SURGEON TO THE HAMPSTEAD AND NORTH-WEST LONDON HOSPITAL,
AND SURGEON TO THE ROYAL NATIONAL ORTHOPAEDIC HOSPITAL
LONDON
BAILLIERE, TINDALL AND COX
8, HENRIETTA STREET COVENT GARDEN
1922
(.All tights resetted)
C15
BIOLOGY
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FEINTED IN GREAT BRITAIN
EEKATA.
On p. vi. of Preface in line 5 "nucleus " should be "cell."
On p. 109 mention should have been made that in 1892
Ivanovsky demonstrated the filtrability of mosaic disease in the
tobacco plant.
PREFACE
A CHANGE of title from "Protozoa and Disease" of four
preceding books to "Protists and Disease" has become
necessary by reason of my having found that the pathogenic
organisms dealt with are not protozoa, but protists allied to
Synchytriaceae. In other words, in making comparative
study of alien bodies that abound in the lesions of molluscum
contagiosum, cancer, and other diseases, we have examined
protozoa with great care when we should have given the
closest attention to every detail of the life-history of certain
vegetable protists, especially Synchytriaceae and some
Olpidiaceae.
But in spite of our having searched in the wrong depart-
ment of biology the nature of 'cancer, smallpox, and other
human diseases would before now have become plain to
all, had there not been some weakness in the foundations
of biology. The nature of this weakness is not obscure:
it consists in a serious defect in the cell- theory, a defect
the bearing of which is shown in chapters of this book, and
which may also be briefly outlined here.
If we bear in mind that the word "nucleus" denotes
a morphological conception, the cell- theory in its present
v a 2
582150
vi PREFACE
accepted form may be defined as consisting of Virchow's
" Omnis cellula a cellula" (1855) -plus Flemming's " Omnis
nucleus a nucleo " (1882).
The original theory comprised two propositions; firstly,
that the nucleus is the unit of structure and function in
both plants and animals; and, secondly, that new nuclei
and new cells arise in an amorphous basis. The first part
was at once recognized by Virchow as a great advance in
science, but he did not attach importance to the second
part, which indeed was later found to be untrue for the
forms of life to which it was applied. In its present state
as defined above the theory has proved to apply to nearly
all known living things, and it has been the instrument by
which so much imperishable biology has been built up that
the fact that it is contradictory of dominant phases of
well-known groups of organisms has not yet received due
attention.
It applies as far as is known to all Metazoa, and to all
plants above the Thallophyta, and to most of these, and to
many Protozoa ; but it is patently at fault when it is applied
to dominant phases of certain protists, some thallophytic
and others protozoan.
That no qualifying clause has been added to the cell-
theory to meet this position is strange seeing that game-
togenetic chromidia are now commonplaces in biology, and
that these vital processes translate terms such as "free
nucleus-formation' 5 into prophecies fulfilled.
PEEFACE vii
In Nature variation is so great that misstatements
concerning reproductive processes of some forms of life
have proved to be accurately descriptive of what occurs in
other forms.
Denial of the existence of non-nucleated phases of some
protists renders complete comprehension of many diseases
impossible. In the following pages I show once again how
the plasson state plays a leading part in the lives of the
parasites which cause molluscum contagiosum, cancer,
smallpox, &c.
Had English pathology been conversant with Synchytrium
from the year 1892 to the year 1895, the immediate causes
of cancer, smallpox, and syphilis might have been agreed
upon during that period, and, incidentally a new province
of biology would have been then acquired.
The first practical aim of this book is once more to beg
those who in this country direct investigations into the
immediate causation of disease to arrange for systematic
examination of molluscum contagiosum. This minor malady,
which shows in the skin like dimpled pearls, deserves more
consideration than all the pearls in the world for the light
it sheds on other far more serious diseases. If unprejudiced
and willing examination of molluscum bodies is made in the
simple way described in this book, it will be recognised in
the course of a few days that these bodies are parasitic
organisms. In molluscum we have an easy key to smallpox,
the filtrable organisms, and to cancer.
viii PREFACE
Another aim has been to establish the biological relation-
ships of the pathogenic organisms dealt with; and I trust
that readers who are trained in the biology of cryptogams
will condone the verbal and ideal stumblings of a beginner ;
and that others, to whom the matter of this part of the book
may be as new as it was to the author two years ago, will
follow with sympathy and some profit the progressive, if
limited, illumination that has been attained.
In order to make this attempt possible, it has been
necessary for me to consult literature outside that contained
in our professional libraries, and I am under particular
obligation to the officers of the library of the Linnaean
Society of London, and of the Cryptogamic Botany Depart-
ment of the British Museum. Both for direct information
and for guidance in the choice of literature Mr. J. Rams-
bottom's articles in the " Transactions of the British
Mycological Society " have been indispensable to me.
My indebtedness to colleagues and others who have
assisted me with gifts of material and specimens is acknow-
ledged in the text, but I must make additional reference
to the skilled help generously given me by Dr. J. Herbert
Perkins, pathologist to the Hampstead and North-West
London Hospital.
J. JACKSON CLARKE.
LONDON, September, 1922.
CONTENTS
PAGE
PREFACE v
CHAPTER I.
FOUNDATIONS. Meaning of the term protist The cell-theory Chroniidia
Plasson Filtrable viruses Protoplasmic motion Culture of metazoan
cells and tissues Chromatin and nuclei Intra vital staining Medicine a
branch of biology Taxonomy Terminology Nomenclature
CHAPTER II.
SOME ALGAL AND FUNGAL PROTISTS. Algae Ulothrix zonata Vaucheria
sessilis Cystococcus humicola Bhodochytrium spilanthidis Fungi
Saprolengia Besting conidia Biologic forms of fungi Parasites of
Saprolegnia Peronosporeae Pythium Parasites of Pythium Pythium
debaryanum Nuclear processes in Pythium Phytophthora infestans
Cystopus candidus Details of structure in oospores Nuclear processes of
Cystopus Equivalence of a gerni-hypha to a brood of zoospores Zygo-
mycetes Gemmae Parasitic mucors Nuclei of Mucor Some features of
parasitic fungi Symbiosis Mitochondria 22
CHAPTEE III.
CHYTRIDIINEAE. The genus Chytridium Bhizidiaceae Polyphagus englenae
Cladochytriaceae Olpidiaceae Plasmodium-formation Sorus-formation
Course of the disease Olpidiopsis Nuclear processes in Olpidiopsis
Sphaerita endogena Synchytriaceae The life-cycle of synchytrians
Synchytriurn stellariae ibid, succisae ibid, endobioticum . ... 54
ix
x CONTENTS
CHAPTER IV.
PAGE
THE SYNCHYTRIAN NUCLEUS. Nuclear divisions in the sorus Sorus formation
in S. endobioticum The gametic stages in S. endobioticum A species of
Synchytrium in a thistle The nuclear cavity The synchytrian nucleolus
Plasson ; pycnoplasson, chasmatoplasson . . . . >, . . .78
CHAPTER V.
CANCER-BODIES" IN SYNCHYTRIUM AND IN SYPHILIS. Bird's-eye nuclei in
Synchytrium ibid, in cancer Living bird's-eye bodies in a syphilitic
lesion " Cells of endogenous origin " . . . . . , . 91
CHAPTER VI.
PLASSOMYXINEAE AND MOLLUSCUM CONTAGIOSUM. Definition of name Plasso-
myxineae Plassomyxa contagiosa, cultures Water cultures Enumeration
and details of vital changes in Plassomyxa contagiosa Not a Coccidium
Microhenads Kinds of filter used for virus filtration Historical notes
of virus filtration The size of microhenads The molluscum body not a
symbiotic cell Anaerobic cultures The histology of the tumour Further
cultural results Reaction to iodine and sulphuric acid Incubation
period of filtered virus The identity of Plassomyxa with the filtered
virus Synchytrium and Plassomyxa contagiosa compared The geo-
graphical distribution of molluscum Avian molluscum or bird-pox
Flagellate- diphtheria in pigeons Details of culture method . . .99
CHAPTER VII.
PLASMODIOPHORACEAE. Subdivisions of the group Plasmodiophora brassicae
Sorosphaera veronicae Spongospora scabies . . . . . . 128
CHAPTER VIII.
MYCETOZOA. Broad features of Didymium and Stemonitis-The plasmodium
Granules Protoplasmic motion The sclerotium Nuclear processes in
Mycetozoa Fertilization Chromidial elements Bionomics A parasitic
Mycetozoon Culture of a Mycetozoon Sporangia Morphological details 131
CONTENTS xi
CHAPTER IX.
PAGE
ACEASIBAE, AFFINITIES AND PHYLOGENY OF MYCETOZOA 155
CHAPTER X.
NOTES ON SMALLPOX, SYPHILIS, CANCER, ETC. Cystic ureteritis Olpidiiforma
cobboldi A false analogy Smallpox Guarnieri's Experiment Mitoses
in epithelial cells Variations in the parasites Cytoryctes, the cause of
vaccinia Spirochaetes in vaccinia Intranuclear phases of Cytoryctes
Nucleophaga and Karyorcyctes Parasitic forms occurring in Syphilis The
parasite of syphilis and Synchytrium Spirochaetes Gummata Syphilis
and cancer Cytoryctes luis Sarcoma and cancer Cancer in pathology
Connective-tissue cancer Parasites that contain chromatin Spirochaetes
in cancer Subdivision of the parasites A choriocarcinoma and some
parasitic nuclei Conclusions and comparisons Epithelial cancer Spor-
angium-formation in cancer Alternative modes of reproduction of cancer
parasites Spirochaetes in cancer Culture of cancer-parasites Plassomyxa
f orma-maligna ] mitation cancer Metastasis Conclusions Adenoma of
the breast Hydrophobia Pasteur Nucleoli Vaccines and pro-vaccines
Specific remedies for specific fevers ? Virchow Tumours in present-day
pa,thology 164
CHAPTER XI.
CHROMIDIA AND NUCLEI OF A PROTOZOON. Arcella Vulgaris, Life-history of
ibid., Cytology of The cell-theory adjusted to facts 212
LIST OF ABBREVIATIONS, ETC 220
BIBLIOGRAPHY 222
INDEX . . ' . 227
PROTISTS AND DISEASE
CHAPTER I
FOUNDATIONS
CIVILISATION still expects accredited instruction upon the
real nature of cancer and other tumours ; smallpox and
other fevers.
If these capital diseases were but fugitive discomforts,
it would still be of interest, even of importance, to inquire
into their causes for the purpose of adding to existing
biological knowledge.
These facts demand that we review the rudiments of
our biological information, and that we convert as much of
it as circumstances require or allow into knowledge by
personal practical work.
Protists. We need to know some very primitive forms
of life, some of those that are conveniently grouped in our
minds under the designation of protists. This name is not
now used in its original sense as invented by Haeckel,
synonymous with " Monera," to apply to a proposed new
kingdom consisting of organisms devoid of nuclei ; but as
one designation for the two overlapping sub-kingdoms or
1
2 \ ^ t&OTISTS AND DISEASE
phyla, the Protozoa and the Thallophyta, the latter term
applying to the algae and fungi, including the diatoms, the
desmids, and the bacteria. With Haeckel the Third King-
dom was to be that of the Monera, and any non-nucleated
cell was to be termed a cytode.
The question of the Monera was touched upon in 1877
by Huxley, but at that date the chromidial state of living
organisms was unknown and the data for even a partial
solution of the problem were wanting.
In 1896 the position was summed up judicioiisly by Delage
and Herouard : " For a long time great importance was
attached to the cytodes and the Monera of Haeckel . . . but
it has been found that this supposed absence of a nucleus
is explained in many cases by defective methods. Since
nuclei have been discovered in the most of the Monera, of
the cytodes, and even in bacteria, some people, by rather
hasty induction it seems to us, have denied the existence
of non-nucleated organisms." Remembering that filtrable
organisms, chromidia, and akaryote phases of protists such
as Sorosphaera (see Chapter VII) were unknown when the
passage just quoted was written, we cannot but admire the
moderation of thought and expression shown by the French
zoologists.
The Cell-Theory. A study of protists must include an
examination of the cell-theory of life as it exists at present
in biology. The nucleus was recognised as a normal feature
in the epidermal cells of orchids by Robert Brown in 1833.
FOUNDATIONS 3
In 1839 Schwann's view was stated thus : " The Cytoblas-
tema, or amorphous substance in which new cells are to be
formed, is found either contained within cells already existing,
or else between them in the form of intercellular substance.
... In cartilage it is very consistent and ranks among the
most solid parts of the body ; in areolar tissue it is gelati-
nous ; in blood quite fluid. ... In plants, according to
Schleiden, the nucleolus is first formed, and the nucleus
around it : The same appears to be the case in animals."
In 1841 Kemak described direct division of nuclei, and
in 1873 Anton Schneider described indirect division (karyo-
kinesis or mitosis). Coming to a more recent date I will
refer, and I do so with affection and gratitude, to Edmund
B. Wilson's " The Cell in Development and Inheritance,"
2nd edit., 1904. It is to be remembered that when Wilson
wrote generative chromidia had not been discovered.
This premised, one passage may be quoted, p. 294 :
" It may now be taken as a well-established fact that the
nucleus is never formed de novo, but always arises by the
division of a pre-existing nucleus."
Now, many chromidia, such, for instance, as some of those
of the protozoon Mastigella vitrea, arise for the very purpose
of making nuclei de novo, which is the same thing as free
nucleus -formation.
Disagreement between facts such as this and the generali-
sation just quoted are considered in Part III, 1912. Some
points call for restatement. Let us glance again at pictured
PROTISTS AND DISEASE
examples of two modes of origin of new nuclei, and we
see a great contrast. In Fig. 1 are seen three stages of
regular mitosis in a protist : chromosomes, centrosomes,
spindle, etc. In Fig. 2 new nuclei are being formed from a
chromidium, a segregated mass of akaryote germ-plasm that
has been extruded from the nucleus of its parent protist
FIG. 1. STAGES OF MITOSIS IN ACANTHOCYSTIS ACULEATA, A HELIOZOON :
a, metaphase ; b and c, anaphases. (From Doflein, after Schaudinn.)
From Part III.
and lies in the cytoplasm, equivalent to a metazoan ovotestis.
In the vegetative part of its life Mastigella undergoes mitosis
quite like that of Acanthocystis, Fig. 1.
Chromidia. An akaryote structure destined to produce
gametes illustrates one kind of chromidium, the generative ;
the other kind is the vegetative. Generative chromidia have
been recognised (H. Wager) as of two kinds ; firstly, those
that replace nuclei, and secondly, those that are capable of
being re-formed into nuclei. Of the latter the garnet o-
genetic chromidium of Mastigella is an example ; in this
FOUNDATIONS 5
case the origins of the new cells, Fig. 2, 2, Chr., are not
differentiated into nucleus and cytoplasm.
Vegetative chromidia are again of two kinds ; firstly,
portions of a nucleus extruded diffusely into the cytoplasm,
and secondly, chromatin accumulated in nucleus-like
structures.
FIG. 2. MASTIGELLA VITREA : 1. Formation of the chromidium (Chr.).
2. The chromidium increased in size. 3. The chromidium alone more
highly magnified, to show free nucleus -formation. N, nucleus.
G, gamete. (After Goldschmidt, from Doflein.) From Part III.
Once it is fully developed the chromidium, Fig. 2, Chr.,
is an independent organism much as is the prothallus of a
fern. If we could suitably subdivide it, each segment would
doubtless live and be able to produce gametes.
The foundation of all biology and pathology, the cell-
theory, as it exists to-day, is unsound in that it is contra-
dictory of akaryote states which are dominant in the lives
of certain protists.
Plasson. If we look at Goldschmidt' s drawing, Fig. 2, 2,
of the origins, or primordia, of the gametes of Mastigella,
6 PROTISTS AND DISEASE
when first they appear in the matrix of the chromidium,
we can see in them no differentiation of structure ; each
gametoblast is a particle of apparently structureless
material. For such substance Haeckel used the term
" plasson." This totipotential form of living matter has
been defined in an article on the Proteomyxa by S. J.
Hickson :
" It seems probable then that the protoplasm of the
Proteomyxa really represents the protoplasm of the higher
Protozoa and Metazoa plus the substance of the nuclei.
It is the substance which van Beneden, in 1871, proposed
to call the ' plasson,' that is, the formative substance which
is capable of becoming, either in ontogenetic course or in
phylogenetic course, monocellular elements, after that the
chemical elements of the plasson have been separated to
constitute a nucleus and a protoplasmic body. ''
Haeckel was right in that non-nucleated organisms
exist, but those we know have also phases in which they
have nuclei ; therefore he was mistaken in assuming that
his cytodes were of necessity devoid of nuclei at all stages
of their life-history ; indeed, many of them have been found
to have nuclei at all stages.
In estimating Haeckel' s work we should remember that
he was the first to note the inception of foreign particles by
leucocytes ; the bearing of this function on immunity was
first indicated by Carl Roser in 1881, and later named
phagocytosis by Metchnikoff.
FOUNDATIONS 7
Filtrable Viruses. The living virus of foot-and-mouth
disease was found by Loeffler and Frosch (1898) to pass
through filters which arrest any known bacteria. Since that
date a number of other living poisons have been found
to be filtrable, including those of measles, smallpox, and
molluscum contagiosum.
Many pathologists now write with facility of " invisible
micro-organisms," so it is of value to examine this very
important field. M. Arthus, in a most interesting book
published last year, writes thus : " We admit that the
causal microbe exists, but suppose that it is so small that
it eludes microscopic search, and this hypothesis for it is
nothing more than a hypothesis is supported by the facts
elicited in the study of pleuro-pneumonia of cattle." The
author goes on to say that in the serous exudation of this
disease fine granules can be seen with the highest powers of
the microscope ; they can be stained, though with difficulty,
and they can also be cultivated on very special media.
Arthus asks whether we may not see in the virus in question
a link between the visible and cultivable organisms on the
one hand, and the invisible organisms on the other
hand.
We find no word here of these most minute of known
living units having any phases other than the filtrable.
And this is the usual view, though it is proved to be an error
by what is seen in simple water cultures of molluscum
bodies : see Chapter VI.
8 PROTISTS AND DISEASE
It is as if a new " Third Kingdom " were being erected
to replace that of the Monera. Just as there are cytodic
(plasson, chromidial) stages of some protists which have
obvious nuclei at other stages, so there are filtrable stages of
parasites such as molluscum corpuscles, which are relatively
large bodies; and, just as some living organisms may con-
ceivably be persistently akaryote, so others may possibly
exist only in the filtrable phase.
Protoplasmic Motion. " The colloidal nature of proto-
plasm is manifested in many of its properties. Its power of
adsorption which lies at the basis of many cell reactions and
certain staining processes, is similar to that of other colloids.
. . . The permeability of a vacuolate cell is in general the
resultant of the permeabilities of the ectoplast, cytoplasm,
and tonoplast" (L. W. Sharp, 1921). The chief cause of
stability in colloids is Brownian movement (Bayliss, 1920,
q.v.). This movement is seen in many living cells, e.g. in
the protoplasmic strands of Spirogyra. Streaming is probably
present in the protoplasm of all active cells. It was first
recorded in Chara by Corti in 1774. In some cases, as in
the cells of the stamina! hairs of Trad-escantia, the stream
does not carry the nucleus with it ; in other cases, as in the
leaves of Vallisneria, the nucleus moves with the rest of the
protoplast.
Most impressive are the to-and-fro currents of the
plasmodium of Mycetozoa : in these the outward current
lasts over a minute, the return a little under a minute. In
FOUNDATIONS 9
Fig. 38 is copied de Bary's instance of a rotatory movement
replacing the alternate currents in a mycetozoan plasmodium.
In a subsequent chapter an account is given of a streaming
or circulation of protoplasm in the bodies peculiar to the
disease molluscum contagiosum.
This streaming may last for several days and may be
accompanied by the presence of bud-like protrusions and of
separate minute spheres with a similar streaming. Apart
from other evidences in molluscum bodies this streaming is
a strong witness to life : and it is a phenomenon any one
who may have the material can reproduce.
Besides such movements of protoplasm of a cell there
are currents in channels or linear vacuoles : watching a
large fungus hypha growing in a slide-and-cover culture I
have seen in minute parallel channels steady currents pass
some in the direction of growth, others the opposite way ;
one such hypha was undivided when first seen, later septa
were formed, but these did not appear to affect the circula-
tion.
By fixing root-tips in a mixture of neutral formalin
(10 c.c.), K 2 Cr0 4 (2-5 g.), HgCl 2 (5 g.), H 2 (90 c.c.), Bensley
demonstrated the channels he named canaliculi, the presence
of which is an indication that intracellular circulation of
liquids exists. In mitosis the centrosomes and the two
spindle poles have been found to be alike electrically, and,
if so, they cannot represent an ordinary electromagnetic
field. The filament that connects a nucleus and the
10 PROTISTS AND DISEASE
blepharoplast at the base of many flagella suggests that the
movement of these is effected by the same apparatus as
mitosis. As is shown in Fig. 22, 6, zoospores of synchytrians
penetrate their host by a nuclear structure which resembles
a blepharoplast with its connecting filament ; other ehytri-
dians and, as Waterhouse found, the sporidia of Puccinia
graminis, appear to effect penetration in a similar
way.
Simulation of Life. In his book, " The Protozoa," 1901,
Calkins gave a good account of the life- simulating states of
dead matter : amoaboid movements simulated by a drop
of olive oil in water ; Buetschli's mock-protoplasm, olive
011 mixed with salt or sugar in water ; Rhumbler's shellac-
coated spicule of glass incepted by a drop of chloroform in
water and ejected when the shellac is absorbed, with many
other instances.
I have made Buetschli's experiment both with salt and
oil, and sugar and oil. A few crystals that project from
the oil into the water are seen to dissolve, causing active
currents of very brief duration ; and slow local passive
currents are seen in both oil and water ; there was nothing
that should be mistaken for active living matter.
Culture of Metazoan Cells and Tissues. Every cell of
a living metazoon is an animalcule, and with minute care
to exclude bacteria (see Lee's " Microtomist's Vade Mecum,"
1921) such cells may be kept alive and cultivated artificially.
Nerve-cells from the embryo frog were first grown by Ross
FOUNDATIONS 11
Harrison in 1907, the medium being lymph from adult
frogs. Next Burrows grew tissues from embryo chicks on
blood plasma in plate cultures. Using the same method
Carrel and Burrows cultivated tissues (kidney, spleen, bone-
marrow, etc.) of adult cats and dogs.
Connective-tissue from the embryo chick has been kept
in culture for as long as eight years by Ebeling. An incuba-
tion of three days was observed by Busse before the cells
of fragments of rabbit's heart or aorta developed new cells.
The latter are branched and anastomose, but when bacteria
are placed near them they become detached from one
another and round ; they are attracted to the bacteria
(chemiotaxis) (see the Lancet, April 29, 1922, p. 856). All
these features are in keeping with what is familiar in the
study of granulation-tissue by other methods. When the
infecting organisms of molluscum contagiosum and kindred
affections are more generally appreciated, such cell-cultures
in practised hands may be useful in the study of some
details of the stages of infection.
Cellulose and Chitin. Chemically isomeric with starch,
cellulose is one of the most abundant of the products of life.
Like starch it grows by intussusseption, and from it are made
a number of degradation products such as the jelly so freely
produced by many algae, etc. In the form of cotton- wool
it responds readily to the usual tests, turning blue with
iodine solution followed by sulphuric acid diluted with
water ; equal parts (Bower) or one of iodine solution to two of
12 PROTISTS AND DISEASE
acid (Chamberlain), also with chloro-iodide of zinc and iodine ;
and dissolving in saturated solution of copper hydrate.
Where fungi are present one might expect these reagents
would reveal them by colouring their cellulose, but the re-
actions are of value only when positive. It is rare to find
fungi that respond. Fungal cellulose often requires long
maceration in 15 per cent, potash solution before it may
react. In Mycetozoa de Bary obtained the reaction but
once in the innermost layer of the sporangium wall of
Trichia varia, and had many negative results. The capillitia
of Didymium and Stemonitis changed to violet with the
acid alone.
Woody fibre is composed chiefly of lignin, a modification
of cellulose, but does not react in the same way. In pro-
tozoa, chitin, a nitrogenous substance akin to keratin, takes
the place of cellulose, though one Rhizopod, Chlamydomyxa,
is partially enclosed in a capsule of cellulose. Cellulose also
forms the tunic of Ascidians, animals near the vertebrates
in organisation.
Chromatin and Nuclei. The living nucleus can be
studied easily in many protists and cells. It contains
refracting material which stains readily ; hence called
chromatin (Flemming, 1879). When this is not diffused
through the whole nucleus we see in fixed preparations that
it lies in a net which is continuous as a rule with the cyto-
plasm through the nuclear membrane. This supporting
net is called linin, doublet of linen (Schwarz, 1887).
FOUNDATIONS 13
In mitosis spindles are formed by re-arrangement of
linin fibres. Spindles are usually formed inside, but some-
times outside the nuclear membrane.
The substance that separates two nuclei after mitosis
comes from the linin spindle.
In the following pages where my own observations are
referred to and it is not otherwise stated, cells, plasmodia,
or tissues were stained with acid haematoxylin after fixation
by Foa's solution: see note at the end of this book. With
this stain pure chromatin is of a deep blue colour.
Ehrlich divided dyes into basic and acid according as
the colouring matter plays the part of an acid or a base
the compound employed (Wilson). Ehrlich's statement
only applies to cover-glass preparations dried and fixed by
heat without the use of reagents (Lee's " Microtomist's
Vade Mecum").
Heidenhain termed the chromatin of Flemming " basi-
chromatin " to distinguish it from nucleoli, cytoplasm, and
other parts of cells which take acid dyes, such as acid fuchsin
and eosin. He concluded that basichromatin is rich
in nucleic acid, which Bayliss defines as a compound of
phosphoric acid with a 5-carbon sugar and a purine derivative.
The staining reactions of nuclei of the same organism
may vary : thus Barrett found in the chytridian Olpidiopsis
Saprolegniae that after the gonoplasm has passed into the
oogonium the nuclei in the resulting oospore stained more
deeply with safranine than they did before fertilisation.
14 PROTISTS AND DISEASE
As Wilson points out, there is no specific stain for
chromatin. Similar staining reactions do not necessarily
mean chemical identity ; both the nuclei and matrix of
cartilage stain alike with methyl green.
Staining reactions have their value and we should be
able to make use of every technical resource ; at the same
time we must not forget that a process which reveals one
feature brilliantly will conceal others of equal importance ;
nor that technique is a means, not an end.
Bodies suspected of being protists should invariably be
first carefully examined unstained in conditions as nearly as
possible like those in which they are discovered, and then in
water. In this way alone can we let them show by their own
activities if they are living organisms. They should also be
tested by attempting cultures in water as described below in
Chapter VI.
Intravital Staining. Methylene blue, neutral red, and
other dyes are used to stain living tissues and organisms.
Their applicability is limited ; it is generally agreed that
when a nucleus takes a stain it is dead. Neutral red stains
granules, and it has the advantage of being a test of acid or
alkaline reaction, becoming brighter red with the former,
yellow with the latter. It is a basic dye, its name referring
to its tint. Janus green (Hoechst) has been found to stain
the mitochondria of living human lymphocytes ; mitochondria,
being soluble in alcohol, chloroform, and ether, are destroyed
by the ordinary processes.
FOUNDATIONS 15
Medicine a Branch of Biology. Members of the medical
profession have direct access to a wide field of biological
experience and material from which the academic biologist
is debarred. Our daily study of our patients is a biological
occupation. Each advance a doctor makes in skill is a
biological achievement. If such advance is a discovery new
to his science, and is published, it is a contribution to the
humane applied biology we call Medicine. " Pathology is
by no means the smallest branch of that beautiful science
biology," Virchow wrote in 1855.
To have in the foundations of our consciousness the
well-established principles of general biology is necessary to
every medical practitioner. But principles cease to guide
if they are not revived from time to time by personal experi-
ence ; to spend an occasional hour or two watching with the
aid of a microscope living algae, fungi, Mycetozoa, etc.,
brings real refreshment. In order to be able to share any
new knowledge we may gain in matters that pertain to
general biology we must use terms that cannot be misunder-
stood ; for this purpose we must learn the rules of technical
biological conversation, and by so doing we shall obtain for
ourselves the key to the treasures stored in systematic
biological literature. The responsibility of instructing the
rest of the community on the subject of disease must be
ours. Ours also is the duty of investigation ; lay biologists
have voluntarily come to our aid from time to time ; and
too often from being untrained to know or to counter the
16 PEOTISTS AND DISEASE
dangers that they ran, their zeal has cost both them and us
their lives.
Classification or Taxonomy. Any collection of objects
can be classified in various ways ; e.g. by size, shape, or
colour. Classification is abstract, artificial : as Delage
and Herouard have written, " Only individuals exist." Ai]
the same we know that without systems of grouping there
could be no natural science. On this subject Huxley may
be quoted : " Each such assemblage is in fact a ' natural
order ' in the sense in which that word is used by botanists,
and although the number of these natural orders may be
increased by the discovery of new forms, or diminished by
the ascertainment of closer bonds of union than are at
present known to exist between the orders already dis-
criminated, yet the morphological types which they repre-
sent will always remain, and therefore the knowledge of
their characters, once acquired, will be a permanent
possession.''
As far as knowledge allows organisms are grouped
according to the stock they come from ; their stirpes, as
John Ray (1628-1705) called them. Ray was the first to
distinguish in flowering plants the two groups, mono- and
dicotyledons.
After the publication of Darwin's " Origin of Species "
in 1859, classification became more consciously guided by
phylogeny.
The immense array of living organisms is first broadly
FOUNDATIONS 17
separated in our minds into the two kingdoms of plants and
animals respectively.
The animal kingdom is divided into two sub-kingdoms
or phyla, the protozoa and the metazoa. Botany has no
group that corresponds exactly to protozoa, indicating a
division in which the greatest structural differentiation is
reached in unicellular bionts. The term protophyta was
used by Sachs to denote a joint group of algae and fungi ;
blue-green algae (Cyanophyceae) like Chroococcus, Nostoc,
&c., and green algae (Chlorophyceae) such as Pleurococcus ;
together with the bacteria and yeast-fungi.
The Thallophyta in botany are a section of the cryptogams,
and include all plants lower in organisation than the mosses.
The body of such plants is termed the thallus (Gr.^green
bough). The vegetable protists include Sachs's Protophyta
and filamentous algae such as the Ulotricheae, the Conjuga-
teae (Zygnemieae, desmids, and diatoms), and others such
as Vaucheria, which produce oospores, together with the
corresponding fungi, Phycomycetes, and a number of other
groups of algae and fungi. The commoner grouping of
organisms in descending scale is into classes, orders, genera,
and species ; secondary groups being intercalated as affinities
require. The terms genus and species as defined by
Linnaeus are unchangeable ; as regards the remainder
custom varies with different authors, but the terms class and
order are fairly constant in application.
In botany names of orders are Latin adjectives ending
2
18 PROTISTS AND DISEASE
in -ae with " Plantae " understood ; e.g. Rosaceae^ompositae.
For cryptogams the ending -ales is also used.
The word family was first used as equivalent to order ;
so by J. H. Balfour (1855), and so in the British Museum
' Handbook of British Lichens,' 1921 ; but in Bennett and
Dyer's Sachs (1875) we read " Smaller groups which are
called families," and some writers still follow them.
The class is always a wide group. All the Protozoa are
made into only 4 classes : Rhizopoda, Flagellata, Sporozoa,
and Ciliata. All the plants fall into 4 great groups :
Phanerogamae (flowering plants), Pteridophyta (ferns &c.),
Bryophyta (mosses &c.), and Thallophyta (algae, fungi,
lichens &c.). The secondary groups of Thallophyta: algae,
fungi, lichens, Mycetozoa, &c., constitute each a class.
As to the proper term to apply to the next subdivisions sub-
class is obvious ; between it and the order groups are
variously named ; series (desinence -eae) and sub-series
(desinence -ineae) are convenient terms.
In grouping the protists the Mycetozoa must be given
a central position as being about equally animal and vegetable
in constitution, and we may arrange on one side of them a
series of vegetable, and on the other side a series of animal
protists.
Terminology. The names used for different phases and
organs of protists are complicated by some groups being
included both in botany and zoology. The well-known
Volvox is an alga in botany, a phytoflagellate in zoology.
FOUNDATIONS 19
In botany its motor organs are termed cilia, in zoology
flagella. There is no essential difference between the organ
indicated by cilium (eye-lash) and flagellum (whip-lash),
but it is useful to use words to distinguish the single or few
motor organs of the Flagellata from the relatively smaller
and more numerous organs of the Ciliata. In this book the
word flagellum will be used for motor organs of the zoo-
spores of algae, and Phycomycetes, <fcc., where " cilium " is
usually written.
Difference in the use of terms is nowhere more marked
than in the use of the word " spore." In zoology it is now
but little used : asexual reproductive elements are merozoits
to distinguish them from sexually formed sporozoits. What
used to be called a spore in gregarines is now a sporocyst, and
its contents sporozoits. In Myxosporidia and Haplosporidia
the first subdivisions are pansporoblasts, which produce the
sporoblasts or spores. Pansporoblasts with many minute
spores recall the sporangia, which are grouped in the sorus
of synchytrians.
In botany there is need of names for a wide range of
reproductive elements. De Bary gives an account of his
interpretation of the word spore. Though known in a
general way respectively as zoospores and spores the asexual
reproductive cells of algae are termed gonidia (Gr. gone,
offspring), and of fungi, conidia (Gr. konis, dust). The
term swarm-spore is sometimes used as equivalent to zoo-
spore. The fertilised ovum, as in Vaucheria, is called an
20 PKOTISTS AND DISEASE
oospore ; the fused gametangea of Mucor, &c., form a
zygospore.
When the spore of a fungus germinates by the formation
of a promycelium from which arises reproductive elements
different in shape from the ordinary conidia they are called
sporidia.
Nomenclature. It is imperative that there should be a
uniform system of names in biology. The binominal or
Linnaean system is universally adopted. Linnaeus (Carl A
Linne, 1707-1778) defined his system thus:
"Diagnosis sic plantae consistit in affinitate Generis et
in discrimine Speciei. Nomen plantae itaque, ut utramque
diagnosin indigitet, duplex erit : Genericum, cognomen
gentilitium. Specificum, Praenomen triviale. ' '
At the International Botanical Congress, 1905, it was
recommended that specific names begin with a small letter,
except those which are taken from names of persons (sub-
stantives or adjectives) or those which are taken from generic
names. This was to apply to the vascular plants in particular.
The Medical Research Council (' Notes upon the Pre-
paration of Monographs, &c.,' 1921) directs that all specific
names be written with a small initial letter, even when they
are formed from the names of persons or places. This is
the practice in zoology. Thus in the British Museum ' Guide
to the Mycetozoa ' (1919) we read Diderma Trevelyani, and
Eeticularia Lycoperdon ; and, in zoology, Trypanosoma
brucei, and Spirochaeta anodontae. The latter method has
FOUNDATIONS 21
the attraction of uniformity, but the other is that usually
adopted by the botanists to whom we owe our knowledge of
the Mycetozoa and the vegetable protists. In this book
specific names are written with small initials except in
Chapter VIII, where, in order to give an example of the
customary botanical method of writing names, these are
written as in A. Lister's monograph on the Mycetozoa.
There is scope for a joint conference of cryptogamic
botanists and zoologists to decide on a common plan of
taxonomy and of nomenclature for protists.
CHAPTER II
SOME ALGAL AND FUNGAL PROTISTS
PROTISTOLOGY has been defined by Pavillard as the compara-
tive cytology of primitive forms of life. It is this and more :
it includes the natural history of the organisms, and, when
they are parasites their relation to their hosts.
Algae
With the known exception of one parasitic species noticed
below, all algae contain chlorophyll and so have that most
important of all physiological properties, the power of
decomposing C0 2 in sunlight, the oxygen being liberated and
the carbon either used in metabolism directly or built up
into starch, C 6 Hi 5 , as reserve nutriment. In a word
they are holophytic, except one or two parasitic species.
The starch in many cases is deposited in chromatophores
in refractive bodies, called pyrenoids, which stain purple,
blue, or even black with iodine solution. A few typical
algae and fungi may now be reviewed briefly in order to
lead up to a closer study of some of their congeners, which
are pathogenic to man,
22
ALGAL AND FUNGAL PROTISTS 23
Ulothrix zonata is to be found in spring and summer
attached to stones and other objects near the surface of slow
streams or ponds ; if brought in the morning from a cool to
a warm place, it forms its reproductive elements. A fila-
ment mounted in water and covered may show both macro-
and microzoospores, Fig. 3, A ; ma, mi ; from two to eight
of the former, and from four to sixteen of the latter being
produced from a single cell. The macrozoospores, which
have a contractile vacuole, sink, and lose their flagella, in
place of which an organ of attachment or rhizoid is developed,
the element germinating directly as a new plant, Fig. 4, A.
The microzoospores conjugate by their anterior ends, then
lose their flagella, coalesce completely, and the resulting
zygospore secretes a cell- wall and matures slowly for germi-
nation next spring. In other terms the microzoospores
are gametes, their fusion is isogamy, and the zygospore is a
zygote. Both kinds of zoospore in Ulothrix are at first
enveloped in a thin capsule which is ruptured to allow the
active cell to escape. The same feature is observed in the
zoospores of the fungus Achlya, Fig. 4, C.
The macrozoospores of Ulothrix correspond to the
parthenogonidia of Volvox, the sexual elements in the latter
being differentiated as oogonia and spermatozoids.
Another alga, Vaucheria sessilis, is a species belonging
to a group called the Siphoneae. It grows on damp earth
and can often be found in greenhouse flowerpots, and a
plant is easily isolated by unaided vision. The thallus is a
24
PROTESTS AND DISEASE
tube, simple or branched, at first without septa. It is
usually sparsely branched and some of the branches may
be modified into rhizoids, Fig. 3, B, r. The protoplasm
lines the cell- wall and contains nuclei in its inner layer, and
Fid. 3. SOME ALGAE AND FUNGI. A, diagram of a filamentous alga;
ma, macro-, mi, microzoospores ; B, Vaucheria ; r, rhizoid ; z, zoo-
gonidium ; a, antheridium ; o, oogonium ; C, end of a hypha of
Achlya ; sp, spores ; a, antheridium ; o, oogonium ; os, oospores ;
D, end of a Saprolegnia filament infected by Rozella septigena ; E,
later stage of an infected hypha ; ps, parasitic segment ; o, o, openings
whence zoospores have escaped ; rs, resting spores of Rozella ; c-d,
after de Bary and M. Cornu.
chlorophyll corpuscles and oil-drops externally. The middle
of the filament is occupied by a sap-vacuole.
This arrangement, a multinucleate non-septate con-
dition seen in Siphoneae, is also found in Phycomycetes
ALGAL AND FUNGAL PROTISTS 25
such as PytJiium. Such organisms are termed coenocytes
(Gr. &omos=shared in common).
Those who can recall their early botanical studies may
remember what happens when a Vaucheria is incised under
water ; part of the protoplasm oozes out in lobed masses,
which show amoeboid movements for from half an hour to
an hour. A sharply, often doubly contoured skin-layer or
ectoplasm, like that seen in the mycetozoan plasmodium is
the surface of this naked protoplasm, portions of which
may become detached as rounded bodies, in which vacuoles
appear. The layer of protoplasm limiting a vacuole is called
the vacuolar membrane or tonoplast. Many of the amoeba-
like fragments disintegrate, but some which contain nuclei
renew their growth and secrete a new cell-wall. When
Vaucheria sessilis is grown in water in sunlight vegetative
reproduction by zoogonidia occurs. These are multinucleate
bodies with a pair of flagella opposite each nucleus. A
terminal part of a filament is shut off by a septum before
the zoogonidium is formed, and the motile body escapes by
an aperture in the cell-wall. This happens when the plant
is exposed to light after being in the dark for some hours.
After swimming awhile the zoogonidium sinks, loses its
cilia, secretes a cell-wall, and germinates by one or more
sprouts. The zoogonidium remains as a permanent part of
the thal]us thus developed.
Sexual reproduction is by gametangia : an antheridium
and one or two oogonia are formed as lateral branches shut
26
PROTISTS AND DISEASE
off by septa, Fig. 3, B, a, o, and Fig. 4, B. The gametangia
appear in the evening and are complete next morning.
The modes of reproduction of Volvocineae and of Hydro-
dictyon (the water-net) should be recalled. In the latter the
contents of a single cell divide simultaneously into from
7,000 to 20,000 zoospores, which join together to form a new
net (Bower). A cell of the same organism in its sexual
FIG. 4. STAGES OF SOME ALGAE AND FUNGI. A, diagram, or, of algal
macrozoospore and young plant, and, 6, of conjugation of micro -
zoospores and resulting zygote ; B, Vaucheria, empty antheridium,
oospore, and antherozoids ; C. conidia of Achlya changing to zoo-
spores, b ; germination of oospore ; and ; a, the first form of a zoospore
of Saprolegnia, the second being like b ; D, stages in the germination
of the resting spore of a cladochytridian, a, end view, b, side view,
c, sporangium forming, d, zoospore ; C and D after de Bary.
phase produces upwards of 30,000 zoospores which conjugate
in pairs or greater numbers (van Tieghem).
The cells of simple green algae, e.g. Pleurococcus, vul-
gar is, are arranged in twos, fours, &c., or separately from
one another. Pleurococcus shows as green powder on tree-
trunks, &c. Its cells have nuclei and chromatophores. In
some young algal cells chlorophyll seems to impregnate
ALGAL AND FUNGAL PROTISTS 27
the whole cytoplasm, there being no chromatophores.
Some algae grow in pure cultures like bacteria. Charpentier
found that Cystococcus humicola grown in a liquid medium
containing 1 per cent, of glucose besides the usual salts (phos-
phates, nitrates, and sulphates) would live in the absence of
light, taking its carbon from the glucose. Grown in the
light the plant multiplied more rapidly and produced no
starch, which was abundant when the plant was grown in
the dark. He regards Cystococcus as a " plante de passage "
prepared to adapt itself to a mode of life like that of the
fungus, Mucor.
Able to take carbon from the air green algae seldom
adopt a parasitic life, but one of them, Chlorochytrium
lemnae is parasitic on duckweed. The genus was founded
in 1872 by Cohn, who, as B. M. Bristol informs us, described
it as follows : " Endophytic green unicell, in which multi-
plication takes place by means of numerous zoogonidia
produced by free cell-division, first into large segments,
later into innumerable pear-shaped bodies which are ex-
truded through the tubular process on the cell- wall." The
nucleus in Miss Bristol's illustration is central and has a
large nucleolus.
Another parasitic alga, Rhodochytrium spilanthidis,
deserves close attention. It resembles the fungi in being
devoid of chlorophyll, and is strictly parasitic. Common in
N. Carolina and Equador it has been reported in only one
other district. Rhodochytrium occurs in different host-plants.
28 PROTISTS AND DISEASE
To the naked eye it appears as a small bright red spot,
as told us by B. F. Griggs, some of whose illustrations are
copied in Fig. 5. It developes starch abundantly, the grains
being built up in the protoplasm as Charpentier found to
be the case with Cystococcus.
The colouring matter is a lipochrome. The plug at the
surface end, Fig. 5, C, p, melts away when the ripe sporangium
is placed in water. Rhodochytrium is not an intracellular
parasite like Woronina and Rozella, but it makes room for
itself in the intercellular spaces of the host plant. At its
broad deeper end it pushes out rhizoids, which are shut off
by septa when the alga becomes either a resting-spore or a
zoosporangium. The smallest resting-spore is 70ju long.
At maturity the nucleus of the resting-spore shrinks, Fig. 5,
B, or collapses, to expand again when the spore germinates
in water. The zoosporangium has other peculiar nuclear
characters : on entering the host-tissues the nucleus in-
creases rapidly in size, from 4 or 5/x in the zoospore to 50 or
60 ju, in the zoosporangium ; such a growth of a nucleus is
only equalled in Synchytrium. It is not in size alone that
the nuclei of Rhodochytrium recall those of Synchytrium :
the peculiarly large nucleoli, Fig. 5, D, and the disordered-
looking primary mitosis, E, have a likeness to features in
Synchytrium. Now, though Rhodochytrium, an intercellular
parasite, is different in habit from the intracellular Synchy-
trium, these nuclear processes show that there is a probable
near kinship.
ALGAL AND FUNGAL PROTISTS
29
If we compare the parasite, A, with a zoospore, G, a
great difference in size is apparent, but the protoplast l in A
FIG. 5. RHODOCHYTRIUM SPILANTHIDIS. A, form of the parasite destined
to become a resting spore, rhizoids not in the section ; B, segment of
a ripe resting spore, with shrunken nucleus, starch grains, and triple
capsule ; G, form of parasite destined to become a zoosporangium, a
large vacuole occupies the outer half, and a thickening in the form of
a plug closes the surface end ; D, a resting nucleus, a large nucleolus
and beads of chromatin on linin threads, from a half-grown zoo-
sporangium ; E, the primary mitosis, at one end of the spindle the
aster is wanting, and there are coarse linin threads and chromatin
masses outside the spindle ; F, the last mitosis and the two last
states of subdivision ; G, zoospore ; H } conjugation of two zoospores.
Reduced to |, after R. F. Griggs.
is only slightly larger than that of the zoospore ; the increase
in size is due to large vacuoles filled with cell-sap.
1 The term protoplast in botany signifies the active protoplasmic cell-contents,
i.e. the nucleus and cytoplasm of nucleated cells (Hanstein, 1880).
30 PROTISTS AND DISEASE
That this non-chlorophyllous plant can produce starch
is explained by its being a parasite and using the juices of
its host for nutriment.
Fungi
Fungi never possess chlorophyll and hence, like animals,
they are entirely dependent for their nutrition upon organic
matter, living or dead. They do not produce starch, though
some possess glycogen, which, like starch, is easily converted
into sugar.
Fat, either as granules or oil drops, is the principal
substance they store as reserve nutriment. The dry thallus
of Penicillium after completion of the vegetative period
contains 50 per cent, of fat. The oil of many fungi is coloured,
constituting lipochrome.
The Phycomycetes include such genera as Saprolegnia,
Peronospora and Mucor. The name was given them by de
Bary from their affinity to the algae. The Chytridiineae
have since been included in this group.
Saprolegnia. All species of this genus are aquatic, the
thallus being attached by a rhizoid to decaying matter.
One species is found as an epiphyte on ulcers of diseased
salmon. The hyphae may be | inch long. Dying gold-fish
are often covered with a woolly growth of Addya prolifera.
These fungi are very like Vaucheria in organisation. To
obtain specimens place some dead insects or boiled white of
egg in a quart of pond water. After 24 hours rinse in clean
ALGAL AND FUNGAL PROTISTS 31
water and transfer to tap water. Sporangia appear in
24 hours (Chamberlain). The thallus is normally an
undivided sac, simple in Saprolegnia, branched in Achlya.
Septa are formed to shut off reproductive organs or to
repair injury.
In agamic reproduction the end of a filament swells as a
long sporangium, a septum isolating its contents, which
subdivide into many uninucleate segments. In Saprolegnia
these escape directly as bi-flagellate zoospores, in Achlya in
a mass held together by a jelly, Figs. 3 and 4.
The large sporanges of Saprolegnia with their central
vacuole, cylindrical or irregularly linear, according to the
thickness of the protoplasm, lend themselves to the study
of the mode of origin of zoospores ; this has been described
by M. Hartog and others ; seeing that corresponding stages
are seen in Pythium and Chytridiineae, the leading features
may be enumerated, following E. J. Butler's account :
1, Preliminary separation of spore-origins by concentration
of protoplasm around each nucleus, linear vacuoles occupying
the intervals ; 2, homogeneous stage caused by swelling of
spore-origins and disappearance of the sporangial vacuoles ;
this stage has been explained as being due to rupture of the
skin-layer admitting water to the spore-origins ; 3, vacuo-
lation ; in the origins are formed a number of vacuoles,
which grow, fuse, and disappear ; discharging water into the
exterior where the escaped cell-sap attracts bacteria ;
4, final separation of zoospores by surface grooves meeting
32 PROTISTS AND DISEASE
newly-formed linear vacuoles, which re-appear in the
protoplasm.
In Saprolegnia the zoospores leave the sporangium as
motile egg-shaped bodies like those of algae, Fig. 4, C, a.
They have two flagella at their narrow end which is foremost
in progression, and three vacuoles in the granular plasm.
After a few minutes the zoospore comes to rest, its form
changes to a sphere and a cell-wall of cellulose is secreted.
After some hours or even days the contents escape again as
a zoospore, this time kidney-shaped like those of Achlya.
The second mobile stage may be omitted, the spore germi-
nating directly as a hypha.
This transformation in the zoospores of Saprolegnia is
termed " diplantish " byde Bary, suggesting that at different
stages the zoospores gave the impression that they belonged
to two different plants. The somewhat consonant term
" diplanetism " is now applied to the same phenomenon,
signifying a double period of motility.
In Dictyucus the zoospores instead of escaping from the
sporangium in one mass are retained in the sporangium
where they germinate and escape by penetrating the
sporangium wall, or, failing in this, they perish, the fate
of the majority.
Resting conidia. In old growths, especially of Sapro-
legnia, the thick hyphae break up transversely into segments,
which are cylindrical, round, or barrel-shaped. These seg-
ments are resting conidia ; they are rich in protoplasm and
ALGAL AND FUNGAL PROTLSTS 33
often have thick walls. In AMya prolifera de Bary saw
them form acrogenously. They germinate either in clean
oxygenated water or in suitable nutrient fluids, producing
either new hyphae or sporangia.
In the sexual process antheridia and oogonia are formed
and shut off by septa. The contents of the oogonium
divide into several oospores, which require a variable time
to ripen. They germinate by forming a sporangium, which
produces a bunch of conidia, which become zoospores,
Fig. 4, C.
Biologic forms of Fungi. Before passing to the con-
sideration of some parasitic fungi the subject of what is
known as biologic variation should be mentioned. The
facts have been well stated by Massee as follows : "In the
case of many parasitic fungi certain members of a given
species have become so modified and specialised in their
parasitism, that they can only infect a given species of host-
plant, or, at most a few closely allied species.
" Such are termed biologic forms, on account of their
speciality in this direction being of a purely physiological
nature. ... No morphological differences are presented by
biologic forms belonging to the same species. . . . The
morphological species called Erysiphe graminis is parasitic
on barley, oats, wheat, and many wild grasses. Culture
experiments have proved, however, that the particular
form parasitic upon any one of the plants enumerated above
cannot infect any of the other plants."
3
34 PKOTISTS AND DISEASE
Parasites of Saprolegnia. Chytridian parasites such as
Woronina and Eozdla often occur in cultures of different
species of Saprolegnia. It is Eozella that causes the curious
septate condition shown in Fig. 3, D and E. The number
of compartments found in any one filament varies ; it
depends on the number of parasites that penetrate : the
more the parasites the more the compartments, though not
in strict numerical proportion because fusion of parasites
occurs. Each compartment is a sporangium of the parasite,
its wall adherent to the cell- wall of its host. The zoospores
of the Chytridian are evacuated in from 60 to 90 hours after
infection through a hole at the side, Fig. 3 ; E, o, o. Resting
spores are also formed: lateral shoots are protruded and
typical chytridian resting spores are formed, causing a
curious resemblance to the hosts' ovum in the ovary, as in
Fig. 3; E, rs ; but Cornu noticed that the protrusion
containing the parasite is not shut off by a septum as the
ovary is.
Peronosporeae. The next group of the Phycomycetes
is called the Peronosporeae, and includes the genera Pythium,
Peronospora, Phytophthora, and Cystopus.
Pythium. The genus Pythium was founded in 1858
by Pringsheim as subordinate to Saprolegnia ; the aquatic
species having been studied before the terrestrial. The
genus is a small one (18 species) though of world- wide
distribution. Butler found in pond-water in India the
same species as he had found in England. Pythium affords
ALGAL AND FUNGAL PROTISTS
35
a basis for comparison with algae and with kindred genera
of primitive fungi. Facts mentioned below combine to
make this genus one of the most important for practical
study.
Specimens of water-species can be obtained by the same
a
FIG. 6. PYTHIUM. a, seedling of cress, the arrow points to the part
invaded by the parasite ; 6, end of a hypha which has pierced the
wall between two host-cells ; c, conidia of Pythium debaryanum,
above, ripe terminal, below, early interstitial ; d, oogonia and an the -
ridia, above early stage, below, oosphere contracting, fertilisation
canal formed ; e, two stages of the germinating zoosporangium of
P. proliferum ; f, zoospores. Portions of Marshall Ward's illustra-
tions.
means as Saprolegnia, a slice of raw potato makes a good
substratum. One sub-genus, Aphragmium, by its mode of
reproduction is very like a filamentous alga : without septa
even being formed, an unaltered portion of its mycelium is
transformed into zoospores, which escape at a hole in the
wall. The slender pythium-filaments are multinucleate.
36 PROTESTS AND DISEASE
Writing of the genus Pytkium in general Dr. E. J. Butler
states : " All the species which have been investigated are
capable of living saprophytically. Many are capable in
addition to attack and destroy living tissues ; but they are
hemisaprophytes, for even the most destructive, P. de-
baryanum (Hesse), attains its maximum development -and
reproductivity when cultivated saprophytically."
One species has been found to attack and destroy the
vinegar eelworm ; the body of which was filled with very
fine hyphae. In this P. anguillulae aceti sporangia,
conidia, and oogonia formed at the same time, not in
succession.
Parasites of Pythium. The kindred of Pythium include
the Chytridiineae, and it happens that fungi of this latter
class often infect common pythiums, so that likenesses and
differences between host and parasite can be studied ; but
care not to mistake normal for parasitic features is required :
thus of a species of Pylhium that kills palm-trees Butler
wrote : " The hyphae are at first always unseptate and
crowded with a dense protoplasm. Fat is abundant,
glycogen also occurs in highiy-refractive droplets, whose
resemblance to Chytridiaceous fungi, parasites of the genus,
is remarkable."
Pythium debaryanum. In any sowing of cress on garden
soil a few seedlings may be found bent down. The stalk is
narrowed at the bend : such a plant straightened is shown
in Fig. 6 ; a, where the narrow invaded part is indicated by
ALGAL AND FUNGAL PROTISTS 37
an arrow, the interrupted line showing the level of the soil.
If seed is sown thickly on soil half filling a flower-pot and
kept well watered and covered by glass nearly all the plants
may be affected. Gardeners call this " damping off."
Bower describes the last stage thus : " If the cress culture
be kept damp for some days longer, a thick felt of hyphae
will be formed, which will bind the seedlings together : and
finally the disorganisation will spread throughout the seed-
lings, causing complete rotting." In a sowing made on
sterilised sand I found that no infection occurred.
Marshall Ward found that a healthy seedling placed in
water beside a diseased one was infected in from 12 to 24
hours. The hyphae of Pythium are not, like those of Sapro-
legnia, content to form an attachment by a rhizoid, they
penetrate and traverse the host-cells, Fig. 6, b ; and ramify
in and between them and on the surface of the plant. " The
cells are killed very shortly after the fungus reaches them,
and there is no attempt to react in any way to the invading
organism ; no hypertrophy appears nor any attempt at
cell-division " (Butler).
An infected cress-plant placed on a slide shows numerous
delicate non-septate hyphate, which after a day or two will be
found to have round swellings at the ends of some hyphae
and round or oval swellings in the course of (interstitial or
intercalar) other or the same hyphae. These swellings at
first look very much alike, but soon in some a large vacuole
and a beak-like process of the inner wall develope, Fig. 6, e,
38 PROTISTS AND DISEASE
showing that it is a sporangium ; the other imspecialised
swellings are called conidia ; in shape these are not at first
different from the oogonia, but the latter appear a little
later than conidia and are soon distinguished by the presence
of an aiitheridium, Fig. 6, d, near each of them, and the
subsequent formation of encapsuled oospores within them,
Fig. 7, /. Left alone the conidia remain dormant, and they
are able to resist frost, but not complete desiccation.
If fresh oxygenated water be added they germinate by
extrusion of the endospore into a hypha. If they are detached
as soon as ripe and placed in fresh water they produce each
a brood of zoospores. We have seen that a single zoospore
of Saprolegnia could be replaced by a hypha, and here it is
seen that a single Pythium-hypha may be replaced by a
group of zoospores. Some conidia of P. debaryanum have
the power of remaining dormant for long periods, and such
are at times distinguished by a slightly thicker wall, and
are termed " resting conidia."
Sporangia germinate as a small brood of zoospores, if
they are supplied with plenty of well- oxygenated water in
a strong light. The stages are like those of Saprolegnia
with an additional feature, the distension of the apex of the
beak into a bubble or vesicle by cell-sap, and the passage of the
sporangial protoplasm into the vesicle there to break up
into zoospores, Fig. 6, e. Rotation occurs before the proto-
plasm passes into the vesicle during the stage of early
segmentation ; the homogeneous stage occurs about 5
ALGAL AND FUNGAL PROTISTS 39
minutes before the vesicle is formed. In the vesicle a rolling
of the contents is observed before subdivision,
Zoospores are at first amoeboid then kidney-shaped with
2 flagella attached at the hilum. They escape by rupture
of the vesicle, and tend to collect at the surface of the water.
They become encapsuled before germination ; diplanetism
has been observed by Butler in one species.
In most species germination is by a branched hypha, but
in P. tenue and others parasitic in Vaucheria, Spirogyra,
&c. the encysted zoospore having settled on a host filament
forms a penetration-tube like that of some olpidians.
The gametangia, Fig. 6, d, and Fig. 7, consist of a round
oogonium and an antheridium which arises close to the
oogonium from the same hypha or from an adjoining hypha.
The tip of the antheridium touches the oogonium into
which it sends a process, the fertilisation canal, through
which in hanging- drop cultures the gonoplasm can be seen
to pass.
The brooch-like arrangement of the gametangia is the
origin of the name of the group. Sometimes two or more
antheridia are attached to the same oogonium.
Amoeba-like movements of the oosphere in the course
of preparation for fertilisation are described by Marshall
Ward, who observed that the passage of the antheridial
contents requires about an hour. The periplasm from
which the outer wall of the oospore is formed is scanty.
The ripe oospore of Pythium after a long resting period
40
PROTISTS AND DISEASE
germinates in water by developing a hypha. In some
kindred genera, e.g. Cystopus, Fig. 8, g, the oospore pushes
out a process which becomes a zoosporangium.
Nuclear Processes in Pythium. The nuclear changes
in the sexual process of Pyihium,, Fig. 7, have been studied
by A. H. Trow, and by Kiichi Miyake (1901). Young
oogonia measure from 20/x to 25/a,, their nuclei are larger
FIG. 7. NUCLEAR PROCESSES IN PYTHIUM DEBARYANUM. a, young
oogonium ; b, nuclear divisions in both oogonium and antheridium ;
c, early anaphase, from oogonium ; d, one nucleus in each game-
tangium is intact, the rest disintegrating ; e, passage of male nucleus
into oosphere ; /, ripe oospore with membrane and end of empty
antheridium. After Miyake, reduced to ?.
than those of the hyphae. When the ovum is nearly mature
its nuclei divide by karyokinesis, and all save one move to
the membrane and disintegrate, d. The spindle is intra-
nuclear. Eight chromosomes were counted ; the author
could not detect a reduction. The remaining nucleus lies
in the middle of the ovum. Events in the antheridium are
similar to those in the oogonium.
Near the single remaining nucleus of the oosphere
A. H. Trow observed the formation of a, coenocentre in
P. ultimum.
ALGAL AND FUNGAL PROTISTS 41
" The wall of Pythium is usually assumed to consist of
cellulose. However, as Trow has observed in the case of
P. ultimum, the cellulose reaction is often difficult to obtain.
The blueing with chloriodide of zinc is often faint or only
got after long treatment " (Butler).
Phytophthora infestans is the cause of " blight," the
most serious disease of the potato. The leaflet issued by
the Ministry of Agriculture and Fisheries tells us that it was
first noticed in Europe and America in 1840 and that it
caused famine in Ireland in 1845. It is now always present
in the British Isles. The mode of entry into the host-plant
is shown in Fig. 12, a. The first sign of the disease is the
presence of brown or black patches on the leaves, which look
as if charred in places.
At the margin of these places on the under side of the
leaf, and, in wet weather, on the upper side also, a white
powder is seen. This whiteness is the conidia, which are
borne on branched stalks pushed through the stomata from
within. Conidia germinate in the same way as those of
Cystopus, Fig. 8, 6, c.
Details of the nuclear processes in a kindred species,
Phytophthora erythroseptica, which also destroys potatoes,
are given by P. A. Murphy (1918). The oogonium is peculiar
in that it pierces the antheridium to develope on its farther
side. Nuclear reductions occur leaving one nucleus in each
gametangium, these nuclei coalesce to form the single
nucleus of the oospore as in Pythium,.
42 PROTISTS AND DISEASE
Cystopus candidus. This fungus, which is parasitic in
Crucifers, is a common parasite in the weed, shepherd's
purse ; it attacks also crucifers of economic value : cabbage,
radish, horse-radish, cress, &c. The conidia form beneath
the epidermis causing the appearance known as " white
rust." They are really sporangia, which, on germination
under water, produce a number of bi-flagellate zoospores.
These in turn lose their flagella and germinate as shown in
Fig. 8, d.
Details of structure in Oospores. In Pyihium the oospore
or fertilised ovum, Fig. 7, /, secretes a stout cell- wall inside
that of the original oogonium ; there is but little periplasm,
and no thick exospore is produced. In Cystopus candidus
a thick exospore is formed from the periplasm. After a
long resting period the oospore germinates in water as is
shown in Fig. 8, g, h : the innermost wall of the spore bulges
with its contents, becoming a sporangium, from which
zoospores escape.
Nuclear processes in Cystopus. In C. Candidus the
gametic nuclei behave as in Pythium, and there is an
additional feature in the presence in the ovum of a deeply-
staining body, the coenocentre, Fig. 8, i, which, as Wager has
suggested, may be the equivalent of a vegetative chromidium.
In C. bliti the nuclei of the gametes subdivide mitotically
and conjugate in pairs.
A second simultaneous division of nuclei occurs in the
oosphere before fertilisation.
ALGAL AND FUNGAL PROTESTS
43
The greater the number of nuclei that remain in the
ovum of any species, the smaller is the coenocentre.
Equivalence of a germ-hypha to a brood of Zoospores
in Phycomycetes. An instance of the equality of germ-
hypha and zoospore has been mentioned above : the first
FIG. 8. CYSTOPUS CANDIDUS. a, end of a hypha with 4 branches (conidi-
ophores) ; 6, germination of a conidium ; c, zoospores ; d, germination
of zoospores ; e, end of antheridium attached to /, the oogonium. the
fertilisation -canal is formed, p, periplasm ; g germination of oospore ;
h, zoospores ; i t part of an early oogonium, showing in the middle
the darkly stained coenocentre and near it 4 mitoses, farther out,
small nuclei, a-h, after de Bary ; i, modified from Stevens.
alga-like form of zoospore of Saprolegnia secretes a capsule
from which either a kidney-shaped zoospore or a germ-
hypha may be produced ; and in Pythium a germ-hypha
may be alternative to a zoosporange. A similar alternative
is found in Phytophthora, the conidia of which in water pro-
duce a group of zoospores, but in nutrient media a simple
germ-hypha.
44 PROTISTS AND DISEASE
Zygomycetes. --This group includes Mucorineae and
Entomophthorineae. The former agree with Oomycetes in
general structural plan, but they differ in the absence of
zoospores and in forming zygospores in place of oospores.
Material for study is easily obtained : a piece of bread
that has been exposed to the air for 2 or 3 days is dipped in
water, placed on a saucer and then covered by an inverted
tumbler ; in 4 or 5 days a growth of mould will appear.
Mucor mucedo can be recognised by its tall unbranched
conidiophores and dark round sporanges. The former are
generally about half an inch long, but I have seen the growth
like a piece of a sheep's fleece with conidiophores nearly
3 inches long.
The mycelium or thallus is non-septate save when
injured or old. Zygospores are formed by fusion of pro-
jections from neighbouring hyphae, Fig. 9. They form
more readily in some species than in others, thus they abound
in Sporodinia grandis, which is parasitic on fleshy Hymeno-
mycetes, such as Bolets and Russulas ; while in M. mucedo
their presence is exceptional. The reason of this was shown
in 1894 by Blakeslee, who discovered that in this and some
other species of Mucor conjugating filaments belong to
different strains of mycelium ; a more vigorous, or +?
mycelium, and a less vigorous, or , mycelium.
If growths of a + and a strain are started on opposite
sides of a culture-plate, they will meet near the middle and
form a dark line of zygospores, seen as black spots projecting
ALGAL AND FUNGAL PROTESTS
45
a little above the substratum. Mucors that produce
zygospores from the same thallus are termed homothallic,
those that do so only from different strains, heterothallic.
S
FIG. 9. MUCOR MUCEDO. M, mycelium bearing two conidiophores ;
C, sporangium with spores, two crystals more magnified, and end of
conidiophore with part of membrane and columella ; 8, 4 spores, the
two lower germinating ; z sp, stages in the formation of a zygospore ;
Z, zygospore, which has germinated by the promycelium ; pm, which
bears a conidiophore. Mainly after de Bary
In M. mucedo, Fig. 9, the conidia are formed simulta-
neously in a sporangium, the wall of which may be beset
46 PROTESTS AND DISEASE
with crystals of oxalate of lime. The septum at the base
bulges into the cavity constituting a columella.
The zygospore requires some months to mature. It
germinates by sending out a single hypha called a promycelium,
which produces a sporange full of conidia, but when the
zygospore germinates in a nutrient medium it forms a
mycelium.
Spores. Two classes of spores are to be distinguished
in fungi by their mode of germination : in one the whole of
the protoplasm passes into the germ-hypha and the empty
capsule is left to decay ; in the second group, that to which
Mucor belongs, the spore retains part of the protoplasm,
grows, and remains part of the developing plant.
Spores of the first group will germinate in water, those of
the second require nutrient media.
Four spores are shown at 8 in Fig. 9 ; the two upper
from a sporangium needled in a drop of water, the two lower
in a weak infusion of plum- jam. Only the latter are changed
being swollen and having a double contour and a central
vacuole. From one a hypha has grown, some neighbouring
spores had two, and others three such. Two days later a
hypha which had eight lateral branches was sketched. In
its central part granules were seen to flow a considerable
distance towards the growing point, and at the same time
other granules were flowing in the opposite direction. Not
more than one per cent, of the spores in this culture germi-
nated.
ALGAL AND FUNGAL PROTISTS 47
Gemmae. Spores of Mucor Mucedo sown on glucose
solution with free access of air produce the usual non-septate
mycelium, and oxygen is absorbed ; but if the growth is
submerged or air is replaced by hydrogen, the hyphae
become septate and break up into segments, which multiply
by budding, like yeast, to form a scum of large cells or
gemmae. This condition is easily produced in M . racemosus.
Alcoholic fermentation is caused by mucors in this state.
Spores placed directly in glucose solution free from oxygen
produce gemmae instead of hyphae. If air is admitted,
gemmae produce ordinary mycelium.
Sporidia grown from promycelia of some species of
Ustilago multiply in a similar yeast-like way in nutritive
media such as manure heaps (Massee). Gemmae were seen
by Butler in PytJiium rostratum. A different sort of element
is also termed a gemma : it is found in old badly-nourished
mucors, and it is produced by a segment of mycelium being
isolated by septa. Such elements are really a sort of conidia.
Parasitic Mucors. One of the parasitic Mucors is
illustrated in Fig. 10. Piptocephalis has for its host a Mucor
of another species. Its haustoria are seen as blunt projec-
tions provided with very fine branches which lose themselves
in the plasm of the host.
Nuclei of Mucor. The tip of a hypha of Sporodinia
Grandis is shown in Fig. 11, a. Its point consists of proto-
plasm without either nuclei or cell- wall. In the rest of the
hypha nuclei are numerous especially near the point, where
48
PROTISTS AND DISEASE
they are very small. They consist of nucleolus, nuclear
plasm, and membrane, resembling those of Saprolegnia,
Ustilago (smut), and Uredo (rust). The nuclei may become
m;
FIG. 10. PIPTOCEPHALIS FRESENIANA. M, hypha of M . mucedo ; m, hyphae
of Piptocephalis ; H, haustoria ; Z, zygospore ; *, suspensors ; z,
stage in formation of zygospore ; c, conidia. Modified from de Bary,
after Brefeld.
elongated in the direction of the hypha. Similar nuclei are
found in the sporangium, the plasm of which surrounds a
vacuole, and subdivides into spores, each of which contains
ALGAL AND FUNGAL PROTISTS
49
several nuclei. In the conjugants similar nuclei crowd the
plasm on each side of the septum, and when the latter has
been absorbed some of the nuclei would appear to fuse in
4 a
FIG. 11. NUCLEI OF MUCOR. a, end of hypha ; 6, conjugation ; c,
\?) fusion of nuclei in zygospore of M. fragilis ; d, resting nucleus with
nucleolus and centrosome ; e, part of sporangial membrane with
spores ; /, mitosis, metaphase, in M . sylvaticus ; g, anaphase in
Phycomyces nitens. a-c after Dangeard, the rest after Moreau.
pairs ; the remainder disintegrate, All the details have
not yet been made clear.
Some Features of Parasitic Fungi. Spores of some
parasitic fungi may go through the first stage of germination
if placed in water, but they soon die unless they are brought
into contact with their proper host. Such organisms are
necessary parasites. The special organs of the simpler
parasitic fungi may be considered before passing to examples
of more intimate adaptation.
50 PROTISTS AND DISEASE
Haustoria, Fig. 12, b, c, are processes growing from a
parasite into or among the cells of a host. They may be
simple and knob-like, or branched. De Bary mentions that
the type of haustoria just referred to in Piptocephalis is
exceptional. The haustoria by means of which the chytri-
dian Polyphagus sucks the juices of its prey must approach
those of Piptocephalis very closely.
Another parasitic Mucor, Chaetodadium, is said (de
Bary) to make direct communications between its own and
its host's protoplasm at apertures where hyphae of host and
parasite are in contact.
Symbiosis. Akin to parasitism is the relation of fungi
to algae in the symbiosis seen in lichens, of which about
2000 British species are known.
In lichens the fungus alone retains the property of sexual
reproduction, the alga being restricted to vegetative growth
by the control of the other symbiont, but when gonidia of
lichens have been isolated and cultivated they have produced
sexual generations.
The hypha of the germinating fungus- spore grows around
its proper alga or algae and the joint vegetation is a lichen-
thallus, Fig. 12, d, e.
Nowhere is the power of protistic life more prominently
shown than by lichens. Towards the arctic Cladonia
rangiferina (reindeer moss) grows luxuriantly making life
possible for beast and man ; and in sub-tropic deserts
Lecanora esculenta grows loosely attached to limestone
ALGAL AND FUNGAL PROTISTS
51
" manna " in case
rocks and, scattered by winds, serves as
of need. This Lecanora when dry is said (A. Lorrain Smith)
to contain over 60 per cent, of crystals of oxalate of lime.
The real nature of lichens was first explained by Schwenender
in 1867, but it was many years before his view was accepted
in England. The word symbiosis was created by de Bary
sp
FIG. 12. SOME FEATURES OF PARASITIC FUNGI, a, Phytophthora infestans,
the zoospore, z, in germinating secretes a capsule which it leaves
and penetrates into an epidermal cell of a potato-plant ; b, end of a
hypha of Cystopus candidus with knob-shaped haustoria penetrating
into a cell of its host ; c, Peronospora calotheca with a branching
haustorium ; d, the beginning of the lichen Physcia parietina, sp,
spore of the fungus which has germinated, its hypha sending branches
round two cells of the alga, Protococcus viridis, p ; e, fungal hyphae
and Protococcus from the lichen Cladonia furcata. After de Bary.
to express the relationship of the two participating organisms
or symbionts of lichens.
Other examples of symbiosis are shown by the zoochlorels,
unicellular algae found in symbiosis with many fresh-
water protozoa and invertebrates ; and by the zooxanthels,
52 PEOTISTS AND DISEASE
cryptomonads, found symbiotic with marine protozoa, &c.
In these cases the symbiosis is not so perfect as that of
lichens : the animal digests its companions when starvation
threatens.
The green or yellow organisms have the structure of
algae : nucleus, chromatophore with pyrenoid, and cell-
wall of cellulose. Their occurrence is not constant in every
species of animal with which they associate. They have
been seen to divide inside their symbionts, and Famintzin
obtained divisions in a slide- and- cover culture.
When infested animals are kept in the dark they eject
their zoochlorels. The latter have been isolated and culti-
vated, and identified with Chlorella vulgaris one of the
Protococcaceae.
Caullery mentions that these organisms also were long
denied their real status in England.
Mitochondria. In the higher animals and plants bodies
which stain like chromatin with iron-haematoxylin are
found in the cytoplasm. These bodies are called mito-
chondria or chondriosomes. They undergo changes in the
vital processes of the cells. Bayliss states that they are
composed of albumen and lecithin. Some of them resemble
bacteria very closely and one of the many theories of cancer,
that of Portier, is based on the assumption that they are
symbiotes, which cause cancer by assuming parasitic
characters. Facts that are recorded below render any
theory of cancer unnecessary.
ALGAL AND FUNGAL PROTISTS 53
The present position of questions relating to mito-
chondria are given by Sharp (1921), who concludes that
some structures included in that term should be regarded
as cell-organs, though, like centrosomes, they may be not
permanent.
CHAPTER III
CHYTRIDIINEAE
THE Chytridiineae, also called the Archimycetes, are a
group of microscopic, parasitic fungi. They are named
from a feature common to them all : propagation by zoo-
spores formed in receptacles, 1 which have walls of cellulose.
Their systematic definition by Engler and Prandtl, 1897,
reads : " Mycelium wanting or in the form of fine proto-
plasmic strands. Sporangia always produce zoospores."
The protoplasm which fills the sporangium is rich in fat.
Considered by themselves they present biological and cyto-
logical features worth careful study ; their affinities to
algae, Peronosporineae, and mucors on the one side, and to
the Mycetozoa and Protozoa on the other give them added
interest.
The genus Chytridium was founded by A. Braun in 1850.
Before that time the sporanges of these parasites had been
mistaken for reproductive organs of their hosts ; a mistake
1 The Greek word chytridion means a little pot, and angeion and soros mean vessel
or urn. In botanical writings the adjective chytridiacean is used ; by a simple elision
I have shortened this, and in this book the words chytridian, olpidian, and
synchytrian are used both as adjectives and nouns.
54
CHYTRIDIINEAE 55
that was repeated in regard to Protozoa as hosts, and was
corrected by Dangeard in 1894, as -is explained below.
One group, the Synchytriaceae, differs so widely from
average fungi and approaches the Sporozoa so closely in
constitution and life-history that errors are likely to have
been made. Most Synchytrians do not appear to inflict on
their hosts more than local damage, but Synchytrium
endiobioticum, by attacking certain kinds of potato
threatened to destroy the crop over large areas of England.
The parasite causes tumours which resemble cancer more
nearly than does any other tumour of plants.
In other Chapters of this book I give reasons for my
belief that the parasites which cause cancer, sarcoma,
syphilis, smallpox, and other diseases in man and animals
are allied to the genus Synchytrium.
Wide differences are found between forms at the extremes
of the Chytridiineae, and, though linking species exist, it
has been doubted whether the grouping represents a natural
affinity, that is a common descent, or merely a likeness of
form caused in organisms of varied descent by their living
under like conditions. De Bary recognised four main groups,
now made into as many orders : Rhizidiaceae, Cladochytri-
diaceae, Olpidiaceae, and Synchytriaceae.
The two former have a mycelium, and hence are grouped
as Mycochytridiinae ; the two latter without mycelium,
hence Myxochytridiinae.
The mycelial forms may be akin to the genus Ancylistes,
56
PROTISTS AND DISEASE
allied to Pyihium in organisation, which attacks single cells
of algae, sending out rhizoids that pierce adjoining cells.
Olpidiaceae agree with Synchytriaceae in other ways
besides the absence of mycelium ; and a descent from an
alga such as Pleurococcus has been suggested ; a view that
has some confirmation for Synchytriaceae in features of
the parasitic alga Rhodochytrium, see above p. 27.
FIG. 13. DIAGRAM OF POLYPHAGUS EUGLENAE AS SEEN ALIVE. The
small circles represent encysted Euglenae on which, the fungus feeds.
1 , mycelial stage ; 2, sporangium with empty section of mycelium ;
8, conjugation, the lower plant is the male, the upper the female ;
commencing zygospore at Z ; 4, the ripe zygospore with parts of
empty tubes ; 5, germination of zygospore, sporangium forming ;
6, zoospore. Modified from de Bary after Nowakowski.
Rhizidiaceae. The first order is illustrated by Polyphagus
euglenae. In this organism, Fig. 13, the zoospore, after a
dancing motion of about a quarter of an hour, becomes
amoeboid, and sends out " rhizoids," resembling filamentous
pseudopodia. The organism creeps about until one or
more of the rhizoids find an encysted Euglena viridis this
CHYTEIDIINEAE 57
they pierce and suck its substance by means of haustoria.
The rhizoids are branched, and each branch may find a victim.
The body of the parasite grows, and part of it bulges into a
more or less cylindrical sac or sporangium, into which all
the protoplasm passes to divide into a fresh brood of zoospores,
which are liberated to repeat the cycle through several
generations.
The passage of all the protoplasm into the sporangium
or into the zygote accounts for the empty tubes seen in
Fig. 13, 2 and 4. Watched under the microscope in the
living state, numerous bright globules, which change in
size and arrangement, are seen in the sporangia : they are
oil drops: Fig. 4, D ; and Fig. 13, 2 and 5. The nuclei
are not so prominent and for the most part are seen only in
stained preparations.
When food becomes scarce conjugation supervenes. In
this process a rhizoid of one amoeboid individual joins the
body of another, and the protoplasm of the two flow to an
enlargement in the joining rhizoid at the point of union to
form a zygote or resting spore, which has a thick wall usually
studded with short spines. After a resting period it germi-
nates forming a sporangium the contents of which subdivide
into zoospores. The oil-drop is absent from the zoospores
of some chytridians.
The zoospores of Polyphagus are phototaxic as are the
Euglenae it feeds on (de Bary).
Wager found that cultures of Euglena obtained from a
58
PROTISTS AND DISEASE
sewage-farm were heavily infected ; their normal grey-
green colour changing first to yellow and finally to a dark
brown. The same author has given a full account of the
cytology of Polyphacjus. The zoospore germinates as soon
FlG. 14. POLYPHAGUS EUGLENAE, NUCLEAR PROCESSES. A, ZOOSpOre
with its nucleus and fat-drop surrounded by a chromidium ; A 1 ,
young plant soon after germination, nucleus and chromidium ;
B, beginning of vegetative spore -formation, half the nucleus is in
the sporangial diverticulum ; C, vegetative sporangium with
4 resting nuclei ; C 1 , a sporangial nucleus at metaphase ; D, conjuga-
tion, some of the chromidial granules of the female (upper) gamete
have entered the swelling which becomes the resting spore or zygote ;
E, zygote, with 2 small nuclei and their chromidia.
after H. Wager.
Reduced to f,
as it conies to rest ; in external form it resembles the common
protozoon Actinophrys, a Heliozoon, and having a well-
marked chromidium it is very like a Khizopod, Fig. 14, A 1 .
CHYTRIDIINEAE 59
The nature of chromidia or collections of extranuclear
chromatin is discussed in Chapters I and TV.
Encysted Euglenae alone are attacked by Polyphagus,
the rhizoids of which may attach as many as fifty. From
the end of the rhizoid a branched haustorium pervades and
soon exhausts the prey. The protoplasm is dense and
contains many oil drops. The nucleus and chromidium
pass with the protoplasm into the sporangial diverticulum.
The chromatin of the resting nuclei is massed at one side
of the nucleus, Fig. 14, C. In mitosis the greater part of
this chromatin lies around the spindle, in optical section
showing as a dark crescent on each side at some distance
from the spindle, Fig. 14, C 1 .
The zygote is formed from two ordinary vegetative
cells ; the male puts out a long slender rhizoid on which a
swelling arises at the point where it comes in contact with
the female gamete, Fig. 14, D. The male nucleus enters
the swelling first, and, after a series of changes in which the
nuclei are reduced in size, the two chromidia fuse into one
mass at the sides of which the two nuclei are embedded.
Fusion of the nuclei appears to occur only after germination
has begun. Nuclear divisions take place only in sporangia.
The chromosomes number 10 or 12 and are very small.
The spindle is internal. The chromatin which surrounds
the spindle is used in part as nutritive material in the growth
of the sporangium. The chromidium surrounds both nucleus
and oil-drop in the zoospore of Polyphagus, Fig. 14, A.
60
PBOTISTS AND DISEASE
2. Cladochytriaceae (Gr. klados = branched). This group
is described by de Bary as having a delicate, rhizoid-like,
richly-branched, wide-creeping mycelium. Nowakowski first
found them in decaying marsh-plants. Sporangia are either
terminal or interstitial.
Of Cladochytrium iridis only resting spores were known,
see Fig. 4, 4.
Cladochytrium graminis " attacks the root and leave
FIG. 15. OLPIDIOPSIS SAPROLEGNIAE. A and B, stages of parasites in
the same host -filament ; C, in a host-filament, the protoplasm of
which is exhausted, are six parasites at different stages, the uppermost
discharging zoospores ; below, zoospores more magnified ; D, part
of a filament with empty sporangia ; E, at the end of a filament are
two parasites with prickle-walls, and spore-ducts ; F, four zoospores ;
G-I, stages of the same three parasites in the same host-filament.
A-D, after M. Cornu ; E-I, after A. Fischer. Reduced to f.
of different kinds of lawn and pasture grasses : the disease
spreads from a centre, killing off the herbage and leaving
naked patches. ... If the dead basal leaves are examined,
the tissues more especially along the edges of the leaf, are
seen to be crowded with the resting spores of the fungus "
(Massee).
CHYTRIDIINEAE 61
Urophlyctis. This genus also belongs to the Clado-
chytriaceae. U. alfalfae causes the crown-gall of lucerne ;
U. leproides, beetroot tumour.
3. Olpidiaceae. This order and the next have been
made for chytridians without mycelium. Olpidians were
first discovered by M. Cornu in Saprolegnia-fil&menis. The
damage they can cause is often very great, e.g. in the disease
of seedling cabbages mentioned below. They are not
entirely restricted to plants as hosts : the kindred Sphaerita
endogena attacks protozoa, and 0. gregarium develops in
the eggs of certain rotifers ; Butler depicts one egg being
attacked by four zoospores, and others filled with sporanges
and resting spores.
The zoospores of some members of the order are uniciliate,
of others biciliate. After swimming for a time zoospores
come to rest as a particle of naked protoplasm, which in
some cases exhibits amoeboid movement for a time before
it becomes of a rounded shape.
If situated on a suitable host-cell a penetration-tube is
formed and the parasite's plasm passes into that of the
host, Fig. 15, G. If they do not find a host quickly they
break up.
Some of the names used for olpidians call for explanation :
species that bear the order-name are in the minority. The
generic diagnosis states that resting sporangia are smooth
and without appendage cell in Olpidium ; this is so in Butler's
drawing of 0. gregarium. In Olpidiopsis saprolegniae the
62 PROTISTS AND DISEASE
resting spores are spinous and have an appendage cell,
denoting a zygospore. In Pseudolpidium, e.g. Ps. Pythii,
there is no appendage cell. In all these three groups all
stages of development from zoospore to sporangium or
sorus, i.e. group of sporangia, or to a resting-spore can be
traced, because the parasite-plasm remains separate from
the host-plasm, and the sporangia are separated by an
interval from the cell- wall of the host.
Very different is the case of Bozella, Fig. 3, D, E 9 where
the individuality of the parasite is lost and its plasm finally
replaces that of the host, of which the cell- wall is inseparable
from that of the parasitic sporangium. The genus Pleol-
pidium was made by Fischer for several species of Rozella.
Woronina, named after the Russian botanist, appears to
differ from Rozella in that its sori lie free in the host-cells.
After the entrance of a single zoospore into a Saprolegnia
from 2 to 14 sporanges of Rozella have been seen to arise.
Plasmodium-formation. A true union of the bodies of
several parasites appears to occur in both Woronina and
Rozella, but even in these genera this fusion is apparently
not a constant occurrence.
When the plasmodium is formed it behaves like a single
organism, becoming either a single sporangium or a sorus
or a resting spore. In the case of Rozella an additional
point of interest is seen ; the parasite fuses so completely
with the host-plasm that, according to Fischer, another
kind of plasmodium is produced.
CHYTRIDIINEAE 63
A careful study of the nuclear processes of these alleged
plasmodium-forming genera is greatly to be desired.
Sorus-formation. It is shown in Fig. 16 how a single
zoospore of Olpidiopsis without loss of individuality developes
into a single sporangium ; in an allied genus, Pseudolpidium,
either a single sporange or, as an alternative, a group of
sporanges or sorus may be produced. Sorus-formation is
the rule in Woronina.
Course of the Disease. The effects of infection by the
olpidians on their hosts constitute a disease, and the remarks
of E. J. Butler are of importance : " Cases were observed
in which the presence of the parasite did not interfere with
the normal life of the host, even to the extent that normal
sporangia and zoospores were formed, and it was only later
on when secondary sporangia were forming, that the parasite
gained the upper hand. . . . The zoospores of the parasite
often infected Saprolegnia zoospores during their first
encystment without checking the process of diplanetary
formation of secondary zoospores, though whether the
latter developed into a mycelium was not ascertained."
With the aid of a pocket-lens Cornu was able to separate
Saprolegnia-filaments in which were older parasites, but
the microscope was required to detect their earlier stages.
When the parasites first become visible under the micro-
scope they look like condensed portions of the host's plasm,
Fig. 15, A ; a little later they become more definite, B ;
later still, as at (7, they are large, well-defined, and some
64 PROTESTS AND DISEASE
contain bright globules. In this stage in Cornu's drawing
they look exactly like bodies from the cysts in a case of
cystic disease of the human urinary tract examined by
myself (1892) in the fresh unstained condition. These
bodies are termed " psorosperms " by some English patho-
logists, see Chapter X.
Olpidiopsis saprolegniae 1 produces two kinds of sporangia,
smooth- walled and prickle-walled, Fig. 15, D and E. Fischer's
description of the zoospores differs from Cornu's, as shown
at B and E respectively. Zoospores from prickle- sporangia
are said to be double the size of those from the smooth.
Fischer described an alternation of generations, the zoospores
from the smooth sporanges growing into prickle- sporangia
and vice versa. In Fig. 15, E, is shown the mode of formation
of sporoducts by the prickle-generation. The contained
plasm of the duct-process like the rest of the parasite sub-
divides into zoospores.
Cornu observed that the zoospores have a jerky move-
ment for a short time and that they disintegrate rapidly if
they do not succeed in finding a host. He also comments
on the resemblance of the plasm of Olpidium to that of the
Mycetozoa.
Fischer described the protoplasmic motion that occurs
in the parasites as they break up into spores ; it would
appear to be similar to that I described in molluscum bodies
in 1895. Fischer states that countless spores are evacuated
1 Differential features of Olpidium and Olpidiopsis are given on p. 61.
CHYTRIDIINEAE 65
in the course of an hour and that many remain in the
sporangia and perish. Thus in disease caused by parasites
akin to Chytridians we may find extensive areas of necrosis
composed of dead parasites.
Olpidium brassicae. This parasite attacks seedling cab-
bages causing damage which resembles that due to Pyihium
and which is included by gardeners under the name of
" damping off." The sporanges have sporoducts resembling
those of O. saprolegniae. Zoospores are uniciliate. Multiple
infection occurs.
Olpidium viciae. Kusano described conjugation of zoo-
spores in 1912. The zoospores develope into ordinary
sporangia, the zygotes into resting spores ; later findings
(1920) in a Synchytrium accord with this observation (Fig. 22).
Nuclear Processes in Olpidians. The development and
sexuality of some species of Olpidiopsis have been examined
by J. T. Barrett. The zoospores are bi-flagellate, Fig. 16,
a, b. The sexual process is by zygospore, usually in the form
of the prickle-sporangium of Cornu, but occasionally sporangia
are smooth.
When first liberated the zoospores swim actively for
from 2 to 5 minutes. They then become attached to the
slide and a rocking motion begins, the flagella becoming
shorter. After 7 to 10 minutes they cease to move for a
space of 5 to 20 minutes and one or two contractile vacuoles
appear in them and a second period of movement begins.
This sequence of events has been compared to the diplanetism
5
66
PROTESTS AND DISEASE
seen in Saprolegnia. The point of attachment of the flagellum
is hard to see.
Only a small percentage of zoospores effect an entry
Hi\
FIG. 16. NUCLEAR PROCESSES IN OLPIDIOPSIS. a, zoospores of 0. Sapro-
legniae ; b, the same of O. vexans, the lower one stained ; c, early
stage, non-sexual ; d, nuclear division ; e, early sporangium, resting
nuclei and internal vacuole ; /, sporangium, separate zoospores
formed ; g, zygospore, contents of antheridium passing into oogonium ;
h, the same stained ; i, ripe oospore. After J. T. Barrett.
into a host. Entry is as shown in Fig. 15, G to /. The
parasite at first contains but few granules, these grow and
coalesce into oil-like drops, which are replaced by vacuoles
at maturity when exit tubes are formed.
CHYTEIDIINEAE 67
The nuclei divide simultaneously by karyokinesis,
Fig. 16, d. Sexual stages were obtained by supplying
fresh food (ant larvae) to old cultures of Saprolegnia. The
sex-cells especially in O. saprolegniae and 0. luxurians are
easily distinguished from the vegetative cells by their
vacuolated coarsely granular plasm. All the contents of
the antheridium pass into the oogonium, Fig. 16, g and Ti,
from one to several hours being required. The nuclei of
the antheridium are small and in an active state, those of
the oogonium are large and resting. The ripe oogonium,
Fig. 16, i 9 has a thick endospore, inside this a finely granular
layer containing the nuclei, inside this again a coarsely
granular layer, and in the middle a large oil- drop, as in the
zygospore of Polyphagus.
The staining reactions of the nuclei of the zygote vary
at different stages.
Barrett did not see amoeboid changes in, nor fusions of,
the larger non-sexual parasites ; nor could he confirm
Fischer's view about an alternation of generations.
Sphaerita endogena. This parasite was discovered in
a culture of Euglena viridis by Dangeard, who also described
another chytridian, Nudeophaga amoebae, considered below
in Chapter X. For biology the value of these two genera
consists in the light they shed on processes previously
supposed to be modes of reproduction in protozoa and
which are now known to be instances of parasitism.
Sphaerita grows in the cytoplasm of its host, the nucleus
68 PROTISTS AND DISEASE
of the host-cell remaining unchanged. The nucleus of the
parasite consists at first of nucleolus, nuclear cavity, and
membrane.
Later the chromatin is arranged in groups of granules,
six granules in two rows appear to represent a primitive
mitosis.
A stage with many definite nuclei is followed by sub-
division into spores, liberated as bi-flagellate zoospores by
rupture of the host-cell. Dangeard also found a series of
stages that he was in doubt whether to attribute to Sphaerita
or to some other chytridian. No prickle cells (resting
sporanges) are described. Being devoid of mycelium
Sphaerita belongs to the Myxochytridinae and it differs
from Olpidium sufficiently to constitute a separate genus.
Chatton and Brodsky found a Sphaerita with the nucleus
situated eccentrically, and Dobell found a Sphaerita in
Endolimax nana, an amoeba parasitic in the human intestine.
4. Synchytriaceae. This order of the Chytridiineae is
distinguished by the prominence and regularity of sorus-
formation in the life-cycle. In some species, e.g. S. taraxaci,
this segmentation occurs within the original capsule of the
parasite ; in others, e.g. S. succisae, the parasite leaves its
capsule, Fig. 19, (7, before subdividing into sporanges.
Synchytrians are frequent parasites of a great number
of flowering plants. Some are limited to one species of
host, whilst others have a wider choice : thus S. aureum
has been stated to have been found on 180 different host-
CHYTRIDIINEAE 69
plants. Rytz concluded that this species has but few chief
hosts, but in favouring weather it infects other plants.
In marshy land near Berne the creeping loosestrife (Lysi-
machia nummularid) was the chief host ; in the Bernese
Oberland it was Saxifraga aizoides. Some species of
Synchytrium are of economic importance from their infecting
food-plants ; the potato, the cabbage and the strawberry.
Schroeter states that their occurrence is often very
regional, infected plants being abundant in one district,
whilst the same kind of plant in other similar regions is free.
Dampness of the soil favours them : in a low-lying part of
a meadow he found many infected scabious plants, but in
higher parts of the same meadow the scabious was free
from infection. Rytz states that Synchytrium alpimim,
parasitic in Viola biflora, is very common in Switzerland
up to 2400 metres, far above the tree limit.
Many Synchytrians are coloured; yellow, orange, and
red being common. They owe their colours to lipochromes.
Tn the spirit in which infected leaves are kept drops of
coloured oil may collect at the bottom of the containing
vessel.
Their effects on the host-plants vary. Often they are
not very damaging, causing only a nodular thickening of
the edges of leaves, which are rolled inw r ards. With the
naked eye sometimes, always with the aid of a pocket-lens,
the coloured or pearly points can be seen on leaf or stem or
both. They are sometimes obscured by hypertrophy or
70 PROTISTS AND DISEASE
proliferation of the cells around those that harbour para-
sites : small galls, Fig. 18, G, are thus produced. In the
common potentil this hypertrophy takes the form of hair-
cells. In the potato S. endobioticum causes warty cancer-
like tumours. Some kinds of potato are immune, but it
is not clear in what this immunity consists.
The Life-cycle of Synchytrians. The life-C3^cle of
Synchytrians varies in different species. In some, such as
S. anemones and 8. mercurialis, only resting-cells are
formed.
These are dormant all winter in the decaying remains
of the host-plant and germinate in spring, their zoospores
entering epidermis cells of young plants. From their
condensed life-cycle de Bary named these Pycnochytria.
They always pass through a soral stage in germinating.
The remainder, or Eusynchytria, have a double cycle, like
many Sporozoa. In suitable weather a series of generations
follow one another before the resting cells are formed. The
Eusynchytria again fall into two groups : in one group,
which may, perhaps, be named Pleochytria, and which
includes S. stellariae and S. oenotkerae (evening primrose) a
sorus is formed in both parts of the cycle : in the other
group the sorus is omitted from the germination of the
resting cell. To this latter group belong S. taraxaci, S.
siiccisae (scabious), and 8. endobioticum, &c.
8. aureum belongs to the pycno-group, having one
brood of swarm-spores in the spring of each year. One
CHYTRIDIINEAE
71
pycnochytrian, 8. Wurthii, is peculiar in having several
broods annually.
There is a wide range of nuclear form and mode of
division in different Synchytrians. Stevens reminds us
that larger nuclei are found in these fungi than in any other
plants : the synchytrian nucleus often measures 35/ji, the
nucleolus lip. in diameter ; an average vegetative nucleus
a ^ b ^^^ c ^0^~ d -^^ f
FIG. 17. SYNCHYTRIUM STELLARIAE, FROM STELLARIA MEDIA. GERMI-
NATION OF RESTING CELL IN WATER AFTER IT HAD BEEN KEPT DRY
ALL WINTER, a, more than half the protoplasm has streamed out
of its capsule ; 6, 4 hours after a ; c, 7 days later, the sorus had been
subdivided into sporangia for 5 days ; d, sorus completed, sporangia
separating ; e-g, formation of zoospores ; 2 hours between e and / ;
45 minutes between / and g. a-d X 145, e-g X 375. After de Bary.
in plants being from 5/x, to 9p. The host-cell increases from
ISP to 100 p.
We may now consider a few details of the life-cycle in
this genus. First, as is desirable in all study of protists,
we may consider changes as seen in the living organism.
An account of the germination of the resting cell of
8. Stdlariae as seen in the living state has been left us by
de Bary.
72 PROTESTS AND DISEASE
The ripe resting cell is enveloped in the remains of the
host-cell externally, and internally by its proper capsule
consisting of two layers, exospore and endospore. In
germination the endospore bulges at one small area very
much as happens in the germinating oospore of Cystopus,
Fig. 8. The leisured rate of the process as depicted by
de Bary is noteworthy. The first three stages shown in
Fig. 17 occupied seven days.
The dark granules seen in Fig. 17, /, are oil-drops, as
also are the dark spots in the zoospores. The redistribution
of fat plays an important part in the reproductive processes
of these parasitic fungi.
Of the eusynchytrian, 8. succisae, an account has been
given by Schroeter, some of whose illustrations are suggested
in Fig. 18.
Schroeter found synchytrians so easy to study that he
almost apologises for the lightness of his task. He found it
easy to infect young leaves, Fig. 18, A, by placing on them
water containing zoospores. The plant-tumour or gall, G,
deserves careful scrutiny : the shrunken capsule of a summer
or soral sporange lies in the middle ; projecting above it
are hypertrophied host-cells ; beneath it and at its sides
are infected host-cells containing resting- spores in course
of development. In view of what follows we may regard
the resting stage as being developed from zygotes, i.e. paired
zoospores.
Recognition of synchytrian infection in wild plants may
CHYTRIDIINEAE
73
be of great importance ; thus, for example, infection of the
potato by S. endobioticum has been found to be associated
with infection of hedge-row plants, the woody and the
black nightshades, Sotanum dulcamara and S. nigrum
respectively.
At this point we can profitably select information on
B r/^\\ v.; -^=rr- ii^ij'^r^ir^'^.c^ 1 f ^i rni li ft G
FIG. 18. DETAILS OF SYNCH YTRIANS. A, young parasites in the epidermis
of a scabious plant ; B, a ripe parasite in its natural site ; C, the
typical germination of a synchytrian : the sorus formed ; D, two
segments of the sorus of S. globosum (of the dog-violet), showing
interstitial substance ; E, a sporangium of S. succisae ; F, four
zoospores ; G, a gall, showing the capsule of the original parasite and,
in the cells, stages of resting-spores. After Schroeter, reduced to f .
that important parasite Synchytrium endobioticum, the cause
of wart disease or black scab of the potato. Taking first
information given in Leaflet No. 105 issued by the Board of
.Agriculture and Fisheries : " The young warts may easily
be seen in the eyes of the tubers. . . . They increase in size
and subsequently become irregular excrescences, which
74 PROTESTS AND DISEASE
often run together forming large masses. In certain varieties
(e.g. Arran Chief) all resemblance to a normal tuber may be
lost, the entire tuber being transformed to a coralloid mass.
The warts are at first white, but as they become old they
begin to turn black and finally form a putrid mass from
which dark brown liquid exudes."
The parasite was first described in 1896 by Schilbertzky
in Hungary as a chytridian. John Percival, Reading,
recognised it as a synchytrian and named it as above.
A monograph by Dr. K. M. Curtis was published in
1921. It is a record of a very thorough biological study :
from it a scheme of the life of the organism can be con-
structed as is done for Sporozoa and other protists, Fig. 19.
Curtis found that zoospores can live nearly a week in
an intact sporangium of S. endobioticum, if the sorus is not
ruptured. If water is added the sporangia burst and the
zoospores rush out. They are very active moving to and
fro for from 10 to 20 minutes. In 30 to 40 minutes move-
ment ceases, and unless they are in contact with a suitable
host-cell they disintegrate.
Unripe sporangia need more time to discharge and the
zoospores are sluggish at first, and some die either in the
sporangium or near it. Living zoospores, Fig. 20, a, are
1 '5^ long and have a bright spot, the nucleus, at the anterior
end.
It seems that zoospores from the same sporangium do
not pair. Before conjugation can occur a preparatory
CHYTRIDIINEAE
75
FIG. 19. DIAGRAM OF THE LIFE-CYCLE OF A FUNGUS, SYNCH YTRIUM
ENDOBIOTICUM. A, parasite with remains of flagellum still present
entering an epidermal cell ; B, parasite much larger with large nucleus
and granular plasm at the surface of and above the nucleus, the
lateral host-cells hypertrophied and projecting as the " rosette " ;
C, sorus-formation, more than half the parasite has passed out from
its original cell-wall ; D, first mitosis of sorus ; E, sorus completely
subdivided into sporangia ; F, single ripe sporangium, zoospores
escaping, two forming a zygote at z ; M, zygote entering epiderm
cell, its two flagella showing as remnants ; N, parasite grown larger
lies on the deep side of the host-cell nucleus, which, with those of
adjacent cells, is in mitosis ; O, parasite still larger with granules in
its plasm ; P, definite chromidia in plasm of parasite, ceUs of host-
plant deep to it in mitosis ; Q, parasite full-grown with large nuclear
cavity and nucleolus at one side of it ; rp indicates a resting period of
2J months ; R, ripe resting-sporangium germinating, zoospores
escaping. Based on K. M. Curtis's descriptions.
76 PROTISTS AND DISEASE
pause is required between the formation of zoospores in
two separate sporangia and their discharge. The conjuga-
tion is selective isogamy, the chief details of which are shown
in Fig. 22, which also shows the relation of the parasite to
the host-cell, and its development to a chromidial resting-
cell or sporangium in which zoospores are formed.
Miss Curtis found that the maturation-period of the
resting- sporangium from the time of the formation of the
outer membrane was 2| months. Rain-water produced the
quickest germination. A very significant point regarding
the maturation of the resting sporangium of 8. endobioticum
is mentioned. E. S. Salmon (1908) as the result of a series
of infection experiments concluded that resting sporangia,
after exposure for 1| hours to a temperature ranging from
5 C. to 6 C., could dispense with the winter dormancy
and germinate at once. In Nature the sporangia ripen in
the host-tissue ; when this decays they are liberated.
Shortly before maturation the sporangium enlarges
rapidly, sometimes doubling its diameter. At this stage
the two outer membranes are soft and the innermost is
hyaline. This distention gives the zoospores more room
and their flagella attain their full length. Rupture of the
sporangium is by a slit. The zoospores are in active move-
ment before the rupture, and at suitable temperatures,
12 C. to 14 C., continue to move for 2 hours. Zoospores
from resting sporangia measure 2/x, one-third larger than
those from the sorus.
CHYTRIDIINEAE 77
Curtis explains short flagella such as those in Fig. 18, F,
as being due to immaturity.
Entry into the host-cell is similar to that of the zygote,
Fig. 22, b. Having entered, the parasite first approaches,
Fig. 20, fr, then sinks below the host-nucleus as at c.
Growing rapidly the nucleolus discharges chromatic material
at intervals into the nuclear cavity and some of it enters
the cytoplasm. The chief features of what has been recorded
of the synchytrian nucleus is given in the next Chapter.
Referring again to Fig. 19, D, and A 7 , we note that the
parasite seems to be able to excite just such cell-divisions
in the host-tissue as serve its changing needs. Only actively
dividing regions of the host-plant are attacked. At B in
Fig. 19 the lateral cells project to form a cup ; this serves
to catch rain for the hatching of zoospores shown at F.
At D host-cells deep to the parasite are in mitosis causing
a tension towards the surface where the summer sporanges
are to be formed : at N the surface cells are dividing, placing
the winter sporange deeper in the tissue of the host to
mature thus protected.
CHAPTER IV
THE SYNCHYTRIAN NUCLEUS
SOME protists have two modes of reproduction, firstly by
mitotic cell-division, and secondly by the way of a generative
chromidium, see Figs. 1 and 2. Both these modes are
found in the genus Synchytrium.
A great variety of nuclear processes has already been
made known by different observers, and the bearing these
have on general cytology and pathology makes their close
study necessary.
F. L. and A. C. Stevens commented on the work of
Dangeard and of Rosen on 8. Taraxaci in a note to the
effect that current theories of the nucleus would suffer
violence if the conditions reported by these authors really
existed. Dangeard had described as an occasional occur-
rence a direct division of the nucleus by inflexion of the
nuclear membrane. Rosen found that in the primary
nucleus the chromatin forms a spireme, and the nucleolus
divides, the halves migrating to form daughter nuclei,
thus completing a nuclear division in the spireme condition
without the aid of the usual achromatic structures. The
subsequent successive divisions Rosen found to assume more
and more the character of an ordinary mitosis. The Stevenses
78
THE SYNCHYTRIAN NUCLEUS
79
gave an account of the first mitosis in the soral sporangium
of SyncJiytrium decipiens of Falcata comosa, the hog pea-nut,
an American plant.
Nuclear Divisions in the Sorus. The division of the
primary nucleus of S. decipiens is mitotic. The nuclear
i I
N-T5
E
FIG. 20. THE PRIMARY NUCLEUS OF SYNCHYTRIUM DECIPIENS. A,
Parasite in an epidermal cell ; B, nucleolus and part of nuclear
membrane, masses of chromatin are emerging from one side of the
nucleolus ; C, spireme stage, nucleus surrounded by a chromidial
zone ; D, spindle forming in middle ; E, mitosis nearing metaphase.
After F. L. and A. C. Stevens.
membrane being gradually dissolved (from the outside the
authors thought), becomes gelatinous and stains more
deeply. The nucleolus from one side discharges its chromatin
in large lumps, Fig. 20, B, and these appear to break up
80 PROTISTS AND DISEASE
into globules and accumulate in the gelatinous nuclear
envelope. Finally the nucleolus, save for a few globules,
entirely disappears leaving the nucleus as shown in C,
which the authors regard as the typical spireme of the
8. decipiens. The nucleus shrinks as the spireme threads
coalesce to meet in the middle, D. Finally an intranuclear
spindle appears, the chromosomes, about three in number,
at first forming a cap at each end. The spindle becomes
constricted at its middle, E, and the nucleus divides.
If we compare the nuclear processes just described
with those Wager met with in Polypkagus, Fig. 14, it is
obvious that the accumulation of granules about the nucleus
is a chromidium.
Other phenomena observed in 8. fulgens, papillatum,
and decipiens by F. L. Stevens are detailed in Chapter V.
Sorus-formation in S. endobioticum. The nucleolus
having increased greatly in size lies eccentrically in the
nuclear cavity and discharges chromatic granules along
linin strands into the cytoplasm, which thus becomes highly
chromatic, and a fine cell-membrane is secreted. Granules
collect at the upper part of the membrane and over the
upper end of the nucleus, Fig. 21, c. The membrane is
then dissolved at a pore and first part of the cytoplasm,
next more plasm and part of the nucleus, and finally the
rest pass out of the membrane into the upper half of the
host-cell, d. The nucleus now shows linin-threads, e.
Soon an intranuclear spindle with 5 chromosomes is formed
THE SYNCHYTRIAN NUCLEUS
81
and the first division occurs, /. Successive simultaneous
mitotic divisions follow till the sorus subdivides into
sporangia, g, containing a great number of small nuclei.
The young zoospores are at first close -packed but, water
FIG. 21. SYNCH YTBIUM ENDOBIOTICUM, AGAMIC STAGES, a, zoospores,
living state ; 6, young parasite nearing host's nucleus ; c, full-grown
parasite ready to develope into a sorus, pyramidal heaping of granules ;
d, a stage in formation of the sorus, the nucleus beginning to pass
through the opening in the capsule ; e, primary soral nucleus, late
prophase ; /, the same metaphase, spindle with 5 chromosomes ;
g, early stage of segmentation of sorus ; h, zoospores nearly full-
grown, the stands joining them become flagella later. After K. M.
Curtis.
being absorbed, they become more loosely arranged and
are joined by fine strands which become the flagella entering
each zoospore at the point where the blepharoplast is seen.
6
82 PROTISTS AND DISEASE
In the agamic stages S. endobioticum contains a good
deal of chromidial material derived from the nucleus, but
no definite chromidial zone enveloping the nucleus such as
Stevens found in 8. decipiens is produced. The passage of
chromatin into the nucleus by a series of discharges rather
than in a continuous stream as appears to have been
observed in other species is perhaps a variable phenomenon :
the difference is that in one case there is a series of unipolar
mitoses, in the other a stream of chromidial elements.
Possibly equable experimental conditions determined the
regularity of the various stages in 8. endobioticum.
The Gametic Stages of S. endobioticum. The complete
examination of this one species that we owe to Dr. Curtis
calls for comparison with what has been found in other
species and for reflection upon the facts.
There is little doubt that the formation of zygotes by
conjugation of zoospores will prove to be general in
Synchytrium.
In Pycnochytria (in de Bary's sense) only the gametic
part of the life-cycle will probably be found, and it will be
interesting in this group, and in that division of the Eusyn-
chytria which produce a sorus from the resting-cell (S.
stellariae &c.) to see what exactly are the nuclear and
chromidial processes in the gametic sorus. Cells infected
by zygotes divide leaving the parasite in the deeper daughter
cell, Fig. 22, e. This division is repeated till the infected
cell lies under two or more layers of uninfected cells.
THE SYNCHYTRIAN NUCLEUS
83
FIG. 22. S. ENDOBIOTICUM, SEXUAL GENERATION, a, 4 stages of
syngamy, the lowest shows recession of the 2 flagella ; b, 5 stages in
penetration, the transverse line is the surface of a host-cell ; c, cell
with young zygote smaller than cell-nucleus ( X 400) ; d, the parasite
is larger and lies below the cell-nucleus ; e, division of host-cell
containing 5 parasites, the latter remain in the lower half of the cell ;
/, cell with large parasite now separated from the surface by previous
divisions of host-cell ; g, part of a parasite, it has its own capsule
and, outside that, a second derived from the host-cell, its nucleolus
has discharged chromatin into the cytoplasm, where chromidial
granules are seen, x 800 ; Ji, zoospores beginning to be formed from
chromidia, X 1650 ; i, j, further stages in zoospore-formation ; k,
zoospores x 780, living (left) and fixed and stained (right) ; I, zoo-
spore x 1650, nucleus, blepharoplast, and joining strand seen. After
K. M. Curtis.
The Gametic Nucleus. Fusion of the two gametic nuclei
is shown in four stages at a, and the part played by the
nucleus of the zygote during penetration of the host-cell
84 PROTISTS AND DISEASE
in five stages at b. The parasite's nucleus is at first a
" single chromatic globule lying free in the mass of the
cytoplasm." A nuclear space soon forms, c and d. Later
the nucleolus becomes the most prominent feature of the
nucleus, as at /, and from it strands of linin stretch to the
nuclear membrane.
In the parasite's cytoplasm are numerous chromatic
granules ; a feature which becomes more prominent later.
Continuous with the nucleus, is a mass of linin fringed with
points of chromatin (the " amoeboid body " of Percival) ;
the chromidial granules in the cytoplasm are now more
numerous and the parasite has secreted a capsule upon
which matter from the remains of the host-cell is being
deposited, g.
The Generative Chromidium. The chromidial granules
arise, Dr. Curtis states, by some six or seven intermittent
discharges from the nucleolus. They first accumulate in
estricted equidistant areas, Fig. 19, P, but afterwards
completely replace the cytoplasm, the remains of the nucleolus
then seems to be of no active service. The chromidial
sporangium is thus established. The granules of the
chromidium at first stain uniformly with iron-haematoxylin
and hence, as is explained below, the chromidium is at
first in the plasson state. The granules are the nodal
points of a fine reticulum and they soon show central chro-
matin granules with a clear space around them, and outside
a lightly staining zone, Fig. 22, h.
THE SYNCHYTRIAN NUCLEUS 85
At this stage some of the granules, now zoospore-origins,
or " primordia," show signs of subdivision. Later still the
plasm of the primordia becomes vacuolated and granules of
chromatin are expelled, i ; by this process the primordia
become equal and spherical and their chromatin is reduced
to a few granules, from which the single nucleus of the
zoospore is formed. The young zoospore's plasm first
becomes dense, then vacuolated, j. The nucleus in the
zoospore has a clear central area with chromatin granules
around it, k, and a chromatic strand stretches from it to
the blepharoplast at the opposite end of the body of the
zoospore.
A species of Synchytrium in a Thistle. For an oppor-
tunity of studying some aspects of the cytology of Synchy-
trium and of comparing it with such records as I have read
and with the structure of Plasmodiophora and Mycetozoa I
am indebted to the kindness of Professor V. H. Blackman
and Assistant Professor R. J. Tabor of the Imperial College
of Science and Technology.
The host-tissue was a thistle-leaf 1 which had been fixed
in 95 % alcohol. With a pocket-lens the parasites were
seen as brick-red points. Sections were cut for me by
Dr. Perkins and stained with H. and E. Some of the
results are shown in Fig. 23.
The walls of the host-cells are thick and stain deeply as
1 Not having been able to identify the species of either host or parasite in this
instance I refer to the parasite in what follows as the thistte-Synchytrium.
86 PKOTISTS AND DISEASE
also do the special capsules of the soral sporangia. Of the
latter some are somewhat shrunken by dehydration as
shown in Fig. 23, a.
In some sections clusters of three sori are found. It
will be noted that the cells around the sorus do not project
to form a rosette. The rigid nature of the host tissue
caused the parasitic elements to fall out of a number of the
sections so that a continuous series of sections of any one
element was not obtainable, still it is easy to recognise two
separate processes ; one the formation of sori, the other
the formation of single or direct sporangia in some of which
the zoospores are completely formed. In this thistle the
soral sporangia and the non-soral (here termed " direct ")
might belong to different species, though this would not
rob their minute structure of interest and meaning. The
earliest stages are not present : the youngest direct
sporangium met with is shown in Fig. 23, c, d, where three
nuclei are seen, all having relatively large nucleoli. The
nuclear membranes are merely surfaces of plasm bounding
sap-vacuoles in each of which a nucleolus lies eccentrically.
The nucleoli have the same general characters as those of
S. endobioticum. What looks like a vacuole in Fig. 23, e,
is really a blunt process like others which are seen in profile
in the same element, studded at their surface with granules,
the latter on the left side being continuous with the adjoining
part of the nuclear membrane. In 8. endobioticum the
nucleolus (according to Curtis) discharges chromatic matter
THE SYNCHYTRIAN NUCLEUS 87
intermittently to form chromidia in the reticulum, whereas
in this thistle- tSynchytrium the nucleolar substance has the
appearance of being converted continuously into a chromatic
reticulum in which separate chromatin granules are not
recognisable.
The next stage of the direct sporangium is that shown
in Fig. 23, /. The nucleoli are not yet wholly absorbed,
but the reticulum has changed, having become finely granular
and less deeply stained, and in every part definite equal
grains of chromatin are evenly distributed in the reticulum
of the developing sporangium. Stages between that just
described and the formation of separate zoospores, Fig. 23,
h, i, are not to be traced clearly in the sections of the thistle.
The zoospores are typical ; but in this case the wall of
the direct sporangium is much thinner than that of the
soral sporangia. Beside the intracellular parasites in the
thistle are larger intercellular bodies, stained purple and of
a texture resembling akaryote plasmodia. These structures
call for further examination.
The Nuclear Cavity. With regard to the nuclear cavities
Fig. 23, d, and /, they are obviously nothing more than
sap-vacuoles ; and in this relation it is of interest to recall
the view expressed in 1903 by A. A. Lawson, and supported
by careful cytological observations. Lawson concluded that
the nuclear cavity of the cells of the higher plants is only
a water- cavity similar to a cell-vacuole ; in other words
the nuclear membrane is a cytoplasmic structure.
88
PROTJSTS AND DISEASE
The three nucleoli seen in Fig. 23, d, have probably arisen
from the division of a single nucleolus and have become
separated by the formation from their own substance of
f
FIG. 23. DETAILS OF A SPECIES OF SYNCHYTRIUM IN A THISTLE-LEAF.
a, sorus subdivided into sporangia ; 6, a soral sporangium, zoospores
nearly formed ; c, early stage of direct sporangium ; d, part of c
more magnified showing three nucleoli ; e, a single nucleolus still
more magnified ; /, a stage later than d, a single nucleolus and grains
of chromatin in a finely granular plasm ; g, a stage later than /, proto-
plasm segmented prior to zoospore-formation ; h, direct sporangium ;
i, part of h more magnified, zoospores. Magnification : a, c, and h,
X 80 ; b, d, /, g, and *, X 1000 ; e, X 1500.
new reticular plasmodium. One of the nucleoli, the upper-
most in d, has a projection not quite separated from the rest.
Assuming that both the soral and the direct sporangia
of the thistle- Synchytrium belong to the same parasite, an
assumption that makes no difference in regard to the cyto-
logical points to be considered, we may compare some
THE SYNCHYTRIAN NUCLEUS 89
features of this infected thistle-leaf with those described by
Curtis in the potato.
Apart from the want of a " rosette " and there being no
evidence of cell-proliferation on part of the host-tissue,
the formation of the sorus and the character of the nuclei
in the nearly ripe soral sporangia is the same in the two
parasites.
Very different is the rest of the picture ; and yet the
character of the nucleoli, and the processes of chromidium-
formation show that the direct sporangium in this thistle-
Synchytrium corresponds with that sporangium of 8. endo-
bioticum that developes from a zygote.
Stages of the two may be compared as far as a very
partial examination of the thistle- Synchytrium allows. Fig.
23 is reproduced from the " Lancet," vol. ii. p. 495, 1921.
In the thistle- Synchytrium at a certain stage no separate
chromatin points are to be seen, so the term " plasson " is the
one I would suggest to describe the state of the sporangium
as shown in Fig. 23, d and e. It becomes chromidium
at the later stage, /. The terms plasson and chromidium
are used here as defined above, Chapter I, pp. 4-6.
The Synchytrian Nucleolus. The nucleolus is the
dominant cell-organ in Synchytrium ; from it are developed
the chromidia ; vegetative in the agamic, generative in the
gamic stages ; and in the former also the chromosomes and
spindle. The nucleolus is the centre of growth as well as of
reproduction in Synchytrium.
90 PROTISTS AND DISEASE
The synchytrian nucleolus is composed of living matter
with the least recognisable differentiation of structure and
of the greatest potential ; all cell-organs being formable by
it ; it is totipotential protoplasm ; plasson.
An instance is given in the next Chapter of a whole
synchytrian nucleolus expanding on all sides simultaneously
into a spreading mass, which infiltrates the cytoplasm. In
that and other similar cases the nucleolar expansion appears
to have replaced a primary and several subsequent mitoses,
smaller nuclei being formed from the expansion as bird's-eye
bodies.
In the direct sporangium of 8. endobioticum expansion
occurred by a series of what may be regarded as unipolar
mitoses ; in that of the thistle- Synchytrium by a gradual
and continuous expansion from the surface of the nucleolus.
To the original unexpanded form of plasson as seen in
the nucleolus the adjective pycno (Gr. = dense) may be
applied, the expanded state as seen in Fig. 23, d, being
designated chasmatoplasson (Gr. chasma an expanse).
If we imagine a degree of parasitism even more intimate
than is to be found in Synchytrium, we should expect to
find the parasites reduced in some stages of their existence
to the condition of the synchytrian nucleolus. In Chapters
VI and X it is shown that the causal parasites of molluscum
contagiosum, smallpox, syphilis, and cancer are reduced to
this state in their earlier stages.
CHAPTER V
" CANCER-BODIES " IN SYNCH YTRIUM AND IN SYPHILIS
Bird's-eye Nuclei in Synchytrium. In three species of
Synchytrium F. L. Stevens found nuclear structures the
nature of which, he stated in 1907, was far from clear:
FIG. 24. SOME NUCLEAR PROCESSES IN SYNCHYTRIUM DECIPIENS. a,
Irregular nucleolus extending into the cytoplasm by radial extensions ;
6, group of bird's-eye nuclear bodies with an aster ; c, cluster of
bird's-eye bodies such as are often seen in cancer ; d, bird's-eye body
with aster attached ; e, mitosis, metaphase ; /, mitosis, anaphase.
After F. L. Stevens. From the " Lancet."
' The structures were atypical, strikingly peculiar, and
quite without parallel in any plant or animal as yet de-
scribed." Some of these bodies are shown in Fig. 24, &, c, d.
The large nucleolus, Fig. 24, a, is continuous with the
91
92 PROTISTS AND DISEASE
cytoplasm by radial extensions across the remains of the
nuclear cavity. The latter is seen as in the direct sporangium
of the thistle- Synchytrium described at the end of Chapter IV
to be nothing more than a sap-vacuole. Stevens terms the
irregular body, Fig. 24, a, a nucleus, but there is no doubt
that it corresponds to the nucleolus of Fig. 20, B.
The nucleolar substance instead of growing into the
cytoplasm by intermittent mitotic discharges as in S. endo-
bioticum, or by continuous expansion as chasmatoplasson
in the thistle- Synchytrium, has become amoeboid and is
streaming on all sides into the cytoplasm.
Together with nuclei such as that just described Stevens
found homogeneous nuclear bodies, Fig. 24, 6, surrounded
by a clear space and bounded by a delimiting membrane.
Sometimes, as shown at c, they were met with in closely
packed groups. Stevens also found astral bodies either
near, as in 6, or attached to these nuclei, d.
The Bird's-eye Bodies of Cancer. The abovementioned
curious nuclei found by Stevens in .Synchytrium are nothing
more nor less than the homologues of the " cancer-bodies "
or bird's-eye bodies of human pathology. In 1892 and for
several years after that date they were claimed by some
pathologists to be the only true " protozoa " to be found in
cancer.
They are not peculiar to cancer, nor are they to be found
in their typical form in all cancers, though they are remark-
ably abundant in many.
CANCER-BODIES
93
Their appearance in many cancers, e.g. in the cancer of
the breast shown in Part III, Plate VII, is even more like
Ste vena's nuclei in Synchytrium than are those shown here
in Fig. 25.
As they are seen in cancers these bodies have been very
frequently described in pathological writings from 1892
onwards, but I have never seen so good a description of
them as that Stevens
wrote :
" Large homogene-
ous nuclear bodies
consisting of nucleoli
or chromatin, or both,
are scattered in the
protoplasm of the
parasite. They are
surrounded by a clear
sap-space which is
ordered by a definite
nuclear wall. In some cases no wall was discernible."
Stevens found asters associated with many of these
bodies as shown at b and d, which are copied from portions
of Stevens' s drawings of larger areas containing many such
elements, concerning which he writes : " They undoubtedly
do arise sometimes by successive divisions of the nuclei
arising from the primary division as described in 1903.
Stages showing 1, 2, and 4 spindles per cell prove this, but
FIG. 25. BIRD'S-EYE BODIES. Part of a
section of a cancer of the breast. After
F. B. Mallory, from Part IV.
94 PROTISTS AND DISEASE
if such were the prevalent mode stages between elements
like Fig. 24, d and the binucleate stage would be common,
and they are not ; I am led to consider the possibility of a
second mode of division of the primary nucleus consisting
of a simultaneous breaking of the one nucleus into many."
I think the puzzling bodies are nuclei usually originating
in a chromidium, as I saw it in the living state in syphilis.
The following account is copied from Part II, but was first
published in 1907. Before passing to this description I
would again refer to the nucleus of S. decipims, Fig. 24, a,
remembering that the nucleus there depicted corresponds
with the soral nucleus in 8. endobioticum, Fig. 21. We see
that, instead of dividing, the nucleolus of 8. decipiens as
seen by Stevens became plasmodial and was streaming
into the cytoplasm, where new nuclei were formed as they
are from generative chromidia. I have seen similar nuclei
or bird's-eye bodies form in molluscum corpuscles after
they have been in water for some days.
Living Bird's-eye Bodies in Syphilis. The production of
these bodies in living intracellular parasites in syphilis is
so important that I will insert the account almost as it
stands in Part II ; the observation was made long before
the introduction of rapidly acting arsenical compounds in
the treatment of syphilis.
The groups of oscillating granules which I saw associated
with the formation of bird's-eye bodies would probably be
equivalent to the asters Stevens described in Synchytrium.
" CANCER-BODIES " 95
I had for a long time desired to watch these bodies under
conditions similar to those that obtain during life, but so
great are the obstacles to such work in professional life, and
so reluctant is one to withhold treatment from a patient,
and so rapidly in syphilis are lesions usually removed by
treatment, that it was not until August 31, 1901, that I was
able to do this. Among my out-patients at the N.-W.
London Hospital was a man who had some obstinate
tertiary syphilitic lesions on the face and in the mouth that
resisted full doses of the biniodide of mercury and potassium,
which I had given to him by the mouth for several weeks.
These lesions were subsequently completely cured by intra-
muscular injections of sal-alembroth. I arranged for this
patient to attend at about 7 p.m. on the date mentioned,
and after wiping the surface of a warty lesion of the hard
palate with a dry sterilised swab I took a scraping with a
clean knife, not going sufficiently deeply to cause any
bleeding. The material thus obtained I mounted in its
own liquid exudation, covered it with a thin cover-glass,
and examined it on a Strieker's warm stage. With the
objects before me I made the graphic and written notes
which are reproduced in Fig. 26 and the accompanying
description.
What are the bodies ? They are certainly of kindred
nature to those I described in cancers in 1892, but it is to
be noted that on the warm stage these bodies from the
tertiary lesion exhibited what could only be vital processes.
PROTISTS AND DISEASE
o'
' * r\
$''
FIG. 26. BODIES OBSERVED IN A SCRAPING OF A TERTIARY SYPHILITIC
LESION. 1, An ordinary squamous epithelial cell devoid of move-
ment ; 2, a similar cell, but containing in optical section a granular
mass in which are three typical bird's-eye bodies, and at o' a group of
granules in lively oscillation ; 3, another epithelial cell, the nucleus
of which is not seen, and which contains two highly refracting inclu-
sions ; 4, a free body of similar optical characters to the inclusions
in 3 ; 5 and 6, structures resembling an epithelial cell in size, but
containing large globules of a bright greenish appearance, and at o
and o' groups of smaller globules in oscillation ; 7 and 8, small bodies
resembling parts of 5 and 6, lively oscillation in one, and oscillation
and a greenish nuclear body in the other ; 9, a large body, the pale
central mass of which is not shown, but globules and granules and a
few wavy lines are seen on the surface ; 10 and 11 are the same body,
10 as seen at 7.20 p.m., and 11 as seen at 10.45 p.m., when the prepara-
tion has cooled down. When first seen, there was a group of oscillating
granules, o, and a single greenish curved structure to the left of them ;
later, the preparation having cooled down, the oscillating granules
had disappeared, and the body seemed to have divided into two.
Seen by y 2 - in. oil-imm. objective. From Part II.
" CANCER-BODIES " 97
Each group of oscillating granules could only represent a
focus where a process equivalent to mitosis was going on.
The mass invading the epithelial cell shown in Fig. 26, 2,
contained three typical " bird's-eye bodies," and the cluster
of granules in violent oscillation at o' marked the spot where
another bird's-eye body was in process of formation. I
had previously concluded from histological study that
these bodies are thus formed, and this observation of the
living cells confirms my view. Bodies such as 5 and 6 are
met with in sarcoma and cancer as well as in syphilis. The
clear circles within them represent greenish globules, which
are formed in the same way as the bird's-eye bodies and the
oscillation at o, in these two bodies marked I do not doubt
the formation of new globules. The two smaller bodies,
7 and , as shown in the sketch, are not unlike leucocytes,
but in the living state their absolute identity in physical
characters with the larger bodies and their green colour 1
and oscillating granules distinguished them from leucocytes.
As to the bodies 10 and 11 the partial capsule at their upper
end is probably the remains of host-cells, and the evidence
detailed in the description strongly supports the view that
the curved greenish body near the group of oscillating
granules at o divided into two parts.
' ' Cells of endogenous origin. ' ' These nuclear structures
described by Stevens in Synchytfium, by many pathologists
1 A similar green colour is to be seen in the early intracellular stage of the parasites
of smallpox and in some of those of cancer, &c. It is also seen in the nuclei of human
epithelial cells when teased out in water, especially at the metaphase stage of mitosis.
98 PROTISTS AND DISEASE
including myself in cancer, and by myself in syphilis are
nothing more than Virchow's " cells of endogenous origin."
In 1851 Virchow summed up his observations thus : " A
portion of a large cell with granular contents, perhaps an
altered nucleus, the dimensions of which it has, becomes
homogeneous and clear like water. This portion has at
first a sharp and stout wall, which very soon by the addition
of fresh layers is thickened and becomes doubly-contoured,
in every way like a cartilage cell." The " granular contents "
of the foregoing description agrees with the appearance
shown in Fig. 26, 2. The " cells of endogenous origin " are
nuclei formed in parasites in the chromidial state, and they are
only temporary nuclei comparable, perhaps, to the tropho-
nuclei of Plasmodiophoraceae (Chapter VII). They are
occasionally seen to form in molluscum-bodies in water-
cultures, see Fig. 32. They do not represent a necessary
or invariable phase in molluscum, or in cancer, or in
Synchytrium ; but what may be termed an optional or
alternative phase.
CHAPTER VI
PLASSOMYXINEAE AND MOLLUSCUM CONTAGIOSUM :
MICROHENADS
THE term Plassomyxineae first used last year to designate
a group of pathogenic organisms, of which the casual parasite
of Molluscum contagiosum is the most easily studied, I
have defined as follows : diagnosis : Plassomyxineae, nomen
novum, applicandum quaedam ad protista parasitica et patho-
genica, generi Syndiytrio affinia, quae interdum in statu
plasson dicto sunt.
The name first given to any group of organisms, if it is
not based on misconception and hence misleading, must
stand as the name of the group in question. Now in using
the name Plassomyxineae, I am well aware that the term
Chlamydozoa has been previously applied to the molluscum
body and kindred structures. Let us trace this idea to its
source. It had been found that molluscum bodies resist the
action of strong acids and alkalies, &c., and it was inferred
that they could not therefore be anything but colloid.
The matter was conscientiously examined by L. Pfeiffer,
who compared the behaviour of Coccidia with that of the
99
100 PROTISTS AND DISEASE
molluscum body when treated by the same chemical reagents.
He found that coccidia were altered in appearance, but not
the molluscum. His conclusion was that the molluscum
body could not be a Coccidium, but that within the opaque
colloid covering of the molluscum body there was concealed
a parasite. This same view was adopted later by von
Prowazek with the addition that he identified the parasite
with some alleged minute granules in the middle of the
body, and he made the name Chlamydozoa for the group to
which the molluscum body belongs.
Now, seeing that except for a thin cortex the middle of
the body is like the rest, and that the parasites appear from
what follows to be most closely related to the genus Synchy-
trium, and so not protozoa at all. Prowazek's name is based
on misconception ; it is misleading, and should be replaced
by some more appropriate term.
Plassomyxa contagiosa. This name I have made to
apply to the causal parasite of molluscum contagiosum, and
seeing that some of its phases are easily studied in the living
state, the behaviour of the organism in water-cultures must
be given in some detail although they have already been
considered to some extent in Part IV.
Fortunately, the bodies characteristic of this disease in
the human subject when full-grown are relatively large,
Fig. 27, and firm of texture, and hence it is easy to watch
what happens to them when they are placed in surroundings
that make it possible for them to show that they are living
PLASSOMYXINEAE
things ; that is when we place them suitably in water, thus
using the experimental method.
Those observers who have studied lesions in their earliest
stages have found that the first site of the parasite is inside
the host-nucleus, and its escape into the cytoplasm has been
seen. Some subsequent
stages are shown below ' ,v
in Fig. 30.
Cultures. When we
are planning experiments
to decide whether any
object is alive we must
first consider the con-
ditions in which it is
found in nature.
The earliest stages of
Plassomyxa contaqiosa as ^ ^
FIG. 27. MOLLUSCTJM BODIES AND SQUA-
seen in sections of the MOUS EPITHELIAL CELLS. From a teas-
ing of a freshly excised nodule smeared
on a slide and fixed with perchloride
of mercury solution and mounted in
glycerine and water. Drawing eye-piece.
X 400 diams. From Part IV.
tumour are found inside
other cells, hence in anae-
robic conditions : the ripe
parasites on the contrary
are extruded from the body and their subsequent develop-
ment is most likely to be both aerobic and aquatic, the
latter probability being supported by the observation that
the disease is sometimes contracted in Turkish baths.
Aerobic water-cultures are thus indicated. Seeing that we
102 PROTISTS AND DISEASE
are dealing with an obligatory parasite only a certain limited
number of stages are to be expected in such cultures.
Considered as isolated phenomena the subjoined facts are
evidence of vitality in molluscum bodies : taken together
they either prove this vitality or they prove the microscope
to be useless for the study of protistic life. Personal practical
work of the simplest kind is required for any one to witness
the vital phenomena.
I
B
FIG. 28. A METHOD OF WATER CULTURE. A, the material to be'cultivated
is heaped in the middle of a watch-glass and water, but not enough
to cover the material, has been added drop by drop ; - B, after teasing
in a drop of water on a slide, a particle or drop of the material in A
is covered and examined microscopically, then the preparation is
inverted over a watch-glass containing water and put between Petri
dishes for re-examination later.
The culture must be kept at room temperature, because
incubation favours the growth of bacteria, which, when
abundant, kill the specific parasites. Occasionally a culture
apparently free from bacteria is obtained, but usually
bacteria are present ; in moderate number they do not
prevent vital changes from occurring.
It is important to make clear drawings of objects at the
PLASSOMYXINEAE 103
time they appear under the microscope, and it assists the
eye, if the main features of each stationary part are traced
by means of a drawing eye-piece or other similar optical
instrument.
Enumeration and Details of Vital Changes. Some vital
changes which I have already observed are shown in
Fig. 29 ; they are : 1, streaming of protoplasm with,
2, subdivision by budding ; 3, formation of a supporting
framework or of protective capsules ; 4, formation of
bird's-eye bodies ; 5, vacuolation with oscillation of granules :
6, formation of active flagellate or spirillar bodies.
i. Streaming. The reality of the phenomenon being
proved by facts recorded below a few details may be
added. Fig. 29, a shows the aspect of a corpuscle just
before streaming begins ; its texture becomes more granular :
this is succeeded by a disappearance of granules from either
part of, as at b, or throughout a corpuscle, as at c, e, and /.
The fresh corpuscle often presents indications of being
segmented, and a regular segmentation is sometimes seen
in water cultures ; in one such I found the rotary motion
affected one only of the segments, Fig. 29, d.
There are no separate granules to be seen in the moving
substance, which must be composed of extremely minute
elements, but large granules are sometimes seen on the
surface of the flowing part of a corpuscle, such granules I
have observed to be carried round one segment of bodies
such as that shown in Fig. 29, c.
104
PROTISTS AND DISEASE
2. Budding. From some of the bodies with streaming
protoplasm part of this can be seen to protrude as in
Fig. 29, /; and in the neighbourhood are smaller spheres
FIG. 29. VARIOUS ACTIVE PHASES OF PLASSOMYXA CONTAGIOSA. a,
molluscum body unchanged save that the cortex is more definite
and the granules are larger than in the fresh state ; 6, a clear area
has formed and in it the protoplasm is circulating ; c, an internal
framework continuous with the cortex has formed and the whole of
the protoplasm is circulating ; d, a capsule has formed and within it
the protoplasm is subdivided into segments, in one of which only the
protoplasm is circulating ; e, a spherical capsule has formed, the
protoplasm is circulating and is in part protruded beyond the cortex ;
/, the whole protoplasm is circulating and a small protrusion is present,
and there are three separate subdivisions with circulating proto-
plasm, one vacuolated, another with a clear outer zone, and, to the
right, three subdivisions as they appear when they come to rest clear
and refracting ; g, a body in a surface view of which five buds are
seen in process of formation ; Ji, a body in which a nucleus-like
structure has formed ; i, a body with vacuolated protoplasm, the
intervening granules in Brownian movement ; j, body with violent
agitation of protoplasm ; k, flagellated body with agitated granules
at its expanded end. d, /, and g, X 800 ; the rest X 500.
with streaming ; in some of the latter there is a bright
outer zone with no streaming ; some of the small streaming
spheres have a vacuole.
PLASSOMYXINEAE 105
All three kinds when they are observed to come to rest
assume a uniform refracting appearance and have a green
tint. Several times I have watched protrusions of streaming
protoplasm such as are shown in Fig. 29, / and g, having in
contact with them a small separate sphere of streaming
protoplasm ; and this sphere has, as if by the rotation of
its substance, moved slowly from its first position. Though
I have not watched the first formation and the actual
separation of one of the small spheres I have no doubt
these arise as buds from the molluscum bodies.
3. Doubly Contoured Capsules. These are rare in fresh
material, but many develop in water cultures, Fig. 29, e.
They seem to be formed as a defence against bacteria : I
have seen many with bacteria on the outside of the capsule
but never inside.
4. Internal Framework. Irregular processes extending
inwards may be formed apparently in the spaces between
the segments of a corpuscle. They are sometimes regular
and anastomose to form a net, Fig. 29, c ; or the framework
may be scanty as at /. When a capsule is secreted the
framework is not formed, and vice versa.
5. Nucleus-like Bodies. These are not present in the
fresh corpuscle. Granules appear in an area where a nucleus
or bird's-eye body is to be formed. Oscillating motion may
be seen among the granules as the nucleus appears in a
clear space bounded by a membrane. This stage represents
in my opinion a low state of vitality of the molluscum body.
106 PROTISTS AND DISEASE
6. Vacuoles. These I have seen once as sketched in
Fig. 29, i. The granules between the vacuoles were in a
state of oscillation or Brownian movement. I have seen
a similar appearance in a sclerotium of Badhamia utricularis
after it had been 12 hours in water.
7. Flagellate Bodies. This striking feature I have only
once observed in a culture on the fourth day. The material
was from abundant lesions, some of which I heaped up in
the hollow of one of the cupped slides for hanging-drop
preparations, and placed in a moist chamber as shown in
Fig. 28. The result I described in the Centralblatt fur
Bakteriologie, 1895, vol. i. p. 245.
The description, slightly condensed, runs
" The most remarkable appearance consists in the
presence of a great number of actively-moving flagellate
bodies. They have a roundish head of the size of a red
blood corpuscle, and a single powerful flagellum, and under
a one-twelfth immersion lens were easily seen and un-
mistakable ; many passed across the microscopic field and
then escaped from sight. Many of the molluscum bodies
were unchanged ; of others, but a thin shell remained ;
still others had apparently undergone a liquefaction in their
central part, and in this area were numerous highly-refracting
oscillating granules."
I may add that in what I called the " heads " of the
motile bodies Fig. 29, Jc, there were moving granules quite
like those in the molluscum bodies. The " heads " may be
PLASSOMYXINEAE 107
only residual, the flagellum becoming free as a spirochaete
or spirillum.
This state of reproduction I regard as the acme of vitality
in the parasite, the streaming state with budding coming
next.
Reaction to Iodine-Sulphuric Acid Mixture. -In a water-
culture of some molluscum lesions with which Dr. Ernest
Dore kindly supplied me last year I tested for cellulose
some of the bodies in which a framework had formed, by
adding a few drops of a mixture of one part of iodine solution
to two parts of sulphuric acid. Parts of the previously
colourless framework changed to a greenish blue colour: as
much reaction as I have ever found in moulds, mildews, &c.
With the same reagent the previously unchanged molluscum
bodies became a deep purple, which lasted a few days ; the
epithelial cells became pale yellow and swelled to oval form.
Some Synchytrium taraxaci was treated in the same way,
and I found its capsules were not stained at all ; the
sporangial contents became dark green. For the S. taraxaci
I am indebted to Mr. J. Ramsbottom.
Not a Coccidium. Many have tried to identify the
molluscum body with the familiar genus Coccidium. That
attempt has failed and worse than failed ; it has delayed the
recognition of the real nature of the parasite.
Only by purely objective study can we know the charac-
teristics of an organism, and having ascertained them with
minute care we must, if necessary, make a new group in
108 PROTISTS AND DISEASE
classification. The group to which the causal parasite of
molluscum belongs has not as yet, perhaps, been adequately
introduced to cryptogamic botanists.
The Molluscum Body is not a Symbiotic Cell. Arguing
from the fact that a 1 in 10,000 suspension of a ground-up
molluscum tumour gives a virulent filtrate, and that when
stained by Giemsa's method the molluscum body shows a
certain minute structure M. Borrel concludes that this body
is the result of symbiosis between an invisible microbe and
an epidermal cell. The observations recorded above of the
behaviour of molluscum bodies in water- cultures negative
this idea.
Microhenads. The word microhenad I suggest as the
designation for the phase in which the filtrable micro-
organisms are at the time they can be pressed or aspirated
through a filter that arrests bacteria. This suggestion is
made on the supposition that the " filter-passers " have
not yet been named in biology. The word is made from the
Greek ei/as, a unit.
It is not needful to give here the already long and growing
list of organisms that have been found to have a microhenad
phase or phases ; the details of the technique of filtration as
used for molluscum virus is given below, p. 117.
The Kinds of Filter used for Virus-filtration. Besson lays
down that too fine a filter must not be used ; a Berkefeld ' V,'
or a Chamberland ' F.' The former is made from infusorial
soil and hence is composed largely of silicious skeletons of
PLASSOMYXINEAE 109
diatoms, the Chamberland is of porcelain, and the ' F ' is its
ordinary form. The filter must be new and be sterilised
before use. Filtration must be done soon after the liquid
to be filtered is prepared: Dr. Perkins tells me that with
time typhoid bacilli will grow through any filter. As a
control the water used for dilution may contain motile
bacteria.
Historical Notes of Virus Filtration. The virus of foot
and mouth disease was the first to be filtered by Loeffler
and Frosch. Borrel found no cell-inclusions in this disease,
but areas of leucocytic invasion between the layers of
epidermal cells.
Pleuropneumonia of cattle was filtered by Nocard and
Roux in 1898. This virus in rabbit's serum requires to be
diluted with 20 to 30 vols. of water before it can pass into a
collodion sac.
Saponin does not affect bacteria, but it has been found
to kill microhenads except those of trachoma and cyano-
lophia gallinarum. Saponin is a nitrogen-free gluco-
side obtained from the horse-chestnut and many other
plants.
Remlinger, who first showed that rabies virus can be
filtered, began his account : " It is classic to say that the
virus of rabies is stopped by filters." In the same way we
can say that it is " classic " to say that the virus of syphilis
is not filtrable. Now, from the presence of large plasson
bodies in this disease, I am sure that, if taken at the right
110 PROTISTS AND DISEASE
stage, this virus also will be filtered, indeed one positive
result has already been recorded by Jahnke.
Remlinger used immediate rapid filtration through a
Berkefeld 'V.' In prolonged filtration this filter becomes
imperfect. Fixed virus obtained from the brains of rabbits
the spinal cords of which had been used in antirabic treat-
ment was the material he employed. We may best appreciate
the facts connected with filtration of living organisms by
studying some of the records. A method used for molluscum
is given below in this Chapter.
Sheep-pox virus Borrel got by scraping the under surface
of skin removed from a large pustule 5 to 6 cm. across.
This mixed with 100 c.c. of tap- water proved to be virulent
after filtration through a Berkefeld filter, the filtrate giving
no growth on the usual media. Rous found a transplantable
spindle-celled sarcoma in chickens ; it had a filtrable virus,
which reproduced similar tumours in fowls ; and when
injected into eggs, on the membranes, and sometimes on
the body of the chick.
The Size of Microhenads. Speculations on this subject
have been numerous ; K. T. Hewlett has given us data by
which we can form a mental picture on the supposition that
microhenads are rigid solid bodies : " Visually, when an
object comes into the region of a little under one fifth of a
micron you cannot see it, even though you use the very
best lenses. Although an object of such dimensions is very
small, compared with molecules it is of course very large ;
PLASSOMYXINEAE 1 1 1
you may have a very considerable number of ultimate
particles of matter in a body of such dimensions. So that
there is no inherent difficulty in conceiving that micro-
organisms may possess such small dimensions as those I
have just given. (A micron = 25 o o inch.) "
Anyone who has watched the streaming subdivisions of
Plassomyxa contagiosa is forced to conclude that such
plastic living matter may pass through a filter in masses
easily visible, equivalent to many microhenads joined
together.
The filtration of molluscum virus has as yet been effected
only after comminution, and thus another possibility arises,
namely, that the virus may be in fractions of units, which
recombine in the filtrate.
Notes on the Histology of the Molluscum Tumour. This
aspect of molluscum has been dealt with in Part IV, where
it is shown that the accepted notion that the molluscum
body is a degenerated cell is based on superficial and
misleading histology : only a few details need mention
here.
Part of a section of a lesion of pin's-head size is shown in
Fig. 30. Parasites at b and c have escaped from the host-
nucleus and expanded in stellate form, staining less deeply
than still younger forms. The larger parasite near the
middle of a shows chromatic points throughout, these
suggest that a readjustment of chromatin occurs at this
stage. The granular chromatic matter in the oldest bodies
112
PROTISTS AND DISEASE
FIG. 30. a, PART OF A SECTION OF A MOLLUSCUM TUMOUR. Various
stages of the molluscum bodies are shown in the epithelial cells, in
most of them chromatin in the form of chromidial granules is present ;
b, a very early stage, a non-nucleated stellate amoebula apparently
within the nucleus of the epithelial cell ; c, two amoebulae between
the nucleus and the cytoplasm of an epithelial cell ; d, the molluscum
body is larger and consists of a plasmodium of extremely small stellate
amoebulae ; e, a still larger parasite ; the individual amoebulae have
fused together and the body is finely granular, a, x 600 diams. r
the rest x 800 diams. Drawing eye-piece. From Part IV.
PLASSOMYXJNEAE 113
is, I think, extruded to construct the capsules, &c. that are
formed in water-cultures.
In a valuable piece of work noticed below on the method
of filtration of the virus of molluscum the authors begin
with the premise : "It has been conclusively demonstrated
that they (the molluscum corpuscles) represent peculiar
forms of epithelial degeneration ; " and as the basis of this
belief, they refer to " the excellent pathologic studies of "
here follow five names, none of which I have found in any
list of those who have added to our knowledge of Phyco-
mycetes and Mycetozoa. The authors who took great care
in making one set of experiments evidently omitted the
simple precaution of examining for themselves by the best
methods the minute structure of the molluscum tumour.
It is in this way that errors are perpetuated.
Further Cultural Results. For the material on which
some of my latest cultural observations were made, I have
the pleasure of thanking Dr. G. Fernet, physician in charge
of the department for diseases of the skin at the West
London Hospital, and the house-surgeon, Dr. Barker. I
have also to thank Dr. Beverland and Mr. H. K. Shaw,
resident medical officers at the Hampstead General Hospital,
for helping me with the preparations. The lesions were
placed in covered Petri dishes, one without any addition on
a cupped slide, the others on tea-leaves, as described in
Part IV, with the addition of a sterilised solution of
glucose and peptone, each 0*2 per cent., which had been
8
114 PROTISTS AND DISEASE
prepared beforehand. All the preparations gave positive
results.
I was able to demonstrate the movement on the third,
fourth, fourteenth, and fifteenth days to seven different
trained observers, four of whom are expert in pathology.
In these demonstrations the movement was shown under a
magnification of 500 diameters with a dry objective. The
oil-immersion lens when used for preparations simply
mounted in water has the drawback of dragging on the
cover-glass and causing movements in the objects beneath it.
This set of preparations I last examined on the thirty-
fifth day after making the cultures. On this occasion
commotion was present in a few only of the corpuscles, and
the rest were obviously degenerating and becoming stained
by the colouring matter of tea-leaves on which they were
placed. So long as they remain in full vitality they do not
absorb the colouring matter.
In addition to facts mentioned above, Fig. 31 shows
the appearance and distribution of contaminating bacteria
in molluscum cultures.
To anticipate what will become clear after smallpox,
syphilis and cancer have been considered in Chapter X, it
may be observed that Plassomyxa contagiosa passes through
certain phases in water outside the host-body, whereas the
parasites of smallpox &c. pass through the corresponding
phases inside the host-body.
The Incubation-Period of the Filtered Virus. One of the
PLASSOMYXINEAE
115
latest communications on Molluscum Contagiosum that
have come to my notice is a paper by Udo. J. Wile and
Lile B. Kingery. The authors' task was to test the question
of filtrability of the virus. They quote Marx and Sticker
on molluscum contagiosum of birds : " sterile " filtrate
7.
FIG. 31. VARIOUS CHANGES IN MOLLUSCUM BODIES AFTER BEING KEPT
IN WATER AT ROOM TEMPERATURE FROM Six TO FORTY-SIX DAYS.
1, Unchanged save cortical layer clearer ; 2. motion in clear central
part ; 3, two with motion throughout, except in some skeletal parts
and in the cortex, which shows an opening in both. The granule in
the upper body was of a deep crimson colour ; 4, motion throughout
except in the skeletal part the granule above x, Y, was first seen
at " x," it moved to " Y," and then to where shown ; 5, encapsuled
body, motion in middle part and in the part which bulges into the
intracystic space ; 6, body in which a trophonucleus had appeared
after slight motion in adjoining granules ; 7, body with trophonucleus
and several clear spaces but without motion. X 500 diams.
rubbed into scarified areas on the comb of fowls having
produced lesions in eight to ten days. Marx and Sticker
found that the virus was extremely resistant to heat, light,
and cold, and that its infectivity was maintained when the
material had been kept for a considerable time in glycerine.
FIG. 32. PLASSOMYXA CONTAGIOSA IN CULTURES. 1, Bodies seen in a
teasing of a bacteria-free culture on the fourth day ; a, a body with
framework developed and which showed protoplasmic movement
throughout ; b, a body similar to a ; c showed protoplasmic move-
ment in part only of its extent ; its framework is imperfectly formed ;
d, a body which showed a framework but no motion ; e, one of three
minute motile bodies ; /, highly refracting globules ; g, epithelial
cell ; 2, body with imperfectly formed framework which had all its
protoplasm in motion, and a minute body escaping at a gap in the
contour ; 3, molluscum body segmented, the protoplasm of one
segment only in motion ; smaller spherical bodies, two with vacuoles
and two with protoplasmic motion ; 4, two zoospores with oscillating
granules and molluscum body with similar moving granules ; 5, mol-
luscum body extruding globules similar to those in 1, f. All the fore-
going drawn by the aid of the drawing eye-piece ; X 800 diams.
PLASSOMYXINEAE
117
FIG. 32 continued.
6, four molluscum bodies and an epithelial cell as seen with a dry
lens ; one molluscum body showed protoplasmic motion ; 7, four
molluscum bodies, one encapsuled, another segmented ; 8, molluscum
body encapsuled within an epithelial cell ; 9, similar to 8, but showing
a globule being extruded ; 10, encapsuled molluscum body, bacteria
outside but not inside the capsule ; 11, unencapsuled molluscum body
segmented and invaded by bacteria : this is the end of a culture
that is contaminated. Figs. 6 to 11 X 400 diams. From Part IV.
Tumours were ground up with 1 to 2 c.c. of saline solution
by means of a pestle and mortar, and filtered through the
smallest available Berkefeld filter, the porous surface being
reduced by paraffin. The emulsion was filtered by suction
and divided into two portions, which were injected by a fine
needle intradermally into the backs of two volunteers, after
having been found to give no growth on agar jelly. In the
first case, typical lesions were obtained in fourteen days, in
the other case, faint erythematous patches were observed
after twenty-five days, and for three weeks these remained
stationary, and then became typical lesions. Histological
examination confirmed the clinical diagnosis. The article
118 PKOTISTS AND DISEASE
is fully illustrated, and shows, in the authors' opinion, that
the lesions obtained were developed in connection with
hair-follicles and sebaceous glands. The authors believe
that the lesions are recognisable clinically before the mol-
luscum bodies develop, and conclude therefrom that the
bodies are degeneration-products. Their results confirm
previous findings to the effect that the virus of Molluscum
Contagiosum is filtrable.
The Identity of Plassomyxa Contagiosa with the Filtered
Virus. When one examines in sections a fully-developed
tumour, e.g. Plate III, Part IV, it is seen that the proportion
of parasites to host-tissue is very considerable. Roughly,
one-third of the weight of the tumour must consist of the
parasites, and a casual relationship of the latter to the
disease is thus seen to be more than probable.
Again, it is certain that parasites which cause the disease
are contained in the filtrate of experiments, such as that of
Wile and Kingery.
There is no inconsistency in the two groups of facts.
After the use of the pestle and mortar biological units,
capable of being drawn by suction through the pores of the
filter, are free in the liquid medium. Such units, I do not
doubt, are a plasson phase of Plassomyxa contagiosa.
Synchytrium and Plassomyxa contagiosa compared.
Comparable features in synchytrians and the causal parasite
of molluscum are found in the nucleolus of the former and
the whole body of the latter. Invisible in its earliest stage
X
PLASSOMYXINEAE 119
the synchytrian nucleolus appears and grows rapidly by
general increase : Plassomyxa appears first in the host-
nucleus, is next seen in the cytoplasm where it grows rapidly
in the nucleolar state until it is full-grown ; reproductive
action by the zygotic nucleolus of Synchytrium produces
the generative chromidium. The later changes in Synchy-
trium end in the production of zoospores when the ripe
resting-cell has been in water some days : the formation of
flagellate zoospores occurs also in water-culture of Plas-
somyxa, but the latter has alternative phases, e.g. gemmation
of the parasite with streaming protoplasm. The formation
of the capsule of the synchytrian zoosporangium is repeated
in Plassomyxa, definite doubly-contoured capsules being
frequently formed ; the formation of a supporting frame-
work is an alternative to this.
The Geographical Distribution of Molluscum. The late
S. von Prowazek * found that the occurrence of this disease
was variable in the tropics. It had been met with in Samoa,
Brazil, Java, Sumatra, New Guinea, China, and abundantly
in East Africa.
Avian Molluscum or Bird-pox
This disease affects domestic poultry of all kinds, cage-
birds, and wild wood-pigeons. It so closely resembles
human molluscum that the question of identity arises.
1 S. von Prowazek, one of the editors of the " Archiv fur Protistenkunde," died of
typhus whilst investigating that disease in 1915.
120 PROTESTS AND DISEASE
A case in which a lady appears to have caught the
disease from a canary has been recorded, so Dr. Fernet
informs me.
Marx and Sticker found the virus to be filtrable by a
Berkefeld filter. They found it more resistent to cold, sun-
light, drying, and heat than any other filtrable virus. The
filtrate dried in vacuo resisted heating to 100 C. Passage
of the virus from pigeons through hens diminished virulence
for pigeons. An extensive attack conferred immunity.
Burnet found that inoculation of the cornea produced
bodies like the Guarnieri bodies in the vaccinated cornea.
L. Pfeiffer found that in hens and turkeys the disease
ran a chronic course and the lesions were confined to the
comb, wattles, &c., not invading the mouth. Young pigeons
are especially disposed : tumours as large as hazel-nuts
forming about the head and anus. Lesions form at the
angles of and inside the mouth, sometimes extending along
the trachea and intestine and causing rapid death. Pfeiffer
found a close relationship between molluscum and what
he named flagellate- diphtheria in pigeons, an affection in
which diphtheria-like membranes cover the mucosa of the
mouth, trachea, and intestines. Millions of flagellates crowd
the membranes. He identified them with Trichomonas.
His drawings show large multinucleate bodies with one or
two flagella, some appear to have been attached by a
pedicle. In view of the flagellate bodies which I saw
develope in water-cultures of human molluscum Pfeiffer' s
PLASSOMYXINEAE 121
disease of pigeons calls for re-investigation. Burnet quotes
Carnwath as having found the virus of bird-pox to be the
same as that of flagellate-diphtheria.
Pfeiffer described the healing of lesions in pigeons to
be like that of human vaccine vesicles.
The molluscum body in birds has been described as
" melting away " when placed in water. I have seen nothing
like that in human molluscum ; but it is quite possible that
in birds the bodies grow more rapidly, are softer, more
labile, and in water break up quickly into microhenads.
Inoculation of a bird, M. Borrel observes, is easy : all
that is required is to rub a little virus on a feathered part
and multiple tumours follow just as vaccine is followed by
vesicles if rubbed on the shaven skin.
Bird-molluscum must be one of the easiest of all diseases
to investigate. All the necessary material can be obtained
in the course of treating an ailing pigeon medically, with as
much consideration as though it were a human being. No
pain need be caused. No license to experiment on living
animals is required for most of the work.
Further Details of Culture-Method. In giving these
simple instructions I have a hope that others who have
access to material may be led to repeat and extend, or to
correct my observations, which have been too often inter-
rupted by other affairs.
The necessary apparatus need not occupy more than a
square foot of space in a consulting-room and cannot but
122 PROTISTS AND DISEASE
be pleasing to the eye : two pairs of Petri dishes and two
watch-glasses being all that is required besides the micro-
scope, slides and covers, mounted needles, wire loop, &c.
which already find their places.
The patient's skin should be cleansed with ether and
absolute alcohol, no strong antiseptic being used. Water
should be taken after the tap has been allowed to run a few
seconds, in order to remove traces of copper, and boiled, as
also should all watch-glasses, Petri dishes, slides, &c.
A watch-glass is placed in the lower of each pair of dishes
and some water (not enough to float or cover the watch-
glass) is poured into the lower dish, Fig. 28. One dish is left
covered by its upper half ; into the watch-glass of the other
is placed a little heap of excised lesions cut open from the
surface downwards ; or of the white wax-like material
squeezed out of ripe lesions. For small portions a cupped
slide may replace the watch-glass. A few drops of water,
but not enough to cover the heap, are now added and the
upper half of the dish is placed over the lower. Rain-
water might suit better than tap-water. Streaming occurs
with normal saline, and the addition of a trace of bicarbonate
of soda to the latter favours subdivision of the bodies into
segments.
The cultures must be kept at room-temperature.
CHAPTER VII
PLASMODIOPHORACEAE
THIS name was given by Zopf in 1885 to a group of organisms
related to Mycetozoa. The prototype genus of the group is
Plasmodiophora. At a later date the same group was called
Phytomyxineae, a supposed genus " Phytomyxa " being
based upon a misinterpretation of objects seen in sections
of root-tubercles of leguminous and other plants : " plasmic
masses " and rod-shaped and angular " spores " being
described. These were the bacteria that cause the tubercles,
the plasmic masses being their mucous secretion.
The bacteria of root-tubercles benefit their hosts and
the land on which these grow. The Plasmodiophoraceae,
on the contrary, are destructive parasites. The group is
divided into genera according to the form and arrangement
of the spores, thus : -1, Plasmodiophora, with free regularly
shaped spores ; 2, Tetramyxa, spores in groups of four
enclosed in a membrane ; 3, Ligneria, variously shaped
spore-groups ; 4, Sorosphaera, spores grouped in a hollow
sphere ; and 5, Spongospora, spores forming a sponge-like
ball.
123
124 PROTISTS AND DISEASE
Its relationship to the Mycetozoa proper gives this group
a theoretical interest ; its power to cause disease in food-
plants a practical economic interest ; and in addition, the
likeness the trophic nuclei have to the " endogenous cells "
of cancer &c. gives these parasites a definite interest for
students of human pathology.
As examples a member of genera 1, 4, and 5, will be
briefly described here.
Plasmodiophora Brassicae (Woronin, 1877). This parasite
causes irregular lumpy growths, known as " finger and toe,"
or " anbury," on the roots of several cruciferous plants ;
cabbage, turnip, etc. In certain localities it has done serious
damage, numbers of the infected plants being killed, and
others rendered useless for the table. The appearance of
the rootlets of a diseased cabbage is shown in Fig. 33 : 1,
a and b. The spores are said to remain dormant in the earth
during winter, and infect the next spring crop. The cortical
layers of the root are irregularly thickened and of an opaque
grey colour. The spore hatches out a zoospore, 3, which
penetrates a cell near the growing point of a rootlet. The
host-cell has a nucleus surrounded by a sheath of cytoplasm,
strands of which join that lining the cell- wall ; sap-vacuoles
occupy the intervening spaces. In this environment the
parasite becomes amoeboid, and in the earliest stage recog-
nisable by the microscope, it possesses two or more nuclei,
each with a nucleolus, round which is a clear space separated
by a sharp boundary from the cytoplasm, 1. These nuclei are
PLASMODIOPHORACEAE
125
trophic, and have been compared to the " bird's-eye "
bodies of cancer, and with which, I believe, they may be
homologous. In this intracellular stage the parasites appear
to subdivide without any nuclear division. They occupy
FIG. 33. PLASMODIOPHORA BRASSICAE. 1, Rootlets of infected cabbage ;
a, surface view, after Woronin ; b, section, after L. Pfeiffer ; 2, section ;
a, 4 multi-nucleate parasites in a cell ; 6, plasmodium, the nuclei
subdividing ; c, and d, spore-formation ; 3, stages in the hatching of
a zoospore. x 250 diams. From Part I., modified from Doflein
after Woronin.
an increasing amount of the space in the cell, and are said
to fuse together into a plasmodium, 2, a and b.
The nuclear processes in Plasmodiophora are shown in
Fig. 34.
The trophonuclei lose their chromatin, which passes
into the cytoplasm, 1 and 2. The reproductive nuclei are
126 PROTISTS AND DISEASE
then formed. They differ from the trophonuclei by having
no nucleoli. Two successive karyokineses then take place,
and the plasmodium subdivides into spores, 4.
The absence of a Capillitium from the life of Plasmo-
diophora distinguishes it from the Mycetozoa, but such
distinctions are not radical : such features might be
suppressed in parasitic adaptation.
The absence of a sporangium allows the spores, which
WjF^
vk :?: /M
ff
FIG. 34. PLASMODIOPHORA, NUCLEAR PROCESSES. 1, Amoeboid stage
with trophonuclei ; 2, chromidial or akaryote stage ; 3, karyokinesis
in new nuclei ; 4 and 5, spore-formation. From Part III. After
v. Prowazek.
are in great numbers, distending the otherwise empty cell-
walls of the host, to collect into roundish masses moulded
to the space in which they are contained.
The individual spores have a thin doubly- contoured
capsule. In August, 1918, a friend gave me some badly
diseased cabbage-roots from his garden at Chesham Bois,
Bucks. a rather heavy, chalky, and flinty soil. I made
many observations on scrapings from a slice of root kept
partly in and partly out of water, but I did not succeed in
PLASMODIOPHORACEAE
127
seeing the hatching of a zoospore, though many small
monads were present.
Sorosphaera Veronicae. This parasite has been de-
11
FIG. 35. SOROSPHAERA VERONICAE. 1, A tumour on a Veronica plant ;
2, plant-cell with nucleus and starch grains in protoplasm ; 3, multi-
nucleate parasite in host-cell, in which are no starch grains ; 4, two
trophonuclei with surrounding plasmodioplasm ; 5, prophase of
trophonuclei ; 6, akaryote stage ; 7, new nuclei forming from akaryote
state ; 8, metaphase of reproductive nuclei ; 9, plasmodium separating
into nucleated subdivisions, one nucleus at metaphase ; 10, the
second simultaneous division of reproductive nuclei ; 11, spores formed ;
12, spores arranged in spherical sorus. 1, nat. size, after Blomfield
and Schwartz ; the rest X 1000 and drawn from a preparation by
Blomfield and Schwartz.
scribed by Blomfield and Schwartz. The host-plant shows
tumours in various parts, Fig. 35, 7, on stems, petioles, and
128 PROTISTS AND DISEASE
leaves. Seedlings were infected by sprinkling them with
water in which tumours which had been dried and pounded
in a mortar were suspended. The vegetative period begins
as an amoeba having one or two nuclei lodged in the cyto-
plasm of a procambial cell of the host-plant. The amoebi-
form parasite grows, its nuclei increasing in number, and
it is termed a plasmodium. Several such may be
contained in the same host-cell which is then greatly hyper-
trophied. Mitoses are frequent in the nuclei of the host-
cells.
The authors kindly gave me a section of one of the
Veronica tumours. Fixed in Bouin's solution (formol 10 c.c.,
saturated aqueous picric acid 30 c.c., and crystallisable
acetic acid 2 c.c.), and stained in Benda's iron haematoxylin,
it shows the features described by the authors very clearly.
The dividing trophonuclei at metaphase are cruciform,
the elongated nucleolus having a ring of chromatin around
it. The nuclei shown in Fig. 35, 5, are in a prophase :
Maire and Tison give a similar drawing and state that it
shows " separation of idiochromatin from trophochromatin
in prophase of nuclear division."
The spherical sori with spores arranged peripherally
round a central space are a striking feature in the sections.
A chromidial stage followed by two ordinary reproduction-
mitoses ends in spore-formation, which differs from that of
Plasmodiophora only in the formation of a sorus.
Spongospora scabies is the cause of corky scab of the
PLASMODIOPHORACEAE 129
potato. Massee informs us that Berkeley, who first described
this parasite, and others classed it with the smuts because
the spores are formed in groups.
The lesions on the potato vary from small scabs to
cavities lined with a dense layer of snuff-coloured spores.
Massee states : " The plasmodium appears to be active
only during the period when the tuber is growing, and
passes into a resting condition when the tuber is dormant
during the winter. In the spring, when the potato com-
mences to sprout, the plasmodium again becomes active
and migrates from the old tuber or set into the new tubers
formed during the process of growth."
The foregoing calls for re-examination : it is probable
that infection of the young tubers is produced by hatching
of zoospores from the infected " set."
Whether some species of this order attack animals is a
question worth considering. Leger and Hesse described
" A New Protist Parasitic in Otiorhyncws" The parasite,
Mycctosporidium talpa, infests the epithelium of the whole
of the intestine of the beetle, and the authors leave it doubtful
whether it is a Haplosporidian or a " Mycetozoon."
Several points connected with this group still require
to be made clear. Do the zoospores multiply by fusion
and conjugate ? What are the earliest intracellular states
of the parasite ?
Schwartz doubts the conjugation that v. Prowazek
described in the course of formation of spores.
9
130 PROTISTS AND DISEASE
At the close of the chromidial stage Prowazek and
subsequent writers found that the new nuclei appeared in
the old nuclear cavities. In this section all the chromidial
parasites are finely granular throughout, Fig. 35, 6, and no
remains of nuclear cavities can be traced ; also the nucleated
state is reconstituted by the fusion of granules at equi-
distant foci, Fig. 35, 7 : a good example of free nucleus-
formation.
Opinion as to the relative position of this group is in
favour of its being placed between the Chytridians and the
Mycetozoa proper.
CHAPTER VIII
THE MYCETOZOA
THE group of organisms which de Bary named Mycetozoa
(fungus-animals) in 1859 are also known as Myxomycetes
(slime-fungi). Without practical knowledge of this group
no one can command a right perspective of the Protista.
The commoner kinds are to be found without much
trouble in pleasant places. A. Lister told us that Lampro-
derma scintillans is a most abundant species in England,
and how it appears in countless numbers in heaps of dead
leaves : in a dark fir plantation the stones and herbage by
the side of a rivulet appeared hoary over an area of many
square yards with the young rising sporangia, and a little
search showed the mature forms in equal abundance.
Mucilago spongiosa may be unpleasantly abundant : G.
Massee wrote : " Its plasmodium often creeps up the
stems of living grasses, and forms spore-masses up to 2-3
inches in length and an inch in diameter. . . . The dense
masses of spores are said to injure vegetation by a process
of suffocation. . . . Horses and other animals, have suffered,
131
J32 PROTISTS AND DISEASE
even died, from the effects of having eaten the masses of
spores adhering to grass &c."
Mycetozoa are counted among the lowest forms of life
and yet they exhibit a wonderful range of form, and a
series of physiological processes of the highest interest.
They make a small group, about 180 British species
being known, hence they offer a compact example for
classification.
To have written a fitting account of them would have
made this the longest chapter of the book. But, seeing
that the " British Museum Guide to the Mycetozoa " can be
bought for one shilling, and that it is a giiide to both the
biology and the systematic arrangement, great pruning is
possible. No guide, however, can take the place of practical
personal study.
In their active states mycetozoa are aquatic and semi-
aquatic in habit. A long spell of wet weather favours
them.
Stages in the life-cycle. To-day a mycetozoon may be
a plasmodium varying in size from a mere speck of soft
protoplasm in some cases to an area of a square foot or
more in Fuligo septica, the ' flowers of tan ' ; to-morrow,
perhaps, it is one or many brittle sporanges full of spores ;
and, a day or two later, with rain, the spores become shoals
of flagellate zoospores ready to recommence the cycle.
In size and colouring, and in the sculpturing of their
outer coat the spores resemble those of many fungi. If kept
THE MYCETOZOA 133
dry they remain alive for over three years. Many species
pass their period of growth, i.e. their plasmodial stage,
among decaying leaves, others grow hidden within rotten
wood, emerging only to form sporangia. Shady spots where
leaves are left in heaps suit such species as live among dead
leaves : the stages of one of these are shown in Fig. 36, and
in the Frontispiece a place in which it throve. The zoospores
swim and creep alternately ; owing to frequent binary
division they are often seen in pairs joined base to base,
struggling to be free from each other. With patience even
in simple slide-and-cover cultures the fusion of two zoospores
that have withdrawn their flagella may be seen ; thus is
formed the zygote or plasmodium at its inception.
On cultivating spores in water we notice how variable
is the hatching process both in the same and in diiferent
species ; the spores of Reticularia Lycoperdon usually have
the spore-capsule thinned at one side, and they often hatch
in an hour.
Most species require 12 hours, some much longer. When
hatching has occurred we note that the characters of zoo-
spores of different species vary : in the winter species,
Trichia varia, for example, the zoospores move in a leisured
way, and the nucleus is hard to detect ; those of Didymium
and other genera move briskty and their nucleus and
nucleolus are plain to see.
Stages of sporange-formation. As seen in a species of
Stemonitis stages of sporange-formation are shown in
FIG. 36. Description on opposite page.
THE MYCETOZOA 135
FIG. 36. STAGES IN THE LIFE OF DIDYMIUM DIFFORME,
DUBY.
1, PLASMODIUM OR CREEPING FILM ON A DEAD LEAF ;
2, DIFFERENT VARIATIONS AND STAGES SHOWN AS IF ON THE SAME LEAF :
1, the smallest discrete elements ; 2, larger discrete elements separated
from a continuous patch, which at one point 3, is heaped up in a
rounded nodule with small secondary projections ; 4, sporangia,
dark from the purple spores ;
3, SPORES, CAPILLITIUM FILAMENTS, AND CRYSTALS : one of the spores
has not yet formed its capsule, the beginning of which process I
watched under the microscope. In its early stage the capsule is of
a rose-colour, later the pigment is purple-brown and is condensed in
the points which project from the surface of the capsule. Drawing
eyepiece. X 800 diams. ;
4, THE HATCHING PROCESS : a, spore , b. swarm-cell escaping from spore-
case ; c, newly hatched swarm-cell containing a nucleus and three
vacuoles ; d, flagellated swarm-cell ; e, swarm-cell with two vacuoles
containing bacteria, and produced at the posterior end into pseudo-
podia, to one of which a bacterium is attached : /, amoeboid swarm -
cell. X 720. After A. Lister ;
5, STAGES IN THE INCEPTION OF A BACILLUS BY A ZOOSPORE. After A.
Lister ;
6, YOUNG PLASMODIUM WITH ATTENDANT AMOEBOID SWARM-CELLS, SOME
OF WHICH HAVE TURNED INTO MiCROCYSTS : v, vacuole containing a
microcyst ; ,<?, empty spore-cell, x 450 diarns. After A. lister.
136
PROTESTS AND DISEASE
Fig. 37, based on the drawings and description of Mr. A. E.
Hilton, who kindly gave consent. The specimen was
found in the Highgate woods ; six weeks of wet weather
had preceded its appearance. The plasmodium had grown
in a tree-stump and on emerging it had crept upon the
surface of a flat fungus and had assumed the cushion-shape
FIG. 37. STAGES IN SPORANGE-FORMATION IN A SPECIES OF STEMONITIS.
The time between a and d was 20 hours, a to d. after A. E. Hilton ;
e and/, from the same author's description.
shown at a. Smooth at first, its surface soon became sub-
divided into dome-shaped segments ; the mass then in-
creased in height and shrinking at its base, leaving traces,
called the hypothallus, on the substratum. As the changes
in form proceeded the colour changed from white through
deepening shades of brown to black, then to brown again
THE MYCETOZOA 137
as the sporanges dried, becoming separable, brittle, and easy
to detach from their stalks.
The manner in which the stalks are formed and prolonged
into the columella as seen under low magnification is shown
in Fig. 38, 7 to 10.
A small plasmodium may become a single sporange.
Sporange-formation as seen in Trichia, Arcyria, and other
genera with clustered fruits begins in the same way as in
Stemonitis. In some genera such as Eeticularia, and Fuligo
the sporangia fuse into a mass called an aethalium.
The most familiar example of an aethalium is perhaps
that of Lycogala epidendrum, whose plasmodium emerges
from rotten wood as coral beads and whose fused sporanges
make rounded bodies like small puff-balls, Fig. 43, 15, and
change from rose-colour, through grey to brownish. The
collection of grey-pink spores within the tough membrane
of the ripe aethalia farther reminds one of puff-balls and
explains how the whole class of Mycetozoa were at one time
called Myxogastres, and were thought to belong to the
same group of fungi as the Gasteromycetes.
In Ceratiomyxa fruticulosa, Fig. 45, the single species
which constitutes the exosporous subdivision of the Myce-
tozoa, the sporangia are not closed ; the spores being
formed at the end of short stalks on finger-like sporo-
phores.
The life-history of Mycetozoa is still imperfectly known :
I have found spores unchanged in the gut of earthworms ;
L 38. SOME DETAILS OF MYCETOZOA. 1, Branched end of a plasmodium growing c
a microscope slide ; la, two amoebulae, which united to form the plasmodium (below
2, encysted plasmodium which has incepted seven spores (these were carried round
continuous rotation) ; 3, a young plasmodium in a resting state ; 4, the same plasmodiu
active, its hinder (upper in this Fig.) end is studded with hair-like processes ; 5, the ei
of a receding strand with similar processes ; 6, element from a sclerotium ; 7, cluster
young sporangia of Stemonitis ferruginea ; 8, optical section of one element of the sam
showing a central axis separated to form the beginning of the columella ; 9, sporangiu
of the same species further advanced, shows the continuity of the columella with t]
general framework below ; 10, the same still older, showing the protoplasmic body h
drawn upwards leaving the lower part of the central support free as the stalk ; 11, stal
columella. and capillitium of a fully developed sporangium of Comatricha nigra : no
absence of the sporangium wall and of spores ; 12, two of the tubercles, by which o;
Stemonitis sporangium abuts on another ; 13, first stage of the middle of an elater
Trichia varia ; 14, half a fully developed elater ; 15, part of the same after treatme
by potash solution. After de Bary ; la, After Cienkowski, from de Bary.
THE MYCETOZOA 139
these animals may play a part in the conservation of some
species.
The plasmodium. The first picture of the beginning of
a plasmodium was that of Cienkowsky reproduced in
Fig. 38, la ; the latest is that of Jahn, Fig. 40, E. Jahn's
picture shows that the spores of Mycetozoa are encapsuled
gametes, and that the plasmodium is at first a single zygote.
De Bary describes the grown plasmodium as consisting
of a ground-substance with granules scattered through it
in greater or less proportion, according to the species. At
the surface the ground-substance may be quite clear, forming,
except over the young pseudopodia, a doubly-contoured
line of ectoplasm.
Alcohol, glycerine, and zinc chloride solution cause the
inner protoplasm to shrink and remain attached at a few
points only to the cortical layer or hyaloplasm.
The Granules. The larger of these consist of carbonate
of lime in the Calcarineae, the other granules being very
small. Where pigment is present it is in fluid form, and it
invests the lime granules.
Colours. The plasmodia in many species are white,
but others are yellow, pink, purple, or green, and owe their
colour to a fluid pigment scattered in small drops through
the protoplasm. The whole plasmodium of Lycogala epiden-
drum is rose-red. The spore-capsules are coloured in most
species, and in Didymium difforme colour is recognisable in
the hyaloplasm, out of which the spore-capsule is secreted.
140 PROTESTS AND DISEASE
De Bary mentions that some of the colouring matter is
soluble in alcohol.
Protoplasmic motion or Streaming. This is seen in
most plasmodia. The stream is in the course of the strands
of the network, and it follows their subdivisions, but it may
be arrested in a main strand and continue in side branches.
At the edge of a plasmodium streams may run in opposite
directions in neighbouring pseudopodia.
Streaming may be modified into rotatory motion. In
Fig. 38, 2, is an instance. In an encysted plasmodium the
endoplasm and incepted bodies were in " perpetual rotation."
Another resting plasmodium is shown in 3 ; 4 is the same
plasmodium become active, and it has fine processes resem-
bling cilia covering its hinder third. A similar condition is
seen in 5, which represents the end of a receding strand.
A. Lister filtered through wet cotton-wool a plasmodium
of Badhamia utric. containing spores of Slereum. The spores
were left behind, the plasmodium passed through emerging
in separate parts which fused together again.
Plasmodia of different species vary greatly in consistence.
From those of Badhamia utricularis and Didymium difforme
I have been able under water to detach portions by a needle,
float them on to a slide ; and, when covered, they have resumed
all their activities. In another species I found abundant
on straws of a recent part of a heap of horse-stable manure
the plasmodium crept actively from the straws over the
wet surface of a Petri dish and examined there under a
THE MYCETOZOA 141
magnification of 60 diams. showed typical streaming, but so
fragile was the plasmodium that on covering with a thin
cover-glass after adding a drop of water it broke up into
chalky subdivisions.
The sclerotium. This resting state is one of the most
important phases of Mycetozoa. It develops only from
mature plasmodia, and
was discovered and
named by de Bary. The
beginning resembles the
first step towards spore-
formation : the plas-
modium concentrates at
points and breaks up
FIG. 39. SCLEROTIUM OF DIDYMIUM COM-
into segments, Fig. 39, a ; PLANATUM. a, The whole sclerotium
all food remains are re- about natural size ( {i had f rmed on a
moss-stalk) ; 6, part of a section, from
jected. Most, but not which the contents of two cysts have
,, . fallen out ( x 250 diams.) ; c, return
all, mycetozoan sclerotia of two elements to the amoeboid state.
may be regarded as a x 25 diams - From Doflein > af ter de
protective encystment,
and compared to the formation of microcysts or to hypno-
cysts in protozoa.
On being completely dried the sclerotium assumes a
horny brittle consistence. The minute subdivisions are
either round or oval, or, from mutual pressure, polyhedral
in form. In the latter case a section may have a curious
resemblance to the parenchyma of a plant, but on being
142 PROTESTS AND DISEASE
soaked in water the cysts separate, 6, c. I have examined
many sclerotia of Didymium difforme but in none have I
found this regular segmentation. In Badhamia the segments
recall the multinucleate conidia of Mucor. Reviving
sclerotia should be watched in slide-and-cover prepara-
tions mounted in water. The protoplasm absorbs water to
form vacuoles, round which groups of oscillating granules
are seen; after this the segments coalesce and streaming
begins.
Nuclear processes in Mycetozoa. The zoospores have a
contractile vacuole and a nucleus, which is placed close to
the insertion of the flagellum at the narrow anterior end of
the organism. A. Lister described the nucleus of the zoo-
spores of Eeticularia Lycoperdon (Journal of the Linnaean
Society, 1893) at rest and in division and Jahn's description
and illustrations, Fig. 40, a to d, confirm Lister's, and his
account of conjugation of swarm-cells with karyogamy at
the beginning of plasmodium formation has been accepted
in biology.
Both de Bary and Cienkowski believed that the nuclei
of the swarm-cells disappeared when they coalesced to form
the plasmodium, Fig. 38 : la. In 1893 the fact that
some plasmodia have nuclei had been established by Schmitz
and Strasburger, as quoted by A. Lister, who wrote : "It
may be presumed that they are the persistent nuclei of the
swarm-cells and the results of their divisions."
There is a simultaneous karyokinesis of nuclei in the
THE MYCETOZOA
143
FIG. 40. THE ZOOSPORES OF STEMONITIS FLACCIDA (LISTER) AND PLAS-
MODIA OF PHYSARUM DIDERMOIDES (Rosx.) FIXED AND STAINED.
A, The fully developed myxoflagellate showing the relation of the
flagellum to the nucleus ; a contractile and a food vacuole are present ;
B-D, stages in mitotic division ; D, shows the formation of the
flagellum from the centrosome. From Doflein after Jahn. E, Plas-
modium-formation with fusion of nuclei ; F, Plasmodium with six
nuclei and incepted amoebulae. After Jahn. Compare Fig. 38 :
la and 2.
sporangium about an hour before spores are formed, see
Fig. 41.
144
PROTISTS AND DISEASE
In a section of a sporangium of Lycogala Vonwiller found
that the nucleus of every spore had beside it a small darkly
staining body which he terms a sphaeroplast ; A. Lister
described the same body in 1893.
The nucleated substance left in the stalk and to some
mm
*>^A
M
FIG. 41. NUCLEI IN SPORANGIA OF ARCYRIA INCARNATA. 1, Stage with
many small nuclei and finely granular plasm ; 2, a nucleus from 1 ;
3, stage with fissured plasm and larger crescentic nuclei, an early
stage of capillitium-tube present : 4, the first mitosis, blunt-ended
spindles, capillitium-tubes formed ; <5, the second mitosis, sharp-
ended spindles, a capillitium fibre apparently being formed by con-
fluence of granules ; 6, two nuclei more magnified ; 7, nuclei of
individual spores formed, spores not yet separated, a fully-formed
capillitium-tube ; 8, individual spores separated. 2 and 6, X 1000 ;
the rest, X 500.
extent in the hypothallus of Arcyria appears to be a simple
residue, the nuclei having the characters of resting nuclei.
They may perhaps be compared to the nuclei of Mucor that
remain in the conidiophore.
Jahn has found many small degenerating nuclei in
THE MYCETOZOA 145
sporangia, the element shown in Fig. 41, 2, may be the
converse of this : the formation of a nucleus by the confluence
of chromidial granules.
In Fig. 41, 5, the formation of a capillitium tube by the
confluence of chromatic granules is evident.
The details in Fig. 41 were drawn from one section
of a group of sporangia of Arcyria incarnata, the different
sporangia present being at different stages of evolution :
they are numbered as I think they come in order of age
beginning with the youngest.
Fertilisation. In Fig. 40, E, is shown the union of two
amoebulae with fusion of the nuclei ; the converse of cell-
division. The amoebulae are gametes and the fusion of
the two nuclei marks the completion of fertilisation in the
zygote. The chromosomes in the nuclei before conjugation
Jahn found to number 8, and after conjugation, 16 ; the
number lost in the reducing divisions being restored on
conjugation. Nuclei with the reduced number are termed
haploid, in distinction from the diploid or unreduced nuclei.
In many algae and fungi reduction takes place after
fertilisation.
Chromidial elements. Anyone who may have the good
fortune to find Didymium difforme growing profusely from
year to year a few yards from his study door, and will
examine every phase in the living state and in sections,
will, I do not doubt, find the chromidial stages described in
Part IV. Nodules such as that shown in Fig. 36, 2, 3,
10
146 PROTESTS AND DISEASE
appear to become a kind of sclerotium ; it was from one
such that the large double cells Fig. 18, Part IV,
developed.
In Fig. 26, Part IV, is shown a section of an early
sporangium ; in a plasmodial lobe are two large chromidial
bodies, and in a space between the lobes is what I called a
spore, but the different nature of which has been explained
by a later experience. In 1920 on teasing in water one of a
group of ordinary-looking sporangia of Didymium difforme
I found instead of the usual mass of dark brown spores
there were only one or two such in the field and no capil-
litium fibres ; but many concentrically striated bodies.
The latter in a slide-and-cover preparation first swelled,
and on the 4th day, expanded into streaks with a red core ;
the streaks changed into ordinary capillitium fibres. The
red colour was no doubt a prismatic effect ; the coloured
parts looked black when out of focus.
The chromidial processes appear to be used largely for
the production of capillitium elements ; I would designate
such chromidial matter skeletoplasm. I was unable to
find another sporange in which the concentric bodies were
present, but I found later that, if slides washed in water
and then wiped dry after they have been in 5 % solution
of lysol are used, sporangia of various Mycetozoa give when
teased in water a simulation of the red streaks with some
imitation of capillitium-formation. Lysol is made by boiling
either linseed oil or resin with tar oil, alcohol, and potash.
THE MYCETOZOA 147
Mitochondria were found to be abundant in Mycetozoa
by Cowdry (quoted by Sharp).
Conditions of life or bionomics, &c. From what has been
given above many of the habits and life-relationships of
Mycetozoa will have been inferred. In the growth-period
those that can be watched from their developing among
decaying leaves or on the surface of rotting wood, etc., are
attracted by moderate degrees of light and heat, and repelled
by extremes. Grown on glass with a minimum of food a
plasmodium of Fuligo sent out pseudopodia vigorously into
a solution of glucose or an infusion of tan brought into
contact with a part of it.
The plasmodium is rheotropic : when a gentle stream of
water is directed over a slide or through a strip of linen or
filter-paper and this is brought into contact with a plasmo-
dium, the latter moves against the stream on to and over the
substratum.
As to nutrition, the zoospores and plasmodium are
holozoic in many species, solid ingesta being digested in
food-vacuoles, the contents of which are acid, though the
reaction of the plasmodium itself is alkaline. Mycetozoa
have a facility for digesting cellulose, whether extraneous
or of their own making. The hyphae of Stereum hirsutum
can be seen to dissolve as the hyaline border of a wave of
plasmodium of Badhamia utricularis advances over them
(A. Lister).
W. T. Elliott found that the plasmodium of B. utricularis
148 PROTISTS AND DISEASE
placed on fungi other than Stereum varies considerably in its
relation : it crept all over a Coprinus, but was destroyed,
if it had not crept off when the fungus decayed ; it con-
sumed every part of Boletus flavus ; but did not consume
any part of Lycoperdon gemmatum.
The nutrition of species that grow in woody tissue has
been inferred to be derived from solutions. De Bary gives
the appearance of plasmodia of Lycogala in a section of fir-
wood lobulated protoplasmic masses, with no definite
relation to the cell- walls of the wood.
The chemical composition of the plasmodium of Fuligo
as described in 1881 is still quoted as being characteristic of
protoplasm in general.
A parasitic mycetozoon. Hymenobolus parasiticus was
found in Austria by Zukal in 1893 ; the species has been
found also in Scotland. The plasmodium of Hymenobolus
has no rhythmic circulation, and instead of spreading in a
network it forms a compact mass which eats its way into
the lichen or alga on which it feeds. In drought it contracts
to form a rose-coloured macrocyst. Its sporangia, which
usually have a lid, are drab or, from refuse matter, black.
Hymenobolus has no capillitium.
Culture of a Mycetozoon. Some Mycetozoa in cultures
pass rapidly into the sporangial state, but B. utricularis
can be kept in the plasmodial state almost indefinitely by
supplying it regularly with fresh Stereum.
Fragments of this fungus placed with water in a vessel
THE MYCETOZOA 149
such as a Petri dish and a small flake of sclerotium placed
on the fungus will in a day or two produce a plasmodium,
which in the course of a week in warm weather will cover
the greater part of the Stereum.
A square of glass should be placed over the culture in
such a way that a very small air- way is left at each side.
At a point near the middle of the glass the Stereum may
be brought into contact with it ; when hungry the mycelium
will spread widely over the glass. Now, if fresh Stereum is
added to that in the dish, the plasmodium will leave the
glass to form a dense layer over the fresh food.
When the plasmodium is spread on the glass this may
be raised a little above the edge of the dish by placing a rod
under the glass at each side ; this measure will allow the
plasmodium to dry slowly. As it dries it shrinks to form a
sclerotium. After a day's gradual drying the glass may be
removed and the sclerotium dried completely. It can then
be scraped from the glass in flakes like shellac and kept dry
for future use.
Sporangia. There is a wide range of form in the sporangia
of some species : thus in Physarum nutans and Didymium
squamulosum stalked and sessile sporangia and vein-like
plasmodiocarps are often formed from the same plasmodium.
The elements of which Fig. 42 is made up are parts
chosen from seventy-seven double plates in the first edition
of A. Lister's book. The plates are collotype reproductions
of water-colour camera drawings. The small portions here
150
PROTESTS AND DISEASE
42. VARIOUS SPORANGIA. 1, Sporangium, Didymium difforme x 20, part of the
outer membrane removed ; 2, Capillitium of the same X 280, the fibres have
nodes and are dichotomous ; the thickened margin of the base passes into the wall
of the sporangium ; 3, Didymium Clavus, sporangia X 20 : 4, Didymium nigripes
(xanthopus), sporangia, a, intact, b, broken open, showing the white columella ;
5, Didymium complanatum, plasmodiocarp, X 2 ; 6, section of the same X 80,
showing capillitium and large vesicles ; these are filled with yellow obscurely granular
matter, and are peculiar to this particular species ; 7, Cribraria languescens (United
States) sporangia after dispersion of spores x 20. After A. Lister.
THE MYCETOZOA 151
shown I copied by making tracings, and transferring these
to cardboard. In the process much of the delicacy of the
originals has been lost. Miss G. Lister very kindly gave me
permission to use this illustration.
Those who desire to appreciate fully the morphology
of Mycetozoa should study A. Lister's monograph, 2nd
edition, revised by Miss G. Lister, 19.11.
Further morphological details. The elements in Fig. 43,
represent types, for the most part as diagrams, based on the
works of A. Lister, A. de Bary, T. H. MacBride, and others ;
they are not intended to be accurate copies, and to some I
have added features to illustrate certain points. Readers
will, I hope, be led to consult the original documents. The
degree of magnification varies : small designs placed at the
side of larger ones, 9 and 77, are only a trifle above the
natural size. Spores and capillitium are shown magnified
about 300 times. In Badhamia (named after Badham, an
English mycologist) lime granules pervade the whole capil-
litium, whilst in other Physaraceae the lime granules are
limited to expanded parts of the capillitium, as in 2, 3, 4,
and 5, and to parts or the whole of the Sporangium wall.
In Diderma, 6, one genus of the Plrysaraceae, the capillitium
is devoid of lime-knots, but the outer of the two layers of
the sporangium w r all contains granules of lime. In Diachaea,
7, the stalk and columella are charged with lime, which is
absent from the purple capillitium. Of Lycogala, three
unequal aethalia (copied from A. Lister's book) and part of
r
>. 43. MORPHOLOGICAL DETAILS OF MYCETOZOA. 1, Badhamia macrocarpa ; 2, Physamm
nulans ; 3, Craterium minutum ; 4, Leocarpus fragilis ; 5, Fuligo septica ; 6, Diderma
testaceum ; 7, Diachaea leucopoda : 8, Mucilago spongiosa ; 9, CcmatricTia typhoides ;
10, Comalricha nigra ; 11, Cribraria vulgaris ; 12, Diclydium cancellalum ; 13, Orcadella
operculata ; 14, Tubifera ferruginosa ; 15, Lycogala epidendrum ; 16, Trichia varia ;
17, Arcyria incarnata, Made diagrammatic from various sources mentioned in the text.
THE MYCETOZOA 153
the convoluted early sporangium and the capillitium tubes
perforating the inner wall of the fully formed sporangium
(from de Bary) are shown in 15. A cursory view of the
illustration as a whole may leave the impression of a number
of apparently unrelated structures, but if what has been
stated in this chapter is kept in mind, the diversity is not
inexplicable. Details given in Fig. 41 show that before
spores are formed the protoplasm of Mycetozoa separates
into two distinct substances. The first, to use in a particular
sense a term employed by Lionel Beale, we may call Bio-
plasm ; the other part destined to form the supporting
structures may be called Skeletoplasm. The bioplasm is
used for the formation of the spore contents, and, with one
queried point, it is nucleated throughout. The skeletoplasm
from the beginning of sporangium-formation is, I think, in
the chromidial condition ; from it the capillitium as well as
other parts of the skeleton are formed.
It is easy to understand structural diversity if a Myce-
tozoon such as Comatricha nigra, 10, is studied. The series
of sporangia were drawn from nature. At first a sticky
sessile white bead, the sporangium soon becomes elevated
on a brown stalk, which can be seen to be prolonged as the
columella, owing to the transparency of the substance of the
young sporangium. The latter next becomes opaque and
of a glistening black ; a state which lasts but a short time :
the sporangium wall is evanescent and leaves a dull dark
brown surface when it disappears. A portion of this surface
154 PROTESTS AND DISEASE
(X370) is shown, 10, to consist of capillitium fibres, in which
four spores are supported, but no trace of a membrane is
present.
If the rising sporangia of Comatricha instead of growing
perpendicularly were to grow interwoven in all directions
and fused together an aethalium such as that of Fuligo, 5,
or other similar form, would be the result. When the
skeletoplasm is used entirely in the formation of coherent
sporangium walls a condition like Tubifera, 14, ensues.
The quaint genus, Orcadella, 13, is still more easily derivable
from the type of a Comatricha ; and, without its stalk and
with its lid replaced by a less definite form of dehiscence, it
would become like a Licea, which has the simplest sporangium
of all the Mycetozoa.
CHAPTER IX
ACRASIEAE : AFFINITIES AND PHYLOGENY OF MYCETOZOA, &C.
THE Acrasieae are a very small group made for organisms
which were formerly included in the Mycetozoa of de Bary.
In zoology they are termed Pseudo-plasmodida (Delage) to
distinguish them from the Euplasmodida or Mycetozoa
proper. They have also been called Sorophora.
The only state in which they are visible to the naked
eye is when they have formed spore-clusters, which resemble
small mycetozoan sporaiiges : round, and about the size of
pins' heads, or, sometimes streak-like; they are white, red,
or yellow in colour.
With the exception of Acrasis, which grows on the yeast
of beer, the known species live on decaying vegetable matter
and the dung of the horse and the cow.
They begin their career by hatching from a spore-case
as amoebulae ; they do not develop a flagellum, but creep
like amoebae.
They are depicted by Brefeld with short pointed pseudo-
podia. They have also a nucleus and a contractile vacuole.
Once hatched they multiply rapidly by simple division.
155
156 PROTISTS AND DISEASE
When nutritive material is used up, so states van Tiegham,
the myxamoebae converge on certain centres and become
apposed without fusion ; each such aggregation erects itself
perpendicularly, the elements climbing over one another to
take characteristic shape in a spore-apparatus. The long
plasmodial stage accompanied by growth seen in the
Mycetozoa is wanting in the Acrasieae.
Spores are constituted by encapsulation of separate
FIG. 44. DIAGRAM OF STAGES OF ACRASIEAE. 1, a, Amoebula ; 6, binary
division of same ; c, false plasmodium (cohesion without coalescence) ;
d, formation of sorus and spores. 2 } Stage in sporangium-formation
in the Dictyostelidae massed amoebulae of which the innermost are
transformed into a skeleton up which the rest climb.
amoebulae in the aggregations. They are held together by
glutinous material. There is no sporangia! membrane like
that of the endosporous Mycetozoa ; van Tiegham compares
them in this respect to the exosporous Mycetozoon, Cera-
tiomyxa, Fig. 45, 6 to 11.
In unfavourable surroundings the myxamoebae form
protection- cysts, which may be two or even three-fold in
Guttulina.
ACRASIEAE
157
11
13.
. 45. 1 to 5, ACRASIEAE ; 6 to 13, THE EXOSPOROUS MYCETOZOON, CERATIOMYXA
FRUTICULOSA. 1, Sappinia pedata (Dang) cysts ; 2, the same, single element
encapsuled ; 3, Copromyxa protea (Fayod) sorus ; 4, the same, amoebula escaping
from spore-case ; 5, Polysphondylium Brefeldi, a, 6, c, d, stages in the formation of
sorus, which is branched, from massed amoebulae from Doflein after Olive and
Brefeld ; 6, 7, and 8, stages in the formation of sporophores in Ceratiomyxa ; 9, the
same X 40 ; 10, the same x 480 ; 11, the same, cells on surface, some being modi-
fied into spores, x 120 ; 12, a, b. c, d, e, stages in hatching, and subdivision of spore
and formation of zoospores, x 1200 ; 13, young sporophore showing plasmodial net
in process of forming the cellular surface of the sporophore the hyaloplasm is
drawn thicker than in the original, x 68. 6 to 8, After de Bary ; 9, 10, and 12, after
A. Lister ; 11 and 13, from de Bary after Famintzin and Woronin.
158 PROTISTS AND DISEASE
Copromyxa (Zopf) would seem to be a variety of Guliu-
Una : both are of milky aspect and produce sessile round,
or club-shaped colonies, Fig. 45, 3.
Sappinia pedata (Dang), Fig. 45, 7 and 2, affords the
simplest example of this type of organism : the amoebulae
become encysted separately, on straws and the like. They
do not appear to form a pseudo-plasmodium.
In Acrasis the amoebulae form a vertical row. The
lower and larger cells are transformed into thick-walled
strongly adherent cellulose cubes full of clear liquid, the
rest of the amoebulae arrange themselves in chaplet-form
at the upper end and become spores.
In Dictyostelium a similar differentiation takes place
but the supporting cellulose column, Fig. 44, 2, may be
composed of many rows of cells. De Bary compares the
stalk of Dictyostelium to that of Stemonitis.
Dictyostelium and Polysphondylium (Brefeld) differ only
in that the stalk of the latter, Fig. 45 : 5, a, 6, c, d, is
branched.
I have not been able to find living examples of this group.
The impression left by reading accounts of Acrasieae is that
much more remains to be learnt about them.
ACRASIEAE 159
Notes on some affinities of Mycetozoa
Watching living zoospores of any Mycetozoon under the
microscope we see them incept and digest bacteria, and we
see them divide, so that it would be easy to think that we
had before us a simple flagellate or monad.
Again we see a mycetozoan plasmodium incept whole
colonies of bacteria or other solids by its pseudopodia, and
digest them in vacuoles, so that we could well believe it to
be a rhizopod protozoon.
Examining the stages of spore-formation we cannot fail
to be reminded of the same process in a puff-ball, a synch y-
trian, or a sporozoon.
Mycetozoa have affinities with the vegetable protists
especially Chytridiineae on the one hand, and with the
animal monads, rhizopods, and sporozoa on the other hand.
The likeness that is seen on comparing the texture of
the protoplasm of chytridians with that of Mycetozoa has
often been remarked upon. The protoplasm of the thistle-
Synchytrium is very like that of many mycetozoan structures.
We may compare the sexual stages of Synchytrium to the
mycetozoan plasmodium, botli result from isogamy ; the
subsequent numerical increase in the synchytrian is by
generative chromidia ; in the mycetozoan by mitotic nuclear
divisions, such chromidial processes as I have observed
being chiefly for the production of capillitium elements.
The nucleus of Polyphagus euglenae is more like the
160 PROTISTS AND DISEASE
mycetozoan nucleus than is that of Synchytrium when in
mitosis, the former having 10 or 12 chromosomes, the latter
in the asexual sorus of 8. endobioticum, only 5.
The conjugation of similar zoospores to form the myce-
tozoan plasmodium is an algal trait, which is found also in
some monads. We may compare the growth of the synchy-
trian zygote with that of the plasmodium of a parasitic
form more justly perhaps than with free-living myceto-
zoa. The synchytrian grows by chromidial or plasson
extensions from a nucleolus to form what is really a plas-
modium limited in extent by a cell- wall. Plasmodiophorans
grow by nuclear divisions, the chromidial phase being
assumed as a brief stage after growth is complete. Zygote
formation has not as yet been seen in them.
The Animalia monadida fall into two groups, Acra-
spedina and Craspedina, according as the flagellum has
not, or has, a collar (Gr. kraspedon) round its base. The
Monadida Acraspedina include free-living forms such as the
Rhizomastigina, of which a phase of one species, Mastigella
vitrea, has been mentioned in Chapter I ; together with
many parasites, such as, of blood-parasites, the genus
Trypanosoma (see Part I), causes of sleeping-sickness, &c. ;
tissue-parasites, such as Leishmannia donovani, the cause of
black-fever and splenomegaly (see Part II) ; and innumer-
able intestinal parasites such as Copromonas subtilis of the
frog.
Two monads described by Cienkowsky, M. parasitica
ACKASIEAE 161
and M. amyli, have a course of life that approaches that of
Mycetozoa very closely.
The convincing resemblance that the mycetozoan plas-
modium bears to rhizopods needs no emphasis. The absence
of mention of chromidia in most accounts of Mycetozoa
might be regarded as pointing to an essential difference, but
chromidial features which I found in Didymium difforme
(Part IV) remove some of this seeming distinction.
Of all Sporozoa, the Haplosporidia ; that heterogeneous
group founded by Caullery and Mesnil in 1899, are the most
likely to furnish examples of kinship to mycetozoa. One
haplosporidian, Schewiokovella schmeili, a parasite of cope-
pods, has an unsporozoan character in the presence of a
contractile vacuole, and a mycetozoan character in that the
young animals sometimes fuse into a plasmodium, which
becomes encysted and subdivides into spores. Another
Haplosporidian, Ehinosporidium kinealyi, is the cause of
infective tumours in the nasal fossa and other parts of the
human body. In this species also, as is shown in Part IV,
there is evidence of a contractile vacuole at one stage, while
at another stage the parasite assumes a chromidial or even
a plasson state.
From some simple alga or alga-like fungus such as
Aphragmium (p. 35) may have evolved both Acrasieae and
Mycetozoa.
11
162 PROTISTS AND DISEASE
A Note on the Basis of Classification of the Phycomycetes
and the Mycetozoa
The name Phycomycetes or alga-like fungi was made by
de Bary to include forms like Saprolegnia, Pythium, and
Peronospora. It has since been extended to embrace the
Chytridiineae.
The systematic arrangement of the Mycetozoa has to be
viewed from two different aspects, the botanical and the
zoological respectively.
A complete modern classification of the Phycomycetes
was given by J. Ramsbottom in the Transactions of the
British Mycological Society, Vol. VI, Part II, 1916.
The subjoined zoological classification of the Mycetozoa
is that given by Delage and Herouard, Zoologie Concrete,
Tome I, 1896.
PHYCOMYCETES =00 M YCETES + Z YGOM YCETE8.
OOM yC^mS=CHYTRIDIINEAE 4- ANCYLISTINEAE +
MONOBLEPHABIDINEAE -f SAPROLEGNIINEAE
+ PEBONOSPORINEAE.
Z YGOM YCETES=MUCOItiNE AE + ENTOMOPHTHORI-
NEAE.
CHYTRIDIINEAE =MYXOCHYTRIDIINAE + MYCOCHYTRIDII-
NAE.
ACRASIEAE 163
MYXOCHYTRiDiiNAE=01pidiaceae+Synchytriaceae.
MYCOCHYTRIDIINAE =Rhizidiaceae + Cladochytriaceae.
Olpidi&cQ&GOlpidium+Olpidiopsis+Pseudolpidium + Pleol-
pidium, &c.
Synchytriaceae = Synchytrium.
Synchytrium=(PycnochytTidi)=S. anemones -{-8. aureum,&,c. +
(Eusynchytria) =S. taraxaci +8. succisae +8. endobioti-
cum+S. stellariae, &c.
Botanical.
MYCETOZOA ** PLASMODIOPHORACEAE + ACRA-
SIEAE + M YXOM YCETES (M YCETOZOA of de Bary).
Zoological.
TtiiIZOPOT>A.--=PEOTEOMYXA + MYCETOZOARIA +
AMOEBINA + FORAMINIFERA + HELIOZOA +
RADIOLARIA.
MYCETOZOARIA = PSEUDOPLASMODIDA (ACRASI-
EAE) + FILOPLASMODIDA (LABYRINTHULEA) +
EUPLASMODIDA (MYXOMYCETES or MYCETO-
ZOA of de Bary).
The position of the Plassomyxineae must be next to the
Synchytriaceae, and near the Plasmodiophoraceae.
CHAPTER X
NOTES ON SMALLPOX, SYPHILIS, CANCER, ETC.
Cystic disease of the urinary tract. Sometime before 1892
representative London pathologists had sought the opinion
of T. Spencer Cobbold upon some microscopic bodies found
in two instances of disease ; one of these was a condition
similar to that of which some details are shown in Fig. 46.
Cobbold pronounced the bodies to be " psorosperms,"
meaning that they were sporozoa of some sort. This opinion
was accepted by English pathologists. The fullest account
of my case is in Part II, where the difficulty I had in adopting
the accepted view is explained. When I realised that it is
parasites one sees in those cysts, Fig. 46, 1, I did not think
I was merely in presence of a rare disease, which by reason
of its rarity would, in itself, have the less importance for
mankind ; but I felt that what I was studying was probably
a rare manifestation of several common diseases, such as
some forms of kidney-disease, papillomas of the bladder,
and adenomas of the prostate.
Last year for the first time I saw Cornu's illustrations
of Olpidiopsis ; some of them are suggested in Fig. 15, p. 60.
164
SMALLPOX, SYPHILIS, CANCER, ETC. 165
Here for the first time in biological literature I saw some-
thing relating to organisms of the same category as Cobbold's
psorosperms.
Can one identify the cyst-contents of this disease with the
Olpidiaceae ? There are two difficulties ; firstly, the cytology
of such olpidians as Rozella septigena &c. that appear to form
7
FIG. 46. CYSTIC DISEASE OF THE URINARY TRACT. Section of a cyst
in the pelvis of the kidney under a low power, showing the general
character of the cyst-contents. At a is an invagination of the mucous
membrane, as if preparatory to formation of a new cyst (from Part II) ;
2, parasited with a nucleus of fragmented chromatin ; 3, ibid, with
a well-formed nucleus ; 2 and 3, x 1000 diams., from the Trans.
Path. Soc. 1892.
plasmodia with one another or with host-cells has not been
fully established ; secondly, the cystic disease has only been
examined 24 hours or more post mortem. At present we
can hardly assign a definite place in taxonomy to the
parasite.
All known Olpidiaceae, whether they form plasmodia
166 PROTISTS AND DISEASE
or not, produce zoosporangia. Now, though there is evidence
of the formation of capsules round some of the oval bodies,
reproduction in the cysts is chiefly by plasmodia subdividing
directly into amoebulae, a fact that suggests the Plasso-
myxineae as their proper group ; but early intracellular
stages not being traceable, the classification must be un-
certain until more information is available.
An organism recognised in pathology for over 30 years
should have a name and without prejudice to future identi-
fication with some parasite previously described, I would
suggest Olpidiiforma cobboldi as the name of the causal
parasites of cystic disease of the urinary tract.
A false analogy. With respect to the parasites of cancer
&c. the position I have maintained is that they are of
kindred nature with those of cystic ureteritis. Several
observers identified them with coccidia. This Coccidium-
idea was successfully opposed by Fabre-Domergue and
others. Their task was a very easy one, that of destroying
a false analogy, a very different matter from disproving the
fact that the bodies in question are parasites.
Virchow compared the bodies of molluscum contagiosum
with C. oviforme and finding no clear correspondence decided
illogically that the bodies must be altered epidermal cells,
a decision that is accepted in pathology to-day.
That earnest pioneer, L. Pfeiffer, making the same
comparison on other grounds, decided that the virus must
be concealed in the interior of the molluscum body and thus
SMALLPOX, SYPHILIS, CANCER, ETC. 167
was laid the foundation of the delusive Chlamydozoa-
theory of von Prowazek.
Again, in an article published in the British Medical
Journal, 10th Dec. 1892, Metchnikoff left the impression
that he regarded as coccidial the bodies described by Souda-
kewich in cancers. In the next issue appeared a letter of
mine stating that they are not coccidia " in the biological
sense of the word."
At the present time one investigator writing with seeming
indifference to the history of the subject, and apparent
neglect to examine epithelial lesions, claims Cytoryctes luis
as a Coccidium.
This protozoon has had such a disastrous effect on
pathology that I am almost ashamed to have given the
first description of its early microgametogenesis.
The sporozoa idea not only diverted me from the right
path but also led me into error ; thus in 1893, in the course
of an examination of an adenoma of a cat's lip among the
sections of the tumour which show cysts that contain bodies
like those of cystic ureteritis, another of a seminal vesicle
of an earthworm found its way, probably from the razor
of the microtome. Too keen on the mistaken trail of
Sporozoa it was this particular section that, not suspecting
what it was, I chose to show at a meeting of the Pathological
Society, arid a drawing of it disfigures p. 93 of my " Morbid
Growths and Sporozoa."
So long as I accepted Olpidiiforma and kindred bodies
168 PROTISTS AND DISEASE
as sporozoa I was studying fungi and calling them protozoa
all the time, i.e. for nearly 30 years ; and this has been the
case generally, with the result that we have importuned
protozoologists for enlightenment, which could only have
been given us by cryptogamic botanists.
Smallpox
Guarnieri's experiment. Twelve hours after inoculation
of a scratch in the corneal epithelium of any rodent with
smallpox or vaccine lymph minute foreign bodies can be
found close to the nuclei of the epithelial cells. With the
point of a sharp knife or needle a linear scratch is made
vertically across the cornea through the epithelium without
incising the fibrous layer. At the desired time the animal is
killed, the eyeball excised and placed at once in the fixing
fluid, or scrapings can be made for immediate examination.
This is Guarnieri's experiment.
After 24 hours the corpuscles are larger and the experi-
ment can be used for diagnosis, scrapings showing the bright
greenish bodies clearly. At this stage sections show that
the bodies in cells close to the incision are larger than those
farther away, those in cells next the apparently uninfected
ones being very small, many of them subdividing by fission.
At the end of 48 hours the bodies are very obvious and
in well-stained sections show very clearly as in Fig. 47.
They stain well with methylene blue and with haematoxylin
and eosin, taking the basic and acid stains about equally.
SMALLPOX, SYPHILIS, CANCER, ETC. 169
Mitoses in epithelial cells. -In good sections at this
stage in a narrow zone separated by a definite interval from
the area in which the parasites are visible the epithelial cells
are swollen and many of them are in mitosis. The cells
occupying the interval between the advanced line of visible
parasites and the active epithelial cells probably contain
FIG. 47. A PORTION OF THE EPITHELIUM OF A RABBIT'S CORNEA FORTY-
EIGHT HOURS AFTER VACCINATION. Guarnieri's bodies are seen as
roundish dark objects near the nuclei of the epithelial cells. From
a photograph of one of the Author's preparations made in 1894.
H. and E. x 400.
parasites in the microhenad stage and the activity of the
cells is defensive.
Variations in the parasites. Though they look quite
different the two sets of elements shown in the two parts of
Fig. 48 represent the same fact, the passage of the parasites
170 PROTISTS AND DISEASE
from the pycno- to the chasmatoplasson state with the
appearance of chromatin, repeating stages of the thistle-
Synchytrium previous to its subdivision into zoospores.
Such forms as those in Fig. 48, 1, are hard to find because
parasites as they mature fall off with their host-cells. In
some of the elements of Borrel's drawings, e.g. Fig. 48, 2,
beside remains of unchanged dense substance are definite
small nuclei. It must surely be obvious that bodies capable
of producing nuclei from a previously akaryote state have as
much claim to be regarded as representing organisms as
others which have nuclei all the time. This has been the
basis of my position since 1892 when I found evidence of
new nucleus-formation in the olpidiiform bodies in cysts of
the ureter and in cancer.
Cytoryctes the cause of vaccinia. Once the Cytoryctes
is recognised as a parasite its pathogenic quality cannot be
doubted by any who have made a long and careful study
of infected corneas on successive days.
Borrel ascribed them to leucocytes, but his own careful
drawing, Fig. 48, 2, a, suffices to negative this explanation.
His words, " Pour caracteriser un protozoaire il faut un
noyau," show that, as it was with the rest of us at that
time, the possibility of parasites other than protozoa had not
occurred to him.
In his many studies of variola and vaccinia L. Pfeiffer
was also handicapped and his work frustrated by the fatal
protozoon-idea. The likeness of Cytoryctes to some stages
SMALLPOX, SYPHILIS, CANCER, ETC. 171
of sporozoa is very great. Pfeiifer was the first to point
this out, and in 1887 he named the parasite, " Monocystis
epithelialis," after the gregarines of the earthworm.
FIG. 48. ELEMENTS FROM VACCINATED CORNEAS, 1 (from Path. Soc.
Trans. 1895), guinea-pig's cornea 3rd day ; a, two epithelial cells,
one containing a parasite, and three free parasites ; b, Cytoryctes with
central clearing containing chroma tin ; c, ibid, with three mitoses ;
d, ibid, with chromatin in nuclear form ; e, parasite with scattered
chromatin granules and a separated segment ; /, ibid, subdivided
into nucleated segments. 2 (after A. Borrel, 1903), rabbit's cornea
8th day ; all the epithelial cells contain Borrel's " pseudoparasites,"
really Cytoryctes passing from pycno- to chasmatoplasson state with
the appearance of small nuclei ; a leucocyte at a.
172 PROTISTS AND DISEASE
Spirochaetes in vaccinia. In the vaccine vesicle spiro-
chaetes have been found by Bonhoff, 1905. Many details
remain to be worked out, but enough has been established
to show that Cytoryctes guarnieri belongs to the same group
as Plassomyxa contagiosa.
Intranuclear phases of Cytoryctes. In smallpox about
the same time Bosc in France and Councilman and others
in America described the intranuclear forms of the parasite,
the presence of which explains the difference between the
clinical courses of the two modifications of the disease : in
vaccinia the stages of Cytoryctes variolae are found only in
the cytoplasm of host-cells as in Fig. 49, 1 to 5 ; in smallpox
that stage also occurs and is repeated many times before
the distinguishing intranuclear generation appears, Fig. 49,
6 to 9.
In 1904 Professor Calkins very kindly gave me some
sections of smallpox pustules stained by Borrel's indigo-
carmine picric acid method ; these sections show the intra-
nuclear stages to-day as clearly as when they were given to
me. Many of the minute subdivisions have left the nuclei
and are scattered in the sections. More observations on
fresh material are desirable to find out if they are the heads
of flagellates such as were described by Doehle in 1892.
The first interpretation of the whole series of forms was
that Cytoryctes was a sporozoon ; later, after chromidia had
been generally recognised, Cytoryctes was thought to be a
Rhizopod ; finally after Dangeard's discovery of Nucleophaga
FIG. 49. CYTORYCTES VARIOLAE, GUARNIERI. 1, A cell from a section
of a smallpox lesion : three amoebulae are present in the cytoplasm
close to the nucleus ; 2, a cell containing an older amoebula in the
cytoplasm ; 3, a cell containing a large amoeboid parasite in the
cytoplasm ; 4, a cell containing an amoeboid parasite in process of
amoebula-formation, and, above, a round dense body, probably a
microgametocyte ; , a cell containing an amoeboid parasite in process
of gemmule-formation : some of the amoebulae are escaping into the
cytoplasm ; 6, a cell the nucleus of which contains five spores and
three secondary sporoblasts developed from spores : there is one
spore in the cytoplasm ; 7, a cell the nucleus of which contains
secondary sporoblasts ; 8, a cell the nucleus of which contains a
reticular sporoblast, with spores, some of which have escaped from
the meshwork ; 9, a cell the nucleus of which has been replaced by a
large sporoblast, from which some of the spores have escaped into
the cytoplasm. Copied from the coloured plates illustrating G. N.
Calkin's section of " Studies of the Pathology and on the Etiology of
Variola and of Vaccinia," published in the Journal of Medical Research,
1904.
c
FIG. 50. NUCLEOPHAGA AMOEBAE. A, normal Amoeba verrucosa, n,
nucleolus ; B, Amoeba of which the nucleolus, ri, contains a Nucleo-
phaga which has a central nucleus and a pale cytoplasm ; C, Amoeba,
the nucleus of which is replaced by a Nucleophaga, and which is
incepting an encysted Euglena ; D, Amoeba the nucleus of which is
replaced by 3 ripe sporanges of Nucleophaga ; e, nucleus of Amoeba
verr. showing the perforation in its membrane by which entered the
Nucleophaga it contains ; /, host-nucleus filled by three young
sporanges ; g, sporange as seen in the living state ; h, sporange stained
showing nuclei, one of these on larger scale above. After P. -A.
Dangeard.
SMALLPOX, SYPHILIS, CANCER, ETC. 175
had been digested in zoology Calkins (1909) wrote of
Cytoryctes : " There is no doubt, however, that the parasite
is a species of nucleophaga, and the name karyoryctes
must go."
x-^ MXi'^y&
FIG. 51. KARYORYCTES. a, various stages in the macronucleus of a
Paramaecium ; b, spore -formation begins ; c, spores formed, four
escaped into host's substance ; d, group of spores ; e, amoebula-
formation, below, " residual body " ; /, reticular body containing
points of chromatin. After G. N. Calkins.
Nucleophaga and Karyoryctes. Now we must consider
the question left over from Chapter III as to the position of
the parasite described by Dangeard in 1895 under the name
of Nucleophaga^ and as to its being homologous or not with
176 PROTISTS AND DISEASE
the parasite Karyoryctes found by Calkins in 1904 in the
macronucleus of Paramaecium aurelia.
Some of Dangeard's illustrations are shown in Fig. 50.
The parasites enter the nucleolus of their host, Amoeba
verrucosa. They have obvious nuclei from the first. In
the grown parasite, d, the nuclei are of fungal type and are
like those shown in Olpidiopsis in Fig. 16, e. The spores are
liberated by disintegration of the remains of the host-
karyoplasm ; this occurs only when the parasite has com-
pleted its development. Dangeard concluded that Nucleo-
phaga is a vegetable rather than an animal protist because
it leaves no food-remains.
Turning now to Karyoryctes as shown in Fig. 51, the
young parasites as in c and d have no centrally placed
nucleus, but a thickening at the side which gives a " signet-
ring " look. The spores as shown at a germinate by forming
a vacuole and the protoplasm grows into it in plasmodial
form, still without nuclei. Another mode of reproduction
in Karyoryctes, e, is not seen in Nucleophaga, but is similar
to that shown below, Fig. 54, 18, 19, in a Plassomyxa of a
sarcoma. The reticulate body, /, was also termed residual,
but its points of chromatin recall the chromidial stage of
the direct sporangium of Synchytrium.
No two related protists could well be less alike than
Nucleophaga and Karyoryctes : the former is a Chytridian,
the latter one of the Plassomyxineae.
The accomplished protozoologist has done better than
SMALLPOX, SYPHILIS, CANCER, ETC. 177
his later thought allows, having discovered in freshwater
protozoa a species of vegetable protist, which may be found
to play an important part in some human pathological
processes. Another organism, Lymphosporidium truttae, was
also discovered by Calkins (see Part I, pp. Ill to 115).
The mode of reproduction seen in Fig. 51, e, was the only
one found ; this organism also would appear to be a Plas-
somyxa.
The stages of Karyoryctes described by Calkins corre-
spond only to the intranuclear stages of Cytoryctes variolae.
Is there another intracytoplasmic cycle in the same or another
animal, or even in man ? Among tumours goitre is associated
with certain water-courses, and in goitres intracytoplasmic
cell-inclusions resembling Cytoryctes variolae occur.
Syphilis
Parasitic forms occurring in Syphilis. In 1892 flagellates
were described by Doehle as they had been found by him in
the blood of patients suffering from syphilis, smallpox,
vaccinia, measles, and scarlet fever.
My own first aim was to see whether the parasite of
syphilis conformed to the type Cytoryctes variolae. On the
3rd day after inoculation with the exudation of a chancre
I found in the corneal epithelial cells of a rabbit bodies
comparable to the early state of Cytoryctes variolae.
Cell-infiltration by leucocytes and young tissue-cells
obscured the view in my sections of chancres. At that time,
12
178
PROTISTS AND DISEASE
1894, any spreading sore that resisted the oral administration
of mercury was excised. I thought that near the margin of
rapidly spreading secondary ulcers the parasites would be
found in epithelial cells just in advance of the leucocytes :
ny^ *
FIG. 52. PART OF THE EPIDERMIS IN A SECTION OF A SPREADING
SECONDARY SYPHILITIC ULCER, a, Horny layer ; b, normal nucleus
of epidermal cell ; c and d, nuclei of epidermal cells that are breaking
up ; u, v, w, x, y and z, various stages of the bodies described as
protozoa by the author in 1895. Two leucocytes are present among
the minute bodies at z. Reduced from a drawing made with drawing
eye-piece and yinch oil-immersion lens. From Part II.
this proved to be the case as shown in Fig. 52. In the section
are seen large pycnoplasson parasites ; these are linked by
stages to others breaking up into minute nucleated elements :
only when this subdivision occurs do the parasites attract
leucocytes as at z.
SMALLPOX, SYPHILIS, CANCER, ETC. 179
In 1905 Siegel described flagellates, which attained their
maximum number in the second and third weeks of syphilis.
His drawings show round and bluntly crescentic bodies
about 2fji with a single flagellum ; the latter was difficult to
discern in fresh preparations. Similar bodies were found in
thin (2 p.) sections of chancres, where the larger bodies were
seen inside, the smaller between the connective-tissue cells.
In rabbits and guinea-pigs inoculated with syphilis the same
bodies were found in the blood and tissues.
Later in the same year Schaudinn in the course of an
investigation of Siegel' s observations discovered the mobile
form, which he named Spirochaeta pallida. His view,
stated in Part II, that this was an organism homologous
with Leucocytozoon ziemanni, a blood-parasite of owls, has
proved to have been formed too hastily.
Spirochaetes. In 1838 Ehrenberg discriminated between
the genus Spirochaeta with flexible bodies and the genus
Spirillum with rigid bodies. The best-known spirochaetes,
e.g. S. balbianii of the oyster's alimentary tract, have blunt
ends and an undulating membrane : 8. pallida on the
contrary has taper flagellum-like ends and no membrane ;
hence Schaudinn altered the name to Spironema pallida.
This later name will be used here as it was in Part II.
In 1911 Noguchi obtained anaerobic cultures of the
spironema in broth containing fresh kidney. Later the
medium was changed to white of egg in ascitic fluid broth
under paraffin. In some cultures the organisms are thicker
180 PROTISTS AND DISEASE
than in others, and different strains cause different lesions
in the rabbit. Noguchi found the spironemes not to be
filtrable, but they grow through a filter in 4 days. Both
longitudinal and transverse divisions have been observed
in the spironeme.
One can understand how those who study syphilis only
by seeking spironemes for diagnosis, 1 and reflecting on the
cultural results just mentioned conclude that the spironeme
is to syphilis what Koch's bacillus is to tuberculosis.
In order to accept this simple interpretation of syphilis
one must ignore the intracellular and other phases mentioned
above ; indeed many more proved facts than can be
explained by accepting Schaudinn's view.
The spironema is not a final phase : like other similar
bodies it has been observed to shed granules which appear
to be the immediate infecting agents. Of all accounts of
granule-shedding the most complete is that given by
A. Balfour as he saw it in spirochaetosis of Soudanese fowls :
the granules were forced out by repeated contractions of the
skin-layer. The question does not concern syphilis alone :
spiral forms occur in Plassomyxa contag. and in probably
the same parasite in flagellate-diphtheria of birds ; they
have been found in vaccinia, and in some tumours mentioned
below. The conditions of cultivation that suit the spiro-
nema are uniform ; such as would be likely to favour one
1 Examination by help of the dark-ground illumination microscope is now regularly
used in clinical work, and it is of the greatest service : early diagnosis and immediate
treatment being now the rule.
SMALLPOX, SYPHILIS, CANCER, ETC. 181
phase of a polymorphic organism, in the same way that
grape-sugar solutions favour the gemma-stage of Mucor
racemosus.
The parasite of syphilis and Synchytrium. It has been
shown in Chapter V that bird's-eye bodies occur in Synchy-
trium and in syphilis as well as in cancer. The series of
stages seen in Fig. 52 is almost identical with those of the
direct sporangium of the thistle- Synchytrium, Fig. 23 :
pycnoplasson, chasmato-plasson, &c. Looking again at
Fig. 52, z, and comparing it with the stages of Synchytrium
we should expect the succeeding stage of the parasite of
syphilis to be flagellate, and such I have no doubt is the
case. In S. endobioticum three different flagellate phases
occur. It may be that the monoflagellates of Siegel are the
zoospores, and the biflagellate spironeme the zygote of the
parasite. It seems to me that the most promising line of
inquiry to clear up the questions of the relation of the
spironeme to the other parasitic forms in syphilis and
other diseases is through the study of flagellate-diphtheria
of birds, combined with such study of syphilis as was well
begun in 1906 by MacLennan.
Gummata. With regard to the histology of the gumma,
in 1895, I stated my opinion that much of the broken-down
material consists of parasites in a state of fatty degeneration
and compared them to similar bodies in cancer, e.g. in the
sarcoma of the testis, Fig. 31, in M.G. and S., also Part II,
Figs. 41 and 42.
182 PROTISTS AND DISEASE
Syphilis and Cancer. The identity of some intracellular
parasitic forms in late syphilis with those of cancer has been
shown above in Chapter V, where the production of " cells
of endogenous origin " in living parasites of a late syphilitic
lesion is described.
Clinical phenomena only too familiar to us express the
same fact in another way.
We know that typical syphilitic differ from typical
cancerous lesions in certain features, but where syphilitic
glossitis is becoming changed into cancer these differences
are very gradually acquired, and it is not possible either
clinically or pathologically to say at what moment one
disease becomes converted into the other. Parasitic protists
are equally abundant in both, and they appear to be a series
of phases of the same parasite. I do not mean to say that
all cancer is a modified form of syphilis, but as far as can be
seen it is so in this particular instance. Probably cancer is
produced by as many different species of protists as there
are different bacteria, etc., that cause chronic granulomas.
Cytoryctes Luis. I have no doubt that Cytoryctes luis
(Siegel 1905) is the right name for the causal parasite of
syphilis. This designation accords with all the facts ascer-
tained up to the present, and, although when Siegel invented
the name he does not appear to have known of my observa-
tions (1894), these alone would sufficiently warrant his
choice.
SMALLPOX, SYPHILIS, CANCER, ETC. 183
Cancer
In pathology the term cancer is applied to a malignant
tumour which originates in epithelium such as the epidermis,
or mucous membranes such as the lining of the mouth, the
stomach, or bowel ; or the epithelial part of a gland such as
the liver. A sarcoma is a malignant tumour that originates
in one or other of the connective-tissues : fibrous tissue,
bone, &c. We may think of these two phases of disease as
epithelial cancer and connective-tissue cancer respectively.
Cancer affords greater opportunities for investigation
than almost any other disease : its dread plenty, long
course, and the frequent calls for operation furnish material
only too abundant. Added to this the facility with which
cancer can be grafted into mice gives those who have sanction
opportunity for unlimited observations. Of the countless
experiments that have been made with Jensen's mouse
cancer the result obtained by Ehrlich and Apolant is the
most important : on transplantation epithelial cancer be-
came sarcoma, showing it cannot otherwise be explained
that the two diseases are one, and that both are caused by
the same parasites.
Parasites of a Connective-tissue cancer. Photographs
of a sarcoma of the breast are reproduced in Fig. 53. A
detailed account of this tumour having been given in Part II,
only the chief features need be noticed here ; they demand
patient and minute attention.
184
PROTISTS AND DISEASE
The photographs were taken from E. H. B. -stained
sections as also was the coloured plate, frontispiece to
FIG. 53. THREE MICROPHOTOGRAPHS OF AN ALVEOLAR SARCOMA OF THE
BREAST. In 1 the parasite has absorbed part of the nuclear membrane
to which two of its tentacles are attached ; 2, a large intranuclear
parasite with knobbed tentacles, one spirally retracted ; 3, a nucleus
containing several parasites, and an extranuclear parasite sub-
dividing into stellate amoebulae. 1, x 400, 2 and 3, x 800 diams.
From Part II.
SMALLPOX, SYPHILIS, CANCER, ETC. 185
Part III. The description of the figures will serve for
explanation. Sections stained as just mentioned faded
quickly, but H. and E. -stained sections are still well stained
after 28 years.
It is to be noted that the tissue cells of this tumour are
ordinary connective-tissue cells. No epithelial cells were
seen in the parts of the gland that were affected by the
neoplasm.
The peripheral processes of the intranuclear bodies
were seen in the H-E-B. -stained sections better than in
sections stained in other ways. They stained a brownish-
orange colour, and many of them were seen to possess knobbed
" tentacles " like that in Fig. 53, 2. In the haematoxylin
preparations the ends of these processes, being stained like
the chromatin, are not so clearly seen.
Chromatin in and subdivision of parasites. In some
parasites, e.g. Fig. 54 ; 5, 6, and 13, chromatin is seen as it
had been streaming from the central part of parasites.
In others the chromatin consists of a single central
mass, or several such. Spindles of the ordinary characters
are present in some of these cells, and simple binary division
of the chromatin mass, with or without formation of definite
chromosomes, may occur in them, as in similar cells of other
sarcomas ; but in this tumour the result of this form of
nuclear activity was limited to the formation of the small
roundish bodies shown in 8 and 16. The cells 9 to 19 are
described beneath Fig. 54. A few words as to the formation
186
PROTISTS AND DISEASE
FIG. 54. ALVEOLAR SARCOMA OF THE BREAST. 7, Intranuclear parasite
attached to the nuclear membrane by a pedicle ; 2, parasite attached
to nuclear membrane by a group of short tentacles ; 3, parasite in
the cytoplasm of a connective-tissue cell ; 4, a free parasite assuming
SMALLPOX, SYPHILIS; CANCER, ETQ 187
of the small rounded bodies, which have already been con-
sidered as they arise from the flowing of cliromatin matter
along the spindle. In 15 is a cell containing two chromatin
masses. From the lower one of these a stream of chromatin
particles is passing into a limited area of the cytoplasm ;
and near the same chromatin mass are two rounded bodies.
Above is a second chromatin mass adjoining a round body
with slender peripheral rays. From long and close study
of the cells of this tumour I have no doubt that such round
bodies arise from the mixture of a chromatic and a non-
chromatic substance, and that they are minute amoebulae,
termed gemmules in Part II. Achromatic strands of linin are
seen in 8. Another mode of amoebula-formation is that
the amoeboid character ; S, a similar parasite with streaming of
chromatin from the chromidial central part ; 6, chromatin appearing
as a ring of filaments around a central chromidial mass ; 7, parasite
with central mass of chromatin and an irregular spindle a bud
forming to the right ; 8, similar to 7, but with several chromatin
masses and peripheral formation of " gemmules " ; 9, parasite with
basiphile chromatin in process of formation around oxyphile masses ;
10, same as 9 below, and a spindle with ordinary chromatin above ;
11, parasite with chromatin in foci somewhat resembling leucocytes ;
12, parasite similar to 9, but with basiphile chromatin in a network
enclosing three oxyphile bodies : such stages in the parasites simulate
nuclei of somatic cells ; 13, a parasite with radial moniliform chro-
matin ; 14, parasite with chromatin in a form resembling an irregular
spireme a " giant mitosis " ; 15, a parasite showing below the
formation of an amoebula by chromatin streaming into a localized
area, and elsewhere stages in amoebula-formation ; 16, a parasite with
multiple amoebula-formation at the surface : also a free amoebula
provided with tentacles, and four leucocytes ; 17, a parasite with
central amoebula-formation ; 18, a parasite from which gemmules
have been formed, and all but three have escaped ; 19, a reticulum
from which all the amoebulae have escaped. X 1000 From Part II
*r
J J_C d*J~. cl ' '*
FIG. 55. For description see opposite page.
SMALLPOX, SYPHILIS, CANCER, ETC. 189
shown in 16. The lobed chromatin body in this case was
translucent, probably from the chromatin being very finely
divided ; the linin system pervades the whole of the cyto-
plasm, making lines which converge at the points where
amoebulae are being formed. Near this cell are a free
amoebula and four leucocytes ; the latter are quite easily
distinguishable, and appear not to have been phagocytic as
regards the amoebulae, none of which are seen inside them.
Other modes of amoebula-formation are shown in Fig. 54.
To explain modes of subdivision the descriptions of
Figs. 54 and 55 will suffice for the average cases, but I invite
attention especially to Fig. 55 ; 12, and 15 to 19. In 12 a
parasitic mass is breaking-up into stellate amoebulae like
those seen in abundance in the mammary sarcoma.
A choriocarcinoma and some parasitic nuclei. In 15 to
17 are seen parasites whilst still inside the host-nucleus to
FIG. 55. VARIOUS STRUCTURES IN THE CHORIOCARCINOMA. 1, Free
chromidial parasite ; 2, intracytoplasmic parasite ; 3, 4, free parasites
with peripheral chromatin granules ; 5, free chromidial parasite with
a nucleiform chromatin-net ; 6, free parasite with chromatin granules ;
7, ibid., with temporary nucleus-like bodies ; 8, nucleated filaments
and a spiral attached to an oval body ; 9, several intracytoplasmic
bodies, some assuming spiral form ; 10, plasson masses splitting into
spirals ; 11, Leydenia-form free in blood-vessel ; 12, two parasitic
masses in a blood-vessel breaking up into stellate amoebulae ; 13, intra-
nuclear parasite with knobbed processes ; 14, similar parasite escaping
into cytoplasm ; 15, intranuclear parasite with granular extensions ;
16, ibid., with extensions in the form of stellate amoebulae ; 17 ibid. ;
18, end-view of mitosis in a parasite ; 19, ibid., profile ; 20, intra-
nuclear parasite in mitosis with chromidial granules outside the
nuclear figure. X 800. From Part IV.
190 PKOTISTS AND DISEASE
be passing from the pycno- to the chasmatoplasson state,
resulting (in 16 and 17) in the production of stellate amoe-
bulae. In 21 is an early anaphase in an intranuclear parasite
with chromidial particles distributed in the plasm : 20, a
similar parasite at metaphase.
The two views of mitosis 18 and 19 show chromosmes
quite unlike those of any human cell and quite like those of
Plasmodiophoraceae and Mycetozoa.
Expansion into and formation of stellate subdivisions
and mitotic subdivision are here alternative processes.
Fig. 55, 21 shows a mixture of the two. A few instances of
subdivision of intranuclear parasites I observed also in the
mammary sarcoma described above.
The sections of the choriocarcinoma which Professor
Primrose kindly gave me are perfectly stained with iron-
haematoxylin, a process which shows certain nuclear features
better than does acid haematoxylin.
Conclusions and Comparisons. If the sarcoma of the
breast (Figs. 53 and 54) of which a fuller account is given in
Part II, were the only tumour known, and the cytology of
granulation-tissue were also known, we should be justified
in concluding that the tumour was caused by a parasite which
first invades the nuclei of connective-tissue cells, escapes
thence into the cytoplasm of the host-cell and thence again
into the intercellular spaces. The parasite subdivides either
with or without the formation of chromatin into amoebulae
which tend to assume a stellate form. When chromatin
SMALLPOX, SYPHILIS, CANCER, ETC. 191
appears in the parasite it may have the form of nuclei with
achromatic linin fibres.
Those who from year to year have numbers of malignant
tumours to examine will find some in which the parasitic
features are as plain as in this mammary sarcoma. In another
growth of the same kind I found the intracellular stages easy
to be seen, but other stages were hard to see owing to the
parasites being in a more labile state. Fresh teasings are
required in such cases. In slow-growing cancers parasites
are naturally fewer, but with patience they can be found
even in rodent ulcer, one of the slowest and least malignant
forms of cancer.
Synchytrium and cancer. On comparing Fig. 23 with
Fig. 54 it is seen how closely the larger intranuclear parasites
in this sarcoma resemble the nucleolus of the thistle-
Synchytrium, presenting club-shaped or more slender knobbed
processes from which chromatic substance is differentiated ;
a conversion of pycno-plasson into chasmatoplasson or into
chromidium. The sarcoma parasites in some cases fuse
into plasmodia ; the latter feature is not so prominent as it
is in cysts caused by Olpidiiforma, Fig. 46.
In Fig. 24 ; a, the nucleolus of a Synchytrium is seen to
have become amoeboid ; now had such a parasite been
reduced to the condition of its nucleolus as is the case in
plassomyxines, and had met another in a similar state the
two would doubtless have fused into a plasmodium.
In the choriocarcinoma, Fig. 55 ; 15 to 17 the intra-
192 PROTISTS AND DISEASE
nuclear parasites are almost identical with stages of the
nucleolus of the thistle-Synchytrium, Fig. 23 ; d and e.
In its earlier phases the sarcoma-parasite follows the
course of Plassomyxa contagiosa, differing from the latter as
also do Cytoryctes variolae and C. luis in that the stages
ending in subdivision occur in the host-tissues.
This instance of a typical sarcoma proves Cohnheim to
have erred in narrowing the term tumour to exclude infective
granulomatous growths.
Epithelial cancer. To illustrate this variety of malignant
tumour I will dwell chiefly on that which arises in stratified
squamous epithelium because, as if from synchytrian inheri-
tance, in this habitat the parasites assume their later stages
in greater completeness than in less coherent epithelia ; but
in all spontaneous cancers the pathogenesis is practically
the same. With regard to the original site of the parasites
in this and other spontaneous cancers it is intranuclear like
that of the parasites in the mammary sarcoma described
above.
Intranuclear parasites as seen in a section of a breast-
cancer are shown in Fig. 56.
The first cancer in which I recognised parasites akin to
Sporozoa was a growth arising in that part of the nasal
septum which is covered by skin : it had been removed by
Scanes Spicer from a man aged 82. The moisture of the
cavity in which the tumour grew had allowed parasites,
which are usually distorted and disguised in the cell-nests
SMALLPOX, SYPHILIS, CANCER, ETC. 193
in average specimens of this kind of cancer, to assume their
natural shape and to exhibit the process of sporange-
formation and subdivision.
The subjoined quotation from Part III (1912) in addition
to the description beneath Fig. 57 indicate the more important
points.
FIG. 56. INTRANUCLEAR, INTRACYTOPLASMIC, AND FREE PARASITES IN
CANCER or THE BREAST. Drawing eye-piece, x 800 diams. From
Part IV.
" I would draw attention to two points, however. First,
the occurrence of coccidia-like forms, Fig. 57, 9-12, in
squamous epithelioma similar to those described by Souda-
ke witch (1892) in cancer of the breast. These forms are
brought into series with those shown in 1 to 8 by connecting
forms, so they are clearly not coccidia. Insistence on such
13
-a/
- 6
d.J.C
FIG. 57. ELEMENTS FROM SQUAMOTJS EPITHELIOMAS. 1, 2, 3, parasites passing
from the pycnoplasson phase by processes akin to mitosis ; 4 and 6, ibid.,
by formation of pseudoleucocytes ; 8, one of latter becoming separated ; 9 to
12, coccidiomorph intracellular parasites ; produced from pycnoplasson by stages
seen in 10 ; 7, a, sporangium with chromatin rods in some subdivisions. From
Part III.
FIG. 58. Two SPORANGIA FROM A SQUAMOUS-CELLED CANCER OF THE SEPTUM NASI
7, A framework contains four parasites ripe for development into sporangia,
such as the one in the same framework which is continuous with its capsule ; the
latter is poorly developed and six leucocytes have penetrated among the spores ;
2, the large sporangium contains granular spores, its well-formed capsule ( = peridium)
is continuous at one point with the rest of the framework, which contains some
highly refracting granules, probably lime. From Part IV.
196 PROTISTS AND DISEASE
and other exclusive forms as the only parasitic protozoa in
cancer has really kept back the recognition of the nature of
the disease."
Instead of the word " protozoa " in the foregoing extract
I should now write " protists."
Sporangium-formation in cancer. Although seen only
occasionally in sections of cancer sporangia are quite un-
mistakable, as shown in Fig. 58.
Such definitely encapsuled structures do not occur in
normal human tissues ; the definite chromatin bars seen in
some of the subdivisions of Fig. 57, 7, show that the process
is not one of degeneration. By study of even some single
sections of this tumour such sporangia were seen to be the
end of a series of phases of which the earliest are intranuclear
bodies in the plasson state.
Alternative modes of reproduction in cancer-parasites.
In very rapidly-growing squamous-celled cancers the para-
sites instead of growing for a time in the plasson state,
divide by mitosis as soon as they escape from the nucleus in
the same way as some of those of the mammary sarcoma
described above, and those of the last stage of the infective
sarcoma of dogs described in Part II.
To take one instance : At the Hampstead General
Hospital a cancerous gland was removed from the left
parotid region of a woman aged seventy-one years. The
patient had been operated on four months earlier for a
growth below the left eyelid, and the pathologist had
SMALLPOX, SYPHILIS, CANCER, ETC. 197
reported that the growth was a typical squamous-celled
cancer.
After removal of the gland, which was of the size of a
small walnut, an incision was made into it, revealing a
central cavity lined by a layer of yellowish material about
2 mm. in depth, easily separable from the firmer tissue
beneath. Sections were made by Dr. Wyatt Wingrave,
pathologist, who stained them with pyronin and methyl
green. 1
The section I have is beautifully stained and well fixed.
It shows that a layer of healthy parotid was cut away with
the tumour, and that the latter is a typical squamous-celled
cancer. There are in the younger epithelial cells what
appear to be unusually prominent nucleoli. On close
inspection some of the latter are seen to have escaped from
the nuclei and then to have expanded suddenly, i.e. before
getting clear of the host-nucleus, and to have become them-
selves nucleated, and with their nuclei to be dividing by
direct cell-division.
The process in this squamous-celled cancer was the same
as that of the free parasites of cancer of the uterus described
in Part III.
Spirochaetes in cancer. Spiral forms of parasites con-
sisting almost entirely of chromatin I described in Part II
1 The following are the details of the method : 3 parts aqueous solution of pyronin ;
1 part saturated solution of methyl green. Stain five minutes or longer, transfer to
fresh solution of resorcinol (3 grains to watch-glass) for one minute, then to solution
of resorcinol in absolute alcohol (0*6 grain to watch-glass) till sufficiently decolorised ;
then three changes of absolute alcohol, and two of xylene. Mount in dammar-xylene.
198 PROTISTS AND DISEASE
in the mammary sarcoma ; and Fig. 55, 8 to 10 (chorio-
carcinoma), shows other similar forms. Such forms are I
think, alternative to the amoebula. Gaylord once met
with a definite spirochaete in mouse-cancer. I have no
doubt that, if regularly looked for, such instances would
be multiplied, but until it is generally recognised that the
spirochaete of syphilis is but one of a series of phases of
Cytoryctes luis, I do not think much can be gained by regular
search for spirochaetes in cancer. The infective sarcoma of
dogs in which Mettam found spirochaetes might be a useful
condition to compare with syphilis.
Cultures of cancer-parasites. We must imitate nature's
ways if we are to succeed in cultivating certain organisms.
In the natural process the parasites of molluscum are
extruded and fall from the host : we should expect them to
develope in water, and so it is found to be by experiment.
Plassomyxa contagiosa produces broods of new individuals
outside their chief host, exogenously as it is termed.
In cancer the parasites breed endogenously passing through
repeated cycles which end only with the death of the host.
To imitate nature's way in cancer we must cultivate the
parasites in the tissues or fluids of the host and at the tempe-
rature of the host. Gaylord has used this method with success.
We have seen, Chapter VI, that the commonest mode of
subdivision of Plassomyxa contagiosa is by the formation of
oil-like spheres, the protoplasm of which may circulate for
hours or days.
SMALLPOX, SYPHILIS, CANCER, ETC. 199
From a colloid cancer of the peritoneum Gaylord obtained
crowds of such greenish bodies, which he found not to
consist of fat, and he placed them in tubes in an incubator
in the peritoneal fluid. The changes he observed in these
bodies were : 1, increase in size with change from a homo-
geneous to a granular state with loss of the green colour ;
2, Brownian movement of their granules ; 3, formation of
pseudopodia ; 4, the formation of nuclei in the previously
akaryote bodies. It may be noted that 3 corresponds with
the body, Fig. 55, 11, in a section of a choriocarcinoma, and
4 with a similar appearance of nuclei in Plassomyxa cont.
Fig. 31, 6 and 7.
Gaylord injected some of his cultures into the peritoneum
of dogs and guinea-pigs, and relates that he obtained in
sSome cases cancerous growths, in others peritonitis.
Besides the endogenous cycles in cancer the parasites
would appear also to have an exogenous period in some
instances. Such a condition is most likely to be found in
epidermal cancer. With material from the secondary growth
over the parotid mentioned above I made a water-culture
which remained free from bacteria for several days. Water-
mounted fragments showed a surprising variety of encap-
suled and other protist-like forms, which were entirely
concealed in sections. On the 9th day what looked like
small zoospores developed from clusters of round homo-
geneous globules : I hope to repeat this observation.
Plassomyxa forma-maligna. W T hen we examine a section
200 PROTISTS AND DISEASE
of a fully-developed molluscum-tumour, such as that shown
in Part IV, Plate III, after allowing for the loose parasites
that have been detached in mounting the section, we can
compute the proportion of parasites to host-tissues as rather
more than 1 to 2.
In the section of the mammary sarcoma, Part III, Fig. 32,
we see that the proportion of parasites to host-tissue is
again something near 1 to 2 ; and again in the squamous-
celled cancer of the nasal septum as illustrated in Plates IV
and V, Part III, we see again about the same ratio holds
good. As I stated in 1892 about one third of the weight of
rapidly-growing cancers is accounted for by the visible
parasites present in them.
Can we name the parasite of cancer ? We must first
consider the transformation of late syphilis into cancer and
reflect that in some cases we shall probably be naming
Cytoryctes luis over again.
By their particular harmony with the host-cells and
tissues the parasites produce the anatomical varieties of
malignant tumours. Some of these tumours have features
so pronounced that a brief inspection by the microscope
enables the pathological diagnosis to be made ; in others,
again, only after careful study can a decision be reached ;
and, in not a few cases, it is impossible by the microscope
alone to distinguish between cancerous and syphilitic or
other inflammatory processes.
In general, however, we can recognise a special setting
SMALLPOX, SYPHILIS, CANCER, ETC. 201
of the parasites in cancer, and without prejudice to future
specific recognitions we may name the parasites : Plasso-
myxa forma-maligna.
Imitation- cancer. If I wished to make an imitation of
cancer, I would devise a set of the thinnest knives about
1 mm. long mounted in bunches at the ends of fine steel
stems. Pushing with aseptic precautions a bunch just
through the skin the knives should be left in place till the
epidermal cells had grown beyond their points, which then,
increased in number, should again in various directions be
pushed deeper. This process repeated for a long time would
reach lymph-glands, and a series of ropes of epidermal cells
would stretch from skin to glands.
Those, who from day to day are exposed unprotected (as
in screen-work) to X-rays, repeat in a way the above
imaginary experiment ; the connective-tissue-damaging rays
taking the place of knives. As is shown in Part IV X-rays
epithelioma contains no parasites : it is an imitation-cancer.
The best imitation-cancer I know of was obtained by
Lambert Lack, who injected an emulsion of its ovary into
a rabbit's peritoneum. Cancer-like growth followed in
peritoneum and glands. Mr. Lack kindly gave me two
sections. Careful examination showed there were no para-
sites ; it is an imitation-cancer, a very exceptional case of
cell-transplantation. It might easily have been a real
cancer, if the rabbit had had in it seasoned plassomyxes,
wilich found in the emulsified cells suitable hosts.
202 PROTISTS AND DISEASE
In some minds will arise the question " What about
khangri-pots and tar ? " Cancers induced by such means
should be examined carefully. If they are of the same
nature as common spontaneous cancer, they will be found
to contain plassomyxes ; and the only conclusion that can
be drawn will be that these two agents are favourable to
the establishment of that particular relationship between
tissue cells and parasites that constitutes common human
cancer.
And Cohnheim's embryonic rests ? Where such rests
really exist their cells may function in producing for us
internal secretions ; when they are the seat of cancer it
means that certain plassomyxes have found them to be
suitable hosts.
Metastasis. It is usually assumed that the only way
by which a secondary malignant tumour can arise is by
metastasis, that is by the detachment of a portion of the
original tumour and development of the transplant in
another part of the patient's body. In sarcomas as, for
example, Fig. 46 ; 12, we see many parasites free in small
veins, therefore in such tumours secondary growths can
arise simply by the parasites finding elsewhere host-cells
similar to those of the original tumour.
The mammary sarcoma referred to above is a granuloma,
and examination showed that the secondary growths arose
in all probability by migration of parasites. That meta-
stasis may occur in sarcoma is also seen in examining in the
SMALLPOX, SYPHILIS, CANCER, ETC. 203
same tumour the multitude of large amoeboid parasites
lying in intercellular spaces could easily detach portions of
the growth and, if the host-cells of the latter had been
rapidly dividing, metastases would have occurred.
Where a melanotic sarcoma of the choroid of the eye is
accompanied by secondary growths in the liver, we assume
that metastasis has occurred, and so it may be, but not
necessarily ; for the parasites may be capable of causing
granular pigmentary change in previously unpigmented
connective-tissue or endothelial cells.
In epithelial cancer, as for instance where growths
secondary to a cancer of the thyroid are present in the skull,
metastasis must have occurred and it is easily explained by
the movements of the parasites detaching portions of the
tumour into lymphatics or veins and so into the blood-
stream to find lodgment in parts best suited to growth of
the transplants.
Conclusions. Before one ventures to formulate con-
clusions the real objective position should be clearly defined.
In parasitism by common fungi we saw in Chapter II how
vast numbers of the parasites perish. The same feature
presents itself in syphilitic gumma and in sarcoma. This
fact was emphasised in 1901 by Gaylord : " All the organs,
including the blood, taken from all regions of all cases dying
of cancer, including sarcoma and epithelioma, contain large
numbers of the organisms." Fresh teasings reveal the
presence of parasites in forms that are concealed by routine
204 PROTISTS AND DISEASE
histological methods. Besides visible forms there are doubt-
less many in the microhenad phase. Secondary growths
are few compared with the number of parasites distributed
through the host body.
Cancer being so common we all at some time or another
probably have in us potential cancer-parasites. How do
they get into us ? It has been shown above and in Part IV
that in old-standing syphilis cancer seems to arise in a
peculiar relationship of Cytoryctes luis to the host- cells. A
similar relationship between the parasites of measles and
other exanthems may possibly produce cancer : these are
problems for future investigation. The frequent presence
of Karyoryctes in water-protozoa suggests the question
whether that or similar plassomyxines may not in some
cases become Plassomyxa forma-maligna in man or other
mammal.
Adenoma of the breast, &c. -The cells which line the
younger cysts of this common fibre-cystic tumour are
swollen, and contain spherical inclusions of colloid-like
(pycnoplasson) aspect, the largest on escaping by breaking-
up of the cell become a mass of fine granules in the lumen.
These and other features point to these bodies being of the
same nature as the plassomyxes described above in smallpox,
syphilis and cancer. In the latter disease as might be
expected the parasites are in a state of more aggressive
vitality than in the simpler adenoma, and until the more
demonstrative features of the parasites in cancer are accepted
SMALLPOX, SYPHILIS, CANCER, ETC. 205
I do not think much is to be gained by a detailed account
of foreign structures met with in benign neoplasms, with
the exception of molluscum contagiosum, where they can
easily be cultivated. But the appearances in breast adenoma
bear one important message, namely that plassomyxes
are capable of indefinitely prolonged life and reproduction
in the plasson state.
Cell-inclusions are abundant in some adenomas of the
thyroid gland, and in the common tumour of the prostate
certain features suggest that plassomyxes exist in intimate
association with connective-tissue cells.
Hydrophobia. The incubation of this disease is of
very variable duration, between 15 and 60 days as a rule
but it may be even longer.
Negri first described corpuscles in cells of the central
nervous system of animals killed whilst suffering from
hydrophobia. He regarded the bodies as parasites and
named the species Neuroryctes lyssae.
Negri-bodies are visible in fresh unstained preparations.
In dogs that have been killed on account of this disease
(street rabies) the bodies may measure 18 p, or more ; in
rabbits that have been inoculated with virus that having
been passed through a series of rabbits has acquired a
definite virulence (fixed virus), the bodies are small, ^p.
or less.
By means of Negri' s bodies a diagnosis can be made in
a few minutes from smears of a suspected animal's brain.
206 PROTISTS AND DISEASE
For this purpose Williams and Lowden recommend smears
made by placing small pieces cut by scissors from the Cornu
Ammonis, the Rolandic area, and the cerebellum. A
fragment is laid on a slide leaving room for a label, then a
coverslip is laid on the fragment and by even pressure made
to move to the opposite end of the slide.
The smears are dried in air and stained either by Giemsa's
method after fixation in methyl alcohol, or by Mallory's
eosin-methylene blue stain after Zenker's fluid. Not only
Negri-bodies but also the swellings on the nerve-fibres, and
the collections of lymphoid cells are well shown by this
method, which the authors prefer to the section method.
Only in animals infected by fixed virus do sections give
better results than smears. The bodies were found on the
4th day in fixed virus cases, and on the 7th day in street
virus cases.
The elements a, and 6, in Fig. 59 I drew from a section
kindly given me by Professor J. H. Ashworth, who had it
from the Pasteur Institute, Kasauli, India. It appears to
be stained with H. and E. We may note in the cell b that
the nuclear membrane is broken at the upper end and
granules appear to have been passing from nucleus to
cytoplasm ; below, again, a pyramidal process joins the
nucleolus to the nuclear membrane, as if in preparation for
a subsequent discharge of granules.
Now it would be a reasonable suggestion that the Negri-
bodies resulted from a fusion of such granules. This would
SMALLPOX, SYPHILIS, CANCER, ETC. 207
hardly account for chromidial forms, c, and not at all for
well-formed nuclei such as that at d being present in some
of these bodies : such nuclei recall Olpidiiforma, Fig. 46, 5,
and the temporary nuclei in Plassomyxa contay., Fig. 31, 6
and 7 ; in syphilis, Fig. 52, x and y ; in cancer, Fig. 55,
5, &c.
FIG. 59. NEGRI'S BODIES IN HYDROPHOBIA, a and b, two adjacent
cells in the Cornu Ammonis of a dog ; a contains a vacuolated Neuro-
ryctes, another is in the brain substance near ; 6, contains three small
parasites below the nucleus ; c, brain-cell of a dog from a smear and
five large parasites ; d, a large parasite with a nucleus, a and 6,
X 1000 ; c, after Williams and Lowden ; d, from Calkins after Negri.
Pasteur. One cannot leave the subject of hydrophobia
without thinking of one name, that of Louis Pasteur, who
began his work on hydrophobia in 1880 and treated his
first human patient with success in 1885. It may be wholesome
for us to reflect that perhaps the greatest name in the history
of medicine is not the name of a medical man.
Pasteur's antirabic vaccine is the only true vaccine
208 PROTISTS AND DISEASE
besides the vaccine of Edward Jenner that is used in human
medicine. The first injection is an emulsion of infected
rabbit's spinal cord desiccated during 14 days ; and, in
increasing strength, doses of fixed virus are given for 15 days,
the last being of 3-day cord.
Nucleoli. "The nature of true nucleoli is still imper-
fectly known " wrote Wilson in 1904. It may well be that
study of the large nucleoli of brain cells in hydrophobia will
afford some information. The granules escaping from the
nucleus at b in Fig. 66 may represent the immediate means
of defence possessed by the brain-cell. Wilson mentions
that the subcutaneous gland- cells of Pisciola contain but a
single nucleolus, but during growth of the cell the nucleolus
fragments into several hundreds of nucleoli, which then
appear to migrate into the cytoplasm, leaving but a single
one to grow and repeat the process. Writing of chromidia
in Part IV I suggested that the specific products of the
highly specialised cells of metazoa, for example the secretions
of gland-cells, may be chromidial in origin. It seems as
though in nuclei that have permanent chromosomes there
may be a division of labour, reproduction devolving chiefly
on these whilst the nucleolus, in what we call resting nuclei,
furnishes secretions of different kinds for diverse purposes.
Vaccines and pro- vaccines. As stated above there are
in human medicine only two vaccines, the Jennerian and the
Pasteurian. In general a vaccine is definable as an attenuated
culture of a pathogenic organism ; i.e. it contains living
SMALLPOX, SYPHILIS, CANCER, ETC. 209
parasites. By appropriate treatment when they are culti-
vable on artificial media such vaccines can be ' fixed ' at any
given grade of virulence. Although it is not cultivable
artificially the virus of hydrophobia can be fixed as explained
above.
In misleading language the term c vaccine ' has been
applied to an important class of preparations of dead
leria. They should be called ' pro- vaccines.' In the
J x^af jtha typhoid group of
d its originators
>uld be found to
ice to humanity
. Unfortunately
* serum or pro-
ice the course of
A community un-
vaccinated ana iievoj. ^~ r js or scarlet fever
suffers terribly whenever smallpox or other exanthematous
fever appears in it : the healthiest, noblest specimens of
manhood and womanhood die, we having no remedy.
Ought we to seek attenuating hosts for the parasites of
measles, scarlet fever, &c. as we have the calf to attenuate
the virus of smallpox ? Our knowledge of syphilis gives us
pause. We know that immunity to syphilis means having
the disease : having the specific parasites living in the
tissues of the immune person.
14
208 PROTISTS AND DISEASE
besides the vaccine of Edward Jenner that is used in human
medicine. The first injection is an emulsion of infected
rabbit's spinal cord desiccated during 14 days ; and, in
increasing strength, doses of fixed virus are given for 15 days,
the last being of 3-day cord.
Nucleoli. " The nature of true nucleoli is still imper-
fectly known " wrote Wilson in 1904. It may well be that
study oJ
In reading the passage beginning " Specific remedies " it
nucleus should be borne in mind that nearly everyone contracts measles
of defer and scarlet fever, just as without vaccination we should all have
, , small pox. If true vaccines were found I think they should
be tried in measles and scarlet fever; but at the same time
single m sterilising remedies should be sought for.
f ragmem TO face P . 202
appear t
one to g
in Part v i isuggesteu tiiat tne specinc products oi the
highly specialised cells of metazoa, for example the secretions
of gland-cells, may be chromidial in origin. It seems as
though in nuclei that have permanent chromosomes there
may be a division of labour, reproduction devolving chiefly
on these whilst the nucleolus, in what we call resting nuclei,
furnishes secretions of different kinds for diverse purposes.
Vaccines and pro-vaccines. As stated above there are
in human medicine only two vaccines, the Jennerian and the
Pasteurian. In general a vaccine is definable as an attenuated
culture of a pathogenic organism ; i.e. it contains living
SMALLPOX, SYPHILIS, CANCER, ETC. 209
parasites. By appropriate treatment when they are culti-
vable on artificial media such vaccines can be ' fixed ' at any
given grade of virulence. Although it is not cultivable
artificially the virus of hydrophobia can be fixed as explained
above.
In misleading language the term ' vaccine ' has been
applied to an important class of preparations of dead
bacteria. They should be called ' pro- vaccines.' In the
late war the immunising pro- vaccine of the typhoid group of
bacteria appears to have been successful and its originators
deserve our gratitude. If a pro-vaccine could be found to
replace the vaccine efficiently, such a service to humanity
would be greater even than that of Jenner. Unfortunately
no sterile substance, whether immunising serum or pro-
vaccine, has as yet been found to influence the course of
any of the common exanthemata.
Specific remedies for specific fevers ? A community un-
vaccinated and never exposed to measles or scarlet fever
suffers terribly whenever smallpox or other exanthematous
fever appears in it : the healthiest, noblest specimens of
manhood and womanhood die, we having no remedy.
Ought we to seek attenuating hosts for the parasites of
measles, scarlet fever, &c. as we have the calf to attenuate
the virus of smallpox ? Our knowledge of syphilis gives us
pause. We know that immunity to syphilis means having
the disease : having the specific parasites living in the
tissues of the immune person.
14
210 PROTISTS AND DISEASE
We cannot advise vaccination against syphilis, the
parasite of which may lurk in the tissues for a number of
decades without evidence of their presence, and then produce
some obvious late lesion. Have the common exanthems
sequels corresponding to those of the fever of syphilis ?
Looking through the index of any book on diseases we
note in addition to cancer and exanthems others of unknown
causation. May not some be caused by the parasites of
long-past fevers the causal germs of which still live in us ?
We have specific treatment for syphilis. If we had safe
and sure specific remedies for the common specific fevers,
we might by their use prevent other diseases including
possibly some cases of cancer.
Virchow. In all its epochs pathology has been befogged
by more or less mock-knowledge : we have had our own
nebula, " parasyphilis," which a little real knowledge has
dispelled. Virchow cleared away a great accumulation of
such pseudopathology. He found Schwann's merit to consist
in the recognition of the cell as the origin of all tissues and
physiological properties. His own instruction reads : " I
formulate the doctrine of pathological generation, of neoplasia
in the sense of cellular-pathology simply : omnis cellula a
celluld."
Tumours in present-day pathology. Having been no
more than an amateur in pathology for 26 years past some
important advance may have escaped my notice ; at any
rate I can only think of one accepted change that has been
SMALLPOX, SYPHILIS, CANCER, ETC. 211
made in the last 30 years respecting the pathology of cancer :
what used to be called an alveolar sarcoma is now called a
perithelioma. The insistance is on histogenesis ; a slight
movement on a road well made by Virchow. And what a
good road it has been and will continue to be ; helping us
to decide points in diagnosis and prognosis, and affording
reliable indications as to treatment ; helping us to trace the
primary seat of growth when the tumour that is the first to
show itself clinically is found to be composed of tissue foreign
to that in which it occurs ! Certain types of cell-forms and
of structure in tumours we know to be associated with
corresponding degrees of malignancy.
Beyond Virchow' s is another road, at present a mere
track in places. The old road must be patiently traversed
before the new one can be reached. Unless this new road
is followed patiently and thoughtfully, and all the menacing
objects it brings into view are scrutinised critically and
tested by experiments planned on natural lines, the causes
of the diseases dealt with in this book and of many others
must remain unappreciated.
CHAPTER XI
CHROMIDIA AND NUCLEI OF A PROTOZOON
AMONG the vegetable protists noticed above the chytridian
Polyphagus euglenae ; olpidians, such as Rozella septigena ;
and synchytrian? present features similar to some found in
rhizopods and sporozoa.
Facts stated above indicate that Plassomyxineae are
closely related to Synchytriaceae, and hence they too must
be considered as belonging to the vegetable protists. Myce-
tozoa have so many rhizopod features that their animal
predominate slightly over their vegetable characteristics.
In the present Chapter is given a brief account of chromidial
and nuclear features of a definitely animal protist, one of
the shelled amoebas. The shelled amoebas have no patho-
genic members. Matters relating to amoebas parasitic in
man have been defined by Dobell (1919) ; Entamoeba
histolytica, the cause of amoebic dysentery has no connection
with any free-living organism. It was discovered by Loesch
in 1875, and named by him Amoeba coli, under which name
it is described and illustrated in Part I. It has not been
cultivated on artificial media. Extranuclear chromatic
212
CHROMIDIA AND NUCLEI OF A PROTOZOON 213
structures occur in it and were called chromidia by Schaudinn,
but Dobell states that they have nothing in common with
true chromidia such as occur in Arcella.
It has been recorded in Part IV how complicated the
life-cycle of a common amoeba is. Calkins has followed the
nuclear process in Amoeba proteus. In the case of organisms
of indefinite form it is difficult for the student to retain a
mental picture of a complicated series of nuclear and chro-
midial processes, and of cell- divisions. This is easier in the
case of the shelled amoebae. Of one of these, Arcella vulgaris,
the life-history has been worked out with some degree of
completeness, 1 so we may take this organism as an example.
Arcella (Ehrenberg) is a common and widely distributed
genus. Arcella vulgaris occurs chiefly in bogs and other
still waters. Seen in surface view it has the appearance
shown in Fig. 60 : 1. Its flattened dome-shaped brown-
coloured shell is finely tessellated, and measures from 80/x, to
140//, across. In profile view the shell is seen to have a
diaphragm with a central perforation, the pylome, less than
one-third the width of the shell. A section of the shell
shows it to consist of an inner continuous chitinous layer,
slightly exaggerated in thickness, 2, b ; the close-set cuboidal
elements of the outer layer are cemented together by the
same substance as that which forms the inner layer. From
1 In order to compile the following sketch I consulted various authors : Delage and
Herouard, 1896; E. A. Minchin, 1901 ; G. N. Calkins, F. Doflein, and S. J. Hickson,
1909. The chromidial phases were worked out by R. Hertwig, the structure of the
shell by Awerinzew, the gametes by Elpetiewsky.
214 . PROTISTS AND DISEASE
the pylome three or four finger-like pseudopodia project.
FIG. 60. ARCELLA VULGARIS. 1, Surface ; 2, Profile ; 6, Section of part
of shell ; 3, Binary division ; 4, (seen on the flat) Resting state,
trophonuclei, N ; and chromidium, Chr. ; 5, Formation of new nuclei
from chromidium. From various sources.
In the vegetative phase, which is assumed in summer when
food abounds, the animal has two nuclei, each with a large
CHROMIDIA AND NUCLEI OF A PROTOZOON 215
nucleolus and a nuclear membrane. A circle of gas vacuoles
is often seen round the pylome, or they may be united into
one eccentric vacuole. One or more contractile vacuoles
are also usually present. The animal does not completely
fill its shell with which the ectoplasm is in contact only at
a number of points.
In the ordinary binary division the two nuclei divide
simultaneously by a simple form of mitosis, 3, after part of
the animal's body has been protruded through the pylome.
The two new nuclei with other cell-elements pass into the
protruded part which secretes a new shell, and soon separates
from the parent organism.
When an Arcella is viewed from above the outline of the
pylome shows as an inner doubly-contoured ring, and
another and very important feature is seen the chromidium,
4 and 5, Chr. In the vegetative state of the animal the
chromidium consists of a circle of rather coarse granules,
which pass to the outer side of the nuclei with a little space
between. In winter the chromidium plays its part in
reproduction in various ways. First, the fine granules of
chromatin, hardly noticed between the other granules of
the resting chromidium, become larger and run together to
form new nuclei. The subsequent fate of these is indicated
in Fig. 61, 5 to 11.
In certain conditions Arcella encysts, forming a dense
cyst-wall which blocks the pylome. Before encystment
occurs food-remains (diatom shells) are extruded into the
216
PROTISTS AND DISEASE
FIG. 61. DIAGRAM SHOWING THE CHIEF LIFE-PROCESSES OF ARCELLA
VULGARIS. From various sources.
CHROMIDIA AND NUCLEI OF A PROTOZOON 217
empty corners of the shell, Fig. 61 : 2. At other times the
animal leaves its shell, 3. The chromidial reproductive
stages are of two kinds, non-sexual and sexual ; and the
sexual processes are again of two kinds, nuclear (karyogamy)
and chromidial (chromidiogamy). The asexual chromidial
reproduction is shown in Fig. 61 : 5, 6, and 7 ; really three
degrees of the same process. New nuclei formed from the
chromidium, together with the adjacent zone of cytoplasm,
become buds, which may be formed slowly, 5, or more
rapidly, 6 9 or very rapidly after the animal has left the shell all
but the two trophonuclei with a little plasm, 7. Karyogamy
is depicted in 8 and 9. Many chromidial nuclei, rather
larger in the female than in the male gamont, are formed,
and they become the nuclei of the male and female sex-cells
(gametes), which coalesce.
Chromidiogamy is shown in 10 and 11. Two Arcellae,
after adhering by their pseudopodia, come pylome to
pylome, and they fuse together, nearly the whole of the
substance of one animal passing into the shell of the other
and, after mixing, returning again. The animals then
separate. The trophonuclei break up and new nuclei are
formed from the chromidium to become the nuclei of buds.
In whatever way buds are formed they all pass through the
same phases before they assume the Arcella-form. These
phases are shown in 12, 13, and 14 ; 13 is called the Nudearia
stage.
Still another vital process common to many protozoa,
218 PROTISTS AND DISEASE
and called either plastogamy or plasmogamy, is illustrated
in 15. Several Arcellae join pseudopodia, protoplasmic
currents are interchanged ; the animals then separate.
The above brief survey of the salient life-processes in
one of the Rhizopoda Lobosa suffices to show that the
chromldial phases are essential, and that the sexual repro-
duction is confined to them. If the summer phases of the
organism alone had been studied the most important part
of its life-history would be unknown.
If we examine an Arcella in the stage shown in Fig. 60 :
5, separate granules stained like chromatin are recognisable
in the cytoplasm. The term " chromidiosomes " has been
applied to such granules.
The cell-theory adjusted to facts. As depicted by different
observers Arcella vulgaris passes through two non-nucleated
phases ; namely, that immediately preceding the condition
shown in Fig. 61, 8 and 9, and that shown at 10. These
two may be considered as modifications of the same phase.
The distributed nuclear matter seen in some Ciliata
such as Chaenia teres, and in Cyanophyceae, such as Chroo-
coccus turgidus, may, I think, be regarded as true nuclei.
The Chroococcaceae were regarded as non-nucleated by
Haeckel. It is different with the chromidial phases of
organisms such as Arcella and Sorosphaera (Chapter VII) :
in these new nuclei arise, nqt by simple transverse division,
but by confluence of chromidial granules.
We may infer from the unqualified acceptance of Flem.
CHROMIDIA AND NUCLEI OF A PROTOZOON 219
ming's " omnis nucleus a nucleo " in even the most recent
works on cytology, that the well-known fact just stated has
not been duly digested in biology. One effect of this is
seen in the otherwise unaccountable grouping of Karyoryctes
cytoryctoides with Nucleophaga amoebae as related in
Chapter X.
The confusion just indicated is to be explained only
by want of recognition in biology of the plasson state of
living matter as seen in the zygotic sporange of Synchytrium,
Fig. 23, d and e, and in pathogenic organisms such as are
shown in Fig. 29, and Fig. 54, 1 to 4, &c.
That Borrel did not realise that the appearance of new
nuclei in Cytoryctes variolae, Fig. 48, 2, proves this body to
be a parasite can only be accounted for by the inadequacy
of the cell-theory as at present accepted.
The streaming protoplasm of Plassomyxa contagiosa has
no recognisable structure, but new nuclei are occasionally
formed in molluscum bodies, as they are in the parasites of
syphilis and of cancer.
All these instances are exceptions to the " omnis nucleus
a nucleo," and herein we may see the explanation of the fact
that smallpox and other fevers, cancer and other tumours
are academic enigmas to-day.
If the cell-theory is adjusted to amply proven facts it
must read : New nuclei arise not only by division of pre-
existing nuclei, but also by free nucleus-formation from
chromidia or from plasson.
ABBREVIATIONS, &c.
M.G. and S. stands for my " Morbid Growths and Sporozoa " ; condensed
from " Cancer, Sarcoma, and other Morbid Growths Considered in
Relation to the Sporozoa," published in 1893.
Parts I, II, III, and IV, stand for the parts of my " Protozoa and Disease,"
published in 1903, 1908, 1912, and 1915, respectively.
H. and E. means haematoxylin and eosin ; i.e. acid haematoxylin made
according to Ehrlich's formula, and Gruebler's water-soluble
eosin ; the stains being used in the ordinary way.
E.-B.-H. means Ehrlich-Biondi-Heidenhain stain.
Ehrlich's acid haematoxylin : haematoxylin 2 gm. dissolved in alcohol
abs. 100 c.c. ; add water dist. 100 c.c. ; and acetic acid, glac. 10 c.c. ; and
alum, to saturation.
The stain must " ripen " by being kept in the light and having the
stopper of the bottle removed to admit air from time to time. When ripe
it has a dark red colour, the haematoxylin having been oxidised to haema-
tein. The mixture can be kept for years without deterioration. It answers
well for staining in bulk. For staining sections it is diluted with distilled
water, sections become a brown colour, the blue colour being developed in
tap-water.
For counterstain, water-soluble eosin (Griibler's) kept in alcoholic
solution is mixed with water, a few drops to a watch-glass.
Ehrlich-Biondi-Haidenhain triple stain. Saturated aqueous solutions
of orange (100 c.c.), acid fuchsin (20 c.c.), methyl green (50 c.c.) are mixed
in that order with constant stirring. Dehydrate rapidly with alcohol,
clear in xylol and mount in xylol-balsam. This stain is brilliant but fades
so rapidly that I do not now have it used when a permanent preparation
is required.
220
BIBLIOGRAPHY 221
Foa's solution : 1, solution of mercuric chloride in 0*75 saline solution
made by boiling excess of the salt and allowing the solution to cool ;
2, 5 % a solution of bichromate of Potassium. Small portions of tissue
are placed in a freshly made mixture of equal parts of 1 and 2 and after
12 hours are transferred to running water, then to 75 % alcohol and then
to graduated alcohols to which tincture of iodine is added to remove the
mercuric salt from the tissue ; finally to absolute alcohol.
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15
INDEX
(Numbers in heavy type refer to pages with illustrations.)
Acantlwcystis aculeata, 4
Acrasieae, 155, 156, 157
Acrasis, 158
Adenoma, of breast, 204
algae, 22, 24
Ancylistes, 55
Aphragmium, 35
Arcella, 213
Arcella vulgaris, 213, 214, 216
Arcyria incarnata, nuclei of sporangia, 144
bird's-eye bodies in syphilis, 94, 96
bird's-eye bodies of cancer, 92, 93
bird's-eye nuclei, 91, 93, 96
bird-pox, 119
Biologic varieties of fungi, 33
canaliculi, 9
cancer, 183
cancer-bodies, 91
cancer, connective-tissue, 183
cancer, epithelial, 192
cancer, imitation, 201
cancer parasites, alternative modes of
reproduction, 196
cancer parasites, chromatin in, 185
cancer parasites, culture of, 198
cancer, parasites of, 184, 186, 188, 193, 195,
196
cancer, sporangia in, 195, 196
cells, culture of, 10
" cells of endogenous origin," 97
cell-theory, 2
cell -theory adjusted to facts, 218
cellulose, 11
Ceratiomyxa fruticulosa, 137, 157
Chaenia teres, 218
Chaetocladium, 50
chasmatoplasson, 90
chitin, 11
Chlamydozoa, 100
Chlorella vulgaris, 51
chondriosomes, 52
choriocarcinoma, 189
chromatin, 12
chromidia, 4, 5
chromidia in a protozoon, 212
chromidiogamy, 277
Chroococcus turgidus, 218
Chytridiineae, 54
Chytridium, 54
Cladochytriacea, 60
Cladochytrium graminis, 60
Cladochytrium iridis, 26, 60
Chlorochytrium lemnae, 27
Cladonia rangiferina, 50
classification, 16
colours of Mycetozoa, 139
Comatrica nigra, 153
conidia, 19
conidia, resting, 19
Copromyxa, 157, 158
cystic ureteritis, 165
Cystococcus humicola, 27
Cystopus candidus, 42, 43
Cystopus, nuclei of, 42
Cytodes, 2
Cytoryctes luis, 178, 1 82
Cytoryctes variolae, 170, 171, 173
Cytoryctes variolae, intranuclear phases of,
172, 173
Dictyostelium, 156, 158
Dictyuchus, 32
Didymium difforme, 134
diplanetism, 32
Entamoeba histolytica, 212
Erysiphe graminis,, 33
Euglena viridis, 56
filter, kinds of, 108
filtrable viruses, 7
227
228
INDEX
foot-and-mouth disease, 7
Fuligo septica, 132, 152
fungi, 30
fungi, parasitic, 49
gemmae, 47
genus, definition of, 20
germ-hypha and zoospores, equivalence
of, 43
gonidia, 10
granules of Mycetozoa, 139
Guarnieri's bodies, 169
Guarnieri's experiment, 168
gummata, 181
Quttulina, 156
haustoria, 50
Hydrodictyon, 26
hydrophobia, 205
Hymendbolus parasiticufi, 148
Karyoryctes, 175, 176
Lamproderma scintillans. 131
Lecanora esculenta, 51
lichens, 50
life, simulation of, 10
Lycogala epidendrum, 137, 152
Masligella vitrea, 3, 5
Medicine and biology, 15
Microhenads, 108
mitochondria, 14, 52
molluscum, avian, 119
molluscum bodies, changes in, on culture,
104, 115, 116
Molluscum contagiosum, 99
molluscum contagiosum, bacteria in cul-
tures, 117
molluscum contagiosum, further cultural
details, 121
molluscum contagiosum, geographical
distribution, 119
molluscum contagiosum, incubation period
of, 114
molluscum contagiosum, water cultures
for, 102
molluscum tumour, 112
Monera, 1
Mucilago spongiosa, 130, 152
Mucor mucedo, 45
Mucor, nuclei of, 47, 49
Mucor racemosus, 47
Mycetosporidium talpa, 129
Mycetozoa, 131
Mycetozoa, affinities of, 159
Mycetozoa, bionomics, 147
Mycetczoa, chromidia in, 145
Mycetozoa, classification of, 163
Mycetozoa, fertilisation in, 143, .145
Mycetozoa, morphological details, 151
Mycetozoa, sporange-formation, 133, 136
Mycetozoa, stages in liie-cycle of, 132, 134
mycetozoari sporangia, 150, 152
Mycetozoon, culture of a, 148
Negri bodies, 207
Neuroryctes lyssae, 205
nomenclature, 20
nuclear processes in Mycetozoa, 141, 142,
144
nuclei, 12
nucleoli, 208
nucleolus, the synchytrian, 83, 88, 89
Nudeophaga amoebae, 174. 175
nucleus, direct division of, 3
nucleus, indirect division of, 3, 4
nucleus, the synchytrian, 79
Olpidiaceae, 56, 61
Olpidii forma cobboldi, 165, 166
Olpidiopsis saprolegniac, 64, 66
Olpidium brassicae, 65
Olpidium viciae, 65
orders, names of, 18
Pasteur, 207
Penicillium, 30
Peronosporeae, 34
phagocytosis, 6
Phycomycetes, 30
Phycomycetes, classification of, 162
Phytophthora erythroseptica, 41
Phytophthora infestans, 41
Piptocephalis, 48
Plasmodiophora brassicae, 124, 125, 126
Plasmodiophoraceae, 121
plasmodium, mycetozoan, 139
Plassomyxa contagiosa, 100
Plassomyxa forma-maligna, 200
Plassomyxa, vital changes in, 103, 104
Plassomyxineae, 99
plasson, 5
Pleolpidium, 62
Plcurococcus vulgaris, 26
Polyphagus euglenae, 56
Polyphagus, nuclei of, 58
INDEX
229
Polysphondylium, 157, 158
promycelium, 45, 46
Protist, meaning of term, 1
protophyta, 17
protoplasmic motion, 8, 105
protoplast, 29
Pseudolpidium, 62
pycnoplasson, 90
Pythium, 34, 35
Pythium debaryanum, 35, 36
Pythium, nuclei of, 40
Pythium, parasites of, 36
Reticularia Lycoperdon, 133
Rhinosporidium Kinealyi, 161
Rhizidiaceae, 56
Rhodochytrium spilanthidis, 27, 29
Rozella septigena, 24, 34, 62
Saprolegnia, 31
Saprolegnia, parasites of, 34
sclerotium of Didymium Complanatum, 141
sclerotium, the mycetozoan, 141
Shewiokovdla, 161
smallpox, 168
Sorosphaera veronicae, 127
sorus -format ion, 63
sorus -formation in Synchytrium, 71, 80
species, definition of, 20
Sphaerita endogena, 67
Spirochaeta pallida, 179
Spirochaeta pallida, cultures of, 179
spirochaetes, 179
spirochaetes, in cancer, 197
Spirochaetes, in vaccinia, 172
Spironema pallida, 179
Spongospora scabies, 128
spore, application of word, 19
spores of fungi, 46
staining, intra vital, 14
starch, 22
Stemonitis, 136, 138
symbiosis, 50
Synchytriaceae, 68
Synchytrian nucleus, the, 78
Synchytrium and cancer, 191
Synchytrium alpinum, 69
Synchytrium aureum, 68
Synchytrium decipiens, 79, 91
Synchytrium endobioticum, 73, 81, 83
Synchytrium endobioticum, life -cycle of, 75
Synchytrium, generative chromidium of, 84
Synchytrium, of a thistle, 85, 88
Synchytrium stellariae, 71
Synchytrium succisae, 73
syphilis, 177
syphilis and cancer, 182
syphilitic ulcer, section of, 178
taxonomy, 16
terminology, 18
tissues, culture of, 10
tonoplast, 8, 25
Ulothrix zonata, 23
Urophlyctis, 61
vaccines and pro-vaccines, 208
Vaucheria sessilis, 23, 24
Virchow, 210
virus -filtration, 109
Volvox, 18
Woronina, 34, 62
zoochlorels, 51
zooxanthels, 51
Zygomycetes, 44
THE END
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