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editor.

COMPARATIVE MORPHOLOGY AND BIOLOGY

OF THE

FUNGI
MYCETOZOA AND BACTERIA

DE BARY

[4] a

Rondon
HENRY FROWDE

OXFORD UNIVERSITY PRESS WAREHOUSE

AMEN CORNER, E.C.

COMPARATIVE MORPHOLOGY AND BIOLOGY

OF THE

FUNGI
MYCETOZOA AND BACTERIA

BY

A. DE BARY

PROFESSOR IN THE UNIVERSITY OF STRASSBURG

THE AUTHORISED ENGLISH TRANSLATION BY

HENRY E. F. GARNSEY, M.A.

Fellow of Magdalen College, Oxford

REVISED BY

ISAAC BAYLEY BALFOUR, M.A, M.D., F.R.S.

Fellow of Magdalen College, and
Sherardian Professor of Botany in the University of Oxford

WITH 198 WOODCUTS

Oxford
AT THE CLARENDON PRESS
1887

[AU rights reserved ]

nn

PREFACE TO THE ENGLISH EDITION.

I po not deem it necessary to say anything in explanation of the reasons which
have led to the preparation of this translation of Professor de Bary’s book on the
morphology and biology of Fungi, Mycetozoa and Bacteria. It brings within reach
of all English-speaking students the most thorough and comprehensive treatise upon
these groups which has appeared in any language; and the picture that is presented
of the state of our knowledge of the subject at this time, along with the suggestions
and indications of the lines upon which further investigation is especially wanted, will,
it is to be hoped, not only instruct readers, but also stimulate them to research.

To render adequately some of the precise terminology has been a serious
difficulty in the translation. The terms which have been adopted are consistently
used, and the occasional notes, along with the ‘ Explanation of Terms’ which I have
added, should prevent all misconception of their signification. It must be remembered
that the definitions and synonymy given at the end of the book have reference to
terms only as they are used in the text; they are not exhaustive. The extension of
the original meaning of Berkeley’s term ‘ sporophore’ and its use as the equivalent of
the German ‘Fruchttrager’ is a prominent innovation to which attention may be
directed in this place..

Several friends have been so kind as to give me their opinion and criticism
upon questions of terminology, and I have specially to acknowledge suggestions from
Professor Bower, Mr. A. W. Bennett, Dr. S. H. Vines, and Professor Marshall Ward ;
for help in some difficulties I have to thank the author himself. .

I. B. B.
OXFORD: March 1, 1887.

PREFACE.

I pusLishep a work in the year 1866 entitled Morphology and Physiology
of the Fungi, Lichens and Myxomycetes as the second volume of Hofmeister’s
Handbook of Physiological Botany. This work was intended to give a systematic
and critical account of the state of our knowledge of the portions of natural history
indicated by the title at that time. It had its mistakes and its deficiencies; theindex _
too was omitted, but for this I was not responsible. At the same time it was
not without its value; it paved the way for further advances and was favourably
received. i +

Some years ago I was urged by many persons to prepare a new edition of my ”
work. Other occupations and duties long prevented me from setting about this task
and interrupted and delayed it repeatediy after it had been begun; and when
I addressed myself more closely to the work some four years ago, it soon became
apparent that a new edition in the strict sense of the word would not satisfy modern
requirements. Hence the progress of the work resulted in the production of a new
book, which can only be partially regarded as a new edition of the earlier one, though
this for brevity’s sake is always cited in the present work as the first edition,

The reasons for the change had their origin in the considerable additions to the
material to be discussed. Eighteen years ago it was comparatively easy to give
a detailed description of the state of our knowledge of the morphology and physiology
of the Fungi within a moderate compass. Since that time the amount of matter has
increased greatly, and with it the number of questions and controverted points which
have to be considered; an account which is not to be confined within the narrow
limits of a text-book readily assumes large proportions and renders division of labour

desirable.
The physiology of the Fungi has received more comprehensive treatment than

the morphology, partly in general treatises on vegetable physiology, those especially
of Sachs and Pfeffer, and partly in the extensive modern literature of the chemistry
of fermentation. There is no recent detailed critical survey of their morphology;
in giving such a survey in the following pages, with brief allusions only to strictly
physiological topics, I believe that I shall best meet both present requirements and
the wishes of most of my readers.

No comprehensive account of the morphology of any portion of the vegetable
kingdom, and least of all of the Fungi, can be satisfactory without constant reference
to the phenomena known as biological, that is to their habits of life and adaptations.

viii PREFACE.

These must therefore be handled at some length, and in their turn again lead up to
the consideration of questions of physiology.

I ought perhaps to have carried the change still farther, and have omitted a
variety of anatomical and histological details, the introduction of which was suitable
and necessary eighteen years ago, but which in the present state of botanical science
may be regarded as superfluous or at least not indispensable. Still they can do no
harm, and may possibly or even probably be of service. I have therefore taken
some matter of this kind from my former work, and added it to the main text of
the present publication in the smaller type employed for the description of some
other details. :

One change which I have ventured to introduce may and perhaps will be
objected to. It is, that I have omitted the section which treated of the origin of
the Fungi, Myxomycetes and Bacteria, and that I set out in all cases from the
assumption that these plants are like all other plants the product of germs, each
of which is derived from parents of the same species and owes its existence in every
species to processes of development in the parents or to organs belonging to them.
It is known that other views have prevailed with regard to the origin of the plants
described in this work, and are still entertained by a few persons. It may be
observed in passing that the early botanists, of whom mention is made in Ehrenberg’s
Epistola de Mycetogenesi, considered the Fungi to be merely lusus naturae and
no plants at all. There are some who still think that Fungi and Bacteria are
certainly plants, but that they are or may be produced by spontaneous or
heteromorphous generation (abiogenesis, heterogeny), that is from inorganic matter
showing only chemical predisposition to organisation, like crystals in the mother-lye,
or else from commencements which are organised but which proceed from organisms
that are not themselves either Fungi or Bacteria. The former of these two views
requires no further consideration in this place. The other will be discussed in
Chapter V, p. 270, in the special case of Sprouting Fungi and Yeast-fungi; it
assumes in general terms, that constituent portions of living cells belonging to
higher organisms, ‘vesicles, granules,’ the microsomata of modern terminology,
can continue an independent life after the death of the living body of which.
they formed a part, and develope under favourable conditions into Fungi and
Bacteria. These forms may then develope their specific germs, and a progeny
from these germs specifically resembling the parents. H. Karsten and his adherents
represent views of this kind, and A. Wigand has supported them at the present day.
Their most logical development is to be found in A. Béchamp’s theory of the micro-
zymes. These are very minute bodies, ‘granulations moléculaires,’ which are
contained in the substance (protoplasm) of animals and plants of the most different
kinds and grades of organisation, and not only develope independently after the
death of the parent-organism, but enjoy an almost unlimited duration of vitality,
since they may lie during entire geologic periods in such a rock as chalk, and yet
retain the power of development. These microzymes give rise in a suitable medium
to Bacteria, Sprouting Fungi, and similar forms, and since the localities in which
they originate are of very frequent occurrence they are to be found everywhere.
Béchamp published his theory in the Reports of the Academy of Paris twenty years ago;
he reproduced it in the Transactions of the Medical Congress at London in 1881, and

PREFACE. ix

in a large new work, Les Microzymas dans leurs rapports avec ’hétérogénie, l’histio-
génie, la physiologie et la pathologie, Paris, 1883.

Theories of the kind here described, and others more or less like them, are
constantly recurring from time to time on the subject of the origin of the Fungi and
Bacteria. They appeared in earlier times with still greater breadth of application.
Fifty years ago it was believed that not only minute organisms but that Fungi of the
size of the Uredineae were produced from the altered substance of other organisms,
in the case of the Uredineae from phanerogamous plants; two hundred years
ago maggots were supposed to be bred from putrid flesh. It is easy to understand
how such ideas of spontaneous generation should have been prevalent in ancient
times. Even their repeated recurrence in modern times and with our modern know-
ledge is also capable of explanation. It must be assumed that organisms did once
come into being of themselves without parents, being produced from organisable but
not yet organised matter. It must moreover be allowed, that this may still happen at
any moment and perhaps does actually happen; its impossibility cannot be proved.
To produce actual proof of an original formation of a living being is a matter of the
highest interest, and has as powerful attraction for the biological investigator, as the
prospect of producing the homunculus in the phial for the alchemist. But the
experience of centuries has shown that whenever the homunculus really appeared in
the flask, it proved to be a small imp which had been secretly introduced into it from
without ; and speaking seriously, the result was always of this kind. In every single
instance exact investigation has shown that the organisms which were supposed to
have had no parents proceeded from germs produced from parents of the same species
as themselves; it has also shown how they were formed and whence they came.
Those who maintained that direct proof had been given of generation without parents
have been driven back step by step into narrower territory, and upon minuter and at
last upon the minutest objects, from simple inorganic matter to the organised mini-
mum, the ‘atome structuré vivant’; in other words they were reduced to seek their proof
where it is still most difficult to say whether it is to be found or not. This is what
has happened in all researches into the origin of the Fungi, as soon as each individual
case was rigidly examined. We have had ocular demonstration of the fact since the
year 1860, through the labours especially of Pasteur and his school. That there is
no generation without parents is therefore a maxim of experience; it is in distinct
accord with the present state of our knowledge, after making allowance for all
conceivable possibilities, and we must set out from this principle in a book which is
concerned with real knowledge.

There is not much to be said by way of preface with regard. to the plan of this
work. I have endeavoured to make my remarks intelligible even to those who are
only beginning the study of the Fungi, but I have assumed that my readers are
masters of such a previous general knowledge of botanical science as is to be obtained
by a course of study in a University, or by the use of good text-books. The reader
is here referred to such works, especially to Sachs’ Text-book and Lectures, and
Goebel’s Outlines, and also to Prantl’s and Luerssen’s smaller compendia, and among
works not in German to Van Tieghem’s Traité de Botanique.

A few descriptions only of individual Fungi will be found scattered through the
volume; others must be sought in our at present imperfect floras, in Saccardo’s

x PREFACE.

Sylloge Fungorum for example, in Winter's Die Pilze Deutschlands, P. A. Karsten’s
Mycologia Fennica, and Fries’ more important publications, which latter must always
be indispensable; books also of descriptive lichenology must be consulted. The
new edition of Leunis’ Synopsis by A. B. Frank, and in its special line Frank’s Pflan-
zenpathologie, are works to be recommended to the student. I must not be supposed
to express an unfavourable opinion of other works because I do not mention
them; my only purpose is to point out some books which will be of service
to those who require direction in their reading.

I have endeavoured to make myself as well acquainted as was possible with the
special literature of my subject and to draw it into my service. I have made some
use even of publications which appeared at the close of the year 1883 and the
beginning of 1884 while my book was being printed. That some particulars have
been omitted altogether, or been forgotten for the moment in the preparation of some
of the sections, is what I should have expected beforehand, even if I had not
subsequently noticed their omission. I must plead in excuse the extraordinarily large
number of mycological communications of every possible size which have been
published during the last twenty years.

The number of publications on the Fungi is so large that it was impossible to
quote them all, and to have done so would have transgressed the limits of practical
utility. The more important references given in the text will in every case show
where further details are to be obtained, especially with the assistance of Hoffmann’s
Mycologische Berichte from 1865 to 1872, and Just’s Jahresbericht, which has
appeared regularly since 1873. Special notices of the literature of the subject will be
found in the separate sections of the work.

The illustrations are for the most part the same as those in the earlier work. A
certain number are new and drawn by myself; a smaller portion have been taken
from other authors whose names are in every case given in the explanations appended
to the figures. I express my warmest thanks for the permission to use these
illustrations, and no less warm thanks to all those who have lightened my labours by
their communications and by assistance of other kinds.

A. pz BARY.

STRASSBURG: June 30, 1884.

TABLE OF CONTENTS.

FIRST PART. FUNGI.
DIVISION I. GENERAL- MORPHOLOGY.

CHAPTER I. HisToLoGIcAL CHARACTERISTICS.
SECTION

I. General construction. Hyphae. Growth-forms: Filamentous Fungi,
Fungus-bodies, Sprouting Fungi (Chytridieae, Laboulbenieae)
II. Structure of Fungus-cells : Protoplasm, Cell-nuclei, Cell-contents

III. Cell-membrane: Structure, Material composition, Excretion of calcium:

oxalate z
Remarks. Literature .

CHAPTER II. DIFFERENTIATION OF THE THALLUS,

1. General Survey.
IV. Mycelium and sporophore

2. Mycelium.

V. Mycelia. Filamentous mycelium. Haustoria
VI. Mycelial membranes
VII. Mycelial strands (Rhizomorphae, eae irises)
VIII. Sclerotia : Structure, origin, germination
Details. Historical remarks R . 8
IX. Sclerotioid bodies : nis me states: Xyloma
Literature
3. here
X. General characteristics 2 5 5 . 5 5 ä 5
XI. Simple sporophores 5 hi $ = r é . .
XII. Compound sporophores. General differentiation. Course of growth.
XIII. Structure of mature compound sporophore .

CHAPTER III. Spores or Funct.
XIV. Introduction. General characteristics and distinctions

I. Development and Scattering of Spores.

XV. General phenomena of development . . . $ 3 5 :
XVI. Intercalary and acrogenous spore-formation. Basidia. Sterigmata .

PAGE

17

18
21
22
30
40
42
43

45
46

48
57

59

6c
61

xii CONTENTS.

SECTION

XVII. Dissemination of acrogenously formed spores. Abscision. Abjection.

Disappearance of the sporiferous structure. . . . .
XVIII. Endogenous spore-formation :
(2) Sporangia of Phycomycetes . 2 i A B

XIX. (2) Asci. N a 2 ö 5 é R é a a ‘

XX. Dissemination of endogenously formed spores :
(a) Phycomycetes A ‘ F . i ‘ ‘ E ä
XXI. (4) Ascogenetic spores. Ejection. Mechanical arrangement for
ejection of spores. Simultaneous and successive ejection. Mechanism
of simultaneous ejection. 3 . & A a .
XXII. Puffing in Discomycetes i i
XXIII. Peculiar mode of ejection in Pyrenomycetes .
XXIV. Force of ejection
XXV. Reported peculiarities in Lichen fungi
XXVI. Successive ejection from asci . . . . . i . x
XXVII. Solution and swelling of asci . . q N 5 A ‘i r .
XXVIII. Maturation of ascospores after ejection . . & . . . .
XXIX. Combinations of different kinds of spore-development ; sporidesms
II. Structure of ripe Spores.

XXX. Spore-membrane. Exosporium, episporium, endosporium. Germ-
pores. Gelatinous envelopes and appendages.—Protoplasm, nucleus,
content.—Swarm-spores . . : . : . . . .

III. Germination of Spores.
XXXI. Tube-germination and sprout-germination.—Germ-tube. Primordium
of the mycelium. Promycelium and sporidia . 5 . 5 n
Historical remarks on Chapter III . . . . . .

PAGE

68

73
76

81

84
89
gI
or
93
93
96
97
98

99

115

DIVISION II. COURSE OF DEVELOPMENT OF FUNGI.

CHAPTER IV. INTRoDUcTıon.

XXXII. General course of development in Algae, Mosses, Ferns, and Phanero-
gams. Homologies and affinities. Form-genera and form-species
in Fungi. Tulasne’s pleomorphy. Gradual recognition of the
course of development and of the homologies in Fungi. Main or
Ascomycetous and other series . ‘ . . . . .

XXXIII. Closer consideration of the course of development of the higher
p:ants. Archicarp; fructification.—Spore, sporocarp, sporophyte.—
Sexual and asexual segment of the development. Homology of a
member of the development independent of its sexual function.
Interruption and restoration of the homologies.—Alternation of
generations—Homology interrupted and not restored . .

XXXIV. Agreement of the course of development of the Fungi with that of
plants which are not Fungi. Meaning of Ben. Misunder-
standings and the way to remove them. .

119

121

126

SECTION

XXXV.
XXXVI.

CHAPTER V. ComparaTIVE REVIEW OF THE SEVERAL GROUPS.

XXXVII.

XXXVIII.

XXXIX.

XL.

XLI.

XLII.

XLII.

XLIV.

XLV.

CONTENTS,

Terminology. Spores. . Gonidia, &c.
Review of the chief groups of Fungi

Peronosporeae.
Ancylisteae.
Monoblepharis.
Saprolegnieae.

Mucorini.
General course of development

Zygospores. (a) Mucoreae and Chaviodiiene ® Bipamentalidese=
Azygospores . . .

Typical gonidiophores. une Chisötlaiieie, Tipeoeepkalls
and Syncephalis > “Gi ae ee ee POY 8

Accessory gonidia. Acrogonidia (chlamydospores, stylospores).
Choanephora.—Gemmae.—Serial gemmae, sprout-gemmae

Doubtful Mucorini. Historical remarks. Literature

Entomophthoreae.

Chytridieae.
Common characteristics of the present group of Chytridieae. Spor-
angia. Resting spores . : . n 5
Rhizidieae —Polyphagus. Less well known forms
Cladochytrieae x ‘ ‘i : 5
Olpidieae
Synchytrieae
Comparative review
Doubtful Chytridieae. Tetrachyrium Hapalecysts
Literature . . . E

Protomyces and Ustilagineae.

Protomyces . 5 . . . e e 8
Ustilagineae. Conformation. Compound sporophore
Development of resting spores . . > ce & ‘ ; é
Structure and germination of resting spores A S a ti

Gonidia of Tuburcinia and Entyloma
Course of development and homologies

xiii
PAGE

128
132

132

139

140

141

162

166

170
171

171
172
174
176
179
180

xiv

SECTION
LIX.

LX.
LXI.
LXxIl.

LXIII.

LXIV.

LXV.

LXVI.

LXVII.

LXVIII.

LXIX.
LXX.
LXXI.
LXXII.

CONTENTS.

Ascomycetes,
GENERAL CHARACTERS. SPOROCARPS.
Structure of sporocarp. Apothecium, perithecium, cleistocarp
Apothecia . . . . F . R 5 A & A
Perithecia

Cleistocarpous fits Elbe N = Oaygena: —Myri-
angium. ‘

ORIGIN OF SPOROCARP.

Review of the main facts. 1. Eremascus.—2. Genera which have at
first a distinct archicarp with no distinct envelope.—3. Polystigma
with archicarp in the primordium of the sporocarp.—4. Xylaria and
allies with a temporary Woronin’s hypha.—Genera without a distinct
archicarp

Separate descriptions.

. Erysipheae

. Eurotium .

. Penicillium . r

. Gymnoascus. Ctenomyces

. Ascobolus

. Pyronema . 5

. Sordaria. Melanospora .

. Collemaceae ‘i

. Forms with archicarp imperfectly eamined

. Polystigma R

11. Xylarieae

12. Sclerotinieae

13. Pleospora herbarum

14. Claviceps, Epichloe, Cordyeeps, Neetrin and others

15. Ascodesmis . . .

16. Sphyridium, Bacaımyess; Cihdania ai arliers,

Soosonzuen

Early investigations into the development of the sporocarp in Lichens .

THE COURSE OF DEVELOPMENT IN ASCOMYCETES.

Statement of facts. Species without gonidia ; others with a regularly
intercalated formation of gonidia. Different forms of gonidia in the
same species. Microgonidia and megalogonidia. Pycnidia, pycno-
spores, stylospores.— Examples of ar which have been fully
examined

Homologies of the members of the deli in N
Controversy regarding the sexual organs

DETERMINATION OF IMPERFECTLY KNOWN ASCOMYCETES,
The points on which the question turns
Archicarps, sporocarps
Spermogonia and spermatia
Doubtful spermatia
Gonidia, gonidiophores, Eye TE: R
Combinations of different forms. Examples of the kind

197

201
203
204
206
206
208
210
211
214
215
216
218
220
220
221
221

222

223

231

238
239
240
242
244
248

SECTION

LXXIII.

LXXIV.

LXXV.
LXXVI.
LXXVII.
LXXVIII.

LXXIX.

LXXX.
LXXXI.
LXXXII.
LXXXIN.

LXXXIV.

LXXXV.
LXXXVI.
LXXXVII.
LXXXVIII..

LXXXIX.

XC.

XCI.

XCIl.
XCIII.
XCIV.

CONTENTS.

Occurrence of known or supposed members of the development of
some species outside the normal connection. Tendency of these to
constantly similar an Hence a Pa reduction or
splitting of a species

Determination of organs of propagation sihich have bea Since to
be rudimentary .

Literature of sections LIX—LXXIV.

DOUBTFUL ASCOMYCETES.

Introduction. Helicosporangium. Papulaspora. Laboulbenieae .
Exoascus
Saccharomyces . “ 5 a ‘ R 3
Affinity between Exoascus and ende Possible relations

of the latter group to the Ascomycetes .
Confusion between the ‘ Yeast-plants’
Literature .

Uredineae.

Aecidia-forming and Tremelloid Uredineae. Sporocarps (aecidia)
and spermogonia of the aecidia-forming er Course of de-
velopment of Endophyllum

Aecidia-forming Uredineae with gonidia : feltosenes uredo .
Uredineae with imperfectly known course of development
Tremelloid Uredineae R A

Relationship between Uresinege and Abkonfjeers

Literature .

Basidiomycetes.
Introduction

HYMENOMYCETES.

Conformation of unveiled sporophore a
Veiled sporophore. Velum. Annulus. Volva
Structure of full-grown sporophore

Hymenium. Cystidia. Basidia

GASTROMYCETES.
Comparative account of the differentiation of the sporophore

Special morphology, history of development and anatomy of the
same : 3 = & ;

COURSE OF DEVELOPMENT AND AFFINITIES OF BASIDIOMYCETES.

Course of development of perfectly known form. Exobasidium,
Tremellineae, Typhula, Coprinus, Agaricus melleus, Crucibulum
and Cyathus, Sphaerobolus

Gonidia of Basidiomycetes which have ben occdaniy eh 2
Imperfectly known and doubtful gonidia

Homologies and affinities of Basidiomycetes

Literature .

xv

PAGE

274
279
282

283
285
285

286

287
289

297
300

308

312

328
331
333
337
341

xvi CONTENTS.

DIVISION III. MODE OF LIFE OF FUNGI.

CHAPTER VI. PHENOMENA OF GERMINATION.

1. Capacity of germination and power of resistance in Spores.
SECTION

XCV. Duration of capacity of germination in spores. Resting state.
Power of resistance to mechanical injuries, withdrawal of water,
extreme temperatures

2. External conditions of germination.

XCVI. . a 5 R . : : 5 5 : 2 . . Fe

CHAPTER VII. PHENOMENA OF VEGETATION.

1. General conditions and phenomena,

XCVII. Conditions affecting growth. Temperature . A . . .

XCVIII. Nutrient substances. Other chemical conStituents of the ee.
Effects of Fungi on the substratum. Fermentations, oxidations.
Ferment-excretion . R : 5 5 R R

2. Nutritive adaptation.

XCIX. Distinction of 1. pure saprophytes, 2. facultative parasites, 3. obligate
parasites either a, strictly obligate, or 4, facultative saprophytes .

3. Saprophytes.

4. Parasites.
CI. Adaptation between parasite and host. Predisposition of host. Endo-
phytic and epiphytic parasites 5
CH. Attack of parasite on host 5

CIII. Growth of parasite after it has seized on the host ande reactions of the
host on the parasite. Destroying and transforming parasites

PARASITES ON ANIMALS.
CIV. Facultatively parasitic Aspergilli and Mucoreae; obligately parasitic
Entomophthoreae, Laboulbenieae, Cordyceps, Botrytis Bassii
CV. Imperfectly known parasites on animals : Saprolegnieae
CVI. Fungi of skin-diseases A
CVII. Actinomyces. ‘Chionyphe Carteri’ e

PARASITES ON PLANTS.
a. Facultative parasites.

CVIII. Fungi of rotting fruit. Sclerotinieae. Pythieae. Nectriae. Hartig’s wood-
destroying Hymenomycetes wl’ Ron rah: te cfs, et 4g

PAGE

343

349

352

353

356

357

377

379

SECTION
CIX.

CX.
CXI.
CXII.

CXIII.

CXIV.

CXV.
CXVI.

CXVII.

CONTENTS,

b. Obligate parasites.

Facultatively saprophytic : Peronosporeae, Mucorini, Ustilagineae, Exo-
basidium, Myxomycetes ; strictly obligate: Peronosporeae, Erysi-
pheae, Uredineae, &c. . A ‘ $ . 5 a A R

Autoecism and metoecism . : 5

Growth and extension of parasites in kübsteiee of — iilants

Behaviour of these parasites to separate tissues aad to the parts of the
‘cells of the host . 7 A 3

Reactions of the plants Sale . . 7 é E 5 n

Lichen-forming Fungi.

Formation ofthe Lichen-thallus by the growing together of certain Algae
and Ascomycetes and a few Hymenomycetes which attackthem. Enu-
meration of Lichen-forming algal forms as at present known , «

First beginning of the Lichen-thalus . . . . 8 .

Conformation and structure of the Lichen-thallus. Fruticose, foliaceous
and crustaceous forms. Distinctions in anatomical structure: 1.
Heteromerous thallus. 2. Graphideae and similar forms. 3. Granular
crustaceous thallus of Thelidium and others. 4. Coenogonium-form.
5. Collemaceae or Gelatinous Lichens. 6. Hymenomycetous Lichens

Soredia . . 3 . a . . :

Pseudo- hchens Historient pamneaice Literature . 2 n P .

SECOND PART. MYCETOZOA.

CHAPTER VIII. MORPHOLOGY AND COURSE OF DEVELOPMENT.

CXVIIL.
CXIX.
CXX.
CXXI.
CXXII.

CXXIIL

CXXIV.

CXXV.

[4]

Myxomycetes.
Spores. Germination. Swarm-cells . . . Sa fe ot
Plasmodia . . . Re < i A i i . ri
Transitory resting states. Cysts. Sclerotia. . . . .
Development of sporophores and sporangia . . A 7

Structure of mature sporophores and sporangia ; drohen of ee
tieae ; simple sporangia ; aethalia . . . . . . ai

Acrasieae.

Affinities of the Mycetozoa.

Doubtful Mycetozoa,

Bursulla. Vampyrellae. Nuclearia. Plasmodiophora . . .
b

xvii

PAGE

385
386
389

392
394

395
398

401

415
416

421
423
427
429

434

441

446

xviii CONTENTS.

CHAPTER IX. MobeE OF LIFE OF MYCETOZOA.

SECTION ‘PAGE

CXXVI. Conditions of germination . . Er nn 448
CXXVII. Phenomena and conditions of en Causes of movement of

plasmodia. Enclosing of solid bodies. . : & s - .449

CXXVIII. Process of nutrition . : e & B 7 3 : ö - 451

Literature . 2 e e 5 3 j ö % . R . 453

THIRD PART. BACTERIA OR SCHIZOMYCETES.

CHAPTER X. MoRrPHOoLoOGY OF BACTERIA,

CXXIX. Structure of cells. Cell-aggregates and growth-forms s v0. 454
CXXX. Course of development. Endosporous and arthrosporous forms. De-

velopment of endospores. Special description of some Bacilli . 459

CXXXI. Development of arthrosporous forms . . . 2 B a - 468

CXXXII. Controversy respecting species in Bacteria A n we . 472

CXXXIII. Systematic position of Bacteria. 2000200. 44

CHAPTER XI. Move or LIFE OF BACTERIA.

CXXXIV. Capacity and conditions of germination in spores s 5 a » 476
CXXXV. General conditions and phenomena of vegetation.—Temperature.
Nutrient substances. Oxygen. Aerobia, and anaerobia. Effect
of substances not serving as nutrients. Oxygen and nutrient sub-

stances as inciters of movement . 7 . . . A . 478
CXXXVI. .Special vital adaptations. Saprophytes. Parasites. Parasites on
plants. Parasites on animals. Exciting causes of disease. Life-
history of Bacillus Anthracis as an example of facultative parasites.
Doubtful obligate parasites ; Spirochaete Obermeyeri; Nosema

Bombycis.—General remarks on Bacteria which excite disease . 481
Literature . . 5 . é ‘ x . . . . - 489
EXPLANATION OF TERMS s ‘ E ‘i ‘ s 3 ‘ R . 491

INDEX . . . . 3 7 . ® & R s 4 5 . + 503

ERRATA.

Page 1, line 15, for rudimentary branch read branch-primordium.
» 9, line 8 from bottom, for Muscaria read muscaria.
a » line 3 from bottom, for erinaceus read Erinaceus.
» 18, line 2, for or read and.
» 29, lines 1 and 8, for fructification read sporophore.
» 34, line 5 from bottom, for commencemet read commencement.
„» 59, line 5 from bottom, for Coprineae read Coprini.
» 51, line 4, after Clavarieae insert Calocera.
» », line 15 from bottom, for Coprineae read Coprini.
» 57, line 16 from bottom, for Helvetia read Helvella.
» 64, line 22, after sterigma read , as in Coprinus.
» 76, line 12, for orientated read originated.
» 99, line 5, for sporiderms read sporidesms.
„ 130, line 4 from bottom, for rudimentary read commencing.
„ 162, line 5 from bottom, for tubular-rhizoid processes, read tubular rhizoid-
processes.
» 177, line 4 from bottom, for sometines read sometimes.
» 181, line 7, for Urocystis vead Ustilago.
»» 192, line 6 from bottom, for Verrucariae read Verrucaria.
» 244, last line, for polytrichum read polytricha.
», 268, line 3, for Mycodermain, read Mycoderma in.
» 277, line 7 from bottom, for sempervivi zead Sempervivi.
», 286, last line, for 53 read 48.
3, 306, line 14, for violacea read foliacea.
»» 330, line 12, for 25°C. read 25°C.
>> 349, line 9 Jor winter, of read winter of.
» 352, note 2, for 294 read 262.
» 308, lines 25 and 26, for fir read silver-fir.
» 376, line 17, for Mentagrophytes, Rob.; read Mentagrophytes, Rob.);
» » line 18, for pityriasis versicolor‘). read pityriasis versicolor?.
» 391, line 2 from bottom, for hypodites read hypodytes.
» 399, line 8 from bottom, for peridermis read periderm.
», 406, line 16 from bottom, for malacca read malacea.
» 427, line 18, for Stemonites read Stemonitis.
» 428, line 5 from bottom, for homogenous vead homogeneous.
» 434, lines 18 and 19, for serpula read Serpula.
» 441, line 17 from bottom, for serpula read Serpula.

Y

Frrest Parr.

FUNGI,

DIVISION I. GENERAL MORPHOLOGY.

CHAPTER I. HISTOLOGICAL CHARACTERISTICS.

Section I. The thallus, which in most Fungi is the whole body of the plant
not serving directly as an organ of reproduction, begins as a tubular germ-cell
(germ-tube, Keimschlauch) which, by continued growth progressing in an apical
direction accompanied by repeated formation of lateral branches, developes into a
branched body of cylindric thread-like form, the pa. Both growth and branching
follow the laws which prevail generally in the vegetable kingdom. The branching is
usually monopodial, in a few cases only it is dichotomous, as in Botryosporium, species
of Peronospora, and some Mucorini.

In some groups, especially the Saprolegnieae, Peronosporeae and the Zygo-
mycetes, the thallus or hypha of the Fungus, like the thallus of the Siphoneae, is
an unsegmented branched tubular cell up to the time when organs of reproduction
are formed. But in the great majority of cases it becomes a branched row of cells
owing to the incessant formation of transverse walls concurrently with the growth
of the hypha at its apex. The segmentation either takes place only in the apical
cell for the time being and at the place of insertion of the rudimentary branch,
so that each branch is made up of an apical cell and segment-cells of the first order
only, as in Penicillium? and Botrytis cinerea, or new intercalary partition-walls are
formed in the segment-cells of the first order.

In the more simple Fungi the branched hypha alone constitutes the thallus;
such forms are termed Hyphomycetes, Filamentous Fungi (Fadenpilze), or
Haplomycetes?. The body of the largest Fungi, the Mushrooms and Lichens of
ordinary parlance, are also composed of hyphae, but their ramifications meet and
cohere to form larger aggregates. Such a body, which appears as if formed by the
union of Filamentous Fungi, may be termed a compound Fungus-body (zusam-

1 Löw in Pringsheim’s Jahrb. VII. p. 473.—Brefeld, Schimmelpilze, II. p. 27.
2 From the Greek word damAods, meaning simple.

[4] B

2 DIVISION I,—GENERAL MORPHOLOGY,

mengesetzer Pilzkérper) or simply a Fungus-body to distinguish it from that of
the simple Filamentous Fungus. Both are growsh-forms (Wuchsformen) comparable
with those growth-forms in the higher plants which are known as the tree, shrub,
and herb, Many species appear only in the filamentous form, as succeeding
chapters will show; others assume both forms according to their stage of develop-
ment and external conditions ; all have the filamentous form in their earliest stage.
It is obvious that intermediate forms will be found between these two chief ones.

It has been assumed above that a hypha or a Filamentous Fungus is the product
of a single germ-cell, and this is often actually the case. It has been repeatedly
shown that even a compound Fungus-body may be composed of the ramifications
of a single filament proceeding from a single germ-cell. But this is not always
the case, or at least cannot always be proved, owing to the frequent coalescence
of similar hyphal branches with one another (Fig. 1), which takes place in the

a
IF \ "
N, \
FIG. ı. Germinating gonidia of Nectria (Spicaria) Solani, FIG. 2. Clamp-connections of the my-
Reinke ; z developing into an isolated hypha, in the rest the celium of Hypochnus centrifugus, Tul.

hyphae have coalesced. Magn. 390 times. Magn. 390 times.

following manner :—the lateral wall or the extremity of a branch or of a segment-~
cell of the branch places itself on another branch or cell, and the membranes of
both disappear at the point of contact, so that the cavities and protoplasmic contents
of the two cells become united into one. Coalescence in this way may take place
between the branches of the same hypha, and also between such as are growing
together but were originally distinct, being the product of distinct germ-cells. The
forms which result from such coalescence are very various; H-shaped cross links or
bridges, loops of various form and number, even network of many narrow meshes are
found. One curious form must be mentioned here, the clamp-connections (Schnallen-
verbindungen), first observed by Hoffmann (Fig. 2). They occur only on hyphae with
transverse segmentation, and chiefly in the Basidiomycetes (many Agaricineae, species
of Polyporus, Typhula, Hypochnus, Cyathus, Hymenogaster, &c.). A clamp of this
kind when fully formed is usually a nearly semicircular protuberance like a short
branch which springs from one cell close to a transverse wall, and is closely applied
to the lateral wall of the adjoining cell in such a way that the transverse wall cuts
the middle of the plane of contact at a right angle. Sometimes the protuberance
does not lie close on the lateral wall at all points, but forms an eye-hole. Brefeld
observed the origin of these formations in Coprinus, and found that the protuberance
extends itself from the one of the two adjoining cells to the other, and then
coalescence takes place, so that the two cells enter into open communication with

CHAPTER I.—HISTOLOGICAL CHARACTERISTICS. 3

one another through the protuberance, and finally the protuberance is separated
from the cell on which it first arose by a new wall which usually coincides with the plane
of the lateral wall. The protuberance generally continues in open communication
with the second cell, with which it coalesced; but here too subsequent separation
is sometimes, though seldom, effected by the formation of a wall, and it is only to
this exceptional case that Hoffmann’s original term ‘clamp-cells’ is properly suited.
In Coprinus according to Brefeld the first cell, the cell which puts out the
protuberance, is always the one on the apical side of the transverse wall. In this
case therefore the whole structure is formed almost exactly in the reverse way to
that which is suggested by its appearance when fully formed; whether this is so
in all other cases has yet to be ascertained.

The growth of the compound Fungus-body, so far as it depends on the
formation of new cells and not on the expansion of the old, is due simply to the
growth in length of the united hyphae and to the formation of new branches on
them; these branches are formed partly on the surface of the body, partly in its
interior, where they thrust themselves in between the branches previously formed.

In the fully developed state of these compound forms it is in most cases easy
to see the fine fibrillation due to their construction out of hyphae; the course of
single hyphae and their ramifications may often be followed with the aid of the
microscope for considerable distances, whether they lie parallel to one another or
whether they cross one another repeatedly and are intertwined.

In other cases the entire thallus or separate parts of it appear to have an entirely
different composition. Here the tissue when fully formed consists of isodiametric
roundish or polyhedral cells, and especially in thin sections no longer appears to be
an arrangement of hyphae, but resembles the ordinary parenchyma of the higher
plants. Examples of this tissue are to be found’in the pileus of Russula and of
Lactarius, in the rind of the peridium in many of the Lycoperdaceae, in many sclerotia,
in the stipe of the Phalloideae, in many Lichens, and in some other cases. But if we
examine this tissue more closely and follow the history of its development, we see
plainly that it is really formed from and consists of hyphae, and that it owes its parenchy-
matous structure simply to the firm union of the hyphae, and to the form, expansion,
and displacement of their cells. The parenchyma of the higher plants is formed by
cell-division, the partition-walls as they successively arise being placed in turns in
one of three or two directions in space. From this difference in origin the Fungus-
tissue of which we have been speaking is distinguished by the name of pseudo-parenchyma.
Successive cell-divisions in two or three directions occur only exceptionally in the
formation of the thallus of the Fungi, as in pycnidia and perithecia (on this see
Division IT).

The non (Verbindung) of the hyphae to form the compound Fungus-body is for
the most part brought about by their zz/erweaving (Verflechtung) one with another,
and the direction and closeness of the weft vary according to the species. The
hyphae of the flocky felt-like tissue of Polyporus fomentarius’, of Daedalea, of the stipe
and pileus of the Amaniteae, of the medullary layers of many Lichens, &c. are loosely
woven, leaving broad interstices usually filled with air; those of the firm tissue, often

1 Amadou of commerce.
B 2

4 DIVISION I.—GENERAL MORPHOLOGY.

hard as horn or wood, in the dark rind of the dry Pyrenomycetes, of the Tuberaceae, of
many sclerotia, &c., leave scarcely any intercellular spaces. Every intermediate stage is
to be found between the loose accidental intertwining of the socially growing Hyphomy-
cetes and the firm structure of the Fungi which have a definite form, and states
the farthest apart from one another sometimes occur in the same species.

When the hyphae run parallel to one another, as in the stipe of Agaricus Mycena,
Coprinus and other species, their connection may be brought about by cementation
(Verklebung) or concrescence (Verwachsung) of the membranes, and in the same way
they often gain much firmness where they are interwoven with one another. In hard
tissues, as the rind of many non-fleshy Fungi, and in the masses of gelatinous tissue
described on page 9, the outer surfaces of the hyphae are often inseparably grown
together, or are cemented together by a narrow slip of a firm homogeneous substance ;
in fleshy Fungi the hyphae are often united by an intervening substance which softens
in water and allows them to be artificially separated. This cementing substance
may be called zntercellular substance. Whether it is to be regarded as a part of the
cell-membranes themselves or as an entirely distinct body from them, is a question
which in the case of the Fungi has not yet been specially examined ; there is therefore
the léss ground for assuming other laws than those which prevail in the histology of
other plants. Lastly, the coalescence above mentioned of branches originally distinct
also adds to the firmness and solidity of the compound Fungus-body ; its occurrence
is shown in fleshy and gelatinous species by the frequency of H-shaped connections,
though no special researches have been made into their mode of formation.

Of the exceptional cases referred to above in which the Fungus-thallus is not
formed of hyphae, the first to be noticed
is that of the forms recently termed by
Nageli Sprouting Fungi (Sprosspilze). This.
name, like that of Filamentous Fungi, indi-
cates a growth-form; and this is the only
form in some Fungi, as in the species of
the genus Saccharomyces known as Yeast-
fungi, or it is peculiar to particular states of

eg other species which otherwise appear as fila-

mentous or compound forms. In the latter

Fic. 3 Saccharomyces Cerevisiae; a cells before Cases it may be a matter of doubt, for reasons

SO et dere in the orden auctbarine to be hereafter discussed, whether the sprout

a saa is to be regarded as a vegetative or as a
reproductive organ,

The characteristic features of the Sprouting Fungi are as follows (Fig. 3). A
cell grows to a certain size and shape, the latter being usually spherical or somewhat
ovoid, and puts out an excrescence or sprout which remains connected with it by a
narrow base; this new formation is of the same nature as the parent-cell and is
separated from it by a transverse wall either before or after it has reached its proper
size. The process of sprouting may be repeated in the daughter-cell and in every
succeeding generation, the number of which is unlimited in presence of sufficient
nutriment. The number of sprouts that can be produced by each active cell and the
spots at which they appear are not certainly determined, though with regard to the

@ [2
ur C*

ce

CHAPTER I.—HISTOLOGICAL CHARACTERISTICS. 5

latter it is possible to give certain rules in individual cases; as a rule the sprouts may
arise simultaneously at several spots in the mother-cell, or one after another from the
same spot. If all the generations of sprouts continue united to one another, it is
obvious that their combination simply forms an irregularly branched hypha, which is
distinguished from ordinary segmented hyphae only by the constriction at the narrow
„point of insertion of the sprout-cells. This is in fact the condition in which the cells
remain as long as they are not disturbed; but eventually the full-grown sprouts
separate easily from one another, and a slight movement leaves only isolated sprouts
or small aggregates of them.

The second exception is found in those simplest forms of the Chytridieae, in
which the entire thallus consists of a single round cell which ultimately produces
spores; the less simple species of this group are allied by their structure to the
unicellular Filamentous Fungi described in sections XLVI-L.

The Laboulbenieae may perhaps be reckoned as a third exception, but their
character is still very imperfectly known (see Division II).

The view given above of the structure and growth of the thallus of the
Fungi has been already distinctly indicated in Ehrenberg’s Epistola de Mycetogenesi
(Nov. Act. Acad. Nat. Cur. X); it is also clearly expressed in Vittadini’s Monogr.
Lycoperdineorum (Mém. Acad. Turin. Ser. II, V, p. 146, 1841); and the views of
later writers (Montagne, Esquisse organographique, &c. sur les champignons, Paris,
1841, German edition, Prague, 1844, and Schleiden, Grundz. 3rd edition, II, p. 34)
are in accordance with it. Schleiden, and Unger after him (Anat. u. Physiol. d.
Pflanzen, p.149), call the weft of distinct hyphae felted tissue, ‘tela contexta.’ Thoroughly
to establish and work out this view required fresh anatomical investigations, and to
these Bonorden and Schacht have given the chief impulse and contributed the first
more important materials. See Bonorden, Allgem. Mycologie, Stuttg. 1851, and
Schacht, Die Pflanzenzelle, p. 134. ;

On the clamp-connections see Hoffmann in Bot. Ztg. 1856, p.156; Tulasne, Carpol.
I, 115; Bail in Hedwigia, I, 96, 98, &c.; Brefeld, Unters. über Schimmelpilze, III,
especially p. 17; Eidam in Cohn’s Beitr. z. Biol. Bd. II, 229.

The distinction of pseudo-parenchyma or apparent parenchyma was introduced
by myself in the first edition of this work. The term may be retained as it has become
familiar ; but it should be remembered, that it ought only to be used to indicate the
appearance of the close short-celled tissue of the Fungus with reference to the ordinary
conformation of the parenchyma of the higher plants. If the latter tissue is charac-
terised not, as is most usual, by the form of its cells, but by their structure and by
the functions indicated by their structure, then the pseudo-parenchyma is neither
more nor less to be compared with it than any other aggregate of cells in the Fungus
which serves for metabolism.

The term Sprouting Fungus may be used as a general expression for the growth-
form which it designates. As the Saccharomycete with this form of growth which has
chiefly come under consideration is yeast, the term Yeast-fungus has usually been
employed instead of Sprouting Fungus ; but this leads to confusion, and the word Yeast-
fungus should not be used for the growth-form, but should be confined to the special
cases to which it is suited.

The Schizomycetes will be described in the third part of this work.

Section II, The cells of the Fungi agree in all important points with the
cells of other plants as regards structure, growth, and mode of division.

The protoplasm, which in most cases fills uninterruptedly the interior of the
young cell, encloses in the full-grown cell of the Fungi, as of other plants, one or

'
6 DIVISION I.—GENERAL MORPHOLOGY.

several sap-cavities (vacuoles), Comparatively large vacuoles are often separated
from one another by thin films-of protoplasm, which in elongated cylindrical cells
are not unfrequently placed across the cell, like transverse septa of cell-membrane,
and this position has before now caused them to be mistaken for transverse cell-
membranes', The greater part of the 86-94 per cent. of water, which Schlossberger
and Döpping found in fleshy mushrooms, is to be placed to the account of the
watery cell-sap.

Errera discovered a remarkably large amount of glycogen in the cells of many
Fungi. This substance permeates the protoplasm, renders it unusually refringent,
and may be recognised under the microscope by this quality and by the charac-
teristic reddish-brown colour which it assumes in the presence of iodine. It occurs
especially in the asci of the Discomycetes and Truffles, but Errera found it also
in the vegetative cells of some of these Fungi, of some of the Mucorini, and of
certain Hymenomycetes, &c.

Nuclei' are found in many cells connected with reproductive processes in. the
Fungi, in asci for example and basidia, and their relations to the formation of daughter-
cells are in some cases at least clearly understood; but there is some uncertainty with
regard to the nuclei in the vegetative cells of the thallus, owing to their minuteness.
On the one hand the presence of nuclei in the vegetative cells is probable where they
have not been directly observed, because the reproductive cells which have nuclei
are formed directly from vegetative cells and are distinguished from them only by
their greater size, which may be the only reason why their nuclei are clearly seen,
and because the nuclein which is characteristic of cell-nuclei has been shown by
macrochemical methods to be present in cells, in which the presence of a morpho-
logical nucleus is not or has not been certainly ascertained. In conformity with this,
Strasburger with the help of colouring reagents detected nuclei in the cells of the thallus
and in the spores of the Saprolegnieae, and Schmitz had previously asserted their
existence in a number of other Fungi, as for instance in Oidium lactis, in the
Peronosporeae, Mucorini, and Saccharomyces; to these may be added Penicil-
lium glaucum (Strasburger) and especially the gonidial state of Peziza Fuckeliana
(Botrytis cinerea). But on the other hand the objects under consideration, except
in the Saprolegnieae, are of such minute size, that the satisfactory discrimination
of true nuclei from other small bodies contained in the protoplasm, and like them
perhaps rendered more distinct by colouring reagents, is extremely difficult, and
can only be obtained after renewed investigations. The accounts in our possession
make it distinctly probable that the protoplasm of the elongated vegetative cells of
the Fungi which have been examined contains several or even many small nuclei,
the division and multiplication of which is not in direct morphological connection
with the vegetative cell-division. Only the short vegetative cells of Saccharomyces
according to Schmitz are uninucleate. The reproductive cells to which we have
referred above have one or more nuclei according to the species; the connection of
the nuclei with the formation of daughter-cells, as far as it is known, will be described
below along with the phenomena of reproduction.

The protoplasm of the cells of the Fungi contain no chlorophyll or analogous

* See Reisseck in Botan. Zeitg. 1853, p. 337.

CHAPTER I,—HISTOLOGICAL CHARACTERISTICS, 7.

colouring matter or amylum-grains, nor, asfar as is known, any vehicles for colouring
matters nor their homologous pdastéds (A. Meyer’s trophoplasts).

It would appear that the formation of fatty matters takes the place very generally
of the amylogenesis which holds in plants containing chlorophyll; these matters
always form a percentage of the dry substance of vegetating Fungi, and may
amount with diminution of the proteid substances to 50 per cent. of the material
stored up in the resting-states, to 35 per cent. in the fatty sclerotia of plants like
Claviceps, and to 50 per cent. in the Moulds (? Penicillium) in the resting or
involution-stage, that is, after the close of vegetation. During the time of active
vegetation the fatty substances are disseminated in the form of minute drops in
the protoplasm of the cells of Fungi, as they are in the cells of other plants, and
help to make it look granular or turbid; in the resting states (periods of involution),
in which reserve-material is stored up, they may collect into large strongly refringent
drops which occupy the largest part of the cell-cavity. Examples of the latter case
are the sclerotia of Claviceps, the thallus of Sphaeria Stigma, Fr., S. discreta, Schw.,
S. eutypa, Fr., Vermicularia minor, old moulds, many spores, &c. &c.

In many cases the collections of fatty matter are colourless or only faintly
coloured, but sometimes they are very highly coloured, if after the analogy of cases
which have been carefully and chemically examined we may venture to apply the
term fatty substance to bodies, of which we only know with certainty that they agree
with fatty aggregates in outward appearance and in the ordinary microchemical
reactions. If the bodies in question are really to be regarded as chemically
definite fats, it still remains to be decided whether the colours belong to the fats
themselves, or are derived from distinct colouring matters which would in that case
be attached to the aggregates of fatty matters as their vehicles. With this reservation
and pending the requisite strict chemical examination, we may designate as coloured
aggregates of fatty substances those microchemically fat-like bodies which produce
the characteristic colouring from yellow to brick-red in so many Fungi—Uredineae,
Tremellineae, Stereum hirsutum, Sphaerobolus, Pilobolus, many Pezizas as P. aurantia,
P. fulgens’, and various other kinds. They are found thinly disseminated ‚in the
protoplasm of actively vegetating and growing cells, imparting to it a uniform
colouring ; after the death of the cells they often run together into larger drops ;
in older cells also they sometimes assume this form spontaneously. In the Uredineae,
and according to Coemans in species of Pilobolus also, the red colouring matter
shows a characteristic reaction, becoming intensely blue when treated with sulphuric
acid, then quickly passing into a dirty green and then gradually losing all colour,
a reaction which is seen in the similar red colouring matter of many parts of plants
which do not belong to the Fungi, and in the red pigment-spots (eye-spots) of
some of the lower forms of animal life. This reaction is not found in the other
Fungi mentioned above. These facts sufficiently point to a different material
composition of the bodies in question in different cases: some of them were
spectroscopically examined by Sorby.

Van Tieghem discovered crysfalloids of albuminoid substance (mucorim) in
the gonidiophores and zygosporophores of most of the Mucorini. J. Klein found

1 P. fulgens, Fr., was named P. cyanoderma in the first edition of this book.

8 DIVISION I.—GENERAL MORPHOLOGY.

them previously in Pilobolus. They have the form of octahedra or truncated
triangular plates, are extruded from the protoplasm as it is preparing to form spores
or sporangia and do not pass into these with the protoplasm; they subsequently
disappear gradually in the decaying sporophore.

Section III. The cell-membrane in the Fungi remains thin and delicate
to the last in most of the quickly-growing short-lived species; in others, especially
in the long-lived solid Mushrooms and Lichens, it is thickened to a variable but
often considerable extent, and is in that case stratified like other membranes.
Formation of pits has been only rarely observed; fibriform, both spiral and annular,
thickenings have been seen only in the capillitium of Batarrea (see Division II).

In their consistence and very limited power of swelling, which has not however
been accurately determined, the membranes of many Fungi are very similar to
the non-gelatinous cellulose-membranes of the higher plants. The elementary
composition of the cellulose has also been ascertained by macrochemical analysis
after proper purification in a number of cases, in Polyporus igniarius, P.
fomentarius, P. officinalis, Agaricus campestris, Daedalea quercina, and Amanita
muscaria. But the colourless, non-gelatinous and. apparently pure cell-membranes of
Fungi of every age are generally distinguished from the typical cellulose-membranes
of the higher plants by being insoluble in ammoniacal solution of cupric hydrate,
and by the absence of their characteristic reactions with iodine; they are not
coloured blue by iodine and sulphuric acid or by Schulze’s solution, or only
after special and prolonged preparation, in the course of which they often display
strong resistance to acids. We may therefore properly distinguish their substance
by the special name of Zungus-cellulose. It remains still undecided whether their
peculiar qualities are due to the presence of foreign deposits in their substance
or to some other causes.

Membranes however are not wanting among the Fungi which display the
typical blue reactions with iodine ; such are all the membranes in the Saprolegnieae,
in Protomyces macrosporus, in the thallus of the Peronosporeae, in the young state
of some species of Mucor (M. Mucedo and M. fusiger), and in the cells of the resting
perithecium of Penicillium glaucum (Brefeld). Clavaria juncea sometimes, but not
always, shows the violet coloration with iodine and sulphuric acid; and this is
the case also with the sterile forms known as Anthina pallida, A. purpurea, and
A. flammea, which probably belong to Clavaria or its allies. Other Clavarieae show
only the Fungus-cellulose. H. Hoffmann’s observations on Amanita phalloides
and Agaricus metatus may also be considered in this connection.

The non-gelatinous membranes of the Fungi, which are always colourless
when young, often become coloured as they grow older, especially in long-lived
forms, assuming usually various shades of brown from the lighter to the very
darkest brown, more rarely some other colour, as the rosy red of the thallus of
the mould, Dactylium macrosporum Fr., the blue of the surface of the thallus
of Peziza fulgens, the green of Peziza aeruginosa, and Phycomyces nitens; the
varied coloration of the membranes of the spores may also be mentioned here.
The colours of the Lichen-fungi will be noticed further on in Division III. Apart
from the Lichens, the colouring matter penetrates uniformly through the whole
of the membrane or through certain lamellae of it.

CHAPTER 1.—HISTOLOGICAL CHARACTERISTICS. 9

The coloration of the membrane is accompanied with increased firmness and in
most cases with exceptional power of resisting the action of concentrated sulphuric
acid, phenomena which taken together recall the similar behaviour of the sclerosed,
lignified, and suberised membranes of the higher plants. With the coloration therefore
we may also speak of the sclerosis of the membranes. We learn also from other
sources that the colouring at least is due to the interposition of substances which
can be withdrawn by solvents from the membrane which then remains behind colour-
less, as we can withdraw the colouring deposits from the sclerosed membranes of
Pteridophytes, or lignin and suberin from lignified and suberised cell-walls. We
cannot at the present day speak of lignification in the strict sense of the word
in connection with the membranes of the Fungi, since they do not show Wiesner’s
reactions when treated with anilin compounds and with phloroglucin. Phenomena
approaching at least to suberisation in the strict sense of the word appear to occur
sometimes, according to C. Richter’s observations on Daedalea quercina. The
greater part of the Fungi have not been subjected to any close examination on these
points ; the purely empirical expressions, coloration and sclerosis, may therefore serve
for the present as general designations of the phenomena.

But there is another kind of membrane in the Fungi which is distinguished from
those hitherto described by its gelahnous or even mucilaginous nature. The mem-
brane in the dry state is hard and cartilaginous and swells by absorption of water to
several times its former volume in the dry state; its consistence therefore in the
moistened vegetating state is that of a tough or soft jelly. The outer layers of many
filamentous mycelia have this gelatinous constitution, which is very conspicuously
seen when the plants are cultivated in a fluid. The hyphae, when examined by
transmitted light, appear to have a delicately thin membrane which seems to be
surrounded by a hyaline fluid; further examination discloses either a distinct
gelatinous sheath round each hypha, or a diffuse gelatinous mass in which the
branched hyphae are all imbedded. Zopf observed this in Fumago for example. The
phenomena present themselves in a very beautiful form in the Sclerotinieae when
cultivated in saccharine solutions. The membranes of Saccharomyces Cerevisiae must
be of this nature according to the observations of Nageli and Léw.

Soft gelatinous membranes also characterise in many cases large masses of tissue
of definite shape, which appear at first sight to be slimy mucilaginous masses and
may be designated gelatinous Issue (Gallertgewebe) or gelatinous felt (Gallertfilz).
Beautiful examples of this formation may be seen among the larger mushrooms in
the gelatinous bodies of the Tremellineae, in the gelatinous layers of the peridium
of the Gasteromycetes, as Geaster hygrometricus, Melanogaster, Hysterangium, the
Phalloideae, Mitremyces, &c. (see Division II), in Bulgaria and Cyttaria, in the greasy
slimy superficial layers of the pileus in such Hymenomycetes as Amanita Muscaria,
Agaricus Mycena of the section Glutinipedes, Boletus luteus, &c., and in the young
mycelial strands of Agaricus melleus (section VII). Membranes of the viscid
gelatinous type are found in the elements of most -Lichen-fungi, in those of the
sclerotia of Sclerotinia and Typhula gyrans (section VIII), of the thallus of Hydnum
erinaceus, of the massive sclerotium-like thallus of Polystigma and of the mycelium
-of Hysterium macrosporum (Hartig). In the three last-named cases and in many
Lichen-fungi (see also Division III) the gelatinous membrane-lamellae are coloured

Io DIVISION I.—GENERAL MORPHOLOGY.

blue directly by a watery solution of iodine. It is a matter of course that there should
be intermediate forms between the highly gelatinous and the non-gelatinous membranes,
such as are found for instance among the sclerotia. To the above-mentioned examples
drawn from the vegetative parts of the thallus must be added the organs of reproduction,
spores and the parts which immediately produce them,—a. not less rich and varied con-
tingent, of which more will be said in the chapters which deal with these organs.

We know very little of the chemical composition of the gelatinous membranes
of the Fungi. From the few tolerably precise investigations and from analyses which
have been made it seems probable that they are for the most part composed of one or
more carbo-hydrates or mixtures of carbo-hydrates nearly allied to cellulose, but with
great capacity for swelling. The membranes of the Lichen-fungi (Cetraria, Ramalina,
Usnea, and Cladonia) are changed by boiling in water into a homogeneous jelly known
as lichenin, the dry substance of which is isomeric with cellulose. According to
Nägeli and Löw the membranes of yeast-cells (Saccharomyces Cerevisiae), after boiling
repeatedly in water, pass partly into a mucilage which they term ‘ yeast-mucilage’ ;
the analysis of its dry substance gave a formula very near 3(C6 Hıo Os)+Hz2 O.
When the membranes of the Lichen-fungi, especially Cetraria islandica, and of the
asci of many of them are coloured blue by the direct action of iodine, the reaction is
due to the carbo-hydrate which is mixed with the lichenin (itself not turning blue '
with iodine) and which can be extracted from it; its formula is also C6 Hıo Os, and
it was named by Dragendorff Zichen-starch!. Most of the gelatinous membranes, like
the yeast-mucilage, do not take the blue colour; they require further examination.

The gelatinous membranes also appear to be in many cases the seats of colouring
matters, for instance of the scarlet-red of the surface of the pileus of Amanita muscaria,
of the yellow of Boletus luteus, and of others, so that we might conclude that the
characteristic colours of the Fungi, with the exception of the reddish-yellow mentioned
above, were in almost all cases confined to the membranes. But to microscopic
examination in the cases named and in some others the colour appears so pale and
so uniformly distributed over the whole cell, that it is difficult to decide with any
certainty whether it belongs to the membranes or to the contents, or whether it is
distributed uniformly through them both.

A review of the anatomy of the membrane leads naturally to the mention of
certain bodies, which are separated out from the cells and are imbedded in or more
usually deposited on the membranes, or are interposed in the interstices of the
hyphal weft; these are resinous excretions, lichen-acids, and especially calcium-
oxalate. The lichen-acids will be noticed again in Division III.

Resinous excretions, the histogenetic relationships of which need not be discussed
in this place, are known in great abundance as a coating of the hyphae which compose
the sporophores of Polyporus officinalis, the mushroom of the Larch, and form
sometimes 79 per cent. of the mass of this plant. Bauke? found the hyphae of a
Diplodia furnished with a brown ‘resin-like‘ covering. Zopf gives a similar account
of species of this genus at page 48 of his work on Chaetomium which will be cited

! Berg, Zur Kenntn. d. Cetraria islandica (Diss. Dorpat. 1872).—Nägeli u. Schwendener, Das
Mikroskop, Aufl. z, 1877, p. 518.
2 Pycniden, p. 35.

CHAPTER I.—HISTOLOGICAL CHARACTERISTICS. 11

later. Both the old mycelium and the walls of the perithecia of Eurotium are marked
by a similar reddish yellow or golden yellow covering.

Calcium oxalate is a substance so generally found in the Fungi that it is quite
unnecessary to enumerate instances of its occurrence. I have noticed its absence in
the Peronosporeae, in many Hyphomycetes, in species of Bovista and Lycoperdon,
and in some Lichens which will be mentioned in Division III, The abundance with
which it occurs on or between the cells of the plant varies according to the species,
the individual, and the age ; it is often more easy to find in young specimens than in
older ones. It not unfrequently appears in the form of regular quadrate octohedra,
but more commonly in that of slender needles, or irregularly shaped nodules, or
angular granules (Figs. 4 and 5). These occur also on reproductive cells, as in the
Mucorineae. When they appear on or in the surface of the plant, they often give it

Fic. 4. Hyphae from the surface of a mycelial strand of FIG. 5. Extremity of a hypha of
Phallus caninus; a bladder-like cells filled with a crystalline the mycelium of Agaricus cam-
sphere of calcium oxalate, 5 small irregular aggregates of the pestrts, covered with small acicular
same salt on the outer surface of the hyphae. Magn. 390 times. crystals of calcium oxalate. Magn.

about 390 times,

a chalky white appearance; this we see in many mycelial strands of Agaricus cam-
pestris, in the Phalloideae, in the thallus of Corticium calcareum and Psoroma
lentigerum. The occurrence of the calcium oxalate inside the cells, though it has
been observed several times, must be regarded as very exceptional. Small rod-like
crystals are occasionally found in the vesicular cells of the stipe and pileus of Russula
adusta. On the narrow cylindrical hyphae of the mycelium of Phallus caninus solitary
large spherical or flask-shaped vesicular cells are found, which are almost filled
by a large glistening sphere of calcium oxalate with a radiating crystalline structure
(Fig. 4).

Structure of the membrane. I wrote at some length in the first edition of this
work on the subject of the structure of the membranes of the vegetative cells of the
Fungi, because it was important at that time to prove its conformity with like parts
in other plants, in opposition to statements, especially of Schacht, founded on the
minuteness of the objects in question, and assuming a much greater general sim-
plicity in them. It will be well to repeat here the matter which was then produced,
with some abbreviations and additions, notwithstanding the fact that it is now twenty
years old, and that modern optical resources have made us acquainted with many
further details in the objects observed ; many fresh examples also might be adduced,
but they are not required,

The young membranes of many woody and leathery Mushrooms, especially the

12 DIVISION I. —GENERAL MORPHOLOGY.

Gastromycetes and Hymenomycetes (Polyporus, Thelephora, &c.), is often compara-
tively thick, and in an older state is not unfrequently much thickened, even to the
obliteration of the lumen. The cells for example of the pileus of Polyporus fomen-
tarius, of Crucibulum vulgare! and many other species, have in some parts the appearance
of solid cylinders, in others have a distinct cavity. The thickened membranes are
either firm and brittle or flexible, or gelatinous and soft. Where the thickening is
slight, as on the lateral walls of many Filamentous Fungi (Dematieae, Botrytis cinerea,
Peronospora), the membrane is usually homogeneous and not stratified, and even
the transverse walls are generally undivisible or with -difficulty divisible into two
lamellae. But strongly thickened walls often show very distinct stratification without
as well as with the aid of reagents which cause swelling of their substance, such
as solution of potash or Schulze’s solution or sulphuric acid. Good examples are the
thallus and gonidiophores of Cystopus, and the cells of the firm rind of the mycelial
strands of Agaricus melleus; to these may be added the thickened membranes which
sometimes occur in Pilobolus in consequence of retarded growth (Coemans). The
membranes of many dry resting Fungus-tissues (Polyporus zonatus, P.” versicolor,
Daedalea, Trametes Pini, Lenzites betulina, the stout hyphae of Thelephora hirsuta,
the threads of the capillitium of Bovista plumbea, Geaster, Tulostoma and many
others) often show at least two distinct layers, an outer and firmer one which is
frequently of a bright colour, and an inner softer and more transparent layer.
Further stratification cannot usually be detected in these cases even with the use
of artificial means such as boiling in potash, though they may be seen sometimes in
an older pileus of Polyporus officinalis. Here may be seen, when the plant is examined
in water, an outer thin and apparently firm layer, and an inner thicker and evidently
soft layer ; the outer layer is not sensibly altered when warmed in a solution of potash,
but the inner swells strongly, so as to protrude like a drop on the surface of fracture
beyond the outer layer, and at the same time often separates into numerous delicate
lamellae.

Very beautiful stratification is also shown in the cells of many Fungi in which the
membrane is gelatinous and is capable of swelling strongly in water. In Geaster
hygrometricus the inner layer of the outer peridium, which bursts in a stellate manner,
consists of straight cell-rows of equal length closely packed together and standing
parallel to one another and perpendicularly to the outer layer; they have a thick
membrane which is hard and cartilaginous in the dry state, but swells in water to
a tough gelatinous consistence and shows in a transverse section three to five lamellae
with different refringent power. The outermost lamellae of the cells in adjoining
rows are pressed close upon one another, and the bounding lines form a clearly
defined network on the transverse section. This structure is often obliterated in
old specimens.

An exactly similar stratification to that which has been described in Geaster is
found in the tissue of Hysterangium clathroides?, which when dry is cartilaginous
but swells and becomes gelatinous in water, and also in the inner substance of many
sclerotia, as in the Sclerotinieae and in Typhula gyrans.

The lower part, the stipe, of the branching body of Calocera viscosa consists of
rows of cells all running nearly parallel to the longitudinal axis of the Fungus. Thin
transverse sections through the stipe give therefore circular or polygonal sections
of the individual cells. The outermost of the three concentric layers of tissue which
compose the stipe is in the fresh state of a viscid gelatinous consistence, and is
fotmed of slender rows of thick-walled cells which appear at first sight to be imbedded
in a soft homogeneous jelly. But if thin cross sections of the dried stipe are allowed
to swell slowly in water, it becomes apparent in this case also that the jelly is formed
of as many gelatinous layers of membrane in close contact with one another at all

1 Sachs in Bot. Ztg. 1855. ? See Tulasne, Fungi hypogaei.

CHAPTER I.—HISTOLOGICAL CHARACTERISTICS. 13

points as there are rows of cells. If the sections are kept for a long time in water,
the delicate bounding lines of the lamellae disappear and the lamellae themselves
coalesce into a homogeneous mass.

The above cases establish the occurrence of lamellae of different thickness and
capacity for swelling in thickened cell-membranes ; but it also follows from the facts
which have been given, that the apparently homogeneous substance between the cells
of these Fungi, like the pseudo-intercellular substance in many Fucoideae, Florideae,
and others, is not to be regarded as a secreted homogeneous substance distinct from
the cell-membrane, but originates in the close contact and partial coalescence of the
outer gelatinous thickening-layers of all the hyphae.

The tissues of many Fungi (Melanogaster, Tremella, Exidia, Guepinia, Dacryomyces,
Bulgaria, Thelephora mesenterica, Mitremyces, Cyttaria, Panus stypticus), the peridia
of the Phalloideae, young Nidularieae, the surface of many Hymenomycetes, as Agaricus
Mycena sect. Glutinipedes, Fr., Amanita muscaria, Boletus luteus, and many others,
are of gelatinous constitution, and agree in structure with those of Calocera, Hysteran-
gium and other forms described above; but the interstitial gelatinous substance
appears in most cases to be really a homogeneous mass, and has not yet been
separated into portions belonging to the individual cells. This may perhaps yet
be done in many of these forms; at the same time it would appear from the
published observations on Calocera and from the close affinity and agreement in
structure between Calocera, Guepinia, and Tremella, and between Hysterangium
and Phallus, &c., that we are justified in considering the homogeneous gelatinous
substance of all the Fungi mentioned above as simply a product of the coalescence
of soft gelatinous thickening-layers of the cell-membranes. H. Hoffmann seems to
take this view}, as he speaks of the gelatinous substance in the outer portions of
the pileus of the fleshy Hymenomycetes as a product of the deliquescence of the
membrane.

The threads of the capillitium in all species, as it would seem, of Lycoperdon
(L. pusillum, L. Bovista, L. giganteum; see Division II) are delicately pitted. The
thick transverse walls of Dactylium macrosporum, Fr. which are formed of two
semi-lenticular lamellae have the large pit in their centre, just in the same way as
it occurs in the transverse walls of filiform Florideae like Callithamnion. I have
never seen similar pits in other Filamentous Fungi ; their transverse walls are usually
delicate, and in some cases, as in Botrytis cinerea, they appear to be thinner in the
centre than at the margin.

Fungus-cellulose. In my first edition I gave the name of Fungus-cellulose to
the substance of the greater part of the non-gelatinous membranes of the Fungi for
the reasons given above. C. Richter has recently arrived at the conclusion that there
is no special modification of cellulose requiring to be distinguished by such a name,
and that the membranes supposed to contain it are composed of ordinary cellulose
with foreign, possibly albuminoid admixtures. He shows that the membranes of
Fungi like Agaricus campestris, Claviceps, Polyporus spec., Daedalea quercina, and
Cladonia, which do not show the characters of ordinary cellulose even when treated
in the customary manner with boiling solution of potash, Schulze’s solution, or chromic
acid, if subjected to longer maceration in a 7-8 per cent. potash solution do give the
ordinary reactions of cellulose, turning blue with iodine and sulphuric acid and with
Schulze’s solution, and being soluble in ammoniacal solution of cupric hydrate. The
maceration must continue for at least 2-3 weeks, sometimes, as in Daedalea, for
as many months. These observations are a welcome confirmation of the near
affinity of the substance of the membranes of the Fungi to ordinary cellulose which was
indicated by macrochemical analysis; but they merely prove that the membrane of
these Fungi is altered by maceration with potash in the way described. Whether

* Icon. analyt. fungorum, pp. 12, 25.

14 DIVISION 1.—GENERAL MORPHOLOGY.

this alteration consists in the removal of some substance which was present from the
first must remain uncertain; such an explanation has not been proved and others
are at least possible. Without going further into the question here, we may merely
recall the fact, that ordinary cellulose is coloured blue by iodine when certain reagents
have produced certain changes in it; but zinc chloride, for instance, does not in this
process remove some admixture which is present in the cellulose and prevents it from
turning blue. Old threads of linen and cotton which have been repeatedly washed
become blue at once in a dilute solution of iodine; the changes in their original
condition which are thus indicated cannot consist in the simple removal of any
substance. From such considerations it appears to me that the cause of the peculiar
character of the Fungus-cellulose is not yet ascertained, and the harmless special
name for it seems still to be desirable.

Coloration. The colouring-matters which are peculiar to the Fungi, i.e. which
are produced in their metabolism, are chiefly if not solely the yellow and the reddish
yellow which are partly attached to the fatty or fat-like contents of the cells, and
partly disseminated through the membranes. It is not therefore too much to say,
that all tints peculiar to the Fungi, which do not belong to the first category, proceed
from the specific colour of the membranes.

An exception to this rule, which may perhaps be regarded as only apparent, is
said to occur in some normally colourless moulds and parasitic forms, which growing
in water on a substratum containing soluble red and violet colouring matters take
up these unaltered in such a manner that even their cell-contents are corre-
spondingly coloured. Fresenius? makes a similar statement with respect ‘to species
of moulds growing among red-coloured Micrococcus prodigiosus, Cohn; I found
the same thing in Eurotium and in species of Mucor growing on red fruits and in
Phytophthora infestans on red and blue potatoes. But I am now doubtful, firstly
whether the colouring of the cell contents is in the protoplasm or in the cell-sap or
in both, and secondly whether it is present in the living Fungus, or appears only
in those of its cells which have been killed in making the preparation and have then
taken up the colouring matter into their protoplasm.

One thing remains to be noticed here which has never yet been explained, the
colouring of Peziza aeruginosa, P. (Chlorosplenium aeruginosum of Tulasne) *.
This Fungus is found on wood with the green rot so common in forests, the colouring
matter of which has been frequently examined since Vauquelin’s time and most re-
cently by Prillieux. The green colouring matter of this wood is usually contained
in its cell-walls, but sometimes forms according to Prillieux in amorphous masses
in the cavities of the wood elements. This is in many cases all that is to be seen;
over wide spaces on and in the wood there is no trace of a coloured or uncoloured
Fungus to be seen; (Gümbel, Fordos, and myself). Ifa Peziza occurs on and in wood
of this kind, almost all parts of it are coloured green, and the colour is in the mem-
branes and perhaps also in the interior of the cells of the Fungus, and often in
such quantity that the Fungus is more deeply coloured than the wood itself. Single
fructifications of the Peziza however rising from the wood are sometimes uncoloured,
a pure white, in their upper parts which are farthest from the surface of the wood.
These facts taken together led to the view that the green colouring matter is a
product of the decomposition of the wood without the co-operation of the Peziza,
which takes it up unaltered when it settles in the wood. The fact that Peziza
aeruginosa only grows, as far as is known, on this green-rotting wood, and on no
other substance, is not in itself a valid objection to this view. But there are on the
other hand so many established instances of specific decompositions effected by
certain Fungi, that the repeated confirmation of the above-mentioned fact and the
absence of other species of Fungus were constantly suggesting the idea that the

! Beitr. 80. 2 Carpol. III, p. 188.

CHAPTER I. —HISTOLOGICAL CHARACTERISTICS, 15

green colour of the decaying wood must be a consequence, and the colouring matter
a product of the Peziza which grows in and upon it. The question is still undecided ;
but I have myself recently observed the important fact, that green-rotted wood is
sometimes found in which microscopic examination can discover no evident colora-
tion of the wood elements, bat shows the presence inside them of numerous in-
tensely green hyphae which most certainly belong to Peziza aeruginosa. All our
observations show that the Fungus wherever it occurs always contains the green
colouring matter ; it occurs only in green-rotting wood, and the view that the wood
owes its colour to the Fungus must be allowed to be probable. The fact that wood
is found with this particular form of decay but unquestionably free from the Fungus
appears to be quite irreconcilable with this view; but the objection disappears if
we suppose with Cornu that the hyphae of the Peziza which vegetate in the wood are
short-lived, and convey all their colouring matter to the wood when they die. It
ought not to be difficult to settle this question by artificial cultivation.

One striking case of coloration may be added here, though strictly speaking it does
not belong to our present subject. The tissue of the pileus of certain Boleti, especially
Boletus luridus which in the uninjured state is yellow, assumes a blue colour as
soon as it comes into contact with the outer air. Schönbein has carefully examined
this phenomenon, and finds that it is a substance capable of being extracted from the
Fungus by alcohol and probably of a resinous character which turns blue in the
air, The blue colour appears in the alcoholic solution under the same conditions
as it does in a solution of guaiac-resin, and since it has been proved that the
colour is produced in the latter by combination with ozonised oxygen, Schönbein
assumes a similar cause of the blue colour in the Fungus. The alcoholic extract
from the Boletus does not by itself become blue when exposed to the air; there
must therefore be another substance contained in the Fungus, which ozonises
the oxygen of the atmosphere, and then effects a combination with the resin,
giving off the oxygen to it in the state of ozone. Phenomena of a similar kind
observed in other cases confirm this conjecture. Thus both the tincture of guaiac
and the alcoholic extract of Boletus turn blue at once, if they are allowed to fall in
drops on the fresh tissue of some of the Agarici which do not themselves turn blue,
especially Agaricus sanguineus. The watery juice of Agaricus sanguineus squeezed
out from the plant and filtered produces the blue colour at once in both tinctures.
From these facts it may be concluded that a number of fleshy Fungi contain a
substance soluble in water, which absorbs oxygen and gives it up to other bodies
in the state of ozone. The Boleti which turn blue contain this substance with
another resinous substance, which like guaiac-resin is turned blue by ozone.

Literature of sections II and III :—

1. Cell-structure of the Fungi; structure and chemical composition of the cell-
walls. ,

SCHACHT, Die Pflanzenzelle, p. 136 ;—Id. Lehrbuch d. Anat. d. Pf.

COEMANS, Monogr. du genre Pilobolus in Mém. des savants &trang. Acad. Bruxelles,
XXX.

CASPARY, Monatsber. d. Berliner Acad. Mai, 1855.

H. HOFFMANN in Bot. Ztg. 1856, p. 158.

H. v. MOHL in Bot. Ztg. 1854, p. 771.

DE Bary, Unters. über d. Brandpilze ;—Id. Ueber Anthina in Hedwigia, I. 36 ;—
Id. in Bot. Ztg. 1854, p. 466.

BRACCONOT in Ann. de Chimie, XII. 172.

PAYEN, Mémoire sur le développement des végétaux in Mémoires présentés A l’Acad.
des sc. de France, IX (1846), p. 21.

MULDER, Physiol. Chemie, Braunschw. 1844-51, pp. 202, 203, where Fromberg’s
results are also given,

16

DIVISION I.—GENERAL MORPHOLOGY.

SCHLOSSBERGER, Ueber d. Natur d. Hefe (Ann. d. Chem. u. Pharm. 51, p. 206).

SCHLOSSBERGER u. DOPPING, Beitr. z. Kenntn. d. Schwämme (Ann. d. Chem. u.
Pharm. 52, p. 116.

A. KAISER, Chem. Unters. d. Agaricus muscarius L. (Inaugural-Diss., Göttingen,
1862).

BURGERSTEIN in Sitzungsber. d. Wiener Acad. 70.

C. RICHTER in Sitzgsber. d. Wien. Acad. 83, p. 494.

NÄGELI u. Löw, Ueber d. chem. Zusammensetzung d. Hefe (Sitzungsber. d. Bayr.
Acad. zu München, Mai 4, 1878).

NÄGELI u. SCHWENDENER, Das Mikroskop, Aufl. 2, p. 518.

FÜISTING in Bot. Ztg. 1868, p. 660.

See also the literature of the Lichens in Division III.

2. Cell-nucleus, cell-division.

SCHIMTZ, F., Ueber d. Zellkerne d. Thallophyten (Sitzgsber. d. Niederrh. Ges. Aug.
4, 1879).

ZACHARIAS, Ueber d. Beziehung d. Nucleus, &c. (Bot. Ztg. 1881, p. 169), where other
literature is noticed.

STRASBURGER, Zellbildung u. Zelltheilung, Aufl. 3, 1880, p. 221, Taf. XIV.

3. Glycogen.

ERRERA, L., L’épiplasme des Ascomycétes et le glycogéne des vegetaux (Thése,
Bruxelles, 1882);—Id. Sur le glycogéne des Mucorinées (Bull. de l’Acad. de
Bruxelles, Nov. 1882).

4. Cell-contents, fat, crystalloids.

NAGELI, Ueber d. Fettbildung bei d. niederen Pilzen (Sitzgsber. d. Bayr. Acad.
München, 1879, p. 237).

ROSTAFINSKI in Bot. Ztg. 1881, p. 461.

SORBY, On comparative vegetable Chromatology (Proc. Roy. Soc. London, XXI,
P. 442). See also Just’s Jahresber. 1873.

VAN TIEGHEM, Nouvelles recherches sur les Mucorinées (Ann. d. sc. nat., Ser. 6, I,
P- 24). See also the literature at the end of sect. XLIV.

5. Resinous secretions.
HARZ in Bull. Soc. Imp. de Moscou, 1868.

6. Green rot in wood.
VAUQUELIN in Ann. du Mus. d’hist. nat. VII, p. 167 (1866).
GUMBEL in Flora, 1858, p. 113.
BLEY in Arch. d. Pharmac. 1858.
FORDOS in Comptes rend. Acad. d. sc. Paris, 87, p. 50 (1863).
ROMMIER in Comptes rend. Acad. d. sc. Paris, 66, p. 108 (1868).
PRILLIEUX in Bull. Soc. Bot. de France, 1877, p. 167.
CORNU in Bull. Soc. Bot. de France, 1877, p. 174.

7. Boleti which turn blue.

SCHÖNBEIN in Verhandl. d. naturf. Ges. Basel, 3 (1856), p. 339 ;—Id. in Abhandl. d.
K. Bayer. Acad. VII (1855), and in Bot. Ztg. 1856, p. 819 ;—Id. in Bull. de
l’Acad. de Belgique, Ser. 2, VIII, pp. 365, 372, and in Comptes rend. Jul. 16,
1860.

CHAPTER 11.—DIFFERENTIATION OF THE THALLUS. 17

It does not fall within the scope of this work to go into the details of chemical
analysis ; the reader is referred for these to—

Husemanx und Hırcer, Die Pflanzenreiche, Aufl. 2. See also the first edition
of A. and Th. Husemann.

Frückıger, Pharmacognosie d. Pflanzenreichs, Aufl. 2, Berlin, 1883. The work
contains exact accounts of Claviceps, Polyporus officinalis, Cetraria, &c.

G. DRAGENDORFF, Die qualitative u. quantitative Analyse von Pflanzen u.
Pflanzentheilen, Göttingen, 1882.

J. Könıe, Chemische Zusammensetzung d. menschlichen Nahrungs- u. Genuss-
mittel, Berlin, 1878 (Edible mushrooms).

CHAPTER II. DIFFERENTIATION OF THE THALLUS.

1. GENERAL SURVEY.

Section IV. The thallus of the greater part of the Fungi which are composed of
hyphae is differentiated into two chief parts, a vegetative part known by the name of
mycelium since the time of Trattinick', and the sporophore? (Fruchtträger, receptaculum
of Leveillé, encarpium of Trattinick), which bears and produces the organs of repro-
duction and springs often in great numbers from the mycelium. It need scarcely be said
that there are many gradations in the sharpness of this differentiation. The views and
the terminology drawn from the species in which the differentiation is sharply defined
have often been transferred to those in which it is less distinct. In simple
filamentous forms, as Protomyces for instance and Entyloma, in which the repro-
ductive cells are formed directly as segments of hyphae which are not further
differentiated, we speak of these cells being formed directly on the mycelium. In
many cases this distinction between mycelium and sporophore may be said to be
only arbitrary.

Owing to the peculiar mode of life of the Lichen-fungi, the differentiation in
many of them is to some extent different from that of the rest of the Fungi,
and the traditional terminology therefore, which will be considered in Division III,
is also different.

The mycelium is that part of the thallus which spreads in or on the substratum,
derives nourishment from it and attaches the Fungus to it. In accordance with these
functions it resembles the root-bearing rhizomes of the higher plants, and still more
the rhizoids of Mosses in various points of form and growth. The sporophores may
be compared to the flowering or fruit-bearing shoots of higher plants in respect of
their function to which their form corresponds, and which consists essentially in the
formation of organs of reproduction.

1 Fungi austriaci, 1805.
? See note at beginning of section X regarding the use of the term sporophore.

[4] c

18 DIVISION I.—GENERAL MORPHOLOGY.

2. THE MYCELIUM.

Section V. The mycelia in their original form are always free hyphae; they
either retain this character during their whole life, or the hyphae as they grow
become at most loosely interwoven with one another without forming bodies with a
definite shape and outline, filamentous or floccose mycelia; or the hyphae form by
their union elongated branching strands (fibrous or fibrillose mycelia), or membranous
expansions, or tuber-like bodies, sclerotza.

The filamentous mycelia are much the most common, and in the majority of
Fungi they are the only known form. Their character has been already described in
speaking in the first chapter of the hyphae of the Fungi generally. The branching of
the mycelial filaments in all cases that have been observed with certainty is mono-
podial. The phenomena of coalescence of hyphal cells that were originally free, and
of clamp-connections which were described above, appear as a rule in their most
striking form in filamentous mycelia.

Differences in the structure of mycelial filaments must necessarily depend
chiefly on the presence or absence of a regular system of transverse walls, and this, as
has been already intimated, varies in the different groups. (See also Chapter V.) Every
species in each of the two chief categories thus obtained exhibits as a rule its own
peculiar phenomena of growth and differentiation, provided the normal conditions of
growth remain unchanged, and by these phenomena the several species and groups of
species can be distinguished from one another. These differences relate to the
average size and special form of the cells, the divergence of the branches, the phenomena
of coalescence and the like. Owing to the diminutive size of the objects, they are
usually very inconspicuous even under the most favourable conditions of growth,
and to ascertain them with certainty requires careful observation. They are liable also
to so many changes from external causes that the determination of a mycelium, which
under favourable conditions of development has well-marked characters, without its
sporophore may be attended with considerable difficulty in practice, if it has to be
observed under less favourable circumstances. Much advance has been made in this
point of late years through the careful examination of individual species, so that we
may expect that the morphological characters of the mycelia of many species
and groups of species will in time be clearly determined.

Some filamentous mycelia, belonging to species from very distinct groups, are
distinguished by having special organs of attachment and suction, known as haustoria;
these are peculiar branches which attach the mycelium firmly to the substratum,
and in most cases also evidently serve to take up nutriment from it. Such organs are
found in many, but by no means in all, parasitic species living on plants and
belonging to very different groups, as the Peronosporeae, Piptocephalis, the
Uredineae, and Erysipheae.

The mycelial filaments of these Fungi spread themselves on or among the cells
of the host ; the haustoria are formed on them as special lateral branches which force

“their way into the interior of the cells; they vary in form according to the species and
are more or less, often extremely, unlike the extracellular hyphae. Organs of attach-
ment, which at least very nearly resemble the haustoria of these parasites, are found
in a few other non-parasitic mycelia; they will be noticed again subsequently.

CHAP, II.—DIFFERENTIATION OF THE THALLUS.—-FILAMENTOUS MYCELIA. 19

Careful investigations into the formation of the mycelia of distinct species of non-
parasitic Fungi are to be found especially in Brefeld’s Untersuchungen iiber Schim-
melpilze.

The formation of clamp-connections described above may be taken as an example
of a peculiarity which is characteristic of the larger groups. It occurs, as far as we at
present know, almost exclusively in the Basidiomycetes and chiefly in the Agaricineae ;
it is found in the Tuberaceae, but apparently in no other Ascomycetes. Its occurrence
in Peziza Sclerotiorum, as stated in my first edition, seems not to be confirmed in more

FıG.6. a and 5 Podosphi Castagnei, Lev. a epid I cells of Melampyrum sj 2 ;a branched ial hypha
is creeping over the surface and has sent a haustorium into one of the cells (surface view). 5 vertical section through
epidermal cells with mycelial hypha and a haustorium which has penetrated into a cell. ca spore (gonidium) of Erysiphe
Umbelliferarum putting forth germ-tubes on the epidermis of Anthriscus sylvestris. The smaller germ-tube on the right
is sending a haustorium from the lobed disk into an epid cell. a and 4 magn. 600, ¢ 375 times.

recent times. It is at present uncertain whether it is a feature of all the Basidiomycetes
or only of all the Agaricineae, and the more so as according to Brefeld it is frequent
in one species of the genus Coprinus, but comparatively rare in all the rest.

A greater number of distinctly marked characters
have been observed in the mycelia of parasitic Fungi,
especially the Erysipheae, Peronosporeae, Uredineae,
and Ustilagineae than in other forms, and they have
been observed for a longer time. Such characters
occur chiefly in the formation of the haustoria of
many species and groups of species in those divisions ;
the following are examples of them.

The mycelial filaments of the Erysipheae (Figs.
6, 7) are furnished with transverse walls, and their
numerous but distant branches spread themselves over
the epidermis of phanerogamous plants, being generally
closely applied to it, but at the same time easily pic, 5. Erysiphe (Oidium) Tuckert. My
separable from it. At certain circumscribed spots, how- celial hypha with lobed attachment-disk on
ever, they are firmly attached to the substratum, and 7g. un Tab. XN. "Mage rn man (Bol.
in these spots they are provided with a haustorium
which, springing as a branch from a cell of the mycelium in the form of a very
delicate tube, pierces the outer wall of the nearest cell of the epidermis and enters
its cavity; there it enlarges into an ellipsoid or somewhat elongated persisting vesicle
filled with protoplasm, which in Erysiphe graminis is branched in a peculiar manner. The

Cc 2

20 DIVISION I. —GENERAL MORPHOLOGY.

mycelial filament according to the species is either not altered at all at the point of
origin of a haustorium, or is at most only slightly enlarged there ; or it has a flat nearly
semicircular protuberance the height of which is at most equal to its own diameter ; or
it has a protuberance in the form of a bluntly lobed disk scarcely exceeding the breadth
of the filament, which is pressed closely down on the epidermis, and appears on both
sides or only on one side beyond the flank of the filament. These lobed attachment-
disks were first discovered by Zanardini in-Erysiphe Tuckeri.

The thick mycelial tubes of the Peronosporeae, which are usually without
transverse walls and spread among the cells inside living plants, often clinging close
to the outer surface of their walls, send haustoria into the cells, which have very
different forms in the different species. In Cystopus (Fig. 8 A), Peronospora nivea,
P. pygmaea, P. densa and others,
they are like those ofthe Erysipheae
but much smaller, and they usually
or perhaps in all cases only make
a deep indentation in the walls of
the cells; in P. parasitica they are
lobately branched tubes, and their
vesicular club-shaped branches often
quite fill the cells of the host; in
most of the pleuroblastic Perono-
sporeae (Fig. 8 3) they are slender
filiform lateral branches of the in-
tercellular filaments with many
curved and winding ramifications
in the interior of the cells. In Phy-
tophthora infestans, which inhabits
the potato, branches of the myce-
lium which in this case scarcely

Fic. 8. Mycelial tubes 7 creeping about in the intercellular spaces with deserve a separate name force their

their haustoria penetrating into the cells z—z; A of Cystopus candidus, = . .
from the pith of Lepidium sativum, B of Peronospora catotheca from the way at varlous spots, especially ın

pith of 4sPerula odorata. Magn. 390 times. the sprouting tubers, into the cells
of the host.

The intercellular mycelium of the Uredineae has a variety of haustoria formed like
those of the Peronosporeae, especially the pleuroblastic species, and with them should be
mentioned also the winding intracellular mycelial branches of the Ustilagineae.

The haustoria of Piptocephalis, Syncephalis, and Mortierella are very different
from those which we have hitherto been considering. Piptocephalis Freseniana is
parasitic on the larger Mucorini, and its mycelium, like that of its hosts, con-
sists of tubes without transverse walls. If a growing filament of the mycelium
of the parasite comes in contact with a mucor-tube, either with its apex or with
its lateral wall, it spreads out slightly at the point of contact and thus attaches itself
firmly as with a cupping-glass to the Mucor. A tuft of filiform radiating branching
processes of such extreme delicacy that nothing is known of their minute structure
now shoot forth from the middle of the surface of attachment into the cell of the host.
The length of these suction-filaments is about equal to the diameter of the mucor-tube
(see section XLIII). Van Tieghem and Le Monnier describe similar arrangements
in Mortierella and Syncephalis, only in these genera the tubes which enter the cells of
the host are not so different from those of the rest of the mycelium.

An allied case, though with important points of difference, is that of the clusters of
haustoria in Chaetocladium Jonesii, a form which is usually parasitic on species
of Mucor like the genera just described, and resembles them in structure. The tubes
of this Fungus, both of its mycelium which spreads in the substratum and of the part’ of
its thallus which rises above it, become firmly attached at the point of contact to the

CHAPTER II.—DIFFERENTIATION OF THE THALLUS.—MYCELIAL LAYERS. 21

mucor-tubes which they encounter, and enter into open communication with them at
this point by the dissolution of the cell-membranes and complete coalescence of the
protoplasm of both plants. At these points of union they now put out small vesicular
projections, which in strong specimens appear in numbers close together and form clusters
which may reach the size of a pin’s head. It is obvious that these vesicles do not, like
the haustoria in the previous cases, serve as organs of attachment and nutrition, for
organs of the kind are rendered unnecessary by the-union of the parasite and the host.
They are evidently storehouses of food-material, and the fertile branches of the thallus
spring chiefly from them. But in relation to the morphological points at present under
consideration they are in their nature essentially branches of the mycelium, which
however stand in the closest and most exclusive relation to the physiological function
above mentioned.

Organs of attachment of an unusual kind resembling haustoria are peculiar to the
species of Sclerotinia which have been examined, S. tuberosa, S. Sclerotiorum,
S. ciborioides, S. Fuckeliana, and also to the gonidial state of this species known
as Botrytis cinerea. Under conditions to be described in the sequel the mycelium
of these plants, often when still quite young, forms short branches on which arise
tufts of secondary branches, which becoming closely clustered together are divided

“ by numerous transverse walls into short segments with membranes that become dark
brown with time. The clusters may be of the size of a pin’s head, and have then
been mistaken for sclerotia, with which however they have no connection. They
are formed when the mycelium under conditions of plenteous nourishment is‘ growing
on a solid substratum, such as a plate of glass, which it cannot penetrate, and they
apply themselves closely to the substratum. On substances into which the plant
penetrates, such as the parts of plants which are suited to it, the tufts are not formed
at all or are only feebly developed, in which case their branches soon pass into the
substance of the host and grow there into slender branches of the mycelium. Brefeld
gives figures of these formations in his Schimmelpilze'.

Section VI. The mycelial hyphae of many Fungi, when the conditions are
favourable, become interwoven with one another and form membranous layers
which may be of considerable extent and thickness.

This is the case with such Hyphomycetes as Aspergillus niger, A. clavatus, and
Penicillium glaucum, which in their simpler condition have a filamentous and floccose
mycelium, if they grow on the surface of a moist nutritive substratum. They some-
times form large expansions on the surface of fluids, and may be lifted off them like
a cloth. The free surface of the mycelium is in these cases usually clothed with the
filiform sporophores.

A second series of examples is supplied by many, perhaps by the larger part, of
the solid and especially of the woody and wood-inhabiting Hymenomycetes, the
mycelia of which form very thick membranes or crusts, sometimes of considerable
breadth and some millimetres in thickness, on the free surface of the substratum or in
clefts inside carious stems of trees. Sporophores spring on the one side directly
from the membranes, and on the other single filaments or bundles of filaments branch
off from them and penetrate into the substratum. Other instances occur here and
there in other groups, and are mentioned in special publications?.

Apart from the exceptional case of Agaricus melleus which will be described
below, the only general remark of importance upon the structure of these mycelial

1 Schimmelpilze, IV, t. IX.
* See the literature cited at the end of the chapter.

22 DIVISION I.—GENERAL MORPHOLOGY.

membranes, which our present knowledge enables us to add to what has been already
said, is that they only occur in Fungi with septate hyphae; the structure of the
mycelium varies of course in particular points in each species.

Special generic and specific names have in former times been repeatedly given
to mycelial membranes which are only known in the sterile state. Persoon’s genus
Mycoderma! may be composed to a great extent of forms of this kind which belong
to the Hyphomycetes or to the Ascomycetes. Racodium cellare of Persoon? which
forms the well-known olive-brown coating on old casks in cellars is, as far as we
know, a mycelium formed of loosely interwoven filaments, the origin and reproductive
organs of which are still quite unknown.

The mycelial membranes named by Tode and Persoon Athelia and Xylostroma
are of a firmer kind. The Athelieae are the sterile states of the Thelephoreae
(Thelephora, Hypochnus), in part perhaps their undeveloped sporophores ; the Xylo-
stromeae, which occur as broad flat formations of a woody or leathery texture in the
decaying stems of trees, are the like states of firm wood-destroying Hymenomycetes,
such as Polyporus abietinus, Thelephora hirsuta, Th. crocea, Schrad., Th. setigera,
Fr., Th. suaveolens, Trametes Pini, Daedalea quercina, and other species of these and
allied genera. -

Section VII. The hyphae of the mycelia of many Fungi unite together into
strands, which in their form, branching, and mode of spreading in the substratum
look to the unassisted eye more or less like the roots of higher plants. Even
some species of Hyphomycetes, those for instance known as Acrostalagmus, show
a tendency to this kind of formation. But it is most frequent among the Fungi
which have compound sporophores, such as the Phalloideae, many Lycoperdaceae,
the Hymenogastreae, Nidularieae, and Sphaerobolus, in many of the Agaricineae,
as A. campestris, A. praecox, A. dryophilus, A. aeruginosus, A. metatus, A. andro-
saceus, A. Rotula, A. platyphyllus and A. melleus, and amongst Ascomycetes, such
as Elaphomyces, some species of Genea, Peziza Rapulum, Bull., and P. fulgens;
the endophytic mycelium of Polystigma stellare, Lk., may. be added to the list. It is
evident from these examples that the formation of strands is not necessarily found in
all the species that belong to the cycles of affinity indicated by the above names; on
the contrary it may be wanting in one of two nearly allied species and be found in the
other.

The strands, as has been said, spread themselves out in and on the substratum,
growing at the apex and putting out similar branches, the arrangement of which
scarcely follows any exact rule even in the same species. In each case the strands
may either be in part free and tapering, or they may in part unite to form a coarser
or finer net-work, or they may in part lose themselves in a loose filamentous web, or
a single strand or several combined may expand into membranes, which spread
over the substratum or spin ‘themselves round bodies contained in it. Fresh
strands may then take their rise from these expansions. This variation of form is
essentially dependent on the character of the environment and its influence on
the nutriticn of the Fungus, as is well shown in the case of Agaricus melleus to be
hereafter described.

In most cases which have been examined the strands are composed of uniform

1 Mycol. Europ. p. 96. * Syn. Fungor. 701.

CHAPTER II.-—DIFFERENTIATION OF THE THALLUS.—MYCELIAL STRANDS, 23

hyphae with transverse septation, which vary according to the species. They generally
run parallel to the longitudinal axis of the strands and are straight or undulating, and
are either grown together by their lateral walls, as in Polystigma stellare, Agaricus
Rotula and A. metatus, &c., or they are loosely woven together, as in Elaphomyces,
the Nidularieae, Scleroderma, and the Hymenogastreae.

The structure of such Phalloideae as have been examined, of the Lycoperdaceae
and of some Agarici, is somewhat more complicated. The strands of Phallus
impudicus creep in the ground and may be several feet in length and 2 mm. in
thickness. A transverse section through the stronger branches shows a thin, firm,
white, outer layer or rind enclosing a thick cylinder of a brownish colour and
gelatinous appearance (the medulla). The central and larger portion of the
medullary substance consists of a felt of tough gelatinous character, in which the
hyphae run longitudinally and are slightly sinuous and of unequal thickness. The
outer portion of the medullary substance is exclusively formed of thicker hyphae.
The rind is composed of a few layers of broad thin-walled hyphae wound firmly round
the medullary cylinder in narrow spiral coils. It is easy to see that these hyphae
spring as branches from the peripheral elements of the medullary tissue, then curve
outwards and join the tissue of the rind. They form on their surface short distant
branchlets which make the strands appear as if clothed with short hairs. The entire
surface of the strands is covered with calcium-oxalate.

The strands of Agaricus platyphyllus’ are very like the above in thickness,
appearance, and structure, only the hyphae all run in the longitudinal direction and
their walls are on the whole of firmer texture.

The strands of Phallus caninus resemble likewise those of Ph. impudicus, but
are smaller in every respect. Here too all the hyphae run parallel to one another in the
stouter parts which may be ı mm. in thickness, and the white rind is distinguished
from the yellowish gelatinous medullary substance which contains no air by more
loosely interwoven hyphae, by air-filled interstices, and by the copious deposit of
calcium-oxalate on the hyphae and in the vesicular cells described on page 11.
Clathrus shows similar characters as far as my observation has gone. The rind and
the medulla are often less distinctly separated from one another in the more slender
branches of higher orders, but the former is always distinguished by its covering of
calcium-oxalate. The strands of the Agarici (Agaricus campestris, A. aeruginosus,
and A. praecox) and those of the Lycoperdaceae have the appearance of the
slenderer branches of Phallus caninus and the same structure in all important points.
The presence of the calcium-oxalate varies according to the genera and species, as
was stated on page II.

The formation of strands reaches its highest development, as far as is at present
known, in the mycelium of Agaricus melleus. An excellent description ofthe structure
and growth of this plant by Jos. Schmitz was published, with some additions by
myself, in the first edition of this work ; its life-history was elucidated by R. Hartig,
and our knowledge of it was subsequently completed by Brefeld’s cultures.. There is
the more reason for giving an account of the results of these investigations in this
place because Agaricus melleus is the only one of the forms which we are at present
considering in which the course of development has been followed from beginning to

! See Fries, Icones sel. Hymenomycetum, I, t. 61.

24

DIVISION I.—GENERAL MORPHOLOGY.

end. Agaricus melleus is chiefly a parasite on living European Abietineae (see

Division II).

It makes its way into the roots or the base of the stem beneath the

ground, and the mycelium spreads in the cambium zone and in the young bast, forming

M

U:
ji

N
FIG. 10. Agaricus
of the growing apex oO:

f

FIG.9. Agaricus melleus. Me-
dian longitudinal section through
the growing apex of a
nean mycelial strand, seen by trans.
mitted light. Magn. 40 times.

THE
ne
Hl

es f

Y
un
AN N a
it

cil we
\ hen
a J
\\ x
N Ihn

NN Ph,
nL
a TRO N hs hi

N
N

melleus. Thin median longitudinal section through the extremity

f a subterranean mycelial strand, Magn. 250 times, but the Srawing

d under higher magnifying power.

compressed or membrane-like expanded networks of strands at the cost of the sap-

containing layers of tissue, and also sends

T

FIG. 11. Agaricus dee section
young branch of a subterranean mycelial strand in about the
lower half of Fig. 9. «the axile large-celled tissue passing
the outside into the later-formed rind. The outer limit of the
rind is at 4; outside 5 is the covering of gelatinous felt with
ding hair-like b hes A. Magn. 190 times.

out a large number of single hyphae from
these strands into the rind and wood, and
especially into the medullary rays, where
they spread widely. From these zni/ra-
matrical, especially subcortical, parts other
strands may proceed which develope as
extramatrical strands usually in the soil,
and are therefore sué/erranean, and branch
and spread the Furigus over wide distances
from one tree to another. These strands
become more than 3 mm. thick and are
round on the transverse section; they can
also develope into enormous masses in
moist rotting timber.

The cylindrical subterranean strands
consist when fully formed of a dark-brown,
brittle, usually smooth peripheral tissue or
rind enclosing a white finely-felted me-
dulla. The rind, which in stout specimens
has the thickness of paper, is formed in

its outer portion of about twelve or more layers of cell-rows (hyphae) running down the
length of the strand, and connected with one another laterally without interspaces,

CHAPTER II.—DIFFERENTIATION OF THE THALLUS.—-MYCELIAL STRANDS. 25

The cells of the hyphae are 2-4 times longer than broad, and have a firm brown
membrane and a polygonal transverse section in conformity with the absence of
intercellular spaces; the cells of the outer layers are narrower than those of the inner
and have much thicker walls. The stratification of their membranes becomes more
conspicuous when they are treated with potash.

The medulla consists chiefly of slender tough longitudinal hyphae about 1.5 mm.
in thickness, which form acute angles with one another as they interweave, and have
air in their interstices. Their membranes are comparatively firm; septation and
branching are rarely seen in full-grown specimens. The slender medullary hyphae
are in connection with the innermost layers of the rind; longitudinal sections show
them arising as numerous branches from the cells of these layers, and making their
way between them or running directly from them in oblique or transverse course to
the medullary tissue. The longitudinal arrangement of the layers bordering on the
medulla is thus rendered irregular to a degree which varies in each specimen and is
sometimes considerable. .

I have observed the development of the subterranean strands on adventitious
branches, which it is not difficult to obtain from old specimens if cultivated in a damp
chamber. The apex ofsuch a branch, as it rapidly elongates (Figs. 9 and ro), is conical
in form and colourless for a distance of some millimetres. It consists of a weft of
delicate hyphae rich in protoplasm, the terminal branches of which form at the apex a
loosely tangled tuft rendered slimy by the gelatinous swelling of the membranes.
The apical tissue is continued downwards in the periphery of the branch into the
gelatinous felt which covers it and which will be described presently, and in the
middle into a short-celled irregular tissue of interwoven hyphae without interspaces,
which forms the real conical growing point of the body of the strand. Active
meristematic cell-multiplication, which cannot be followed in detail on account of the _
close interweaving of the hyphae, takes place in the uppermost region ; close beneath
this, where the strand begins to grow broader, there is partly elongation and extension
of the elements of the tissue, partly formation of new elements. The former affects
first and chiefly the axile portion of the strand, which occupies a third part of the
total thickness; its cells subsequently undergo a few divisions close beneath the
growing point and expand rapidly to a breadth of about 12-20 p» and 2-8 times that
length ; they continue thin-walled, are filled chiefly with hyaline cell-sap and are
arranged in straight longitudinal rows. They diminish gradually in breadth as they
approach the peripheral tissue (compare Figs. ro and 11). An evident elongation
of the cells takes place in the peripheral tissue, which serves to show more clearly their
arrangement in longitudinal rows, but the increase in breadth is only small. As the
circumference of the strand increases with every successive transverse section from
the apex of the cone to the fully formed cylinder, and the hyphae are in close contact
with one another without interstices, there must necessarily be an interpolation of new
hyphal branches between those already formed.

The development of the definitive structure of the strand begins with the passage
into the ultimate cylindrical form. The increase in the breadth of the large axile cells
ceases near the apex, where the peripheral layers of the circumference ‘increase con-
siderably ; the consequence is that the axile cells are torn from one another especially
laterally, and intercellular spaces are formed between them, which serve from the first

26 DIVISION I.—GENERAL MORPHOLOGY.

to conduct air (Fig.10). The spaces widen most in the centre of the axile strand ; in
the simplest case a single large axile cavity is formed, and narrow air-spaces join on
to it on the side of the periphery; in other cases single rows of cells remain in the
centre of the cavity separated for the most part from the adjacent tissue and therefore
quickly drying up; here too therefore there is really an air-filled axile cavity ; its
diameter varies much, but it is always at least half as large as that of the strand, and
in strong specimens may reach a much larger relative size.

The wall which encloses the cavity consists in its immediate vicinity of the
original large axile cells; these form about six irregular layers round the cavity, the
cells of the outer layers becoming gradually narrower, as was stated above, and it is
these layers which give rise to the medulla of the fully formed strand in the way which
will be described presently. Outside of the zone which produces the medulla are the
numerous layers of the close compact tissue, which ultimately forms the rind of the
strand. This tissue does not however extend to the surface ; this is occupied by a
supplementary stratum of about six layers of hyphae with narrow lumina and thick
gelatinous walls, which have coalesced into homogeneous mucilage, the gelatinous
felt mentioned above. The hyphae of this tissue run for the most part longitudinally,
and join with the hyphae of the apical tuft. They also give off spreading branches
from the surface. From these must be distinguished other spreading branches, also
provided with gelatinous walls, which spring from the hyphae of the rind beneath the
gelatinous felt, and pass transversely through it towards the outside. Their number
and distinction vary in individual specimens, and according to Hartig they are of special
importance when the Fungus finds opportunity for adopting a parasitic life. A sharply
defined boundary line between the innermost elements of the gelatinous felted layer
and the outermost of the later rind cannot be drawn in the earlier stages of
development.

The assumption by the tissue of its ultimate form begins with the thickening
and turning brown of the walls of the hyphae. It advances on the transverse
section from without inwards, and its first beginnings may be followed upwards
to the base of the young apical cone. As the coloration advances the gelatinous
felt which covers the rind dries up and usually no trace of it remains in older
strands. At the same time the formation of the ultimate medullary hyphae begins
inside; these arise, as is shown in Fig. 12, as slender lateral branches from the
cells of the zone which produces the medulla, and from the innermost layers of
the rind which are not sharply distinguished from it; these branches elongate
and ramify and enter the axile cavity, and becoming woven together there fill it
up in the manner which has been already described. As the zone which produces
the medulla always consists of several layers of cells, the hyphae which proceed
from its outer layers into the cavity must force their way between the inner layers,
which may become much displaced and squeezed together, and this gives rise to
the irregularly constructed boundary zone between the medulla and the rind which
was mentioned above. A subterranean strand may form branches of the same
kind in varying number and with no regular arrangement. At the point where
a branch subsequently appears, a new formation in the form of a thick cushion
of pseudo-parenchyma is developed within the inner layers of the rind by shoots
from its cells, and the growing point of the strand emerges in a few days from

CHAPTER II.—DIFFERENTIATION OF THE THALLUS—-MYCELIAL STRANDS. 27

the cushion, and breaking through the rind of the parent-strand grows in the manner
which has already been described. Its final medullary hyphae become continuous
with those of the medulla of the parent-strand. Schmitz first observed that, at
least when old strands are cultivated in a damp chamber, the place of every future
branch is indicated some days before its emergence by the appearance of a floccose
tuft of hyphae 4—1 mm. in size, arising partly beneath, partly also according to
Hartig out of the surface of the parent-strand, which decays and disappears as
the branch is formed.

The stronger subcortical strands and the membrane-like expansions in the
living tree are said by Hartig to be similar to the subterranean ones just described in
structure and development, except in respect
of certain differences arising from difference
of form, the somewhat smaller masses of
tissue, and the fainter tinge of brown on
the outer layers of the rind or the entire
absence of that colour. Very delicate myce-
lial membranes and slender tufts of ramifying
branches, which frequently arise on the edge
of the larger mycelial body, have a more
simple structure and consist only of hyphae
of the rind. There is one important pecu-
liarity in all these strands and expansions,
that the numerous hyphae which stand out
like hairs from the surface force their way
into the tissue of the rind and wood, and
spread and ramify there, and are organs by
which the Fungus takes up its food. They
often form bladder-like swellings in the
tracheides of the pine-wood which they
decompose, reminding one of the inner
layers of the rind of the strand, and their
number in the tracheides may be so large
as to fill them with a tissue of bladder-like r
nn tasted ice ote ge se goal ani tae

Brefeld has completed our knowledge of der egg cern medullary hyphae 4 grow as
the life-history of the mycelium of Agaricus
melleus by growing it from spores in an artificial nutrient solution (decoction
of plums), A delicate branched radiating primary mycelial hypha was developed
in about eight days from the germ-tube which issued from the spore cultivated
on a microscopic slide. Thick tuft-like branchlets from single branches of the
hyphae or from several adjacent ones then appeared in the centre of the circular
expansion which was some millimetres in size; these tufts raised themselves erect
and became united together into clews as large, according to the figures, as a
good-sized pin’s head, after the manner of the sclerotia to be described below in

* R. Hartig, Die Zersetzungserscheinungen d. Holzes, Pp. 59.

28 DIVISION I.—GENERAL MORPHOLOGY.

section VIII. The clews assumed a pseudo-parenchymatous structure owing to the
swelling of the cells of the hyphae, and the greater part of their surface acquired a brown
colour. Then one or several growing points appeared on most of the clews, always at
isolated uncoloured spots in the part which did not project above the nutrient solution,
and from these points mycelial strands were developed of the subterranean form
just described. The primary mycelial hypha ceases to grow when the formation of
strands commences; the strands also cease to grow as soon as the supply of nutri-
ment is exhausted. When cultivated on bread or with a larger supply of the
nutrient solution they developed vigorously and branched copiously, and showed all
the important points of the subcortical form described above. They remained
uncoloured beneath the substratum, and cessation of growth in length was followed
by specially copious development of gelatinous hyphae spreading from the surface,
and forming on the top of the fluid thick membrane-like patches of wefted covering
with a vesicular pseudo-parenchymatous structure, and with the cell-walls coloured
brown where they were in contact with the air. After a winter rest of several months’
duration a large number of strands of the subterranean form were again produced
from the cultivated specimens, being fed by them, and they were seen to make their
way into the roots of living pines, where their further subcortical development
was also observed.

The development of the sporophores, which will be described in Division II,
begins according to Hartig on strands of both kinds in the same manner as the formation
already described of similar branches on the strands.

Further details and variations, the great abundance of which is not to be wondered
at, considering the great variety of form and adaptation displayed by the strands of
Agaricus melleus, are to be found in the works of Hartig and Brefeld which are
cited further on. I have endeavoured to correct my own former statements, and some
also of those writers themselves, from these researches and some more recent ones
of my own. Some statements have not been satisfactorily explained even by these
investigations ; among them a former remark of mine in the first edition of this book,
that old and strong specimens of the subterranean form ‘have often an uneven and
wrinkled rind, in which through subsequent luxuriance of growth the number of the
cell-layers is considerably increased and their arrangement is disturbed. I often
but not always found inside these specimens a brown zone concentric with the rind
from which it is divided by a narrow layer of ordinary medullary tissue, and enclosing
a strand of the latter tissue. This zone consists of hyphae with brown membranes
very tightly interwoven with one another, but in other respects resembling the ordinary
elements of the medulla, into which it passes without a break. 'Eschweiler’s account
of the structure of the Rhizomorphae is founded on the examination of such specimens.’

Future investigations will perhaps clear up these less important points. Greater -
interest attaches to the question, whether the first development of the mycelium
observed by Brefeld, and especially the primary formation of the subterranean strand,
is an invariable occurrence in Agaricus melleus, or whether perhaps the subcortical
formations do not proceed directly. from the mycelial hyphae, when the spores
germinate on a substratum which renders parasitic growth possible, that is upon
the living root of a conifer.

The history of our knowledge of the mycelium of Agaricus melleus is somewhat
remarkable. Before R. Hartig discovered that the strands belonged to this Hyme-
nomycete, they were supposed to represent a distinct species of Fungus which was
named by Roth Rhizomorpha fragilis, or the two forms, the subterranean and the
subcortical, were made two distinct species, Rhizomorpha subterranea and Rh.

CHAPTER II.—--DIFFERENTIATION OF THE THALLUS.—MPCELIAL STRANDS. 29

subcorticalis, Persoon. The attempts to find the fructification of these Fungi led to the
most divergent views; but there is no need happily to repeat here and criticise
the complete enumeration and examination of them which was given in the first
edition of this work. Some writers, as P. de Candolle, Eschweiler, Acharius, and more
recently Fuckel, endeavoured to prove the Rhizomorphae to be true Pyrenomycetes,
and assigned them perithecia, some of which, according to Tulasne, were in fact
merely galls, while others belonged to real Pyrenomycetes, which had grown on
or close to the strands of the Agaric. Otth regarded as their fructification a species
of Stilbum or Graphium which is sometimes found on old strands in the
form of small black bodies of the thickness of a bristle and 3-4 mm. in length
and giving off spores by abjunction, a view which was supported by the resem-
blance of their structure to that of the rind of the strands, and which after all
may in a limited sense still be correct. The question can only be decided by the
history of the development of the Stilbum ; but this is not known, and the species may
for the present be considered with greater probability to be a parasite on the strands.

Other writers, as Palisot de Beauvois, and in more recent times Caspary and
Tulasne, looked upon the Hymenomycetes, especially the woody Polyporeae, as
the sporophores of the Rhizomorphae, partly because the two were so closely
associated in their growth, and partly because these observers confounded the
strand-like or membranous mycelia of the former plants with the strands of Agaricus
melleus, the characteristic structure of which they did not properly distinguish.
Hence Caspary, for instance, brings the Rhizomorphae themselves into genetic
connection with the sporophores of quite different species of Polyporus, Trametes Pini,
and Agaricus ostreatus.

The name Rhizomorpha we now know to be superfluous; it may and should
be dispensed with, as I have myself done above. The same may be said of the
name Xylostroma mentioned in the preceding pages, as also of the names Himantia,
Ozonium, Hypha, Hyphasma, Fibrillaria, Ceratonema, all of Persoon, Byssus, Dill.,
Dematium, Lk. (in part), Corallofungus, Vaill. They were applied, as is well
known, since the time of Palisot de Beauvois to sterile mycelial strands which
sometimes attained a great size in damp wocds, cellars, and mines, but their connection
with distinct forms of sporophore, owing to the slight attention which was formerly
paid to the study of mycelia, was never actually decided.

The forms, which Fries! regarded as a distinct genus Anthiria, may also be mentioned
in connection with sterile mycelial strands of doubtful affinity. The Anthinae, of which I
am here speaking, and from which I exclude the section Pterula, Fr. because these appear
to be fertile, are cylindrical or ribbon-shaped bodies an inch high on the average and
about 1 mm. in thickness, which grow erect from a floccose mycelium largely developed
in decaying wood and leaves, and branch in their upper part dichotomously or in
a palmate manner. They are either ofa brightred colour (A. flammea, A. purpurea) or
pale brown (A. pallida). They consist of a strand of parallel hyphae firmly united
together by a homogeneous connecting substance, and are formed by the union
of the hyphae which spread abundantly through the substratum. The bundle is
divided at the upper end, or its hyphae separate from one another and spread on all
sides and form the bifurcating or palmate extremities. Specimens are not unfrequently
found with the upper end of the plant bent down towards the ground, and there
separated into a floccose mycelium or even into net-like anastomoses. I have myself
never seen a sporophore in these forms, though Fries says of A. flammea, ‘ affusa aqua
secedunt sporidia’ The small cells laterally attached to the hyphae, which I have
occasionally found in A. pallida, and which I formerly spoke of as spores, I am
now inclined to regard as very doubtful structures.

! Pl. homon. 169.

30 DIVISION I.—GENERAL MORPHOLOGY.

Section VIII. The name sclerotium has been given to certain thick tuber-like
bodies formed on the primary filamentous mycelium which proceeds from the ger-
minating spore; these, which are storehouses of reserve-material, become detached
from the mycelium when their development is complete, usually remain dormant
for a considerable time, and ultimately expend their reserve-material in the production
of shoots which develope into sporophores.

The sclerotia are generally exposed on the surface of the substratum, or they are
formed on the walls of broad fissures in it or sometimes even in the close tissues of
phanerogamous plants.

Their form and average size vary much according to the species, the latter being
dependent also on the quantity and quality of the food supplied to them. The
sclerotia for example of Typhula variabilis are small spheres usually of the size
of a mustard-seed, those of Sclerotinia Sclerotiorum differ extremely in shape and
may be smaller than a pea or as large as a hazel-nut, or form shapeless cakes some-
times an inch in breadth; the sclerotia of species of Claviceps are horn-shaped blunt
triangular bodies which may be more than an inch long and some millimetres in
thickness, or scarcely 1 cm. in length and 1 mm. in breadth, according to the species
and the nutrition.

The structure of these bodies in their mature resting state is, in some points of
chief importance, the same in all the species. They consist chiefly of a uniform
compact tissue, the sedz/la, which, with a single exception noticed below in paragraph
d, is surrounded by an outer layer of peculiar structure forming the rzzd or outer coat.
Both parts contain comparatively little water. The medulla is a close weft of hyphae
or a pseudo-parenchyma, the elements of which are pale-coloured or colourless and
contain a large quantity of reserve food-material ; this in some cases takes the form of
a great thickening along with gelatinisation of the membranes of the cells, the lumina
of which are narrow and contain little solid matter, as in species of Sclerotinia and in
Typhula gyrans, &c., or their cell-walls continue thin and the food-material is in the
form of large accumulations of fatty matters, as in Claviceps, or of fine-grained proto-
plasmic substances, as in Coprinus stercorarius and others. Exact investigation of,
the reserve material has been made only in the case of the sclerotia of Claviceps?.
The rind is composed of one or more layers of cells which have their membranes
wholly or partially sclerosed and dark-coloured, and are poor in solid contents.

Within the limits of this general structure, which is common to these bodies,
there are special structural arrangements which vary much in the different species.
Outward likeness is not always accompanied by agreement in their internal
structure, which may also be like or very unlike in nearly related species,

The following details, most of which appeared in the first edition of this work, will
illustrate these points.

a. The sclerotia of the Sclerotinia-Pezizeae (Peziza tuberosa, P. Sclerotiorum,
P. Fuckeliana, P. Candolleana, P. ciborioides, P. baccarum, &c.) have a thin, black,
smooth or rough rind, and a medulla which in the dry state is of a white or whitish
colour. The latter is a firm gelatinous tissue of cartilaginous texture without any

1 Flückiger, Pharmacognosie d. Pflanzenreichs ; see before on page 17.

CHAPTER II.—DIFFERENTIATION OF THE THALLUS.—SCLEROTIA. 31

air-conducting passages, as in P. Fuckeliana, or with comparatively few of them.
Its hyphae are cylindrical and septate, and interwoven with one another in every
direction ; hence in thin sections of the sclerotia their lumina appear in all possible
forms according as the section passes through them transversely, obliquely, or
longitudinally (Figs. 13, 14). The cells in the moist state contain little else than
a watery fluid; in the dry state they contain air. Towards the rind the hyphae
are divided into short cells, and in sections therefore most of the cells have a circular
outline. j

The rind consists of isodiametric roundish-cornered cells which have firm dark-brown
membranes and adhere closelyto one another. In small forms (Fig. 13) it is composed
of one or two layers of cells, in larger (Peziza tuberosa, P. Sclerotiorum, Fig. 14) of
three or four or more layers, and then the cells are usually arranged in irregularly
radiating rows perpendicular to the surface. It can be easily shown in most cases
that the elements of the rind are those segments of the medullary hyphae which lie
nearest to the surface of the sclerotium.

The breadth of the hyphae varies in different species and sometimes in different
individuals.

EN

FIG. 13. Piece of a thin transverse section FIG. 14. Thin section through a mature sclerotium of Scterotinta Sclerotiorum,
through asclerotium of Sclerotinia Fuckeliana ; Libert, showing the rind and adjoining medullary tissue. Magn. 375 times.
rthe rind. Magn. 390 times.

Many of the forms which belong to this group occur on the surface of the part of the
plant on which they grow, others inside them in their decomposing substance. The
former (Peziza tuberosa, and P. Sclerotiorum frequently) show the structure, which has
been described, quite perfectly. Some of the latter, as P. Sclerotiorum, often enclose
isolated dead cells or larger portions of the tissue of the part of the plants, which they
inhabit, in their own substance, as Corda pointed out. The foreign bodies thus
enclosed are irregularly and inconstantly distributed through the medulla, and
are sometimes surrounded by a layer of dark-brown cells of the rind.

The smaller sclerotia of this type, which are found growing on decaying leaves
(Peziza Candolleana, Lev., P. Fuckeliana), regularly take possession of the substance
of the leaf at the points where they are developed. They are weal-like swellings
on the leaf, formed of the tissue-elements of the sclerotium, among which the dead
elements of the leaf are interposed, though more or less displaced and separated
from one another. The way in which the sclerotium takes possession of the tissue
of the leaf is different in different species. The sclerotium of P. Fuckeliana for
example (Fig. 19) inhabits only the parenchyma and epidermis of the leaf of the
grape-vine, but sometimes it grows even over the hairs on the leaf and so appears

32 DIVISION I.—GENERAL MORPHOLOGY.

to be spikey ; it often appears along the veins of the leaf, but always outside the
wood-bundles. I found the sclerotia of P. Candolleana on oak-leaves, but there also
only in the parenchyma. But the sclerotium of a small Peziza which inhabits the
leaves of Prunus insinuates itself among all the elements of the veins of the leaf.

d. The structure of the sclerotia of several of the Hymenomycetes, especially Agaricus
cirrhatus, P. (?), A. tuberosus, Bull., and Hypochnus centrifugus, Tul., differs
little from that of the first type. The chief difference is that the cell-walls in the rind
are not a dark but a yellow brown; the surface of the rind is in most cases tolerably
smooth, but in Hypochnus centrifugus it is uneven or felted over with the remains of
the hyphae which surround the sclerotium in its younger state. The hyphae of
the medullary tissue and their membranes are of varying thickness according
to the species; they are in most cases chiefly filled with a watery fluid or with
air; in Hypochnus centrifugus they contain drops of oil. I have never found
tissue-elements of the host enclosed in the medulla even of those of the above
mentioned sclerotia, which had developed in the interior of decomposing parts of plants
(Mushrooms).

c. A somewhat different structure from the above is seen in a sclerotium in
Rabenhorst’s Herb. mycol. Nr. 1791, incorrectly named Sclerotium stercorarium, and
of doubtful origin. Its white medullary tissue consists of thin-walled cylindrical
hyphae which contain a watery fluid, and are usually rather loosely interwoven,
the interstices being filled with air. Towards the surface the medulla passes gradually
into an outer covering of many layers of narrower hyphae, which mostly run parallel
to the periphery and form a tissue without interstices. The inner layers of this
tissue are colourless, towards the outside the membranes become gradually yellow-
brown, and those of the outermost layers are so considerally thickened that the lumina
are much reduced in size. The whole sclerotium is thus surrounded by a firm uneven
rind composed of several layers.

d. The light-yellow Selerotium muscorum, which also belongs to some Agaric,
consists of a web of broad thin-walled hyphae with narrow interstices containing air.
The hyphae, which are not arranged in any order, are composed partly of elongated
cylindrical and partly of short vesicular cells. The latter contain a clouded homo-
geneous yellowish protoplasm, or a watery fluid in which drops of yellow oil are
suspended. The surface of the sclerotium appears to the naked eye of a darker
colour than the centre, but under the microscope the structure is seen to be the
same throughout, and the medulla and rind are not clearly distinguished. Single
surface-cells project here and there as cylindrical papillae.

e. The snow-white medulla of the sclerotium of Coprinus stercorarius, Fr. has
a similar structure to that in Sclerotium-muscorum. It is a pseudo-parenchyma
composed of broad irregularly roundish or elongate-ovoid cells and single cylindrical
hyphae; all the cells are very thin-walled and filled with a colourless, uniformly
and finely granular, somewhat strongly refractive protoplasmic substance, which issues
forth from injured cells and spreads through water and makes it turbid. These
cells form a close tissue which is hard in the dry state, and has more or less
narrow interstices filled with air. The cells of the medulla become suddenly smaller
towards the circumference. The surface of the sclerotium is formed of a firm
apparently black rind which is wrinkled in the dry state. Where this rind borders on the
medulla it shows four or five irregular layers of small cells of the shape and size of the
outermost cells of the medulla, but with brown membranes and apparently always
clear watery contents. This layer is surrounded by the more superficial rind
consisting of three or more layers of large cells usually of irregular roundish outline,
which at the periphery have some resemblance to the largest of the cells of the medulla,
and contain a watery fluid or air within a slightly thickened wall of a dark violet-black
colour. Many of the superficial cells of the rind project irregularly above the rest

CHAPTER II.—-DIFFERENTIATION OF THE THALLUS.—SCLEROTIA. 33

and some are prolonged into short irregular hairs or papillae, while in others the
membrane is irregularly torn on the outer side of the cell and the exterior surface
is thus rendered rough and uneven.

Sf, The sclerotia of some Typhulae, T. phacorrhiza, T. gyrans, T. Euphorbiae, Fuckel,
T. graminum, Karst., &c. have the gelatinous medulla with cartilaginous consistence
of the type a, with slight differences as regards the thickness and firmness of their
membranes in the several species. The hyphae contain a clear watery fluid which
sometimes has granules sparingly distributed through it; in T. graminum only they
are densely filled with homogeneous turbid protoplasm. The rind in these species is a
single layer of cells of uniform height connected by their sides without interstices,
which are evidently the peripheral segments of the medullary hyphae, unlike them
as they may be in structure. The cells are tabular or shortly prismatic in shape,
their lateral walls often curved and sinuous; the inner and lateral walls are slightly,
the outer walls very strongly thickened in the manner of the outer wall of the
epidermal cells in vascular plants, and have their outer surface smooth (Fig. 15 c) or
warted (Fig. 15 «, 4). The rind is thus remarkably like the firm epidermis without
stomata of many vascular plants.

g. In the sclerotia of Typhula variabilis, Riess, and Peziza Curreyana the
structure of the rind is essentially the same as in the last type, but the white or in
P. curreyana the rose-red medullary tissue is a weft of cylindrical hyphae with

FIG. ı5. @ and 3 sclerotium of 7yphula phacorrhiza. a piece of a thin transverse section ; r—r rind-cells, g—g outer layers

of the same. 5 piece of the rind flattened out, seen from the outside ; at s the outside of outer layers only is seen without the

lateral walls of the cells. c cortical layer of the sclerotium of 7yPAula gyrans flattened out and seen from the outside. Magn.

390 times.
air-spaces. The hyphae are thin-walled in Typhula with dense, granular conteits ;
in P. curreyana the membrane is thickened and stratified, and the medullary tissue
is more compact towards the periphery as is the case in type a.

hk. The sclerotia of species of Claviceps, the blunt trilateral horn-shaped bodies
which develope in the flowers of the Gramineae and Cyperaceae at the expense of
the ovary and are known by the name of ergoZ, consist in the mature state chiefly
of a dirty-white medullary tissue surrounded by a violet-brown rind. The medulla
has the character of a pseudo-parenchyma formed of cylindric prismatic cells, which
are on an average from one to four times as long as broad. The cells are arranged
in straight or sinuous longitudinal rows, and the history of their development shows
that they possess the characters of the fungal hyphae. This may also be clearly
seen even in ripe sclerotia, in the interior of which clefts and fissures are often
found clothed or loosely filled with a thin felt ; sections show that the felt is composed
of interwoven hyphae, which spring as branches from the rows of cells of the
compact tissue and have the same characteristics, except that their weft is looser.
The medulla has usually shorter and broader cells towards the periphery of the
sclerotium than in its centre. The cells are everywhere provided with tolerably
thick colourless membranes, and are usually firmly grown together on every side
without interspaces. They contain large colourless drops of oil.

[4] D

34 DIVISION I.—GENERAL MORPHOLOGY.

The medulla is surrounded at first by an inner stratum of the rind which is at
every point firmly connected with it, and is composed of one or two layers of cells
with contents showing no oil, and with membranes that are strongly thickened often
more on the outside than on the inside and of a dark violet-brown colour. This inner
stratum of the rind is,enclosed by an outer portion formed of a few or even as many
as twenty layers of longitudinally arranged or irregular branched rows of cells;
the cells are narrow and their membranes are of a pale violet-brown. This is the
thin pale-violet coating, often with longitudinal stripes or interruptions, which clothes
the surface of the fresh sclerotium and may be easily broken or rubbed off from the
firm inner rind.

All sclerotia, it would appear, develope as secondary formations on a primary
sporogenous filamentous mycelium. They arise from a single branch of a mycelial
filament which has quickly produced a tuft of many branchlets; this is the case in
Coprinus stercorarius, Typhula variabilis, and T. gyrans. In others, as in the forms of
Sclerotinia, several adjacent branches of the primary mycelium take part in the forma-
tion from the first. In both cases the young sclerotium soon rises above the substratum
as a small tuft of loosely tangled hyphal branches in all essential points similar to the
primary. Then in Sclerotinia Sclerotiorum the filaments of the tuft grow vigorously
and branch and coalesce repeatedly by means of H-shaped cohesions, and thus the
tuft itself developes into a dense white ball of the size of the sclerotium ; till this size is
reached, the structure of the hyphae remains as it was originally, the new branches
are often slenderer than the primary hyphae and their character is uniform in all parts
of the ball. The interstices in the tissue contain air, the surface is rendered finely
hairy by the presence of slender spreading branchlets of the hyphae, and the whole
body is soft and can be easily compressed into an extremely small compass. But
from this time by new formations in its interior, and afterwards by expansion_of the
cells already formed, the tissue constantly increases in size and firmness. Lastly the
thickening of the membranes commences, which is characteristic of the species, and
this is accompanied with a partial disappearance of the air-spaces and the differentia-
tion into medullary and cortical layers. This process of development begins in the
interior of the tissue and advances rapidly towards the circumference. The outermost
layer of the white ball takes no part in it, but remains for a time as a white felted
covering on the rind which is distinct from it, and ultimately shrinks to nothing and
disappears. The ripe sclerotium becomes detached from its felted environment as a
body of sharply defined form and outline.

Sclerotinia Fuckeliana exhibits the same phenomena when cultivated upon a
microscopic slide ; but, as might be expected, these are modified by the nature of its
environment when the sclerotium is developed spontaneously inside the tissue of a
phanerogamous plant. Peziza ciborioides also behaves in a similar manner, but shows
some specific variations in its development.

The tuft of hyphae which is the commencemet of a sclerotium of Typhula
variabilis rises above the substratum in which the primary mycelium has spread its
ramifications’. The branches of the tuft become woven together into a smooth
white spherical body of small size, which is attached to the substratum by a short
and slender stalk. The sphere enlarges rapidly by the formation of new cells and

1 The substratum in the natural way of growth is formed of decaying leaves in winter and spring ;
Brefeld employed nutrient solutions for the purpose of artificial culture.

CHAPTER II.—-DIFFERENTIATION OF THE THALLUS,—SCLEROTIA, 35

branches in all its parts. It is entirely formed at first of uniform thin-walled much
branched hyphae, which are rich in protoplasm and closely woven together, but not
without air-spaces. Those parts only of the hyphae which form the outer moist surface
of the sphere have no interstices between them ; if we examine a sclerotium in a very
early stage of its development we see that the surface is formed ofa layer of short cells of
uniform height, which are segments of hyphal branches running in numbers through
the periphery. These cells are at first thin-walled and filled with protoplasm, like
the other portions of the hyphae, and their walls are colourless. Growth by
formation of new hyphal branches continues for some time longer in the centre of
the sphere, and thus the medulla enlarges its circumference considerably, while its
hyphae grow to twice their original size ; but the intertwining of the hyphae remains as
it was before. From an early stage in the development no new cells are introduced
between the previously existing cells of the superficial layer ; but these cells stretch in
every direction, and sufficiently strongly in that of the surface of the sphere to remain
united together into a layer without interstices. Their radial or lateral walls assume
in this way the undulated inflated outline mentioned above in paragraph /, while their
outer membrane becomes thickened to form the covering described in the same place,
and takes the permanent yellow colour or passes through yellow and brownish yellow
to a dark brown; the protoplasm disappears. This formation of rind is continued
also at the point of insertion of the stalk over a layer of cells which lies in the
direction of the surface of the sphere, and the sphere is thus divided off from the stalk
and is ultimately detached from it, while the stalk dries up. The development of
Typhula gyrans follows a similar course. All that is known of the development of
other sclerotia, excepting that of Claviceps, agrees with the processes above described,
-though the final differentiation is accompanied by certain variations in detail, as will be
inferred from the statements in paragraphs a to g; in this matter Brefeld’s careful
description of Coprinus stercorarius should be consulted.

The sclerotia, of the development of which we have been speaking, are not all
formed on morphologically definite spots of the primary mycelium, and their number
varies according to the state of its nutrition. When several begin to be formed
near each other, they may unite as they grow into one body; this leads to
the formation of the irregular cakes and crusts mentioned above, especially in
Peziza Sclerotiorum, though it is observed in other species also, as in Coprinus
stercorarius, and in a less degree in Typhula gyrans. Much water is expelled from
all the above sclerotia when the differentiation and final development commence in
them, and appears on their surface in large clear drops. The whole process of
development may under favourable conditions be accomplished from beginning to
end in a few days.

The sclerotia of Claviceps (ergot), concerning which Tulasne’s !zbours have given
us more exact information, show several variations of detail in their development arising
from the peculiar parasitism of the Fungus (Figs. 16,17). The primary mycelium
occupies at first the base of the young ovary in the flower of the Gramineae and
Cyperaceae. In ordinary cases, to which we will at present confine our attention, it
spreads rapidly through the entire ovary, with the exception of its apex and some-
times also of the inner layers of its wall; the ovary is thus changed into a white
Fungus-body of nearly its own shape, with a surface marked with deep narrow

D2

36 DIVISION I.—GENERAL MORPHOLOGY.

curved furrows ; and as gonidia are formed on the surface in a way that will be after-
wards described (see Division II) the body may be termed a gonidiophore (Fig. 16).
The hyphae of the Fungus-body must necessarily make their way for some distance
from the ovarian base into the floral pedicel, for it is difficult to conceive of any other
mode of supplying food to the Fungus; but we have no exact information on this
point. When the gonidiophore is fully formed, the beginning of a sclerotium makes
its appearance in the torus at its base and on the mycelium, which is supposed to
spread through it, in the form of a small somewhat elongated fungal body enclosed
in the white tissue and distinguished by its greater density (Fig. 16 4, s). It is
formed at first of slender delicate separable hyphae which are continuous with
those in the vicinity, but are somewhat firmer and more closely compacted. Its

Fic. 16. Claviceps purpurea, Tul. a young ovary of FIG. 17. Claviceps purpurea, Tul., on Secale cereale.
Secale cereale penetrated and covered with the gonidio- a seen from without. 4 median longitudinal section. The
phore, seen from without; the hairs of the ovary and the sclerotium s rests on the torus and carries up the dry-
remains of the style g project at the apex from the fungal ing gonidiophore ? on its apex. After Tulasne. Slightly
inve é longitudinal section gh a similar stage magnified,

in the development from Seca/e; s commencement of
the sclerotium. c¢ similarly young state of the Fungus on
the .pistil of Glycerta fluttans, the Fungus projecting
beyond the apex of the ovary. After Tulasne. Slightly
magnified.

surface soon acquires a violet hue, the superficial cells beginning to assume the
character of the future rind. It now increases in thickness and elongates into the
well-known horn-shaped body, which is attached at its base to the torus and projects
above from between the paleae. The course of its development still requires more
exact investigation. Its growth in the longitudinal direction is no doubt maintained
by continued addition at the base. The increase in thickness of each transverse
section above the base must in a great measure be due to the expansion of cells
already formed, since these are more than four times broader in the fully
developed parts than in the younger. The gonidiophore ceases to grow as soon as
the sclerotium begins to be formed, and being detached from the torus as the
sclerotium enlarges it is carried up like a cap on its apex, and there shrivels up and
sooner or later falls off (Fig. 17).

CHAPTER II.—DIFFERENTIATION OF THE THALLUS.—-SCLEROTIA. 37

The development of these sclerotia is slow; it required for instance about four
weeks, according to Tulasne’s observations, in the months of July and August in the
flowers of Brachypodium sylvaticum. In this case, when the sclerotia began to ©
develope, drops of a saccharine fluid were observed to appear; but it is uncertain
to what extent they were connected with the formation of the sclerotia or with that of
the gonidia.

It sometimes, but rarely, happens that the Fungus is developed beneath the point
of attachment of the ovary; when this happens the ovary preserves its proper form
and is carried up between the paleae on the apex of the sclerotium, and there withers
away before its time.

The sclerotia when fully formed and matured pass into a resting state, the
duration of which varies in species and in individuals with external and internal
causes, as is the case with seeds, tubers, and rhizomes. It depends on the habits
of life of the species in the natural condition whether the period of rest is
confined for example to winter, as is the case with Claviceps, Peziza Curreyana,”
and P. Duriaei, or to summer, as in Typhula gyrans, T. variabilis, and T. phacorrhiza,
or is not constantly connected with the time of year. In the former case the time of
rest may only be slightly shortened in some species by changing the external
conditions, as the example of Claviceps especially shows.

Sclerotia if kept dry will retain their power of development for a long time
unimpaired ; those of Peziza Sclerotiorum for more thana year, according to Brefeld
for several years, those of Claviceps for about a year; after about that time those
of the latter species and of Peziza Fuckeliana also usually lose their vitality.

The external conditions for the further development of the sclerotia are the
ordinary general conditions for germination, sufficient supply of water and oxygen
anda suitable temperature. The usual procedure under such conditions is as follows.
The sclerotium first absorbs water and swells, and then in a longer or shorter time,
often not till after some months, it sends out shoots at the cost of the food-material
stored up within it, and these develope directly into the sporophores characteristic of
the species. The sporophores in the species which form sclerotia, with the exception
which will be named further on, are compound structures. They accordingly
make their appearance as bundles of hyphae springing as branches from the elements
of the sclerotium, and in two ways according to the species.

In one case (Figs. 18, 19) represented by Claviceps, Sclerotinia Fuckeliana and
S. Sclerotiorum, Typhula gyrans and T. phacorrhiza, the bundle of hyphae arises at
a certain spot in the medullary tissue and from branches of it which originate beneath
the rind ; the latter has no share in the new formations but is pierced through by the
advancing bundle of hyphae. A more minute description of the special circumstances
observed in Sclerotinia will be given in Division II.

In the second case the bundle of hyphae is formed by the ramification of
outgrowths from the cells of the rind, as Brefeld rightly states in the case of Coprinus
stercorarius; whether it is always a single cell that produces these shoots must for
the present remain undecided. Agaricus cirrhatus also shows this formation.

Typhula variabilis is in some respects intermediate between the two cases; here
according to Brefeld the initial bundle of hyphae appears on the surface of the rind,
neither springing apparently from a cell of the rind, nor causing an evident broad

38 DIVISION I.—GENERAL MORPHOLOGY.

fissure in the rind, and formed therefore in all probability from a single branch
proceeding from a peripheral medullary hypha and piercing through the rind.

The exceptional case mentioned above, in which the product of the sclerotium
is not a compound structure, is the formation of simple’ filamentous gonidiophores,
known by the name of Botrytis cinerea, from the sclerotia of Peziza Fuckeliana. In
most of the cases which I have myself examined a bundle of hyphae shoots out from
the subcortical medullary region, and where it has broken through the rind the
hyphae spread in different directions, and each developes into a gonidiophore. But it
sometimes happens that the cells of the rind develope directly into gonidiophores.

In none of the sclerotia that have been examined is the origin of the shoots
connected with a definite predestined morphological spot. Any fragment of the larger
sclerotia, if not too small, can under ordinary circumstances produce them, as Tulasne
showed in the case of Claviceps, and Brefeld especially in that of Coprinus stercorarius.

The number also of the shoots that may proceed from a sclerotium is not
definite in any species ; and some species can produce an almost unlimited number

A

N my

a)
linac i \

IN

ut = |

h
>

FIG. 18. aandc Claviceps serene: 5 C. microcephala, T. aand éscle- Fic. 19. ern Tuckeliana, a very
rotia with mature sporop section zh a sclerotiuin small section
with the young sporophores emerging from the interior, After Tulasne, a a sclerotium, from which a sporophore cut
and 6 nat. size, c slightly magnified. has p d. The

dark spots in in the sclerotium are the dead cells
of the vine-leaf which it has occupied; the
spots and dots at 2 are calcium oxalate
aggregations, Magn. 20 times.

of these primordia (Anlagen) of sporophores on their sclerotia, others cannot do this.
Vigorous specimens of Coprinus stercorarius, according to Brefeld, may produce
hundreds of primordia, of which however few are ever perfected, and if those already
“formed are intentionally and repeatedly destroyed hundreds of fresh primordia as
repeatedly make their appearance. Other species are less productive; Sclerotinia
Sclerotiorum seldom has two dozen sporophores even on strong plants; species with
small sclerotia have usually one only or very few.

The size of the individual sclerotia on one and the same species, other conditions
being the same, generally causes a difference in the number of thé sporophores
which commence and complete their development, and in the vigour of growth of the
latter. Larger sclerotia are on the whole more productive than the smaller.
Claviceps purpurea produces 20-30 sporophores from such large sclerotia as are
formed upon the ears of Secale cereale, but only one or a few weakly ones from the
small sclerotia upon the spikelets of Bromus, Lolium, and Anthoxanthum. Similar
differences arising from the size of the sclerotia are observed also in Sclerotinia
Sclerotiorum and in Coprinus. The relation between size and productiveness is the

CHAPTER II.—DIFFERENTIATION OF THE THALLUS.—SCLEROTIA. 39

same in fragments of a sclerotium as in their corresponding sclerotia. It is natural to
assume, without closer inquiry into the metabolism, that the cause of these phenomena
lies in the difference in quantity of the reserve-material at the disposition’ of the plant
according to the size of the sclerotia or their fragments, and that the not infrequent
irregularities and apparent exceptions to the rule are due, other things being equal, to
differences in quantity or quality in the reserve-material, which may occur also, be it
remembered, where the size of the sclerotia or of its fragments is the same.

The formation of the primordia and the further development of the sporophores is
accompanied by the solution, transformation, and consumption of the food-material
stored up in the sclerotia. The process begins at the point of origin of a primordium and
spreads by degrees through the medullary tissue. In Claviceps, according to Tulasne,
the oil disappears and its place is taken by watery fluid, the cell-membranes become
thinner and ultimately very delicate, and the cells separate readily from one another.
In the sclerotia of Sclerotinia Fuckeliana, S. Sclerotiorum, S.tuberosa, Typhula gyrans,
&c. which are gelatinous witha cartilaginous consistence, the gelatinous thickening-layers
of the hyphae become softer and pale and by degrees scarcely recognisable, so that the
innermost layer only of the membrane can still be clearly seen as a delicate pellicle.
The former firm union of the hyphae naturally comes to an end at the same time ;
and a mass of granular matter which turns yellow with iodine collects in the cavities
of the cells, and diminishes again in quantity as the sporophores increase in number
and size. In Coprinus stercorarius, according to Brefeld, the granular protoplasm of
the cells is replaced by a watery fluid, and the membranes become pale and
undistinguishable. Ultimately in all these cases the medullary tissue almost entirely
disappears. The rind at first takes no perceptible part in these changes; it remains
behind after the disappearance of the medulla as a soft sac which collapses and decays.

These processes take a longer or a shorter time in different cases. In Brefeld’s
culture of Coprinus stercorarius they were over in 7-10 days. In most species they
take much longer time. Sclerotinia Sclerotiorum, for instance, may put out new
sporophores one after another during some months from one sclerotium, and develope
them slowly before the supply of food is exhausted. I have found sclerotia of
Agaricus cirrhatus (see on page 37), which had developed one or more sporophores
and fully matured them, not sensibly different in consistence and structure from others
which had not yet produced any; they might therefore repeat the production of
successive sporophores and perhaps during a considerable time ; but this point
remains to be determined.

Some sclerotia, as those of the Sclerotinieae, of Coprinus stercorarius and
Claviceps, are able in the mature state and as long as they retain their vitality to form
new rind over wounds, such as cut surfaces which reach to the medullary tissue,
provided they are exposed to the air but are protected from desiccation. The new
rind resembles the old ordinary tissue in all essential points. It is formed by the
medullary hyphae exposed by the wound sending out branches, which become woven
together into a delicate felt and cover the surface of the wound. The inner layers of
this covering which are next the uninjured medullary tissue then develope into a new
rind, while the outer ones dry up and disappear. If such wounded places are kept
in a nutrient solution, the branches put out by the medullary hyphae on the exposed
points may, in the Sclerotinieae at least, develope into vegetating mycelial hyphae

40 DIVISION I.—GENERAL MORPHOLOGY.

instead of forming new rind. The sclerotia of the Typhulae in which the tissues are
very distinctly differentiated appear not to be capable of these acts of regeneration.

The following remarks are intended to illustrate and complete what has been stated
above. ,

The production of the primordia of sporophores from the cells of the rind of
Coprinus stercorarius is given on the authority of Brefeld. It is not strange in
itself, even in presence of the facts illustrated in Figs. 18 and 19, that the superficial
cells of the sclerotium should remain capable of further development and of branching,
and that the ordinary distinct division of labour between the protecting rind and
the medulla should in some cases not be observed. There is therefore no antecedent
difficulty in admitting a third mode of production such as Brefeld gives in the case
of Sclerotinia Sclerotiorum, in which the medullary cells and cells of the rind both par-
ticipate. But I have not admitted this case into my account because the facts will not
bear this interpretation. Young shoots always spring in this species from the medulla
in the peculiar manner which will be described in Division II, and burst through
the rind to reach the surface. In somewhat older specimens, such as those which
are very beautifully and correctly portrayed in Brefeld’s Table viii. Fig. 9, the true
state of the case is obscured by the circumstance that the superficial cells of the
sporophore from the point of emergence are very like those of the rind of the
sclerotium in shape and in their dark colour, so that the new cells appear to be
directly continued into the superficial cells. Thin sections even in more advanced
states of growth under sufficient magnifying power show that the case is as I have
stated it, and exhibit clearly the arrangement of the black superficial cells, which
are the extremities of hyphal branches proceeding from branches of the emerging
tuft of hyphae and passing to the surface in diverging curved directions.

That the shoots from the sclerotia in the cases described above should always
have been termed primordia of sporophores requires no special explanation, even in
the case of Sclerotinia Sclerotiorum where they may under unfavourable circumstances
develope in the ground into long branched strands. Even the normal sporophores
of this Peziza may be branched, and the branches of the strands may under favour-
able conditions of development revert to the normal sporiferous state. Brefeld indeed
saw them on several occasions produce a filamentous mycelium which subsequently
formed sclerotia ; but these are monstrous developments such as occur also elsewhere,
the exceptional cases that confirm the rule.

It is true that phenomena have been reported in connection with the formation
of shoots from sclerotia, which vary from the descriptions in the text; but more
searching investigation is needed in all these cases. Thus Tulasne saw sclerotia
of Hypochnus centrifugus, which had been placed in damp sand in the end of April,
produce in August and September a filamentous mycelium like a spider’s web, which
subsequently developed the ordinary sporophores of Hypochnus. As regards the
connection of the mycelial hyphae with the sclerotium it is merely stated that they
spread in every direction from its surface. The consistence and structure of the
sclerotia remained unchanged after the production of shoots; hence Tulasne rightly
considers our knowledge of them as not yet complete.

Tulasne has already pointed out that Léveillé’s older statement, that a floccose
mycelium is first produced from the sclerotia of Agaricus grossus, A. stercorarius,
A. racemosus, and A. tuberosus, and afterwards sporophores from the mycelium, is
founded on a mistake.

Another exceptional occurrence, demanding more critical investigation, is described
by Micheli! as taking place in Peziza Tuba, Batsch, a species which seems scarcely
to have been examined since his time. The sclerotium as it lies in the ground puts

1 Nova plantarum genera (1729), p. 205, ‘ Fungoides, No. 5.’

CHAPTER I1.—DIFFERENTIATION OF THE THALLUS.—SCLEROTIA. 41

forth a number of erect sporophores in the spring, and forms a new sclerotium destined
to produce sporophores i in the succeeding year. The exhausted sclerotium of the previous
year is usually still in existence when the new one is formed, so that the underground
portion of the Fungus consists of three small tubers of unequal size.

Historical remarks. Although it has long been known that the sporophores: of
certain Fungi, species of Typhula and Agaricus and some others, aré developed
from small tuber-like bodies, our more exact knowledge of the nature of the sclerotia
is derived from an excellent publication of Léveillé which only appeared in 1843,
and even this work attracted little notice till Tulasne again called attention to the
subject and threw new light upon it by his work on Claviceps in 1853. Up to that
time the greater part of the sclerotia were considered to be independent representatives
of distinct species, and the name Sclerotium was introduced by Tode! to designate
the genus formed by the supposed species, each with its own specific name.

Some fifty species of Sclerotium were described by Fries in his Systema mycolo-
gicum and his Elenchus; the number was subsequently increased to eighty and
additions to it are still made by writers, who prefer the hasty publication of imperfect
observations to more prolonged investigation.

It appears, as has been shown above, that we are at the present time acquainted
with the development and especially with the sporophores of a considerable number
of sclerotia. Others are less perfectly known, in some only the mature sclerotium
has been seen. Undescribed sclerotia are still not unfrequently found in examining
Fungi. Appended is a list of the species of Fungi Which are at present known or
supposed to form sclerotia, together with the old specific names of the sclerotia
» wherever they have been ascertained.

1. Peziza tuberosa.—P. Tuba, Batsch (Micheli,‘l. c.), P. Sclerotiorum, Lib. Sclero-
tium compactum, S. varium), P. Candolleana, Lev. (Sclerotium Pustula), P. Fuckeliana
(Sclerotium echinatum, Fuckel) ; the two last named Pezizas are in all probability iden-
tical, and to them belong the gonidiophores known as Botrytis cinerea, P. (B. erythropus,
Lev.), and the ‘Sclerotium durum’ from which these spring. The little Peziza men-
tioned in par. a, p. 32, as growing on the veins of the leaves of Prunus is very near to these
species; its sclerotia found on the same leaves were incorrectly named Sclerotium
areolatum, Fr. in my first edition.

Peziza ciborioides, Fr. (Hoffmann).—P. baccarum (Schröter).

P. Curreyana, Berk. (Sclerotium roseum, Kneiff).

P. Durieana, Tul. (Sclerotium sulcatum, Desm.).

The above Pezizas with some others have been made a separate genus Rutstroemia,
by Karsten (Mycol. fennica) and Sclerotinia by Fuckel (Symbol. mycolog.).

Peziza ripensis, Hansen. :

2. Claviceps purpurea, Tul., C. microcephala, Tul., C. nigricans, Tul. (Sclerotium
Clavus, DC.).—C. pusilla, Cesati.

Hypomyces armeniacus, Tul.

Vermicularia minor, Fr., also Xylaria bulbosa, P. (see Tul. Carpol.).

3. Typhula lactea, Tul.—T. Todei, Fr.—T. caespitosa, Ces.—T. Euphorbiae, Fuckel
(Sclerotium Cyparissiae, DC.?), T. graminum, Karst. (Sclerotium fulvum, Fr.), T
variabilis, Riess (Sclerotium Semen, Tode if the cortex is dark-brown, Sclerotium
vulgatum, Fr. if it is yellow).—T. erythropus (Sclerotium crustuliforme, Dsm.).—T.
phacorrhiza (Sclerotium scutellatum, A. S.).—T. gyrans (Sclerotium complanatum,
Tode). I give the names in the two last species on the authority of Fries, Hymeno-
mycetes Europaei, 1874. Leveill€ had given the name of Clavaria juncea to the
sporophores growing out of Sclerotium complanatum, and in my first edition I gave

+ Fungi Mecklenburgenses selecti, p. z.

.

42 3 DIVISION I.—GENERAL MORPHOLOGY,

the names Clavaria complanata and C. scutellata after the sclerotia to the two
species which are scarcely distinguishable except by the sclerotia,

Pistillaria micans (Sclerotium laetum, Ehr.).—P. hederaecola, Ces.

Clavaria minor, Lév. (which also belongs to Typhula).

4. Hypochnus centrifugus, Tul.

5. Coprinus stercorarius, Fr. (Sclerotium stercorarium), C. niveus, Fr. (Hansen.)

Agaricus racemosus, P. (Sclerotium lacunosum).—A. tuberosus, Bull. (Sclerotium
cornutum).—A. cirrhatus, P.(?) is the name which I have given above to the small
white Agaric which grows from Sclerotium fungorum. Other Agarics are also said
to form sclerotia: A. tuber regium, Fr., A. arvalis (Sclerotium vaporarium).—A.
grossus, Lév., A. fusipes, Bull., A. volvaceus (from Sclerotium mycetospora, Nees
in Nov. Acta Nat. Cur. XVI, 1), &c. Sclerotium pubescens, P., Sclerotium truncorum,
Fr. were supposed to be connected with such Agarics, on which point see Léveillé
and Tulasne. The statements and determinations are many of them doubtful, and
more accurate investigations are required.

6. Tulostoma pedunculatum, Tul. (Schröter).

There are a large number of tuber-like compound Fungus-bodies the real character
of which is still doubtful; our ignorance of their structure or development makes
it impossible to decide whether they are sclerotia or some other formation. Among
these are Pietra fungaja of South Italy, which is formed of the mycelium of Polyporus
tuberaster, Jacq. rolled up iftto solid masses with bits of soil, stones, and the like;
and the tuberous fungoid bodies named Mylitta, Sclerotium stipitatum, Berk.,
Sclerotium Cocos, Schweinitz, which grow beneath the-surface of the ground to the
size of a fist or a head and are known only in the sterile state, with some others.
Swellings in the substance of phanerogamous plants such as the tubercles on the
roots of the Leguminosae, which were once mistaken for sclerotia, require no
further notice here.

Section IX. Besides the sclerotia which have been described above with
well-marked characters morphological and biological there is a motley assemblage of
compound Fungus-bodies, which approach the sclerotia in their biological character,
but cannot be classed with them from a strict morphological point of view. Such
bodies may be termed sclerotioid, or, for brevity’s sake, simply sclerotia, if we do not
thereby infer their identity with true sclerotia. The biological agreement between these
bodies and sclerotia consists in similarity of structure, in their being storehouses
of reserve-material and in their normally passing through a period of rest, after
which they proceed to a further development. Morphologically they are

1. Transitory resting stages of mycelia, which under favourable circumstances
again develope into filamentous mycelia. Such are the small fatty tubers which are
the resting stage of the mycelium of Hartig’s Rosellinia quercina, and perhaps for-
mations like Sclerotium Cocos and others mentioned above as of doubtful character.

2. Perithecia, which when developed enter upon a long period of rest,
and assume at the same time the form and structure of a sclerotium; these do
not ultimately produce sporophores, but develope in their interior the asci, which
are the characteristic organs of reproduction in perithecia. Of this kind are some
species of Pleospora and Penicillium, which will be fully described in Division II.
The ‘sclerotia’ of the Aspergilli of Wilhelm are certainly homologous with the
perithecia of Penicillium and are also biologically analogous with them.

3. The bodies, which may still retain the old name of xyloma, and which differ
for the most part from sclerotia only in their less definite shape and outline, and in

Ny

CHAP, II—DIFFERENTIATION OF THE THALLUS,— SCLEROTIOID BODIES. 43

not sending out sporophores as branches, but in producing sporogenous receptacles
in their interior. Well-known examples are the Ascomycetes of the genera Rhytisma,
Polystigma, Phyllachora and many of their allies which live on leaves. They develope
in the substance of the leaves, which they attack during the summer, a thallus very
closely resembling in many respects the sclerotia of Sclerotinia Fuckeliana, and
primordia of sporogenous receptacles are formed at the expense of the reserve-material
in the interior of the thallus after it has passed the winter on a dead leaf; examples
of these will be described in greater detail in Division IT.

Literature of mycelia.

Filamentous mycelia, haustoria, &c. See the lists of authors under the several
genera and groups in Division II. °

Erisyphe :—

v. MOHL in Bot. Ztg. 1853, p. 585:
DE Bary, Beitr. zur Morph. u. Phys. d. Pilze III.

Mycelial strands. Xylostroma, &c. :—

ROSSMANN, Beitr. z. Kenntn. d. Phallus impudicus (Bot. Ztg. 1853, Nr. 11).

TULASNE, Fungi hypogaei, p.'2 (Fungor. Carpol. I, pp. 99, 120, &c.).

H. HOFFMANN in Bot. Ztg. 1856, p. 155.

PALISOT DE BEAUVOIS in Ann. du Mus. d’hist. nat. VIII (1806), p. 334.

DUTROCHET in Nouv. Ann. du Mus. d’hist. nat. III (1834), p. 59.

TURPIN in Mem. de l’Acad. d. Sc. XIV (1838).

(Turpin and Dutrochet both describe the development of Cantharellus Crucibulum,
Fr. from a reticulately branching mycelium.)

FRIES, Plantae homonemeae, p. 213.

LEVEILLE in Ann. d. sc. nat. ser. 2, XX, p. 247.

DE Bary, Ueber Anthina (Hedwigia I, p. 35) ;—Id. Beitr. z. Morph. u. Phys. d.
Pilze I (1864).

JUNGHUHN in Linnaea, 1830, p. 388.

R. HARTIG, Wichtige Krank. d. Waldbäume, Berlin, 1874, p. 46 ;—Id. Die Zerset-
zungserscheinungen d. Holzes, Berlin, 1878.

Rhizomorphae. (See also Streinz, Nomenclator. Bail, Tulasne, II, cc., Palisot de
Beauvois, /. c.) :—

EHRENBERG, De Mycetogenesi, /. ¢. p. 169.

ESCHWEILER, Commentatio de generis Rhizomorphae fructificatione, Elberfeld,
1822.

NEES v. ESENBECK in Nov. Act. Ac. Nat. Curios. XI, 654; XII, 875.

J. SCHMITZ, Ueber d. Bau &c. d. Rhizomorpha fragilis, Roth. (Linnaea, 1843, p. 478,
tt. 16, 17).

TULASNE, Fungi hypogaei, p. 187 ;—Id. Fungor. Carpol. I.

BAIL in Hedwigia I, 111, and Ueber Rhizomorpha und Hypoxylon i in Nov. Act. Ac,
Nat. Cur. Bd. 28 (1861).

LASCH, Bemerk. über Rhizomorpha (Hedwigia i; 113).

OTTH, Ueber d. Fructification d. Rhizomorpha (Mittheilungen d. Naturf. Ges. Bern,
1856).

v. CESATI, in Rabenh. Herb. Mycol. Nr. 1931.

CASPARY, Bemerk. über Rhizomorphen (Bot. Ztg. 1856, p. 897).

FUCKEL in Bot. Ztg. 1870, p. 107.

R. HARTIG, Wichtige Krankh. d. Waldbäume, 1874.

BREFELD, Unters, über Schimmelpilze III, 136.

44 DIVISION I.—GENERAL MORPHOLOGY.

Sclerotia :—

DE CANDOLLE in Mem. Mus. d’hist. nat. II, 420.

LEvEILLE, Mem. sur le genre Sclerotium (Ann. sc. nat. ser. 2, XX).

Corpa, Icon. fung. ITI.

TULASNE, Mem. sur l’Ergot des Glumacees (Ann. sc. nat. ser. 3, XX, 1853).
KuHn, Krankh. d. Culturgewächse, p. 113, t. V.

(A list of the many treatises on the sclerotium of Claviceps = Secale cornutum
or ergot, will be found in Tulasne, ]. c. and in Handbooks of Pharmacognosy ;
earlier ones in Wiggers, Dissert. in Secale cornutum, Göttingen, 1831.)

TULASNE in Ann. d. sc. nat. ser. 4, XIII (1860), p. 12 ;—Id. Select. Fungor. Carp.
Cap. VIII.

BERKELEY, Crypt. Bot. p. 256.

BAIL, Sclerotium und Typhula (Hedwigia I, 93).

v. CESATI, Note sur la véritable nat. des Sclerotium (Bot. Ztg. 1853, p. 73).

COEMANS, Rech. sur la genése et les métamorphoses de la Peziza Sclerotiorum (Lib.
Bull. Acad. Belg. sér. 2, IX, Nr. 1).

WESTENDORP in Lib. Bull. Acad. Belg. VII, p. 80.

MUNTER in Lib. Bull. Acad. Belg. XI, Nr. 2.

FUCKEL in Bot. Ztg. 1861 ;—Id. Enumeratio Fungor. Nassoviae I (1861), p. 100.
(Typhula, lapsu calami Claviceps Euphorbiae.)

KUHN in Mittheil. d. Landw. Instituts, Halle I, 1838.

HOFFMANN, Icon. anal. Fungor. Heft 3.

E. REHM, Peziza ciborioides (Diss. Gottingen, 1872).

W. TICHOMIROFF, Peziza Kauffmanniana (Bull. Soc. Nat. de Moscou, 1868, p. 294,
Tables 1-4).

ERIKSON, in Kongl. Landsbr. Akad. Handl. Tidskr. 1879 (Typhula graminum), 1880
(Peziza ciborioides).

BREFELD, Bot. Unters. ii. Schimmelpilze III (Coprinus), IV (Peziza, Typhula).

SCHROTER, Weisse Heidelbeeren (Peziza baccarum) (Hedwigia, 1879).

EIDAM, Botrytis-Sclerotien (Ber. d. Schles. Ges. Nov. 1877).

CATTANEO, Sulla Sclerotium Oryzae (Arch. del Laborat. Crittog. di Pavia, 1877).

SCHROTER in Cohn’s Beitr. Bd. II (Tulostoma).

E. C. HANSEN, Fungi fimicoli Danici (Vedensk. Meddelelser af naturhist. Forening.
Kjobnhavn, 1876).

GASPARRINI, Ricerche sulla natura della pietra fungaja e sul fungo che vi sopran-
nasce, Napoli, 1841.

On the same subject: Treviranus in Vers. d. Naturforsch. in Bremen ;—Id. in
Flora, 1845, 17.—Berkeley, Crypt. Bot. 288.—Tulasne, /. c.

Mylitta and allied forms :—

OKEN in Isis, 1825.

LEVEILLE in Ann. d. sc. nat. ser. 2, XX, p. 247:

TULASNE, Fungi hypog. 197 ;—Id. in Sel. Fung. Carp. Z. ¢.

CoORDA, Icon. fung. VI, t. IX, 39.

BERKELEY, Crypt. Bot. 254, 288 in Gardener’s Chron. 1848, p. 829.

BERKELEY, CURREY, HANBURY in Proceedings of Linn. Soc. London, III (1858),
102, and Trans. Linn. Soc. Lond. XXIII, 91, t. IX, X.

H. GORE, Tuckahoe or Indian Bread, in Annual Report of Board of Rezents of
Smithsonian Instit. for 1881, Washington, 1883, p. 687.

Rosellinia quercina :—
R. HARTIG in Unters. a. d. Forstbot. Instit. z. München I (1880).

CHAPTER II.—DIFFERENTIATION OF THE THALLUS.—SPOROPHORES. 45

3. SPOROPHORES.

Section X. The sporophores! (Fruchtträger) are branches of the thallus of
peculiar form which spring from the mycelium and produce and bear the organs of
reproduction. The term organs of reproduction designates the germs of new in-
dividuals; by,indinidual we understand the dron as Häckel uses the word, and the
mother-cells which immediately produce them. These organs are distinguished
a.cordirg to the particular case by different names, spores, gonidia, basidia, asci,
&z., and the structures that bear them may have corresponding names, as gonidio-
phores, &c. Asa Fungus may have more than one kind of organ of reproduction,
as will be shown in the sequel, more than one of the special forms just named may
appear on the same species.

It has been already intimated that the sporophores have been compared with the
flowers or inflorescences of phanerogams, because their development usually closes, as
in the phanerogams, with the formation of a number of organs of reproduction, by
which their growth is limited either absolutely or for atime. This limited growth is
accompanied by a form and structure more sharply and characteristically differen-
tiated than that of most mycelia, and in many cases by a comparatively large develop-
ment. The sporophores therefore are not only the most characteristically constructed
part of the plant, but also the most striking on account of their form and size; hence
they used often to be taken for the whole plant, and are also at the present time the
chief subject of description in botanical works.

It follows from what has now been said, that we have to distinguish in the
sporophore generally between the points of origin of the organs of reproduction them-
selves and the other parts of the structure which may serve them as supports or
envelopes or the like, and which in each case bear some conventional name. These
parts are almost always raised above the substratum, and are firmly attached io it
and fed from it through the mycelium. The mycelium sometimes, not always, has
filiform or hair-like organs of attachment, rfzzords, in the shape of branches of the
hyphae which spring from the base of the sporophore and complete the provision for
its secure attachment and for the supply of nourishment, at least of that part of it
which it obtains from water. They have received the name of secondary mycelium from
their resemblance to the primary mycelium. It has not been ascertained in any in-
stance, whether under favourable conditions they are capable of assuming the normal
characters of a mycelium and producing sporophores; in many Fungi, for example,

1 [Compounds of the Greek word »apmös and such terms as ‘fruit’ and ‘fructification’ are
better used only for structures which have some direct connection with the sexual act; hence the
term ‘carpophore,’ the more exact translation of the German Fruchtträger, as well as the terms
‘fruit’ and ‘fructification,’ which under this limitation would not convey the sense of Fruchtträger in
this place, have been avoided and the more comprehensive expression ‘sporophore’ is introduced
here as its rendering. Berkeley’s specific use of ‘sporophore’ for what Léveillé had termed
“basidium ’ is no obstacle to the use of the word in the sense here indicated, as the term ‘ basidium’
is now a generally accepted one. The more recent application of the word ‘sporophore’ to
designate that stage in the life-history of a plant which is the product of an ovum and which as
a whole or in part is concerned with the formation of spores need be no objection to its use here;
the terms ‘sporocarp’ and ‘ sporophyte’ sufficiently denote different cases of that spore-producing
stage (see section XXXIII).]

46 DIVISION I.—GENERAL MORPHOLOGY.

species of Coprinus, Claviceps, Mucor stolonifer, and Syncephalis, this power does
not exist.

Sporophores may be divided, according to their structure, into two groups:
simple or filamentous sporophores (Fruchthyphen, Fruchtfäden), consisting of a single
hypha or of a branch of a hypha, and compound sporophores (Fruchtkörper) in the sense
assigned to the expression ‘compound’ in section I.

1. SIMPLE SPOROPHORES.

Section XI. Simple sporophores are branches of mycelial hyphae which
usually rise erect from them, and are themselves branched in a variety of modes
characteristic of the different species. When the hypha or its branch has grown to
a length which has a fixed average in each species, seldom, as for example in the
larger Mucorineae and Saprolegnieae, exceeding a few millimetres, the organs of
reproduction, spore-mother-cells, spores, are produced at their extremities in forms
which also vary in the different species and groups of species. With the formation
of these organs the growth of the sporophore ceases in most cases at once and for
ever, as for instance in the sporangiophores of Mucor and in the gonidiophores of
Peronospora (section XXX VII).

In other cases, such as that of the successive abjunction of spores which will
be described in section XVI, the growth, that is the increase in size of the sporophore,
comes virtually to an end with the commencement of abjunction; but abjunction
may continue at the same spots for a considerable length of time if sufficient
nourishment is supplied. The gonidiophores of Penicillium, Eurotium, and Asper-
gillus are examples of this kind (see section XVI).

In a third series of cases the first terminal formation of spores takes place at the
extremity of the sporophore after its apical growth has ceased, and when this
formation is completed a fresh growth in length of the sporophore begins at or close
beneath it, and is soon stopped by a new formation of spores similar to the first one ;
and on one hypha or branch the same process may be again and again repeated.

The second case is described, as was said above, in greater detail in section XVI.
The first and the third may be illustrated by some examples in the present place,
though their consideration will also be resumed in later sections. .

The thick tubular aseptate simple sporophores of the different species of Sapro-
legnia abjoint their extremity, which is club-shaped and filled with protoplasm, by
a transverse septum to form a spore-mother-cell (sporangium), in which numerous
spores are formed by division of its protoplasm (section XVIII). The spores escape when
ripe by an opening at the apex of the sporangium, which elsewhere remains entire.
This is all that happens in weakly specimens, which therefore represent our first case.
In strong specimens on the other hand which have been duly fed, the transverse septum
beneath the empty sporangium becomes convex outwards and projects into the
sporangium, and assumes the character of a new tubular point, which grows on into
the empty sporangium and often through the opening at its apex into the
free space beyond, and finally transforms its terminal portion into a new sporangium.
This process may be repeated several times on the same sporangiophore, so that
several successive sporangia are nested within one another. :

The allied genus Achlya differs partly from Saprolegnia in developing one or two
opposite lateral branches close beneath the empty sporangium, which themselves

CHAP, II.—DIFFERENTIATION OF THE THALLUS.—SIMPLE SPOROPHORES. 47

put out branches bearing new sporangia. There is here therefore a cymose branching
of the sporangiophores.

The gonidiophores in Peronospora, which are also without transverse septation,
are repeatedly forked or monopodially paniculate. The branches are all at first
narrowly conical, and when their longitudinal growth is completed their terminal
portions swell into an ovoid form, as.is seen in Fig. 20a, and are abjointed to form
gonidia, and with this the de-

velopment of a gonidiophore
of Peronospora comes to an
end. But in the nearly allied
genus Phytophthora after

the abjunction of each goni- =.
dium the narrow end of the
branch which bore it swells
slightly immediately beneath
it, and elongating at the same
time pushes the gonidium so

a

much to one side that it pre- Fi
sently forms a right angle
with the pedicel. Then in P.
infestans the gonidiophore
swells at the point of attach- FIG. 20. Phytophthora infestans, extremity of two simple sporophores. a forma-

eqs u tion of the first gonidia on the tip of each branch. &two ripe gonidia on each branch,
ment of the gonidium Into @ with the beginning of the formation of a third. Magn. about 200 times.
small narrowly flask-shaped
vesicle, and its upper end elongates at the same time and again assumes the character
of a gonidia-forming point. After a time a gonidium is formed on it in the manner
described above, and the process is repeated usually three or four times on the same
gonidiophore, or as many as twelve or fourteen times in luxuriant plants. Older simple
gonodiophores therefore, when examined dry, are

seen to bear a number of lateral nearly equidistant Ge

gonidia forming a right-angle with the gonidiophore,
and each standing on a flask-shaped swelling
(Fig. 202). As the ripe gonidia fall off instantly
in water, preparations treated with water have the
older branches of the gonidiophore swollen at inter- 4
vals into the shape of a flask with a single unripe
gonidium at most at its apex. ; a b c
The simple sporophores of Haplotrichum,
Gonatobotrys, and Arthrobotrys (Fig. 21) are |
short erect rows of cylindrical cells usually simple,
but sometimes with single branches. The apex of z
the uppermost cell swells up considerably in Haplo-
trichum, slightly in the other species, and puts out
numerous crowded protuberances, which together ges
form a small spherical head and develope into ——
gonidia. This is the whole of the development in : ;
Haplotrichum. But in the other two forms the ee
apex of the gonidiophore begins to lengthen again A neue ad Eon. bascond head
after the first head is matured and grows through of five successive heads. After Fresenius (Beitr).
it, and thus the head becomes a whorl surrounding me
the flanks of the gonidiophore; the growing end
of the gonidiophore attains to about the length of one of its lower segments, be-
comes septate above the first head and then forms a new head at its extremity like
the first. This proceeding may be repeated several times, till the gonidiophore is at

48 DIVISION I.—GENERAL MORPHOLOGY.

length occupied by several whorls of spores at a cell-length’s distance from one
another, or shows their points of attachment when the spores themselves have
dropped’.

The gonidiophores of Sclerotinia Fuckeliana, known by the name of Botrytis cinerea,
send out several lateral branches in a paniculate manner beneath their apex, the lower
of which are themselves branched. The somewhat enlarged and rounded ends of the
primary hyphae and of its branches abjoint many spores simultaneously on their
surface. As these ripen the sporiferous terminal cells of the hypha as well
the entire lateral branches die, dry up, and almost disappear, while the spores are
clustered together without arrangement. But a new growth begins in the cell beneath
the terminal cell ; it either simply elongates, and then forms a new sporiferous structure,
or it sends out one or more strong lateral branches which behave in the same way
as the primary hypha. Formation of sporiferous structures and prolification may
take place repeatedly on the same hypha; traces of the branches that have been
cast off are seen in the circular scars which project a little towards the outside’.

2. COMPOUND SPOROPHORES.

Section XII. The chief forms of the compound sporophores of the Fungi are
well-known to every one; the stalked umbrella-like and the sessile flabelliform or
horse-shoe-shaped ?zleus of the Hymenomycetes (Champignon, Mushroom, Amadou-
fungus), the club-shaped or shrubby Clavarieae, the Zeridia of the Bovistae and
Truffles, the cups of Peziza, and lastly the simpler forms which issue as flat or
pulvinate bodies from the surface of dead or living plants and are comprised under
the terms /ayer, stromata, or receplacula.

Some of the last more simple forms may be regarded as transitions to simple
sporophores, being indeed aggregates of these and exhibiting a more or less compact and
characteristic union, which may however vary in one and the same species. Such
are the gonidial layers of Cystopus and Hypochnus centrifugus, Tul. The gonidiophores
of Penicillium are sometimes single hyphae, sometimes are united together into tufts
to which Link gave the name of Coremium; and the same is the case with the
gonidiophores of the insect-killing Sphaeriaceae, in which the club-shaped branching
tufts, which are often of considerable size, are known by the name of Isaria’,

But by far the largest number of compound sporophores, and it is with these
that we are chiefly concerned here, show much more constant and more distinct
differentiations. Amid the great diversity of individual peculiarities one character
may be regarded as almost universal, namely, that a compound sporophore produces
its characteristic organs of reproduction (spore-mother-cells) in large quantities, and
that they are grouped in a definite manner and at definite spots upon it. The
spore-mother-cells form there continuous strata or aggregates of some other
shape, either by themselves or accompanied by accessory organs usually termed
paraphyses. These aggregates are conveniently included under the general name of

1 Fresenius, Beitr. t. III, V.—Corda, Prachtflora.—Coemans, Spicilége, No. 8.—Woronin,
Beitr. III, t. VI.

2 Fresenius, Beitr. t. II.

* Bot. Ztg. 1867, 1.

CHAP, II,— DIFFERENTIATION OF THALLUS. —COMPOUND SPOROPHORES. 49

hymenium or sporogenous layer, and are thus distinguished from the rest of the
sporophore. At the same time descriptive mycology, following convenience and
tradition, is in the habit of employing special appellations for the hymenia of the
several orders and reserving the word hymenium for the Hymenomycetes.

The structure of the hymenia will be described in later chapters. Many points
also in the structures and especially in the development of the sporophores, in the
narrower sense of the word, must be reserved for future consideration, partly because
a comparative examination of their first inception presupposes a previous discussion of
sexual relationships, partly because we have frequently to deal with facts which are
characteristic of single divisions, and which it will be more convenient to discuss when
we are engaged with these in Division II. Meanwhile it may be well to notice here
a few phenomena of very general occurrence.

It is only in certain cases that a compound sporophore begins as a terminal
or intercalary portion of a single hypha, which portion then developes into its
ultimate form by successive cell-divisions in every direction and by further differ-
entiations and growth in definite directions, somewhat after the manner of the anther
of a Phanerogam, if such a comparison is admissible. Some pycnidia among the
Pyrenomycetes (see Division II) show this exceptional behaviour.

The general rule here, as in the development of sclerotia and mycelial strands,
is that the sporophore proceeds from the union of branches of the hyphae, and grows
by the elongation and branching of these according to a general plan and in directions
determined by the species, and that new hyphal branches are introduced between
those previously formed in agreement with the original design. This earliest stage,
which may be called the meristematic stage, and in which new segments and new
hyphal branches are added, is succeeded in every section of the sporophore by a
stage of increase of volume of the existing elements and of their permanent differentia-
tion, the amount of which is very different in different cases, and reaches its highest
point in the Gastromycetes and especially in the Phalloideae.

The hyphal branches which form the compound sporophore originate in some
cases in a single branch of the mycelium, which may have the morphological
significance of an archicarp or homologue of a female sexual organ with its immediate
supporting structure, as in Eurotium, or have no sexual relationship, as was pointed out
above in the sclerotia of Coprinus and Typhula variabilis, and in the sporophores of
some species of Coprinus which were shown by Brefeld especially to be produced
without the intervention of sclerotia.

In the majority of better-known cases the formation of the compound sporophores
begins with the union of two or several or many hyphal branches of different origin.
This is the case with some of the sporocarps of the Ascomycetes which will be described
at length in Division II, with the very simple hymeniophore of Exoascus Pruni, with
most of the compound sporophores mentioned above as growing from sclerotia (the
various species of Peziza, Claviceps, Typhula gyrans, &c.), and the compound sporo-
phores of Agaricus melleus whichhave their origin, according to Hartig*, in the mycelial
strands in the same way as the ordinary mycelial branches. Most of the, Hymeno-
mycetes which are not fleshy might be added to the list, inasmuch as their compound

1 1c. above, p. 28.

[4] E

50 DIVISION I.—GENERAL MORPHOLOGY.

sporophores, as far as they have been observed’, always begin their development as
comparatively large compact tufts of hyphae springing from the mycelium, and we
may even venture to assume that the great majority of compound sporophores take
their origin, as here described, from many hyphae. At the same time it must be
acknowledged that it has been found possible to follow them back to their very first
beginning with perfect certainty only in the few cases which have been noticed
above.

Many inconspicuous compound sporophores, such as the gonidiophores of Uredi-
neae and the stromata of many small Pyrenomycetes, remain as it were in the stage
of the tufts of hyphae and pass into their ultimate form without further remarkable phe-
nomena ofgrowth. But where a larger structure is produced, the course of development,
amid great variety of detail, discloses two chief types, which closely resemble the two
types of growth above described, for the mycelial strands on the one hand and for the
sclerotia on the other. In the one type, asin the formation of sclerotia, the growth
is nearly uniform for a long time in all parts of the structure; then comes the second
chief stage, the ultimate development by internal differentiation. The compound
sporophores of the Gastromycetes show this mode of proceeding in the most marked
manner. In the other type the general course is progressive, just as it is in the
mycelial strands or in the single hyphae, advancing in the direction of fixed spots in
the surface, which are themselves pioneers in the advancing growth and maintain it by
formation of new cells; as any section becomes removed from these spots growth in
it ceases, and its component elements assume their definitive character. According
to the form of the whole structure and of the superficial portion ofit in which
progressive growth occurs, this growth may be said to advance towards the apex, to
be apical (acropetal), or to be marginal, and the peripheral progressively growing
spots by another usage may be termed growing points or margins ; or growth is
progressive towards the whole of the free surface of the structure which bears the
hymenium, as in the horse-shoe-shaped pilei of Polypori which are several
years old, and in other Hymenomycetes also with various modifications and
limitations.

Growth thus on the whole progressive does not preclude intercalary areas of new
formation and extension from making their appearance between portions in which
these processes had ceased; but the actual occurrence of these areas has never been
distinctly proved in any of the cases which belong strictly to this type.

On the other hand, the combination of the two types of growth has been
ascertained in a considerable number of species. We find, for instance, internal
differentiation and subsequent progressive growth in the compound sporophore which
is the chief product of Amanita. The young stipe of the Coprineae® has a transverse
intercalary zone in the part just below the apex, in which there is continued formation
of new cells by (meristematic) division ; the velum also has intercalary growth, but
all the growth of the pileus and the final elongation of the stipe is progressive. In
the Xylarieae, Cordyceps, &c. the growth of the club-shaped sporophore is progressive

1 Hartig, Zersetzungserscheinungen d. Holzes, p. 21 (Polyporus annosus), p. 32 (Trametes Pini),
p. 41 (Polyporus fulvus), p. 50 (P. mollis), p. 98 (Hydnum diversidens), &c.

2 Goebel in Arbeiten d. Bot. Instit. zu Würzburg, II, 354.

® Brefeld, Schimmelpilze, IIT.

CHAP. II.—-DIFFERENTIATION OF THALLUS.—COMPOUND SPOROPHORES. 51

(acropetal), and the perithecia are subsequently formed in them by internal differentia-
tion ; other instances might be given.

Some compound sporophores with acropetal growth are normally and often
uniformly branched, as in many Clavarieae, the Xylarieae, and Thamnomyces. The
ramifications appear always to arise as bifurcations of the growing points, but this has
not yet been sufficiently investigated. Inquiry is also needed in the cases of
supposed monopodial and always slightly irregular branching seen in Agaricus
racemosus, Isaria brachiata, and some others. Peziza Sclerotiorum often has
irregulary disposed exogenous branches on the stalk-like portion of a compound
sporophore, especially on the part near the ground. We are not concerned here with
branching which is purely adventitious, artificially excited, or monstrous.

The duration of growth under normal and favourable conditions differs much in
different species. In the small delicate fleshy Coprini the whole process, from the
commencement to full ripeness and decay, may be completed, according to Brefeld, in
8-10 days, while the solid woody Polyporeae maintain a progressive growth for
years; Trametes Pini, for example, according to Hartig for 50-60 years. There
are all possible intermediate cases between the two extremes. Long-lived species
necessarily advance and remain stationary periodically with the change of the seasons.

Apart from this latter influence, the course of growth under uniformly favourable
conditions is marked by the same order in the Fungi as in the higher plants. First
there is the laying down of new parts by formation through division of meristem of new
tissue-elements accompanied by a small increase in volume; then the differentiation of
the tissues takes place, and lastly the final elongation and increase of volume. The first
two operations are performed slowly and steadily at least relatively to the third, the
one passes gradually into the other; and the transition to the third stage is also
gradual in the forms which are not fleshy, such as the Xylarieae and the leathery and
woody Hymenomycetes. But in the forms with fleshy succulent substance, especially
the Hymenomycetes and Phalloideae, the transition to the third stage is often abrupt,
and this stage itself is traversed with relative and absolute rapidity. Of the 8-ı0 days
occupied by the growth of the small Coprineae mentioned above the last tenth at
most was devoted to the final elongation and expansion, the former stages requiring
7-9 of the 8-10 days. In the case of many other fleshy Hymenomycetes, such as
Amanita, the time necessary for the first two stages is much longer than this, and
Schäffer is not much beyond the mark in estimating it at a year in Phallus impudicus *;
but more exact determinations are desirable. But the final elongation and expansion
are accomplished in all these cases, under favourable circumstances, in a few days at
most. The proverbial rapidity with which the succulent Fungi shoot up from the
ground, as is the case with the green vegetation in spring, is chiefly due to
the abruptness of the final extension of the structure which has long been in existence
and slowly and gradually developed.

It has in no case been shown with perfect certainty that the peripheral
extremities of the hyphae, which take the lead in progressive growth, remain the
same during the whole process, and that the compound sporophore therefore is built
up-of the united branches of a constant number of monopodially branched primary

1 Der Gichtschwamm mit dem griinschleimigen Hute, Regensburg, 1760, p. 7.
E 2

52 DIVISION I.—GENERAL MORPHOLOGY,

hyphae destined from the first for the particular structure. In small compound
sporophores with an apex which continues narrow, being composed of only a few
hyphae, like those of Typhula to be noticed presently, it may, though it need not
necessarily, be assumed that such is the case. In the much more frequent cases in
which the advancing apex or margin becomes constantly broader with uniform
thickness and separation of its elements, new hyphal branches must be introduced
one after another between the original ones, or take the place of them in sympodial
succession. In long-lived species with periodical cessation of growth in the cold or dry
season most of the extremities of the branches must die away, and be replaced when
growth begins again by branches of deeper origin which thrust themselves between
them. The position of the dead extremities or the portions of new growth limited by
them may then be seen as zones in the older structure.

The consideration of special phenomena of development is deferred to a later
page for the reasons assigned above. But it will be well to give a more detailed
description in this place of some examples at least of progressively growing compound
sporophores, because this mode of growth is very general both in the different
divisions of the Fungi and in sporophores of very different morphological value.
The examples are for the most part those of the first edition of this book.

1. The stalk-like compound sporophores of Typhulae which form sclerotia,
Typhula variabilis especially, begin on the sclerotium as the bundle of firmly united
parallel hyphae with their extremities curving dome-like towards each other, which
was noticed above on page 38. The compound sporophore increases in length. The
united extremities of the hyphae in the dome-shaped apex continue all the while
very delicate and full of protoplasm, and comparatively small-celled. As the
segments of the hyphae are further removed from the apex of the growing sporophore
they increase steadily over a certain distance in length, breadth, and thickness, and
the whole structure increases in compactness and firmness ; no further augmentation
takes place at its base. From these facts it appears that the growth in length of
the sporophore, so far as it depends on formation of new cells, takes place at and
close beneath the apex by the apical growth of the united hyphae ; this is therefore
the growing point. Then the cells produced at the growing point elongate in the
order in which they are formed and assume their ultimate form. As the elongation
commences the primordia of scattered unicellular hairs make their appearance as
branches on the superficial hyphae of the lower sterile portion, and on the upper part
the dense weft of the hymenial layer. At length the activity of the growing point
ceases and with it the growth of the whole sporophore. In the interior of the
parts more remote from the growing point there appears to be no further formation,
or at any rate no considerable formation of new cells, either by division of previously
formed cells or by addition of new hyphal branches introduced between those already
in existence’.

z. The compound sporophores of Selerotinia Sclerotiorum (Fig. 22), the early
stages and special structure of which will be again described in Division II, burst forth
as cylindrical bodies from the sclerotium, grow in this form to a length of 1o mm.
more or less, and then increase in breadth at the apex in such a manner as to pass
through the shape of a club ‘into that of a stalked funnel-shaped cup, which may
finally have its margin turned outwards. The young cylinder consists chiefly of a bundle
of nearly parallel hyphae; the slender delicate-walled extremities of the hyphae

1 See also Brefeld, Schimmel pilze, III.—Reinke u. Berthold, Die Zersetzung d. Kartoffel durch
Pilze, p. 58.

CHAP, II.—DIFFERENTIATION OF THALLUS.—COMPOUND SPOROPHORES. 53

are in the apex of the structure and form its growing point, in which growth in length
continues, while it dies out in the parts below it as these become successively further
removed from it and the cells of the hyphae have grown longer and thicker. The parallel
arrangement of the hyphae is not everywhere maintained; firstly, a number of short
hyphal branches bend round obliquely upwards and outwards close below the apex,
and terminate in the free lateral surface, where they form a cortical layer to
the compound sporophore; and secondly, in the first stages of the develop-
ment, when the sporophore is scarcely visible to the naked eye, the hyphae surrounding
the longitudinal axis are somewhat more loosely united
together than in the periphery and have their extremi-
ties slightly curved towards the axis. In this state
the primordial sporophore grows to a certain length by
continued apical growth in a straight line. Then the
growth in length of the axile hyphae is retarded while
that of the peripheral hyphae advances rapidly. In
this way a narrow canal, which can only be seen
under the microscope, is formed in the apex of the
cylindrical sporophore with its upper margin bounded
by the slightly incurved extremities of the hyphae.
And while growth constantly proceeds in the direc-
tion of this margin, successive formations of new and gy, 2. Pestca (Sclerotinia, Fuckel)
similar elements take place in it, and behind it in- Scleretiorum. Lib. Sclerotium with emerg-
tercalary additions (which however gradually cease u en

to appear), together with the first formation and

development of the hymenium and other parts: thus the cylindrical body gradually
assumes the form of the stalked funnel. The final growth in thickness of the stipe,
which is however only slight, occurs chiefly in the periphery, and as the axile hyphae
share but little in it, a narrow canal is formed which traverses its length.

In other species of stalked Peziza, P. nivea for instance, I have not myself observed
the first stages in the formation of the cups; they are not however difficult of obser-
vation, and several accounts have been given of the way in which they grow for
a time by formation of new elements in their originally involute margin, and
at length assume their final form
by an expansion of their tissue-
elements advancing in the direction
of the margin.

3. The sporophore of Stereum
hirsutum (Fig. 23), which is de-
scribed as a pileus divided in half
without a stalk and laterally ate
tached, is generally an irregularly

roundish flat disk, the larger part FIG. 23. Stereum hirsutum, Fr. Vertical radial section through the
of which stands out at right angles margin of a fresh pileus slightly magnified and giving a partly

. matic representation of the course of the hyphae; / the advancing
from the substratum, whilethe other margin with two zones behind it, % the hymenial layer, » medulla,
and often very small part is firmly ind. x covering of hairs.
fastened to it; if the substratum
is vertical, the projecting part of the Fungus has a horizontal direction, its upper
surface is thickly covered with hairs, and on its under surface is the hymenium. We
need not here take notice of other and more irregular forms which are of frequent
occurrence.

The sporophores first appear in the form of semicircular gray tufts of hyphae
1-2 mm. in breadth. These are formed on stout mycelial filaments which spread
in large numbers through the dead wood inhabited by the Fungus. The tufts are
formed of numerous hyphae, which spread from a central point with tolerable regularity

54 DIVISION 1.—GENERAL MORPHOLOGY.

like the spokes of a wheel. They are closely interwoven at the centre, but separated
towards the circumference by constantly increasing interspaces, and thus the surface
is covered with spreading hairs. These appear under the microscope to be colourless
or of a uniform brownish colour, while the hyphae of the central tissue is coloured by
granules of a reddish-yellow pigment. As the development proceeds the lower half
of the hemispherical body, lower that is in relation to the substratum which is
supposed to be vertical, takes a reddish-yellow tint and its surface becomes smooth
and velvety. Thin radial sections following the direction of the hyphae show that,
as far as the last-mentioned character extends, numerous hyphae, most of which
contain reddish-yellow pigment-granules, have grown from the central weft to
the surface and have thrust themselves in large numbers everywhere between
the previously formed hairs and enclosed them. The upper half of the hemispherical
compound sporophore retains its original character. Now begins a vigorous longi-
tudinal and apical growth of the hyphae which run into the margin of the reddish-
yellow under surface of the young pileus, while those which terminate in its middle
portions elongate but little or not at all. Hence the upper surface becomes concave
and the horizontal portion of the pileus raises itself from the substratum,
while the growth of the hyphae advances at its margin. Sections show that
the margin consists of a massive and compact layer of truncated rather thick
hyphal extremities, which incline slightly towards the under surface and usually contain
reddish-yellow pigment-granules. These extremities join on to the perfect hyphae of the
pileus close to the point of origin of the latter ; these perfect hyphae being distinguished
from them by their pellucid contents, but not by greater thickness, and running in
radiating lines parallel to the surface of the pileus. The differentiation of the tissue
of the pileus begins close behind the advancing margin, and results in a lower colourless
medullary stratum, and an upper thin rind-stratum distinguished by membranes
of a clear brown colour. Numerous hairs begin to be developed on the upper surface
nearer the margin, and the hymenium on the lower surface. The former are simple
stout hyphal branches which either spread or are curved backwards; the outermost
of them project beyond and mostly cover the growing margin. Numerous branches
run obliquely and with a slight curve close behind the margin towards the hymenial
surface. The nearer the base of the pileus, the more numerous are the hymenial
elements which are introduced between those previously formed, and the more
decidedly do they assume the vertical position as regards the surface of the original
constituents of the hymenium. The portion of the pileus which is attached to the
substratum shows essentially the same mode of growth as that which projects from
it, only the hairs on its outer surface penetrate as rhizoids into the substratum.
Measurements by J. Schmitz and microscopic examination show that the enlargement
of the pileus takes place only next the margin’.

4. The unveiled umbrella-shaped pileus with central stalk of the Agariei (Fig. 24)
appears at first on the mycelium as a small cylindrical, ovoid, or even spherical body,
pointed at the upper end and consisting throughout of very delicate firmly united
hyphae running’ longitudinally. At a very early stage, when the entire structure
in the specimens which I have examined is 3-2 mm. in length, the extremities of
the hyphae at the upper end spread in every direction as they grow and at the same
time branch copiously. This gives rise to a small hemispherical head separated
from the lower portion by a shallow annular furrow, the primordium of the pileus
(Fig. 24a). A vigorous growth then commences in the extremities of the hyphae
which form its margin, and they constantly elongate, but at the same time retain
their original thickness, and continue as closely woven together as at first ; there
must therefore be a constant introduction of new branches between the earlier
ones in the direction of the surface of the pileus. The hyphae which run towards

1 See also R. Hartig, Zersetzungserscheinungen d. Holzes, p. 130, t. XVIII.

-CHAP. II.—DIFFERENTIATION OF THALLUS.—COMPOUND SPOROPHORES. 55

“
the apex of the pileus soon cease to lengthen; they become the tissue of the middle
of the pileus, while as the margin advances the hyphae which run into it send out
numerous straight or curved branches upwards and outwards, which in their turn
soon cease to elongate and form the general tissue of the pileus (Fig. 24 4). Closely
crowded branches from the under surface of the layer which runs into the margin
grow at the same time and in the same centrifugal succession from a curved base
perpendicular to the under surface of the pileus; these are the beginnings of the
tissue that bears the hymenium and of the hymenium itself. They are at first of
uniform length, and the surface of the hymenium is smooth at first, as Hoffmann
rightly affirms in opposition to a former incorrect statement of mine, though it only
continues so for a short time. The elongation of the hymenial hyphae which
grow vertically downwards takes place in alternating radial bands in varying degree.
In some it continues longer, and they project beyond the smooth surface as the trama
of the lamellae, on which the hymenial elements arise in the position already described,
advancing from the base toward the free edge. The hyphal extremities cease to
elongate at an earlier period in the intervals between the lamellae, and become
directly elements of the hymenium.

During this growth by terminal and marginal formation of new constituents, the
parts at a distance from
the growing point or mar-
gin enlarge by expansion
of their cells, and the tis-
sue which is at first uni-
form is differentiated at
the same time into the
several layers of the ma-
ture sporophore. It is
readily observed that this
process of expansion also
advances in the stipe from
below upwards, and in
the pileus from the centre
to the margin. To this ex-

pansion of the originally FiG. 24. Agaricus (Collybia) dryophilus, Bull. Radial longitudinal section showing
very small elements to the course of the hyphae. @ a quite young and entire specimen 1°3 mm. in height; first

beginnings of the pileus. 4 older specimen with the pileus 2°5 mm. in breadth; ¢ piece

several times their former of 2 lamella Slightly magnified.

size is due in great part,

especially in rapidly growing fleshy sporophores, that enlargement which may be seen
with the naked eye. In Agaricus (Mycena) vulgaris for instance I succeeded in deter-
mining, by measurement of the cells and counting their number on the transverse
section, that the increase in length and breadth of the stipe, which becomes on an
average 50-60 mm. long, from the time when its length was about 3 mm. and its
cells could be exactly measured, must be almost exclusively due to extension of
the cells. I obtained the same result in the case of Nyctalis parasitica ; the conclusion
was similar in the case of Agaricus (Collybia) dryophilus, Bull., but less precise
on account of the very unequal length of cells placed at the same height. Exact
measurements can scarcely be made in the pileus owing to the curvatures and
want of uniformity in the cells, but here too it is evident that there is an expansion
of the tissue-elements, which often exerts considerable force and advances towards
the margin. It appears to me to be doubtful whether there is also any formation
.of new cells by transverse division of the primary cells of the hyphae and by pro-
duction of new branches in parts removed from the margin. It does not take place in
either of the two cases just mentioned, but they are too isolated to allow of our
drawing a general conclusion from them. Branches often occur on hyphae which

6 DIVISION I.—GENERAL MORPHOLOGY,

are much expanded or are in the act of expanding, which are little if at all
thicker than the primary hyphae and are rich in protoplasm, and therefore look
as though they were of recent formation. Whether they are really new branches,
or only branches formed at an early period but not sharing in the expansion,
must remain undecided. In the hymenium certainly new elements are introduced
between the earlier ones usually for some time after its first formation.

A distinct efinasty prevails at first in the general growth of the pileus; the
parts belonging to the upper side grow more vigorously than those of the lower,
and according to the position and breadth of the annular zone which is most strongly
epinastic, either the margin of the pileus is rolled inwards or the whole of the
under or hymenial surface approaches or even touches the stipe; or both effects
are produced, and this is most frequently the case. Subsequently, when growth is
coming to an end, the epinasty changes to Aydonasty, the under side grows more
strongly than the upper, and the entire pileus expands with more or less rapidity
in each separate case from its original bell-like or conical form into that of an
umbrella, while the incurved margin may even become curved upwards and outwards.

We cannot enter here into the variations which occur inthe development and form of
the pileus in the several groups and species, and indeed we possess a very limited
number of exact observations on them. The account which has just been given is
founded on my own examination of Agaricus (Mycena) vulgaris, Pers., A. (Collybia)
dryophilus, Bull, and Nyctalis parasitica, Fr., on the study of the history of
development of Agaricus (Clytocybe) cyathiformis and Cantharellus infundibuli-
formis in conjunction with Woronin, and on the works of H. Hoffmann. Hoffmann
indeed makes the hyphae of the middle of the pileus in the section Mycena not
run radially towards the surface and there terminate, but parallel to the surface
of the pileus (for so I understand his expression ‘ horizontal’); and in this small point
our otherwise conformable accounts differ. It is possible that different species vary in
this respect. The course of the hyphae can be readily seen to be as I have stated it in
Agaricus vulgaris, when the pileus is still young, but not in the older states ; then the
whole of the superficial tissue of the pileus assumes the character of a tough gelatinous
felt, which may be removed as a coherent membrane from the pileus, and in which the
hyphae have no particular arrangement.

In most of the sporophores of which we are here speaking, especially those of a
fleshy consistence, growth proceeds without interruption and soon reaches its ter-
mination; it may go on more slowly or be arrested for a time, if the conditions are
unfavourable, and afterwards recommence ; more serious injuries, especially persistent
drought and cold, stop it altogether. The power of withstanding such unfavourable
influences varies much in the different species. On the other hand, as has been
already stated, the pileus in many leathery and woody forms, such as the Xylarieae
and especially the Hymenomycetes, has the power of recommencing suspehded growth
with the return of favourable conditions. During each stationary period in the
Hymenomycetes the hyphal extremities in the margin and upper surface of the
sporophore, which for the most part die off, assume in many cases another colour and
usually a darker one than that of the rest of the tissue, which is seen therefore
in sections to be divided by dark lines into the zones already mentioned (Fig. 23).
The tissue of the sterile surface also has often a different colour at the beginning
from that which it has at the end of a period of growth ; and at the commencement of the
period of growth it often swells suddenly into a cushion, which runs quite round the margin
of the pileus and flattens out again towards the margin with the continuation of growth.
The periods of rest and growth are thus here as elsewhere indicated on the sterile
surface of the Fungus, as in some other plants, by zones concentric with the
margin of the pileus, and usually answer exactly to the interior zones but are sometimes
less distinctly marked. It is scarcely necessary to mention examples of these ‘ pilei
zonati,’ since they occur in many of the most common and best-known species,

CHAP, II.— DIFFERENTIATION OF THALLUS.—COMPOUND SPOROPHORES. 57

such as Stereum hirsutum, Polyporus zonatus, P. igniarius, P. fomentarius, P. Lenzites
and their allies. The hymenial side in most of these Fungi increases in circumference
only as the margin of the pileus continually advances, but no increase in thickness
is thereby brought about.

On the other hand there is an addition to the free hymenial surface in every
period of growth in many species of Polyporus, especially in the Fomentarii of Fries,
in Polyporus fomentarius for example, P. igniarius and P. Ribis, and in Trametes Pini,
Corticium quercinum and allied forms. Sections therefore through older specimens
show zones on the hymenial side as well as in the rest of the tissue of the
pileus ; each zone answers to a zone in the substance of the pileus and is its con-
tinuation, the youngest hymenial zone being continued into the outermost marginal
zone of the pileus.

Persoon! and Fries? call the zones of these Polypori annual zones. They may
no doubt be correctly compared in certain points to the annual rings of Dicotyledons,
but it has never been distinctly proved that only one new zone is formed each year
in these plants. There is no doubt that many zones are formed in the course of a
year in most of the other zoned mushrooms. J. Schmitz has shown this in detail
for Stereum hirsutum, and there are a certain number of many-zoned pilei in the
Hymenomycetes which only last one year.

Section XIII. The structure of the mature compound sporophorss either
continues to be evidently hyphal, or it becomes pseudo-parenchymatous in the sense
of the word explained in section IV. When a compound sporophore is much
differentiated both kinds of structure may occur in different regions of it and in
different strata.

In the first case the course of the ramification of the hyphae may be quite
irregular and they may interlace in every direction, as in most sclerotia; this
happens in sporophores in which the growth is not peripherally progressive, and in the
small structures mentioned on page 51 in which this mode of growth is at least only
feebly developed, as in the Uredineae and in endophytic Ascomycetes (Rhytisma,
Polystigma, Epichloe). The pileus of Morchella and Helvetia may be mentioned
in this connection. But where the growth is distinctly progressive, whether apical or
marginal or towards the surface, the great mass of the hyphae usually follow a
course corresponding to these directions, and in large compound sporophores the
surface of sections or broken pieces may often appear fibrillate even to the naked eye.
The course of the hyphae in these cases either corresponds exactly with the form and
direction of growth of the parts, as for example in Stereum hirsutum (Fig. 23) and in
the stipes of the smaller Agarics, or the hyphae are sinuous and interwoven with a
larger or smaller number of ramifications spreading in the most different directions,
and forming what at first sight appears to be an entanglement of threads, such as we
see for example in the tissue of the pileus of many Agarics. But sections made in
the right directions will usually show that here the primary hyphae follow a course
which answers to the general rule. There are however some exceptions ; a striking
instance of the latter kind is found in Polyporus annosus°, which has persistent
progressive growth of the margin of the pileus and of the hymenial projections, yet,
except in the outermost margin of the latter, the course of the slender interwoven

1 Essbar. Schwämme, p. 17.
? Epicris. p. 463.
® R. Hartig, Zersetzungserscheinungen d. Holzes, p. 21.

58 DIVISION I.—GENERAL MORPHOLOGY.

hyphae and of their ramifications appears to be entirely without arrangement.
R. Hartig’s description of Polyporus fulvus should also be consulted’. -

Compound sporophores with distinct pseudo-parenchymatous structure ‚could
only be illustrated by a number of individual cases all differing in many points
from one another, but such an enumeration would be out of place here.

One feature common to most, if not all, compound sporophores of all types ot
structure is the more or less distinct separation of a peripheral layer from the inner tissue.
Compound sporophores with much internal differentiation, among the Gastromycetes
especially, exhibit many peculiarities in connection with this point, which will be
noticed again in later sections in describing individual cases. The separation in

\compound sporophores with progressive growth, and also in some small ones with only
slight differentiation, usually consists in the fact that an inner less compact and firm
mass, which may be termed the medulla or medullary mass, is surrounded in the parts
which do not directly bear the organs of reproduction, as in the sclerotia, by a
peripheral rind or cortical layer, in special cases termed also the pelicula or cutts,
which is the outer boundary of the whole structure. When the compound sporo-
phore forms organs of reproduction directly on its surface, the hymenial layer takes
the place of the cortical. Both the medulla and the rind may be separated again
into subordinate layers.

The rind is distinguished from the medulla either by the structure, size, and
firmness of union alone of its elements, their arrangement (the fibrillation) being similar
in both, or their arrangement also is different.

In the first case the rind is usually of a firmer texture than the medulla owing to
the less breadth and closer union of its elements. This is its character in very many
fleshy or cartilaginous Mushrooms, such as the larger Clavarieae, Calocera, many
Agaricineae and Pezizeae, and in the stroma of Rhytisma. The cells of the rind have
also not unfrequently coloured sclerosed walls, which are wantirig in those of the me-
dulla, as for instance in Peziza hemisphaerica, Rhytisma, Stereum hirsutum, &c. In
other forms the rind is distinguished from the medulla by gelatinous cell-walls, as in
the pileus and stipe of Agaricus (Mycena) vulgaris, in the pileus of Russula integra,
in Panus stypticus, and many other Agaricineae, the outer covering of which is a tough
gelatinous felt, while the interior tissue is not gelatinous. A different arrangement of the
elements of the rind from that of the medulla occurs frequently in compound sporophores
with hyphal structure; the hyphae of the medulla follow in their course the form of the
sporophore, but numerous curved branches with their convexity towards the apex pass
off from its hyphae in the direction of the surface, where they terminate in copious
ramifications and close union with one another. The extremities themselves either
form a tangled weft, as for instance in Auricularia mesenterica and species of Poly-
porus, or else they are placed perpendicularly to the surface, so that the rind appears to
be formed of palisade-like cells or cell-rows, as in Peziza Sclerotiorum, in the large-
celled tissue of the surface of the stipe of Helvella crispa and H. elastica, in the
outer and inner surface of the hollow stipe of H. esculenta and Guepinia contorta ?,
in the smooth surface of the pileus of Polyporus lucidus (Fig. 25), and in that of
P. fomentarius.

1 R. Hartig, Zersetzungserscheinungen d. Holzes, p. 40.
? Dacryomyces contortus, Rabenh. Herb. Mycol. Nr. 1984.

CHAPTER III.—SPORES OF FUNGI. 59

A very large majority of Fungi have spreading Aazrs on their surface, which
arise as branches from the hyphae of the compound sporophores and show this
origin even where its final structure is pseudo-parenchymatous. Some of them come
from the hyphae of the surface itself, some originate at a greater or less depth
beneath it and pass obliquely to the outside through
the layers of tissue that cover their point of origin. They A RINIGRRI AIT
are simple cells or cell-rows and branched or unbranched, Ahi I) | i
and scarcely yield to the hair-formations or the higher Ds

Rink

plants in variety of form, direction, size, colour, structure, N

and thickening of their membranes; the most varied series

of these formations is to be found in Peziza and the allied !
Ascomycetes, and in Erysiphe and Chaetomium.

In many cases the hairs are closely combined in tufts,
which appear to the naked eye according to the species as N \
bristles, scales, or warts, as for instance on the surface of
the pileus of Polyporus hirsutus and P. hispidus, Of iongituaisal Seton King tee Armee
Hydnum auriscalpium, Tremellodon gelatinosus, &c., or Mare ueumen » medulanyhyphas,
as cylindrical tufts expanding into the shape of a funnel .
at their extremity, such as are found on the sterile surface of the pileus of
Fistulina hepatica, and from their shape were once described as rudiments of the
tubuli of the hymenial surface’. Ifthe superficial felting of hair is very thick, it may
be a question whether it should not be considered to be a cortical layer, and the
determination must rest on what is suitable in each particular case.

Where the compound sporophore is very close to the substratum, single
hairs or tuf s of hairs often assume the character of rhzzozds.

Here would naturally be the place to speak of the Lichen-thallus and especially
of its fruticose and foliose heteromerous forms; but it will be more convenient to
reserve this part of the subject to Division III.

CHAPTER III. Spores oF FUNGI.

Section XIV. The propagation of the Fungi, in the widest sense of that word
which implies the production of new bions through a mother-individual, is generally
effected by the abjunction, and in most cases by the complete separation, of cells from
the maternal structure, which then develope into daughter-bions if the necessary
conditions are present. The single cell thus abjointed from the mother and capable
of this development into one or more than one bion we term here a spore;
empirically we fix that moment and condition of its development, in which
abjunction from the mother as its nutrient source is effected, as the moment
and condition of its ripeness or maturity; the commencement of the further develop-
ment of the ripe spore is its germination.

1 Fries, Syst. Mycol. I, 396.

60 DIVISION I.—GENERAL MORPHOLOGY.

It is a universal histological law that every spore is the daughter of one or some-
times more than one mother-cell, which is consequently called the spore-mother-cell.

There are many and great differences between spores and their mother-cells in
respect of their special qualities, structure, and mode of formation, and in respect of
their position in the life-history of the species and the homologies which result from it,
and several different kinds of spores may be formed in the course of development of a
single species. Hence there are several categories, kinds, or forms of spores and
spore-mother cells, that may be distinguished according to these different points of
view. In their terminology these distinctions are expressed sometimes by adjectives,
sometimes by compounds of the word spore, as swarm-spores, ascospores, &c., some-
times also by special words, gonrdium, ascus, basidium, and others. Each of these
terms signifies a spore or its mother-cell in the general meaning of the word above
indicated, with a definite specific reference. A fuller explanation of the terms and
an account of the reasons for their adoption are reserved for Chapter IV.

The distinction between spores and their mother-cells on the one hand and
vegetative cells on the other is naturally drawn first of all from cases in which the
differences are most distinctly marked, and these constitute the large majority. It is
to be expected that in a large and much graduated series of forms some would occur
in which those differences would be less marked, sometimes indeed be almost
obliterated. As examples of this may be mentioned the vegetative form described on
page 4 as Sprouting Fungus, in which each sprout may be quite rightly termed a spore
in the above acceptation of the word, and in the gemmae formed by the abjunction of
cells with the power of germination from the vegetative hyphae in the Mucorini,
Tremellineae, and Ascomycetes, which will be subsequently described. No confusion
would be caused by a consistent use of the word spore in these cases. Whether it
would be convenient that other terms should be introduced in its place is a matter to
be determined by judicious agreement in each case.

Many of the peculiar characters of spores and many of the phenomena attending
their formation and ripening recur in the most different groups of the Fungi, and
would necessarily be included in a general survey. Others again are confined to
individual groups and can only be fully discussed with them. At the same time we
shall, I believe, get a clearer view of the whole subject ifthe second series of characters
is considered along with the first, and those points only are reserved for special
description in Division II which are quite irreconcilable with such general treatment ;
among these are especially questions concerning homologies and sexual relations
which are still in many respects obscure and debatable and must be considered in
each individual case.

a

1. DEVELOPMENT AND SCATTERING OF SPORES.

Section XV. According to our present views on the origin of cells, every cell is
the daughter of a mother-cell, and except in the cases of conjugation and rejuvenescence
is formed by a process of division which takes place in the mother-cell?. Either all

" I pass over for the present the conjugation and coalescence of cells for reasons of convenience
which have been partly intimated above; this subject will be considered in Division II. Reju-
venescence I exclude because it is not the formation of a new cell, but only the transformation of a
previously existing cell.

CHAPTER III,—SPORES OF FUNGI. 61

the constituents of the mother-cell enclosed within its cell-wall take part in this
process, and the whole of the mother-cell is parcelled out into daughter-cells, or one
portion of protoplasm only including the nucleus is separated from the other parts
and applied to the formation of daughter-cells, while the remainder is not used for
this purpose, but is subsequently turned to account in some other way. The former
process bears the traditional name of cell-division; the latter, from an original
misapprehension, is termed free cell-formation. The expressions fo/al and partial
division would better describe the phenomena as they are understood at the present
day.

Bp Both modes of cell-formation occur in the formation of the reproductive cells
which we are considering ; in the majority of cases the division is total. Asci afford
beautiful examples of the so-called free cell-formation. In some cases, as in the
formation of the spores of Mucor and the Saprolegnieae, it may be a question to
which of the two types they belong. Excepting such doubtful cases, all cases of total
division are cases of bipartition with formation of firm partition-walls. Of the details
of the process of division we know no more than we know in the case of the division
of vegetative hyphae ; we can only say that a partition-wall makes its appearance.

The following are the chief modes of formation of spore-mother-cells and spores,
distinguished from one another partly by the differences which have just been
indicated and partly by peculiarities of form which present themselves in the process
of division.

Section XVI. 1. Intercalary formation (Intercalare Bildung). A delimitation
(Abgrenzung) takes place of portions in the growing hyphae, and the cells constituting
them become distinguished by their form and structure, acquire the characters of
spores or spore mother-cells, and at length become free by the gradual decomposition
or swelling of the parts that support or connect them. Their position is not uniform
in the cases that are known to us.

Normal formations of this kind are the resting spores of Protomyces,
Cladochytrium, the spores of Entyloma, and the not infrequent cases of the formation
of gemmae already briefly mentioned. ,

2. Acrogenous abjunction? (Acrogene Abgliederung). Delimitation of the
extremities of hyphal branches with limited growth takes place by means of trans-
verse septa for the purpose of forming reproductive cells, which are therefore placed,
at least during their formation, at the apex of a stalk or sporiferous structure named
since Léveillé dasidium or sterigma (ascus suffultorius of Corda). In more highly differ-
entiated species the basidium is the peculiarly formed terminal cell of a hyphal branch,
and the spores are frequently the extremities of slender stalk-like ramifications of this
cell. In this case the actual stalks of the spores are termed sterigmata in a narrower

1 [See the sections in which the Mucorineae and Tremellineae are described.

2 The distinction between ‘ Abgliederung’ and ‘ Abschniirung’ (see section XVII) finds no ex-
pression fin English Lotanical terminology, whilst the idea implied in both has been rendered by the
term ‘abstriction.’ If this term could be restricted to what is designated by ‘ Abschniirung,’ it might
be retained as satisfactory; but unfortunately it has come to be used so generally in the sense of
‘ Abgliederung,’ that to avoid confusion it is altogether discarded in the text and the term “abjunction ’
(with the verb to ‘abjoint’) is introduced as rendering ‘ Abgliederung,’ and ‘abscision’ (with the
verb to ‘ abscise’) is used to express ‘ Abschniirung.”]

62 DIVISION I.—-GENERAL MORPHOLOGY.

sense of the word and the cell from which they spring is the basidium. In species of
more simple character both expressions are used according to convenience. Among
the manifold variations in individual cases which must be left for special description
there are at the same time a number of generally recurring phenomena according to
the mode of abjunction, the numerical relations, and the ultimate shedding of the
abjointed portions.

As regards the form which may be exhibited by the phenomenon, the cross
septum may appear beneath the apex of the sporiferous cell, the apex itself being
usually expanded: the portion thus delimited is the spore; the breadth of its base is
about equal to that of the sporiferous cell. The simplest examples are most uredospores
(Fig. 26) and the teleutospores of Uromyces. A second case is that in which branches
grow at certain points from the sporiferous cell and these are either abjointed at the
point of insertion, which usually becomes much constricted after the manner of the

FIG. 26. Puccinta graminis, FIG. 27. a—d Auricularia Auricula Fudae. Development of basidia and spores ;
Small piece of a hy jum; 2 ive stages of the development according to the letters. @ cylindrical terminal cell
uresdospores with four germ-pores of a hypha from which several basidia are formed by transverse division 5; each of the
in their equator, 7 a pair of teleu- basidia puts out a long narrowly conical sterigma (c, @) from its upper extremity, and the
tospores, the upper with a germ. swollen apex of the sterigma is abjointed as a spore s; x a sterigina from which the spore
pore in its apex. Magn. 390 times, has fallen. /the development of the basidia of Extdia spiculosa, Sommerf.; four basidia are

formed from the cell 5 by divisions crossing one another in the cell; the other parts of the
figure show younger and later states; sa spore. The dotted lines indicate the surface of the
hymenium. /after Tulasne highly magnified. a—d magn. 390 times.

sprouts in the species of Sprouting Fungi (p. 4), or they elongate into slender stalks,
sterigmata in the narrower sense mentioned above, and their swollen extremity forms
by abjunction a spore. Examples, to be again noticed, are to be found in the
Basidiomycetes, in Eurotium, Penicillium, Haplotrichum, Peziza Fuckeliana, &c.
Intermediate cases occur, as might be expected, between the extremes and
require no further description.

A sporiferous cell or basidium may produce only one reproductive cell by acro-
genous abjunction, or several, even many, may be formed. The first is the case in
most species of the former of the two categories just mentioned, for instance in the
uredospores of Puccinia, Uromyces, and others. The basidia of Entomophthora are
examples of the second case, and those of most species of Tremella, Exidia, and
Auricularia Auricula Judae with long sterigma-shoots, the swollen apex of which
becomes a spore by abjunction (Fig. 27).

CHAPTER III-—SPORES OF FUNGI. 63

The acrogenous abjunction of the greater number of propagative cells is either
simultaneous or suecessive. It is simultaneous when a number of shoots make their
appearance at the same time at the apex of the basidium, grow with the same rapidity,
and experience abjunction at the same time, either at their point of insertion or beneath
their apex which is borne by the stalk (sterigma). The protoplasm of the basidium
is used up in the process and is not again renewed. Simultaneous abjunction is
especially characteristic of the
basidia in the hymenia of most
Basidiomycetes (Hymenomyce-
tes, Gastromycetes (Figs. 28, 29),
Calocera, Dacryomyces). The
basidia in these are generally
club-shaped terminal cells of hy-
phal branches, and spores are
abjointed at their broad apices,
usually as the extremities of long
sterigmata, more rarely as sessile FIG. 28 Octaviania carnea, Corda. Thin sections through the

hymenium. 4, 5 basidia, one of them with two spores in the act of forma-

sprouts of elongated or rounded tion, paraphyses. Magn. 390 times.

shape, as in Geaster hygrome-

tricus, Scleroderma, Polysaccum, and Phallus. The number of spores is in the
large majority of cases 4 to each basidium, in some cases 2, as in Calocera,
Dacryomyces, some species of Hymenogaster and Octaviania, in a few cases 6-9,
as in the Phalloideae, Geaster, and Rhizopogon. Slight variations from these regular
numbers are not unfrequently found, especially in the species which do not form
four spores on each basidium; in the Hymenogastreae, as in Hymenogaster
Klotzschii, basidia are found which form only one spore.

Ad
FIG. 29. Basidia of Gastromy on their basidi @ basidia of Geaster hygrometricus with eight sessile
spores. @ four-spored basidia of Lycoperdon pyriforme. c four- to eight-spored basidia of Phallus caninus. Magn.

390 times.

Outside the group of Hymenomycetes basidia which produce many spores
simultaneously occur in a great variety of forms on many gonidiophores, as in Peziza
Fuckeliana, Botryosporium, Haplotrichum, and Gonatobotrys. The number of spores
abjointed is normally higher in such cases than in the Basidiomycetes ; they are usually
placed close together on short stalks, so that we may speak of spore-heads formed
simultaneously. ‘The typically unicellular branches of Peronospora which abjoint
gonidia may be included with the above, especially if we take into consideration the
form distinguished by Cornu under the name of Basidiophora.

The simultaneously plurisporous basidia of the Basidiomycetes are usually more
or less broadly club-shaped before the formation of spores, as has been already

64 DIVISION I.—GENERAL MORPHOLOGY.

said; in Calocera and Dacryomyces they are cylindrical thin-walled cells rich in
finely-granular protoplasm, which either entirely fills their inner space or is interrupted
by vacuoles. It may be assumed that there is a nucleus always present, though in
the smaller forms it has been looked for in vain up to the present time. Where
it has been observed, as in Dacryomyces, Calocera, Corticium calceum, and especially
in ‘the basidia of Corticium amorphum (Fig. 30) which become $mm. in length,
it is a spherical weakly refringent body (perhaps the nucleolus), lying in about
the centre of the cell. It is not to be seen in the early states of the basidium,
and it disappears when the formation of sterigmata commences. More exact
investigation into its behaviour in spore-formation has yet to be made. When the
basidium has reached its full size, the sterigmata make their appearance on its rounded
apex as narrow subulate sprouts, and when they have arrived at a certain length their
extremity, which up to this time is finely pointed, swells into a vesicle which gradually
acquires the form, size, and structure of the mature spore. As the spore advances
to maturity the protoplasm of the basidium passes into the swollen extremities,

a

FIG. 30. Cortictum amorphum, Fr. Development of the spores, the successive stages being in the order of the letters.
@ a nearly mature basid with cell-nucl / basidium with two ripe spores, two others having already dropped off.
Magn. 390 times.

and at length, when the spores are nearly matured, the delimitation of them by cross
septa takes place; the basidium has by this time given up the largest part of its
protoplasm, but retains a thin parietal layer and is still turgescent. A clear central
spherical portion may be distinguished in the young fresh spores of many species;
it remains to be determined whether this is a nucleus and has proceeded from
the nucleus of the basidium.

The point of abjunction of the spore is either exactly at the apex of the sterigma
or a little below the apex at a bend turned outwards (Fig. 30), so that the spore
when detached takes with it the apical portion of the sterigma as a short stalk, or in
a few cases, as in Bovista and some species of Lycoperdon, abjunction occurs at the
point of insertion of the sterigma, which is consequently attached as a long stalk to
the spore when the latter becomes free. In the cases mentioned above, where there
are no sterigmata, abjunction as far as is known takes place in the way described.

Arthrobotrys (Fig. 21) will serve as an example of another form belonging to this
category.

CHAPTER III.—SPORES OF FUNGI. 65

In basidia exhibiting successive abjunction of many propagative cells the process
of abjunction is repeated several times on the same basidium. ‘There are three very
distinct sub-forms of successive abjunction, each of which has some special pecu-
liarities connected with it. These sub-forms may be distinguished as the sympodial
and the serial or concatenate (Reihen-weise, Kettenweise), the latter being again divided
into the szmple and the branched.

In the swecessive sympodial form (Figs. 31, 32) a single acrogenous spore is first
of all abjointed from the extremity of the basidium or sterigma, which is always finely
pointed. Then a new protuberance sprouts forth close to the point of insertion of
this first spore, pushes it on one side and occupies the extremity of the sporophore,
and is there abjointed as a new spore. A like proceeding may be repeated many
times; the last spore formed is always at the apex, and its older sisters are ranged on
the same plane or one after another below the apex. In very extreme cases the

FIG. 31. Dactylium macrosporum, Fr. Extremities of spori- “ FIG. 32. Botrytis Bassii, Bals. a end of a
ferous hyphae. a ina dry state with a head of spores above. 5 young sporiferous hypha; short lateral branchlets
in water with the primordia of the youngest spores s at the have successively abjointed each 1-4 round spores.
ext ities of the b hes, the small beneath 6 end of an old branch which is producing spores
being the points of attachment of the older spores which have by abjunction and is thickly covered with spores,
become detached in the water. Magn. 300 times. the youngest of which are terminal. ¢ two sporo-

genous branches, from which all the spores “have
fallen with the exception of the youngest and
uppermost. @ magn. 390, 5 about 700 times. See
Bot. Ztg. 1867.

spores are very soon entirely detached and either fall off or remain adhering only to the
one last formed, as happens in the formation of the gonidia of Epichloe typhina, in
Claviceps and in the forms known by the name of Acrostalagmus of Corda. In other
cases, aS Botrytis Bassii and the small gonidia of species of Hypomyces and
Hypocrea', each spore arises at least far enough above its predecessor for the points
of insertion to occupy some space, and the spores therefore remain united into
sympodial successive heads. If the spores are detached, their insertions form slight
projections or even short stalks at the extremity of the sporophore (Fig. 32). If the
sporophore were to elongate between each pair of spores a sympodial arrangment
would be produced, like that of Phytophthora in Fig. zo.

1 Verticillium agaricinum and its allies, Trichoderma viride, &c. See Tulasne, Carpol. III.

(4] F

66 DIVISION I.—-GENERAL MORPHOLOGY.

In the simple successive serial or concalenate forms the abjunction is repeated
beneath the insertion of each propagative cell in the same direction and in the same
form as in the case of the first cell. If the line of abjunction in that case was broad
and transverse, the extremity of the sporophore beneath the youngest spore elongates
to a definite extent and abjunction again takes place by formation of a new trans-
verse wall; if the first sprout which becomes a spore has a constricted insertion, then
after each abjunction a similar sprout with constricted base is developed beneath it
from the persistent end of the sporophore and in turn undergoes abjunction. In
this way a chain of similar segments is produced, in which the cells are younger in
proportion as they are nearer to the extremity of the sporophore from which they are
formed. The number of cells in a chain
may be considerable, 20-30 or more.
Examples are to be found in the gonidia
of most of the Erysipheae, Cystopus,
Penicillium, Cordyceps, and the Aecidieae,
in the uredospores of Coleosporium,
Chrysomyxa, and many others (Fig. 33).

Branched serial or concatenate forms
arise when one or more outgrowths stand-
ing side by side on the apex of a filiform
sporophore are abjointed, and then by
repeated abjunctions produce a structure
not unlike one of the Sprouting Fungi
(Fig. 3). The first sprout-cell puts out
one new protuberance from the apex
which is remote from the sporophore, and
this new cell and each succeeding one
can do the same; a row of cells is thus
formed in which the members are succes-
sively younger as the apex is approached.

Each of them can then form one or more
Cee ee eee ae herzus lateral sprouts below its apex which adjoins

is further explained in the text on . & Eurotium A. - .
Pitta plabeurs end sach sn m «7 the cell next above it, and these new cells

sergmta on which the formation of spores je begining’ and their progeny are similar to the first
Spores; 1 youngest spore of a chain. a magn. 39, the rest 00 (Fig, 34). According as the lateral sprouts

on cells of successive orders are placed
singly or in a whorl of two or more members, chains are produced in which the
branches vary in number and form. The cells of all orders are so many repro-
ductive cells which are similar to one another in all important points and become
ultimately detached from one another. Examples of this kind occur in the forms
named by Fresenius! and Riess? Periconia, in which sprout-chains are collected
together into a compact head at the extremity of a filiform sporophore, and in the small

gonidial forms of Pleospora and species of Fumago and its allies in the Sphaeriaceae ®,

1 Beiträge. 2 Bot. Ztg. 1853.
® Tulasne, Carpol. IT.

CHAPTER III.—SPORES OF FUNGI. 67
of which those named Cladosporium herbarum, Dematium herbarum’ and Alternaria
are the best known; to these may be added the delicate heads of Myriocephalum
botryosporum? and many others.

Connected with these three kinds of acrogenous
abjunction of spores is one which is less distinctly
marked and which may be termed the mode of cross-
septation (Querzergliederung). In this the terminal por-
tion of a hypha or hyphal branch grows first of all to v
a certain length, and then ceases to elongate but is divided
by cross septa into a number of spore-cells.

This mode of formation is seen most distinctly in
the sporogenous branches of strong specimens of Oidium
lactis? which rise into the air above the substratum.
These branches have a cylindrical form and are many
times longer than broad. When they have ceased to
elongate they quickly divide by formation of cross septa
into numerous cylindrical spores which are from one to
two times longer than broad. In small specimens this
cross-septation may extend over the whole plant, occur-
ting even in the branches of the mycelium in the
substratum. The formation of cross septa appears to
commence in stronger individuals at the free apical
extremity and to advance basipetally; but this point
is quite as uncertain as the question, whether the sporo-
genous branch consists at first of a number of longer
cells which are afterwards divided into the short members
by repeated intercalary bipartition, or whether the latter
are the first divisions formed either simultaneously or
successively and in basipetal order in the branch which 54, 34 Species of Altrnariz. a
was up to the time of their formation unicellular; on and > sxtemitics of 2 | spor!

hypha growing obliquely into the air
these points further examination of the branches of fom @specimen grownon a mi i
this Oidium is to be desired. Of similar character are

the gonidial mother-cells of Syncephalis and Piptoce-
phalis*, which spring simultaneously from the apex of
the capitate extremities (basidia) of the sporophores and
form a small clustered head. They have the form of
elongated cylinders with rounded apices, and are divided
after they have ceased to grow in length into several

slide, zonthe4th Aug. at midday, dsome
23 hours later; the two rows of spores
which are still simple in a are branched
ind. c a young sporophore on a my-
celial filament submerged in water. The
membranes of the pointed ovoid spores
are yellowish brown where they show
partition-walls in their interior and are
colourless only at the upper pointed
extremities, This is the case also with
the youngest and still small spores, the
sporophores and the mycelium. aand 5
Magn. about 145, c 225 times.

short cylindrical spores by transverse septa formed either simultaneously or succes-
sively and in basipetal order, but always very rapidly.

1 Low in Pringsheim’s Jahrb. VI, p. 494. Penicillium cladosporioides, P. viride, P. chlorinum, all
of Fresenius (Beitr.), and P. olivaceum, Corda, are evidently the same form. Even if Tulasne’s view
that the plant belongs to Pleospora herbarum is not confirmed, its connection with one of the allied
Sphaeriaceae is more than probable. ? Fresenius, Beitr. t. V.

3 Fresenius, Beitr.—Brefeld, Ueber Gährung in Thiel’s Landw. Jahrb. V, 1876, t. II.

* De Bary und Woronin, Beitr. II. Brefeld, Schimmelpilze, I. Van Tieghem et Le Monnier in
Ann. d. Sc. nat. Ser. 5, XVII, p. 370. See also below, sect. XLIII, Fig. 74.

F2

68 DIVISION I.—-GENERAL MORPHOLOGY,

The spore-formation in Ustilago and Geminella, which will be further considered
in section LV, appears from Winter’s observations on Geminella and Ustilago
Ischaemi! to be nearly allied to the cases just described. More certainly is this the
case with many acrogenously formed so-called sep/are spores, as those of Puccinia
(Fig. 26 4) and Phragmidium, and many forms of Hyphomycetes, the systematic
position of which has not yet been exactly determined, Trichothecium, Arthrobotrys
Fusiporium, &c.; also forms which we now knowas gonidiophores of the Pyrenomycetes,
such as Fries’ groups of the Dematieae and Sporidesmieae, Helminthosporium,
for example, Cladosporium, Alternaria, Sporidesmium, Phragmotrichum, Polydesmus,
Melanconium, Stilbospora, Coryneum, Exosporium, and very many other forms. See
Figs. 21 and 34, and section XXIX.

Section XVII. The inception (Anlegung) of acrogenously produced spores
takes place in every instance according to one or other of the processes which have now
been described. In some also ripeness, that is the capacity for further normal develop-
ment, and the size, form, and structure which indicate this capacity, is reached, as has
been repeatedly stated above, when the delimitation is completed. This is the case,
for example, in Cortictum amorphum (Fig. 30) and in many, perhaps in all the
Basidiomycetes, and to a certain degree in Cystopus Portulacae (Fig. 33); in the
case of many other small spores attached by a very narrow stalk it is not possible to
speak with certainty on this point, because the minuteness of the point of insertion
renders it impossible to determine the exact moment when delimitation by the cross
septum is effected. On the other hand, many cases are known in which after acro-
genous delimitation the cross septum undergoes a considerable amount of growth before
it is mature, and it obtains the necessary food for this purpose from the sporophore ;
this is the case, for example, in all the species of the Uredineae mentioned in the pre-
ceding sections, and in Eurotium and Penicillium, &c. In a rapidly growing successive
chain in these species the majority of the younger members are still immature, and
the nutrient material, so far as it comes from the sporophore, must pass by the younger
cells to reach the older more distal ones.

Many acrogenous spores are Zersisien! on the sporophore after they are mature,
and are carried away from the place where they were formed only by accidental
external mechanical agencies, as the teleutospores of Uromyces, Puccinia, and
Phragmidium, the large gonidia of Hypomyces and many other septate forms above
mentioned.

But the larger part of these spores are defached from the sporophore as soon as
they are mature by the aid of internal causes, which during the process of ripening
bring about certain changes in the original condition and thus render the ultimate
separation possible. The three chief modes known to us in which this purpose
is effected are the disappearance of the sporiferous structure (Schwinden der Trager),
abscısion? (Abschniirung), and adyection ® (Abschleuderung).

The disappearance of the sporiferous structure is most common among the
Gastromycetes, in which, when the spores are ripe, not only the basidia, but usually

1 Flora, 1876, Nr. 10, 11. ? See note on page 61.
3 See note on page 84.

CHAPTER III.—SPORES OF FUNGI. 69

also the rest of the hymenial tissue, becomes entirely dissolved by processes of decom-
position not accurately known, and the spores are thus set at liberty. They lie at first
in the place where they were formed; their subsequent fortunes are described in
Division II. The history of the basidia, which make their appearance as branches
of the simple sporophores and form gonidia in Peziza Fuckeliana (‘Botrytis cinerea’),
is essentially the same. They disappear entirely after the gonidia are ripe, and the
latter cling in loose heaps to the place of their formation. :

The process of abscision is the most common of the three and appears with the
greatest variety of forms. Generally a transverse zone between the adjacent cells
disappears or grows soft, and their separation is thus effected or made easy. The
transverse zone which disappears is either
a middle lamella of the cross septum
between the two cells or it is a small
stalk-cell, which is cut off from the young
spore by a cross septum and then dis-
appears, as in the uredo-chains of Coleo-
sporium and Chrysomyxa and all the
Aecidieae. The changes observed in the
zone of separation are in one series of
cases simply that it becomes gradually
smaller and especially narrower and at
length entirely disappears; in other cases
it swells up into a jelly and becomes
disorganised. The product of the swelling
may in the latter case be persistent, and
is then usually increased to a considerable
extent by the gelatinisation of the lateral
walls of the spores, which are therefore
ultimately glued together by a gelatinous
mucilaginous gummy substance ; in other
cases the products of disorganisation at
length entirely disappear, and complete —_Fic.as. @ Cystopus Portulacae; m mycelial branch bearing
isolation of the spore is effected. It is i explained in tne um 6 Euronen paren
natural to suppose that this process de- on which ee of oo ee ai
scribed as disappearance consists in a syoungestsporeofactiin a mark meet
transformation into soluble compounds
and a simultaneous osmotic absorption of these into the adjacent cells, especially
in the many cases in which the spore about to be removed by abscision continues
to grow while the disappearance is proceeding, and would seem therefore to be
receiving more food. In some cases one might also suppose a process of com-
bustion. Precise statements on these points are not possible in the present state
of our knowledge.

These phenomena are well exemplified in.the simple successive gonidial rows in the
genus Cystopus, especially in C. cubicus and C. Portulacae (Fig. 35 a), which latter
plant is more particularly referred to in this place. Delimitation of the rounded apical
portion of the basidium (2) is effected by a broad cross septum to form a gonidium (v).

70 DIVISION I.—-GENERAL MORPHOLOGY.

The septum appears first as an annular ridge on the inner side of the lateral wall
of the basidium, and grows slowly into a plate of considerable thickness which is
convex on the side towards the basidium and correspondingly concave on the other,
and shows the bluish lustre of gelatinous membranes under the microscope. When it is
fully formed the apex of the basidium elongates to form a new gonidium. The
new portion thus formed is close under the transverse septum. In correspondence
with the subsequently rounded form of its apex it is from the first somewhat
narrower than the septum, and by its elongation it separates the septum at its
margin from the lateral wall of the basidium and carries it upwards with the goni-
dium to which it belongs. Each gonidium accordingly has its slightly convex
surface resting at first on its younger sister with the margin free, but attached to
its apex by the broad middle portion. The gelatinous cross septum, to which
the whole of the surface of attachment belongs, is continuous above with the lateral
wall of the gonidium; and while this becomes slightly thickened as it developes,
a membrane, which is not at first clearly defined, is formed on the inner surface
of the septum and is also continued into the lateral wall which it resembles in
appearance; this is the persistent basal wall of the goni-

dium. At the same time the original gelatinous transverse

septum begins to disappear from its margin inwards as if it

melted away. There is now in all beyond the third and

fourth youngest gonidia of a row only a quite narrow in-

termediate piece in the middle connecting each with its

younger sister. This piece is of about the same height as

the original septum, but the bluish glistening substance in

it dwindles from below upwards into a small plate which

becomes continually thinner and remains attached to the

wall of the gonidium to which it belongs. As this process

goes on the intermediate piece becomes pale and very

slightly refringent, and after persisting for some time in

this state at length disappears. There is no reason for

b 2 regarding this delicate intermediate piece as a part of an
outside membrane which covers the whole gonidial chain

FIG. 36 Penieitium glaucum. ike a sheath, as I formerly did. The single gonidia show

@ young gonidiophore with the com- 7
mencement of successive serial ab- no important changes after they are detached from the

Sen. en gonidiophore beyond the thickening of their membrane
are en wie alone already mentioned, which cannot be further pursued here.
and glycerine. Magn. 600 times. Most of the propagative cells formed by acrogenous

abjunction which have now been mentioned are detached
by abscision in the manner described above, and, like the cells of Sprouting Fungi,
they must become detached by disappearance of an original intermediate lamella
just as is observed in Cystopus. Careful examination shows indications of this in
almost all cases, but the, details of the proceeding are often difficult to follow on
account of the too small size of the parts, yet it can be seen very distinctly, in spite
of their small size, in the successive gonidia-rows in Eurotium and Penicillium, not-
withstanding their minuteness (Figs. 35 4 and 36). Some further details may be seen
in Zalewski’s treatise, mentioned at the end of this chapter.

In a certain number of forms the separation is effected by the formation of a
gelatinous or gum-like deliquescent substance both on the surface of separation
and on the rest of the circumference of the spore. It must be supposed that this
substance also is the product of an outer lamella of the spore-membrane which
was not originally gelatinous ; but the minuteness of the objects prevents this from
being certainly ascertained. With the ordinary amount of moisture necessary for
the growth of Fungi the deliquescent substance absorbs so much water that the
spore when abjointed is easily detached; a drop of water washes it away at once,

CHAPTER III. —SPORES OF FUNGI. 71

if kept dry it will continue to adhere to the gonidiophore. Spores abjointed
close together in large numbers cohere through the coalescence of their gelatinous
envelopes and form masses which break up again in water. In the case of spores
successively abjointed on the free apex of one or several closely adjacent sterigmata,
if the development takes place without interruption in a damp atmosphere, the
gelatinous substance deliquesces and forms a spherical drop, in which the spores
lie embedded as in a vesicle. And all this occurs alike in those cases where the
successive abscision affects spores arranged in rows (gonidia of Nectria Solani’)
and in those where they are in heads (Acrostalagmus cinnabarinus, gonidia of
Claviceps and Epichloe). Where abscision of large numbers of spores takes place
inside narrow receptacles provided with narrow orifices, their release from the
receptacle is effected by the formation of a gelatinous or gummy substance which
swells in water and emerges with the spores from the
receptacle. Examples are to be seen in numerous gonidia-
receptacles in the Pyrenomycetes. See Division II.

A description of the development of the spore-chains
in the aecidium of Chrysomyxa Rhododendri’ will show
the mode in which the spores are shed in the Uredineae
by the solution and disappearance of a stalk-cell or in-
termediate cell beneath each spore. The spores in each
chain are formed by successive abjunction at the upper
extremity of a short club-shaped basidium, from which
at first an almost cylindrica] spore-mother-cell is abjointed
by a plane transverse septum. This cell, which is about
one and a half times longer than broad, subsequently
changes its shape; one side bulges considerably, the
other only slightly, and the whole cell thus becomes
irregularly barrel-shaped. It is then divided into two
unequal daughter-cells by a plane partition-wall which
runs from the angle formed by the basal cross septum
and the more prominent side obliquely towards the
flatter side, cutting off the lower third part of it; the
lower of the two daughter-cells is a small wedge-shaped
stalk-cell or intermediate cell, the upper is larger and
developes into a spore. The spore is at first of a some-
what complex and irregular form, as is sufficiently apparent
from what has been said above and from the Fig. 37. It FIG. 37. Chrysomyxa Rhododen-
increases considerably in size, assuming in so doing a um an amanma chan of spores
nearly spherical or ellipsoid figure, and becomes invested thetext. Magn. 600 times.
with a new membrane of considerable thickness, into the
structure of which we must not at present enter. The stalk-cell grows at the same
time in height and breadth, remaining much lower on the side where its wedge-form
thinned out originally than on the opposite and now convex side, and has an
elliptic transverse section. Ultimately the stalk-cell disappears, its membrane and
the outer primary lamellae of the membrane of the mother-cell and of the transverse
septum swell up, become gelatinous, and finally vanish entirely with the cell-contents,
and the spores are now isolated. The division into stalk-cell and spore is usually
found in the third youngest spore-mother-cell on a basidium, more rarely in the fourth
youngest. The gelatinous dissolution of the stalk-cell is usually far advanced in the

1 De Bary, Kartoffelkrankheit, p. 41. Reinke und Berthold, Die Zersetzung d. Kartoffel durch
Pilze, p. 39.
2 Bot. Ztg. 1879, p. 803.

72 DIVISION I.-—GENERAL MORPHOLOGY.

one belonging to the sixth youngest spore in the chain. Phenomena essentially the
same occur in other species of the Uredineae, but with considerable variations in form
in the different species.

Where filiform sporophores rise free into the air, a further mechanical arrange-
ment is found which greatly assists the shedding and scattering of the abscised
spores. It may be readily observed in the Hyphomycetes, in Peronospora, for example,
Phytophthora infestans, and in the gonidiophores of Peziza Fuckeliana, &c. The
hyphae of these Fungi are cylindrical in the moist and turgescent state, but collapse
when dry and especially when the spores are ripe into a flat ribbon-like form’,
and the drier they are the more strongly do they become twisted round their own
longitudinal axis. They are so highly hygroscopic that the slightest change in the
humidity of the surrounding air, such for instance as may be caused by the breath
of the observer, at once produces changes in their turgescence and torsion; the
latter give a twirling motion to the extremity of the
gonidiophore and the ripe spores are thereby thrown
off in every direction.

Abjection of acrogenous propagative cells is effected
by a mechanism which we shall have to speak of again in
section XXI. The cell which is to be abjected, whether
spore or spore-mother-cell (for brevity we shall call it
spore), is abjointed singly by a cross septum at the apex
of a tubular and often comparatively large sporiferous
cell, a basidium or a sterigma, which retains its parietal
protoplasm still intact after the abjunction of the spore
and is still turgescent in consequence of a continued
pie Be Pieteen cota. Mane supply of water in increasing quantity. Its membrane

ogi Pf uectea ed is highly extensible and elastic, and continues to stretch
ee ei “AS the tension increases with the increased amount of
ir Ile tie Meer of the: Water absorbed. But its cohesion is less over an annular
area immediately beneath the cross septum than in
any other part of the circumference, and if the tension reaches a certain point,
it overcomes the resistance of the less coherent annular zone, the suture of
dehiscence; the wall opens by a circular fissure, the pressure of turgescence is
instantly relieved and the elastic wall contracts, especially in the direction of the
transverse diameter, and this causes a large part of the fluid contents to be squirted
out at the same moment with force through the fissure, and as it strikes full on the
transverse septum, the spore that rests upon the septum is abjected with it. The
basidium thus emptied collapses and perishes. 2

The process of abjection may be observed most completely in the acrogenously
abjointed spore-mother-cells of Pilobolus crystallinus and its nearest allies, of which
we shall speak again in later sections (Fig. 38). It occurs also, as Brefeld® has

1 Bot. Ztg. 1. c. p. 786. De Bary, Brandpilze, p. 59. Reess, Rostpilzformen d. Coniferen, Halle,
1869. R. Hartig, Wichtige Krankh. d. Waldbäume, t. IV, V.

2 Fresenius, Beitr. t. II.

® Bot. Ztg. 1870, p. 161. Abhandl. d. Naturf. Ges. zu Halle, Bd. XII, 1. 1871.

CHAPTER IIl--SPORES OF FUNGI. 73

shown, in the basidia of Empusa and species of Entomophthora. The ripe spores
are thrown to a distance of 2-3 cm. and adhere by the remains of the ejected proto-
plasm to the bodies against which they strike. The ripe spores of Coprinus, especially
C. stercorarius, are abjected from the basidia by the same mechanism, as Brefeld
informs us’. They are attached, as Fig. 30 shows in the case of other Hymenomy-
cetes, to the extremities of very slender sterigmata which spring four together from
the apex of a basidium. The four spores of each basidium are abjected at the same
moment, and a small drop of fluid which issues from the sterigma shows that it is
open at the apex, while a small quantity is also seen to be attached to each spore as
it drops. The similarity in the basidia and in the mode of formation of the spores
in all the Hymenomycetes and other facts also make it probable that the process of
abjection is widely spread, perhaps occurs universally, in this group of Fungi; but
more extended investigations are still needed to clear up this point.

The following are some of the other facts just’referred to. It has long been known
“that the hymenium of a Hymenomycete when turned upwards becomes gradually
sprinkled over with free spores, and if it is turned downwards, spores fall from it in
large quantities. Some of them fall in an exactly vertical direction, as appears from
the fact that the spores which fall on a piece of paper placed under the free hymenium
of an Agaric are arranged in radial lines answering exactly to the radial arrangement
of the lamellae on the pileus.

These phenomena are in themselves quite compatible with simple abscision as
described in the preceding pages, but they do not exclude the supposition that the
spores were abjected with some small exertion of force, as Brefeld has also
pointed out?. On the other hand a dispersion of the spores is observed in these
Fungi in other directions than that of the vertical. The statement of Bulliard?
has recently been confirmed by Hoffmann and de Seynes, that many spores fall from
the hymenium of an Agaric when turned downwards far beyond the line which
corresponds to the margin of the pileus. Hoffmann saw white clouds of spores
rise like smoke from Polyporus destructor when there was a slight movement
in the air, ‘but when the air in the closed chamber was perfectly still no spores
reached a glass plate hung at a distance of only three quarters of an inch above
the plant, while those which fell on a glass plate two inches and a half beneath
the Fungus covered nearly uniformly up to the margin a space of more than six
times the circumference of the Fungus.’ Other Hymenomycetes gave similar results.
These observations point to abjection of the spores, but do not absolutely prove it,
because the facts described might be due to movements of torsion in the sterigmata,
such as were noticed above on page 72.

Lastly, it may be observed that the abjection of the spores in Leitgeb’s Completoria *
may also have been caused by the mechanism which has already been described ;
Leitgeb’s own explanation I have not been able to understand.

Section XVIII. 3. Endogenous spore-formation (Endogene Sporenbildung),
Many spores are produced inside mother-cells, the wall of which remains intact till the
spores are ripe and forms a spore-receptacle or sporangium.

The sporangia are mostly acrogenous cells which are either persistent on their
sporangiophore, or are removed from it by abscision, as in Cystopus and other

! Schimmelpilze, III, p. 65.

2 Ib. p. 132.

* Champignons de France, I, p. 51.

* Sitzungsber. d. Wiener Acad. Bd. 84, July, 1881.

74 DIVISION I.—-GENERAL MORPHOLOGY,

Peronosporeae; more rarely they are intercalary. Their spores are produced by
division without formation of parting walls and conform to two chief types: 1. A
parietal layer of protoplasm at least is not included in the division and is left behind
in the sporangium, as is the case in asci. 2. No parietal layer remains behind, as in
the sporangia of the Phycomycetes, which show much variation in details.

a. In the sporangia ofthe Phycomycetes the whole of the protoplasm, whether
parietal and enclosing a vacuole or filling the lumen of the cell, is divided to form the
spores. The number of spores directly produced by the division is not fixed in any
species except perhaps in Tetrachytrium‘, and is often very large, as in Mucor, Pilobolus
and large Saprolegnieae. The division usually appears to be simultaneous ; but Biisgen
observed under very favourable circumstances in Leptomitus lacteus and Mucor that
the protoplasm was divided by very rapid bipartitions into successively smaller portions
up to the final formation of spores. When the division is complete the future limiting
surfaces of the spores are at first indicated by granular plates, but these are at once
replaced by homogeneous delicate and narrow partition-layers, which often however
become broader; these layers proceed probably from the blending of the grains and
usually continue of a soft gelatinous consistence, being directly transformed into plates of
cellulose only perhaps in species of Dictyuchus. In the Mucorini and in Dictyuchus
clavatus the spores which lie between such dividing layers become invested at once
with a firm cellulose membrane; in other species a distinct membrane does not appear
before the spore leaves the sporangium. The early stages of the division in
Aphanomyces show exceptional deviations from the ordinary type. No growth of
the spore when it has once been separated off takes place inside the sporangium in
any of the above cases.

The process of division may be observed in its greatest completeness in the
sporangia of the larger Saprolegnieae which live in the water; in Saprolegnia,
for example, Achlya and Leptomitus lacteus. The sporangium is a large club-shaped
cell delimited by a transverse wall from the unicellular tubular sporangiophore. It
is densely filled with a coarsely granular protoplasm, or may have a large axile
vacuole. Shortly before the division the protoplasm becomes everywhere uniformly
and finely granular and has small inconstant vacuoles at wide distances from each
other. It is then suddenly divided by granular plates, which look like rows of granules
when seen in profile, into numerous polyhedral or polygonal portions, the future spores,
which in Leptomitus, as was said above, are formed by rapid successive bipartitions.
The partition soon becomes more pronounced, the partition-streaks which were before
granular now become homogeneous, and no longer appear as fine clear lines but
grow broader as the spores are rounded off. With this the separation of the spores
is complete in the cases which we are considering: the substance of the partition-plate
which is derived apparently from the granules that were previously present continues
homogeneous, soft and capable of swelling. Colouring reagents, as Fr. Schmitz?
first discovered, show the presence of a number of nuclei in the sporangium as
soon as it is delimited, and a division of them afterwards. Each spore obtains a
nucleus, which has been directly observed to proceed in Leptomitus from the
division of the original nuclei. These processes which lead at once to the for-
mation of spores are however preceded by other separations in which the behaviour
of the nuclei has not been clearly ascertained. The coarsely granular protoplasm

1 Sorokin in Bot. Ztg. See also below, section LII.
2 Sitzsber. d. Niederrhein. Ges. Aug. 4, 1879.

CHAPTER III—-SPORES OF FUNGI. 75

of the sporangium is first divided into portions resembling the future spores in number,
position and size, and the division is effected by partition-plates which are at first
granular in character and afterwards become broad hyaline stripes. These subse-
quently disappear, and the whole of the protoplasm assumes the uniformly finely
granular appearance described above, and at once proceeds to the final division.
The same or very similar phenomena, and among them the preliminary transitory
separation, have been observed in Dictyuchus monosporus, but there in place of
the final partition-plates firm cellulose membranes are formed, from which the spores
subsequently escape. In Dictyuchus clavatus each spore is invested with a membrane of
cellulose, but is separated from its neighbours by a thin layer of a hyaline substance,
which is soft and gelatinous in water and must be formed from the partition-plates ;
it is still a question whether the membranes of the spores are obtained by differ-
entiation from the plates, or are a later product from the spores themselves.

In the Mucorini with endogenous spore-formation which do not grow in water
(Mucor, Pilobolus, &c.) the processes of division cannot be followed throughout under
the microscope; but whatever can be learnt about them from dead material agrees so
closely with the final stages of division in the Saprolegnieae, and especially with those of
Dictyuchus clavatus, that we are justified in assuming that the process of division is quite
similar. At first the spores are delimited as polyhedric bodies by very narrow partition-
plates: by and bye each is rounded off and invested with its own cellulose membrane,
as in D. clavatus, and separated from the others by a layer of gelatinous substance that
swells in water. In some species of Mucor (M. plasmaticus of Van Tieghem) this
intermediate substance is largely developed’, occupying in the intact sporangium
even more space than the spores themselves, and is finely granular. It may be
doubted whether the entire mass is formed in such cases from the partition-plates ;
it is possible that it is exuded from the spore-forming protoplasm before the division,
or comes also in part from the membrane of the sporangium (see section XX). Our
present investigations still leave the point unsettled. Preliminary separations have
not been observed with certainty in Mucor.

The description given above does not hold good of all the Saprolegnieae which
have been examined, and is true of Phytophthora only among the allied Perono-
sporeae. The only point in which all agree is in the ultimate appearance of the hyaline
partition-plates with capacity for swelling, and this remark applies also to the Chytri-
dieae ; some details with respect to the latter group which belong to this place will be
given in section XLVI.

Aphanomyces deviates from the Saprolegnieae to a greater extent than any other
of the allied forms. The spores are cylindrical, three times as long as broad with
rounded ends, and lie one behind the other in a single row in the slender cylindrical
filiform sporangia. At the commencement of their formation the granular parietal
protoplasm, which is from the first uniformly distributed but always remains parietal,
aggregates into dense transverse girdles, which are three or four times as long as broad
and are separated from one another by shorter hyaline transverse zones, in which
only a very thin almost entirely homogeneous parietal layer of protoplasm remains
attached to the membrane. When the granules originally distributed in coarse irregular
streaks have become uniformly distributed in the thick girdles, annular constriction
appears in the parietal layer in the middle of each hyaline transverse zone, and
advances in the centripetal direction till the zone separates into halves which
become absorbed in the adjacent thick zones. These at the same time have become
spores, and are separated from one another by hyaline interstices filled probably with
a substance which is less dense and more capable of swelling. The behaviour of the
nuclei in this proceeding has not been investigated. Further details will be found
in Biisgen’s treatise cited at the end of this chapter.

1 Brefeld, Schimmelpilze, I, 16.

76 DIVISION I.—GENERAL MORPHOLOGY.

Section XIX. 6. The asci (thecae) are in almost all cases the solitary
terminations of hyphal branches; several or many of these asci, in most cases
a very large number of them, arranged nearly parallel to one another and with hairs
(paraphyses, section XII) between them are grouped together to form hymenia, which
in the Discomycetes are open superficial layers on the sporophores, ‘but in the Pyreno-
mycetes are in the interior of receptacles (perithecia) which are either closed or
provided with a narrow orifice. See sections LIX-LXII, where some account is
given of the exceptions to the rule thus briefly stated.

The formation of the asci is not essentially different from that of other terminal
cells of hyphal branches. They are generally club-shaped, more rarely broadly
ellipsoid or are stalked spheres as in Tuber, Elaphomyces, Erysiphe, Eurotium, and
others; and when once orientated they grow on usually without interruption till they
attain their definitive shape and size and then in most cases begin immediately to
form spores. It is only in some species of Erysiphe that the formation of spores
is preceded by a longer period of rest ; it is indeed possible that young immature
asci may pass through the winter period of rest in the case of species which, like
Rhytisma and its allies, form their spores in spring, but this has never been directly
observed.

In the very large majority of cases eight primordia of spores are formed simultane-
ously in each ascus; the facts connected with this proceeding were carefully
investigated by myself in 18631 in certain species of Peziza, Helvella, and Morchella,
by Strasburger ? recently in Anaptychia ciliaris, and by Fr. Schmitz* in species of the
same genera and of Ascobolus, Chaetomium and Exoascus, with the following results.

In a number of Pezizas (P. confluens, P., Fig. 39, P. pitya, P.) the young ascus is
filled with finely granular protoplasm containing vacuoles; a nucleus may be seen in
the centre of the protoplasm, as soon as the tube has reached about a third of its
ultimate length, in the form of a clear spherical body, in the centre of which is another
smaller and strongly refringent body. It has yet to be learnt whether the whole
body should be called the nucleus and the inner and smaller body the nucleolus, or
whether the latter alone is the true cell-nucleus.

As the ascus elongates the protoplasm moves into its upper extremity, and the lower
portion, which may constitute three-fourths of the whole length, now contains only a
more. watery fluid and a thinner parietal layer of protoplasm. When the ascus has
reached its full length, the commencement of spore-formation is indicated by the
appearance of two smaller nuclei in the place of the original nucleus. In a later stage
four nuclei are seen and then eight; the nuclei are always of similar structure but
their size diminishes as their number increases. Their arrangement and Strasburger’s
observations on Anaptychia leave no doubt that they are produced by successive
bipartitions from the primary nucleus. The eight nuclei of the last order are about
equidistant from one another, and are each ultimately surrounded by a sphere of
protoplasm, which is distinguished from the rest of the protoplasm by its greater
transparency and has a very delicate line of delimitation. These portions of protoplasm

1 Die Fruchtentwickelung d. Ascomyceten, p. 34.
? Bot. Ztg. 1872, p. 272. Zellbildung u. Zelltheilung, Aufl. 3, p. 49.
3 See above on page 16.

CHAPTER III,---SPORES OF FUNGI, 77

are the commencements of spores; they are formed simultaneously and soon become
invested with firm membranes, and grow as they lie arranged in a longitudinal row
inside the ascus to about double their original size. The protoplasm which surrounds
them at first disappears rapidly in Peziza pitya as they increase in size, and like the
protoplasm contained in the spores is always coloured yellow by iodine in this species.
The protoplasm of the ascus before the spores are formed, and that within the spores
at all times, shows the same reaction with iodine in Peziza confluens. But after the
orientation of the spores the protoplasm of the ascus shows the characters of a
substance, for which I formerly proposed the name of epzplasm, and which is dis-
tinguished from ordinary protoplasm by being more highly refringent, by its peculiar

‚E

FIG. 39. Peziza (Pyronema) confinens, P. a a small portion of the hymenium; 2 a paraphysis, which is only attached
to the hyphal branches from which the three asci spring without originating in them. »—w full-grown asci, the successive
stages of the development in the order of the letters; in y—z the nuclei are multiplying, in v the spores are being formed,
in w they are mature. 7 young asci. Magn. 390 times.

homogeneous and glistening appearance, and especially by the reddish brown or. violet
brown colour which it assumes when treated with very dilute solution of iodine.
Errera! has recently shown that this reaction with iodine is due to the circumstance
that the epiplasm contains a relatively large quantity of glycogen permeating a
protoplasmic or albuminoid vehicle ; the term glycogen-mass, or shortly glycogen,
may therefore be substituted for that of epiplasm.

In some other species with large asci (Peziza convexula, P. Acetabulum ?, and
P. melaena, Helvella esculenta, H. elastica, and Morchella esculenta) the contents of the
ascus which are at first uniform are differentiated before the spores are formed into
protoplasm and glycogen-mass. The former aggregates in Peziza convexula into a

+ See above on page 6.
? The species named Peziza sulcata? in my work on the Asycomycetes belongs to P. Acetabulum.

„8 DIVISION I.--GENERAL MORPHOLOGY.

transverse zone lying in the middle of the ascus, or in most other species into a mass
which fills the upper third or fourth portion of the ascus; the remaining and especially
the lowermost portion contains only the glycogen-mass which is marked by many
vacuoles of varying size and arrangement. Sometimes, as in Morchella esculenta
and Peziza Acetabulum, the uppermost portion of the ascus above the protoplasm is
occupied by a layer of glycogen, the protoplasm filling a cavity with a sharply
defined outline in the glycogen-mass. The nucleus always lies in the protoplasm and
in or near its centre, at which point the spores are formed in these as in other species,
the mode of formation being essentially the same as that described above. The young
spore-primordia are in contact with one another in Peziza convexula and Morchella
esculenta. Only the first stage in the division and the ultimate eight nuclei, round
which the formation of spores takes place at once, have been directly observed in
most of the above species; the other stages have been seen only in Peziza convexula.
But the accounts which we possess and observations on the formation and division
of nuclei in other plants compel us to assume, that the process in the eight-spored
ascus are essentially the same in all cases and that the successive stages in the division
of the nucleus have simply been overlooked, owing partly to the rapidity with which
the operation is effected and partly to difficulties of observation of other kinds.

Numerous independent observations on a considerable number of Discomycetes with
eight spores formed simultaneously in one ascus have established the presence of
the primary nucleus before the formation of spores, the appearance of the young
spores in the manner just described, and the occurrence or non-occurrence of differen-
tiation of the glycogen-mass and protoplasm according to the species. There is therefore
no reason to doubt, that the course of development above described prevails very
generally in the group which contains the genera Peziza, Phacidium, Leotia, Ascobolus
and Geoglossum. It is often difficult to follow it throughout in large asci, like
those of Leotia lubrica, Geoglossum hirsutum, Helvella, &c., because the protoplasm
of the young tube and of the spores is rendered opaque by the number of drops of
oil. In very many other cases the minuteness of the asci and spores either prevents
a complete observation or renders it difficult ; but even in these cases a little attention
will enable us to see the primary nucleus, the simultaneous appearance of the eight
spores as portions of protoplasm with a fine boundary-line, and sometimes (Sclerotinia
sp.) a nucleus in each of them. Inthe small asci of e.g. Peziza tuberosa, P. Sclerotiorum,
P. calycina and Phacidium Pinastri, and also in some larger ones, as those of Lecidella
enteroleuca, Pertusaria lejoplaca, Lecanora pallida and Sphaerophoron coralloides,
the primary nucleus appears as a strongly refringent roundish body, which is either
homogeneous or more pellucid and as if hollowed out in the centre; the clear, trans-
parent, spherical space is not or not always (Peziza Fuckeliana) to be seen through the
periphery.

It is more difficult to observe the formation of the spores in the asci of the Pyreno-
mycetes containing eight spores formed simultaneously, than in the Discomycetes,
on account partly of the minuteness and delicacy of the organs, partly of the presence
of oil globules which are present usually in large numbers in the protoplasm. Yet
careful observation shows that the spores are formed in the way described above.
A nucleus has rarely been seen in them (Sordaria fimiseda, Fig. 52). An oil globule
was often taken for a nucleus by older writers. The primary nucleus on the contrary
may be distinctly seen in many species before the spores are formed; it has the
characteristics of the nucleus of Peziza calycina and P. tuberosa which have just been
described, and always lies in the same position a little above the middle of the ascus,
for example in the nuclei of Xylaria polymorpha, Nectria, Sphaeria obducens,
Curcurbitaria Laburni, Pleospora herbarum, Sordaria fimiseda, De Not., and some

CHAPTER III.—SPORES OF FUNGI. 79
%

others. The contents of the asci in most of the Pyrenomycetes which have been
examined show only the yellow coloration of protoplasm with iodine; but the
glycogen reaction is beautifully shown in Sphaeria obducens during or even before
the formation of the spores, and in Pleospora herbarum, Sordaria fimiseda, and Sphaeria
Scirpi after their formation. All these facts tend to show that the developement of
the eight-spored asci in the Pyrenomycetes is essentially the same as in the Discomy-
cetes, and that further observations will confirm this view.

The eight-spored asci of Podosphaera Castagnei have a large nucleus in the young
state ; this subsequently disappears, and the spores which are formed simultaneously
have very distinct central nuclei and are imbedded in a glistening glycogen-mass.

Nuclei were found also by Fr. Schmitz in the asci and spores of Exoascus Pruni ;
in other respects the development of the spore is entirely the same in this species
as in the Discomycetes (see also section LXXVI).

Thenumber of primordia of spores laid down in the typically 8-spored asci is very
constant; exceptions are comparatively rare, such as that of 9 spores in Cryptospora, Tul.
and in Exoascus, and 13 developed normally in a single ascus of Peziza melaena. It
more frequently happens, especially in the Pyrenomycetes and Lichen-fungi and accord-
ing to Boudier in Ascobolus also, that some of the 8 spore-primordia remain unde-
veloped ; most of the cases in which less than 8 spores have been found in species
in which that is the typical number, may probably be thus explained. The abortion
of individual spores is almost always an accidental phenomenon ; it occurs regularly,
according to Tulasne’s account’, only in Collema cheileum, where the mature ascus
always (?) contains aborted as well as perfect spores, the aborted ones adhering irregu-
larly to one another or to the perfect spores.

A larger or smaller number than 8 is the typical number of spores in the asci
of some Ascomycetes; 1-2 for example in Umbilicaria and Megalospora, Mass. ; 2 in
Erysiphe guttata, Pertusaria sp. and Endocarpon pusillum; 4 in Erysiphe sp. and
in Aglaospora profusa; 16 in Ascobolus sexdecimsporus, Crouan?, Hypocrea rufa,
P., H. gelatinosa, Tode, H. citrina, Tode, H. lenta, Tode, &c.’; 40, 50 and more in
Diatrype quercina and D. verrucaeformis, Calosphaeria verrucosa, Tul., Tympanis
conspersa, Fr., and T. saligna, Tode; the genera Bactrospora, Acarospora, and Sar-
cogyne of Massalongo have over 100 spores, most species of the genus Sordaria *
have 8-spored asci, but in some the asci have 4, or 16-64, or even 128 spores. In
some species again the number varies; the asci of Dothidea Sambuci, Fr. produce
2-4 spores, those of Erysiphe sp. and Pertusaria sp. 4-6, Sordaria fimiseda 4-8, S.
pleiospora 16-64, and others might be mentioned ; in Tuber the number of spores
varies as much as from 1-6, and in Elaphomyces from 1-8. The history of the
development of these asci has not been so accurately studied, if we except the asci of
the two last genera, as that of the typically 8-spored asci; still all that is known of
it and of the spores themselves, especially their simultaneous appearance, agrees with
the account which has been given of the 8-spored genera. The genera nearest allied
to these often have asci with 8 spores, Erysiphe for example, Diatrype, Aglaospora
and Calosphaeria; and asci with 4 as well as 8 spores occur in some species of
Sordaria and in Valsa ambiens, V. salicina and V. nivea, some in the same, some
in separate perithecia. Hence it may very well be presumed that the formation

1 Mém. sur les Lichens. See the literature cited at close of section LXXIV.
2 Crouan in Ann. d. sc. nat. ser. 4 (1858).

3 See Currey in Trans. Linn. Soc. London, XXII.

* G. Winter, Die deutschen Sordarien, Halle, 1873.

80 DIVISION I.-—GENERAL MORPHOLOGY.

of spores in these instances differs from that in the 8-spored asci in no other respect
than in the number of nuclear divisions and spore-primordia. Whether regular
abortion of a certain number of original spore-primordia occurs in individual cases,
where the number of perfect spores is small, is still uncertain. The formation of the
spores too in Tuber and doubtless also in the rest of the Tuberaceae and in
Elaphomyces differs much less from that in asci with 8 spores than appeared from
my former observations, which were conducted with imperfect means. There also
we find simultaneous orientation of spores and nuclei. The inequality in the number
of the spores is due partly to the inequality in the number of the original spore-
primordia or divisions of the nucleus, partly to the frequent want of uniformity
in later developement and to the partial disappearance of spores after they are once
formed.
In the full-grown stalked spherical ascus of Tuber (T. aestivum, T. melanosporum,
T. brumale (Fig 40) and their allies) the protoplasm which is at first irregularly granular
and interspersed with vacuoles becomes differentiated into a dense parietal strongly

refringent layer of glycogen, which turns a brownish red with iodine, and an excentric
spherical cavity filled with finely granular weakly refringent protoplasm which becomes

FIG. 40. Tuber brumale, Vitt. Full-grown asci isolated in water. @ p lasmic cavity d from the layer
of glycogen. 6 six young spores visible in the protoplasm. c shows one spore half matured and two which have remained
quite small in the same position. Magn. 390 times. 7

yellow with iodine. The limiting layer of the glycogen-mass is very compact where it
borders on the cavity, and its double contour is often so sharply defined that older
writers supposed it to be the membrane of a special cell. The spores are formed
in the protoplasm. Observations made by Errera have shown that there is one
nucleus in the protoplasm, visible even in younger asci, which by successive
divisions gives rise usually to 4-6 nuclei; then as many spore-primordia appear
simultaneously and in close proximity to one another round these nuclei in the form
of small and very delicate cells. As the cells now begin to grow they move further
apart and usually develope unequally, some outstripping the others, while some remain
stationary at an early stage of development and at length disappear. Hence the
frequent occurrence of quite delicate spore-primordia with others that are far advanced,
which once led me to suppose that they were formed successively, and hence also
the unequal number of ripe spores, varying from 1-4-6 in an ascus. The old drawings
reproduced in Fig. 40 will sufficiently illustrate the subject for the present.

The asci of Elaphomyces granulatus are of similar form to those of Tuber, and
contain before the orientiation of the spores a very transparent protoplasm forming
a thin parietal layer round one or more vacuoles and turning yellow with iodine; no
glycogen-mass appears in them. I found in the lower third of a half-developed ascus
where the great increase in breadth begins, a small but distinct nucleus with the

CHAPTER III,—SPORES OF FUNGI, 81

structure of that in Peziza confluens ; I could not see it in the ascus when fully formed,
but the young spore-primordia on the other hand have a distinct nucleus. The spores
lie close together and form a small group of usually six small round delicate cells, which
occupy the apex or a part of one side of the ascus; they are all alike when quite young
and were probably therefore formed simultaneously, but they develope very unequally ;
the mature asci contain from one to eight, usually six spores.

c. The formation of spores in the sporangia of Protomyces macrosporus
(Fig. 41), if the expression is allowable in this case, takes place after they are laid on or
in water. Before the water makes its way into them they have experienced complex
changes, which cannot be further described in this place, and have assumed the form of
spherical vesicles (Fig. 41 5) the walls of which are lined with a layer of dense
granular protoplasm (c) enclosing a large central cavity filled with water. No nuclei
have been seen in them. The layer of protoplasm now breaks up simultaneously all

“round the cell usually into hundreds of ‘spores’ (d), which when the separation is
complete are small polygonal finely granular bodies parted by narrow hyaline streaks,

d

FIG. 41. Protomyces macrosporus, Unger. a mature resting-spore in the dormant state (see section LIII) with the remains of the
hypha on which it was formed. 5 further development when cultivated in water; the protoplasm enclosed in an inner layer of the
membrane (inner cell) swells up and escapes from the ruptured outer layers of the c—ed of the spores inthe
inner cell (: i which has ped from the outer cell. Inc the protoplasm is parietal. In @ the protoplasm is divided into spores.
Ine the spores form a cluster and are separated from the layer of protoplasm which still lines the wall. Magn. 390 times.

and presently assume the form of small cylindrical rods about 2.2 y in length.
The differentiation in the protoplasm described in my work quoted in section LIII as
preceding the partition requires fresh examination. A granular parietal layer of
protoplasm which permanently clothes the membrane and a small portion of hyaline
substance between the spores, possibly of the nature of protoplasm, is not employed
in the formation of the spores. The latter substance becomes visible, when the spores
have taken the form of rods and have collected into a ball (e) on one side of the
wall of the sporangium, as a series of radiating threads running from the ball of spores
to the wall-utricle; but by degrees it disappears entirely and a watery fluid takes
its place.

Section XX. The spores which are produced endogenously are usually
set free from their mother-cells in some determinate manner as soon as they are
ripe and fully grown. In a few cases, as in Elaphomyces, Eurotium and perhaps in
Penicillium, they escape from the mother-cell before they have acquired the size and
structure which usually precede germination, and they subsequently attain to these at the
expense of dissimilar cells which had surrounded the sporangium. In extremely rare

L4] G

82 DIVISION I.—GENERAL MORPHOLOGY.

and exceptional cases the release of the ripe spores is left to chance, there being no
special arrangement made for it, and the spores may even germinate inside the mother-
cell, the germ-tubes piercing or bursting through its wall, as may be seen in the
sporangioles of Thamnidium and its allies.

The arrangements for the escape of the spores vary in different species.

a. The aquatic swarm-spores of the Saprolegnieae (with one partial exception to
be noticed hereafter), of the Peronosporeae and Chytridieae make their exit through
a narrow orifice, formed usually at the apex of the wall of the mother-cell by the sudden
swelling and disappearance of a circumscribed portion of the wall of the mature
sporangium. The spot is marked out in many species by gelatinous thickening
of the membrane before it begins to swell. This is nowhere more conspicuous than
in the sporangia of Phytophthora, in some species of Peronospora, and in some of the
Chytridieae which have gelatinously thickened terminal papillae; in other cases, as
Saprolegnia, the thickening has not been observed. While the place of exit swells,
the entire contents of the sporangium, the mass of spores and the surrounding matter,
absorb water and also swell!; and as the lateral walls of the sporangium are but
slightly extensible, the spores which lie beneath the place of exit are first squeezed

out through it and the others follow.

rf The proceeding may vary in individual

Qs ‘a cases, and it remains for investigation

f to determine to what extent the spores

@ themselves, the intermediate parting

substance (see p. 74) and perhaps also

an inner layer of the wall of the spor-

angium, participate in the first general

ie, pttors nn swelling caused by the absorption of

See rae erence moin: <eesnecome water, In the cases which have been

more carefully examined (Achlya, Sap-

rolegnia and Phytophthora, Fig. 42) it can be seen directly that it is the hyaline substance

surrounding the spores inside the firm wall which swells the most. Itis also observed

in most cases that a hyaline layer on the inner surface of the firm wall first comes

into prominence, and increases in breadth and pushes the mass of spores towards the

middle of the sporangium and the place of exit. The spores, even where as in some

cases they show independent movements before they are set at liberty, are now

virtually passive, and in Achlya especially they are evidently squeezed together as

they escape from the sporangium by the limpid mass which surrounds them. It is

therefore in the swelling of this mass that the expelling force resides ; but it is still

uncertain whether the mass consists entirely of the original soft partition-layers which

must in that case suffer partial dislocation when the spores are discharged, or whether

an innermost layer of the wall of the sporangium swells and some product from the
spores themselves is also added.

The phenomena connected with this swelling at the place of exit occur only at
a given moment after the formation of the spores is completed, and in water more-
over which is perfectly pure and contains free oxygen. That the point of exit, which

1 Walz, Bot. Ztg. 1870, p. 689.

CHAPTER III.—SPORES OF FUNGI. 83

has in many cases been formed some time before and gelatinously thickened,
does not swell in the water before this moment must be due to its not having yet
undergone the change which takes place in it after the spores are matured, supposing
both phenomena to have a common cause or the cause of the change to lie in the
Tipe spores. In the latter which is the more probable case we are almost compelled to
suppose that some secretion must proceed from the spores, which acts as a ferment
altering and dissolving definite portions of the wall which had been previously
prepared. The same view will apply with slight modification to the substance inside
the persistent firm wall of the sporangium which is capable of swelling and takes an
active part in the expulsion of the spores, and to the discharge of the zoospores of
many of the Algae.

On the special features in the formation of the zoospores of Pythium, the
formation of small heads in Achlya, Aphanomyces and Achlyogeton, and the coating
of the spores in these genera and in Dictyuchus, which cannot be further described
in this place, see section XL and the special literature there cited.

6. The upper and largest portion of the outer wall of the spherical sporangia of
Mucor (including Thamnidium, Rhizopus, Absidia, Phycomyces, &c) and Mortierella
is changed when the spores are ripe into a substance which dissolves in water, and in
most of the mucor-forms is incrusted with a thin spiky coating of calcium oxalate.
The presence of the smallest quantity of water causes the wall and the substance
between the spores which is present in greater or less abundance to dissolve and
liberate the spores (see p. 75). The lower portion of the outer wall which surrounds
the point of insertion does not participate in these changes and remains after the
dissolution of the rest of the sporangium as a ring or collar round its insertion; the
basal wall is also persistent and forms in Mucor the strongly convex or even
vesicular structure known as the columella.

In the allied genus Pilobolus‘the sporangium has at first the shape and structure
and even the oxalate incrustation of that of Mucor. The upper and larger portion of
its outer wall is very firm and of a bluish black colour; a comparatively narrow
annular zone round the point of insertion is more delicate and colourless. The mass
of spores contained in the sporangium is at first surrounded, especially at the point
of insertion of the sporangium, by a colourless gelatinous layer lying between the
spores and the wall, and endowed with great capacity for swellingin water. This layer
appears to be developed to a greater or less extent according to species, but whether
it is originally a part of the wall of the sporangium or formed like the spores from
the contents of the sporangium is at present uncertain. If water reaches the thin
basal zone of the outer wall it penetrates through it and causes the gelatinous layer
which lines it to swell up at once, and the wall of the sporangiüm is consequently
ruptured round the point of insertion and carried upwards by the continuously
swelling substance. It is not known whether the membrane is still intact when
the water makes its way through it, or whether fissures for the admission of the water
are previously formed in it as the result of changes of form and varying moisture
after maturity. In species like Pilobolus anomalus, Ces. (Pilaira, v. Tiegh.) with
very long filiform sporangiophores, nothing further happens beyond the gradual
solution of the gelatinous layer and the breaking up of the mass of spores; but in
most species (P. crystallinus, P. oedipus, &c.) the ripe sporangium is abjected from

G 2

84 DIVISION T.-—GENERAL MORPHOLOGY.

its sporangiophore and adheres by means of the gelatinous layer to foreign bodies,
while the spores swell to their full extent and are disseminated. The sporangio-
phore in these species! is a cell some millimetres in length, cylindrical in its middle
portion, but inflated in its lower part and in its upper part especially just beneath
the sporangium. It becomes more and more turgescent after the spores have
matured and causes abjection of the sporangium by means of the mechanism
described on page 72. The separation takes place in the line of an annular fissure,
which is close beneath the insertion of the outer wall of the sporangium and is seen
before the sporangium is flung off as a fine sharply marked line on the wall (Fig. 38).
The delicate wall of the lower portion of the sporangium is ruptured at the moment
of abjection, being struck by the ejected fluid, and thus the swelling of the gelatinous
layer investing the spores is secured.

The sporangium is sometimes abjected with considerable force. The sporangia
of Pilobolus oedipus, in which species, according to Coemans and Brefeld, the greatest
amount of force is exerted, are thrown, as we learn from the former authority, to a height
of more than 1.05 M. The process, as Coemans has also proved, is greatly
dependent on the amount of light. Under favourable circumstances the development
of the sporangiophore begins at midday or in the afternoon ; it is completed and the
sporangia and spores are also formed during the night, and the sporangium is thrown
off during the following morning at an earlier or later hour according to the greater
or less amount of light. Exclusion of light does not entirely prevent abjection but
may delay it 12-15 hours. P. oedipus shows this sensitiveness to light and the
normal periodicity to a less extent than P. crystallinus. We must not enter further
in this place into the connection between these phenomena and the very strong positive
heliotropism of the sporangiophore.

The increasing turgescence of the sporangiferous cell before abjection, assuming that
the superficial extent and elasticity of the membrane remain the same, may be
caused either by increasing osmotic absorption of water on the part of the sporangiferous
cell itself, or by the forcing of water from the mycelium into the passive sporangiferous cell,
or by the combined operation of both these agencies. In my first edition I assumed
that the latter of the two was the only operative cause, because a drop of water which
increases in size is often seen to issue after abjection from the open sporangiferous cell
before it finally collapses. More exact measurements are required for the confirmation
of this view.

Section XXI. The spores produced in asci and those of Protomyces
macrosporus are set free in one of two ways according to the species; either by
ejection ® (Ausschleuderung, Ejaculation) or by solution or gelatinous swelling (Auflösung,
gallertige Verquellung) of the asci.

The first process, the process of ejection, is found only in the case of spores
which normally attain their full development inside the ascus. As they advance:
towards this state, the protoplasm around them and the glycogen-mass subsequently
formed constantly diminish in quantity, being doubtless used to a great extent as
material for the formation of the spores. We are not at present in possession of more

! Coemans in Mém. conc. de l’Acad. royale de Belgique, XXX.—J. Klein in Pringsheim’s
Jahrb. VIII, p. 305.—Brefeld, Schimmelpilze, I and IV.—Van Tieghem, Mucorinées. See also the
literature cited in sections XLI-XLIV.

2 ‘Abjection’ and ‘ ejection’ have been adopted as renderings of ‘Abschlenderung’ and ‘ Ausschleu-
derung,’ the throwing off or throwing out with force of spores from the sporogenous structure.

CHAPTER III—-SPORES OF FUNGI. 85

exact knowledge on this point. When the spores are ripe a considerable quantity of
protoplasm richly interspersed with vacuoles still remains in some species, as Sphaeria
Lemaneae!, S. Scirpi and Sordaria fimiseda; in most cases, however, the residue is
but scanty, but in all without exception the inner surface of the membrane is covered
by an unbroken though often very thin layer of protoplasm. The chief portion of the
contents of the ascus surrounding the spores consists of an apparently watery fluid.

The membrane, which when young is always delicate and not stratified, increases
in thickness as the ascus matures, but often shows no signs of being divided into
layers even in such large asci as those of Morchella esculenta, Peziza Acetabulum,
P. pitya, P. melaena, and Ascobolus furfuraceus; in some species, especially in Lichen-
fungi, it is distinctly stratified, and in a number of cases, which will be noticed more
fully below, it has peculiar local thickenings at the apical extremity. It shows the
reaction of Fungus-cellulose in most Fungi; yet a dilute solution of iodine produces a
blue colour in not a few cases, either over the whole of the ascus, as in most Lichens
and in Peziza convexula, P. cupularis and others’, according to Coemans in some
species of Ascobolus also, or only at the apex of the ascus, as in some instances which
will be considered at greater length in the sequel.

The ejection of the spores from the asci is either simultaneous or successive.

The simultaneous ejection of spores is much the most common, occurring in
nearly all the Discomycetes, in the Erysipheae, in some Sphaeriaceae and in the sporan-
gia of Protomyces. Certain special modifications are said to occur in Lichen-fungi and
will be noticed again further on; but except in these cases the ejection of the spores
is due to the same mechanical arrangement as that which causes the abjection of the
spores and sporangia of Empusa or Pilobolus. It has been carefully observed (with the
exception of the case of Protomyces which must be at present disregarded) in club-
shaped or ovoid asci which are broader towards their free extremity and contain four,
eight, sixteen, or more rarely alarger number of spores. After the spores are matured
the ascus with its parietal layer of protoplasm enclosing a constantly augmenting
quantity of watery fluid expands considerably and becomes more turgid. The
expansion may amount to five-fourths or four-thirds or even to twice or several times
the original diameter of the ascus, i.e. the diameter at the time of the ripening of the
spores, and takes place in the direction of the length as well as the breadth, affecting
especially the upper and apical portion of the ascus. That the membrane of the
ascus is almost entirely passive in this extension and continues to be perfectly elastic
may be proved at any time by cutting it through or by extracting the water.

When the ascus begins to expand the spores move into its apical region, where
they are closely packed together in the watery fluid and in the simplest and most
common case are arranged in a single longitudinal row, the uppermost member of
which is close beneath the apex; it is more unusual for them to form two or more
irregular rows, as in Ascobolus and its allies. In some cases gelatinous appendages
which will be described by-and-bye, serve apparently to keep the spores in their
relative positions in this arrangement or at least to assist in doing so*. According to

1 Woronin, Beitr. III.

? See also Nylander in Flora, 1865, p. 467.

3 Zopf in Sitzgsber. d. Berliner naturf. Freunde, Feb. 17, 1880. Zopf’s last work on this subject
(Zeitschr. f. Naturaw. 56, Halle, 1884) could not be consulted.

86 DIVISION I,—GENERAL MORPHOLOGY.

Zopf the uppermost spore in some Sordarieae is even attached to an inwardly directed
process from the membrane at the apex of the ascus. No such arrangements have
been observed in the majority of cases, and the apical position of the spores is
sufficiently explained by the consideration that the one-sided expansion of the apical
region must produce currents in the contained fluid in the direction of the apex,
which must push the spores suspended in it towards this expanding apex.

When the wall has reached a fixed maximum of extension, it suddenly gives
way at a point of least cohesion near the apex, which is the poznt of dehiscence; at
the same moment the elastic lateral wall contracts to the size spoken of above as the
original size, and the apical portion of the fluid contents together with the group
of spores is driven out through the fissure. Then the open ascus collapses and
perishes.

The arrangement of the spores in the apical portion of the ascus before their
ejection, when there are no special arrangements for attaching and securing them, is
evidently the result of the conditions of space and form. In many Discomycetes for
instance the spores are ellipsoidal or elongated, and their length greater than the
breadth of the ascus ; they lie therefore parallel in the ascus, in a single longitudinal
row close behind one another, each placed obliquely and touching the wall of the
ascus with both ends, the uppermost one having its upper extremity close to the apex
(Figs. 39 w and 43). Ifthe breadth of the ascus is much greater than the diameter
of the spores the arrangement is more irregular; thus there is an irregular longitudinal
row in Ascobolus pulcherrimus', two such rows in many Ascoboli”? (Fig. 45), and an
irregular ball crowded up into the apex of the ascus in the eight-spored asci of
Exoascus Pruni® and in the many-spored asci of Ryparobius“. But the longitudinal
arrangement is maintained in the comparatively very broad asci of Sordaria (Fig. 44),
where it may be due to the attachment.of the spores to one another.

The form of the fissure varies with the species, and it cannot always be distin-
guished with certainty.

A longtitudinal rent simple or lobed, passing over the apex and leaving a broad
hole when the ascus is emptied, forms the opening in the asci of Exoascus Pruni,
Peziza cupularis and Erysiphe®, and according to Boudier * of Geoglossum, Helotium,
Leotia, and Bulgaria sarcoides.

In many Pezizas, as P. convexula, P. confluens, P. granulata, P. abietina,
P. vesiculosa, P. melaena, all the Ascoboli and Helvella crispa, the fissure is annular
and runs close beneath the blunt summit of the wall of the ascus, which is therefore cut
off like a lid, and when the spores are ejected is lifted off either all the way round or
only on one side where the uppermost spore touches the wall of the ascus; the
latter is the case, for instance, in Peziza vesiculosa and P. granulata. In larger
Ascoboli the edge of the lid may be seen before the ejection of the spores as a
distinctly marked transverse line”. In some forms, as P. abietina and P. vesiculosa,

1 Woronin, Beitr. II, t. III.

2 Boudier in Ann. d. sc. nat. ser. 5, X.

3 De Bary, Beitr. I, t. III.

* Bondier, 1. c.

5 R. Wolff, Erysiphe ; see the literature cited in section LXXIV.
® Loc. cit. p. 202. 7 See Boudier’s figures, 1. c.

CHAPTER III.—SPORES OF FUNGI. 87

it is the apical and most extensible portion of the wall and chiefly the area forming the
lid in that portion which is most distinctly coloured blue with iodine. In the
Sordarieae also I frequently saw the ascus open by a comparatively tall lid.

There is a third series of cases in which the spores are ejected through an apical
perfectly circular hole which before ejection of the spores is a circumscribed thinner or
less compact portion of the wall of the ascus. In Rhytisma acerinum this hole is
replaced by a minute mucro forming the uppermost extremity of the apex of the still
closed ascus. In Peziza Sclerotiorum (Fig. 43), P. tuberosa, and their allies, the wall of
the ripe but not turgescent ascus is more than twice as thick at the slightly convex
apex before the spores are discharged than it is on the sides; it is also formed of
two layers and is traversed in the middle by a longitudinal
streak which is less strongly refringent and looks like a
stopper inserted in the ascus. The apex of the turgescent
ascus, ready for the ejection of its spores, is considerably
broader and strongly convex outwards, with its wall not
thicker than the lateral walls and with none of the in-
ternal structure just described. The spores are discharged
through the stopper, and after the discharge there is an
open passage in its place round which the form and
structure of the non-turgescent state are once more
restored. In these cases again the apical portion of the
wall, which is most capable of stretching and is thickened
when it is not in a state of tension, is that which turns
blue with dilute solution of iodine, and the stopper which
indicates the point of dehiscence is most intensely
coloured.

The following remarks will further illustrate the above
short account of the mechanism for the ejection of the
spores.

a, The expansion of the ascus by increase inthe amount rıc.43. Peetea (Sclerotinia) Sclero-
. = > tiorum. Asci observed as they lay
of its fluid contents has been directly observed. That zen in water a@ a mature scan

this is merely a passive stretching of the cell wall, and before ejection of the spores. 6 the
A R same after ejection. c another specimen
not a phenomenon of growth with permanent results, is in the same stage of development as 2,
shown by facts which are easily observed, namely, that St meug» wansversely. Magn. about
the ascus contracts to its previous dimensions after dis-
charging its spores, or if an artificial opening is made in its wall while its membrane
at the same time increases in thickness, as is shown most clearly in the case of
the strong local thickenings which have been described as occurring in Peziza
Sclerotiorum. This species shows with peculiar distinctness that it is the apical
region of the ascus which stretches most; but in all other cases attentive comparison
will show that it is the apical region, or pretty well the apical half, which is most
altered in form and size while the lower half is little or not at all affected. The
directions of greatest extensibility and the shapes produced by them vary much
in different species, as appears from a comparison of Figs. 43,44 and 45. The enormous
increase in volume of the asci of Sordaria may perhaps suggest actual growth,
-especially as they are comparatively rich in protoplasm after the spores are matured ;
the point requires further investigation, but it should be noticed that the contraction
after the ejection of the spores is in this case also very considerable.
That it is the increase in the amount of fluid content which causes the expansion

88 DIVISION I.—GENERAL MORPHOLOGY.

of the ascus is shown by the fact, that the expansion diminishes with a diminution
in the amount of fluid in the cell and disappears, either suddenly and entirely, if the
wall of the ascus opens spontaneously or is pierced artificially and the fluid escapes,
or gradually through the slow operation of alcohol, glycerine, or saline solutions
which withdraw water from the uninjured ascus. On the other hand the expansion
of the asci (and ejection of the spores) is promoted by placing uninjured asci in water.

6. The great elasticity of the wall of the ascus is sufficiently shown by the facts
above enumerated. *

c. The spores are in many cases retained according to Zopf in the expanding
apex of the ascus by a special apparatus of attachment'. In Sordaria Brefeldii a
hollow cylindrical thick-walled process of the membrane, which turns blue with
iodine, reaches from the apex into the lumen of the ascus. The spores, like those
shown in Fig. 52, are provided with terminal appendages which connect them
together in a row; the distal appendage of the uppermost spore attaches the
entire row to the process from the wall of the ascus, ‘sometimes by thrusting itself
into its cavity which it fills up, sometimes by closely grasping it. And this apparatus
is further completed by another arrangement; the membrane of the ascus over a
subterminal zone is capable of great swelling and can lay firm hold on the appendage
borne by the chain of spores, as a hand grasps the throat.’ Similar apparatus may
perhaps frequently be in use especially in the Pyrenomycetes, as is indicated by
the structural features in the apices of asci which will be discussed in section XXVI.
Our present knowledge does not allow us to speak with certainty on this point.
In many cases, especially in the Discomycetes, there is no such apparatus present,
the spores being suspended in the fluid of the ascus. The spores must have nearly
the same specific gravity as the fluid; if not, they would change their position as
the ascus changes its inclination, which they do not do. Most, if not all, spores
produced in asci sink in pure water; the fluid contents of the ascus must therefore
be of greater specific gravity than pure water, since it holds in suspension bodies
of greater specific gravity than water. If increase in the amount of the fluid
contents causes the apical portion of the ascus to stretch more than the other parts,
currents must be set up in the fluid in the direction of the apex and continue as
long as the expansion continues, and push the spores therefore permanently towards the
apex. The arrangement of the spores may then be affected by special directions
in the currents which we cannot at present determine, as well as by the conditions
of space noticed above.

d. The ascus lined with a layer of protoplasm and preparing to eject its spores
is in the condition of a cell in a state of constantly increasing turgescence, the
characteristics of which may here be presumed to be known?. It is natural therefore
to suppose that the increase in the amount of fluid contents is caused by absorption
of water by endosmosis, and that this absorption is due to the operation of osmotically
active substances, dissolved in the cell-contents, which cannot pass through the layer
of protoplasm. All the facts that have been observed agree with this supposition,
and especially the circumstance that volume and turgescence can be alternately
diminished and restored in individual asci by careful removal of water by means
of a saccharine solution or of glycerine, and by its reintroduction. The opposite view
expressed in the first edition of this work was founded on the fact that the proto-
plasmic utricle in the asci which were examined was either injured or killed
in the process of withdrawing the water, and it has been shown that isolated asci
are very liable to suffer in this way. The presence of the substances which are active
agents in inducing endosmosis is evidently coincident with the disappearance of the

1 As cited on p. 85.
” Pfeffer, Pflanzenphysiologie, I, p. 50.—De Vries, Mechan. Ursachen d. Zellstreckung, Leipzig,
1877.

CHAPTER III.—-SPORES OF FUNGI, 89

residue of protoplasm or glycogen-mass as the spores mature. I was unable to
determine their character more nearly, and can now only state that neither sugar nor
any acid reaction was ascertainable in the fluid contents of the asci of Peziza granulata,
P. Sclerotiorum, and Ascobolus furfuraceus.

e. It is evident from what has now been said that, other conditions being the same,
the ejection of the spores must be hastened by a lateral pressure operating on the
ascus from without. This may readily be shown by experiment on isolated asci
placed in water beneath a cover-glass. In the living Fungi the asci stand very many
together in the hymenium usually with paraphyses between them, and there the
lateral pressure on the asci increases in part with the advancing growth, as new asci
are introduced between the previous ones, and in part with the addition of water ;
the hymenia in the Discomycetes which have paraphyses swell considerably in the
direction of their surface and in greater proportion than the tissue of their sporophores.

Jj. All that has been said of the club-shaped asci may be applied in its main points
to the spherical sporangia of Protomyces macrosporus, which are formed free in
the water. The place of greatest extensibility, towards which the numerous ‘spores’
move, is in accordance with the shape of the sporangia a broad thin section or pit
in the wall, in the middle of which the fissure ultimately appears as a gaping slit.

Section XXII. It has been already said that the asci of the Discomycetes
of which we now proceed to speak, are arranged in superficial hymenia nearly
vertically to the surface and between numerous paraphyses of uniform height,
the extremities of which indicate the middle level of the hymenial surface. The
asci of a hymenium are not developed simultaneously; during a period of time
which varies in different species new asci grow up one after another from beneath
between the paraphyses, while the older ones are ripening. When the asci approach
maturity and begin to enlarge each one elongates so much that its apex projects above
the surface of the hymenium, while its basal portion continues attached to the original
place of insertion. After ejection of the spores the ascus shrinks and the apex
usually returns to below the level of the hymenial surface. Where there are no
paraphyses, as in Exoascus, the same phenomena are observed with the modifications
which that difference naturally entails.

In the hymenia of Peziza, Helvella, Morchella, Bulgaria, Exoascus, and the ma-
jority of the Discomycetes when they are ripening, the individual asci are constantly
discharging their spores in succession. If the Fungus is placed in a closed and damp
chamber and a glass plate is set in front of the hymenium, spores are soon found lying
usually eight together in a minute drop of fluid, and gradually the plate becomes thickly
strewed with them. But besides this gradual emptying of the asci many of the Dis-
comycetes have the peculiar habit of ‘puffing’ (Stäuben), that is, of suddenly discharging
a whole cloud of spores, if they are shaken, or if the chamber in which they have been
kept is opened. The phenomenon is of course produced by the simultaneous
emptying of a number of asci. The Fungi on which my experiments „were
chiefly made—Peziza Acetabulum, P. Sclerotiorum, and Helvella crispa—do not
puff when they are cultivated in a very damp and still atmosphere enclosed by a bell-
glass; under these conditions only the continued gradual discharge of the spores
takes place. As long as the Fungus remains shut up in the damp atmosphere no
amount of shaking will cause it to puff, whether it is kept in the dark or in the
light of day, or is suddenly brought from the dark into diffuse or direct sun-
light; but it puffs as soon as it is removed from the damp chamber into a dry

90 DIVISION I.—GENERAL MORPHOLOGY.

atmosphere. If the hymenium is only moderately damp, so that the tips of the ripe
projecting asci look like a slight rime or a fine down on it, the puffing commences
in a few seconds after the bell-glass or other covering is removed. If it has been
kept very wet, the hymenium is covered with a thin layer of water and glistens more or
less and is of a darker colour than in the moderately moist condition. In such a
hymenium the puffing does not take place till the layer of water is evaporated and
the slight rime-like appearance is observed ; the puffing is accelerated by whatever
accelerates the evaporation.

From these facts it appears that sudden loss of water is the proximate cause of
the puffing. Since puffing occurs instantaneously in hymenia that are not wet, the
withdrawal of water as soon as dry air comes in contact with the Fungus cannot
produce it by causing a shrinking and contraction of the entire hymenium and a
consequent increase of the pressure on the asci from without. All this could not
possibly be brought about to any important extent in one or a few seconds of time,
and some simple experiments and measurements are sufficient to convince us that the
pressure which operates on the asci from without under long-continued desiccation is not
at first increased, and eventually decreases to a considerable extent, but that it increases
in proportion as the hymenium absorbs water.

The loss of water can only therefore cause the puffing by altering the state of
tension in each ascus, either by lessening the expansion of the lateral walls and so
increasing the pressure of the fluid contents on the place of dehiscence, or by lessening
the power of the place of dehiscence to resist the pressure which remains unaltered.
The correctness of this explanation is confirmed by the observation, that ejection takes
place when ripe isolated asci lying in a little water are suddenly exposed to the
operation of reagents like alcohol and glycerine which withdraw their water.

The above remarks leave little room for doubt that motion and shaking affect
the puffing only by hastening the evaporation of the water. A hymenium which
has just sent forth a cloud of spores can be induced to repeat the operation several
times, if the plant is moved rapidly to and fro, and the less perfectly ripe asci are
made to dehisce. But then, and in many cases after the first puffing, a rest of at least
some hours is necessary, that a sufficient number of new asci may come to maturity
to allow the puffing to be observed.

The phenomenon of puffing is absent from some Discomycetes; I have never
been able to excite it in Peziza pitya, Morchella esculenta, or Exoascus Pruni; it is
readily produced in the majority of species. I have observed it in Peziza melaena,
P. tuberosa, P. aurantia, P. cupularis, P. badia, P. confiuens, and Rhytisma acerinum, in
addition to the species which have been already named. Many other observations
have been recorded since the time of Micheli.

In Ascobolus and the genera which have been recently separated off from it
ejection is never successive but always simultaneous from all the asci that are at any
time ripe in the hymenium, and here too we have the phenomenon of puffing. The
mechanism of the discharge and the conditions for the puffing are the same as those
which have been described in the case of the other Discomycetes ; but they are also
dependent on the illumination to an extent which requires to be more closely
examined.

CHAPTER III.—SPORES OF FUNGI. 91

Section XXIII. The process of ejection in the Pyrenomycetes which discharge
their spores simultaneously was first correctly described in Sordaria by Zopf?.
Numerous asci placed upright side by side in a thick tuft fill the swollen enlarged
basal portion of a flask-shaped receptacle, the perithecium, which is continued upwards
into a more or less elongated neck. In large forms, as S. fimiseda, the neck is more
than a millimetre in length but much shorter in the smaller species, and is traversed
longitudinally by a very narrow canal, not so broad as an ascus, which enlarges into a
conical form at its inner end above the group ofasci and is open to the air above at the
outer end. Till the spores begin to ripen the asci are between narrowly cylindrical
and club-shaped, and of the same height as the basal
ventral portion of the perithecium. Then they begin to
elongate one after another while they grow much broader
at the apex. The only direction in which they can
elongate is that of the canal of the neck. When the apex
of the first ascus reaches the inner end of the canal, it
enters it and swelling there to a broadly club-shaped
form, and causing a corresponding enlargement of the
canal, it continues to lengthen, till its apex is on a level
with the outer mouth of the canal or a little above it;
then its ejection takes place. Then the next ascus enters
into the now empty canal, and so on one after another.
The lower extremity of the ascus continues attached to
its original point of insertion at the base of the peri-
thecium until ejection. The elongation is therefore very
considerable; in the case depicted in Fig. 44, for instance,
it is more than six times the length attained by the ascus
at the time the spores are ripe, and is at least three times
that length beneath the widened upper part. The lower
portion seems to become narrowed at the same time
under the pressure of the neighbouring asci which are a

FIG. 44. Sordaria minuta, Fuckel f}.
beginning to swell, but it is difficult to be quite certain on Form with 4spored asci; small perithe-

cium grown on a microscopic slide and

this point on account of the strong lateral pressing to- observed in the living state lying in the
culture-fluid, in optical longitudinal sec-

gether of the parts. tion; at the base of the perithecium is
ee M 2 5 a dense group of asci, most of them with
The rapidity with which the elongations are accom- ‘ire spores; above this group are other
3 " x a mature asci in various stages of elongation
plished is comparatively small. In a small specimen preparatory to ejection, the u
A having almost reached the opening of the
observed in water the movement of the apex about a neck. Magn. about 100 times.
spore’s length (= 17 x) occupied some 15 minutes, and
the passage through the whole neck about 8 hours. In the specimen of Sordaria
minuta (?) given in Fig. 44 the motion was quicker, a spore’s length of 10 » requiring
some five minutes. How far light, heat and other external causes accelerate or
retard the movement, and what are the specific differences which certainly exist,
are points which have yet to be investigated.

Section XXIV. The force with which the spores are ejected does not appear
tobe great. In Bulgaria inquinans and Protomyces macrosporus they are sent straight

1 As cited on p. 85.

92 DIVISION I.—- GENERAL MORPHOLOGY,

upwards to a height of 1-2 cm., in Exoascus Pruni of 1 cm.; in the strongly
- puffing Fungi, such as Peziza vesiculosa, P. Acetabulum, Helvella crispa, and Asco-
bolus furfuraceus, they are thrown to a distance of more than 4 cm., in Sordaria
fimiseda, according to Woronin, they travel 15 cm., in the smaller species of this genus
about 2 cm., in Rhytisma acerinum only a few millimetres. The movements in the
act of puffing in large hymenia were said by Desmazieres to produce an audible
sound, but this has been doubted by recent observers ; I have myself however heard
a very perceptible hissing noise produced by strong specimens of Peziza Acetabulum
and Helvella crispa.

The peculiar features in the old genus Ascobolus (including Saccobolus and others),
which led to many false and even strange notions, are connected with the large size
of the asci, the great prominence above the surface of the hymenium at the period
of maturity, and the regular periodicity in their ripening and in puffing’. Coemans
has given us a full account of how a number of asci ripen and eject their spores daily
for several days together, when the hymenium has reached
a certain point of development. The asci in consequence
of their expansion begin to appear above the surface of the
hymenium towards evening and continue to do so till
the succeeding afternoon; between 1 and 3 o’clock the
tension reaches its highest point, and the slighest shock
causes ejection which is simultaneous in all the projecting
asci. It is difficult to determine whether ejection takes
place when everything around is perfectly still. The still-
ness is in fact always broken by a number of younger asci
beginning to expand every afternoon in preparation for
ejection on the following day. It is natural to suppose that
there must be a direct relation between this regular daily
periodicity and the light-period, and Coemans found that
ejection was delayed 4-5 hours in the Ascoboli, when culti-
vated in darkness. Boudier and Zopf observed that the asci

FIG. 45. Ascobolus furfuraceus, P. = aes 5 A .
Portion of a section through the hy. are to a high degree positively heliotropic when they are in
menium; AX the upper surface ofthe process of expansion ; their curvatures towards the source of

hymenium shown by the extremities of the i
paraphyses #, @ young ascus, 6 nearly light may extend through nearly 90°, but these curvatures

ripe ascus projecting above A—#, e a a R

similar one which discharged its spores almost, if not quite, entirely disappear after ejection or

during the observation and contracted » . . Be ”

with an open lid at the apex. Magn. if the expansion is artificially stopped. The connection

195 times. between all these points requires more exact investi-
gation.

When the asci are ready to eject their spores they are very much extended and
their broad club-shaped apex rises considerably above the surface of the hymenium;
this led to the erroneous idea which was reproduced by Boudier, that the asci became
detached from their point of insertion and wandered up between the paraphyses ; they
really remain firmly attached, as in all the rest of the Discomycetes (Fig. 45). The
projecting asci moreover are distinctly visible to the naked eye in the larger species
as dark points, by reason of the dark violet-coloured spores in their apices. These
points disappear at the moment of dusting, because the spores fly off and the empty
tubes are drawn back beneath the surface of the hymenium. Older observers were
led by these appearances to the mistaken notion that the entire asci were ejected from

the hymenium, and hence the name Ascobolus.

? Crouan in Ann. d. sc. nat. ser. 4, VII (1857), p. 175.—Coemans, . Spicilége, I (Bull. soc. bot.
Belg. I, 1).—Boudier in Ann. d. sc. nat. ser. 5, X, p. 191

CHAPTER III.—SPORES OF FUNGI. 93

Section XXV. In most Lichen-fungi with open hymenia the mechanism for
the ejection of the spores is similar to that which has now been described, though it
differs from it in particular points which appear to me to require further investigation.
The structure of the hymenia is essentially the same as in the Discomycetes ; there
is, according to Tulasne, the same turgescence of the mature ascus in both, and the
same simultaneous ejection through one or more longitudinal fissures in its apex’.
The asci are emptied one after another as they ripen, and the spores, according to
Tulasne, are flung outwards to a distance of about one centimetre; the sudden discharge
of many asci at once has not been observed. The differences alluded to above are, that
the apices of the asci do not project above the surface of the hymenium but continue
on a level with it or a little beneath it, and that the pressure on the asci from without
appears to be a chief cause of the bursting of
the asci and of the ejection of the spores.
The ejection of the spores is in fact due to
the action of water, which causes a con-
siderable swelling throughout the gelatinous
hymenium in the direction of its surface, and
consequently a lateral pressure on its turges-
cent asci. The pressure is moreover increased
by the resistance which is offered to the
superficial enlargement of the hymenium by
the thallus which bears it, and which has less
capacity for swelling by absorption of water,
or by special thallus-margins or excipula
circumscribing the hymenium, which, as
Tulasne has shown, bend in such a manner
when they absorb water, that they directly
oppose the enlargement of the surface of the
hymenium. Ejection of spores from an ascus
withdrawn by isolation from the influence of
these pressures, such as easily occurs in other
Discomycetes, has never been observed, so
‘far as I know, in any Lichen-fungus. FIG. 46. Sphacria Scirpi. A the ascus after elongation

with the ruptured outer membrane at the base and the
= } a 7 j spores not yet ejected. 3 the last spore of an ascus
With regard to the Lichen-fungi which spars net vst ciected._ the last spore of =
5 = 4 7 ejected are immediately above it. C ascus emptied of its
have perithecia, we only know that ejection spores. From Pfeffer's Physiology, after Pringchein.
from their asci also takes place?, but the

mechanism has not been properly investigated.

Section XXVI. Successive ejection. An isolated mature ascus of Sphaeria
Scirpi is a broad short club-shaped body, as Pringsheim first showed *, almost entirely
filled by its eight large spores, which are crowded together in two irregular rows. It
has an apparently homogeneous moderately thick wall with a double contour and
lined with a layer of protoplasm. Ejection takes place under water. Before it

1 Tulasne, Mém. sur les Lichens (Ann. d. sc. nat. ser. 3, XVII).
? Tulasne, 1. c.—Stahl, Beitr. z. Entwickelungsgesch. d. Flechten, II, 1877.
3 Jahrb. I, 189.

94 4 DIVISION I.—GENERAL MORPHOLOGY.

begins an extremely thin lamella of the wall, not previously distinguishable, suddenly
splits off at the apex of the ascus, and the inner lamella issuing through it lengthens
in a few seconds into a tube nearly three times’as long and as broad as or broader
than the original ascus; the lower part of the tube continues to be attached to the
torn outer lamella (Fig. 46 A). The wall of the elongated tube is of about the same
thickness as that of the original ascus-wall. The eight spores follow pari passu
the apex of the elongating tube, keeping as nearly as possible their original grouping,
the uppermost one being close to the apex. ‘Soon the uppermost spore is seen
to have moved into an aperture which has formed in the terminal point of the tube
and then to be ejected through it with great force. As soon as this has happened,
the tube shortens by about half the length of a spore, so that the second spore
now touches the point of the tube and is pressed into the aperture, which it stops
up. Then the tube elongates again to its original length and the second spore
is then ejected with the same force as the first. The entry of all the remaining
spores into the opening and their successive ejection is accomplished in the
same manner. Finally the empty tube, which is open at the apex, contracts rapidly
to about 3 of its length while the membrane continues to swell considerably, and
eventually becomes disorganised without undergoing further changes. The whole
proceeding occupies only a space of a few minutes. It is evident that we have
in this case a modification of the discharging mechanism, the chief point in which must
be that the width of the apical aperture is too small for a simultaneous discharge of the
spores ; but the question requires further investigation.

Successive ejection is at present certainly known only in a few Pyrenomycetes.
That it should occur also in the open hymenia of Discomycetes is not probable; a
brief statement of Crouan! about Vibrissea can scarcely be used here, and moreover
needs confirmation. In the Pyrenomycetes with which we are concerned here the
asci, like those represented in Fig. 44, are packed close together at the bottom
of perithecia with a narrow canal-like orifice, and when they elongate they thrust them-
selves one after another through the canal without becoming detached from their
insertion till their upper extremities are free from the perithecium, and then ejection
takes place. Woronin was the first who described these proceedings correctly in
Sphaeria Lemaneae?. His account holds good also of Sphaeria Scirpi, Phyllachora
Ulmi, and Cordyceps militaris. The tops of the asci may be seen emerging one after
another from the ripe perithecia of the latter species in a damp atmosphere, and
ejecting their spores. Each rises about six times its own diameter above the mouth
of the perithecium; in a few minutes the slender filiform spores fly one after another
with the speed of an arrow from the tip of the ascus; each of these successive
ejections is followed by a slight but permanent shortening of the ascus, which
reaches the level of the orifice of the perithecium as the last spore is ejected.

The ejection of spores from the perithecia of Claviceps, which was observed
by Tulasne® and may be seen with the naked eye as a puffing out of fine minute
glistening needles, is undoubtedly produced in the same way as in Cordyceps, and my
explanation of it at page 145 of my first edition was in the main incorrect. It would
appear from the accounts which we possess that the same or similar processes are

1 Ann, d, sc. nat. ser. 4, VII, p. 176. 2 Beitr. III, p. 5. ® Carpol. I, p. 42.

CHAPTER III.—SPORES OF FUNGI. 95

common in the Pyrenomycetes, but further investigation of individual cases is
desirable.

The last remark specially applies to a considerable number of Pyrenomycetes, in
which the asci have the same structure as in Sphaeria Scirpi and S. Lemaneae and
elongate in the same way if they are placed singly in water when they are mature ;
among these are Sphaeria inquinans and S. obducens, Schm., Cucurbitaria Laburni, and
some species of Pleospora!. See Fig. 47.

In all these species the membrane of the ascus consists of a thin outer layer with
little power of swelling, and an inner soft gelatinous layer which swells to an unusual
extent in water. If a ripe ascus is placed in water, the inner layer swells and breaks
through the outer layer and protrudes in the
manner described in the case of Sphaeria
Scirpi. When the ascus is intact the inner
layer is thin as compared with the cavity
of the cell and appears to be tightly pressed
between the unyielding outer layer and the
protoplasmic utricle, which is tensely filled
with fluid contents. As soon as the pressure
upon it is relieved by the bursting of the
ascus, it swells to such an extent in the
direction of the longitudinal axis that the
lumen is contracted into a narrow canal and
the contents, whether spores or protoplasm,
are driven out through the fissure. This
happens in fully developed asci which are
nearly mature, and in young half-grown asci ;
in both the membrane in the uninjured state
is thin as compared with the wide lumen.

In these species the ejection of the spores
is rare, though it has been observed ; the asci
when placed in water swell up at once, even
after elongation, into a clouded gelatinous
mass. This may be chiefly due to the fact
that the asci of these land species which swell
so readily have always been examined under
very injurious conditions, in sections, for in-
stance, or as crushed specimens suddenly
placed in water, and not in theirnormal state Auch "rn the werithechm weh Coameund plore
—a treatment which the asci of Sphaeria cellular spores. 5 the same after being placed in water,

Se R 2 theinner b being and the outer rup d
Scirpi and S. Lemaneae which grow in water In this specimen the spores were ejected in the same way

would be better fitted to endure. But the ee ieee sei
same remark applies also to other asci which

do not suddenly elongate when isolated in water, as appears from the case of Cordy-
ceps; these and many others when isolated and immersed in water show more or
less rapid gelatinous swelling of the walls of the asci.

Some of the asci of which we are speaking have characteristic thickenings
on the apical portion of their walls; in Cordyceps, Claviceps, and Epichloe typhina
the apex is thickened and becomes a nearly cylindrical body, almost as long as
the breadth of the ascus, pierced longitudinally by a very narrow canal, and set
like a lid or cork on the thin lateral wall. If we recall to mind the thickened apex

1 Tulasne, Carpol. 1. c. and II, t. XXVIII,’ &¢.—Currey in Microscop. Journal, Vol. IV, p. 198.
—Sollmann in Bot. Ztg. 1863:

96 DIVISION I.—GENERAL MORPHOLOGY.

as it was described in Peziza Sclerotiorum, &c. (Fig. 43), which is extended
by stretching into a thin membrane, it becomes a question whether the thickenings
in the cases we are considering are not extended in the same way into thin membranes
with the expansion of the ascus, and are to be considered therefore as reserve-pieces
of membrane destined to be extended and to assist in the ejection of the spores, and
comparable with the ring of cellulose in the vegetative cells of CEdogonium ; the
matter at least deserves inquiry.

Thickenings of the apex such as those that have been described occur also in
the asci of many Pyrenomycetes, in which ejection has never been observed. With
these may be specially mentioned the conical projection in species of Rosellinia
which has been recently examined by Crie!, but is better understood and described
by de Seynes?. In dried specimens of Rosellinia Aquila the cone is a cylindrically ovoid
body projecting from the apex into the interior of the ascus, longer than the breadth
of the apex of the ascus which it almost but not quite fills, and traversed by a narrow
longitudinal canal; in other words it is like a very thick annular ridge projecting from
the inner surface of the wall of the apex: it is coloured dark blue with iodine, as has
been often described. If the view expressed
in the case of Cordyceps is correct, it is a ques-
tion in the last-mentioned case also whether
the thickenings at the apex are not reserve-
pieces to assist in the ejection of the sporesand
destined to expansion. On the other hand,
from Zopf’s account of Sordaria Brefeldii
(page 88) we might ask whether they possibly
serve as means of fixing the spores in the apex
of the ascus. All this requires investigation,
in which each species must be separately ex-
amined, since ejection is by no means found
in all the Pyrenomycetes.

Section XXVII. Liberation of the
FIG. 48. SPA: A lloides, P. i, : Pi .
doneofthem more highly magnifed. canearlyripeseas, SPOres by solution or gelatinous swelling
d outline of an isolated ripe spore. outline of a similar
spore from which all but a small portion of thedark violet Of the wall of the ascus occurs, but not
episporium has been detached. 4 magn. about 700, all the = . .
rest about 390 times. frequently, in free open hymenia. It appears,
however, in the latter of the two forms to
be characteristic of the Discomycete Roeslaria hypogaea’. It occurs in the first
form, or with a disappearance of the ascus that cannot be more exactly defined, in
Sphaerophoron (Fig. 48), Acroscyphus, and the Calycieae, to which the genera
Lichina and Paulia which have perithecia are nearly allied, as has been shown
by Montagne‘, Fresenius®, and Tulasne®. The young spores in an early stage
are almost as broad as the narrow and delicate asci, and are arranged in a
single or in places in a double and uninterrupted row in the upper parts of
the ascus, from the wall of which they are separated by only a thin layer of

protoplasm (or glycogen-mass) a, 4. They now enlarge more rapidly than the

! Comptes rendus, 88 (1879), pp. 759, 985.

? Comptes rendus, 88 (1879), pp. 823, 1043.—R. Hartig in Unters.—d. forstbot. Inst. z. München
I, p. 20, t. II.

* Von Thümen, Pilze d. Weinstocks, p. 210.

* Ann. d. sc. nat. ser. 2, XV, 1841.

* Fresenius in Flora, 1848, p. 753.

° Mém. p. 77. See also Strasburger, Zellbildung u. Zelltheilung, 3rd ed. p. 54.

CHAPTER III,—SPORFS OF FUNGI. 97

ascus-wall which surrounds them, and the protoplasm disappearing they at length
entirely fill the cavity of the ascus; the wall of the ascus then forms a delicate septum
between each pair of spores, and not unfrequently appears constricted between each
pair c, but the septa are at length broken through in Sphaerophoron and most of the
Calycieae, and the spores are thereby set free from one another and are collected
together as a loose dust on the surface of the hymenium. In Lichina and Paulia the
spores remain firmly united together.

The phenomenon which we are considering is very common in asci which ripen
in closed receptacles. Chaetomium (Zopf) and Melanospora parasitica! may be
mentioned first as trustworthy examples among the Pyrenomycetes. In these species
the wall of the ascus swells when the spores are ripe into a copious jelly, which increases
in volume by absorption of water to such an extent that it issues out of the orifice of
the perithecium and brings out with it the spores which are imbedded in it. The
tissue surrounding the asci also swells up and adds to the quantity of jelly employed
in the way described. The mass of spores thus forced out of the perithecium collects
at its orifice in the form of drop-like aggregations or twisted tendril-like filaments like
a tough mass squeezed through a narrow tube. This mode of emptying of asci and
perithecia is very common in Pyrenomycetes with thin-walled asci, occurring probably
in species of Nectria®, in Hypoxylon concentricum, Nummularia, Stictosphaeria,
Eutypa, Quaternaria, and many other Xylarieae and Valseae described by Tulasne°.
But more exact observation of individual cases is still required with reference to the
considerations mentioned in this section. Perithecia without an orifice like those of
Chaetomium fimeti and Cephalotheca tabulata * burst by the swelling of the gelatinous
substance in a fixed manner.

The asci of Eurotium, Penicillium, Anixia truncigena®, Onygena, Elaphomyces,
and the Tuberaceae, which are also developed in closed receptacles but with no natural
aperture, and opening only in consequence of decay or some accidental lesion, are
dissolved or decomposed sometimes after temporary gelatinous swelling ; they disappear
entirely and allow the spores to enter free and unconnected into the cavity of the
receptacle.

Section XXVIII. The liberation of the spores takes place in almost all
cases as soon as they have reached maturity, that is as soon as they are fully devel-
oped, and this as arule precedes the commencement of germination. Inthe few excep-
tions to the rule, which are rendered more remarkable by its generality and apparent
necessity, the spores when they are liberated from the ascus increase considerably in
size either at the expense of their environment or of the reserve material which they
themselves contain, till they have reached the degree of development which strictly
corresponds to the state of maturity. Elaphomyces is specially noteworthy in this
respect‘, in which the spores, after they are set free from the perishing asci, grow to

1 Kihlmann, Zur Entw. d. Ascomyceten (Act. soc. Fennicae), XIII, 1883.

? Janowitsch in Bot. Ztg. 1865.

* Carpol. II.

* Zopf in Sitzgber. d. naturf. Freunde, see p. 85, and for Chaetomium, Nov. Act. Acad. Leopold
Bd. 42, Nr. 5 (1881).

5 H. Hoffmann, Icon. Analyt. III, p. 70.

° See De Bary, Fruchtentw. d. Ascomyceten, p. 33.

[4] H

98 DIVISION I.—GENERAL MORPHOLOGY.

about double their former size inside the general receptacle without any essential
change in their structure. A similar though less striking development is seen in
Eurotium, Sphaerophoron, and the Calycieae (Acolium ocellatum).

Section XXIX. Combinations of the different modes of formation and
shedding of propagative cells which have now been described bring about the appear-
ance of the bodies which are often known as sep/ate spores, but which it would be better
‘to term compound spores, sporae compositae. In their case a spore-mother-cell or
spore-initial-cell is developed either acrogenously or endogenously and then usually in
an ascus, and developes by means of one or several successive bipartitions with firm
partition-walls into a pluricellular body, in which each cell is an independent spore with
power of germination. Such a two- or more-celled body formed of spores- may
remain persistent on its sporophore, or may be separated from it in one of the ways
which have been described (see Fig. 34), or may be set free from a receptacle, while its
members remain firmly attached to one another; and this is the case in the great
majority of instances, and those the most typical. In these respects, therefore, its
behaviour is the same as that of many simple spore-cells, which it resembles also in
shape and size. Moreover it happens very frequently indeed in closely related species,
and sometimes even in the same individual, that cells of exact morphological
equivalence remain at one time undivided and form a simple spore, at another time
become by division pluricellular compound spores. The teleutospores of Uromyces
and Puccinia, the gonidia of Gonatobotrys which are one-celled bodies, and of
Arthrobotrys which are two-celled (Fig. 21), are among the many examples of
this kind, and especially in countless Ascomycetes with typical 8-spored asci the
spore-primordia develope at one time into eight simple spores (Figs. 39, 43,
45), at another into pluricellular bodies, which escape in this form from the asci
(Figs. 46, 47).

These facts have given rise to the phraseology which speaks on the one hand of
simple unicellular spores, and on the other of septate or pluricellular spores (multilo-
culares, cellulosae of Corda, semen multiplex of Tulasne). If the expression spore is
not to have a different meaning in different cases, but the same meaning in all cases,
and this is what ought to be, it is obvious that it can only be applied to the single
cell capable of germination; such expressions as pluricellular spores are therefore
sheer nonsense, yet to get rid of them entirely would require the establishment of a
perfectly new terminology, and to attempt this would be for many reasons a hopeless
task. The evil may be to some extent lessened by the use of the expression compound
spore and its correlative terms. The number of members (merispores) in a compound
spore is different in different cases, two in Puccinia, Arthrobotrys, and Anaptychia
ciliaris, three in Triphragmium, four in Phragmidium, Pleospora, and Sphaeria Scirpi,
&c., and they are arranged in one row or in more.

I have several times called attention in other places? to the subject of terminology
which has just been mentioned, and, as might be expected, without result owing to the
overpowering influence of habit and want of thought in descriptive terminology. The
whole matter may be made perfectly clear in form and expression if we start from

the conception of a spore which is always presupposed in this work, and say that
spores are produced from their primordia (primordial cells or initial cells) and these

1 Brandpilze (1853) ; Flora, 1862, p. 63. See also my ist ed., p. 123.

CHAPTER III.—SPORES OF FUNGI. 99

again from their mother-cells, such as asci and the like. Initial cells of the same
morphological value may in case A become spores directly, in case B may become by
division aggregates of spores, which were named above compound spores, but which
it would be better perhaps to designate by- the term previously suggested of sfore-
groups or sporiderms. The descriptions would thus be rendered short and clear, and
would stand the scrutiny of the attentive and thoughtful student. The result would justify
the experiment.

That compound spores are produced by ordinary bipartition with septation of their
initial cells, as represented in Fig. 49, has been recently confirmed by Strasburger'. I do
not here go further into the subject of Körber’s sporoblasts and the correlative terms”.
The long filiform initial cells of species of Cordyceps® divide into a very large number
of short cylindrical simple spores, but it is still a question whether the division is
simultaneous or by successive bipartitions. In these Fungi moreover the compound

FIG. 49. Sphaeria Scirpi, DC. a—« jive stages of devel of the spores in the order of the letters;
all drawn from specimens inside recently isolated and uninjured asci. /ripe ip d spores disch from the
ascus, After Pringsheim. a—e magn. 390, / 350 times.

spores, eight of which are formed in each ascus, break up of their own accord when
they escape into their numerous component parts, each of which can germinate by itself;
thus they are disuniting spore-groups, and their disunion may take place inside the
ascus. .We should be obliged to say in this case, according to the usual terminology,
that each spore breaks up into many spores capable of germination. In nearly related
genera, such as Claviceps, the filiform spores remain undivided till after germination,
and put out germ-tubes. The spores also of Cenangium fuliginosum, Fr. behave in
the same way as those of Cordyceps, while the spores of other species of Cenangium
do not disunite*. De Notaris® gives an account of the disunion of the spores of
Sporormia fimetaria, Not.

II. STRUCTURE OF THE RIPE SPORES.

Section XXX. In considering the structure of the ripe spore we must
distinguish between moszonless spores and those endowed with power of motion or
swarm-spores.

The motionless spores are much the most common, and everything that was
said in previous sections, with the exception of sections XVIII. aand XX. a, about the
development and discharge of spores, referred only to them. In the mature state they
are cells of extreme variety of form in the different species, most frequently round
or longer than broad, in Claviceps and some others elongated cylindrical tubes.

1 Zellbild. u. Zelltheil. ed. 3, p. 51.

2 Syst. Lichen. German. Einleitung.

® Tulasne, Carpol. III; Bot. Ztg. 1867, 1.

* See Tulasne in Ann. d. sc. nat. XX, ser. 3, p. 135.
5 Microm. Ital. Dec. V in Mem.R. Acad. d. Torino.

H 2

100 DIVISION I.—GENERAL MORPHOLOGY,

When ripe, and usually some time before they are ripe, they have a firm cell-
membrane which may in very many cases be divided into two layers, an outer layer,
the epzsporium or exosporium, and an inner, the endosporium, each of which may be
itself stratified. In delicate or small spores the separation into two layers is very
difficult to recognise, or cannot be recognised, before germination, and in some cases
it never becomes apparent (Exoascus) ; in the latter case the cell-wall, often wrongly
termed episporium, is a simple colourless or a coloured membrane.

In the numerous cases in which the two layers are to be distinctly seen, the
outer one is usually a firm membrane, of various colours and various shades of colour,
rarely quite colourless, and usually gives its colour to the whole spore. The surface
is either quite smooth, as in most of the teleutospores of Puccinia and in many
Pezizeae, or is more commonly furnished with thickenings projecting outwardly in the
shape of warts, spikes, wrinkles, or a net-work of ridges, which vary in thickness and
height in the different species, from the very delicate punctiform elevations of the
gonidia of Puccinia coronata, Eurotium, &c. and reticulations of Peziza aurantia and
Puccinia reticulata to the extremely thick warts of Genea, the spikes of Tuber
melanosporum, Octaviania and Triphragmium echinatum, and the anastomosing ridges
of Tuber aestivum. The outer layer isin these cases either homogeneous or stratified.
In acrogenously formed spores a thin outermost lamella is often distinguishable from
the rest, and is shown by the history of development to be the original delicate
membrane of the spore-primordium, which developed with the spore, while the other
lamellae are formed on its inner surface. The prominences on the surface of the spore
often belong, as in uredospores and Corticium amorphum, exclusively to this outer
envelope, which may be called the pr7mary lamella. The compound or septate spores
also are generally enclosed in the wall of the mother-cell, which developes with them
as a close-fitting sac (Fig. 51 /). The episporium of some spores shows a differ-
entiation perpendicular to the surface into portions of unequal density, a striation
or areolation, along with or instead of the stratification. Fischer von Waldheim? has
observed this in the Ustilagineae. The episporium of the aecidia of Phelonites
strobilina, Peridermium Pini, Caeoma pinitorquum, Chrysomyxa and other Uredi-
neae is particularly beautiful, appearing as if composed of small prismatic rods of
denser substance perpendicular to the surface of the spore and connected together by
narrower bands of a less dense and more transparent substance (Fig. 50). The
convex extremities of the rods project outwards like warts. The structure is best
seen when the episporium is made to swell by the application of sulphuric acid?.

The endosporium is usually colourless or at least much paler than the coloured
episporium, and is smooth and homogeneous or stratified ; it is generally distinguished
from the episporium by greater softness and delicacy, but by no means always by
less thickness.

Some spores have a number of pores or pits disposed in regular order on their
surface ; the number of these is usually definite, but: may vary within narrow limits in
the same species. Many of these pores serve as places of exit for the tubular outgrowths
from the spore at the time of germination, and may therefore be termed germ-fores ;

1 See sections LVI and LVII, and the literature cited there.
? See Reess, Die Rostpilzformen d. Coniferen ; also Bot. Ztg. 1879, p. 803.

CHAPTER III. —SPORES OF FUNGI. ol

others perform no such function and are therefore only simple pores or pits. The
position of the pores on the membrane is different in different species. The spores,
for instance, of Sordaria fimiseda, de Not. have at their apex a germ-pore which is
closed only by the outermost lamella of the membrane (Fig. 52). The germ-pores
of the uredospores which I have examined, those of Puccinia for example and
Uromyces, are sharply defined round holes in the endosporium, and are closed by
the episporium on the outside ; those of the teleutospores of the same genera appear
to be pits in the episporium, which do not however extend into its outermost lamellae
and seem to be closed on the inner side by the unpierced endosporium. Some, perhaps
many, uredospores (those of Puccinia graminis for instance) show a pit at their point
of attachment which is of no service for germination (Fig. 51). The spores of some
Basidiomycetes, as Hymenogaster Klotzschii, are furnished with a pit at the same

FIG. 50. Chrysomyxa Rhododendri. FIG. 51. Puccinia graminis. Small portion
Basidium from an aecidium bearing a of a hymenium; z uredospores with four germ-
chain of spores. For the explanation see pores in their aequator, ? a pair of teleuto-
the accompanying text and on page 7r. spores, the upper one with a germ-pore in
Magn. 600 times. its apex. Magn. 390 times,

place which seems to belong to the episporium. The majority of the spores of the
Basidiomycetes have no pit at this spot, but are prolonged into a small stalk which
Corda? mistook for a pit. This stalk, as far as I could ascertain in the large-spored
Corticium amorphum (see Fig. 30), is mainly a continuation or protuberance of the
endosporium, over which the episporium is not continued or is present only as a very
thin membrane ; the stalk itself shows a narrow lumen, or its membrane is thickened
to such an extent that the cavity has disappeared. There is no germ-pore in any of
these spores at the point of insertion. The spore of Coprinus has one germ-pore,
according to Brefeld, in the apex.

1 Anleitg. p. XXXII. ? Schimmelpilze, III.

IO2 DIVISION 1.—GENERAL MORPHOLOGY.

The episporium of some Ustilagineae, especially Ustilago receptaculorum, shows
also a broad pellucid mark covering 4 or 4 of the circumference of the spore, and
corresponding to a thinner spot which passes gradually into the thicker and darker
coloured wall around it.

Lastly, we may mention the delicate striae on the ovoid spores of Ascobolus
furfuraceus and its allies. These, according to Janczewski, are thin places in the form
of longitudinal slits which do not penetrate through the whole of the substance of the
violet-coloured episporium, and often form acute-angled anastomoses. The colour-
less endosporium is smooth, homogeneous, and with its surface unbroken‘.

The various lamellae and strata of the spore-membrane, of which we have
hitherto been speaking, are developed, as far as our present observations go, in the
same mode and succession as those of vegetable cell-membranes generally ; there is no
reason therefore for entering further in this place into the details of their develop-
ment than has been done in previous sections.

Besides the membranes, which have now been described, the spores of
many Fungi have on their surface envelopes or appendages formed of a colour-
less transparent gelatinous substance, which swells greatly and usually dissolves and
disappears under the influence of water, and shrivels up when treated with reagents
which withdraw water. They may be termed gelatinous envelopes or gelatinous
appendages. ‘They are found alike in spores formed in asci and in acrogenous spores,
in simple and in compound spores.

The ascospores of many of the Sphaeriaceae, as Massaria?, some species of
Sphaeria*, Xylaria pedunculata first mentioned by Berkeley‘, and Fuckel’s Hypo-
copreae and Coprolepeae, are surrounded with a gelatinous coating of varying depth
and with very faint circumscription. A similar structure is found in Rhytisma Androm-
edae, Hysterium nervisequum, and other Hysterineae. The compound spore of
Sphaeria Scirpi is enclosed in a delicate transparent sac, which fits close to its sides
but is prolonged at either end into a long conical appendage” (Figs. 46, 49).
The spores of many other Sphaerieae, species for example of Valsa and Melanconis ®,
have a subulate appendage or a semicircular knob at their extremities. A semilen-
ticular gelatinous appendage is found on the episporium on one side of the
round spores of Peziza melaena and the ovoid spores of Ascobolus furfuraceus,
P. and several of its nearest relatives’, which swells into a hemispherical or spherical
shape when the spores are discharged in water; Peziza convexula and Ascobolus
immersus, P.° have the entire episporium encircled by a broad gelatinous coat. The
common envelope, which encloses as in a sac the 8 or 16 spores in the ascus of the
forms of Ascoboli distinguished as Saccoboli, must also be mentioned in this place.

Among acrogenously produced spores those of the plant known as Myxocyclus

? See Boudier, I. c. on page 92.—Janczewski in Bot. Ztg. 1871, p. 768.

* Fresenius, Beitr., and Tulasne, Carpol.

> Sollmann in Bot. Ztg. 1862, 1863.

* Mag. of Zool. and Bot. II, p. 224 (1838); see also Tulasne, Carpol. II.
5 Pringsheim’s Jahrb. I. t. 24.

° Tulasne, Carp. II.—Fresenius, Beitr. t. VII, 22, 21.

7 Boudier in Ann. d. sc. nat. ser. 5, X.

® Coemans, ]. cu. on page 92.

CHAPTER III.—SPORES OF FUNGI. 103

confluens, Reess', have a broad gelatinous envelope round their large compound
spore-mass. The spore-heads in Acrostalagmus andthe heads of Myriocephalum
botryosporum composed of crowded branching spore-chains are enclosed in a
gelatinous envelope, and many other instances of the kind might be mentioned. To
this place also belongs the apparently homogeneous often very soluble gelatinous
substance which covers the gonidial layers in a great number of Ascomycetes, and
in which their spores are imbedded. See above on page 7o.

The morphological significance of the different appendages has still to be deter-
mined more exactly by the history of development. The gelatinous coatings and
large gelatinous envelopes of entire hymenia must in the case of acrogenously produced
spores be the gelatinous outer membranes of spores or spore-mother-cells, or the product
of their coalescence. In the case of many spores produced in asci it is 2 przor7 probable
that the appendages and gelatinous envelopes are also partial thickenings of the
outermost lamellae of the membranes, or are due to the gelatinous character of the
whole of the outer layer. This would be in accordance with Sollman’s statements #,
but the confusion that reigns in them with regard to the most elementary principles of
histology makes it impossible to trust them. The sac which encloses the spores of
Sphaeria Scirpi is certainly the primary outermost lamella of the membrane which at
first fits everywhere closely to the spore, and becomes expanded into the conical
appendages at the extremities of the spore as it ripens. Zopf* maintains that such
gelatinous appendages, especially in the Sordarieae, are portions of protoplasm
which have not been used in the formation of spores, that is, speaking plainly, are the
direct product of the protoplasm in the ascus which was not devoted to the spore-
primordia. This view is not altogether new, for Kützing * before ascribed a similar
origin to the entire episporium of Tuber; but it deserves consideration both as regards
the gelatinous appendages and as regards the episporium as a whole, especially
considering the analogy of the development of the oospores of Peronospora (Chapter
V); it has not, however, been distinctly proved.

Appendages of a different origin from these gelatinous ones are peculiar to the
ascospores of Sordaria fimiseda, S. coprophila, and others, and may even occur along
with them’. The spores of the first of these two species are in their early stages small
delicate ovoid cells prolonged below into a cylindrical stalk and rich in protoplasm. As
all its parts increase steadily in size, soft gelatinous thickening of its membrane with fine
longitudinal striation makes its appearance at both extremities of the spore, projecting
outwards in the form of a sharply conical usually hooked process, and growing in size
as the spore grows. When the spore has attained its full development the greater
part of the protoplasm moves from its lower cylindrical into the upper ovoid portion,
which is then divided off from the former by a transverse wall, while its membrane
becomes thickened and stratified, and gradually acquires a dark violet colour; the
cylindrical portion continues attached as a hyaline stalk to the dark spore (Fig. 52).
As appendages of this kind arising from sterile sister or neighbour cells may be

1 See Tulasne, Carp.—Fresenius, Beitr.

2 Bot. Ztg. 1862 and 1863.

3 Sitzungsber. d. Naturf. Freunde, Berlin, Feb. 17, 1880.

4 Philosoph. Bot. p. 236.

5 Woronin, Beitr. III.—Winter, Die deutschen Sordarien, Halle, 1873.

104 DIVISION I.—GENERAL MORPHOLOGY,

mentioned also the envelope-cells on the spore-clusters of Urocystis, which will be
described in Chapter V, but not the germ-tubes which appear inside the ascus
in Sphaeria praecox, and which were described by Tulasne ! as filiform appendages.
We have already spoken, in concurrence with Zopf’s views, of the physiological
import of the gelatinous appendages as organs which may serve to attach the asco-
spores to one another and to the apex of the expanding ascus. This is evident
in the case of the Sordarieae, in which the spores, each with its dark episporium, lie in
a row in the ascus one behind the other and in contact with one another, and the
conical gelatinous processes on each spore are firmly attached to those of its next

FIG. 52. Sordaria. ‘seda, de Not. D of the spores, the successive stages in the order of the letters. a—y
from recently isolated uninjured asci; /a fully developed spore but with the yellowish brown membrane still transparent and
the germ-pore visibleabove. ga ripe spore escaped from the ascus, with its membrane of a violet black colour. Magn. 390
times,

neighbour or are twisted round them. How far the function of these appendages is
the same in other cases is a question which requires further careful investigation.

Of the chemical nature of the spore-membrane only some isolated facts are known,
and the subject is still in need of more thorough examination. Hoffmann” has
collected together a variety of details on this subject.

Most spore-membranes, according to the concurrent testimony of all observers,
are distinguished by their great power of resisting decomposition and the influence of
strong reagents, more especially concentrated mineral acids. Many are only slightly

1 Carp. I p. 80.
2 Pringsheim’s Jahrb. II, p. 308.

CHAPTER IIL.—SPORES OF FUNGI. 105

affected even by concentrated sulphuric acid, the less so as a rule in proportion to the
depth of their colour, and, as might therefore be expected, the episporium usually less
than the endosporium. Others swell more or less strongly in sulphuric acid or
wholly disappear. In very many cases the application of concentrated sulphuric
acid is an excellent method of showing the minuter structural characters of the
episporium, partly because it is rendered more transparent, partly because the other
parts are destroyed or stand out from the episporium, which either bursts of itself or
is readily made to burst.

Coloured episporia are usually more or less destroyed by boiling in potash; the
reticulately thickened episporium of Tuber aestivum is entirely destroyed by this
means according to Schacht’, as is also the finely warted outermost lamella of the
spores of many Uredineae?. These membranes therefore resemble to some extent the
cuticle of the higher plants in their behaviour with reagents; but it has still to
be determined whether they agree with it in other respects also, and are therefore
of the nature of cork.

With a few exceptions, to be mentioned presently, spore-membranes are coloured
yellow with iodine and sulphuric acid after maceration with potash or Schulze’s
solution, or, if not, are not coloured blue, resembling in this respect the majority of
fungal hyphae.

These remarks apply to the single, simple spore in the strict use of the term,
and to the compound spore also.

The gelatinous envelopes and appendages and the other gelatinous lamellae of
which we were just speaking are affected by reagents in the same way as similar
bodies in other organs and classes of plants. They are as a rule very perishable and
soon disappear if the spores are sown in or on water.

The coloured episporium of the Ascoboli carefully studied by Boudier and
Janczewski (1. c. on page 102) has peculiar characteristics which we must not attempt
to describe in this place.

The entire membrane of the acrogenously produced spores of Peronospora
behaves in exactly the same way as the cellulose of the higher plants towards iodine
and sulphuric acid. Dilute solution of iodine is the only reagent which colours the
whole of the spore-wall of Currey’s Amylocarpus and the gelatinous envelopes of the
spores of Xylaria pedunculata * an intense blue. The outermost lamella of the episporium
of the spores of Corticium amorphum, Fr. (Fig. 30) with slender spike-like warts
is coloured a beautiful bright blue with watery solution of iodine, and dark blue
with iodine and sulphuric acid; the spike-like processes share in the coloration,
but the inner thicker lamella of the episporium and the endosporium remain
uncoloured.

The protoplasm of the spores of the Fungi is either dense and apparently
homogeneous, or it has a greater or less number of granules or drops of oil dis-
seminated through it, and in most cases appears to be colourless when a
single spore is examined under the microscope: in a few cases only it is coloured
by embedded pigments.

1 Anat. u. Phys. II, 193. ? De Bary, Brandpilze.
® Tulasne, Carp. I, II.

106 DIVISION I,—GENERAL MORPHOLOGY,

The fatty matter which it often contains appears in many cases in the form of
spherical drops; such a drop, often surrounded by smaller ones, occupies the
centre of the spore in Peziza Acetabulum, Helvella elastica, and other species. In
many other cases smaller drops «f oil are distribued without arrangement in
the protoplasm, or are collected at fixed spots in tolerably constant numbers. The
best known and most remarkable examples of this kind are found in the ellipsoid
spores of Peziza vesiculosa, P. Sclerotiorum, Helvella esculenta (Fig. 58) and their
allies, which have one or more rarely two drops of oil in their foci. In P. tuberosa and
P. hemisphaerica on applying iodine I saw spherical or irregularly shaped bodies which
were not previously visible make their appearance at those points, and acquire the
reddish brown colour of glycogen while the rest of the cell-contents became yellow.

A large proportion of the smaller granules, which are present often in consider-
able quantities in the protoplasm, may also consist of emulsionised fatty matter '.
The reddish yellow pigment of the spores of the Uredineae and of Pilobolus may also
be mentioned again in this place in connection with the fatty substances. See above,
page 7.

If a nucleus is distinguishable in the young spores it can often be still seen in the
same spores when they have reached maturity; but this is not always the case
even where the protoplasm is not clouded by granules or large drops of oil.

It has already been said that a round pellucid body is to be seen in the centre of
the protoplasm of some acrogenously produced spores, among the Hymenomycetes,
for instance, and in the teleutospores of the Uredineae, the real nature of which
is still undetermined, it being uncertain whether it is to be regarded as a nucleus
or as a vacuole. _

The ‘nuclei’ of older authors (before the year 1863) were for the most part
drops of oil, the real nature of which can easily be determined by reagents. Corda
and Tulasne, on the other hand, call the entire protoplasm of the spore the nucleus,
which may be quite right in itself, but which is not compatible with the cell-
terminology here set forth.

The protoplasm of the spore in the young state is rich in water, and when dry
absorbs water rapidly from its environment. A spore lying in water appears under
the microscope to be filled with it to turgescence. As it loses water it contracts, and
if the wall is thin the membrane either sinks in irregularly or forms definite folds ;
round or ovoid spores take therefore the shape of a concavo-convex lens, the edges of
which are often bent over towards each other, and the spore has thus the form of a
boat. Thick-walled spores do not change their form in drying, or change it but little.
In many cases an air-bubble is formed inside the protoplasm as it parts with water,
as in Peziza abietina and P. melaena, in species of Sordaria, in Melanospora parasitica,
&c.; so also in the gonidia of Cystopus (Hoffmann) and in the resting spores of Proto-
myces macrosporus. This is due to the fact that air, that is to say, some gas, is dissolved
in the contents of the fresh turgescent spore, and is set free as soon as the quantity of
water is brought down to a certain limit. The same result is produced if the spore
in the water is exposed to the influence of reagents like alcohol, glycerine, or sulphuric
acid which have the power of extracting fluids; the air-bubble disappears when
water replaces these reagents.

? Hoffmann in Pringsheim’s Jahrb. II, p. 308.

CHAPTER III.—SPORES OF FUNGI. 107

The spores of many Phycomycetes have the characteristics of autonomous moti:e
cells and are therefore named swarm-spores, or zoospores, as having motion like anima s.
They are always formed endogenously by simultaneous division (section XVIII), and
are liberated from the sporangium by the process of swelling described in section XX.
Their origin and their development, at least up to the period of germination, take
place only under water ; the species which produce them are inhabitants of the water,
or at least their sporangia find their way into water for the purpose of forming the
spores. The swarm-spores of the Fungi are usually roundish or ovoid protoplasmic
bodies without a firm cellulose-membrane. They generally contain one or more
vacuoles arranged in a definite manner which varies according to the species; a
nucleus has been found in recent times wherever it has been searched for and tHe size
of the subjects permitted. A flagellum or one or two slender cilia with the power of
lively motion spring from a definite spot in their surface as processes of the peripheral
layer of protoplasm, and by their means the spore shows a movement of rotation in
the water round its own axis and usually also a rapid movement of translation in
space in all directions. A third movement of undulation and amoeboid change of
shape alternates with the other two in most Chytridieae and in Monoblepharis. The
mechanism of all these movements is not better known in the present instance than it
is in other swarm-cells; they commence in some species (Saprolegnia, Pythium, the
Chytridieae) inside the sporangium sh >: ly before the liberation of the spores, and the
cilia consequently are by that time. already formed; in other cases, as Achlya and
Cystopus, the cilia and the movements make their appearance after the spores have
entered the water. The motion under favourable circumstances only lasts a short time
in the swarm-spores of the Fungi, sometimes only one or a few minutes; the spores
then come to rest, the cilia are drawn in cr disappear, a delicate cellulose-membrane
is formed, and either germination ensues or other changes take place in special cases
which will be described further on. The direction of locomotion is not affected in
most of the cases of which we are now speaking by rays of light falling on the spores
on one side, but this is the case in certain Chytridieae ; the spores of Polyphagus and-
Chytridium vorax* are phototactic, and the fact is all the more interesting, because
these Fungi are parasitic on swarm-cells which are also phototactic and contain
chlorophyll, namely Euglena and Haematococcus, and owing to the peculiarity just
mentioned they are in a position to follow the movements of their hosts and to over-
take them.

It is not desirable to discuss the little known mechanism of the movement of
swarm-spores in this place, for that would necessarily involve the consideration of the
same phenomena in the Algae, where they are more open to observation.

The zoospores of Fungi (Fig. 53) are usually ovoid or roundish lenticular with a
thick blunt margin, often pointed at the extremity which is in front when the spore
is in motion, and with one surface convex and the other slightly concave, so that when
seen in profile they have the shape of a bean. A roundish pellucid spot, a vacuole
in the granular protoplasm immediately beneath the surface, lies in the median line
of the concave side a little nearer the anterior than the posterior extremity, and a

long cilium springs from its anterior as well as from its posterior margin the
anterior cilium being directed forwards when the zoospore is in motion, the

1 Nowakowski and Strasburger. See Strasburger, Wirkung d. Lichtes und d. Warme auf
Schwärmsporen, Jena, 1878.

108 DIVISION I.—GENERAL MORPHOLOGY,

posterior being directed backwards and dragged behind. In Phytophthora infestans,
according to older observations which perhaps need revision, both cilia spring from
a point on the posterior margin of the pellucid spot.

These ‘ beanshaped’ zoospores are peculiar to the Peronosporeae and Saprolegnieae.
Similar but not the same forms are found in certain Chytridieae (see section XLVI). In
the genera Achlya, Achlyogeton, and Aphanomyces the spores are discharged from
an orifice in the sporangium without cilia and autonomous movement, and collect
before the orifice in close lateral union with one another, forming the surface of a
hollow sphere and a small head. As they pass from the sporangium on to the
surface of the sphere, each of them becomes itself spherical and forms a thin
firm cellulose-membrane. After a rest of some hours the protoplasm escapes from
this cell-wall and then assumes the characters of the bean-shaped swarm-spore. It
is only after the escape of the protoplasm that the cilia slowly develope at the spots
which have been described, and as they develope the movement sets in, beginning
as a slight swaying miotion and passing by degrees into quicker rotation and finally
into rapid movement of translation. In the sporangia of most species of the genus
Dictyuchus, as described in section XVIII, the spores are separated by firmly united
cellulose-septa ; after some hours’ rest the protoplasm issues from the cellulose which

1%

FIG. 53. Phytophthora infestans, Mont. @ a sporangium lying FiG. 54. Cladochytrium Iridis. a resting-
in water after the division is complete. 4 escape of the 10 swarm- spore with a brown membrane seen from the broad
spores from the sporangium. c sporesin the motile state. @ spores side. 4 the same rotated through 90° in the centre is
at rest and beginning to germinate. Magn. 390 times. a large fatty spherical body. c—e successive stages

of, ination ofa single sp ; the brown outer

coat opens by a lid and the inner cell developes into

a tubular receptacle of swarm-spores. @ formation

of the spores completed. e escape of the spores.

fa single swarm-spore. a—e¢ magn. 375 times, / 600

times.
surrounds it and then becomes a swarm-spore as in Achlya. But the spores are not
discharged through a single orifice in the sporangium, but each pierces through the
nearest spot of the lateral wall of the sporangium, and even also through the empty
membranes of the adjacent sister-spores.

In the genus Saprolegnia a peculiar mode of proceeding is the rule. The spores
are discharged from the orifice of the sporangium as ovoid motile bodies with
the pointed extremity anterior in the swarming. This extremity is hyaline and
two cilia project from its extreme point. The broad posterior portion is formed
of granular protoplasm in which three small hyaline vacuoles lie immediately
beneath the surface at laterally equidistant spots in the same transverse section. The
spore comes to rest after a brief period of movement which does not last usually
longer than a few minutes, assumes a spherical form and becomes invested with a
thin cellulose-membrane ; but some time after, some hours or even days, it emerges
again from the state of rest, the protoplasm escapes as in Achlya out of the membrane
and is transformed into a bean-shaped swarm-spore. Individual exceptions to this
dimorphism of single spores occur in all species, in so far as a spore may omit the
second swarming-period and pass directly from the first state of rest to germination.

The majority of the Chytridieae have small round swarm-spores which are capable
of motion as they leave the sporangium (Fig. 54). Their protoplasm, which is

CHAPTER III.—SPORES OF FUNGI.— GERMINATION. 109

otherwise tolerably homogeneous and transparent, contains one, or in exceptional
cases two or more, round and comparatively large drops of oil which are colourless
or coloured in shades of yellow and red according to the species, and are excentrically
situated; a nucleus has been shown to be present in some cases’, and it is more than
probable that it is present in all. A single very long cilium arises from one point
of the surface., The sudden curvature of the cilium occasions a backward and
somewhat hopping movement of the spore often alternating with longer periods
of rest, especially towards the end of the stage of movement; this stage either passes
directly into that of rest or, as most frequently happens, into a stage exhibiting a
creeping amoeboid motion, in which the cilium disappears or is dragged behind.

According to Cornu the zoospores of Monoblepharis behave in a similar manner to
those of the Chytridieae. Further details and figures illustrative of these points will
be found below in the sections of Chapter V which deal with the Peronosporeae,
Saprolegnieae, and Chytridieae.

III. GERMINATION OF SPORES.

Section XXXI. Spores begin to germinate under certain necessary conditions,
which will be considered further on, one only being mentioned here in passing, viz. a
supply of water.

Since Prevost published his Mémoir on Caries and Ehrenberg his Epistola de
Mycetogenesi the germination of a great number of representatives of most of the
divisions of the Fungi has been observed and described. If the attempts made to
procure germination have not hitherto in certain cases been successful, this is partly
no doubt because special conditions are requisite for the purpose and these conditions
have not yet been ascertained; with the study and determination of these the number
of failures is constantly diminishing. On the other hand, beside the spores which
have the power of germination, there are other cells in many species which resemble
the spores in origin and structure, but which so persistently withstand all attempts to
make them germinate that they must be considered to be incapable of germination.
These organs are only mentioned here in passing; their further significance will be
specially noticed below in section LXX.

The morphological process in germination consists generally in the fact that
phenomena of development are exhibited in the spore, which are specifically distinct
from those which lead to maturity.

These phenomena may vary, either in different kinds of spores, or in the same
spore according to the external conditions; for instance the recently matured
acrogenously formed spore (gonidium) of Phytophthora becomes the mother-cell
of swarm-spores in pure water containing much free oxygen; on the contrary in
nutrient solutions it usually puts out germ-tubes.

The changes in form which take place in germination group themselves naturally
under two heads. First, the germinating spore becomes the mother-cell of new
spores with or without important change of form, as in Protomyces, Phytophthora,
and Cladochytrium (Figs. 41, 42, 54). We may in this case speak according to
circumstances of spore-like spore-mother-cells or sporangia, instead of spores. This
would depend on the object and requirements of each occasion, without prejudice to

' Strasburger, l. v. page 107.

110 DIVISION I.—GENERAL MORPHOLOGY.

the terminology here adopted. Secondly, the spore grows out into one or more
tubular processes with the characteristics of hyphae, more rarely with those of the
Sprouting Fungi. The two kinds aie naturally connected together by intermediate
forms, and an instance of this has been already in effect given in Fig. 54. Other
instances and some partial exceptions in the simplest of the Chytridieae will be
described in different places in Chapter V.

The modes of formation of sporangia in germination have been already
considered in the foregoing sections; here, therefore, we have only the other

FIG. 55. Puccinia graminis. A pair of tel i li and sporidia 2. B
promycelium detached. C epidermis of the under surface of the leaf of ane vulgaris with a germinating
sporidium, the germ-tube of which has p d into an epid cell. D uredosp putting out a germ-tube

fourteen hours after being placed on the surface of ‘water ; four equatorial germ-pores are seen in the empty membrane
ofthe spore. C, D magn. 390 times, 4, B more highly magnified. From Sachs’ Lehrbuch.

mode to depict, which may be termed /ube-germination (Schlauchkeimung) and sprout-
germination (Sprosskeimung).

The characteristic feature in tube-germination is that the spore grows out
at one or more than one spot in its surface into a tubular process which is of the
nature of a fungal hypha. This the first product of germination is accordingly known
as the germ-/ube(Keimschlauch). If the tube receives sufficient nourishment it developes
directly in many cases into a mycelium or thallus like that of the parent, and it is there-
fore the primordium of the mycelium (Fig. 55 D). In other cases its normal development

CHAPTER III. —SPORES OF FUNGI.—GERMINATION. Ill

soon comes to an end; it elongates for a little while and then abjoints acrogenously
at the expense of its protoplasm a small number of spores unlike the mother-spore,
and itself soon dies away. The product of germination in this case bears the name
of promycehum which was given to it by Tulasne, and the abjointed spores are
termed sporidia (Fig. 55 A, B, Fig. 56). Both types of formation of germ-tubes are
always peculiar to certain species and to certain forms of spores, on which point
further remarks will be found in Chapter V; both behave alike in those first
stages of their development with which we are concerned in this place.

Taking the simple non-septate spore-cells first, we find the simplest formation
of the germ-tube among swarm-spores. As soon as they have come to rest and are
provided with a membrane, they grow out at one or two or even more points into a
cylindrical tubular process the membrane of which is the immediate continuation of
the membrane of the spore (Fig. 53.) In most of the non-motile spores the
proceeding is essentially the same, but with this difference, that the tube is covered
only by a delicate continuation of an innermost layer of the spore-membrane. It is
uncertain whether in the case of these spores the whole of the spore-membrane is
ever prolonged as the covering of the tube;
even where the spore-membrane before ger-
mination is delicate and without obvious separ-
ation into endosporium and episporium, the
delicate wall of the germ-tube may often be
clearly seen to be continuous with the layer of
the inner surface of the spore-membrane, as
in Acrostalagmus, Penicillium, &c. Even: where
an endosporium is stout its whole substance is
not extruded to form the membrane of the
germ tube, but only its innermost lamella, as in „porc Zerminating on the surface of water. The
uredospores. The advancing germ-tube breaks ne een
through the outer layers where the episporium, fine, ">"reelum sa sporidium Maem ap
is strongly developed, causing them to open by
valves or perforating them, and this either at spots not previously marked out by
any special structure, or in places where pits were formed before the spores had
matured and which were spoken of above as germ-pores. In a few cases the
development of the germ-tube and the swelling of the inner part of the spore
associated with it cause the layers of the episporium to break up into small pieces,
as in Ascobolus sp., Diplodia sp.*, and some others.

In some spores with a very stout episporium and a narrow germ-pore, as in
Coprinus, Sordaria, and Chaetomium, the tube as it passes through the pore is a very
slender protuberance, but immediately in front of the outer orifice of the pore it
swells into a round and comparatively broad vesicle and after that grows on as a
cylindrical tube, which may be branched or unbranched, a mode of growth which
looks peculiar and has given occasion to strange misconceptions”, but is really
nothing more than a special case not deserving any particular designation.

FIG. 56. Rhytisma Andromedae, Fr. Asco-

* Bauke, Beitr. z. K. d. Pycniden.
? Bot. Ztg. 1866, p. 158.

112 DIVISION I.—GENERAL MORPHOLOGY.

A more noteworthy special case which recalls the formation of swarm-spores is
that of the germination of the acrogenously formed spores (gonidia) of the plasmato-
parous Peronosporeae (Peronospora densa, Rab. and P. pygmaea, Unger) ; here when a
spore is placed in water the whole of the protoplasm suddenly swells and issues from
the papilla-like tip of the spore which opens to admit its passage, and assumes
the form of a spherical body, which invests itself at once with a new and delicate
cellulose-membrane and then puts out a simple germ-tube.

The number of the germ-tubes which proceed from a single spore is usually
small, 1,2, or 3, seldom only afew more. The germination of the spores of the genera
Pertusaria, Ochrolechia, Mass. and Megalospora, Mass., first observed by Tulasne? and
more closely examined by myself®, is therefore all the more striking. These spores which

Th N Wi7

FIG. 37. a—d. Megalospora afinis, Kbr. aa ripe ejected spore. dd ives tages of germination on a moist
microscopic slide; 4 and ¢ optical longitudinal sections only, ind the surface also is seen. e—/ Ochrolechra pallescens, Mass. ;
efirst beginning of germination in optical longitudinal section, /with el d germ-tubes. g Pertusaria deBaryana, Hepp. ;
optical longitudinal section through the half of a spore which is just beginning to i showing the canals with their

enlargements in the wall The specimen was treated with glycerine; the wall with its cavities appeared when fresh as in 5;
the contents of the spore are omitted. magn. 190, the other figures 390 times.

are formed in asci (Figs. 57, 59 A, 2) are unusually large (in some species 180 » and
more in length) and ovoid or ellipsoidal, filled with a dense oily protoplasm and sur-
rounded by a thick colourless stratified membrane usually of many layers. Each spore in
germination puts out simultaneously a large number, 50-100, of slender tubes, which
either spring from all parts of the surface of the spore, as in Pertusaria, or only from
the side which is towards the substratum. The tubes when formed have no special
peculiarities. The formation of a tube begins with the appearance of a narrow canal
running from the inner cavity of the spore in the outward direction, and passing at a
right angle through the inner layers of the membrane. The extremity of the canal
enlarges in the outer layers of the membrane and at their expense into a lenticular or
spherical cavity, in which a homogeneous protoplasm collects, and the cavity at once

* Mémoires sur les Lichens (Ann. d. sc. nat. ser. 3, XVII).
? Pringsheim’s Jahrb. V, p. 201.

CHAPTER IIIL-—SPORES OF FUNGI.—GERMINATION. 113

becomes invested with a very delicate membrane of its own and appears as a small
vesicle which elongates in the outward direction as the germ-tube and grows
through the episporium. In the thick-walled spores of Pertusaria the tubes often
ramify inside the episporium and the ramifications spread in it parallel with the surface
of the spore. The canals in the membrane are, as far as can be ascertained, new
formations at the time of germination, and are not enlargements of primordial forma-
tions. They continue usually so narrow that vesicles and germ-tubes appear at first
sight to be completely surrounded. On acccunt of the slight thickness of the epi-
sporium in Ochrolechia these project at an early period above the surface of the spore,
and, as Tulasne observes, may often be separated with the episporium from the
apparently uninjured endosporium. The use of reagents, especially Schulze’s solution,
shows the state of the case to be everywhere as it has been described, and this is
apparent in the large spores of Pertusaria even without their use (see the explanation
of Figs. 57 and 59 A, &).

In all cases the spore absorbs
water before the commencement of
germination, and as a consequence
of this it swells and forms vacuoles
(Fig. 58). If it contains a reserve
of food in the form of drops of oil,
these are seen to decompose and
disappear; the nucleus also becomes
indistinguishable. As soon as the
germ-tube begins to develope pro-
toplasm moves into it from the spore.
In many cases the germ-tube grows
exclusively at the expense vf tle TEs Bilplespnions Dea axbpsleemucmsrts
protoplasm and the reserve of food er The stages ofthe development follow the letters. Magn. 390
in the spore. Germination of this
kind takes place when water only is present, and succeeds best in water; examples
of it are to be seen especially in Fungi which lead a purely parasitic life, such as the
Peronosporeae and Uredineae (Fig. 55); the large spores of Pertusaria, Ochrolechia,
and Megalospora are also of this kind. In these cases the spores do not increase in
size after the first formation of germ-tubes; their protoplasm and reserve of food, with
the exception of an accidental and unimportant residue, passes over into the tubes in
proportion as they develope; water takes the place of these substances in the original
spore-cavity, and the spore-membranes thus emptied of their contents soon perish.

Other spores require a supply of nutrient substances as well as water in normal
germination, or at least absorb them when present. They then increase consider-
ably in size and their inner cavity is permanently lined with a layer of protoplasm,
like a vegetating cell; in other words they are permanently vegetating portions of the
mycelium that grows out of the spore, and it is not surprising that transverse
walls should also be sometimes formed in them. Many Mucorini, as Mucor
stolonifer and M. Mucedo, and the Sclerotinieae, as Sclerotinia Fuckeliana, are
excellent examples of this kind. Intermediate forms are found, as might be expected,
between the two extremes.

[4] ; I

114 DIVISION I.—GENERAL MORPHOLOGY.

In compound spores each merispore germinates in the same way as a simple
spore or has the power of doing so (see Fig. 59 C). It is not uncommon to see
a germ-tube proceeding from almost every merispore, even where they are many in
number, as in Pleospora herbarum and Cucurbitaria Laburni. Sometimes certain
merispores only germinate as a rule, and if the cells are arranged in a simple row
his is usually the case with one or both the terminal cells of the row, as in Melogramma

. Bulliardii, Tul., Melanconis,
Tul., Aglaospora profusa, Not.,
Exosporium Tiliae and the
stylospores of Cucurbitaria
macrospora. The merispores
which do not germinate gra-
dually give up their contents
to those which do}, that is,
their contents disappear and
are replaced by water in pro-
portion as the germ-shoots
develope. But theirmembranes
remain uninjured, suffering no
perceptible perforations.

The sprout germina-
tion occurs in single genera
and species, as Saccharomyces ?
Exoascus*, Dothidea Ribesia,
Fr.*, and some species of Nec-
tria®, not to speak of certain
doubtful forms like Dematium
pullulans which will be de-
scribed further on. Small pro-
cesses with a very narrow base
“sprout, likecommencing germ-
tubes, from the surface of the

germinating on a moist slide after long lying in glycerine. B Pertusaria ejopiaca, SPOTe, then generally assume
a ein boa ee um elongated or eylindrical

form, and finally are abjointed
in the manner described above in the case of the sprouting Fungi. A second
and third or more sprouts may follow the first from the same point in the spore,
till its protoplasm is exhausted. The sprouts may be formed at any point in the
spore (Exoascus, Dothidea) or at fixed points, as at the two extremities of the
fusiform dimerous compound spore of Nectria inaurata, or on the whole surface
of the spore which is thus thickly covered over with sprouts which stand out from

FIG. 59. A Pertusaria is. Optical longitudinal section of a spore

1 Tulasne, Carp. II, and I, p.95. See also Cornu in Comptes rend. 84 (1877), p. 132.
? Reess, Unters. ii. d. Alkoholgährungspilze, Leipzig, 1870.

3 De Bary, Beitr. I.—Tulasne in Ann. d. sc. nat. ser. 5, V. See also section LXXVII.
* Tulasne, Carp. II. t. IX. :

5 Janowitsch in Bot. Ztg. 1865.

CHAPTER III.—SPORES OF FUNGI.—GERMINATION. 115

it at right angles, as in Nectria Lamyi. In some of these forms, Saccharomyces,
Exoascus, Nectria Lamyi and its nearest allies, sprouting is the only known
mode of germination in the spores in which it is found; in others, as Dothidea
Ribesia, spores of a similar character exhibit some of them sprout-germination, while
others put out germ-tubes, which may or may not give off sprouts, and this is
the case also with the ascospores of Bulgaria inquinans, in which the germ-tubes
which give off sprouts swell into vesicles as they issue from the episporium (Fig. 60).
In the last-mentioned cases the proper growth of the tubes often ceases with the
‘formation of sprouts; they resemble therefore the forms described above as pro-
mycelia, and are connected with typical promycelia by a variety of intermediate forms
which will be dealt with in Chapter V.

Finally it must be remarked that the modes of germination here described take
place, as has been always hitherto assumed, after shedding and discharge of the ripe
spores; but a number of cases are known among the
Ascomycetes in which the spores germinate inside the 2 N
ascus which has just matured, and form simple germ- ¥ ie
tubes (Sphaeria praecox, Tul., Peziza tuberosa), or ©
form sprouts (Exoascus, Peziza Cylichnium, P. bolaris,
and especially Nectria). In some species this occurs
quite exceptionally, as in Peziza tuberosa; in others it
is very frequent, as in Sphaeria praecox, according to
Tulasne, in Exoascus and Taphrina; it may even be
the general rule, as in Nectria inaurata, Lamyi, and
others. As in the cases last described the products, ink rr ae Fr. Spores
of germination are numerous sprouts which are abscised 4,2 remyanın oe to be regarded
and from which in Exoascus new sprouts are at once
abscised, so in this case the ascus is often densely filled with the sprout-cells, so
that the original spores formed after the type of the Ascomycetes (section XIX)
are entirely concealed by them, a state of things which has given rise to all kinds
of misconceptions.

Historical review of spore-formation. Organs resembling the seeds of Phanero
gams and developing into new individuals were up to the times of Tournefort and
Micheli (1707, 1729) supposed notto exist in Fungi, or were at least but little sought
for, though it is true that a few places are to be found in older writers, which
speak of the seeds of Fungi. On this point Ehrenberg, Ep. de Mycetogenesi, and
Tulasne, Sel. Fung. Carpologia, Prolegomena, Cap. I, V, should especially be consulted.

The development of the spores was at first examined chiefly in the larger
mushrooms. Micheli, Nov. plant. genera (1729), saw the spores grouped in tetrads
on the lamellae of the Agarici (1. c. p. 133, tt. 73, 76), but did not perceive the
mode of their attachment; but he saw the asci of Tuber plainly and the spores in
the asci (l.c. p. 221, t. 102). Bulliard (Champ. de France, 1791) recognised the sterig-
mata (filets) on which the spores of the Hymenomycetes are placed, and O. F. Miiller
gave an excellent account of the spore-tetrads of Coprinus conatus in the Flora Danica,
Fasc. xiv. in 1780; Hedwig, Descript. &c. Musc. frond. (1788), discovered the eight-
spored asci of the Discomycetes, and he and the writers of the succeeding period
gradually found these organs in the majority of the orders of Ascomycetes; Persoon

1 Janowitsch, 1. c.
I 2

116 DIVISION I.—GENERAL MORPHOLOGY.

especially described them in 1794 in Peziza, Helvella, Morchella, Ascobolus, Sphaeria, and
Geoglossum in his epoch-making attempt at a classification of the mushrooms in
Römer’s Neues ‚Magazin f. Bot., I, p. 62. Persoon’s Icon. et descr. Fungorum, I
(1798), pp. 6, 25, should also be consulted; also J. Hedwig, Theor. generat. et fructif.
plant. Cryptog., Ed. 2 (1798), and from among later writers Ditmar in Sturm’s Deutschl.
Fl. III, 1, &c. Many of the accounts of these older authors are reproduced in
Nees v. Esenbeck’s System der Pilze und Schwämme, Würzburg, 1817.

The discovery of the asci in a large number of Fungi led first of all to the mistaken
assumption that all the higher mushrooms, and especially Hymenomycetes, are
furnished with similar organs. This view is expressed from the time of Persoon’s
attempt above mentioned, and especially of Link’s Observationes in Ord. plant. naturales,
1 (Magazin d. Ges. naturf. Freunde, Berlin, 1809), down to modern times (Fries, Syst.
Mycolog.; Epicrisis Syst. Mycolog.), and it is even represented, though somewhat ob-
scurely, in figures (Nees, Syst. d. P.). Further historical details will be found in the
writings of Berkeley, Phoebus, and Léveillé, which are cited below.

Vittadini, Monogr. Tuberacearum, discovered in 1831 or rediscovered the basidia of
Boletus and Hymenogaster, but it was not till after the appearance of the classical
and contemporary works of Léveillé, Recherches sur ’Hymenium des Champignons,
(Ann. d. sc. nat. ser. 2, VIII, 1837), and Berkeley, On the fructification of Hyme-
nomycetous Fungi (Ann. of Nat. Hist. I (1838), p. 80), that they became more
generally known and more carefully studied, especially in the Hymenomycetes.
Others obtained independent results which agreed with those of Léveillé and Berkeley,
but were not published for some time after; as—

ASCHERSON, in Wiegmann’s Archiv, 1838, and Froriep’s Notizen, Band 50.

PHOEBUS, Ueber d. Keimkérnerapparat. d. Agaricinen u. Helvellaceen (Nov. Act.

Acad. Nat. Curios. XIX, II), (1842).
CorDA, Icon. Fung. III, p. 40 (1839), in which Corda’s earlier observations are
noticed.
Berkeley and Tulasne were the first who supplied more exact information with respect
to the basidia of the Gastromycetes (see end of section XCIV), and Tulasne more
recently with respect to those of the Tremellineae in Ann. d. sc. nat. sér. 3, XIX.

Among later investigators of basidia J. Schmitz should be mentioned, Ueber The-
lephora hirsuta, &c. in Linnaea, Bd. 17 (1843).

The asci were simultaneously examined by Léveillé and Phoebus (l. c.), but without
adding anything very important to the results of previous observers.

In the more simple Fungi, the Hyphomycetes, Micheli (N. gen. t. 94) represents the
acrogenously formed spores of Botrytis and Aspergillus as placed on the extremities of
the hyphae. Succeeding writers for some time either gave similar accounts or were
unable to satisfy themselves with regard to the origin or insertion of the spores. Corda
in his later writings, Fresenius (Beitr.) and Bonorden (Allgemeine Mycologie) were
the first to throw mere light on the questions relating to the origin of the spores.
The reader is referred to their works and to the descriptive literature; no distinct
epoch marks the advance in our knowledge of these questions.

As regards more delicate questions of histology and development which have only
recently been brought within reach of examination, I was myself the first to make
more exact researches into the development of spores in asci in my work Ueber
die Fruchtentwickelung der Ascomyceten, Leipzig, 1863, after various previous writers
had prepared the way for more precise enquiries, such were—

NÄGELI in Linnaea XVI, p. 257 ;—Id. in Zeitschrift f. wiss. Bot. Heft. I, p. 45, Heft

III and IV, p. 23.

SCHLEIDEN, Grundziige, Aufl. 3, II, p. 45.

CORDA, Icon. fung. III, 38, V, 66, 74, 80.

FRESENIUS in Flora, 1847, p. 11.

CHAPTER III-—SPORES OF FUNGI.—GERMINATION. 117

SCHACHT, Pflanzenzelle, p. 50;—Id. Anat. u. Phys. d. Gew. I. pp. 71, 73, 170.

KUTzInG, Philosoph. Botanik, p. 236.

TULASNE, Fungi hypogaei ;—Id. Selecta fungor. Carpol I.

HOFMEISTER, in Pringsheim’s Jahrb. Bd. II, p. 378 (Tuber aestivum).

SOLLMAN’s Beitr. z. Kenntniss d. Sphaeriaceen (Bot. Ztg. 1862 and 1863) made no im-

portant additions to our knowledge for reasons which have been already given.

More recent works on the Ascomycetes have confirmed in all important points
the views published by me in 1863, while those of Strasburger and Schmitz quoted
in section XIX have supplied the corrections that were rendered necessary by the
modern doctrine of the cell. Boudiers account of Ascobolus has been confirmed

by Janczewski (Bot. Ztg. 1871) in those points in which it differs from that given by
myself.

The formation of the spores of the Mucorini has been described by—
CorDA, Icon. fung. II, p. 19.

FRESENIUS, Beitr. p. 6.

SCHACHT, Pflanzenzelle ;—Id. Anat. u. Phys. d. Gew. I.

HOFFMANN in Bot. Ztg. 1856 ;—Id. in Pringsh. Jahr. II.

Coun, Entw. des Pilobolus, N. Act. XIII.

COEMANS, Monogr. du genre Pilobolus, in Mém. pres. de l’acad. Brux. XXX.

DE Bary, Beitr. z. Morph. u. Phys. d. Pilze, p. 83, and in the literature cited in section
XVIII.

Corda, Fresenius, Schacht, and Hoffmann consider the formation of the spores in
the Mucorini as more or less closely allied to that which takes place in the asci,
as a process therefore of free cell-formation within the protoplasm of the mother-cell
and at the cost ofa portion of it, and this view has been quite recently maintained
by Brefeld (Schimmelpilze). In the same way the acrogenous abjunction of spores has
also been regarded by later writers as a process of free cell-formation, which differs from
that in the typical asci only in the circumstance that the daughter-cells arise in special
protuberances of the ascus. Vittadini (Monogr. Tuberac.) goes so far as to make the spore
of the Hymenomycetes and Gastromycetes arise inside the basidium and afterwards
emerge from it enclosed in a protuberance of the inner layer of the membrane, the
sterigma. Montagne takes a similar view in the Esquisse organographique. Schleiden
also, in his Grundzüge, Aufl. 3, II, p. 38, and Schacht (Pflanzenzelle, p. 54, and
Anat. u. Phys. d. Gew. I, p. 74) are of the same opinion, and H. Hoffmann in the Bot.
Ztg. 1856, p. 153 and in Pringsheim’s Jahrb. II, p. 303 adopts it in the most decided
manner ; he says, ‘ One fundamental type with many variations occurs again and again ;
the spores are formed by free cell-formation inside mother-cells (tubes), which some-
times becomes cemented with them, as in Phragmidium, Agaricus, and Phallus,
sometimes only loosely envelope the spore or spores, as in Mucor, Peziza, and Tuber.’
Van Tieghem and Le Monnier in the Ann. d. sc. nat. sér. 5, XVII, pp. 332 and 370, and
sér. 6, I, p. 37 have recently re-introduced this way of explaining the acrogenously
formed spores of Chaetocladium, Piptocephalis, and Syncephalis ; they represent them
as produced endogenously and singly or in a simple row in sporangia placed close to
one another, like the spores of Mucor or Mortierella, but they do not rest their view on
distinct facts in the history of development. These notions are not in harmony with
clearly ascertained facts, as Berkeley (Ann. and Magaz. of Nat. History, Vol. IX (1842),
pp- 9, 283 note) and Tulasne (Il. cc.) have always contended; they arose in the case of
Schleiden from his erroneous views on the first principles of cell-formation, views

-which have long been abandoned; in the other writers above mentioned evidently
from a striving after the establishment of homologies, for which purpose, however,
they would be superfluous if they were correct. The present state of our knowledge
of cell-formation and cell-division, as it is briefly stated on page 61 and fully explained

118 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

.

in the third edition of Strasburger’s Zell-bildung u. Zell-theilung, admits of our conceiving
of all spore-formation as special cases of the process of cell-division without doing
violence to the facts, and makes any further discussion of the points in controversy
unnecessary.

The historical data respecting the swarm-spores of the Fungi and their development
are to be found in the following works :—

PRINGSHEIM, Entw. d. Achlya prolifera, (N. Act. Acad. Nat. Cur. XXIII, p. 1);—Id.

Jahrb. f. wiss. Bot. I, 290; II, 205 ; IX, 191.
A. BRAUN, Verjüngung, p. 287, and Ueber Chytridium (Abh. d. Berlin. Acad. 1856).
DE Bary in Bot. Ztg. 1852, p. 473 ;—Id. in Pringsheim’s Jahrb. f. wiss. Bot. II, 169.
On the swarm-spores of Cystopus, Id. Ueber Schwärmsporenbildung b. Pilzen
(Ber. d. naturf. Ges. Freiburg, II, 314, and in Ann. d. sc. nat. ser. 4, XIII ;—Id.
Sur le développement de quelques Champ. paras. (Ann. d. sc. Nat. ser. 4, XX).

SCHENCK in Verhandl. d. phys. Ges. in Wiirzburg, IX.

B. PREVOST, Mém. sur la cause de la Carie ou Charbon des blés, Montauban, 1807.

LEITGEB in Pringsheim’s Jahrb. VII, 357.

CORNU, Monogr. d. Saprolegniées, Ann. d. sc. nat. sér. 5, XV.

Lastly, the formation and abjection of acrogenously produced spores and the develop-
ment of the spores of Saprolegnieae, Peronosporeae,and Mucor have been lately reviewed
in the works of A. Zalewski, Ueber Sporenabschniirung und Sporenabfallen bei den Pilzen,
Diss. and Flora, 1883, and by M. Biisgen, Die Entwickelung. d. Phycomycetenspo-
rangien, Diss. and in Pringsheim’s Jahrb. XIII, Heft 2 (1882).

The special works quoted in Chapter V should be referred to for details connected
with this subject.

DIVISION II.
COURSE OF DEVELOPMENT OF FUNGI.

CHAPTER IV. INTRODUCTION.

Section XXXII. There can be no question that the course of development of
Flowering plants, Pteridophytes, Mosses, and most of the better-known groups
of Algae is very nearly alike, in spite of all the multiplicity of detail and all the
variety exhibited by the extreme forms in these great groups of the vegetable
kingdom. In Ferns and Mosses where it is most absolutely differentiated two stages
alternate periodically in each species; one of these takes its origin from the spore
and ends with the formation of antheridia and archegonia, while the other is the
regular product of the oosphere of the archegonium and ends with the formation of
spore-tetrads. However much in the above-named classes the equivalent chief
stages, that which produces archegonia and that which produces spores, may differ
from one another in conformation, differentiation, and physiological character, it
is quite evident that they agree together in the chief points here briefly indicated
and in several matters of detail. Suppose the paths pursued by the development in
the species to be laid down as similar geometrical figures, then the several similar
members, the archegonia, spores, &c. will occupy corresponding sections in the
figures. Members and stages of the development in different species, which thus
correspond to one another, are said to be homologous. The view that homologous
members of different species are the result of modifications of a member of an
ancestral type is based on the theory of descent. The phylogenetic or ‘natural’
affinities of a species are proved by demonstrating the homologies.

It is an accepted truth, which therefore does not require a formal demonstration
in this place, that strict homologies may be shown to exist between Ferns and Mosses
on the one hand and Phanerogams on the other, and that these homologies imply
not only phylogenetic affinity, but also that agreement in the periodic succession of
the two main stages, or we may say in the general rhythm of the development in
the different species, to which attention has just been called. The same may be
said of relations of affinity between most groups of Algae and Mosses.. It
follows that all these portions of the vegetable kingdom are closely united by
bonds of relationship into one large main group with a like course of development,
in a word into one main series of the vegetable world which then divides, in
accordance with special phenomena, into a few subordinate series‘.

It was for a long time a reasonable matter of doubt and may to some extent be so
still, whether Fungi are naturally related to this main group, and at what point they

1 See Bot. Ztg. 1881, 1.

120 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

connect with it. The question was scarcely ripe for discussion at all before the
middle of the present century, for scarcely anything was known of the life-history of
the Fungi. Botanists were acquainted with single forms only, and it was known that
some of these were reproduced in a like form from spores, as a tree of a distinct species ,
is reproduced from its seeds; hence every distinct form which produced anything
that resembled spores was considered to be the complete representative of a species.
These form-species and the form-genera composed of them had for the most part only
a distant resemblance to non-fungal plants. In the comparative simplicity of their
structure they approached nearest to members of the lower groups of Algae, the
course of whose development was also then very imperfectly known; hence the
Fungi were always placed next the Algae, but no points of connection were
established to show a closer natural affinity between the two groups. But while
Hofmeister’s ‘ Vergleichende Untersuchungen’ were giving a new impulse to the com-
parative study of the Mosses and Ferns and of the Algae also, and supplying a number
of new points of view, the study of the Fungi was directed into new paths after the year
1851, especially by Tulasne!. Starting from a few observations by older writers which
had been repeatedly neglected Tulasne undertook to show that the form-species of myco-
logists up to that time did not in many cases represent a true species, but that such a
form-species might be part with others of the cycle of development of a true species.
He showed that a regular succession in time takes place in this development between
the forms which belong to the species, that, as we now say, the appearance of
the successive forms indicates the successive stages in the development of the species.
Beginning with the Ascomycetes he extended these views in many publications,
which will be cited below, over a large number of different groups of Fungi.

Tulasne rested his views chiefly, if not exclusively, on the proof of the
anatomical continuity of the forms which occur in the fully developed state, of
the origin, for example, of the sporophores in question from one and the same
mycelium. The sowing and culture of spores under careful management and
watching, which were introduced especially by myself, gave us a more accurate
acquaintance with the succession of forms. The application of these two methods
of investigation has at present resulted in showing* that a certain number of groups
of Fungi are associated by the rhythm of their development with the main series of
the vegetable kingdom indicated above, and approach nearest to the ovigerous Algae ;
the stages of their development are homologous with the stages of those Algae from
which the Fungi may be phylogenetically derived. To these forms I give the name of
Ascomycetous Series or Main Series of Fungi, composed of the Phycomycetes,
Ascomycetes, and Uredineae. Other groups of Fungi, especially the Ustilagineae and
the Basidiomycetes, cannot in the present state of our knowledge be ranked with
the Ascomycetous Series, though they connect with certain members of the series
as phylogenetically derivative through divergent lateral lines.

It follows from what has now been said, that to give an account of the course of
development of the Fungi we must submit the groups one by one to a comparative
examination. This account should begin with the Ascomycetous Series and include a

1 Comptes rend., 24 and 31 March 1851, and Ann. d. sc. nat. ser. 3, XV.
* See Beitr, z. Morphol. u. Physiol. d. Pilze, IV.

CHAPTER IV.—INTRODUCTION, 121

comparison with allied forms which are not Fungi. For the latter object it will be
well to recall briefly in the first instance the phenomena generally characteristic of
the course of development in those groups, which in a comparative account come next
to the Fungi, viz. the Algae, Mosses, and Ferns. It is presumed that the details,
for which the reader is referred to Sachs’ Text-book or Goebel’s Outlines of Classifi-
cation, are already known.

Section XXXIIL In all the above groups, with some exceptions, which,
however, are so extremely few that they may be at first disregarded, we may set out
from a cell which is fertilised by the sexual act of conjugation, or from a cell-group,
its equivalent, which has been shown to be everywhere homologous and may
therefore be designated by a common name. For this name we may choose the
word archicarpium (archicarp), meaning commencement of fructification, with refer-
ence to the evident fact that the body usually known as the fructification very often
proceeds from it as the immediate product of development. In the Ferns and
Mosses the archicarp is the oosphere in the archegonium ; in the two chief classes of
flowering plants it is the cells which are the homologues of the oosphere and in some
cases bear the same name; in the Florideae it is the procarpium (procarp), which
consists of a single cell or a small cell-group; in the ovigerous Algae, as Vaucheria,
Chara, Oedogonium, Coleochaete, it is also a single oosphere which in this case
is formed in the oogonium; lastly, in the isogamous Algae, as the Zygnemeae,
Desmidieae, and Botrydium, it is any gamete-cell which conjugates normally with a
similar cell.

If now we follow the course of development onwards from the archicarp,
fixing our atfention first of all on the simplest cases which are confined as it were to
the most necessary members produced by development, we find the archicarp
consisting of a single cell become under favourable conditions a spore, i.e. a cell
capable of growing directly into a vegetative body like the parent, and giving rise to
fresh archicarps as the last product of the development; with these archicarps the cycle
of development begins anew. This is the history of Vaucheria aversa', Chara, Fucus,
and Spirogyra. The case is one degree more complicated, when other conditions
being the same one spore is not formed directly from the archi¢arp, but a pluri-
cellular body unlike that which produced the archicarp, all or some of the cells of
which have the qualities of spores in the sense indicated above, and so far as this is
the case are capable of developing into other bodies bearing archicarps. Such a
body the product of an archicarp and essentially serving to the formation of spores
is termed a sporocarpium (sporocarp). ‘The Florideae and the Mosses afford excellent
and well-known examples of this kind. But we meet with a certain number of
cases of a much less marked character which form a very gradual passage to the
phenomena just mentioned as occurring in Vaucheria aversa and Fucus, for the ripe
oospheres of Coleochaete, Oedogonieae, Desmidieae, &c., which divide into many or
into four or only two daughter-cells developing into spores, are strictly speaking merely
sporocarps which have undergone successive stages of simplification in the order
here indicated. We may indeed say that if only two cells with the function of spores

1 Walz in Pringsheim’s Jahrb. V.

122 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

were formed by division from the spore which is the product of the archicarp of
Vaucheria, it would be a sporocarp though a sporocarp of very simple form.

By the term sporocarp we designate bodies originating in the manner just
described which serve almost exclusively to the formation of spores, and which cease
to exist after häving once with comparative rapidity developed a certain number of
spores. This is distinctly true of the majority of the illustrative cases adduced above
and of the simpler ones also. But here too a gradation of difference may be
observed, not only in the number of different successive steps in the development
which have to be traversed, but also in the number of repetitions of the same step.
Compare in respect to the first point the rapid and simple development of the
sporocarp of Riccia with the tedious and complicated development of Polytrichum
or even of one of the Jungermannieae ; in respect to the second point compare
Riccia with Anthoceros.

If while other conditions are again the same the differentiation of the sporo-
carp is carried beyond the conventionally and traditionally determined limit,
the formation of spores is confined to definite comparatively small segments or
portions of segments of the body developed from the archicarp; and if the
formation of these sporogenous segments is repeated in a periodical succession, which
is typically and in most cases also actually unlimited, we cease to use the term
sporocarp. We may adopt the word sporophyte or any other suitable and plain
expression in its place. This case occurs when we pass from the Mosses to the Ferns
and the classes of the Flowering plants arranged in series with them. Here again it
is presumed that the facts on which the term sporophyte is based are already known.
In the Ferns the leafy sporiferous plant is the sporophyte developed from the
archicarp which is the product of the prothallium; in the Phanerogams the
sporophyte is in like manner the entire growth from an oosphere (archicarp), with
the exception of the embryo-sacs, each of which is the homologue of a spore and of
the products of development other than the embryo which are formed in the sacs‘.

In flowering plants the sporophyte and the body from which it originates,
the oosphere, are so related to one another as regards their size and position that
the oosphere appears to be’a small portion of the sporophyte. The opposite is the case
in Vaucheria, Fucus, and Chara, where the sporophyte or sporocarp is reduced, so
to speak, to a single spore which forms a small portion of its parent. ‘In Ferns,
Mosses, Florideae, &c. the relationships of the two bodies are less unequal; both
alike appear as special stages of the development which proceed from one another in
turn, and it is for this reason that these plants have served as guides in the
determination of the morphology of the rest.

The course of development described above may follow the rule there laid down
without any further complication. Instances of this may be seen in Chara crinita, in
the apogamous Ferns” with some slight limitation which will be noticed hereafter at
greater length, and also in Coelebogyne®. But these are only isolated exceptions.
The almost universal rule, as is well known, is that the development of the

1 It hardly need be observed that it does not affect the questions with which we are at present
concemed, whether the strict homology is between fern-spore and embryo-sac or between mother-
cell of the fern-spore and embryo-sac.

2 See Bot. Ztg. 1878, p. 449. * Strasburger, Ueber Polyembonie, Jena, 1878.

CHAPTER IV.—INTRODUCTION. 123

archicarp into a spore, sporocarp, or sporophyte is not possible without a sexual
act of conjugation, and hereby, to speak generally and without regard to indi-
vidual details, a morphological ‘complication is introduced. The simplest case
of the kind, that of the most typical conjugation, may be described as the union of
two similar archicarps. In other cases male sexual organs are formed differing from.
the archicarps. The production of these organs is an essential distinction; they are
essential segments of the stage of the development in which the archicarp
is formed, and are absent from the other stage which is developed from the
archicarp. The two stages have therefore been naturally distinguished as
the sexual and the asexual; the distinction is quite correct since it corresponds
to that which is the almost universal rule, but it is to be observed that the
sexual function of the segment in question is of no moment in morphological
consideration and comparison; and the distinction by putting forward the sexual
function lays stress on that which is not generally essential, because, as we learn from
cases of parthenogenesis or apogamy, sexual processes may entirely fail, the
segments which have usually sexual functions being functionless or altogether
wanting, without causing any essential change in.the entire course of development.

It is indeed true that cases of parthenogenesis and apogamy do occur in which
the elimination of the sexual functions is accompanied by a change in the course of
the development; speaking figuratively, by a partial flaw or displacement in the curve
which represents it. This is not always the case, as for example in Chara crinita.
Instances of it occur in the apogamous Ferns, when the sporophyte, instead of being
developed out of the archicarp, shoots out from the prothallium beside it or without
its formation at all. It appears still more strikingly in the formation of adventitious
embryos observed by Strasburger in certain Phanerogams. Here the course of
development shows a distinct interruption of the strict homology with the nearest
allied species, though the homology is at once and completely restored as the de-
velopment proceeds. In such cases therefore we may speak of zwterrupted and restored
homologies.

A further complication of the course of development is introduced by the assign-
ment of the sexual functions and the corresponding morphological differences to
different individuals, each the product of a single spore ; by this means the differences
are carried in extreme cases as far back as to the parent-spore, or, as in the Phanero-
gams, to the sporogenous segments of the sporophyte. This brief notice of the above
well-known phenomena is all that is required in this place.

In the cases which we have been considering the ripe spore usually separates
from its connection with the parent-organism and developes under favourable
conditions into a morphologically and physiologically independent individual, to use
the customary phrase, or into a bion. The sum-total of the bions produced from one
parent-organism (and from its sisters) is termed a new or the next youngest generation.
Solution of continuity and development of the separate segments into a new
and independent generation may also occur at other places in the course of the
development than that of spore-formation ; the embryo of the Ferns and Phanerogams
which is developed out of the archicarp is an instance of the kind. If the solution
of continuity occurs several times and at dissimilar places in the course of the develop-
ment, as for example in the Ferns, the course of development is divided into unequal

124 DIVISION II.—-COURSE OF DEVELOPMENT OF FUNGI,

generations of independently living bions proceeding alternately from one another.
This phenomenon has been known since Steenstrup’s time as alfernation of generations’.
This takes place in-the Ferns between the sporophyte developed out of the
archegonium as the one generation, and the prothallium which grows from the spore
and bears archegonia as the other. The two chief stages in the course of the
development answer in this case to the two alternating generations, and hence
the term generation or alternating generation has been extended to the two relatively
homologous chief stages in the course of the development which were distinguished
above, and its rhythm as there described has been commonly termed the alternation
of generations, without regard to the biontic independence or continuity of the
successive stages. This is one meaning of the expression alternation of generations,
and it is the one strictly adhered to by Sachs especially (see his Text-book). By this
use of the expression the entire course of development is always composed of two
alternating generations, the sexual which closes with the production of sexual organs,
and the asexual which proceeds from the other and forms spores, or of the homologues
of these two generations.

Further complications may make their appearance in the course of the develop-
ment which we are describing and at very different places in it, inasmuch as portions
besides the archicarp and its products may separate as reproductive organs from
the body in one stage of the development, and grow into new independent bions
resembling their immediate parent. Each of these bions may then under favourable
conditions reproduce the other stage of the development, the other alternating
generation, and thus return into the typical path. Organs of reproduction of
this kind increase the number of single segments of a stage of the development; they
may be compared to branches and are in fact connected with them by many
intermediate forms, being generally distinguished from them only by the fact that they
separate from the parent-form, while what is termed a branch does not. They
usually serve in an especial manner for the multiplication and dissemination of the
bions belonging to the particular species, and are therefore fitly termed organs of
propagation. ‘They are always asexually produced and separate in very different states
of development from the parent-shoot; they may be highly differentiated shoots,
or small tubers composed of a few cells, or single cells—drood-buds, bulbils, brood-cells
(spores), &c. They are wanting in some species, as in Vaucheria aversa, V. dichotoma,
Preissia commutata, many Filices and Dentaria pinnata, while they occur abundantly
in their nearest allies, as for example in Vaucheria sessilis, V. sericea, Marchantia
polymorpha, Lunularia, some Filices and Dentaria bulbifera. In the latter case they
may not only become highly characteristic members of the species, but may actually
multiply the species through an unlimited number of generations and always in the
same form, and thus divert it from the typical rhythm of the development which
is preserved unaltered by the allied forms. External causes often cooperate
to a considerable extent in this process, and the possibility of a return to the typical
rhythm is still preserved as was stated above. It is easy to ascertain this rhythm in
the more highly differentiated forms, in the Phanerogams, Filices, Mosses, and some
Algae. To do so in the lower and comparatively simply organised plants requires

* Ueber d. Generationswechsel, Kopenhagen, 1842.

CHAPTER IV.—INTRODUCTION. 125

careful examination and a comparison of allied species. In dealing with such plants
the observer is confronted by difficulties arising from the strong preponderance of the
propagative forms, from the variety of shapes which they assume in the same species,—
a variety sometimes due to external causes, sometimes established by inheritance,—and
lastly from the alternation in some species, partly due to external causes, partly also
hereditary and constant, between purely propagative and fructificative generations of
bions returning again to the typical rhythm. Excellent examples are afforded by the
history of the development of Botrydium and Acetabularia!; many of the Oedogonieae
are connected with Botrydium as presenting a simpler case of what may be termed
facultative alternation of bions, while the gynandrosporous Oedogonieae in which this
alternation is a necessary part of their course of development connect with Acetabularia?.
In these instances we have succeeded in ascertaining the typical rhythm from the
successive production and reproduction of the forms. In many of the lower species
this has not yet been done, and there are still some comparatively highly differentiated
species in which the rhythm of the development is not yet fully made out; this is
especially the case with the numerous species of the Florideae, in which the
propagative organs (tetraspores) are assigned to special plants having no archicarps
or antheridia, We have not yet exactly ascertained the genetic relation or possible
relation of alternation between these forms and those first mentioned; but we know
that the organs of propagation do not occur on special plants in all the Florideae, and
that they are not generally necessary members of the course of development in these
plants, but are entirely wanting in some species.

Where fructificative and purely propagative generations of bions proceed
alternately from one another, it is also quite natural to speak of alternating generations
and of alternation of generations, using the latter expression therefore in a less limited
sense than Sachs. The practice is adopted in this work in accordance with the
original meaning of the word; alternation of generations here indicates every kind of
course of development, which is made up of alternating generations of independent
pions. In this very obvious sense the word is both necessary and convenient.
In every other sense it means nothing more than the rhythm of the development,
and the homologous alternating generations are merely homologous stages of the
development. To term these stages generations, even where they are not independent
bions, may be convenient for comparing them with homologous independent bions;
but if the practice is carried beyond certain narrow limits, into the succession of shoots
&c., every course of development necessarily becomes an alternation of generations,
and the expression ceasing to have a special signification becomes therefore
superfluous or objectionable.

It has already been pointed out that the main series of the vegetable kingdom
contains species, in which the propagative form of development greatly preponderates,
and is in fact the only one which does or can make its appearance through a long
succession of generations. In these species therefore a fructification is a comparatively
rare occurrence. But the existence of the species is not prejudiced by this
morphological defect, for so it may be termed ; and experience shows further that the
preponderance of the propagative form of development may be carried so far, that no

1 Bot. Ztg. 1877. ? See Pringsheim’s Jahrb f. wiss, Bot. I.

126 DIVISION II,—COURSE OF DEVELOPMENT OF FUNGI.

fructifications are ever formed. Clear instances of this are seen in Ulota phyllantha
and especially in Barbula papillosa among the Mosses, and in Allium sativum and
some other species among the Angiosperms!. In these cases also it cannot be shown
that the species has less than the usual power of maintaining its existence. The
names show that we are dealing with species whose nearest congeners go through the
complete normal course of development which includes the formation of fructifications,
and it may be proved, as has been done in another place, that in the former species
the fructificative members of the course of development have been excluded and have
disappeared in the progress of the phylogenetic evolution, and that the species
themselves therefore are in a reduced state owing to the loss of the most highly
differentiated stages of the development. Homologies with allied and perfectly
differentiated species may be followed for a certain distance, and then the homology
breaks off, is zuierrupfed and is not restored; the course of the development
as a whole has become different from that of the type.

This interruption of the homologies and the above-mentioned restitution of them
occur only in isolated species among the higher forms. If other species following the
same general plan of development were to be produced phylogenetically from them,
they would form secondary series in the vegetable kingdom which would diverge from
the main series and not fit into it. It is possible that such secondary series do exist
among the lower groups of plants which are not Fungi, but this is not yet certainly
ascertained. It was hinted above that we must assume the existence of such forms
among the Fungi, and proof of this necessity will be given in future sections,

The points of view explained in the foregoing paragraphs will enable us to under-
stand fully the phenomena known as the alternation of generations in the vegetable
kingdom. Other facts and other points of view may have to be considered in
reference to some of the similar phenomena which occur in the animal kingdom, but
we cannot discuss them here. Views differing from those here expressed, and as it

seems to me unnecessarily complicated, have been advanced on more than one
occasion. On this point the reader is referred to Pringsheim and other writers”.

Section XXXIV. The general phenomena to which attention has been called
in the preceding pages recur everywhere in the Fungi also, that is to say, the
phenomena observed in the Fungi are only special cases of phenomena which are of
general occurrence in the vegetable kingdom, and the Fungi from the purely
morphological point of view are ‘like any other plants.’ This has gradually come
to be understood since Tulasne’s work of reformation mentioned above. He himself
could not possibly have a clear view from the first of the meaning and application of
his discoveries in every direction. He therefore named the phenomenon which he
had discovered the pleomorphy or pleomorphism of the Fungi, especially of their
reproductive forms, and as these expressions clearly indicate the discovered facts and,
do not go beyond them, they were good and correct at the time and are so still if we
are speaking of that which Tulasne was discussing. If they have ever given rise to
misapprehensions, it has not been the fault of their author, but of those who did not
understand them,

1 See Bot. Ztg. 1878, p. 481.
? See Pringsheim, Ueber d. Generationswechsel d. Thallophyten (Monatsber. d. Berliner Acad
Dec. 1876), and the literature there cited.

CHAPTER IV.—INTRODUCTION. 127

Tulasne’s doctrine of pleomorphy raised indeed a storm of controversy that lasted for
some time. On the one hand a conservative opposition was naturally to be expected
on the part of those who had already enquired into the species of Fungi, and had become
accustomed to find a species in every detached form with some kind of spore-formation,
disregarding entirely the question of the course of development and genetic connection.
The most aggressive representative of this conservative opposition was perhaps
Bonorden !; others were more cautious and professed to be open to conviction.

On the other hand a misunderstanding of the word pleomorphy Jed men of
enthusiastic character to extravagant conclusions. ‘The explanation of all enigmatical
fungal forms has been reserved,’ it was said, ‘for our decade,’ and the appearance of
two or more different fungal forms in the same spot close to each other, or one after
the other, was regarded at once as a case of pleomorphy of one species and proclaimed
as loudly as possible. Many experiments in culture were also undertaken, and here
too every thing that grew on the spot which had been purposely sown found its place
if possible in the cycle of whatever pleomorphous species the observer happened to
think of. If the character of the substratum was changed in such cultures, the fungal
forms that were obtained were often different; nor could anything be more desired,
for the phenomenon of pleomorphy appeared now to have found its physiological
explanation in the effect of the various physical and chemical qualities of the substratum.
This gave rise to accounts such as the following: Saccharomyces Cerevisiae, the
Fungus of beer-yeast, grows in saccharine fluids in the form indicated by the name.
If it is eaten by flies it developes in them into the primordia of Entomophthora ; these
grow in the dead insects or moist substrata either into the form which bears the last
name (section XLV) or into Mucor (section XLI), but into Achlya (section XL) if the
flies fall into water. Finally Saccharomyces may again be formed from Mucor in
saccharine fluids, &c. &c.? Bail, Hoffmann, and especially Hallier, were the chief
representatives of these pleomorphistic extravagances. Others eager to share the
laurels of these discoverers modestly adopted their views. So far as these obser-
vations possess any historic interest in special cases they will be mentioned in
succeeding sections. Such of them as, like Hallier’s especially, only belong to the
scientific chronique scandaleuse will not be further noticed ; this course is justified by
a critical notice of these matters which appeared some time ago *.

A critical examination of these pleomorphistic aberrations shows at once that the
different forms were not duly discriminated from one another, that no sufficient notice
was taken of the fact that several species are social and are in the habit of appearing
together, or of the possibility that one may take the place of another, or be developed
as a parasite on another, and that strange spores may come from without and mix with
the spores which it is desired to cultivate. It is true that an elaborate provision was
made of bell-jars, glass tubes, and similar appliances to prevent the last source of error.
But even admitting that the apparatus ‘worked with absolute certainty,’ it was
forgotten in using it that unbidden guests might be introduced into the apparatus
when the living objects were placed in it which were intended to be cultivated, and
that in fact it was scarcely possible to prevent their intrusion without a more complete
control of the conditions than is afforded by a non-microscopical apparatus. The
first requisite in a morphological investigation which is also an enquiry into the
history of development, namely the proof of the organic continuity necessarily

1 Abhandl. aus d. Gebiete d. Mycologie, Halle, 1864.—Zur Kenntn. einiger d. wichtigsten
Gattungen d. Coniomyceten u. Cryptomyceten, Halle, 1860.

2 Bot. Ztg. 1856, p. 799.

® Bail, Ueber Krankheiten d. Insecten durch Pilze (Ber. d. Vers. d. Naturforscher zu Königs-
berg) ;—Id. Die wichtigsten Satze d. neuern Mycologie (N. Act. Nat. Curios. 28).

* Jahresber. ii. d. Leistungen u. Fortschr. d. Medicin, herausgeg. v. Virchow u. Hirsch, Jahrg.
2, 1867, Bd. II, Abth. 1, pp. 240-252; reproduced in Bot. Ztg. 1868, p.686. Seealso a clear historic
account by A. Gilkinet, in his work cited at the end of section XLIV (Mucorini),

128 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

maintained at every instant of the successive stages of the development, in virtue
of which the later-formed member begins as a portion of the one which immediately
preceded it, was neglected or even expressly declared to be unattainable’.

It is obvious that criticism could not alter this required condition; and that it
is not at all impossible to carry it out is shown by many investigations, by those
especially which have been made since the appearance of the first edition of this
work, but also by some of a much earlier date. They have left much it is true still
to be done, but they have helped as a rule to clear up the subject, and have done
away with extravagant notions. The scientific method in the conduct of these
investigations was and is obviously that of strict observation of the whole course
of the uninterrupted development, the ascertaining the organic continuity of the
parts of the development at each instant of its course ; this is simply the method
by which we determine that the apple is a product of development of the apple-tree,
and that the tree is produced from the apple; the logic does not change with the
size of the objects or with our apparatus and manipulation. The technical expedients
adopted in applying this method to the Fungi depend on the particular case. The
use of the microscope is generally necessary on account of the small size of the objects
to be dealt with, and we must often follow the development directly under the
microscope, the objects being cultivated on a microscopic slide or in a moist chamber
and on a substratum which is at once sufficiently nutrient and transparent. The
juice of fruit carefully kept pure, decoctions of fresh animal excrement, saccharine
solutions with addition of ash-constituents, or gelatine saturated with the above
fluid matters have proved to be suitable substrata for most artificial cultures under
the microscope. Which is best in each particular case must be determined by
considering the habits of the species. A different method of cultivation to the one
here described must be adopted in the observation of most parasitic Fungi, as will be
shown in Division III. We are indebted to Brefeld especially for the perfecting of
the technical procedure and technical methods in the cultivation of Fungi and par-
ticularly in their cultivation under the microscope, after the guiding principles had been
already indicated by myself in the first edition of this work.

Mistakes may be made and doubtful questions arise even in the use of the most
correct scientific method. Such of these as may be noticed in the sequel must not be
confounded by the student with theories of pleomorphism which are now obsolete.

Section XXXV. As regards the terminology of the subject it may be observed,
that in Fungi as in other plants the development of a new bion very often begins
with a cell, which is detached from the parent or at least ceases to draw its
nourishment from it, and then has the power of further development if the conditions
are favourable. The origin and structure of such cells are very various, and are
characteristic in each particular case. But the general phenomenon remains the
same in all and requires therefore to be indicated by a general expression which
has reference only to it. Such an expression is the word spore (spora) which was
introduced by C. Richard and Link, and has continued to be used ever since in spite
of all attempts to supersede it. At the same time there were good reasons for these
attempts, which rested on the consideration that spores in the sense of Richard and
Link may be produced in a variety of forms on the same species and at dissimilar
places in the course of the development, and that it would be well to distinguish
these forms according to their structure, development, and homologies. Accordingly
A. Braun distinguishes in the chlorosporous Algae, for instance, between spores and

’ See for example Bot. Ztg. 1867 p. 351; also De Bary, Ueber Schimmel u. Hefe, Berlin, 1873.

CHAPTER IV.—INTRODUCTION. 129

gonidia; Tulasne reserves the word spore in many Fungi for certain special forms
of them, and uses a different word for all others. Sachs’ practice is intelligible and
precise’; he sets out from a consideration of the Ferns and Mosses, and reserves
the word spore for the cells produced in the sporophyte or sporocarp and for their
homologues in other plants, while for all such as are not homologous with them he
uses the words gonidia, brood-cells, or some similar term. This plan may be easily
carried out in the very distinct and comparatively limited domain of Ferns and Mosses,
even if the formation of free propagative cells other than spores were not reduced in
these plants to the very smallest possible amount. For the whole field of botany it is
correct but impracticable because the homologies of many free reproductive cells in
the lower Thallophytes are still unknown, and we are still in want of a satisfactory
general expression to denote a distinct and evident phenomenon.

To meet this need we here conform to the vox populi and apply the term spore
quite generally to every single cell which becomes free and is capable of developing
directly into a new bion, without regard to genesis and homology. This definition
excludes from the conception of a spore all oospheres and gametes which require
fertilisation or conjugation, and all cells directly endowed with the male sexual
function. The forms that come under the definition may for convenience sake be
distinguished either by compounds of the word spore or by some special terms, and
these may continue to be simply opposed to the word spore, where this is possible,
as in Ferns and Mosses. The discrimination of spores will depend on different
relationships, according to which the same spore may receive different names, as
happens in all other things. For example we should distinguish—

1. According to sexual relations:

a. spores which are developed from sexually fertilised oospheres, oospores
as Pringsheim happily termed them; or the product of conjugation of
two similar gametes, zygospores.

d. spores not sexually developed.

2. According to structure: swarm-spores and spores that do not swarm (see
above in Chapter III) and many special forms.

3. According to position in the course of development, homology: in many
of the Hepaticae, Scapania nemorosa for example, we must distinguish between
the carpospores (spores simply) which are produced in the fructification and the
structures formed on the leaves and usually termed drood-cells or gonidia, and we
may extend these expressions to all members of the vegetable kingdom which show
the rhythm of development of the main series. Carpospores would thus be the
spores which represent the stage of the development proceeding directly out of the
archicarp or typically concluding its further development, such as the oospores of
the Algae, the ‘spores’ of Mosses and Ferns, the carpospores of the Florideae ;
gonidia would be all other spores, as the tetraspores of the Florideae, most of the
swarmspores of the Algae, the spores of many of the Fungi which are the homo-
logues of these swarmspores and will be described in succeeding chapters ; for these
latter forms the term cozıdia introduced by Fries is in general use.

4. According to the mode of development: thus in the Fungi we have
ascospores (thecaspores), acrospores, &c.

1 Lehrbuch, Aufl. 4.

[4] K

130 DIVISION II.—COURSE OF DEVELOPMENT OF. FUNGI.

In this system of nomenclature the gonidium (3) for example of Oedogonium
and Vaucheria would be a swarm-spore (2); the oospore of these genera would be
non-motile spores, like the zygospore of Spirogyra; but the zygospore of Aceta-
bularia and Botrydium is a swarm-spore, and all oospores are at the same time
carpospores, and so on. The terminology indicated under 3 apparently comes so
near to that of Sachs, that the question may be asked why the latter should not be
accepted as the foundation of the system ; it will be well therefore to point out once
more the fundamental distinction between Sachs’ terminology and that now proposed.
With Sachs spores and gonidia stand side by side as different things; in this work
carpospores and gonidia are special phenomena subordinated to the general con-
ception of the spore. On practical grounds, which have been to some extent
already indicated and which will be further explained below, as under the Basidiomy-
cetes, we cannot do without a word to express this general conception as defined above.
The terminology here proposed is therefore by no means unnecessary, as it might
appear to be if ‘we confine our attention to Ferns, Mosses, and some types of
Algae.

The terminological sketch which has now been given supplies a scheme which is
drawn from actual phenomena forming the general rule, and is applicable to them.
But the highly complex reality is not designed after a single scheme ; there are inter-
mediate forms connecting phenomena which are separated in the scheme, exceptions
to the rule, and no terminology can take all these exceptions equally into account.
In such cases the systematic terminology must necessarily be modified to suit the
particular occasion. This must not be forgotten either here or in connection with
the objects which will be described in the succeeding chapter.

A spore proceeds to a further development if the conditions are favourable.
The commencement of this further development is termed germination. Germina-
tion considered morphologically consists in a very large majority of cases in the
construction of the vegetative body of a unit-bion, as for example when Fungus-
spores put out germ-tubes, as described above in section XXXI. But there are
other cases also. Not only are there those in which the plantlet growing from a
spore remains a rudiment morphologically and in this condition is devoted to
special functions, as in the germinating androspores of heterosporous Pteridophytes
or the pollen-spores of flowering plants, but there are others in which the germinating
spore produces other spores directly as daughter-cells and is entirely expended in
forming them, as was described above in section XXXI in the case of certain Fungi.
In other words in such cases the germinating spore becomes the mother-cell or
receptacle of spores of the next higher generation, a sporangium, as such receptacles
are generally termed. The same object viewed in the different relations specified
above may equally well be called a spore or a sporangium. The same thing may
occur in spores of the most different morphological value, as in the oospores of
Oedogonium and Sphaeroplea and in the gonidia of Cystopus. Spores which are
strictly homologous and come from nearly allied species may develope, some as
sporangia, others as a rudimentary thallus; for example, the gonidia of Peronospora
(section XXXVII), the oospores of Oedogonium on the one hand and on the other
those of Vaucheria. The homology between the spore-forming oospore of Oedogonium
and the sporocarp of a Moss has been already pointed out, and the former may

CHAPTER IV.—INTRODUCTION, 131

accordingly be termed a sporocarp of a very simple kind; here we have the more
comprehensive name implying a more comprehensive relation. If we succeed in
getting a clear general idea of these modes of expression, which necessarily vary
in all cases according to the various points of view, we shall have no difficulty in
finding the term that is suitable to each particular case. It will be well to do this before
proceeding to the consideration of the Fungi which often have so great a variety
of spores.

Historical and critical remarks on the terminology. The word sdore, together
with the related term sporangium and others, is found first in Hedwig (Descriptio
musc. frondos. Lips. 1787), who uses it in the same sense as ‘semen’ and promis-
cuously with it. It was next employed by L. C. Richard (Démonstr. bot. ou Analyse
du fruit, 1808) under the form of sforu/a, and distinctly defined as the small body,
functionally corresponding to the seed, in agamous plants, i.e. plants which have no
embryo. Link (Elem. Phil. Bot. 1829) again introduced the words spore and sporangium,
and adds the word sdorzdium for objects as to which it was not clear whether they
were spores or sporangia; in the Fungi for instance he calls (1. c. p. 359) the acrogenously
formed spores of Penicillium and Aspergillus sporidia. The construction of the true
cell-theory necessarily resulted in the recognition of the fact that spores are repro-
ductive cells. Fries (Syst. Mycol.) generally uses the word sporidium for the spores
of Fungi. Berkeley (Introd. to Crypt. Bot. p. 269) terms endogenously formed spores
sporidia, using the word spores for those that are acrogenously formed. These attempts
to confine the term to special formations have been repeatedly made, but none of them
could meet with decided success for the reason already given in the text. The mode
of expression adopted in section XXXI, which limits the use of the word sporidium
to spores abjointed from promycelia, was introduced by Tulasne in his work on the
Uredineae and Ustilagineae. In species in which different kinds of spores had been
observed, the difference in their position in the course of development, the difference
in their homology as we should now say, has long been clearly recognised and fully
appreciated. The expression spore or sporidium was then limited to those bodies
which could be regarded as homologous with the spores of Mosses, having or appear-
ing, though without sufficient reason, to have an equal ‘dignity’ with them. This
idea was nowhere distinctly expressed, but was nevertheless everywhere implied.
The other spores therefore which made their appearance in the course of develop-
ment ending in the formation of these ‘spores’ required another name. Wallroth
(Naturgesch. d. Flechten, 1825) called them goridia, on the ground, it is true, of some
misinterpreted observations (see Division III), and this term, though occasionally
discarded, has maintained itself or been resumed, as has been partly noticed above.
Kiitzing in the Phycologia generalis (1843), where the account of the matter has some
of the old obscurity, A. Braun (Verjiingung, p. 143) and other writers may be
consulted. In the Fungi Fries (Syst. Mycol. especially Band III, pp. 234 and 263)
substituted the older word conidium for gonidium, clearly implying that the conidia
answer to the gonidia of plants which are not Fungi.

Fries found his especial and most distinct examples of conidia in the Erysipheae
(1. c. 234). Since the conidia are formed by acrogenous abjunction in these Fungi
Fries seems to consider this as their only mode of origin, and to have chosen the
name he gave them from their forming a powder or dust (xovia) on their conidiophores.
He did not mean that all acrogenously abjointed spores were conidia, but all conidia
are acrogenously abjointed. As this view is often in accordance with the facts,
and men are strongly influenced by the word which they have been taught, the
expression used by Fries has unintentionally given occasion to confusion, because
while conidia were said to be of acrogenous origin, spores acrogenously formed were
opposed as conidia to other spores which were formed endogenously, in spite of

K 2

132 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

the fact that the two forms were most certainly homologous. This was the case in
the Mucorini ; see Brefeld, Schimmelpilze, IV. 141, and sections XLI-XLIV below.

It is then quite clear that only the homology and not the mode of origin determines
the nature of the structure in this case, and that conidia may be formed endogenously
and even in an ascus, as well as acrogenously. On these grounds Fries’ venture in
terminology is not a happy one, and it would be desirable to discard the word
conidium and employ gonidium in its stead. The confusion pointed out above would
thus be avoided, and homologous structures would be named alike with one generally
applicable name in Fungi and in all other plants. We need not at the present day
trouble about the special terminology of the Lichens, in which the word gonidium has
hitherto had a special meaning, because as there used it is not only superfluous but
objectionable, as will be shown in Division III. Moreover its application in the sense
explained above is only a restoration of the meaning which its author Wallroth
intended to give it, though under a misunderstanding of the facts.

For further details on this subject the reader is referred to Tulasne’s Carpologie, I.
chapter VI.

Section XXXVI. According to the leading points of view here indicated and
the present state of our knowledge a review of the course of development of the
several groups of the Fungi arranges them in the following manner :—

I. SERIES OF THE ASCOMYCETES.
Peronosporeae (with Ancylisteae and Monoblepharis).
Saprolegnieae.

Mucorini or Zygomycetes.
Entomophthoreae.
Ascomycetes.
Uredineae.

Cr

II. GROUPS WHICH DIVERGE FROM THE SERIES OF THE
ASCOMYCETES OR ARE OF DOUBTFUL POSITION.
4. Chytridieae.
8. Protomyces and Ustilagineae.
9. Doubtful Ascomycetes (Saccharomyces, &c.).
10. Basidiomycetes.
Groups ı-4 have been brought together under the name of Phycomycetes
on account of their close approximation to the Algae.
Groups 7 and 8 in the second category will be considered in connection with
the Phycomycetes ; group 9 naturally in connection with 5, and 10 with 6.

CHAPTER V. COMPARATIVE REVIEW OF THE SEPARATE GROUPS.

PERONOSPOREAE.

Section XXXVII. Of the Peronosporeae some species of Pythium live in
the bodies of dead animals and plants, the greater number as parasites in the tissues
of Phanerogams, and chiefly in the intercellular spaces of the host, though there
are species which, like Phytophthora omnivora, also spread through the cells. The
vegetable thallus consists of copiously and regularly branching tubes, which are
at first non-septate; but aré divided into chambers at a later time when sexual organs

CHAPTER V.—COMPARATIVE REVIEW.—PERONOSPOREAE. 133

are being formed by comparatively few transverse walls disposed at irregular
intervals. Many of the parasitic species put out from the flanks of the intercellular
thallus-tubes numerous small branches, which vary in form according to the species
and penetrate into the interior of the adjacent cells in the form of haustoria (Fig. 8).
The development of the thallus ceases with the formation of sexual organs: female

FIG. 61. Formation of oospores and Processes of fertilisation in the Peronosporeae. J—V/. Pythium gracile. Suc-
cessive states of an ] mature ; to the right of it is an antheridial branch formed but not yet
delimited // antheridi imited by a transverse wall. /// the oosphere has rounded itself off in the oogonium,
and a thin zone of periplasm lies between the oosphere and the wall of the oogonium. // the antheridium has put
out the fertilisation-tube, and a clear receptive spot is visible on the oosphere. Y passage of the gonoplasm from the
antheridi h pore sur! ded by a thick membrane and almost entirely filling the cavity

into the oosp Vi ripe
of the oogonium. VII. Peronospora arborescens; an oogonium with antheridium attached which has put outa fertilisa-
tion-tube. The oosp! is already i d with a thick ; outside it is a comparatively broad zone of peri-
plasm, which is contracting to form the exosporium round the oospore. /—Y/ magn. about 800, V/// 600 times.

organs, oogonia, in each of which one oosphere is formed, and male organs,
antheridia, by which fertilisation is effected in the oosphere which developes into the
oospore. The behaviour of these organs in the process of fertilisation varies con-
siderably in the different genera. It shall be described first in the genus Pythium.
The oogonia of this genus (Fig. 61) are terminal or intercalary spherical

a

FIG. 62. Sexual organs of Peronospora Alsinearum, Casp. a young state. 5 formation of the oosphere and
fertilisation-tube. c after fertilisation ; i d by the p ion, and the fertilisation-tube

unusually thick in this speci 2 antheridi o i Magn. nearly 350 times.

swellings of the thallus-tubes. Their surface remains smooth as it enlarges, or is
rendered spiky in some species by projecting points. Their wall of cellulose is
moderately stout. When they have reached their full size they are delimited from
the thallus by one, or, if their position is intercalary, by two transverse walls, and are
then filled with dense protoplasm containing numerous drops of oil (Fig. 61, Z).

134 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI,

A slowly progressing separation begins in the protoplasm soon after the delimitation ;
the denser protoplasm with the oil-drops moves from the wall to the centre of the
oogonium and aggregates there into a smooth globular body, the oosphere, which
is surrounded by a delicate hyaline pellicle. The space between the oosphere
and the wall of the oogonium continues to be filled with a slightly granular hyaline
protoplasm, the ferzplasm, which may easily be overlooked (Fig. 61 JI, III).
About the same time that delimitation of an oogonium takes place the formation
of at least one antheridium begins close to it (Fig. 61; see also Fig. 62 2). The
antheridium is in the simplest case a younger sister-cell of the oogonium formed
by delimitation of the contiguous portion of its parent-filament; terminal oogonia
are therefore placed upon it as on a stalk-cell, which may either remain straight
(Fig. 67) or have a characteristic curvature. In another series of cases the anthe-
ridium is the terminal cell of a special branch of the thallus, which grows towards
the oogonium and attaches itself firmly to it; and this branch either springs from
the same filament as the oogonium for which it is provided and close to it, bending
over towards it, or it proceeds from some other branch of the thallus lying near
the one which bears the oogonium. These circumstances of form and insertion vary
sometimes in different species, sometimes in different individuals; so also the
number of antheridia attached to one oogonium, which are often two, but in P.
megalacanthum may be as many as six.

The cell-wall of the antheridium is not thickened, and its protoplasm is at
first parietal and granular and not distinguishable from that of the thallus. When
the oosphere has been formed in the oogonium, the antheridium sends a delicate
cylindrical or conical tube-like process, the /erzilisalion-tube, from the part of its
surface which is in contact with the oogonium into the interior of the latter; the
tube grows till it reaches the surface of the oosphere, attaches its apex firmly to
it and subsequently opens at that spot. Soon after the formation of the tube the
protoplasm becomes differentiated in the antheridium; the larger and denser
granular portion moves into the centre of the cavity, forming there an irregular and
somewhat indistinct strand, the gonoplasm, while a thin layer (periplasm) remains on
the wall of the cell. Then the gonoplasm passes slowly in most cases through the
fertilisation-tube which has opened in the meanwhile into the oosphere, the transference
of the whole of the gonoplasm being completed in from one to two hours. If there
is more than one antheridium, they all usually, but not always, empty their gonoplasm,
one after the other, into the oosphere. At least one antheridium discharging
its contents in this way is invariably present on normal specimens, that is to
say, on those which develope an oosphere. The function of the antheridium is
fulfilled when it has discharged its contents. The oosphere at once becomes invested
with a thick cellulose-membrane and ripens into the oospore (Fig. 61 ZZ/Z-VI). Inthe
genus Phytophthora the process is in every respect the same as in Pythium, except
that only a very minute quantity of protoplasm passes over into the oosphere through
the fertilisation-tube, and this portion is not distinctly separated beforehand. Phyto-
phthora omnivora has one noticeable peculiarity; the oogonium and its antheridium
are formed almost simultaneously beside one another and develope in connection
with one another. In Peronospora again such phenomena of development and
fertilisation as can be observed are essentially the same as in the two preceding

CHAPTER V.—COMPARATIVE REVIEW.—PERONOSPOREAE. 135

genera, but the passage of the protoplasm into the oosphere cannot be directly seen,
and the periplasm in the oogonium is much denser and more copious (Figs. 61
VII and 62). Lastly the species of Cystopus behave like Peronospora in every
point that can be distinctly seen, but the details in this genus require further
investigation.

In Pythium, Phytophthora, and Peronospora the constituents of the protoplasm
of the oosphere are rearranged as it begins to mature, and the structure of the ripe
oospore is of the following kind (Fig. 61 V7; see also section XL, Fig. 69 ¢). The
membrane becomes thicker and is composed of two main layers, an episporium
and an endosporium ; the latter usually swells up into a jelly in water in Peronospora,
and both show the reaction of cellulose. The original oil-drops are dissolved, but
their substance has collected into a comparatively large sphere pale on the outside
and of weak refringent powers occupying the centre of the spore-cavity. The
space between it and the membrane is either filled with protoplasm containing fine
uniformly disseminated granules, or a layer of protoplasm of this kind lines the wall,
but is separated from the central sphere of fatty matter by a limpid zone. When the
spore is ripe a round or elongated and perfectly pellucid spot makes its appearance
in the parietal layer close to the membrane. The nature of this spot has not been
clearly ascertained ; it is perhaps a nucleus, which is visible as a transparent central
body when the oosphere is first formed and afterwards disappears from that position.

In Pythium and Phytophthora the periplasm cannot be seen to take part in the
maturing of the oospore; it surrounds it in the form of an inconspicuous sparingly
granular mass. In Peronospora (Figs. 61 V//, 62) on the contrary it developes
into a thick membrane usually of a deep brown colour, the exosporzum, which forms
a closely fitting envelope round the ripe oospore, and has a structure and surface-
sculpturing characteristic of each species. In this point Cystopus closely resembles
Peronospora, but the structure of the ripe oospores still wants a more thorough
examination. The wall of the oogonium undergoes no special changes as the
oospore matures; in most cases it becomes decomposed; in some of the Perono-
sporeae it becomes strongly thickened at the time of the formation of the oosphere,
and may persist after the latter is ripe.

The oospores remain dormant for some time and then germinate under water;
in some species they put out a germ-tube, which on a favourable substratum grows
at once into a thallus which produces oospores in the same way as the mother plant; this
is the only form of germination in Pythium de Baryanum, Artotrogus, and Peronospora
Valerianellae. In other species the whole germinating oospore always becomes
a sporangium ; its protoplasm divides simultaneously into from several to many
spores which swarm out of a previously formed tubular process, and after a short
period of movement each developes like the spores of the first-mentioned species into
a thallus that produces oospores. Cystopus candidus (Fig. 63) is an instance of this
kind. In a third group of species some oospores show the one, some the other mode
of germination, sometimes apparently under the influence of external causes; this is
the case with Pythium vexans and P. gracile. A fourth group containing Pythium
proliferum and Phytophthora omnivora exhibits a mode of germination which
is to some extent intermediate between the first and second kind and which will
be described further on.

136 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

The above phenomena close the cycle of development and in some species the
course of development is actually limited to them; many observations at least have
failed to detect anything further, for example in Pythium vexans and Artotrogus.
We may therefore conclude that the essential points in the life-history of the whole
group are confined to these phenomena.

But in most species there is this difference, that the course of the development
is extended by the intercalation of numerous propagative cells, gonidia. In some
cases indeed the formation of gonidia is actually a necessary part of the entire
development; the germ-tube which proceeds from the oospore developes into

oF

> FIG. 63. Cystopus candidus. A mycelium with young ia og. B jum og with oosp os and antheri-
dium as. C mature ium og, os, D ripe pi in optical longitudinal section. Z, F, G formation of
swarm-spores from oospores; Zendosporium. Magn. 400 times.

a small rudimentary plant, which we may call a promycelium (see on page
111), and this produces a few gonidia and then dies, while the gonidia give
rise to new perfect fertile plants. This is the case with Phytophthora omnivora
and Pythium proliferum which represent the intermediate mode of germination
mentioned above. A very large majority of species, the two last-named among the
number, form gonidia, not or not only in the way just described as terminal
members of a short-lived alternate generation, but.as accessory products of every
normally developed thallus; the gonidia are usually produced in such large quan-
tities as to further the propagation of the species to an enormous extent by their
germination, and they have such characteristic forms, that the characters of species,

CHAPTER V.—COMPARATIVE REVIEW.—PERONOSPOREAE, 137

and especially of genera, may be taken chiefly from the gonidial formations, while the
few species which have no gonidia are not easily classified.

The main features in the formation of gonidia in the genera and subgenera of the
Peronosporeae are as follows :—

Pythium. A persistent cell, usually the terminal cell of a branch, is delimited by a
transverse wall and becomes a spore-mother-cell (sporangium). The gelatinously
thickened wall at its apex suddenly expands into a thin-walled spherical vesicle, and
into this at the same moment the whole of the protoplasm of the cell, which is hitherto
undivided or has only shown transitory beginnings of division, streams rapidly, within a
few minutes’ time at most; there it breaks up at once-into a number of swarm-spores,
which issue from the delicate swelling vesicle and finally germinate. The sporangia in
some species are of the same form as the gonidia of Phytophthora (Fig. 64),—round or
ovoid vesicles prolonged at the extremity into a neck or beak, in the apex of which the
swarm-spores are formed ; in others any portion, and often a very long portion, of the
cylindric filamentous thallus-tube is delimited to form the sporangium, and its apex in
which the swarm-cells are formed is then a small knob-like enlargement at the
extremity of a branch, but is
not otherwise distinguished by
any particular form. There is
usually no strict regularity dis-
cernible in the arrangement of
the sporangia. In species with
vesicular sporangia the fila-
ment which bears them often
grows on into the empty spor-
angium from the point of its
insertion, or through its entire
length; and then forms a new
terminal sporangium as in 4
Saprolegnia (see p. 46). A
certain kind of regular ar-

rangement and succession oc- FIG. 64. Phytophthora infestans. Extremities’of two simple sporophores. a for-
] E i f the fir idi: i a «a:
curs in one species only, mation of the first gonidia on the tip of each branch. 4 two ripe gonidia on each

branch, a third beginning to form. Magn. about 200 times,

Pythium intermedium, and in
two ways, sporangia being either formed sympodially and successively on a branch
of the thallus and separated by elongated portions of the thallus, as is described on
pages 47 and 65, or by serial successive abjunction (see p. 66). In the same species
the sporangia with their wall of delimitation are easily and abundantly shed from their
sporangiophore, so that they may equally
well be called spores, and the name is
still further justified by the fact that
under certain circumstances they may
put out a germ-tube immediately without
forming swarm-spores. P. de Baryanum
also often forms spores (gonidia), which
have the same form as the sporangia,
in place of sporangia, but germinate
directly by the emission of a tube. : ore

Phytoplithora (Figures 64, 65). emails teure « Sormetm I wove
Branches of the thallus either solitary or forest and bank (eres in the motile ime one
growing side by side in small tufts con-
stitute peculiar gonidiophores and form gonidia. They generally send out a few branches
monopodially disposed, and each of these secondary branches or the unbranched
gonidiophore forms a number of gonidia sympodially and successively at elongated

138 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

intervals; accidental and unimpertant. deviations from this plan are sometimes but
rarely observed. The gonidia are usually abjointed as spores, and in germination,
which takes place under water, become swarming sporangia. The swarm-cells are not
formed in the same way as in Pythium but inside the original membrane of the
sporangium, from which they issue through an aperture at the apex. As a frequent
exception the germination of the spores abjointed from the gonidiophores is direct by
the growth of a germ-tube.

Peronospora. Gonidiophores, disposed as in Phytophthora and regularly and usually
copiously branched, give off by abscision a single spore at the extremity of every branch
and then die away. The gonidia germinate in water and the process varies in different
species.

(a) In a number of species they behave as in Phytophthora.

(4) In the majority of species they send out a germ-tube directly either from their
extremity or laterally, and never form swarm-spores.

(c) In the plasmatoparous species mentioned on page 112 there is an intermediate
form between (a) and (4) which is especially allied to the variety of (4) in which there
is an apical germ-tube. ‘

Cystopus. Gonidia are abjointed in along simple chain from the apex of club-shaped
branches arranged in tufts (Figs. 66 and 33). The branches are set close together and
parallel to one another and form broad hymenia (see section XII). The gonidia in
germination form swarm-spores only ; the terminal member alone of each chain, except
perhaps in C. candidus, may behave otherwise ; it has a thicker wall than its younger

. sisters and is poor in proto-
plasm and incapable of ger-
mination. Tulasne’s state-
ment! regarding the peculiar
form of the terminal members
in C. Portulacae and its send-
ing out a germ-tube has not
been confirmed. As the goni-
dial chains of Cystopus begin
to develope beneath the
epidermis of phanerogamous
plants and afterwards force
their way through it, the
thick-walled terminal mem-
bers evidently serve to protect
their younger sisters behind
them.

The other genera of the
nating, i. e. forming swarm-spores ; the protoplasm is already divided. D escape of Peronosporeae as at present
ecm A an re te nae cman Fine ne im determined. entirely agree
trated into a stoma of Lepidium sativum ; it is the inner surface of the stoma or with those described above
epidermis which is seen, and the spores from which the germ-tubes come are on the E a 5 .
outer surface at the stoma. Magn. 400 times. in the points with which we

are here concerned.

FIG. 66. Cystopus didus, Lév. B idioph C gonidia in the act of germi-

In all the above cases each germ-tube proceeding from a gonidium either
directly or through the intervention of swarm-cells developes on a suitable substratum
into a thallus, which first forms gonidia and ends with the production of oospores.
If the conditions are less favourable the plant forms often a luxuriant thallus, and
abundance of gonidia through an unlimited number of generations proceeding from

1 Second Mémoire sur les Uredinées in Ann. d. sc. nat. ser. 4, IJ, p. r10.

CHAPTER V.—COMPARATIVE REVIEW—ANCVLISTEAE. 139-

gonidia, but does not produce oospores. This may occur in all species; and among

those which have been more thoroughly examined there are two, Phytophthora

infestans and Pythium intermedium, which, as far as accurate observation extends,

have lost the power of forming oospores, and produce gonidia only (see p. 125).
Literature of the Peronosporeae.

DE Bary, Recherches sur le développement de quelques Champignons parasites (Ann.
d. sc. nat. ser. 4, XX, where the older literature, especially Tulasne’s works, is
cited ;—Id. Beitr. z. Morph. u. Phys. d. Pilze, II;—Id. Beitr. IV, Unters. ü.
d. Peronosporeen u. Saprolegnieen, &c.;—Id. Zur Kenntn. d. Peronosporeen
(Bot. Ztg. 1881). Further notices of works are given in the two last-mentioned
treatises.

PRINGSHEIM in Jahrb. f. wiss. Bot. I (Pythium).

M. CoRNU, Monographie des Saprolegniees (Ann. d. sc. nat. ser. 5, XV, 1872) ;—Id.
in Comptes rendus, XCI and XCII, 1880, 1881 ;—Id. Observations sur le Phyl-
loxera et les parasitaires de la vigne. Etude sur les Peronosporées, II. Le
Peronospore des vignes, Paris, 1882 (Acad.).

SCHROTER, Peronospora obducens (Hedwigia, 1877, p. 129) ;—Id. Protomyces grami-
nicola (Hedwigia, 1879, p. 83).

FARLOWw, On the American Grape-vine mildew (Bullet. of the Bussey Institution, 1876,
P- 415).

A. MILLARDET, Le Mildiou, Paris, G. Masson, and in Journal d’Agriculture pratique,
1881, I, No. 6, and 1882, II, No. 27.

A. ZALEWSKI, Zur Kenntn. d. Gattung Cystopus (Botan. Centralbl. 1883, No. 33).

:

ANCYLISTEAE.

Section XXXVIII. The Ancylisteae are a small group of small plants,
parasites on fresh water Algae and nearly related to the Peronosporeae and especially
to the genus Pythium. The tubular thallus is at first unsegmented in all the
members of the group and is divided into cells by transverse walls for the purpose of
forming oospores; some of these cells swell into vesicles and become oogonia, the
rest continue narrow and answer to the antheridia of Pythium. The two kinds of
organs either lie side by side in the monoecious thallus, somewhat as in Fig. 67, as is
the case in Myzocytium globosum of Cornu ; or they are dioeciously distributed, some
plants forming only oogonia, others only antheridia, and the antheridia send out a
tubular filament by means of which they unite with the oogonia, as in Lagenidium
Rabenhorstii of Zopf, which lives in Spirogyra, and in Ancylistes of Pfitzer, a parasite
on Closterium. In these plants there is no distinct differentiation of oosphere and
periplasm previous to the formation of oospores ; it appears, on the contrary, that the
partition-membrane between the antheridium and oogonium is first perforated, and
the whole of the protoplasm of the antheridium passes into the oogonium, and it is
not till then that the combined protoplasm withdraws from the wall of the oogonium
and developes into the spherical thick-walled oospore. The more special structure of
the oospore varies with the species. Their germination has not been observed. No
organs are known in Ancylistes Closterii except those just mentioned, the propagation
of the plant being effected by the thallus-tubes growing from one closterium-cell to
another and forcing an entrance into it. The other forms named above produce
zoospores after the manner of Pythium, and from sporangia which originate like the
oogonia by transverse segmentation of the thallus. The group requires more

140 DIVISION II,—-COURSE OF DEVELOPMENT OF FUNGI.

thorough investigation; Pringsheim’s Pythium endophytum! and Schenk’s Achlyo-
geton? are certainly very near it.
Literature of the Ancylisteae.
CORNU, Monogr. des Saprolegniées in Ann. d. sc. nat. ser. 5, XV, and im Bull. soc. bot.
de France, XVI (1869), p. 222 ;—-Id., cited in Sachs, Traité de Bot. translated by
Van Tieghem, p. 328.—See aiso Schenk, Ueber contractile Zellen, Wiirzb. 1858, p. 9.
ZoPF in Bot. Ztg. 1879, p- 351.
PFITZER in Monatsber. d. Berlin. Acad. 1872, p. 351.

MONOBLEPHARIS.

Section XXXIX. The aquatic genus Monoblepharis with three species, which
at present has been examined only by Cornu’, is related to the Peronosporeae.
These plants, according to Cornu’s short and somewhat incomplete description,
resemble the Pythieae in their vegetative structure and in their mode of life. They
form on their thallus sporangia with swarm-spores, and the latter originate and
escape, not in the manner of
Pythium, but in that of Phyto-
phthora, &c. and have only one
cilium. Oogonia and anther-
idia are terminal or intercalary
on the branches of the thallus ;
their disposition, which varies
in the different species, agrees
with that of some species of
Pythium ; Fig. 67 shows it in
Monoblepharis sphzrica. The
points in which M. differs from
Pythium appear in its further
development. Firstly, the whole

FIG. 67. Monoblepharis sphaerica, extremity of afi bearing an ium Of the protoplasm of the oogo-
oand an antheridium a. x. before the formation of the oosphere and spermatozoids. . j A =
2 ns rn which is an ee ven van Krisen
After Cornu. Magn. 800 times. globules is transformed into the

oosphere without separation of
periplasm and with diminution of volume, and as this takes place the wall of the
oogonium opens at its upper end. Secondly, a few swarm-cells (spermatozoids)
are formed by division of the protoplasm in the antheridium; the spermatozoids
escaping through an aperture in the wall of the antheridium move with a gliding
motion over the wall of the oogonium, till one of them finds its way through the
aperture to the oosphere and coalesces with it. The oosphere is thus fertilised and
an investing membrane is formed, which subsequently becomes strongly thickened
and rough with warts on the outer surface; in this state the body is a resting oospore,
the further development of which is unknown, but can hardly differ from that of the
Peronosporeae.

1 Jahrb. f. wiss. Bot. I. ? Bot. Ztg. 1859, p. 398.
® Ann. d. sc. nat. ser. 5, XV, 1872.

CHAPTER V.—-COMPARATIVE REVIEW.—SAPROLEGNIEAE. I4I

SAPROLEGNIEAE.

Section XL. These plants, which live on dead organic bodies in water, closely
resemble the Peronosporeae in the course of their development and to some extent
also in habit; they are most of them of large growth, with tubular hyphae 1-2 cm, in
length standing out from the substratum and slender rhizoids spreading through it
(Fig. 68). They differ from the Peronosporeae chiefly in the development of the
oosphere and in the circumstance that in all the better-known species the antheridia
though existent do not perform their fertilising function, or are entirely wanting.
The oogonia are formed on branches of the thallus-tubes as in the Peronosporeae,
and the whole of the fatty protoplasm is transformed into a single oosphere, or divides
into several portions which become so many round oospheres, without any separation
of periplasm. The number of oospheres varies in both species and individuals. Most
species have as a rule several oospheres in an oogonium, some have as many as 30 or
40 or more, feeble specimens often only
2-4. The oospheres ripen into oospores,
which in most cases have the same struc-
ture as those of the Peronosporeae, es-
pecially the Pythieae (Fig. 69 C). A few
species are unlike the rest in this respect.

Like the Peronosporeae many Sapro-
legnieae have antheridia ; in a few species
only (Saprolegnia hypogyna, Pringsh.) the
antheridium is the stalk-cell which bears the
oogonium, as in Monoblepharis (Fig. 67):
usually it is the obliquely club-shaped or
cylindrical terminal cell of slender branches
which grow one or more in number to-
wards the oogonium and apply themselves ;

‘ ER FIG. 68. Achlya prolifera. A germ-plant twenty-four
elect Wei ab Thee Teed en ne re mee
branches spring, according to the species, — branches of the primary rhizoid which have penetrated into
either from the branch of the thallus Br ra tae as tie Saba Hana GE an aoe ete

J sequently fertile branches.
that bears the oogonium to which it at-
taches itself, and then usually close to it
(androgynous forms; Fig. 69 A, 2); or from special branches of the thallus which
do not bear oogonia (diclinous forms); cases intermediate between the two extremes
are of comparatively rare occurrence. The antheridial branches apply themselves to
the oogonia. The first appearance of the lateral branches and the delimitation of
the antheridia take place before the formation of the oospheres. When these are
formed, the antheridia usually send out 1, 2, or 3 delicate tubular processes which, like
the fertilisation-tubes of Pythium, grow into the oogonium and in the direction of the
nearest oosphere and apply their apex firmly to it; but they do not open, and
nothing like a discharge of their protoplasm has ever been observed (Fig. 69 2); on
the contrary they generally continue to elongate after their first contact with an
oosphere and grow over its surface and not unfrequently beyond it. When there

142 DIVISION II—COURSE OF DEVELOPMENT OF FUNGI.

are several oospheres present the tubes often grow from one to another, and even
form branches which grow up to and past different oospheres, and sometimes even
pierce through the wall of the oogonium and pass outside it; but they always remain

FIG. 69. A—C. Achlya racemosa, Hildebr. 4 end of a
fertile branch with an empty sporangium at s surmounted by
a head of gonidia out of which most of the spores have already
swarmed away. Beneath it on short lateral branches are
three oogonia with antheridial branchlets ; 2 before the deli-
mitation of the oogonium and antheridia; 4 and c in the same
stage as 8; both oogonia have two antheridia, and 2 has six,
c seven ph B jum with two oosph and an
antheridium resting on it; a fertilisation-tube from the an-
theridium has reached the surface of the nearest oosphere.
Caripe oospore. D—E. Achlya polyandra. Danoogonium
with three germinating oospores about five weeks after
maturity. The short germ-tubes of two of the oospores are
protruding from the oogonium, the third lies bent inside it.
The oogonii ins also two oosp which have not
yet germinated, one of which is shown in the figure. Ea
germinating oospore which has formed a small sporangium
with a head of spores, 4 magn. 145, B and C 375, D and
E 225 times.

closed.and die in the course of ı-2 days
while the oospheres are maturing. The
short tubes of Aphanomyces scaber are the
only ones Which I have examined which
never showed this luxuriance of growth;
they apply their apex firmly to the oosphere
which in this species is solitary, and re-
main in that position without change till
the oospheres ripen in 2-3 days’ time.
These facts show that the antheridia and
fertilisation -tubes of the Saprolegnieae
must be considered to be homologous with
those of Pythium and that they may be
called by the same name: but there is no
ground for regarding them as really fer-
tilising organs; for while in some species,
as Achlya polyandra and Saprolegnia
monoica, their mode of formation is always
such as has just been described, there are
other species in which the same plant may
have these antheridia with their fertilisa-
tion-tubes and at the same time antheridia
without tubes, or oogonia without any an-
theridia (Aphanomyces scaber, Saprolegnia
hypogyna); and lastly there are species
or races, extremely like those named above
in other respects, which very seldom or never
form antheridia. In all these cases the
formation of oospheres and oospores does
not vary in the smallest detail.

The ripe oospores remain dormant dur-
ing a time which varies from some days
to some months according to the species,
and germinate in the same forms as in
the Peronosporeae (Fig. 69 D, Z). All
the different forms of germination de-
scribed in the Peronosporeae have also
been observed in most of the species of
Saprolegnieae which have been examined,
the form varying according to the ex-

ternal conditions, especially those of nutrition; but in some species certainly only
one or the other form of germination has been observed. In a new species, Aplanes
Braunii, the whole course of the development, as far as my observations go, is usually

CHAPTER V.—COMPARATIVE REVIEW.—SAPROLEGNIEAE. 143

limited to the direct development of a thallus from the germ-tube which proceeds
from the oospore, and to the formation of oogonia, oospores, and antheridia on it.
There is usually no formation of gonidia in this species.

In all other cases the fully-grown thallus which forms oospores also produces
gonidia; the production is comparatively scanty and uncertain in Achlya spinosa,
abundant usually in all other species. The gonidia are formed first, the oospores
appearing during a later period of the development, partly on the same main branches
of the thallus as the gonidia, partly on special branches. Here, as in the Peronosporeae,
and evidently as the result of external causes,
the gonidia are produced in much greater
quantities than the oospores, and they are them-
selves the most effective in the propagation of
the species. At the same time no species in the
Saprolegnieae is known to be without oospores.
The gonidia in all species, except the Aplanes
mentioned above, are normally swarm-spores and
are formed either in the germinating oospore, or
in sporangia, which are usually of some size and
borne on branches of the thallus. The species
with swarming gonidia have occasionally resting
gonidia also, but their appearance is accidental
and exceptional. The genera of the Sapro-
legnieae, like those of the Peronosporeae, are
chiefly distinguished by the sporangia and the
formation of the swarm-cells in them.

The genera Saprolegnia, Achlya and Dictyu-
chus, when well developed have club-shaped
sporangia, the protoplasm of which divides into
numerous spores arranged in many rows (Fig.
70 A). Very feeble specimens form only one
row of spores, and there is scarcely ever more

than one row in the long narrowly cylindrical
sporangia of Aphanomyces. (See section XVIII

a, P- 74.)
The distinguishing mark of Saprolegnia is
that the spores ate in the motile state as they nn ie nee sores Bone saictiues

issue from the sporangium, and that the branch after ejection of the gonidia, a few only remaining

- = in the sporangium. The larger number are grouped
of the thallus which bears the sporangium grows at its mouth in a hollow sphere 2 and have become
through it when it has discharged its spores. away navdeg dir elle 0 betind tear an
Achlya and Aphanomyces are known by the about 300 times.
discharged spores collecting into little heads form-
ing the hollow spheres described on page 108, which they subsequently leave when they
begin to swarm (Figs. 69 A, 70 B). Another exceptional fact besides the forming of
these heads is observed in some species of Achlya and according to Sorokin! in
Aphanomyces also; the spores are invested with a membrane of cellulose in the
place in which they are formed inside the sporangium, and afterwards burst through

this membrane and through the lateral wall of the sporangium to swarm. A number

1 Ann. d. sc. nat. ser. 6, II (1876), p. 46.

144 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

of species which agree with Achlya in other respects have the last named peculiarity
alone, and their spores do not collect into heads; these are included under the generic
name of Dietyuchus. Some histological details will be found in section XVIII.
The formation of swarm-spores in the germination of the oospores agrees in every
known instance with the character assigned to the genera, but has not yet been observed
in Dictyuchus.

Aplanes, a new genus, identical probably with Reinsch’s Achlya Braunii, very
rarely forms gonidia on the developed thallus, but more often in the germination of
the oospores. The gonidia are formed as in other genera; in the germination of the
oospores either directly in the cavity of the oospores, or in a single row in sporangia
on short-lived dwarf plants. They put out short germ-tubes at once in the place
where they are formed, nor have I ever been able to perceive any appearance of
swarming.

Resting gonidia. In old tufts, those of Saprolegnia especially, it not unfrequently
happens that the thick thallus-tubes become broken up by transverse walls into cylin-
drical, barrel-shaped, or inflated spherical cells, which are sometimes thick-walled and
always rich in protoplasm. In some species, and especially according to my own
observation in Achlya prolifera, these cells may be very large and spherical, unusually
full of protoplasm, and abjointed serially and successively at the end of a tube 1;
All such cells may under favourable circumstances—in pure water containing free
oxygen, and when supplied with suitable food—either develope directly into new
thallus-tubes or become swarm-sporangia (the resting sporangia of Pringsheim).
They are not, as far as we know, characteristic of particular species, but simply
resting states which frequently make their appearance under the influence of external
causes.

The deviation in the structure of some oospores from the ordinary type has
been described by me at length in another work? It occurs in a few species of
Achlya (A. polyandra and A. prolifera), in Dictyuchus clavatus and in an undescribed
Saprolegnia, and is not generally characteristic of any of the genera in question.

Leptomitus lacteus and L. brachynema are imperfectly known forms, belonging
probably to the Saprolegnieae, with their thallus-tubes constricted at intervals and
with swarm-spores formed in a similar manner to those of Saprolegnia; with respect
to Cornu’s genus Rhipidium the author’s short preliminary description leaves it
uncertain whether its place is here or with the Peronosporeae near Pythium.

Controverted points. Pringsheim has recently put forth some views which if
correct would require a modification to some extent of the account here given of the
Saprolegnieae, but only so far as concerns the possibility of a fertilisation of the
oospheres by the antheridia,

Pringsheim claims the office of fertilisation for some small portions of protoplasm
with amoeboid movements, which are supposed to make their way through the closed
‘wall of the fertilisation-tube and to pass into the oosphere. Pringsheim has never
seen this take place ; he only suspects it on the evidence of some stained preparations,
which seemed to show a possible open communication between the protoplasm of
the oosphere and that of the antheridium, and of a peculiar phenomenon observed
in the antheridia of Achlya racemosa, the account of which must be read in the ori-
ginal publication, but which has certainly nothing to do with the process of fertilisation.
His observations moreover refer to other species than those specially described above.
If there is really an open communication in those species between the protoplasm of the
antheridiam and oosphere, which, as has been said, is extremely doubtful, we must
admit a fertilisation in their case, and in the mode already described in Pythium

1 Walz in Bot. Ztg. 1870, t. IX, Fig. 20. ? Beitr. IV, p. 69.

CHAPTER V.—COMPARATIVE REVIEW.—MUCORINT. 145

and Phytophthora. All beside remains untouched ; especially the absence of sexuality
in the species, forms, and individuals, which have no antheridia producing fertilisation-
tubes.

For the details of these disputed points the reader is referred to the publications,

which are cited at the close of the following list and which have appeared since the
year 1882.

Literature of the Saprolegnieae.
N. PRINGSHEIM, Entwicklungsgeschichte d. Achlya prolifera (N. Acta Acad. Leo-
poldin. Carolin. 23, I, pp. 397-400).
A. DE BARY, Beitr. z. Kenntn. d. Achlya prolifera (Bot. Ztg. 1852, p. 473).
Both these works contain also a record of the earlier copious literature of the subject.
PRINGSHEIM, Beitr. z. Morph. u. Systematik d. Algen, II ;—Id Die Saprolegnieen in
Jahrb. f. wiss. Bot. I, 1857, p. 284 ;—Id. Nachträge z. Morphol. d. Saprolegnieen
(Jahrb. f. wiss. Bot. II, 1860, p. 205) ;—Id. Weitere Nachträge, &c. (Jahrb. f. wiss.
Bot. IX, 1874, p. 191).
DE Bary, Einige neue Saprolegnieen (Jahrb. f. wiss. Bot. II, p. 169) ;—Id. Beitr. 2.
Morphol. und Physiol. d. Pilze, IV (1881).
HILDEBRAND, Mycolog. Beitr. I (Jahrb. f. wiss. Bot. VI, 1867, p. 249).
LEITGEB, Neue Saprolegnieen (Jahrb. f. wiss. Bot. VII, 1869, p. 357).
K. LINDSTEDT, Synopsis d. Saprolegniaceen (Diss. Berlin, 1872).
M. CORNU, Monographie der Saprolegniées (Ann. d. sc. nat. ser. 5, XV); see page 139
above.
P. REINSCH, Beob. ü. einige neue Saprol. (Jahrb. f. wiss. Bot. XI, 1878, p. 283).

M. BÜSGEN, Entwickelung d. Phycomycetensporangium in Diss. and Pringsheim’s
Jahrb. XIII, Heft 2, 1882.

N. PRINGSHEIM, Neue Beobacht. ii. d. Befruchtungsact v. Achlya u. Saprolegnia
(Sitzungsber. d. Berlin. Acad. 8 Juni, 1882) ;—Id. in Jahrb. f. wiss. Bot. XIV,
Heft 1.

DE Bary in Bot. Ztg. 1883, Nr. 3.

See also Zopf and Pringsheim in Bot. Centralblatt, 1882, Nr. 49, 1883, Nr. 25 and 31.
Some smaller treatises have been already noticed in the text and in my publication
of 1881 cited above.

MUCORINI.

Section XLI. The Mucorini or Zygomycetes agree very nearly both in
structure and in the course of their development with the Peronosporeae and
Saprolegnieae, but there is this essential difference between them, that, instead of the
oospores which have just been described in the two latter groups, the Mucorini form
zygospores, which are typically produced by the coalescence, conjugation, of two nearly
or perfectly similar cells of separate origin (gametes). The formation of zygospores
is not the only form of propagation in any known species of the group. On the
contrary they all produce gonidia as well, and the gonidia in some species have
considerable variety of form owing to complicated life-conditions ‘and adaptations,
and in all are much more abundant than the zygospores. Even in species where the
zygospores are comparatively abundant the gonidia predominate to such an extent,
that they propagate the species unaided through many successive generations,
the zygospores on the whole rarely arriving at their full development. In some
species the zygospores are great rarities; in a whole series of forms, which it cannot
be doubted are in other respects closely related to the species which produce

[4] L

146 DIVISION IL—-COURSE‘ OF DEVELOPMENT OF FUNGI.

zygospores, these organs have never yet been observed ; and since some of the species
have been frequently and carefully examined, it may perhaps be conjectured that they
do not at present produce zygospores, but only gonidia.

The members of the group of Mucorini, with the exception of the doubtful
genus Zygochytrium, which will be considered in a later page, are plants of the dry
land, and grow most of them on dead organic bodies (especially animal excrements),
some being parasitic on other Mucorini.

A spore gives rise to a mycelium having the form of a much-branched unicellular
tube, as may be seen most readily by cultivating the plant in drops of fluid or in
mucilage on a microscopic
slide (Fig. 71 2), and it
is not until gonidiophores
begin to be produced that
the tube is in a condition to
form the transverse septa
which then usually appear in
it. The Zypical gonidiophores
(Fig. 71 g) begin after one
or more days’ time to shoot
upwards from the mycelium
which has spread in the
substratum; they appear in
the form of branches which
are usually erect, and, like
the parent-tube, are at first
without transverse septa. In
some species, as Mortierella
and Syncephalis, they are al-
most microscopically small ;
in most cases, however, they
are of considerable size,from
one to several centimetres
in length, in Phycomyces
10-30 cm. Older or im-
perfectly nourished mycelia
may subsequently produce
a fresh crop of accessory

Nae

=

N

I

FIG 71. B. Phycomyces nitens. Plants three days old grown from a gonidium in rel .
gelatine with decoction of plums; the mycelium 2 has spread horizontally, g a gonidio- gonidial Sor MS. But in all
‘phore. A,C, D Mucor Mucedo highly magnified. 4 sporangium in optical longitu- = .
dinal section. In C the germinating zygospore z is borne on suspensors; K germ-tube, SPECIES which have been

it D j i bb slightly, 4, C and D more =
thoroughly examined the
mycelium under favourable
circumstances completes its development by forming zygospores. Finally the
ripe zygospore, after remaining dormant for several months, puts out one or
more strong germ-tubes, which develope at once without mycelial formation
into the typical gonidiophores which are characteristic of the species (Fig. 71 C).

The gonidia of every species invariably produce, if the conditions are suitable, a

& 5 aa g P
highly magnified. After Brefeld from Sachs’ Lehrbuch.

CHAPTER V.—COMPARATIVE REVIEW.—MUCORINI. 147

mycelium which displays the characters and follows the course of development here
described. Hence a regular alternation of generations is observed in the life-history
of these plants; typical gonidiophores are formed directly and normally from the
germinating zygospore, and their products germinate and form a mycelium which
produces gonidia again and ultimately zygospores. This course of development may,
it is true, be so far disturbed, that the germ-tube which proceeds from the zygospores,
if it is hindered from forming gonidia directly but is well supplied with food, as when
it is artificially sunk for instance beneath the surface of a nutrient solution, may
develope into a mycelium which does not become sporiferous till after the lapse of
some time; but this fact does not alter our determination of what is-the normal
behaviour of these plants. No other phenomena of regular alternation of
generations have been observed; I have seen indeed the mycelium formed from
gonidia produce zygospores first and then gonidiophores in Sporodinia grandis, the
species which most frequently produces zygospores and grows on fleshy Hyme-
nomycetes; but the reverse order of events is quite as common, and sometimes no
zygospores are formed at all. The mycelium developed from zygospores may in
this species produce zygospores directly, omitting the formation of gonidia?.

In all other known species the formation of zygospores is always preceded
by a copious development of gonidia on the same mycelium, and most specimens
never get further than the gonidia. It may be a question therefore whether possibly
a generation forming zygospores succeeds with some regularity to a large number
of successive generations which only form gonidia; experiments in artificial cultivation
have only given negative answers”.

Section XLII. The formation of zygospores is known only in the smaller
number of species, but these belong to almost all the chief genera of the group.
It begins in the case of each zygospore with the appearance of a pair of archicarps
(section XXXHII), and these are formed in Sporodinia on special erect dicho-
tomously branching hyphae resembling the sporangiophores; in all other known
cases they appear singly on sporangiophores (Chaetocladium, Absidia), or as im-
mediate branches of the mycelium spread in or on the substratum; the latter case
occurs also in Sporodinia, if the drawing in the vignette which precedes the tables in
Tulasne’s Carpologia is correct. The archicarps in each pair spring either from
spots in the hyphae which are morphologically close to one another, as in Phy-
comyces* and Sporodinia*, or from spots which are only locally adjoining, places
of contact of branches of morphologically remote origin, as in Piptocephalis® and
Mucor stolonifer‘. Both conditions of origin correspond to those which have been
described for the antheridia and oogonia of the Peronosporeae and Saprolegnieae,
and appear as in them to vary from species to species and in individuals of the same
species. The archicarps of a pair (Fig. 72 a, 5) are small branches of the hyphae,

1 Brefeld in Sitzgsber. d. Ges. naturf. Freunde z. Berlin, 15 Juli, 1875.
2 Brefeld, Schimmelpilze, IV.
3 Van Tieghem, I, t. 20, Fig. 4.
* De Bary, Beitr. 1.
5 Brefeld, Schimmelpilze, I, p. 48.
® De Bary, Beitr. II.
L 2

148 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

and are at first of the same breadth as the hyphae, and the even surfaces of their
extremities become firmly united together, in some species when their length is
not yet greater than their breadth, in others, it is said, not till a later stage of their
development. While thus attached to one another, and while dense oily proto-
plasm constantly. passes into them from the hyphae, they grow into bodies which
are broadly club-shaped towards the surface of attachment and straight or curved
according to the species; the two together therefore are spindle-shaped. When they
have reached a certain size, which in some species may be as much as 1 mm.,
the further development follows two different paths according to the species.

In the Mucoreae (Fig. 72) and the Chaetocladieae each archicarp is divided
by a transverse wall into a nearly cylindrical terminal cell, the conjugating-cell
or gamete which remains connected with the other of the pair, and into a larger
portion the swspensor (c), which adjoins the gamete and continues club-shaped
or conical. The two gametes are at first separated from one another by their
original membranes which form a tolerably thick partition-wall; but these are soon

e d
FIG. 72. Rrizopus nigricans, Ehr. (Mucor stolontfer, Ehr. Silv. myc.). Formation of a zygospore, Stages of

the develöpment according to the letters. e a nearly ripe zygospore magn. go times. The otfer figures reduced
to about tite proportion of e from larger drawings.

dissolved, the dissolution beginning from the centre, and thus the two protoplasmic
bodies conjugate and coalesce into a single zygospore d. After conjugation
the zygospore still increases in volume at the expense of the protoplasm of the
suspensors, swells into the shape of a barrel or of a ball with its, surfaces abutting on
the suspensors flattened, and assumes the characteristic structure which will be
described presently (Figs. 72 ¢, 71 C). During these proceedings the two gametes of
a pair behave in some species, as in Sporodinia, precisely alike, excepting inconstant
variations of form in individual plants. In other species tolerably constant dissimi-
larities make their appearance with the delimitation of the gametes. In Mucor
stolonifer (Fig. 72), where the point has been more exactly investigated, the one
gamete is almost always only half the height of the other; and after conjugation the
suspensor belonging to the smaller gamete grows into a large stalked spherical vesicle,
sometimes divided again by a transverse wall, while the other retains its original size
and conical form.

CHAPTER V.—COMPARATIVE REVIEW.—MUCORINI. 149

In the group of Piptocephalideae the archicarps are curved and so disposed
that the pair has very nearly the form of an Q or of an inverted M. The surface
of union lies in the apex of the bow (Figs. 73, 74 Z). In Syncephalis nodosa the
archicarps are coiled spirally round one another. Up to the time when the con-
jugation of the slender gametes is completed the development is essentially the
same as in the first-mentioned cases, but then the product of conjugation swells at
the place of coalescence into a spherical vesicle, which bulges on the convex side of
the bow of the N. Protoplasm passes into it in proportion as it increases in size.
When it has reached the limit of its growth, it is delimited by a partition-wall from
each limb of the bow and becomes a nearly spherical zygospore ; it may at least
be so called for the sake of clearness and simplicity, though it is plain that it is not
the strict morphological equivalent of the zygospore of the first case, but is a
daughter-cell of the zygospore, if the zygospore is the cell which results directly from
the conjugation of the pair of gametes. If we adopt the proposed terminology, the
spherical zygospore of Syncephalis
is placed at the apex of the bow
formed by the pair of suspensors,
and each suspensor is divided by a
transverse wall.

The behaviour of the zygospores,
while they are maturing, is essentially
the same in both cases, apart of course
from specific differences. The fatty
matter in the protoplasm, which con-
tinues to be dense and darkly granu-
lar, usually collects into several large
round drops. A further and exact )
insight into more delicate points of _Fıc.73. Piptocephatis Freseni jugation and formation of

. 5 zygospores, the —. in the order of the numbers. Z a ripe

structure in the protoplasm is scarcely ee a ee
attainable owing to its opaqueness.
The wall forms usually wart-like or conical projections on its free outer surface, in
Piptocephalis even before the delimitation of the zygospore, only those parts re-
maining smooth where it is in contact with the suspensors, and becomes differentiated
into a stout episporium the colour of which varies from brown to black, and a thick
stratified endosporium formed of more than one layer (Figs. 72 ¢, 71 C, 73 IE, 742).
The latter has either its outer surface quite smooth, as in Chaetocladium, and the
projections belong entirely to the episporium; or it is furnished with stout solid
projections which fit into corresponding depressions in the episporium (species of
Mucor, Sporodinia). Mortierella is the only exceptional case, in which the episporium
is not rough on its outer surface and owing to its close adherence to the investing
envelope is but little developed.

In many species, and in the majority of those which have been named above and
represented in Figs. 71-74, the ripe zygospore thus constituted lies naked and without
any further covering between the suspensors, which ultimately wither and decay.
But in some species an envelope is added to the parts already described in the
zygospore. Short branches shoot out in a simple or multiple circlet in the more

» 150 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

simple cases after conjugation from each suspensor near their line of junction with
the ripening zygospore; these branches, which have stout dark-coloured walls,
complete their growth as the zygospore ripens and form a loose envelope round it.
In Phycomyces! the branches of the envelope divide dichotomously and their
ramifications spread in every direction; in Absidia? they either do not branch again
or they have short tooth-like lateral branches, and bend crosier-wise from the two
suspensors over the zygospore. The formation of the envelope is more complicated
in Mortierella, in which the ripe zygospore is encapsuled by a number of layers
‘of compactly woven hyphae. The accounts which we possess show that the
development of the envelope varies in the different species. In M. nigrescens® the
hyphae of the enveloping tuft grow out at first after conjugation from the suspensors
and later also from the filaments bearing them, and enclose the zygospore as it
ripens in their copious ramifications. In M. Rostafinskii‘ the hyphae do not spring
from the suspensors, but only from the point of origin of the adjacent mycelial
hyphae, and envelope the conjugating pair with their branches before conjugation
is effected.

Azygospores. It happens not unfrequently in the Mucoreae that zygospores
which are otherwise normally developed contract a permanent constriction at the
place of coalescence, and the coalescence is therefore to outward appearance less
perfect than it usually is. But it may also happen that the gametes in a pair, after
being formed in the normal manner, do not coalesce, do not even come into contact
with one another, and the gametes may even make their appearance singly and not
in pairs (Absidia, Mucor tenuis), and yet have the normal structure of zygospores
and their normal capacity of germination. Spores thus formed and resembling
zygospores have been named azygospores. They are not produced in all species ;
they have not been found, for instance, after long continued search, in Mucor
stolonifer or in Chaetocladium ; they have been found in Absidia septata, A.
capillata®, Mucor fusiger®, and most frequently in Sporodinia, In this species they
are associated with the zygospores. Mucor tenuis according to Bainier only forms
azygospores, and perhaps Fries’ Azygites’, a plant which requires more precise
investigation, is also one of the Mucorini which have this peculiarity.

Zygospores or azygospores have up to the present time been described in Sporodinia
grandis ; Mucor Mucedo, M. racemosus, M. tenuis (Bainier), M. fusiger, M. stolonifer ;
Pilobolus (Pilaira) anomalus (Brefeld, Van Tieghem) ; Phycomyces nitens, Ph. micro-
sporus (V. Tieghem) ; Absidia capillata, A. septata (V. Tieghem) ; Mortierella 2 species
(vid. sup.) ; Choanephora 1 spec. ; Chaetocladium Jonesii and Ch. Fresenii (Brefeld) ;
Piptocephalis Freseniana (Br.) ; Syncephalis Cornu (V. Tieghem), S. nodosa, S. curvata
(Bainier) ; altogether 19 species, very few compared with the large number of existing
species. In many they may have been overlooked, being rare and concealed in the
substratum, and may yet be found. In others, as Pilobolus crystallinus, P. oedipus,
and Thamnidium elegans, they have been so often sought for in vain that it'may be
assumed that they never occur.

: Van Tieghem, I, t. 20. 5 Van Tieghem, III.
Id., II, t. 11. ® Id. II, p. 73.
3 Id. IIT. ? See Tulasne, Sel. Fung. Carpol. I, p. 64.

* Brefeld, Schimmelpilze, IV, t. V.

CHAPTER V.—COMPARATIVE REVIEW.—MUCORINI. 151

The species of the Mucorini which have zygospores, but no other organs of
propagation, have since Ehrenberg’s time! received the generic name of Syzygites.
Hildebrand? has described two such forms, one of which may belong to. Chaetocla-
dium, the other (Syzygites ampelinus) is of uncertain affinity.

Section XLIII. Typical gonidiophores. It has been already stated that the
spore when germinating normally produces gonidiophores as the first result of
development in the form of hyphae (simple sporophores) which are characteristic of
each species. Every strongly developed mycelium of the species produces similar goni-
diophores, which are at least the primary and often the only organs of propagation, if
we disregard the deviation from the usual course of development in Sporodinia, which
was mentioned above and scarcely requires to be considered. The species that are
thoroughly known, those, that is to say, in which zygospores have been observed,
have accordingly gonidiophores of a distinct form, which are shown by more than
one consideration to be constant and necessary members of the normal development
and also to be strictly homologous with one another, and it is these which are here desig-
nated typical gonidiophores. There are besides many species in which the zygo-
spores and their germination are not known, but which have gonidiophores agreeing
so entirely in all essential points with those of typical and thoroughly known species,
that they must be regarded as homologous with them and always have been so
regarded. These therefore come under the category which we are now considering.

The gonidia themselves, apart from the doubtful genus Zygochytrium, which may
be put aside for the present, are in all cases simple motionless comparatively thin-
walled spores, in other respects possessing the usual structure.

The genera and subdivisions of the group are chiefly distinguished as im the
Peronosporeae by the mode of their development, the structure of their sporangia,
and the structure and segmentation of their gonidiophores; to these are of course added
characters derived from the zygospores, mycelium, &c. The arrangement in the
following brief review of this group will be founded on these particulars. I go with
Van Tieghem in the definition and naming of the several genera, but merely for the
sake of brevity and convenience and without fully approving his minute divisions of
the forms; I differ from him as regards the primary division. Three primary
groups may be distinguished according to the manner of forming the gonidia or
spores :—

The Mucoreae ; spores formed endogenously in terminal sporangia by division
of the protoplasm into several or many portions (see section XVIII).

The Chaetocladieae ; spores abjointed acrogenously one by one (see section
XVI).

The Piptocephalideae; spores formed acrogenously and serially by cross-
septation (see section XVI).

1. MUCOREAE. The sporangia (Fig. 71 g, A) are nearly spherical, rarely club-
shaped terminal vesicles on the primary stalk or on the branches of the sporangiophore.
In Mortierella they are placed with a narrow insertion on the slender extremity of
the branch that bears them, and are delimited in the plane of insertion by a horizontal

‘ Verhandl. d. Ges. naturf. Freunde zu Berlin, I, p. 98.
2 Jahrb, f. wiss. Bot. VI, p. 270.

152 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

basal transverse wall ; their wall, except at the plane of insertion and the parts imme-
diately adjoining, deliquesce in water when it is mature. In the other genera (Fig. 71)
the basal wall of all or of the larger sporangia expands into a conical dome-like or
ellipsoid form and projects into the cavity of the spotangium, and from its shape is
termed the columella. Among these genera is Pilobolus: its sporangium thick-walled
with a basal expanding layer (p. 83), solitary terminal on an unbranched turgescent
vesicular sporangiophore, from which it is abjected when ripe or (Pilaira, V. Tieghem) re-
moved by swelling.—Mucor : outer wall of sporangium deliquescing when mature, usually
incrusted on the outside with short spreading needles of calcium oxalate ; sporangio-
phore narrow filiform, with or without single branches arising monopodially (Phy-
comyces, Spinellus = Mucor fusiger but differing from Mucor in the formation of the
zygospores, Sporodinia differing in its dichotomous sporangiophores and suspensors).
The sporangia in the genera Rhizopus, Circinella, and Absidia have the same
structure as in Mucor, but the filiform sporangiophores branch sympodially. In
Rhizopus and especially Rh. nigricans (= Mucor stolonifer) the sporangiophores rise
like stolons from the mycelium, ascending at first in a curve and then letting their
points drop downwards. In this way they may reach a length of from one to several
centimetres. If their apex touches a firm substratum, the previous growth in length
ceases, and a number of incipient branches make their appearance behind the
apex. Some of these branches develope with the apex of the stolon itself into shortly-
branched rhizoids closely appressed to the substratum; others, usually from three
to five in number, raise themselves above the substratum and become rigid branchlets
2-3 mm. in height, each of which terminates in a sporangium ; lastly, one or a few
of them develope as stolons which may repeat the same course of development’.
Absidia has according to Van Tieghem a similar mode of growth to Rhizopus, but
with the difference that the stolons of the successive orders describe very regular
curves, and that a tuft of sporangiferous branches spring above from the convexity
of the curve. On the erect sympodial sporangiophores of Circinella see Van Tieghem,
as cited in end of section XLIV. While the above genera have sporangia of only one
kind, those which constitute the Thamnidium group have two kinds: large ones
quite like those of Mucor, and terminal like them on the primary stem of the sporan-
giophore which is monopodially branched or not branched at all; and small ones,
sporangiola, usually formed on the extremities of the many ramifications of lateral
branches of the sporangiophore which ends itself in a large sporangium. In all the
species of this group sporangiophores occur which only produce one large sporan-
gium, and others which produce only sporangiola. The sporangiola are distinguished
from the sporangia not only by their small size and the reduction of the number of
their spores to 2 or 1, but also by their level or slightly convex basal wall, which does
not rise high into a columella, and the comparatively thick smooth outer wall without
incrustations, which persists till after the ripening of the spores and is in many cases
only burst by their germination. There is no difference in the germination of the two
kinds of spores or in their products. Van Tieghem distinguishes the genera Thamni-
dium, Chaetostylum, and Helicostylum by the shape and ramification of the branch-
lets that bear the sporangiola.

2. CHAETOCLADIEAE. The genus Chaetocladium which forms this division
contains two species very like one another, which are usually parasitic on the larger
Mucoreae in the manner described in section V. The filiform erect gonidiophores
produced from the zygospore usually terminate in a slender subulate hair-point,
beneath which they form a whorl of usually 2-5 short branches standing out at a
right angle, which again branch and form further whorls of a second or third order.
The branching axes which become shorter with each successive order end each in its

1 On deviations from this rule of growth see de Bary, Beitr. II, and Wortmann in Bot. Ztg.
1881, p. 368,

CHAPTER V.—COMPARATIVE REVIEW.—MUCORINI. 153

turn in a hair-point ; the lateral branches of the last order swell into irregularly capitate
basidia, from the short slender sterigmata of which 8-20 spherical spores are
simultaneously abjointed. Similar sporiferous structures with hair-points are formed on
the terminal ramifications of copiously branched gonidiophores, which rise in a curve
into the air from well-fed mycelia in a similar manner to the stolons of Rhizopus.
Many variations occur in the number and disposition of the whorls and the successive
orders of branches; a small cluster of spores may take the place of the terminal
hair-points, especially in weakly specimens. It is hardly possible to detect any strict
tule in the primary branching of the stolons, the typical form of which appears to be
indiscriminately sympodial and monopodial. Some of the primary branches terminate
in spore-clusters; others seize on
sporangiophores of Mucorandadhere
to them, and send out new stolons
from the points of adherence which
are swollen. Zygospores also are
formed on the stolons. Cunning-
ham’s Choanephora may also be-
long to this division, with a creeping
endophytic mycelium and straight
erect simple sporophores ending in
umbellately arranged heads of ba-
sidia, from which many spores are
simultaneously abjointed.

3. PIPTOCEPHALIDEAE. In Syn-
cephalis the very delicate mycelium
gives rise to short erect unicellular
usually unbranched gonidiophores
with a circle of rhizoids at their base,
and with one bifurcation in S. furcata.
A dense umbel of simple or dicho-
tomously branching spore-rows is
formed at the capitate swollen apex
of the gonidiophore by the cross-sep-
tation of cylindrical mother-cells (see
section XVI). Piptocephalis (Fig.
74) differs from Syncephalis in its re-
peatedly dichotomouslybranchedand
septate simple sporophores which
are often large and tall, and in the
circumstance that the capitate sum-
mit which bears the spore-rows falls
off with them when they are ripe.
The mycelium of the species of both Wee ee a er ees
genera 1s par asitic on the larger to M and sending slender filaments into it, ¢ gonidiophore, Z zygo-
Mucoreae, making its way into their aa ee Loe ig ee ns
cells by means of delicate haustoria
(section V).

The formation of the gonidia of Chaetocladium and the Piptocephalideae was
described and named above in section XVI in accordance with the facts observed
in Chaetocladium, Piptocephalis Freseniana, and Syncephalis. Van Tieghem’s view
of the process is different from mine. He considers that the spore-chain of Synce-
phalis and Piptocephalis is formed, like the gonidia of Mucor, simply by division of the
protoplasm of the mother-cell, and is then set at liberty by the disappearance (resorp-
tion) of its membrane ; and he regards the acrogenously formed spores of Chaetocladium

154 DIVISION II—COURSE OF DEVELOPMENT OF FUNGI,

as monosporous sporangia completely filled by the spore, and most comparable with the
sporangiola of the Thamnidieae. These interpretations, which are not in accordance
with the facts, have evidently arisen from a perception of the truth, that all the gonidial
formations in question are homologous, coupled with the erroneous notion that
homologous spores must necessarily originate by exactly the same mode of cell-
formation. We naturally gain nothing more from such interpretations in this case
than in others of older date which were noticed above on page 116. The homologies
are brought out quite simply in our case, as has been shown above, without these
artificial helps; and conversely the case before us shows with special distinctness that
members and cells may be homologous, though all the facts observed with regard to
them do not belong exactly to one and the same category of the scheme of cell-
formation which is accepted at the time.

Section XLIV. Aceessory gonidia. In a number of species, in Sporo-
dinia grandis for example, Brefeld’s Mucor Mucedo, Rhizopus nigricans and
Chaetocladium, the cycle of forms is exhausted by the appearance of the members
which have now been described; but in other species gonidial formations occur
in addition to the typical ones, some of which by their form and structure are
eminently characteristic of species and genera. It would seem that they are always
found on starved or old mycelia, but the conditions of their formation have not been
in every case clearly ascertained. It would be difficult to find any other general
name for them than the one here chosen. Many of them have been called by Van
Tieghem chlamydospores and stylospores, others gemmae, &c. It will be most
convenient to choose a suitable name for each case as it presents itself.

Characteristic accessory gonidia are the acrogonidia of Mortierella and some
species of Syncephalis. They are solitary and acrogenously abjointed on the
summit of slender cylindrical branchlets of the mycelium, and are spherical in
shape and usually of considerable size in Mortierella (as much as 20 » or more
in diameter), but small in Syncephalis (6 »); they have a thick episporium with
its surface marked with warts or spikes in a manner characteristic of the different
species, and they emit germ-tubes which may develope into the normal mycelium.
They are formed in Mortierella on erect branches of the mycelium which are either
isolated or are united into small umbels; in the species of Syncephalis from short
stalks which are arranged in dense racemes springing at right angles from a fusiform
swollen portion of a mycelial filament. A very remarkable instance of the formation
of accessory gonidia is that described by Cunningham in his genus Choanephora,
in which the heads of basidia mentioned above must, from the mode of their
occurrence on the normally developed mycelium, be certainly regarded as the typical
gonidiophores, though the germination of the zygospores has not yet been observed,
and cannot therefore confirm this view. But erect simple sporophores make their
appearance on old and starved mycelia by the side of meagre heads of basidia, and
form at their summit a spherical mucor-sporangium having a warted outer wall, a
slightly convex basal wall, and containing a number of ellipsoid smooth-walled
spores, which can germinate and produce a normal mycelium.

Another form of accessory gonidia is known under the name of gemmae or
brood-cells. Their ordinary mode of production is that short pieces of a mycelial
tube or gonidiophore, which is rich in protoplasm, become delimited by transverse
walls to form cylindrical or nearly spherical or ovoid or pear-shaped or similarly

CHAPTER V.—COMPARATIVE REVIEW.—MUCORINI. 155

shaped cells, which often acquire thick membranes and then under favourable
conditions of vegetation and in many cases after a long resting period develope
into normal mycelial tubes. These cells are densely filled during their resting
period with tolerably homogeneous protoplasm; but sometimes, and especially
in starved or dying or dead specimens, numerous large drops of oil may become
separated in the protoplasm, a circumstance which once gave occasion to some
passing misapprehensions?. On old mycelia especially, and in species of Mucor on
sporangiophores also, the protoplasm of which is usually employed in forming gonidia
of other kinds, these gemmae occur frequently as cylindrico-ellipsoid cells inserted like
stoppers at irregular intervals in hyphae which are otherwise without protoplasm?.
They occur frequently in many species, especially in those of Mucor; in some,
as Chaetocladium, Piptocephalis, and Phycomyces, they have not yet been observed.
In old cultures of Pilobolus they make their appearance on the slender branches of
the mycelium especially, and not unfrequently in thick swellings in them, which
if vegetation is continued develope into typical sporangiophores; they resemble in fact
incipient sporangiophores which have remained stationary at the first stage of their
development and have become dormant, and have a thick yellowish brown outer mem-
brane and dense reddish yellow protoplasm; they are liable to be mistaken for zygo-
spores, and grow when they germinate into typical gonidiophores. The smooth-walled
‘chlamydospores’ of Mortierella, described by Van Tieghem, also belong to this
class. Those which are not intercalary but terminal in the mycelial hyphae are
obviously transition-forms to the acrogonidia mentioned above.

Under certain conditions of vegetation some of the Mucoreae also form
gemmae, which may be distinguished from the preceding by the names of chazn-
gemmae and sprout-gemmae. ‘These forms have been most thoroughly studied
in Mucor racemosus and have been described by Brefeld?, but they occur also,
according to Van Tieghem, in other and very different species. The formation
of these gemmae begins when the mycelium is submerged in a nutrient fluid,
especially in a saccharine solution capable of alcoholic fermentation, and is thus
cut off from the free access of oxygen. Numerous transverse walls divide the
entire mycelial tubes into short segments, which may be narrowed into mere disks
and are swollen with protoplasm. The segments may, as Berkeley* said in 1838,
remain united together in a confervoid manner or separate from one another, and, if
the conditions remain the same, they often sprout luxuriantly after the manner of the
Sprouting Fungi described on p. 4. If spores are submitted to the same conditions,
they first swell into large spherical vesicles and then sprout directly without first
forming germ-tubes. The sprouts which proceed from them have almost, if not quite
always, the form of spherical vesicles which grow to more than 40 a in diameter and
repeatedly put forth new generations of sprouts by copious development at all parts
of their surface; the new sprouts either continue united together or some of them
separate from one another. This sprouting form of Mucor was formerly known as

1 See Bot. Ztg. 1868, p. 765.

? Bail in Flora, 1857, t. XIII.—Zabel in Melanges biolog. Acad. de St. Pétersbourg, III.—
Brefeld in Thiel’s Landw. Jahrb. V (1876), p. 282, t.1. See also the works cited below passim.

3 Landw. Jahrb. V (1876).—Id. in Flora, 1873.

* Mag. of Zoology and Botany, II, p. 340.

156 DIVISION II.—-COURSE OF DEVELOPMENT OF FUNGI.

“sphere-yeast” or ‘ mucor-yeast,’ partly from its resemblance in shape to the Saccharo-
mycete of yeast and partly from its power of exciting alcoholic fermentation. Under
certain conditions the sprouts behave like spores of Mucor.

All the gemmae which have now been described are capable of developing by
germination into normal mucor-mycelium, either at once or after a prolonged period
of rest, if properly fed and supplied with air. Each gemma of Mucor racemosus,
cultivated in moist air without supply of food, is capable of developing at the expense
of its protoplasm into a typical but very minute sporangiophore with a sporangium
containing in extreme cases not more than eight spores (Brefeld).

Doubtful Mucorini. 1. Sorokin! has described under the name of Zygochy-
trium aurantiacum a Fungus which grows on dead insects beneath the water, and
which if that writer’s observations are confirmed is asmall species of this group adapted to
growing in water. The entire plant consists of an erect tube with two bifurcations, alto-
gether scarcely o.1 mm. in height, attached to the substratum by short lobes at its base
without any proper mycelium. Globular sporangia producing numerous swarm-spores
with one cilium as in the Chytridieae (see section XLVI) are formed at the extremities of
the branches; and a zygospore is also produced at the first bifurcation in perfect specimens
in the manner which has been described in the case of Mucor. The course of
development is in other points like that of Mucor. These observations have yet
to be confirmed.

2. Van Tieghem® describes under the names of Dimargaris cristalligena and ,
Dispira cornuta two Fungi growing on dung, which have very peculiar gonidiophores,
but otherwise agree with Piptocephalis in being parasitic on the Mucorini, in the
mode in which they enter the cells of their host, in the presence of transverse walls in
the gonidiophores and in the chains of gonidia. The genesis of the gonidial chains is
not indeed fully described, but the drawings would seem to show that it is similar to
that of Piptocephalis. It is as yet by no means certain that these Fungi belong to the
Piptocephalic group, but this affinity is highly probable, since we know of na species
outside the Mucorini which they approach in form. The point can only be decided by
the discovery of zygospores or some structure homologous with them.

3. The same may be said of a small group, which may be called the Coemansieae,
consisting of Coemans’ Kickxella and Martensella and Coemansia of Van Tieghem
and Le Monnier. The mode of life of these Fungi, of Kickxella at least and Coemansia,
is the same according to Van Tieghem as in Piptocephalis. In the structure of their
gonidiophores, the only part at present known beside the mycelium, they differ materially
from the acknowledged members of the group of the Mucorini. Their common and
chief peculiarity consists in the possession of basidial branches of somewhat fusiform
appearance, falcately curved, and divided by transverse walls into several cells from which
on the concave side of the branch numerous spores, placed clase together in two or more
comb-like longitudinal rows, are abjointed both simultaneously and one by one. The
spores themselves are narrowly fusiform, pointed at both ends, and emit their germ-tubes
at right angles to their own longitudinal axis. Basidial branches of this kind form in
Kickxella a whorl of 6-14 members with their concave sides upwards on the apex of the
erect septate filament that bears them, which is elsewhere usually unbranched and is
scarcely 0.3 mm. in height. In the other genera they stand singly in racemose
arrangement on the dichotomously ramifying branches of the gonidiophore. No
zygospores are known; but Coemans and afterwards Van Tieghem and Le Monnier
found small ascomycetous sporocarps in the neighbourhood of the gonidiophores ;
whether they belonged to each other is a very doubtful question.

1 Bot. Ztg. 1874, p. 305. ? Van Tieghem, II.

CHAPTER V.—COMPARATIVE REVIEW.—MUCORINI. 157

Historical Remarks. The course of development in the Mucorini was first
observed throughout by myself in my examination of Sporodinia or Syzygites mega-
locarpus carried out in 1860 and published in a complete form in 1864, and next
by Tulasne in 1867 in Mucor fusiger, after he had already shown in 1855 that the
fungal forms designated by the generic names above given are parts of the same
species. Schacht’s observations on Sporodinia! were published at the same time as my
own and not before them, and his results agreed with mine. For the further enlarge-
ment of our knowledge of this rich group we are indebted mainly to Brefeld and Van
Tieghem. In the work? which I brought out in conjunction with Woronin in 1865 I
gave a fresh account of the development of Rhizopus nigricans, but it was imperfect, as
it did not contain the full history of the germination of the zygospores ; and some
confusion was caused in the same work by our introducing Chaetocladium, a parasite
on Mucor, into the cycle of forms of Mucor Mucedo on the evidence of cultures, which,
through my fault not Woronin’s, were not perfectly regulated. It is not true indeed
that Thamnidium elegans was also introduced into the same cycle, but it would be no
serious fault if it had been, because it can form gonidiophores without sporangiola which
are then scarcely to be distinguished from those of Mucor Mucedo, and the separation
or non-separation of two species nearest to one another is almost without effect on
the determination of the course of development of the Mucoreae. Then Brefeld at
my instigation undertook a revision of ‘the apparently irregular pleomorphy’ of the
collective supposed Mucor Mucedo and succeeded in making out the true state of the
matter. Van Tieghem and Le Monnier confirmed and added first to our incorrect, and
then to Brefeld’s correct results.

Other views on the course of development in the Mucorini differing from those
given above, especially the idea of a genetic connection between Mucor and Saccha-
romyces, which will be noticed again in section LXXVIII, belong to the history of the
pleomorphy craze (page 126). The special literature already cited and to be cited below
contains references to it. The reader is referred to the same source for an account of
the strange controversy maintained at an earlier time on the subject of the structure of
the sporangifim of Mucor. In the case of a group so much discussed as the Mucorini
we can only give the main sources of information, in which some further and more
particular references on points of detail will be found.

Literature of the Mucorini.

DE BARY and WORONIN, Beiträge, I and II.

TULASNE, Note sur les phénoménes de Copulation, &c. (Ann. d. sc. nat. sér. 5, VI,
1867).

O. BREFELD, Bot. Unters. ii. Schimmelpilze, I and IV.

P. VAN TIEGHEM et G. LE MONNIER, Recherches sur les Mucorinées (Ann. d. sc. nat.
sér. 5, XVII, 1873); cited in the text as Van Tieghem, I ;—Id., Nouvelles Recher-
ches sur les Mucorinées (Ann. d. sc. nat. sér. 6, I, 1875); cited in the text as Van
Tieghem, II ;—Id., Troisitme mémoire sur les Mucorinées in Ann. d. sc. nat. ser.
6, IV (1878) ; cited in the text as Van Tieghem, III.

G. FRESENIUS, Beitr. z. Mycologie, I (1850), III (1863).

E. CoEMANS, Spicilége mycologique No. 3, in Bull. Soc. Bot. Belg. I (Kickxella) ;—Id.,
Quelques Hyphomycétes nouveaux (Mortierella, Martensella), in Bull. Acad. roy.
de Belgique, ser. 2, XV ;—Id., Recherches sur le polymorphisme et les différents
appareils de reproduction chez les Mucorinées, I et II (Bull. Acad. roy. de Belgique,
XVI) ;—Id., Monographie du genre Pilobolus (Mém. couronné de l’Acad. roy. d.
Belg. XXX).

1 Sitzungsber. d. Niederth. Ges. z. Bonn, 7 Apr. 1864.
2 Beitr. II.

158 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

H. HOFFMANN, Icones analyt. Fungor. IV, 1865 (Mucor, Rhizopus).

ZIMMERMANN, Das Genus Mucor, Chemnitz, 1871.

J. KLEIN, Zur Kenntn. d. Pilobolus (Pringsheim, Jahrb. VIII, p. 305).

A. GILKINET, Mémoire sur le polymorphisme des Champignons (Mém. couronné de
l’Acad. roy. de Belg. XXVI, 1878).

O. BREFELD, Ueber Gährung, III, in Landw. Jahrb. ed. Thiel. V, 1876 (Mucor
racemosus).

D. D. CUNNINGHAM, On the occurrence of conidial fructification in the Mucorini,
illustrated by Choanephora (Linn. Soc. Trans. London, ser. 2, I, 1878).

BAINIER, Observations sur les Mucorindes et sur les zygospores des Mucorinees (Ann.
d. sc. nat. ser. 6, XV, 1883). First brought to my notice while this work was
being printed.

ENTOMOPHTHOREAE.

Section XLV. We proceed to give a brief account of this small group to which
we may apply the terminology in use for the Mucorini; the Fungi which supply the
material for our description penetrate into the cavities of the bodies of living insects
and there develope, forming their gonidiophores on hyphal branches, which make
their way through the body of the insect after its death and complete their
development on its outer surface.

In a certain number of species, as Empusa Muscae and E. macrospora, Now.,
numerous detached and at first spherical cells are formed by repeated sprouting from
. the germ-tube which has penetrated through the skin into the interior cavities
of the insect, and each cell developes as the insect dies into a long tube containing
much protoplasm. In other species, as Entomophthora radicans, E. ovispora
and E. curvispora, the germ-tube in the insect’s body produces a mycelium composed
of copiously branched hyphae, divided by transverse walls and often connected
together by anastomosing branches. In most instances the Fungus forms its gonidia
on the surface and after the death of the insect. In the Empusae one extremity
of each separate tube pierces the insect’s skin, grows outside it into a short cylindrico-
club-shaped body, and then forms acrogenously a single spore, which is abjected by
the mechanism described on page 72. The protoplasm and other contents of the tube
are expended for these purposes, and the tube itself then perishes. In the Ento-
mophthoreae numerous branches of the entozoic mycelium appear on the surface of
the body of the dead insect and there ramify in so copious a manner that they soon
wrap it in a close felt. Much the largest part of this felt consists of branches
set very nearly at a right angle to the surface of the body, and their last ramifications,
which end at about the same level and form a compact hymenium, are cylindrical in
shape and unicellular, and ultimately one spore is abjointed and flung off in the
manner just described. Hyphae and tufts of hyphae also appear before the sporo-
genous hymenium at certain spots on the ventral side of the dead insect, especially
on caterpillars attacked by Entomophthora radicans, and develope into rhizoids
which secure the body to the substance on which it lies. In both cases the whole
of the protoplasm of the Fungus is expended in forming the spores; as they are
produced one after another on the extremities of the tube or its branches, these
shrink in size and with them the body which they occupy; at last there remains only

CHAPTER V.—COMPARATIVE REVIEW.—ENTOMOPHTHOREAE. 159

a shrivelled drying mummy, surrounded by a circle of spores or gonidia which have
been thrown off. The latter are capable of immediate germination, and do germinate
if duly supplied with moisture, either emitting a germ-tube which penetrates at once
into the body of a suitable insect and goes through the process of development above
described, or only producing short tubes from the extremity of each of which a new
secondary gonidium with the same qualities as the primary is abjointed. The
gonidia soon lose the power of germination; in Empusa Muscae, for example, it does
not continue beyond about fourteen days.

The Fungi are limited to the above course of development in most of the insects
which they attack. In some cases, however, few or no gonidia are formed and
zygospores OT azygospores are ultimately developed, and in most species inside the
body of the insect. Nowakowski gives the following description of the formation
of zygospores in Entomophthora ovispora and E. curvispora. The cells of adjacent
hyphae develope an H-shaped union by means of the necessary processes, and
establish an open communication at the point where the processes are in contact with
one another. Then a spherical protuberance makes its appearance near the
point of union, either on the cross-bar of the H or close to it, and receiving
as it grows the entire protoplasm of the conjugated pair of cells is finally delimited
by a membrane, and becomes.a zygospore in the sense in which the word is used in
the case of Piptocephalis.

No azygospores have been observed in these species. But Entomophthora
radicans and the species of Empusa examined by Nowakowski have only azygospores
which are produced without conjugation as lateral outgrowths on the mycelial tubes
or acrogenously like the gonidia, as in the species named by Nowakowski Lamia
culicis. It would appear therefore that there is a difference in the matter of con-
jugation in the different species similar to that which is found in the Saprolegnieae
as regards the presence or absence of the antheridial branches. Both zygospores
and azygospores become resting spores in the same way. The membrane
becomes much thickened and is differentiated into a thick usually bright yellow
episporium with a smooth surface in most species, and a thinner endosporium, while
a large, globular, nearly central drop of oil separates in the protoplasm from
the general finely granular turbid mass. The mycelium is dissolved and disappears
after the formation of the resting-spores, which are therefore the only remains of the
plant in the mummified body of the insect. Their germination was observed
by Nowakowski in Empusa Grylli, and consists in the emission of a short tube, the
promycelium, which forms a gonidium at its apex; the gonidium is abjected, in the
same way as gonidia from the gonidiophores described above.

The above account is a summary of Brefeld’s and Nowakowski’s observations. The

differences in the statements of the two writers with regard to conjugation are to be
explained by the different behaviour of different species. The genetic connection once
frequently assumed between the Entomophthoreae and other Fungi, especially Saccharo-
mycetes and Saprolegnieae, is a subject for the history of botanical errors. Information
on the point will be found in the works cited below.
_ Cohn has described as Tarichium a species which preys on ground-caterpillars ; it
has only resting-spores with thick walls roughened on the outside with warts, and may
perhaps belong to this section. In Nowakowski’s opinion both the development and
affinity require to be more closely examined.

160 DIVISION 11.—COURSE OF DEVELOPMENT OF FUNGI.

The Entomophthoreae do not live exclusively on insects. Completoria complens,
which according to Leitgeb’s observations is one of the group, is a small parasitic Fungus
in the cells of the prothallia of ferns. Leitgeb’s account of its structure, of the formation
of its gonidia on the extremities of branches which have emerged from the cells of its
host, and of its resting-spores, agrees almost exactly with these features in Empusa and
Entomophthora. Brefeld also! has recently reported an allied species, which he found
parasitic on some Tremellineae, and names Conidiobolus utriculosus.

Literature of the Entomophthoreae.

F. CoHN, Empusa Muscae und d. Krankheit d. Stubenfliegen (N. Act. Acad. Leop.
XXV, pars ], 1855).

S. LEBERT, Die Pilzkrankheit d. Fliegen (Verh. d. Naturf. Ges. z. Zürich, 1856).
G. FRESENIUS, U. d. Pilzgattung Entomophthora (Abh. d. Senkenb. Ges. II, 1858).

O. BREFELD, Unters. u. d. Entw. d. Empusa Muscae u. E. radicans (Abh. d. Naturf.
Ges. z. Halle, XII, 1873).

F. COHN, Ueber eine neue Pilzkrankheit d. Erdraupen (Beitr. z. Biolog. d. Pflanzen, I,
1874, P- 58).

L. NowakowsKI, Die Copulation einiger Entomophthoreen (Bot. Ztg. 1877, p. 217).

BREFELD, Schimmelpilze, IV (1873), p. 97 ;—Id., Hefepilze, 1. c.

H. LEITGEB, Completoria complens, ein in Farnprothallien schmarotzender Pilz
(Sitzungsber. d. Wiener Acad. 84, Abth. ı, 1881).

M. SOROKIN, Zwei neue Entomophthora-Arten in Cohn’s Beitr. z. Biol. II, Heft 3.

A. GIARD, Deux espéces d’Entomophthora, &c. (Bull. sc. du départ. du Nord, ser. 2,
année 2, No. I1, p. 253).

L. NowAakowskI, Entomophthoreae (Abh. d. Acad. d. Wiss. z. Krakau, 1882, (Polish).
Report on the same in Bot. Ztg. 1882, p. 560.

CHYTRIDIBAE.

Section XLVI. This is the name for what has gradually become a very varied
series of small microscopic forms, which spend their entire vegetative period, or at
least a definite stage of their spore-producing time under the water, and agree
morphologically in forming swarm-spores in sporangial cells of a fixed and. definite
shape; each swarm-spore has usually one cilium, and developes either directly or
through inconspicuous transition states into fresh sporangial cells. Resting-spores
are also known in certain species, and these develope directly in germination into
sporangia or produce them after a short intermediate stage. There is such great
similarity in the formation of sporangia and swarm-spores, that the species composing
the group have always, one may almost say instinctively, been considered to be closely
related to one another. Yet our knowledge of the several species is so unequal, and
the course of development in the best-known forms is so different in extreme cases,
and these extremes are so imperfectly connected by the intermediate forms with which
we are acquainted, that we must at present feel in doubt whether we are dealing in
this case with a series of objects naturally related to one another, or with a number of
groups of similar adaptation and therefore of similar form, but of different natural

1 Hefepilze, p. 10.

CHÄPTER V.—COMPARATIVE REVIE W.—CHYTRIDIEAE. 161

though close affinities. With this reservation we will first proceed to describe the
points of form which are common to them all. See the Figs. 75-77 below.

The sporangia are cells of varying shape and diameter in the different species,
and are often furnished with one or more wart-like or neck-like processes, which
finally discharge the spores from their swollen and projecting apex, or which, as in
Chytridium Olla, are cast off like a lid for the same purpose. They are furnished
when fully grown with a moderately thick wall of cellulose, and densely filled with a
uniformly finely-granular fatty protoplasm, which at length divides simultaneously into
numerous spores. In most species the division is preceded by separation of the pro-
toplasm-granules, which are colourless or coloured yellow, orange, or rose, according
to the species, into as many groups divided by narrow hyaline streaks, in each of which
the granules then coalesce to form bodies of successively larger size, and ultimately a
single sphere consisting chiefly of fatty matter. This sphere of fatty matter then lies,
usually excentrically, in the body of the swarm-cell, which otherwise consists of
hyaline protoplasm and allows a nucleus to be seen in the larger forms’. Such a
swarm-cell when set at liberty is roundish or elongated in shape, and is furnished
with one cilium which is several times longer than the diameter of the body, The
sphere of fatty matter is much more frequently, but not always, brought near the point
of insertion of the cilium; exceptions to this structure occur in most of the species
only as monstrosities. But in some there is no fatty sphere (Chytridium macrosporum,
Ch. roseum, &c.). The spores of Olpidiopsis Saprolegniae, Woronina, and Rozella
have according to A. Fischer always two cilia.

The spores are discharged from the sporangia by the process of swelling
described in section XX, and in some species are at first held together in a mass
by mucilage, from which they are afterwards gradually set free one after another;
in other species they leave the cavity of the sporangium one by one. Where the
dimensions and the speed of their movements allow of exact observation, the cilium
is usually seen to follow the body in the process ofrelease from the sporangium. The
movement in the water is described as being clearly in many species a hopping
movement; a progression by hops in no strictly determinate direction alternates
in longer or shorter periods with a state of quiescence and each hop is associated
with a stroke of the cilium like the stroke of a whip. But this kind of movement is
not found in all the species. The spores of Nowakowski’s Chytridium Mastigotrichis
and the highly phototactic spores of Polyphagus Euglenae and of Strasburger’s
Chytridium vorax move forward with moderate speed and uniform rotation round
their longitudinal axis and with the extremity that has no cilium in front, while the
cilium follows passively behind. The time that the movement continues varies in
each case, being seldom more than an hour, often much less; in a few cases, as
in Synchytrium Taraxaci, it is considerably more. Towards the end of the period
of movement an undulating change in the outline of the body often takes the
place .of the phenomena which have been described, together with an amoeboid
creeping on a firm substratum, in which the cilium is dragged behind.

The resting-cells or resting-spores of the Chytridieae are on an average nearly or
quite as large as the sporangia, and are distinguished from them by thick, often

? See above, pp. 107-109.

[+] M

162 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

very thick, and many-layered membranes, the outer layers of which, the epi-
sporium, are coloured and sclerosed in many species, in some are furnished with
wart-like or slender spike-like prominences; they may also be known by their very
dense protoplasm containing a large quantity of fatty matter uniformly distributed in
small drops or granules, as in species of Synchytrium, or aggregated into a few drops
or into one comparatively large round drop, as in Polyphagus, Chytridium Brassicae,
Wor., Rhizidium mycophilum, A. Br., Chytridium Olla. The resting-spores remain
dormant for some time before germinating.

If we next endeavour to form an idea of the course of development in the
Chytridieae, we shall find that our present knowledge permits of our distinguishing
four types, which might perhaps be combined by pairs into two main types. Each
of these has one or more chief representatives, and each of these again has a crowd
of imperfectly known forms doubtfully associated with it. There are no distinctly
intermediate forms between the two types.

FIG. 78. Polyphagus Euglenae. A swarm-spore with sphere of fatty matter and nucleus. B young plant grown from a
swarm-spore with a branch of the rhizoid attached toa resting Fug ec ii with formation of spores just

completed and resting on the empty mother-vesicle 2 (prosporangium) from which it has proceeded ; on the vesicle are three

'hizoid-b ‘h D ji ion; @ the ptive individual, 4 the supplying indivi $ the swollen end of the tube of
conjugation connecting @ and 4, which end is becoming the rudiment of the resting spore, ee the Exgl/enae attacked by the
Polyphagi, E a portion of the pair shown in D 54 hours later than D; & and s indicate the same parts as in D, 6 empty, s
mature. After Nowakowski. .4 magn. 550, B, D, E 350, C about 4oo times,

Section XLVII. 1. Rhizidieae. One species belonging to this section,
Polyphagus Euglenae, a parasite upon resting Euglena viridis, has become the
best-known of the Chytridieae through Nowakowski’s beautiful investigations (Fig.
45). The swarm-spore when it has come to rest in the water becomes spherical
in shape, and at once puts out hair-like tubular-rhizoid processes in indefinite
directions (2). If one of these encounters a resting Euglena (e), it penetrates into its
body, destroying and exhausting it to supply food to the parasite. The parasite
then begins to increase in size, the rhizoid-tubes become larger and thicker, and
mew ones are formed which throw out branches, and attack and destroy any new

CHAPTER V.—COMPARATIVE REVIEW.—CHYTRIDIEAE. 163

Euglenae which they encounter. In this way a much-branched plant is formed with
hair-like terminal branchlets, which connect with the larger main stems and through
these with the body of the original spore; the latter has grown in the meantime into
a large round or elongated vesicle at the expense of the Euglenae, which have been
exhausted by the rhizoids. When it has reached a certain size, varying according to
the food which has been supplied to it, it shows itself in many specimens to be a
sporangium, or, if the term is preferred, a prosporangium. It grows out at one spot
into a bluntly and irregularly cylindrical thick tube with a delicate membrane, into
which the whole of the protoplasm passes, and is at once divided into swarm-spores
(Fig. 75 C). This process of development may be repeated for many generations, and
leads to an immense multiplication of individuals if there is a sufficient number of
Euglenae within reach. When this has taken place, the course of events changes.
The young plants remain for the most part small and become gamefes, which con-
jugate in pairs, each pair forming a zygospore, and these behave as resting-spores.
The two conjugating gametes of a pair (Fig. 75 D) have no definite position or
distance with respect to one another, and are similar in form to the non-conjugating
plants. The one (4), which from the processes to be described may be termed the
supplying gamete (abgebende Gamete), has usually a round and larger body, but shows
no other apparent difference before contact with the other (a), the recepfive gamete
(aufnehmende Gamete). The latter usually continues to be smaller, and often very
small, and puts out rhizoid branches, and if one of these, after longer or shorter
growth, encounters a supplying gamete it applies its extremity to it as a conju-
gating tube (s) and increases in thickness while it ceases to increase in length.
The membrane between the conjugating tube and the supplying gamete disappears
at the point of attachment, and an open communication between them being thus
established, the whole of the united protoplasm of both gametes passes into an
enlargement of the conjugation-tube close to the point of attachment; the swelling
gradually expands into a spherical vesicle, and being delimited by a membrane after
receiving the protoplasm becomes a thick-walled zygospore (Z, s). The outer wall
of the zygospore assumes a pale yellow colour, and in some cases continues smooth,
in others is covered with short spikes, which begin to form at the same time as the
enlargement in the tube. The whole process of forming. a zygospore from the
attachment of the conjugating tube to the maturation of the zygospore was com-
pleted, in the case observed by Nowakowski, in about 6-7 hours.

A few instances are known of the conjugation of 2-3 receptive with one supplying
gamete and of the consequent formation of 2-3 zygospores. The zygospore, as has
- been already said, is a resting-spore. It germinates when its resting time is over and
produces a zoosporangium like the non-conjugating plants.

Polyphagus therefore is essentially characterised by the gametes with their
rhizoids, the mode of forming the zygospores, and the production of the zoo-
sporangium or of swarm-cells from it. It may be assumed to be possible for these
swarm-cells to develope directly into gametes; but an indefinite number of generations
of non-conjugating plants are in fact interposed between two successive gamete-
generations. The gametes in each pair behave differently in conjugation, as has
been shown, and the species is dioecious. Which of the two should be called the
male and which the female is not easy to determine, and must not be further discussed

M 2

164 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

in this place. It is evident that we have before us an intermediate case between the
ordinary forms of oogamous and isogamous conjugation.

Besides a second species of Polyphagus, exactly like P. Euglenae, which attacks
Conferva bombycina and is called by Nowakowski P. parasiticus, there are a number
of Chytridieae which affear to belong to the type of P. Euglenae. Among the first of
these, according to Schréter’s brief communication (1882), is Physoderma pulposum,
Wallr., a plant endophytic in the Chenopodiaceae, and with some highly peculiar
characters about which we await fuller information. Another in all probability is
Rhizidium mycophilum which inhabits Chaetophora elegans, and, according to
Nowakowski’s account, and putting aside some variations in form which we may at
present disregard, is entirely like Polyphagus Euglenae in all important points of
structure and development ; we do not indeed know the formation of the resting-spores,
but their germination is the same as in Polyphagus. Then there are a number of
forms described under the names Rhizidium and Rhizophydium (with Obelidium
of Nowakowski), most of them parasitic on larger Algae, in which as in Polyphagus the
body of the germinating swarm-spore puts out rhizoids and grows into a swarm-
sporangium, and in which mature resting-spores of unknown origin have been found here
and there. These Rhizophydieae also, from the account which we have of them, require
further examination. Finally we may class with those already mentioned a number of
A. Braun’s typical Euchytridieae and Phlyctidieae which live in Algae, since they
resemble them in structure, and their rhizoids were overlooked by the older observers on
account of their great delicacy. How far this is the true view of their affinity must be
determined by further research, which, if I am not misled by imperfect observations,
requires to be extended even to the most typical Euchytridieae such as Chytridium
Olla.

I add what follows in justification of this remark. Chytridium Olla, A. Br., is parasitic,
as Braun tells us, on the unripe oospores of Oedogonium rivulare and kills them. Its
swarm-spores settle according to Kny’s description on the orifice of the oogonium which
is filled with mucilage, put out slender rhizoid-processes from thence towards the
oospore suspended in the oogonium, and then convert their body which is outside the
oogonium into a sporangium ; the rhizoid-process becomes a thick cylindrical stalk by
means of which the sporangium is attached to the oospore, and which is delimited from
the sporangium by a transverse wall when the development is complete. I am inclined to
doubt whether the rhizoid-process or stalk of the sporangium proceeds from the cilium of
the swarm;spore, as Kny states, because this is never the case in other species of similar
growth, though there is often the appearance of it; I have never examined into this
point in Chytridium Olla. The swarm-sporangium is ovoid in shape when fully grown,
and when it discharges its spores it throws off the apical portion of its membrane like a
small lid, as is shown in Fig. 76 A, B. According to the reports of observers the stalk
is attached firmly to the surface of the oospore by its obtuse extremity only; but when
attempting to detach it I often saw the extremity prolonged into a little point which seemed
to pierce through the membrane of the-oospore, but could not be followed into its interior.
My material was very old when I undertook the investigation, and the sporangia
of the parasites on the oogonia were already emptied of their contents, and it was
quite possible that rhizoid-processes might have penetrated into the oospore at an
earlier stage but have disappeared in the decomposed contents of the oospore at the
time of the investigation.

In older cultivated plants of Oedogonium which have been attacked by Chytri-
dium Olla we often find a great many oospores of the Alga, which were killed by
the parasite while still young and when their walls were still thin, and inside them
in their decomposed cell-contents colourless glistening round bodies usually in large
numbers. These when carefully examined (Fig. 76 A) and isolated (C) prove to be
thick-walled spherical cells containing a dense strongly refringent central sphere of

CHAPTER V.—COMPARATIVE REVIEW.—CHYTRIDIEAE. I 65

fatty matter in a finely granular protoplasm tightly packed in a vesicular receptacle,
which was evidently an intercalary member of a very slender branch filament. The
spherical cells rich in fatty matter are resting-spores of Chytridium. Aftera long resting
period (about four months in the cases which have been observed) they germinate and
put forth a cylindrical germ-tube, which as it grows takes the shortest way to reach the
outside, piercing through the membranes of the oospore and the oogonium. When its
extremity has reached the outer surface of the oogonium, it swells into an ovoid spo-
rangium, which resembles in every respect that which is ascribed to Chytridium Olla.
It is developed at the expense of the protoplasm of the resting-spore, which passes
through the germ-tube into the sporangium after the dissolution of the fatty sphere ; before
this transference has come to an end a transverse wall makes its appearance in about
the middle of the tube, and the sporangium when fully grown is also delimited from
the tube by a transverse wall (Fig. 76 A, B).

So much is matter of observation. The gaps in our knowledge of the details are
readily descried ; speaking in general terms we may say that the question of conjugation
and fertilisation is still unsettled, and that the continuity of the development between the
germinating swarm-spore and
the filaments which form the
resting-spores has not been satis-
factorily established. This latter
defect would be of very small
importance in presence of the
perfect similarity between the
sporangia developed from the
swarm-spores of Ch. Olla and
those from the resting-spores, if
another form, also a Rhizidium,
had not been observed in the
plants examined under cultiva-
tion, which at least resembles
Chytridium Olla in the formation
of the sporangia. The sporangia
of this species are not as like
the sporangia developed from withan killed by the parasite; the

e resting-spores of Chytridium which ripened in October; ‘three of these spores
the resting-spores as are those areseen still d, two have germinated. By turning the specimen round

it was seen distinctly that the empty sporangium @ was formed from the rest-
of Ch. Olla, but they always Te- ing-spore 2’, and the sporangium 4, which is ejecting its contents, from 5;

semble them enough to make it near the mouth of d are the cast-off lid and two zoospores. 3 an isolated
rae resting-spore after ination with the i still undivided, from
necessary to be careful in inter- another speci C resting-spore in a 1 hed to the b
2 of the filament on which it was formed, prepared from a dead oospore like that
preting the observed facts. shown ind. A, B magn. 475, C oxo times,
In conclusion we refer once

more in this place to the genus Zygochytrium mentioned on p. 156.

FIG. 76. Chytridium Olla, A. Br. (). A oogonium of Oedogontum rivulare

Section XLVIII. 2. Cladochytrieae. A delicate much-branched and widely
spreading mycelium resembling the rhizoids of the Rhizidieae forms numerous
terminal and intercalary sporangia on its branches, and the germinating swarm-spores
give rise to a mycelium resembling the original one. The sporangia of many species
are only known in the form of resting-spores.

The species first determined by Nowakowski in this group inhabit the decaying
tissues of marsh-plants and the jelly of Chaetophora. The course described above
has been directly observed in them from the germination of the swarm-spores to the
production of the next sporangiferous generation. The sporangia are formed in large
numbers on the vegetating mycelium and proceed to form their spores at once without
passing through a period of rest.

166 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

A second series of forms are intracellular parasites in the living and otherwise sound
foliage of some of the marsh plants infested by the first mentioned group. They form
brown spots or pustules on the leaves, and spread from cell to cell, and often produce a
large number of sporangia in each cell without coming out to the surface of the plant.
To this group belongs the form which has been described as Protomyces Menyanthis,
and another which may be named provisionally Cladochytrium Iridis. All the
sporangia in these two species are converted, as the mycelium disappears, into thick-
walled often brown ellipsoid resting-spores (Fig. 77), which, as far as is known, germinate
only after hybernation and then form swarm-spores. This was observed by Goebel, as he
informed me by word of mouth, in Cladochytrium Menyanthis, and by myself in C. Iridis.
The germination of the swarm-spores has not yet been observed.

The occurrence of members of both these groups in the tissue of the same plant, as
for example in Iris Pseudacorus, might lead to the supposition that the forms of the first
group belong to the same species as those of the second which form resting-cells ; but
there is no fact to show this, and it is opposed to the observation that a large number
of swarm-spores of Cladochytrium Iridis will not germinate even on dead tissue of Iris
Pseudacorus. They seem to require living cells for their further development, but
I could not see that they made their way into them.

No act of conjugation and no sexual organs
have been observed in these plants. In the
formation of intercalary sporangia and resting-
cells it is often observed, that an intercalary
swelling of a branch of the mycelium first
appears and is then divided by a transverse wall
into two halves; one of these halves swells into
a sporangium, while the other does not enlarge
and loses its protoplasm. But it cannot be
seen that the protoplasm has passed over, as
might be supposed, into the half which is in-
creasing in size, it seems on the contrary to

Fic. 77. Cladochytrium Iridis. a a resting-spore travel into the growing mycelium ; and on the
with a brown membrane seen from the broadside. dthe other hand the whole of the p art that swells at

same rotated through 90°; in its centre a large sphere

of fatty matter. c—es ivestagesof germinationof first often becomes a sporangium or resting-cell
a resting-spore ; the inner cell developes into a tubular A a oe.
swarm-spore-receptacle, when the brown outer membrane without previous transverse division. The con-
has opened by a lid. @ completion of the formation of = ed : :

the spores. e exit of the spores. /asingle swarm-sporc. Jugation of the Swarm-spores, which might also

ae magn. 375, 7'500 times, be expected from analogy, has not been ob-
served.

The forms of Physoderma, Ph. maculare, Wallr. inhabiting Alisma graminifolium,
Ph. Heleocharidis, Fuckel, Schröter’s (1882), Ph. Butomi and Ph. vagans, the latter of
which is found in different Phanerogams (Potentilla anserina, Ranunculus flammula,
&c.), are very like Cladochytrium Menyanthis and C. Iridis as regards the intracellular
development and the structure of their resting-spores in the inner layers of the
parenchyma of the leaves oftheir host. But these species according to Schröter have
no mycelium; the single resting-spore is formed in the same way as in Synchytrium.
We are not told how their primordia find their way into the interior of the cells.

Section XLIX. 3. Olpidieae. We are indebted to A. Fischer for a com-
plete account of the development of Olpidiopsis Saprolegniae and O. fusiformis,
Cornu. The former plant causes a pouch-like swelling in the tubes of the
Saprolegnieae which it inhabits, and in its full-grown state is an ellipsoid or round
cell which forms neither rhizoids nor mycelium, but ultimately becomes a sporangium
and discharges its zoospores through one or more cylindrical necks which pierce

’

CHAPTER V.—COMPARATIVE REVIEW.—-CHYTRIDIEAE. 1 67

through the wall of the tube of the Saprolegnia. Each sporangium is the product of a
swarm-spore which forces its way into the interior of the tube of the young Saprolegnia,
and there lives in amoeboid form in and at the expense of the protoplasm of the tube,
and finally after 3-5 days’ time is invested with a membrane and becomes a
sporangium. The sporangia appear in two forms ; either they are smooth-walled and
as soon as their growth is completed produce swarm-cells or else die and disappear ;
or they have the surface of their membrane beset with delicate spikes and form
swarm-cells at once from their dense protoplasm, or first spend a period of at least
several weeks’ duration as resting-cells, and then produce swarm-cells. The spores
of both kinds of sporangia are alike in origin and structure. But the spores
formed in the smooth-walled sporangia generally develope into spiky sporangia, and
those in the spiky sporangia into smooth ones; if the conditions are unfavourable
to vegetation spiky sporangia are produced in greater numbers than the smooth.
Every smooth and every spiky sporangium is formed, as has just been said, directly
from a single swarm-spore. Former statements or conjectures to the contrary have
not been confirmed by direct and more complete observation. Olpidiopsis fusiformis,
which lives in species of Achlya, agrees with O. Saprolegnieae according to A. Fischer
in all the details of its history.

We may consider not only the other parasites of the Saprolegnieae which were
placed by Cornu in the genus Olpidiopsis, but A. Braun’s Olpidieae also and other
forms that are without rhizoids, to be nearly related to those which have just been
described; their affinity is shown by the facts observed, especially the entire absence
of rhizoids on the sporangia and the accompanying phenomenon of the resting-cells
with spiky membranes. It is not at all easy to see why Cornu separates Olpidiopsis
from Olpidium; but this group of species is imperfectly known and needs further
investigation.

Section L. 4. The group of Synchitrieae is marked by the entire absence
of rhizoids and by the circumstance that an zzztial cell proceeding from one swarm-
spore breaks up by simultaneous division into a heap (sorus) of polyhedric sporan-
gial cells which produce swarm-spores. The number of sporangia in a sorus varies
from two to more than a hundred.

The typical forms of this group are gall-forming parasites which live in the
epidermal cells of phianerogamous land-plants, where they produce swollen vesicles ;
the sporangia which ripen or the resting-cells which germinate if supplied with water
burst the membrane which encloses them in order to release the spores or sori,
if these have not been previously set at liberty by the decay of their investment.

Two subordinate groups may be distinguished according to their special course of
development, Eusynchytrium and Pycnochytrium, the latter embracing Schröter’s
Chrysochytrium and Leucochytrium. Pycnochytrium hasthe simpler development. The
swarm-spores which have made their way into the young cells of their host are converted
into very large thick-walled resting-cells, one usually in each cell. The resting-spores
remain dormant for some time, usually for about a year, and then germinate in the
manner shown in Fig. 78; the colourless endosporium emerges through a small orifice
in the layers of the episporium in the form of a slender papilla, which then slowly
developes into a spherical vesicle on the outer surface of the episporium and receives
the whole of the fatty protoplasm of the resting-cell (a-c). While the protoplasm

168 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

is gradually becoming finely granular, it divides into the numerous sporangia which
form the sorus (c,d). The swarm-cells (g) discharged from the sporangia become new
resting-cells, if they find a host. This is the history, for example, of Synchytrium
Mercurialis, S. Anemones, &c. ‘The course of development in the Eusynchytrieae
is somewhat different; an unlimited number of generations of sori may be and
actually are interpolated between every two successive hybernating generations
of resting-cells; these sori are formed from swarm-spores without there being
any resting period and produce again new swarm-spores. The spore which has
penetrated into the swelling cell of its host developes into the thin-walled initial cell,
which divides into the members of the sorus as soon as it has reached a definite stage
of development. After a number of such generations have been produced, partly
perhaps owing to external causes, the formation of resting-cells recommences. The
behaviour in germination of these also varies in different species; in some, as for
instance Synchytrium Stellariae (Fig. 78) and S. Oenotherae, they form sori like
those of the Pycnochytrieae; in others each resting-cell becomes a single sporangium
directly without forming sori, as in S. Taraxaci.

FIG. 78. Synchytrium Stellariac, Schrot., from Stellarıa media, a—d germination of the resting-cells when placed
in water after hybernating in the dry state. a—c successive states of the same specimen, 4 four-hours later than @, c seven days
later and 'five days after division into the cells of thesorus. da mature sorus with the mature sporangia falling asunder. e—g a
single iumin water. ei diately after being taken from the sorus. J the same two hours later shortly before formation
of spores, the small sphere of fatty substance being divided into parts of equal size. g forty-five minutes later with the swarm-
cells escaping. a—d magn. 145, e—g 375 times.

It is obvious that the difference between the Synchytrieae and the group of the
Olpidieae lies in the formation of sori. Species like Synchytrium Taraxaci with
resting-cells which become sporangia without dividing are to some extent intermediate
forms. Neither conjugation nor any sexual process has been observed in either group.
From the facts before us we can only gather that a sorus or resting-cell proceeds
directly from a swarm-spore. Influenced by the analogy of the isogamous Algae and
Protomyces, I sought carefully in Synchytrium Stellariae and S. aureum for the con-
jugation of free swarm-cells, but, as was the case in my examination of Cladochytrium,
I never found an instance of it, either between spores of one or of different sporangia’
belonging to the same or to different sori. The abnormally large swarm-cells which
are observed occasionally with two or more spheres of fatty matter and additional
cilia are monstrous forms and not products of conjugation. These negative results
do not preclude the possibility of conjugation; it might occur inside the cell of the
host if more than one swarm-cell had found its way there. Cornu is inclined to
account in this way for the formation of the resting-cells of Synchytrium, but he
adduces no decisive observations in support of his view, but only an arbitrary com-
parison of states of S. Stellariae found side by side. The objections to this are
so obvious that they need not be specified. Direct observation of the development

CHAPTER V.—COMPARATIVE REVIEW.—CHYTRIDIEAE. 1 69

is in this case indispensable ; it is not easy to manage but still it is not impossible.
Observation should be directed also to the origin of the initial cells of the sori as well as
to that of the resting-cells, for there is no apparent reason why the latter should arise
without and the former with conjugation. It should also be extended to more than one
species, for the oogonia and antheridia of the Saprolegnieae show that what is the rule
in one species is not so necessarily in another. If we were prepared to draw arguments
for the formation of sori by conjugation from isolated facts, we might find them in the one
which was first observed by Schröter, that there is a broad empty brownish-looking
membrane adhering to one side of every full-grown sorus in Synchytrium Stellariae and
S. Succisae inside the swollen cell of the host. Schréter, however, gives a different
and probably the true explanation of this circumstance; he supposes that .a vesicle
which takes up the protoplasm issues out of the original membrane of the initial cell
shortly before the formation of the sorus, as in the germination of the resting-cells of
Pycnochytrium, but this has not however been directly observed.

The course of development in the genera Woronina and Rozella, Cornu, is very like
that of the Synchytrieae ; in outward appearance, as parasites of the Saprolegnieae,
they are certainly sufficiently unlike the Synchytrieae which inhabit Phanerogams.
A. Fischer’s complete investigations have distinctly proved the absence of conjugation
and sexuality in these genera; for a detailed account of them the reader is referred
to Cornu and A. Fischer. Their very peculiar mode of life will be noticed in
Division III.

Section LI. If we compare the facts of development in these four groups with
those in other Fungi, we see that the chief points of connection with the latter are to be
found in the first group. Polyphagus may at once be put side by side with the Mucorini
as a very small form adapted to a submerged life by the formation of swarm-spores ;
the connection is still more perfectly effected by Zygochytrium, which ranks with
the Mucorini as truly as with Polyphagus, if Sorokin’s statements are confirmed (see
page 156). The homologies are sufficiently brought out by the terminology employed.
There are also obvious points of connection with the Ancylisteae (page 139). Of the
other groups the Cladochytrieae come nearest to the Rhizidieae, even if sexual pro-
cesses are really wanting in them and are not merely undiscovered. It is possible
that some of the Rhizidieae themselves may be in the same condition. With a similar
supposition necessary at present, we may regard the two other groups as nearly
related to the Rhizidieae, if we consider them to be forms in which the formation
of rhizoids or mycelia has fallen into disuse, or been entirely lost, in consequence
of special and intimate parasitic adaptation; the Olpidieae will then come nearest to
the Rhizidieae, and there is no difficulty in connecting. the Synchytrieae with
the Olpidieae. In this view of the subject the whole division of the Chytridieae
would be regarded as a lateral branch either of the Mucorini or of the Ancylisteae,
which has been gradually simplified in correspondence with its submerged parasitic
life and has reached its most specialised condition, in which it differs most from
the preceding divisions in Woronina and Rozella, genera of the Synchytrieae.

On the other hand the resemblance of the simple Chytridieae without rhizoids
to unicellular Algae, especially the Protococcaceae, Characium, Chlorochytrium, &c.',
has always been recognised. The question of course arises whether this resemblance
is the expression of close phylogenetic affinity, or only of analogous adaptations; for
‘apart from the presence of chlorophyll, the conjugation of swarm-cells which prevails

1 See Klebs in Bot. Ztg. 1881, p. 249.

170 DIVISION II,—COURSE OF DEVELOPMENT OF FUNGI.

among these algal forms is a fact which separates them at present from the
Chytridieae. At the same time the first view is not one which can be entirely set
aside ; we are not sure, as has been said already, that phenomena do not occur in the
Chytridieae which are at least very near akin to the conjugation of swarm-cells,
namely, the supposed conjugation of the young plants just formed from swarm-cells,
which have made their way into cells of the host. But if the simple Chytridieae are
really related to the Protococcaceae and form a natural series of affinities with all the
rest, this series linking with the Protococcaceae must also extend to Polyphagus
and the Ancylisteae and Mucorini.

At the foundation of all such considerations lies the supposition, that the four
different groups of the Chytridieae really form a genetic series. This supposition
is usual and admissible, but is not necessary. There may quite as well be two
or even more than two series before us of separate affinities connected together
by certain similarities of adaptation; on one side the Olpidieae and Synchytrieae
without mycelia, and on the other side the Rhizidieae with Cladochytrium; the latter
would unite with the Mucorini or Ancylisteae and could be derived phylogenetically
from them ; the former would come from other forms, for instance the Protococcaceae.
These questions and considerations cannot lead at present to any certain decision,
they can only point out the direction for further enquiries.

Section LII. Doubtful Chytridieae. 1. Along with the above-mentioned Zy-
gochytrium Sorokin’ describes a Tetrachytrium triceps, which forms four swarm-
cells in each sporangium ; the swarm-cells conjugate in pairs after their escape from
the sporangium, then round themselves off and germinate. Before conjugation they
resemble those of the Chytridieae. Those which have not conjugated are incapable
of germination. Germination gives rise to a small sporangiferous plant, which is
attached by a short rhizoid-process to the substratum (vegetable substances decaying
in water), and consists of a tube-like cell with four branches formed by bifurcation,
three of which terminate in a sporangium and the fourth is sterile, having the form
of a horn-like process.

2. The same observer”. found on submerged rotten wood in Venice a plant,
Haplocystis mirabilis, consisting of a pear-shaped cell, about 110 » in diameter, the
protoplasm of which divides by successive bipartitions into 32 parts; the parts round
themselves off, and conjugate in pairs after rotating inside the mother-cell. Then the
cell opens by a lid and the products of conjugation issue from it in the form of swarm-
cells provided with two cilia; these cells come to rest in about a quarter of an hour and
develope into a cell like the mother-cell. These two remarkable accounts have still
to be confirmed. If they are correct, we have to do with organisms which can
scarcely belong to the Chytridieae, but must be related to the Protococcaceae.

There are other and probably many forms of similar habit to the Chytridieae,
some of which are very imperfectly known, while others would seem to be certainly
distinct from the Chytridieae, but not referable at present to any other group. We
cannot go further into the subject of these forms in this place; reference to
some accounts of them will be found in Schenk, Algol. Mittheilungen (Amoebidium
parasiticum, see below), and Cienkowski, Bot. Ztg. 1861, p. 169.

1 Bot. Ztg. 1874, p. 308. 2 According to Just’s Jahresbericht, 1875, p. 190.

CHAPTER V.—COMPARATIVE REVIEW.—PROTOMFCES. 171

Literature of the Chytridieae :—
A. BRAUN, Ueber Chytridium, eine Gattung einzelliger Schmarotzergewächse (Monats-
ber. d. Berlin. Acad. Juni, 1855, and Abhandl. derselb. Acad. 1855, p. 21, tt. 1-5) ;—

Id., Ueber einige neue Arten v. Chytridium u.d. damit verwandte Gattung Rhizidium
(Monatsber. d. Berlin. Acad. ı Dec. 1856).

F. COHN, Ueber Chytridium (Nov. Act. Leop. Car. 24, I, p. 142).
BalIL, Chytridium Euglenae, Ch. Hydrodictyi (Bot. Ztg. 1855, p. 678).
CIENKOWSKI, Rhizidium Confervae glomeratae (Bot. Ztg. 1857, p. 233).

A. SCHENK, Algol. Mitth. (Verhandl. d. Phys. Med. Ges. z. Würzburg, Bd. VIII) ;—

Id., Ueber d. Vorkommen contractiler Zellen im Pflanzenreiche, Würzburg, 1858
(Rhizophydium).

DE BARY u. WoRONIN, Beitr. z. Kenntn. d. Chytridieen in Ber. d. naturf. Ges. zu
Freiburg, III (1863) and Ann. d. sc. nat. ser. 5, III (Synchytrium).

DE Bary, Beitr. z. Morph. u. Phys. d. Pilze, I, in Abhandl. d. Senkenb. Ges. Frank-
furt, 1864 (Cladochytrium Menyanthis).

Woronin, Entwicklungsgesch. v. Synchytrium Mercurialis (Bot. Ztg. 1868, p. 81) ;—Id.,
Chytridium Brassicae (Pringsheim’s Jahrb. Bd. XI, 1878, p. 557).

Kny, Entwicklung v. Chytridium Olla (Sitzungsber. d. Berliner Naturf. Freunde).
See also Bot. Ztg. 1871, p. 870.

M. Cornu, Chytridinées parasites des Saprolegniées in Ann. d. sc. nat. ser. 5, XV
(1872), p. 112 (Olpidiopsis, Rozella, Woronina, &c.).

J. SCHROTER, Die Pflanzenparasiten aus d. Gattung Synchytrium (Cohn’s Beitr. z.
Biol. I, 1, 1875) ;—Id., Ueber Physoderma (Berichte d. Schlesischen Ges. 1882).

L. NowAKOWSKI, Beitr. .. Kenntn. d. Chytridiaceen in Cohn’s Beitr. z. Biol. II (1876),
p- 73 (Chytridium, Obelidium, Rhizidium, Cladochytrium) ;—Id., Polyphagus
Euglenae (Cohn’s Beitr. z. Biol. II, p. 201) ;—Id., Ueber Polyphagus, in Polish (Abh.
d. Krakauer Acad. 1878).

A. FISCHER, Ueber d. Stachelkugeln in Saprolegniaschläuchen (Olpidiopsis) in Bot.
Ztg. 1880) ;—Id.. Unters. ii. d. Parasiten d. Saprolegnieen (Habilitationsschrift,
Berlin, 1882, and Pringsheim’s Jahrb. Bd. XIV).

PROTOMYCES AND THE USTILAGINEAE.

Section LIII. Protomyces macrosporus (Fig. 79) is a parasite which lives
in the intercellular spaces of umbelliferous plants, especially Aegopodium; it has a
branching filiform mycelium with transverse segmentation, which produces numerous
intercalary resting-spores and then dies. The resting-spores, which may be more
than 60 p» in diameter, are irregularly ellipsoid in shape, filled with dense fatty proto-
plasm and provided with a very thick many-layered cellulose-membrane. They
germinate after hybernation in water when set free by the decay of the umbellifer. In
germination the endosporium with the protoplasm which has become finely granular
swells into a spherical vesicle, bursts the thick layers of the episporium, and issuing from
it becomesasporangium. A large number of rod-like spores only about 2.2 u in length
are formed in a sporangium in the manner described in section XIX and are ejected
from it; they are thin-walled and without independent movement, but show slight
oscillations caused by currents in the water; they are thus brought into close proximity
with one another if this has not happened directly by ejection, and conjugate in pairs
by means of slender processes usually in the form of the letter H. Scarcely anything

172 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

but pairs thus united are to be seen in a few hours after ejection; the two halves
of each pair are in open communication, and in most cases also swollen to a
larger than their original size. Each of these double spores is capable of germinating
under conditions which will be described in section XCVI; one of the halves
puts forth a tube which takes the whole of the protoplasm of the pair, and pene-
trating into a suitable host developes there at once into a new mycelium, which
forms resting-spores. No further stage of the development is known.

The plant in question with its peculiar and simple course of development is at
present an isolated form; only the resting-spores are at present known of a second
species, Protomyces pachydermus, Thiimen’, which grows on the Cichoraceae and has
probably a similar history.

Section LIV. The Ustilagineae are endophytic parasites in phanerogamous
plants. Their mycelium, which usually spreads through the intercellular spaces
of the host, consists of slender hyphae with comparatively long segments. In
some species it has haustorial branches each with a tuft of sinuous branchlets

Z d

FIG. Protomyces macrosporus, Unger. a a mature resting-spore in the dormant state with | the remains of the hypha which
bears it. 2 further development of the same when grown in waters the pr ic body sur d by the i
layer (the inner cell) is swelling and escaping from the rup d outer b layer. c—e devel of spores in the escaped

inner cell, the sporangium. c the parietal protoplasm. @ the same divided into spores. Ine the spores are rounded off and separated
from the remainder of the parietal protoplasmic layer. Magn. 390 times.

which penetrate into the cells of the host (see page 20). Resting-spores or
more shortly spores, are formed in or on the host, either, as in Entyloma, in all
parts of the mycelial hyphae, or in special branches different from those first
formed. These sporogenous branches of the Fungus form very numerous ramifica-
tions, and are usually woven together in great numbers into compact masses of definite
shape and occupying definite spots; they are generally found inside the plants attacked
by the Fungus, especially in the flowers and fruit or in parts of them that are
diseased and swollen, and there they in great measure destroy and consume the
tissue; less often (for instance Sorosporium Saponariae, Ustilago Tragopogonis,
U. hypodytes) on the surface of the part attacked which they closely cover up.
We may therefore in these cases speak of spore-producing bodies, compound
sporophores, in the sense of section XII. The Entylomeae, on the other hand, are
simple hyphomycetous forms, and other species, those especially which live in
leaves (species of Tilletia and Urocystis), are intermediate between the two extremes.

! Hedwigia, 1874 and 1878, p. 124.

CHAPTER V.—COMPARATIVE REVIEW.—USTILAGINEAE. 173

It is true that most of these compound sporophores have no independent
form of their own, for they merely fill cavities in the substance of the host, though
these cavities owe their existence and particular shape to the Fungus; or they
are flat layers something like a Thelephora covering superficial portions of the
plant. Yet the growth of many of these bodies evidently follows a single common
plan; it is continued for a time at fixed spots by the constant formation of fresh
sporogenous branches which form a weft—in the superficial layers, for example, on
the whole of their basal surface,—and on removal from these spots comes to an end
or passes on to formation and maturation of spores.

Most of these bodies consist only of sporogenous hyphae which are gradually
used up to form spores, so that heaps of spores only remain at maturity. But there
are species whose compound sporophores form other organs as well, which accom-
pany or envelope the spores. Rudimentary forms of this kind are perhaps to be
seen in the pellucid vesicles which Meyen discovered between the spores of Ustilago
longissima and which require to be further investigated, also in part at least in
the filaments in the spore-masses of U. olivacea which are still unexplained. Cornu’s
Doassansia, one of the Ustilagineae which is parasitic on water-plants and approaches
Entyloma in the structure and germination of its spores, forms its spores inside
a round closed receptacle, the wall of which consists of compact palisade-cells
belonging to the Fungus. Ustilago Hydropiperis has a much and distinctly differ-
entiated spore-receptacle, and might on that account be made a separate genus
under the name of Sphacelotheca. But the greatest amount of differentiation in
the compound sporophore is to be seen, according to Ed. Fischer’s researches, in the
genus Graphiola, if it should prove really to belong to the Ustilagineae.

We have said enough to show that the compound sporophores of the Ustilagineae
deserve more attention than has been bestowed upon them since Tulasne’s first memoir.
Cornu’s examination of Doassansia is only known to me from a preliminary and private
communication from the author, but a more detailed account of it is to be expected
shortly. The reader is referred to Ed. Fischer’s own paper for his investigation of
Graphiola ; and we may proceed to give a description of Sphacelotheca, the parasite of
the flowers of Polygonum Hydropiper mentioned above, as an example of a highly
differentiated compound sporophore, though the investigations of the year 1854, from
which we must draw our material, are old and in same points defective (Fig. 80).

Sphacelotheca forms its compound sporophore in the ovule of its host. When
the ovule is normally and fully developed in the young flower, the parasite, which
always grows through the flower-stalk into the place of insertion of the ovary, sends its
hyphae from the funiculus into the ovule, where they rise higher and higher and
surround and penetrate its tissue to such an extent as almost entirely to supplant
it, and thus an ovoid Fungus-body of densely interwoven hyphae takes the place of the
ovule. The micropylar end of the integuments alone escapes the change, and remains
as aconical tip (Fig. 80 C, 0) on the apex of the Fungus-body and gradually turns brown
and dries up. The Fungus-body is at first colourless and uniformly composed of much-
branched hyphae, which are woven together into a compact mass and have the gelatinous
walls of the simple sporophore of Ustilago to be described below. If it has retained its
ovoid form as it steadily increased in volume, differentiation begins first in the apical region

_into a comparatively thick outer wall which is closed all round, an axile columnar
cylindrical or club-shaped body, the columella, both parts remaining colourless, and a
dense sdore-mass which fills the space between the two and becomes of a dark violet
colour (Fig. 80 C, D). The lower part which corresponds to the funiculus and chalaza

174 DIVISION II,—COURSE OF DEVELOPMENT OF FUNGI.
of the ovuleremains undifferentiated, and an abundant formation of new hyphae is
constantly taking place in it. This new formation is so added from below to the
differentiated portion, that the latter constantly increases in height without becoming
materially broader, and maintains therefore the form of a cylinder pointed at the upper
end. Where the parts below approach the wall, columella, and spore-mass, they assume
their structure and colour. In other words, each of the three portions grows from its
base by addition of new tissue-elements, which are constantly being produced and
pushed onwards from a basal formative tissue, and are differentiated and assume their
ultimate form in the order in which they are produced (Fig. 8° C and D). The
development and mature structure of the spore-mass are the same as those of Ustilago,
which will be described presently. The
wall in its fully developed state is a thick
coat formed of many irregular layers of
small round cells not very firmly united
together. These cells are formed in the
same way as the spores from the hyphae
of the primary tissue, and are of about the
same size as the spores with a delicate
colourless membrane, and for the most
part with watery hyaline contents. The
columella has the structure of the wall,
but it usually incloses in its tissue evident
brownish fragments of the tissue of the
ovule, and consists at its uppermost ex-
tremity of much larger, firmer hyaline
cells, the origin of which I am unable
to explain. I may also observe that the
upper extremityin youngspecimens always
ends blindly in the spore-mass (C), but
in some older ones reaches to the apical
portion of the wall and passes into it (D);
it is still uncertain whether this is a dif-
ference in the individual plants or a
difference of age.

The spore-receptacle which has now
been described is formed only from the
ovule. The perianth and stamens of the

FIG. 80. Spacelotheca Hydroptperis in the flower of Polygonum
Hydropiper. A ripe compound sporophore of the Fungus pro-
jecting from the perianth of Polygonum. B the same with the
mass of spores emerging from the sporophore. C median longi-
tudinal section through a young fructification and its environ-
mhent, D longitudinal section through an older sporophore, c the
columella, # the perianth, /the wall of the ovary, o the integument
(mycropyle) of the ovule, g the style. In C and D the sterile
or young tissue of the Fungus is shaded by longitudinal lines, the
mass of ripening spores is darker. Further explanation in the
text. Slightly magnified.

flower continue in their normal state.
The wall of the ovary and the style are
also not attacked by the Fungus; they
do not follow the growth of the spore-
receptacle, and as this advances the
lateral wall is distended and at length
bursts transversely ; the style with the

upper portion of the wall dries up into a
small point at the apex of the receptacle, which is borne by the latter as it grows out of
the perianth (4). The wall of the spore-receptacle, especially where it is covered above
by the withered remains of the wall of the ovary, is very fragile and tears asunder at
the slightest touch to discharge the spores (2).

Section LV. Thedevelopment of the resting-spores commences in Entyloma
(Fig. 81 a), as in Protomyces, with intercalary abjunction at any spot in the hyphae ;
in Tilletia the resting-spores are terminal, being formed singly from the extremities of
branches of sporogenous hyphae. In Geminella Delastrina they originate by serial

CHAPTER V.—COMPARATIVE REVIEW.—USTILAGINEAE. 175

abjunction ; all the sporogenous hyphae divide, according to Winter, by transverse walls
arising from the extremities of their curved terminal branches in basipetal succession
into short members, which develope into spores united together in pairs.

The development of the spores of Ustilago may be briefly described in about
the same words, only in this case the ripe spore-cells are.not united in couples,
but are isolated and free. The terminal ramifications of the sporogenous hyphae
are in some species (U. Ischaemi according to Winter, U. hypodytes according to
my old account) slender and filiform, but they are usually furnished with many
tufts of short branches, so that they have a peculiar clustered and lobed appearance
(Fig. 82). Ustilago has the further peculiarity that the membranes of the hyphae
swell strongly into a jelly synchronously with or even before the basipetal segmentation
by cross walls into short isodiametric members, which also takes place in them. The
protoplasm of each individual member is therefore soon surrounded by a broad hyaline

Fic. 81. a and 5 Entyloma Calendulae. a mycelial FIG. 82, Development of the spores 0. Ustilayo
filament with two young resting-spores. 64 resting-spore Tragopogonis; successive stages of the development
germinating; the front pair of primary sporidia in the according to the letters. @ sporogenous branch, just
whorl shows conjugation at the base. c and d Extyloma appearing on the surface of the young corolla of Trago-
Ungertanum, De Bary. cagerminating resting-spore; four pogon pratensts and beginning to form a tuft of branch-
primary sporidia conjugating by pairs at their apices. the lets. @ spore-tuft with several ripe spores, the episporium
same specimen seven hours later; commencement of the of which is coloured a dark violet and furnished with

bjointing of a dary sporidii idi on each reticulate thickenings. Magn. 300 times.

pair. Magn. 600 times.

gelatinous sheath (Fig. 82 2, c), and forms inside it a relatively small almost homo-
geneous and strongly refringent nucleus-like body. The definitive membrane of
the spore is then formed on its outer surface inside the gelatinous envelope, and
developes with the protoplasm into the comparatively large spore. As growth
proceeds the gelatinous sheath becomes more delicate and paler and disappears
altogether when the spore has reached maturity (d-d).

In the genera Urocystis, Sorosporium, and Tuburcinia the ripe spores are
joined together from two up to a considerable number in a cluster and are each
provided with a persistent or temporary special envelope. The development of the
cluster is not clearly known in all points. In Urocystis, according to Wolff and Winter,
the first beginning of a cluster is represented by a turgid and often curved branch from

176 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

the sporogenous hypha, in place of which a group of 2-4 delicate cells subsequently
makes its appearance after some intermediate stages which have not been clearly
ascertained; these cells are firmly united together and develope into spores, and
the group in its early stages has slender curved hyphal branches growing close
round it and forming an envelope for it. The hyphae of the envelope are divided
by transverse walls into short cells, most of which disappear as the spores ripen,
while a small number of cells varying with the individual develope into persistent half
lenticular envelope-cells, which lie close upon the group of spores as it matures.
The envelope appears to be formed at earlier or later periods in the development
according to the species, and the division of the spore-primordia to be sometimes
omitted, as only one ripe spore is not unfrequently found inside a group of envelope-
cells. According to Prillieux the process is much more simple; a number of
sporogenous hyphal branches become felted into a knot, and one or more branches
form a spore acrogenously, as in Tilletia, while the cells of the other branches
develope more or less perfectly into an envelope; but the envelope may be omitted
and then the spore is formed as in Tilletia. My older observations agreed pretty
well with these statements of Prillieux, but it would be desirable to have other
confirmation of them.

The commencement of a spore-cluster in Sorosporium and Tuburcinia, ac-
cording to Woronin, is also a short turgid lateral branch, sometimes perhaps two
branches, lying close upon one another. Every such primordium is then wrapped
up in a tangle of the many ramifications of slender hyphal branchlets, which become
woven together into a round compact coil. No further differentiation is at first
perceptible in the coil. When it has grown to a certain size its central portion
consists of a compact group of delicate polyhedric cells, which then ripen all
together into perfect spores without further perceptible division by multiplication.
The group is at first still enclosed in a dense many-layered web of hyphae, but this
disappears as the spores mature, in Sorosporium with a previous conversion into
mucilage. The first formation of the group of spores in the coil is not clearly
ascertained. Frank’s statement, that each spore comes from a turgid cell of one
of the original filaments of the coil, and that the other parts then form the temporary
envelope, is plausible but requires more distinct proof. We learn from Fischer
von Waldheim that spores sometimes occur even in Sorosporium Saponariae, which
are abjointed singly and without envelope on the extremity of a hypha as in Tilletia.
If these spores really belong to Sorosporium, as they must be supposed to do without
proof to the contrary, and not to a parasite of the plant, Frank’s view finds in them
material support.

The development of the spores has not been closely followed in the genera
Thecaphora and Schizonella, Schröt., which certainly come near to Sorosporium.

Section LVI. The single ripe spore of the Ustilagineae is usually round or
polyhedric and has the ordinary structure of firm Fungus-spores,—a delicate colourless
endosporium enclosing the protoplasm, and a stout episporium, which in most species,
and also in a form of Entyloma distinguished as Melanotaenium, is dark-coloured,
and in many has a delicacy of structure and superficial marking which is character-
istic and useful for the discrimination of species; in some cases it has a distinct
germ-pore. It is only in the majority of the Entylomeae that the thick stratified

CHAPTER V.—COMPARATIVE REVIEW.—-USTILAGINEAE. 177

episporium is almost or altogether colourless. The envelope-cells which adhere
to the spores in Urocystis have likewise pale-coloured membranes at the time of
maturity, and their contents are almost entirely watery.

The germination of the resting-spores takes place when they are sufficiently
supplied with moisture and have absorbed it to a sufficient degree. The form
differs according as only water is supplied to the spores or nutrient matter also
dissolved in the water,

In the first case a short germ-tube is emitted, which takes the protoplasm of
the spore and developes into a promycelium in the sense of section XXXI (p. 111).
In most species the promycelium remains in connection with the membrane of the
spore, in a few, as Ustilago Vaillantii, it soon separates from it. To this rule of
development there are a few individual and specific exceptions which will be con-
sidered presently. The further development is as follows :—

1. Shoots are put forth acrogenously or laterally at the cost of the protoplasm
and are abjointed; these in the terminology
which has been proposed would be sporzdza
(of the first order). The particular forms
which their development assumes vary much
in the several speciés; the chief ones, with
which isolated intermediate or divergent kinds
can easily be connected, are these :—

a. A whorl or circle of narrowly cylin-
drical or subulate sporidia (‘ Kranzkörper ’)
shoots out from the obtuse and compara-
tively broad apex of the promycelium. They
appear simultaneously; their number in a
whorl is different in different species and in-
dividuals, varying between 4 and ıo. This
mode is characteristic of most species of En-
tyloma (Fig. 81), and for Tilletia (Fig. 83),
Tuburcinia, and Urocystis.

5. The promycelial tube is divided by ai pen ar ir ee
transverse walls into a series of two or more en ee
short cells, and from these are abjointed, nein. Kar Mg
usually at their acroscopic extremity, a number
of elongated or rod-like shoots as sporidia. This is the process in Tolyposporium
Junci, Woronin, and in many species of Ustilago, for instance in U. Tragopogonis
(Fig. 84 2), U. flosculorum, U. utriculosa, U. Cardui, U. Kühniana, and some others.

c. The spore emits a simple, or in a very few cases a branched, short, slender
promycelial tube, and from this is abjointed one cylindrico-fusiform sporidium
or several in a row one after another (Ustilago longissima, Fig. 84 A, Thecaphora
Lathyri according to Brefeld).

2. The slender promycelial tube, which sometines puts out one or two branch-
like protuberances, is divided by transverse walls into a few cells from which single
sporidia are abjointed or sometimes none. This is the case with Ustilago Carbo
(Fig. 84 C), U. destruens, and, according to Woronin, with Thecaphora hyalina.

4, ° N

178 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

The abjointed sporidia then unite in pairs in many species, either before or after
their separation from the promycelium. They unite by means of short transverse
processes, which may be placed at the point of insertion or at the apex or in the
middle, and form double cells, as is shown in Figs. 81, 83, 84 3. Coalescence by
pairs takes place also in the cases which come under No. 2 between the segment cells
of the promycelium. Adjacent cells unite with one another by means of short
processes arising near the partition-wall and forming with one another a short lateral
excrescence (Fig. 84 C left), through which the protoplasm of the two cells coalesces
after disappearance of the separating membrane. Communication is established
between cells which are not next neighbours by larger lateral branches, which may
form curved tubes or loops on a promycelium or even transverse bridges between two
promycelia.

The simplest form in which the development proceeds is by the production
at a spot in the conjugated pair of a slender germ-fube with acropetal growth, which
gradually receives the whole of the protoplasm of the two cells (Fig. 83 x); it has
been shown that in many species this tube can penetrate into the phanerogamous
plant which is its proper host, and there develope a mycelium which produces new
resting-spores ; it may therefore be shortly described as an zuezpien? mycelium or
mycelial primordium.

FIG. 84. A Ustilago longissima, Tul, germinati BU. Tragopogonis, C U. Carbo, Tul. ~ promycelium, s primary
poridia. Further ion in the text. .4 magn. nearly 700, 3 390, C more than 390 times,

The process is more complicated in Tilletia, in many species of Entyloma,
in Tuburcinia Trientalis, and as a general rule in Urocystis Violae, where a (secondary)
sporidium is acrogenously abjointed on a short lateral branch from the conjugated pair
(Figs. 83 s’, 81 d), which then gives rise to the incipient mycelium.

Deviations from the above course of development occur under otherwise similar
conditions in individuals of the species in which this development is the almost
invariable rule. Firstly, the germ-tube which proceeds from the resting-spore may
assume the characters not of a promycelium as described above, but of an incipient
mycelium with acropetal growth but not producing sporidia. Secondly, the conjuga-
tion of sporidia of the first order in pairs may be omitted, but the sporidia may still
put forth tubes which are similar in conformation to the incipient mycelium ; this may
happen to all or to a majority of the primary sporidia of a whorl in some species, for
instance, of Entyloma, or, when the number of the members of a whorl is uneven, to
one sporidium, while the others conjugate in pairs.

These phenomena, which are individual exceptions in the cases which we have
been hitherto considering, are the prevailing and even the invariable rule in another

CHAPTER V.—COMPARATIVE REVIEW.—-USTILAGINEAE. 179

series of forms. Here we may have formation of sporidia according to one of
the above modes or one like them, but without their conjugation, as in Ustilago
Maidis, U. Vaillantii, U. longissima, and in Entyloma Magnusii, Wor.; or there is no
formation of sporidia, but production of a germ-tube from the resting-spore which
shows the growth of an incipient mycelium without conjugation of any of its segments,
as in Sorosporium Saponariae according to Woronin.

The germination of the resting-spores in the nutrient solutions mentioned
on p. 127 has been recently studied by Brefeld in great detail. In some species it is
easier and more rapid in these solutions than with only a supply of pure water, and
generally so far differs from the process as described above, that luxuriantly vegetating
forms take the place of the short-lived products developed at the expense of the
protoplasm of the spore, and that these can continue to grow on without change of
shape and without limit if supplied with sufficient nutriment. The form which they
assume depends on the species; either the promycelium which begins in the manner
above described continues to develope like the Sprouting Fungi (see page 4), or the
germ-tube of the resting-spore grows into a branched filamentous mycelium from
which spores are then abjointed in the fluid itself or on branches which rise into the air.
Ustilago antherarum, U. Carbo, U. Maidis, and U. Kühniana are beautiful examples of
‘the sprouting form; U. destruens of the sporogenous mycelia.

There are species intermediate between the two forms, a detailed account of
which will be found in Brefeld. U. destruens itself may to some extent be regarded
as an intermediate form, since some of its spores germinate by sprouting in the
nutrient fluid, while others develope a mycelium which vegetates and ramifies in the
fluid, and sends up erect branches into the air from which elongated spores serially
developed as branched chains -of sprouts are abjointed (see p. 66). In the case
of Tilletia Caries, Entyloma, and Thecaphora Lathyri the resting-spores have not
been seen to germinate in a nutrient fluid, or the product of the commencing
germination soon dies away; on the other hand when primary or secondary sporidia
from plants which have germinated in water are placed in nutrient solutions, there is
a copious formation of mycelium and acrogenous abjunction of spores on erect
aerial branches of the mycelium; these spores in Thecaphora are like the primary
sporidia of germination in water, those of the other species mentioned are like the
secondary. _

Geminella Delastrina differs from the rest, as Schröter found, in the acrogenous
serial abjunction of roundish sporidia on the short promycelial tube in water; the
further development of the spores was not observed. The same species produced
large mycelial bodies in Brefeld’s nutrient solutions, but their further history also was
not ascertained.

Section LVII. Finally, in some Ustilagineae spores of another kind are
produced on the mycelium forming the resting-spores and inhabiting the host-plant;
these may be termed provisionally gonzda. Schröter found that in a number
of species of Entyloma, E. Ranunculi for example which is common on Ranunculus
sceleratus and R. Ficaria and especially E. serotinum on Symphytum officinale, the
mycelium which lives in the leaves sends a large number of short branches
often closely crowded together into the air, partly through the stomata, partly through

the lateral walls of the epidermis, and that from the extremities of these branches
N 2

180 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

single spores (or perhaps several successively) are abjointed. The spores are narrowly
fusiform in shape, like the secondary sporidia of the promycelium, and it may be
assumed, though it has not been observed, that their mode of germination is the
same. They are formed on the mycelium before the resting-spores, and appear to
the naked eye as a slight sprinkling of flour or mould on the spot which is attacked
in the leaf.

The most remarkable case of this kind was observed by Woronin in Tuburcinia '
Trientalis, The resting-spores of this Fungus germinate in late autumn. The
mycelial primordia produced from the secondary sporidia penetrate into the young
subterranean shoots of Trientalis destined to pass the winter, and develope a mycelium
which also hibernates in their parenchyma. Next spring the mycelium spreads
through the whole of the shoot as it unfolds, and at first forms gonidia on the under
side of its leaves and afterwards the cluster of resting-spores, but more in the
stem than in the leaves. The gonidiophores are branches of the intercellular
mycelium and come out to the air through the stomata and lateral walls of the cells of
the epidermis, covering the whole of the surface of the leaf with a white down.
They are unbranched and subulate in form, and from the apex of each several
spores (gonidia) are successively abjointed one after another, which are pear-shaped
and not fusiform like the sporidia of the promycelium. Germ-tubes are put forth
by the gonidia on the moist surface of a leaf of Trientalis and penetrate into it, and
develope mycelia which are confined to small spots in the leaf, where they form clusters
of resting-spores but not gonidia.

Section LVIII. According to the above well-ascertained facts the course of
development in the Ustilagineae (in species of Entyloma, in Ustilago Carbo, and Uro-
cystis occulta), where the process is the simplest, appears to be, that the resting-
spore produces a promycelium, and the promycelium the conjugating pairs, and the
ınycelial primordia which proceed from them enter and develope in the host-plant
and produce fresh resting-spores. The first complication is caused by the production
of mycelial primordia, not directly from the conjugating pairs, but from secondary
sporidia proceeding from them, as happens almost invariably in some species of
Entyloma and in Tuburcinia Trientalis. Then comes in Entyloma Ranunculi,
E. serotinum, and in Tuburcinia Trientalis the interpolation of gonidia which are
formed on the endophytic mycelium and can produce similar mycelia. If we regard
the resting-spores as carpospores in the sense. of section XXXIV, a point which will
be discussed further on, the secondary sforzdia must be termed gonidia which have
been interpolated in the course of the development. Lastly, a mycelium can also
be produced on any dead substance which yields suitable nourishment and gonidia
on the mycelium, and it may at least be assumed that the gonédia are capable of
reproducing a mycelium forming carpospores. I have purposely avoided the general
use of the word gonidium in the preceding pages, though it will have to be used from
this time, in order to show by one example how the same object may and must have
different names when considered from different points of view and in different
connections.

The facts that have been certainly ascertained are only these: that the species,
whose course of development has been really followed throughout, Ustilago Carbo,
-D. destruens, Tilletia, Tuburcinia Trientalis, Entyloma and Urocystis occulta, all show

CHAPTER V.—COMPARATIVE REVIEW.—USTILAGINEAE. 181

conjugation of the segments of the promycelium, or primary sporidia, and that in
Urocystis Violae, whose development was also fully observed by Kühn, conjugation
must be supposed to take place from Prillieux’ figures, though it is not expressly de-
scribed. On the other hand there are species, which, according to our present observa-
tions, do not conjugate. But we have no complete observations of their development;
only from the data which we possess, and the positive result of Kiihn’s extended re-
searches into the infection of host-plants with Urocystis Maidis, it must be supposed
that the endophytic sporogenous mycelium is in this case developed directly from the
resting-spore or from interpolated gonidia which do not conjugate. Accordingly the
course of development, apart from certain special formations and complications which
vary in the different species, would be the same in its main features in the entire
group of the Ustilagineae up to the difference which lies in the presence or absence
of conjugation.

What importance is to be assigned to this difference is open to discussion. The
pairing I have formerly called conjugation and do so still, thus giving expression to
the view, that it may or ought to be considered as analogous with a sexual process.
Brefeld does not admit this and explains it to be an analogous phenomenon to the
coalescence of vegetable cells, especially young germ-tubes (see on page 2). In
such cases as these no decisive argument for or against is to be found in the phe-
nomenon in itself, but we must look about for indirect grounds of probability. Mine
are as follows, if I confine myself to cases that are thoroughly known. First, the
almost invariable occurrence of pairing under the normal conditions of germination ;
the conditions, I mean, to which the species is actually adapted in nature. The
conditions are those for germination in water in the case of Tilletia, the species of
Entyloma, Urocystis, and Tuburcinia Trientalis, as has been already shown; and here
pairing takes place so promptly that it is not easy to keep primary sporidia from
uniting, if we disregard some special exceptional cases mentioned above. But these
cases are of the kind which prove the rule. Secondly, the great predominance of
union in pairs. The sporidia which are placed close to one another in whorls in
Tilletia, Entyloma, Urocystis, and other genera unite, almost without exception, in
pairs only, and where there is an odd sporidium it usually does not conjugate,
though its union with some pair would be easy, one might almost say would be very
natural. The segments of the promycelium of Ustilago Carbo conjugate when they
are immediate neighbours in a mode similar to the ‘ clamp-connection’ of page 2;
under different local relationships pairing is effected in a different way, as by loop-
unions between two segments of a promycelium which are separated by a pair which
have already united. These facts show that a change usually takes place in a pair
after conjugation which renders a second union difficult or impossible, while it
introduces the further development. All these are phenomena which find their
analogy, as far as we know at present, only in sexual processes, or, as it may be
briefly expressed, in sexual processes of conjugation, and must be interpreted by
them, till we obtain further knowledge. The case is different in the coalescence of
germ-tubes, which are the nearest comparable. A glance at Fig. ı shows that in
that case coalescence may take place between any number of spores or may even be
omitted, while the further development is the same in kind, but shows different
degrees of strength according to the number of the germs which have coalesced. It

182 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

is true that conjugation of more than two primary sporidia has been observed in the
plants which we are considering; in Tilletia, for instance, and Ustilago Tragopogonis;
but these exceptional cases are comparatively rare and would only confirm the rule,
even if similar exceptions in typical sexual conjugation, as in Zygnema and Acetabu-
laria, were unknown,

The reasons which Brefeld alleges against my conception of the pairing, as far as
I understand them, are these. Pairing occurs in germination in water; it does not
occur when the primary sporidia of Tilletia, for example, are placed in nutrient
solutions before pairing can begin; it also does not occur in Ustilago Carbo and
similar germinating species, if they germinate and sprout in a nutrient solution. But
when the supply of food is exhausted, pairing sets in in many species and is followed
by the formation of incipient mycelium. A fresh supply of food again sets up
gonidial sprouting. This shows that the uniting cells are not sexual organs in
themselves incapable of germination, for ‘according to our present ideas with
respect to the essence of sexuality” no such change in the properties of sexual cells
could be brought about by changes in the nutrition. The answer to this is, that,
according to our present knowledge, the only processes of conjugation which can be
here brought into comparison, and which are to be distinctly regarded as simplified
analogues of sexual processes, consist solely in the characteristic coalescence in
each case of two cells into one capable of further development. What further
‘essence ’ is involved in the matter we do not know. Many of these conjugating
cells are not capable of further development without conjugation, the gametes, for
example, of many Chlorophyceae; but this is not the case with all. I will not
mention the Phaeosporeae, which supply examples of the opposite behaviour, because
the circumstances in their case are not quite clear and are to some extent open
to question. But Rostafinski and Woronin found that the swarm-spores developed
from recently matured resting-spores of Botrydium granulatum? do typically and
necessarily conjugate, and that the same swarm-spores germinate without con-
jugation when they proceed from resting-spores which are more than two years
old. A change therefore takes place in these cells, affecting those properties in them
with which we are at present concerned, through the influence of external causes
which must be closely connected with processes of nutrition. Even highly differen-
tiated sexual cells may be capable of further development when fertilisation is
prevented, as is shown by the oogonia with unfertilised oospheres of Pythium
megalacanthum? which send out strong germ-tubes. We see therefore that the
exceptional cases to the pairing which is the general rule in the Ustilagineae, whether
artificially produced or spontaneous, are not opposed to phenomena known to occur in
organs which are undoubtedly sexual.

That there are species which do not pair cannot affect our decision with regard
to those which do; moreover it is well known, that in other groups of Fungi organs
strictly homologous have a distinct sexual function in some species and may be
asexual in others, as we learn by comparison of the Peronosporeae and those Sapro-
legnieae which are without antheridia,

* Bot. Ztg. 1877, p» 662.
® Bot. Ztg. 1881, p. 543.

CHAPTER V.—COMPARATIVE REVIEW,—USTILAGINEAE. I 83

--The strongést argument which could be advanced at the present time in support
of Brefeld’s view is, that, according to his statements, species like Ustilago longissima
show pairing in the ‘ gonidia’ which are produced in nutrient solutions and sub-
sequent formation of mycelial primordia under the given conditions, while pairing
is not observed when germination has taken place in water. But the course of
development is not perfectly known in these species, and they cannot be a standard
for judging of those which are thoroughly known. And what we know about these
species, especially Ustilago longissima, gives ground for suspecting that even in them
pairing is a necessary preliminary to the formation of mycelial primordia capable of
infection, and that it occurs in opposition to the case of Tilletia only under special
conditions of nutrition which have yet to be ascertained.

In whatever way the question of the sexual value of the pairing may ultimately
be decided, it is at all events a characteristic fact in the cases in which it occurs and
cannot be disregarded.

The homologies in the course of development of the Ustilagineae are quite clear
within the group itself, and require no further discussion. It is moreover obvious,
and the fact is expressed by the terminology which has been partly anticipated, that
this development corresponds in general to that of the preceding groups, and resting-
spores therefore may be compared with the resting-oospores, oospores or carpospores
of the Peronosporeae and Entomophthoreae, &c.; the comparison of the simpler
forms, especially Entyloma and Tilletia, confirms this view. If this comparison is
accepted, we have at once a justification of such terms as gonidia, &c. The resting-
spores or carpospores, as they may be presumed to be, of the Ustilagineae are
formed, it is true, asexually, while the contrary is the case with those of the Perono-
sporeae; but this, as we have learnt from the Saprolegnieae, affords no criterion for
the determination of the homologies. It is not easy to see why it should be the
Entomophthoreae particularly to which the Ustilagineae must be considered to
approach nearest, as Brefeld maintains’; it might very well be the Peronosporeae.
But while the agreement between the groups makes itself thoroughly felt, a near
approximation of them is in most points impossible; this can be brought about in
many places, if we put one thing forward and disregard another, but we gain
nothing by these arbitrary proceedings. If, on the other hand, we look for the points
which are distinctly characteristic of the Ustilagineae, the most prominent is that of
the conjugating pairs of cells. This phenomenon recurs, so far as is known, only
in one form not belonging to the Ustilagineae at the same place in the course of the
development and in a quite similar form, namely, in Protomyces macrosporus. There
is only one important difference between the two cases; in Protomyces the con-
jugating cells are of endogenous origin, in the Ustilagineae they are acrogenously
abjointed, but this difference is no real objection to the homology, for it occurs in a
similar form among the undoubtedly homologous gonidia in the Mucorini
(section XLII); the pairs of cells in Protomyces are formed endogenously, like
‘the gonidia of Mucor, those of the Ustilagineae acrogenously, like the gonidia of
‘Chaetocladium. Hence Protomyces macrosporus appears to be in every respect very
nearly related to the Ustilagineae, and its resemblance in habit to species of Entyloma

1 Brefeld, Schimmelpilze, IV, p. 165.

184 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI,

is in harmony with this. We should be able to connect the Ustilagineae more
closely with other groups, if we could do the same with Protomyces, and for this
purpose the approximation of Cladochytrium is important. In these two forms
indeed there is complete agreement except in two points. First, the propagative cells
formed in the resting-spores are swarm-cells in Cladochytrium, but not in Protomyces;
but this difference is quite unimportant for the present question, because strictly
homologous spores of most closely allied species may behave differently in this
respect. Secondly, and this is important, there is no conjugation or pairing, as far
as we know, in Cladochytrium. If further researches only confirm this fact, then
there is a gap in the chain of connection which is not bridged over, but this has yet
to be determined. According to the data before us it would appear that the best line
of connection of the Ustilagineae with other groups must lead through Protomyces
and Cladochytrium to the Chytridieae or to the group of the Chytridieae to which
Cladochytrium belongs (see page 165). The Ustilagineae therefore, considered
phylogenetically and in connection with what was said above of the Chytridieae, may
be regarded as a more highly developed group proceeding from the Chytridieae,
whose development has advanced from the simpler forms like Entyloma in two
diverging directions, and has reached its highest point on one side in the cluster-
forming Sorosporia and Urocystes, and on the other in the compound sporophores
of Sphacelotheca and other forms. The same considerations arise moreover if
we connect the Ustilagineae with other groups, such as the Entomophthoreae,
which again can only be effected through Protomyces and Entyloma. And
whichever view we adopt, if we accept our present data, we must look upon conju-
galion or pairing in Protomyces and the Ustilagineae as a special new phenomenon,
that is, as one which has nothing homologous with it in the groups supposed to be
allied to them. If it has its analogue in them in sexual processes or processes of
conjugation, if, in other words, it is a sexual process, this process makes its
appearance in the Ustilagineae at a place in the course of the development o/Aer
than that which it occupies in groups before considered; in these the resting-spore
is always the direct result of the sexual process, while its homologue in the Ustila-
gineae is of asexual origin.

It is superfluous perhaps to say in conclusion that the Ustilagineae cannot
at present be brought into closer connection with the succeeding groups, as the
following sections will show.

Historical remarks. Brefeld (Schimmelpilze, IV) and myself (Beitr. IV) were the
first who attempted recently to settle the homologies and the position of the Ustilagineae
in the system in the sense indicated in the text. The old writers placed them next the
Uredineae on the ground of external resemblance. I pointed, out as early as 1853
(Brandpilze, p. 28), that this position was inadmissible. When I attempted, seventeen
years ago, in the preface to the first edition of this work, to give a short survey of the
groups of Fungi according to the knowledge then before us, I followed the old custom
of placing the Uredineae and Ustilagineae together, under Fries’ name of Hypodermii,
expressly quoting that writer, because the state of our knowledge at the time did not
allow of my substituting a new and safer view for the old one. I write this in cor-
rection of statements which make me the author of Fries’ division Hypodermii, or which
even seem to make it a reproach to me that I retained that division when nothing else
was possible, and abandoned it as soon as our increased knowledge permitted me
to do so.

CHAPTER V.—COMPARATIVE REVIEW.—ASCOMPCETES. 18 5

Literature :—

Protomyces.
DE Bary, Beitr. z. Morph. u. Phys. d. Pilze, I, where the older literature is cited ;—Id.
in Bot. Ztg. 1874, p. 81.

Ustilagineae.

LEVEILLE in Ann. d. sc. nat. ser. 2, XI, 1839.—Article Urédinées in d’Orbigny’s Dict.
d’hist. nat.

TULASNE, Mémoire sur les Ustilaginées comparées aux Urédinées (Ann. d. sc. nat. sér.
3, VII, 1847) ;—Id., Second Mémoire sur les Urédinées et les Ustilaginées (Ann.
d. sc. nat. sér. 4, II).

DE Bary, Unters. ii. d. Brandpilze, Berlin, 1853 (this work and Tulasne’s memoirs give
the older literature) ;—Id., in Flora, 1854, p. 648 ;—Id., Protomyces microsporus u.
seine Verwandten in Bot. Ztg. 1874, p. 81 (Entyloma).

J. Ktun, Die Krankheiten d. Culturgewächse, Aufl. 2 unaltered, Berlin, 1859 ;—Id. in
Fühling’s Landw. Zeitsch. 1879, p. 81 (according to Just’s Jahresber.).

A. FISCHER v. WALDHEIM, Beitr. z. Biol. u. Entw. d. Ustilagineen (Pringsheim, Jahrb.
VII, 1869). This work contains copious accounts of the older writers and literary
minutiae. See also another work by the author not properly belonging to this place,
Les Ustilaginées et leurs plantes nourriciéres (Ann. d. sc. nat. ser. 6, IV).

R. Wo rr, Beitr. z. Kenntn. d. Ustilagineen (Urocystis occulta) in Bot. Ztg. 1876, p.
657 ;—Id., Der Brand d. Getreides, Halle, 1874 ;—Id. in Bot. Ztg. 1874, p. 814.

G. WINTER, Einige Notizen ii. d. Familie d. Ustilagineen (Flora, 1876, Nr. 10).
J. SCHRÖTER, Bemerkungen und Beobachtungen ü. einige ee asi (Cohn’s Beitr.
z. Biol. II, pp. 349 and 435).

E. PRILLIEUX, Quelques observations sur la formation et la germination des Spores des
Urocystis (Ann. d. sc. nat. ser. 6, X, 1880).

A. B. FRANK, Die Krankheiten d. Pflanzen, Breslau, 1880, p. 419.

M. WORONIN in Beitr. z. Morph. u. Phys. d. Pilze, V, Frankf. 1882 (Tuburcinia u.
Keimungen).

M. Cornu, Contributions a I’étude d. Ustilag. (Bull. soc. Bot. de France, Aug. 1883) ;—
Id. in Ann. d. sc. nat. ser. 6, XV (1883),

ED. FISCHER, Beitr. z. Kenntn. d. Gattung Graphiola (Bot. Ztg. 1883).

BREFELD, Bot. Unters. ii. Hefenpilze, Leipzig, 1883.

ASCOMYCETES.
GENERAL CHARACTERS. SPOROCARPS.

Section LIX. The group of the Fungi known as the Ascomycetes contains
an enormous number of species, but all its members have their bodies composed
of branched hyphae which are always septate, and they are all distinguished by
the’ formation of their spores in asci, as has been described in section XIX, from
which peculiarity they derive their name. Putting aside the species which will
be noticed at the conclusion of the division as doubtful Ascomycetes, the asci
of this group are sporocarps in the sense of section XXXIII, or parts of sporocarps,
and in the latter case are often collected several or many together into hymenia
{section XII).

186 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

The sporocarps are formed and borne in some species on an inconspicuous
filiform mycelium, and then exhibit the characters of compound sporophores described
in sections XII and XIII. In other species they are produced and borne
on larger compound sporophores, each called a séroma, which take the form
in the different species of flat expansions, crusts, foliaceous or erect and branched
shrublike bodies. The general structure and conditions of growth of these forma-
tions, which are often of considerable size, have also been described above in
section XII. Well-known examples of them among the Pyrenomycetes are the
cushion-like or membranous expanded stromata of the ‘Sphaeriae compositae,’ i. e.
of the genera Hypoxylon, Diatrype, Ustulina, Epichlo&, and many others, and the
erect sporophores of the Xylarieae, Claviceps, Cordyceps, Thamnomyces with its
many bifurcations, and others. Of the Discomycetes which belong to this group
the most important are the Lichen-fungi with their disk-shaped and alveolate sporo-
carps; next, Rhytisma and its allies with
flat disk-shaped stromata, and perhaps too
the remarkable South American Cyttarieae
—spherical or club-shaped or gelatinous
bodies more than an inch in diameter
with the broad upper half covered with
deeply alveolate hymenia, regarding which
it is doubtful whether each is in itself a
sporocarp or a portion of the sporocarp
formed by the whole club-shaped stalk.

Two chief constituents may be dis-
tinguished in almost all the better-known
sporocarps of the Ascomycetes (Fig. 85) ;
one (c, s, a) is the ascus-apparatus and
consists of asci together with the hyphae

_ or cells from which they are immediately

Fic. 85. Ascobolus Jurfuraceus. Young sporocarp in es

median longitudinal section ; une derived, the ascogenaus hyphae or ascogenous
layer and the asl a shaded antheräal branch, 4-7 dasıe cells ; the other is the envelope-apparatus
matic representation from Sachs after Janczewski. which is formed of all the other parts of the
sporocarp. The two parts are necessarily

in the closest relation to one another from the purely morphological and also from
the physiological point of view, since the envelope-apparatus bears, protects, and
feeds the asci. The elements of the two parts may be most intimately united
and interwoven with one another in the mature sporocarp and in fact may be
difficult to separate or distinguish. Nevertheless the origin and growth of the
two parts are usually distinct from their first inception or at least in a very early
stage of the sporocarp, so that only similar parts, asci, and not elements of the
envelope, spring from an ascogenous hypha or ascogenous cell, and no asci from
the elements of the envelope. Exceptions to this rule are according to ac-
curate observations at least very rare. Former statements to the effect that. asci
and elements of the envelope, especially paraphyses, spring directly from the same
‘hyphae are in most cases certainly incorrect; even some recent statements, like
those regarding Pleospora and Ascodesmis, which will be noticed again in a

CHAPTER V.—COMPARATIVE REVIEW.—ASCOMYCETES. 187

later page, require a more searching investigation. But even if there are some
exceptions to the rule, and a good many cases require further examination, the
prevailing rule undoubtedly is that the two constituents of the sporocarp though
close to one another are independent in their origin and growth.

Eremascus, a typical Ascomycete of the simplest form, recently described by
Eidam, is remarkable for the entire absence of an envelope-apparatus.

Three chief forms of sporocarp in Ascomycetes may be distinguished according
to the arrangement and conformation of its two constituent parts, and the coarser
structure which results therefrom: the discocarp or apothectum and the pyrenocarp
or perzthecium, which are used to distinguish the Discomycetes from the Pyrenomycetes,
and the clecsfocarp, a form which remains closed. I use the words apothecium
and perithecium in the sense introduced by P. A. Karsten in his Mycologia fennica.

FIG. 8. A Usneabarbata, B Sticta fulmonacea. Portionsof thallus. a apothecia, / point of attachment to the
substratum, After Sachs. Natural size.

There are a few forms or small groups which cannot in strictness be arranged
under one of these three types, but must be placed along with them as peculiar
and exceptional cases. The accounts which we possess of the history of the
development, though imperfect, are sufficient to show that the above types are
distinguished more by habit in their advanced states than by any more fundamental
distinction.

Section LX. The distinguishing feature in the apothecium (Figs. 86-89, see
also Figs. 19, 22, 85, and 99) is, that the hymenium lies exposed on the surface
of the sporocarp while the spores are forming and maturing. The hymenium
itself, the discus, lamina proligera and sporigera of the old terminology, consists
first of the ascı, secondly of capilliform hyphal branches, the paraphyses---The

188 DIVISION IL—COURSE OF DEVELOPMENT OF FUNGI,

latter are placed perpendicularly to the surface of the hymenium, and terminate at
a uniform height on this surface, being crowded together in great numbers and
usually giving the hymenial layer its characteristic tint from the colouring of their
walls, or contents: not infrequently, especially in the hymenia of the Lichen-fungi,
they are united laterally and without gaps by the gelatinously thickened walls, so that
their lumina appear to be set in a homogeneous structureless jelly. The paraphyses
spring by their inner or lower extremities, that is, those turned away from the outer
surface as branches from a dense hyphal tissue beneath the hymenium, the subhymenzal
layer or hypothecium, which is then continued further downwards into the more
or less largely developed receptaculum or stipe of the apothecium, or at least
into an outer envelope, the exczpulum, which belongs to it, though it is not greatly
developed.

The paraphyses, together with the elements of the hypothecium which produce
and bear them and the receptaculum or excipulum, belong to the envelope-apparatus
of the apothecium. But the ascogenous hyphae take their course in the hypothecium,
being interwoven with the ele-
ments of the envelope; they
grow up in the commencing
apothecium from points of
origin, which will be described
more exactly in section LXIII,
in the direction of the hymenial
layer, and afterwards spread
themselves out near the under
surface of the disk with copious
branching which follows the
progressive growth of the whole .

apothecium, and thrust the
FIG. 87. Anaptychia ciliaris. Médian section through an apothecium; A hy- its 7
inp teed ee ae cae All bests bene to thet, extremities of their branches

which forms a rim round the excipulum at ¢; 7 medullary layer, » rind, g its ae. 1
After Sachs. Magn, about so times. eits Algae’ of the last order successively

in between the paraphyses to
form the asci. In many of the species belonging to this division the ascogenous
hyphae can scarcely be distinguished from the elements of the envelope which
surround them by anything but the formation of asci which belongs to them only.
In others, especially in many but not all the Lichen-fungi, in which Schwendener
first discovered them, they are distinguished from the surrounding tissue by their greater
thickness, by the abundance of their protoplasm, and by their membrane turning
blue after treatment with potash. The development of the envelope-apparatus
is always in advance of the ascus-apparatus, though the latter may have begun to be
formed at the same time; the paraphyses are therefore always the parts which
are first present in the hymenium. The asci make their appearance after them
and grow vertically upwards between them in the direction of the surface, reaching
it usually or rising above it only as the spores become ripe (see section XXII).
Only a few asci appear at first, then their number increases through successive
branching of the ascogenous hyphae, often to such a degree that the paraphyses
are displaced and become indistinguishable.

CHAPTER V.—COMPARATIVE REVIEW.—ASCOMYCETES. 1 89

The Ascomycetes which bear apothecia are well known under the name of
Discomycetes and Gymnocarpous Lichens. The apothecia in the largest species
are compound sporophores of considerable size with limited growth in the direction of
the apex or margin, club-shaped or cochleariform in Geoglossum, Spathulea, &c., a
stalked cap in Morchella, Helvella, Leotia, Verpa, and others. The early stages
of the development of these bodies are little known, but they may be ranked as
sporocarps with the forms which will be mentioned directly on account of similarity of
structure, and the presence of intermediate forms, especially the large stalked Pezizae.
The most characteristic and frequent form is that of the roundish or oblong disk-shaped

FIG. 88. Anaptychia ciliaris. Small piece of a vertical section through an 'hecium ; #7 medullary layer of
the thallus, 7 subhy jal layer, 2 with asci between them. The Is 1-4 i
stages in the development of the spores. After Sachs. Magn. sso times,

hymenia, which are plane, convex or concave, and in the latter case usually like a bowl
or cup, on a Stalked or sessile receptaculum or excipulum, as in the Pezizae and in most
gymnocarpous Lichen-fungi. The usual mode of growth by gradual advance towards
the apex or margin does not prevent the appearance of intercalary surface-growth, which
does in fact occur very often and with very varying distribution of the preferred places
of growth ; and this may produce a variety of changes in the original shape of the
hymenial surface, such as splittings and prolifications, the latter producing a very peculiar
and characteristic form in Gyrophora!. For the details of these phenomena, which
-have yet to be more certainly ascertained in many points, we must refer the reader to

1 See Krabbe in Bot. Ztg. 1882, Nr. 5-8.

190 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI,

the special literature. The most important and most general phenomenon of intercalary
growth in the surface of the hymenium consists in the introduction of new asci already
mentioned, which goes on for a long time at all points. This is the cause of the long
continued superficial growth of many hymenia.

Some smaller disk-shaped apothecia, those for example of Ascobolus and Pyro-
nema, show no marginal progressive growth or only a trace of it. In this respect
and in some others also their development approaches that of the Pyrenomycetes.

FIG. 89. Lecauora subfusca. Median section through a young apothecium, swollen up in ammonia, somewhat
di: i d; h i eexci from which spring the paraphyses represented by strokes run-
ning ‘ically ds A, sh gg‘ hyphae giving rise to the asci, 7 rind, 2 medullary layer of the thallus which
forms a rim round the excipulum. The round bodies are the algal cells contained in the thallus. Magn. 190 times.

This is the case in a still higher degree with the ascocarps of the Hysteri-
neae and Phacidiaceae, the structure and development of which have been but
little examined. According to Hartig’s account of Hypoderma macrosporum and
H. nervisequum and my own imperfect observations on some species of Rhytisma and
Phacidium, the hymenia in these groups are formed in the interior of flat sclerotioid
Fungus-bodies (zyloma, see p. 43), and become exposed at the time of maturity,
when the layer of tissue over the surface of the hymenium separates from it

FIG. go. Thelidi: is A perithecium borne on the thallus; @ group of Algae, » the part of
the thallus in the substratum which has no Algae, 9 the perithecium in median section diagrammatically repre-
sented and slightly magnified. 3 a group of Algae with hyphae winding round them. After Stahl. Magn. 480
times.

and tears asunder in the mode which has often been described in the accounts of the
different genera. In this case there are at first only paraphyses present in the hymenia ;
the origin of the asci which are introduced between them has yet to be exactly
ascertained.

Section LXI. The perithecia of the Pyrenomycetes (Fig. 90, see also
Fig. 44), may be described as cup-shaped discomycetous sporocarps with the margin

CHAPTER V.—COMPARATIVE REVIEW.—ASCOMYCETES, 191

incurved so as to form a narrow-mouthed cavity. They are generally roundish
or flask-shaped, and they are seldom more, usually less, than 1 mm. in height.
They are- bounded on the outside by the wa// which encloses an asciferous
hymenium, and are furnished in the full-grown state with a narrow aperture or ostiole
(ostéolum, pore), which is a canal passing through the wall and serving for the discharge
of the spores (section XXIII). The ostiole usually lies at the apex in reference to
the point of origin of the perithecium, seldom at the side (Pleurostoma, Tul.) or at
the base (Melanospora parasitica). In many species the orifice is drawn out into
a conical or cylindrical neck (tubulus of Tode), through the middle of which the
canal passes, and which in some cases, as in the Valseae, Sordarieae, and
Melanospora, may be more than ı mm. in length. The asci are inside the
perithecium on the side away from the ostiole, and are borne on the ascogenous
hyphae or cells from which they successively shoot out, as in the Discomycetes.
With this mode of formation it is possible for some hundreds of asci to be formed
in the small space of some perithecia, new ones continually appearing in place of
the ripe ones which have discharged their spores. The asci together either exclusively
form the hymenium or are at least its most essential parts; the hymenium either
occupies a narrow bit of surface opposite the ostiole of the perithecium, on which
the asci grow as a small tuft parallel and erect towards the ostiole, or is spread
over a larger, sometimes over the largest portion of the inner surface of the wall,
and the asci then converge radially towards the middle line of the perithecium.
Here too the asci and ascogenous organs alone form the ascus-portion of the
perithecium; all the other parts belong to the envelope-apparatus; in structure
therefore they are on a smaller scale than the envelope-apparatus and in their
main features they are like cup-shaped apothecia.

The wall is formed of a dense hyphal weft or pseudo-parenchyma, in Pleospora,
according to Bauke, of actual parenchyma-like tissue. It is usually differentiated
into a stronger often sclerosed outer layer, the thickness of which varies in the
individual, and which can produce rhizoids and various other hair-structures on peri-
thecia which stand detached on the mycelium, and an inner layer with delicate and
‘often large cells. In some perithecia inserted in stromata, for instance in Tulasne’s
Dothidea, in Claviceps, species of Cordyceps and Polystigma, this differentiation does
not occur or it is not very distinct, and the wall is formed almost throughout
of delicate cells. In its quite young state the wall is entirely closed round
the initial organs of the ascus-apparatus and its ultimate investment, which latter
will be described below. The ostiole is not formed till the development is more
advanced, and it appears as an intercellular passage in the originally close
tissue; it is partly schizogenetic by the separation of persistent tissue-elements
in consequence of unequal growth, partly lysigenetic by the dissolution of a strip
of tissue lying originally in the direction of the canal. The two processes seem to
be often combined, and it is not easy to decide whether there is a solution of small
strips of tissue along with the schizogenetic formation, or not. The ostioles in
Sordaria, Melanospora, Claviceps, Epichloé, in Eutypa also according to Füisting', and
Stictosphaeria are very largely schizogenetic; Füisting finds the lysigenetic formation

1 Bot. Ztg. 1868, pp. 369, 641.

192 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI,

in Diatrype, Verrucaria, Endocarpon, Pyrenula, and in a very striking manner
in Massaria and its nearest allies. In the latter the perithecia are formed inside
a flat stroma which lives in the rind of trees, and the orifice is due to the disorgan-
isation and ultimate disappearance of a comparatively thick strip of tissue outside
and over the apex of the perithecium, together with the tissue of the rind enclosed
by it.

The neck is of course a prolongation of the wall, chiefly of its outer layers; this
appears very distinctly in some perithecia developed in the interior of the thallus, as
in Xylaria, the Valseae, Verrucaria, Endocarpon, and species of Pyrenula’, where
it pierces through the surface of the thallus and comes out to the air. Its de-
velopment is either rapidly completed at an early period, or it is capable under
certain conditions of a long-continued apically progressive or intercalary growth
in length, and while this is proceeding it is, especially in Sordaria?, in a high
degree heliotropic; this variety in the mode of development depends on the species
and genus.

The asc¢ are inserted in the places in the delicate tissue of the inner wall
which have been already indicated, and the ascogenous hyphae or cells are thrust
in between the elements of the wall or lie immediately upon them. The asci
fill the inner space of the perithecium, or at least the largest part of it, excepting the
neck. All the space not occupied by them is filled with branches of the hyphae,
which grow out from the inner layer of the wall toward the median line of the
perithecium. Some of these branches lie between the asci, and are then termed
paraphyses, as in the Discomycetes, and stand in the same relation as regards their
development to the asci as in the Discomycetes, since as parts of the envelope
they are formed before the asci which are afterwards introduced between them.
Others may cover the portion of the perithecium which -is without asci, and
even the canal, and then they are called by Füisting periphyses. In the canal they
are like small closely set hairs of uniform height, which converge from all sides and
are directed obliquely upwards towards the median line of the canal where their
extremities almost touch. Below the inner (lower) entrance of the canal, in the
part of the perithecial cavity where there is no hymenium, their direction and arrange-
ment either remain the same as in the canal, as in Chaetomium and Sordaria
fimiseda, or they point downwards towards the median line and the hymenium
(Fig. 90). Periphyses would appear to be seldom entirely wanting, though this is
sometimes the case, according to Fiiisting, as in some species of Massaria.

It more frequently happens that there are no paraphyses between the asci,
and then the asci alone constitute the hymenium; this is the case in Sordaria,
Melanospora, Claviceps, Epichlo&, Chaetomium (Zopf), Sphaeromphale, and species of
Dermatocarpon, Endocarpon, and Verrucariae (Winter, Füisting). Further details
will be found in special treatises, though the accounts there given must often be
received with caution, for the paraphyses and periphyses and other organs are often
delicate and perishable, or easily overlooked or confounded if the observations are
not conducted with sufficient care, and thus mistakes may often be made, especially
if the material is not in a favourable state and the observer is wanting in experience.

1 Bot. Ztg. 1868, p. 641. 2 Woronin, Beitr. II.

CHAP, V.—COMPARATIVE REVIEW.—ASCOMYCETES.—ELAPHOMYCES. 193

It has already been said that the wall or outer wall of the perithecium is usually
thick, and often firm and hard. That which is enclosed by it is on the contrary
comparatively soft, and has usually great capacity for swelling in water; it comes
out from the firm wall, when a perithecium is opened, like a soft kernel from its shell.
Hence the old expression kernel or nucleus of the perithecium, which included
all the soft parts described above, the asci first of all, and then the paraphyses,
periphyses, hypothecium, and the soft layers of the wall; it had therefore no strict
morphological foundation.

Section LXII. The cleistocarps of the Cleistocarpous Ascomycetes are,
as their name imports, surrounded by a wall, which remains closed and without
an ostiole even when the spores are ripe, and the latter are only released by external
influences which cause the rupture of the wall or by its decay. A great variety
of special forms are included under these general characters. A number of these
are in other respects scarcely anything else than simple pyrenomycetous perithecia
without an ostiole. Among the Chaetomieae which have been carefully studied by Zopf
there is one species, Chaetomium fimeti, which is distinguished from all the species
nearest to it by this want of an ostiole. Others are removed from typical perithecia
by further peculiarities of structure, the Erysipheae, for instance, Eurotium and
Penicillium, which can only be briefly noticed here, as they will have to be described
at greater length in a subsequent page. The sporocarps also of Sphaerophoron
may be mentioned in this connection; their structure is given in Tulasne’, but
their development has yet to be ascertained. All these sporocarps may be
regarded as perithecia with a greater or less amount of deviation or simplification.
The structure, on the other hand, of the compound sporophores of Elaphomyces,
the Tuberaceae, Onygena, and Myriangium is quite different. The early stages
of their development are still too little known, and we can count them among
the sporocarps of the Ascomycetes only because they form asci and on the
ground of some other analogies and resemblances; whether they can rightly be
regarded as homologous with the others must for the present be left undecided.
With this reservation a short description of these forms may be inserted in this
-place, as it will be scarcely possible to recur to them while subsequently relating
the histories of development.

1. Elaphomyces. The sporocarps, which become of the size of a hazel-nut as
they ripen, are round hollow bodies with a perfectly closed wall, usually known as the
peridium, and enclosing the sporiferous tissue or gleda. The wall is some millimetres
in thickness and consists of two firmly connected concentric layers. The inner of
the two, the peridium in Vittadini’s narrower sense, is a dense and massive tissue
of hyphae which are sometimes very thick-walled. The outer layer, the cortex of
Vittadini, is thinner and of a consistence which varies with the species, and may be
smooth, warted, hairy, or spiky. Its structure also varies with the species, and in most
of them has not yet been described with exactness. In Elaphomyces granulatus it is
hard and brittle and thickly beset with warts; the centre of each wart is formed of a
conical group of irregularly shaped cells with their bright yellow walls everywhere
strongly thickened. The bases of these cones are immediately on the inner layer,
and touch each other by their sides. The intervals between the cones and the summits
are occupied by a tissue without interstices composed of many layers concentric to

1 See the figures in his Mém. sur les Lichens.

[4] 0

194 DIVISION II,—COURSE OF DEVELOPMENT OF FUNGI.

the surface of four-sided prismatic cells; the cells in each layer are arranged in rows
which radiate from each cone and meet those which proceed in the same manner from
the neighbouring cones. A section parallel to the surface is consequently made up
of delicate roundish facets composed of radiating rows of cells, each of which has in its
centre a group of thick-walled bright yellow cells.

A loosely felted weft of slender hyphae with elongated segments proceeds on all
sides from the inner surface of the peridium and traverses the gleba; here and there,
especially in younger specimens, the hyphae are more closely combined into larger
plates or strands, but there are no distinctly closed chambers. The gaps in the weft
of slender filaments are everywhere loosely filled with ascogenous hyphae twice or
thrice the thickness of the other hyphae, which are divided into short cells and
are often coiled into knots and bear asci on the extremities of their branches. As
the spores ripen the whole of the ascogenous tissue becomes mucilaginous and
disappears, while the tissue with the slender filaments remains behind as the delicate
‘ capillitium’ between dry masses of spore-dust. On the asci and on the ripening of
the spores, see above, pp. 80 and 97. The spores are large and globular and remarkable
for the enormous thickness of their walls, which may be more than two-thirds of the
semidiameter of the spore; the wall consists chiefly of a thick, gelatinous, stratified,
colourless membrane, covered on the outside with a thin but firm and darkly coloured
episporium. For further details see Tulasne’s Fungi hypogaei and De Bary’s Frucht-
entwicklung der Ascomyceten. The germination of the spores has not been observed.

A few observations only have been made on the early stages of the development
of Elaphomyces.

The youngest sporocarps of E. granulatus which have come under my notice
are small round bodies from 13 to 2 mm. in size in the interior of a compact dirty-
yellow filamentous mycelium. Their outside is covered by a cortical layer of the
same thickness, colour, and warty surface as in full-grown specimens, and consists of
a thin-walled pseudo-parenchyma, the elements of which are often in continuous
connection with the mycelial hyphae. The cortical layer encloses a tissue-mass of
delicate closely woven hyphae, which fills the whole of the interior and shows .the
same structure, but is differently coloured in different parts ; a small central portion
is of a whitish colour, and is surrounded by a dirty-violet layer, between which and
the cortex is a narrow white zone. Later states show that the whitish central mass
becomes the gleba, the rest the peridium. This structure and the relative size of
the separate portions continue unchanged till the sporocarp has reached the size
of a large pea. Larger specimens show the gleba proportionately more enlarged than
the peridium, and the ascogenous hyphae beginning to be developed between the
slender filaments of its original tissue; soon after the gleba forms the chief mass of
the sporocarp, Which grows by degrees to the size of a hazel-nut. While the
peridium consequently increases greatly in circumference, its absolute thickness
increases at the same time or does not diminish. The structure of the inner layer
and especially the thickness of its hyphae remain all this time unchanged ; the cells
also of the cortical layer become only about one half larger than in the first observed
stage, while the warts multiply so that without altering much in size they always
closely cover the surface of the sporocarp, their multiplication being effected by
the splitting of one wart into two or more. All this shows that growth must take
place up to late stages in the development by simultaneous and continued formation
of new cells in all parts. Tulasne’s figures agree with the above account, except in
the statement that young specimens must at first be hollow; the difference arises
perhaps from variations in the species examined. All the facts seem to show that we
have in Elaphomyces a sporocarp with an extremely thick envelope-apparatus and
formed of all the described parts except the ascogenous hyphae. The whole recalls
the sporocarp of Penicillium, as will be seen from the description of that genus below.

2. The sporocarps of the Tuberaceae have the forms of tubers, which either have

CHAP, V.—COMPARATIVE REVIEW.—ASCOMYCETES.---TUBERACEAE. 195 T

an evident basal portion resting on the mycelium, as in Terfezia and Delastria,
or are entirely enveloped when young in the mycelium and are connected with
it, as in Tuber, the mycelium disappearing when the sporocarp is mature and
leaving it naked and detached in the soil. Its surface, if we disregard the frequently
occurring warts and roughnesses, is either smooth and marked only with quite
irregular and so to speak accidental large unevennesses, as in Tuber aestivum,
T.melanosporum, &c. and in Terfezia, or it shows typical pit-like depressions or narrow
deep sinuous furrows, as in Hydnobolites and Genabea.

The sporocarp in its simplest form, as in Hydnobolites, consists of a fleshy tissue
formed of closely woven hyphae, in which numerous asci on the extremities of the
branches are everywhere imbedded ; the outermost layer of tissue only forms a kind
of wall or peridium, a delicate down composed of sterile hyphae.

In a second series of forms we can distinguish between a sterile fundamental mass
and a large number of groups or nests of fertile tissue, i.e. tissue containing asci im-
bedded in it. The fertile tissue is a more or less compact hyphal tissue in which
asci springing from the ends of the branches are distributed irregularly and in large
numbers. This tissue fills the spaces between the fertile groups in the form of broad
bands constituting much the larger part of the sporocarp, as in Genabea, or
comparatively narrow plates which show in section as veins with many fine rami-
fications, as in Terfezia and Delastria. The sporocarp is surrounded on the outside
by a layer of sterile tissue of varying thickness, forming a peridium from which the
veins and bands in the interior take their rise; the hyphae of the fertile groups originate
in the adjacent sterile hyphae.

A third type is represented by the genus Balsamia. The outside of the compound
sporophore is a thick perfectly closed peridium, and the interior is divided by means
of thick plates of tissue springing from the peridium into many narrowly sinuous air-
conducting chambers. The wall of each chamber is covered with a hymenial layer
the elements of which are placed at about a right angle to the wall.

A similar structure is found in the genus Tuber, or at least in several species of that
genus in the young state (T. rufum, T. mesentericum, T. excavatum, &c.'), only the
chambers are very narrow and very much coiled and branched. But nevertheless
hyphae from the adjacent tissue grow into the cavity of the chambers at an early
stage in the development, and fill it quite full with a dense tissue which contains air
in its interstices and is therefore white. At the same time the hymenial layer on the
walls of the chambers increases considerably in thickness, and assumes the character
of a massive irregular tissue which everywhere bears asci. The middle layer of the
wall of the chamber retains its original condition in some species. It is these relation-
ships which produce the characteristic marbled appearance of a section through a ripe
or ripening truffle (Fig. 91), in which two kinds of branched veins run through a
dark-coloured fundamental mass, the fertile tissue; the one kind dark-coloured and
therefore less striking to the sight, which answer to the walls of the chambers and
contain no air (venae lymphaticae, veines aquiféres of Tulasne, venae internae of
Vittadini), the other white and conveying air (veines aériféres, venae externae). The
former always originate in the inner surface df the peridium. The latter and probably
the previous cavities, which they are formed to fill, extend at certain points to the
outer surface of the peridium, and form a kind of opening there to the outside ; this
takes place either at spots irregularly distributed over the surface, or in such a way
that the veins from all parts unite into a chief trunk with an orifice at a fixed spot
in the circumference. In some species of Tuber, T. dryophilum, for instance, and
T. rapaeodorum, air-veins only can be distinguished i in the fundamental mass, which
is traversed uniformly in all parts by asci; this is the case at least in all the states of
development in which they are at present known.

' Tulasne, Fungi hypog. tt. XVII, XVIII.
02

196 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

With respect to the more minute anatomical structure of the Tuberaceae, it may be
further added, that the peripheral layer, known as the peridium, is usually a stout,
thick mass of pseudo-parenchymatous tissue. The outer cell-layers are in most cases
furnished with thickened walls corresponding in colour to the surface, which varies in
shade from brown to black; in a few cases they are thin-walled and have their surface
covered with spreading hairs, as in Tuber rapaeodorum, &c. Except in Stephensia,
in which the layers of the peridium are distinctly separated from each other, the outer
cell-layers pass gradually into the inner and these in like manner into the sterile veins
and bands which spread between the fertile tissue, and which either show the same
pseudo-parenchymatous structure as the peridium (Genabea) or, as in most cases, have
their hyphae disposed in a course which follows that of the veins. Here too ascogenous
hyphae appear in the tissue known as the fertile tissue interwoven with but strictly
distinct from other hyphae which may be termed paraphyses. Moreover it often occurs, .
both in Tuber and Elaphomyces, that a young ascus is placed on a knee of the hypha
which bears it in such a manner that it seems to be borne on two small stalks, some-
what as in Eremascus which will be described below. Tulasne has given representations
of this phenomenon, and Dr. Errera has recently called my attention to it. It may at

Vig

i

FIG. 91. Tuber rufum. asmall specimen divided in half in reflected light: the white veins 7 contain air, the dark ones v
fluid, / the bymenial tissue. 4a thinner section through a young specimen in transmitted light ; lettering as in a, light and dark
of the veins d. «magn. 5 times, 5 ı5 times,

least be a question whether the development of the ascus in these cases is the same or
similar to that of the ascus in Eremascus ; the whole subject requires investigation.

The genera Hydnocystis, Hydnotria, and Genea are not noticed here because a
full consideration of them would lead us too far into descriptive details, and we must
be satisfied with remarking that they are intermediate in their whole structure between
Tuberaceae and typical Discomycetes, especially the Pezizae; they are evidently
closely related to both groups.

We are indebted to Tulasne for the little that we know of the origin of the sporo-
carps in Tuber, and from this they would appear, as has been already stated, to be
formed inside a mycelial weft. The different regions and tissues are differentiated in
them while they are still quite young ; the surface of specimens of Tuber mesentericum
of the size of hemp-seed has the same structure and the same black colour as in those
which are fully grown. Very little more is known than this. We shall have to wait for a
complete knowledge of the history of development in these subterranean plants till we
have succeeded in cultivating them.

3. Onygena corvina, A. S. grows on the feathers of birds of prey and the
mycelium which spreads in them produces stalked spherical sporocarps. The stalk is.
7-10 mm. in length and about 1 mm. in thickness, and consists of longitudinally parallel

CHAPTER V.—COMPARATIVE REVIEW.—ASCOMPCETES. 197

hyphae closely united together. It bears at its apex the spherical spore-receptacle
which is about 2 mm. in diameter and has its dense hyphal weft differentiated into a
wall or peridium composed of many layers of an unevenly floccose loose pseudo-
parenchyma, and a spore-forming gleba within the peridium. The general form of the
gleba is that of a flattened sphere; it consists of closely interwoven and very copiously
branched hyphae, which produce everywhere countless asci in dense tufts on the
extremities of their branches. The asci are comparatively small ovoid bodies
containing each eight delicate ellipsoid spores, which are released when ripe by the
disappearance of the membrane of the ascus. When the entire mass of spores is ripe, the
whole structure dries up, the peridium opens by a circular fissure and becomes detached
like a cap, and the cinnamon-coloured spores are scattered like dust from the flocculent
remains of the ascogenous hyphae. Onygena equina, P. a more robust form has,
according to Tulasne, a precisely similar structure.

4. Myriangium Durieui grows on the rind of trees and forms a large, flat, black
thallus from one to a few millimetres in size composed of a tolerably uniform narrow-
celled pseudo-parenchyma with brown cell-walls. The sporocarps are protuberances on
the outside of the thallus, and consist, as we know from Millardet’s researches, of a
pseudo-parenchyma similar to that of the thallus, but of finer texture, between the cells
of which spherical asci are everywhere distributed usually at some distance from
ene another. The sporocarp thus constituted occupies the middle of a round
protuberance of the thallus in the earliest stages that have been examined. It then
grows by constant formation of new cells in a meristematic tissue which lies on its
inner side, the side which is turned to the substratum. From this tissue new layers of
ascogenous parenchyma are thrust one after another towards the outside. In conse-
quence of the pressure thus produced the original tissue of the thallus in this part is rup-
tured, and the exposed ascogenous tissue breaks away as new tissue is pushed forward.
The great capacity for swelling in the membranes of the ripe asci in the older tissue-layers
favours theirremoval. The youngest asci lie near the layer of meristem between the cells
of the pseudo-parenchyma, from which they are chiefly distinguished by their greater
abundance of protoplasm. As they move towards the outside they grow to 8-10 times
their original diameter and produce eight pluricellular compound spores ; the germina-
tion of the spores is as little known as the further details of their development.

ORIGIN OF THE SPOROCARP.

Section LXIII. The first steps in the formation of the sporocarp (fruc-
tification) of the Ascomycetes have up to the present time been closely studied in
comparatively few species; the search for and clear preparation of the first com-
mencements is in most cases difficult from the small size of the objects, and there is
difficulty also in unravelling the hyphal weft. The subject has been investigated in
a certain number of species in all the chief divisions of the group, and important
differences, recurring in all cases in their most essential points, are found to exist even
between species which resemble each other very closely in the more advanced state.
Intermediate forms are found between the several cases which differ extremely from
one another. The whole series may be arranged in the following order.

1. Eremascus albus is the name given by Eidam to a small Mould which may
be cultivated in nutrient solutions, and which has a filiform septate many-celled
mycelium. To form the sporocarp (Fig. 92) two adjoining cells of the mycelium
put out each a lateral branch (a) close by the transverse wall which divides them.
The two branches are from the first in contact with one another; they are exactly
alike, and they grow coiling spirally round one another to a length exceeding the

198 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

transverse diameter of the mycelial hypha 10 times or more (4). Then they cease to
lengthen, are delimited from their parent-hyphae and conjugate at their summits, the
cell-walls disappearing at the point of contact and the two protoplasmic bodies
coalescing into one (c). The place of conjugation then swells into a spherical vesicle,
which is delimited when the protoplasm of the pair of cells has passed into it, and
having thus become an ascus forms 8 spores capable of germination (d-f). The
spores are formed, as far as can be gathered from. Eidam’s somewhat superficial
description, in the manner described in section XIX. No further complications have
been observed in the formation of these sporocarps.

2. Distinct archicarps are formed as branches on the mycelium or on vegetating
hyphae in the thallus singly, or rarely in groups, as in Pyronema and Physma. It
depends on the species whether the archicarp is a single cell or, as is more com-
monly the case, a cell-row, and whether it is spirally coiled or of some other shape.
The whole ascus-apparatus of the sporocarp is derived exclusively from the archi-
carp. In Podosphaera a single ascus borne on a short stalk-cell is formed by
transverse division of the uni-
cellular archicarp; in other species
ascogenous hyphae sprout as

a branches from the .archicarp, or
the cells of the archicarp divide

into ascogenous daughter-cells,

that: is, into daughter-cells which

b sprout out into asci. The archi-

carp takes no part in the forma-
tion of the envelope-apparatus,
that is, of the wall, receptaculum,
excipulum, paraphyses, &c. This
Sie cet he ea ees eee has TS onen. mn the hyphal
matured and the spores formed in it. After Eidam. Magn. goo times. branches which arise in the neigh-
bourhood of the archicarp, usually
at its base, and grow round the ascus-apparatus in a way which is determined by
the species. From this specific ascogenous function the archicarp may in this case
be termed an ascogonium. It has also been called a carpogonium. Of cleistocärpous
and pyrenocarpous forms the Erysipheae, Eurotium, Penicillium, Sordaria
(Hypocopra), and Melanospora parasitica belong to this section; of gymno-
carpous and discocarpous forms Gymonoascus, Pyronema, Ascobolus, and the
Collemaceae which were examined by Stahl (Collema, Synechoblastus, Leptogium,
Physma, &c.).

In a number of the species of this division an antheridial branch makes its
appearance in characteristic form in connection with the archicarp before the com-
mencement of the formation of asci. This is the case especially with Pyronema,
the Erysipheae, Hypocopra, Gymnoascus, and Eurotium. In Pyronema, before further
development begins, conjugation, the union of the two protoplasmic bodies into one,
takes place between antheridial branch and archicarp, by means of a special appa-
ratus, belonging to the archicarp, the /richogyne, and the same thing happens in
less striking form in Eurotium. In the Collemaceae the antheridial branches are

e

CHAPTER V.—COMPARATIVE REVIEW,.—ASCOMYCETES, 199

formed separately from the archicarps in special layers or receptacles, the
spermogonia, and give off small spore-like cells, the spermatia, by abscision. The
spermatia are conveyed to the archicarp and to a special receptive process of it,
the trichogyne, and conjugate with it. These phenomena correspond in part, and,
excepting in some points of detail which will be described further on, to those
observed elsewhere in distinct sexual organs and processes, and without them the
sporocarp is not developed. The organs here described in the Ascomycetes are
therefore to be regarded in the above cases as sexual organs, the archicarps as the
female, the antheridial branches or spermatia as the male organs.

In the Erysipheae, Penicillium, Sordaria, and Gymnoascus conjugation has not
been observed, but the union of the two kinds of organs is as firm as it is invariable.
Their sexual function therefore has not been certainly proved, but it may be
assumed to be highly probable.

The antheridial branches are less constant and less distinct in Ascobolus and
Melanospora. According to present observations they are not to be clearly dis-
tinguished from the first envelope-filaments that grow round the archicarp; their
sexual function must therefore be considered to be undetermined. The question of
the homologies is not hereby prejudged, as will be explained in section LXVI.

3. An archicarp is formed in the compact thallus of Polystigma rubrum
and P. fulvum very similar to that of Collema, and in this case also the archicarp
alone produces the ascogenous hyphae at a later period. Spermogonia and spermatia
are likewise present, but the union of the latter with the archicarp has not been cer-
tainly observed, perhaps owing to their extreme delicacy. Moreover the archicarp
here makes its appearance inside a delicate (pseudo-parenchymatous) hyphal coil pro-
duced at first as a new formation in the thallus, which may be termed the primordium of
the sporocarp, and from it the envelope-apparatus of the sporocarp is subsequently
developed under conditions of new formation andresorption. The archicarp is a long,
coiled row of many cells. In this respect it is like the archicarp of the Collemaceae,
and one extremity of it projects as in that group in the form of a trichogyne above
the surface of the thallus, while the lower coils are concealed in the primordium. Before
the formation of asci commences, these coils are found to be divided into portions
containing from one to several cells and distributed in the future hypothecium, and
from here they put out the ascogenous hyphae in the form of branches; but the
portion which protrudes as the trichogyne perishes without taking any direct part
in the formation of asci. All these phenomena are exactly similar to those observed
in the Collemaceae, as will appear from the special description of a subsequent page,
with the exception of the union of the spermatia and the presence of the primordium
from the first concealing the archicarp, neither of which has yet been ascertained.

4. The processes observed in Xylaria again are similar to those in Poly-
stigma. First the appearance of a delicate primordial hyphal coil in the thallus;
then inside that of a coiled row of large cells similar to the archicarp of Polystigma
(named by Füisting Woronin’s hypha); finally of cell-groups distributed in the
hypothecium from which the asci sprout, while Woronin’s hypha is to a great
extent at least disorganised and disappears. But a piece of Woronin’s hypha
projecting from the primordium, a trichogyne, has not been observed, and there-
fore no visits of spermatia to it; nor is there any proof of genetic connection

200 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

between the ascogenous cells distributed in the hypothecium and Woronin’s hypha.
Considering the difficulty of getting at the young states of these sporocarps
the data before us leave it open to possibility that both Polystigma and Xylaria
do really behave like Collema, only certain initial and intermediate states being
at present unknown, and that we shall at length discover organs in Xylaria equi-
valent to spermatia. But if what we at present know is the full account of the
matter, then Xylaria is distinguished from Polystigma, and of course still more
from all the forms mentioned in number 2, by the fact that the ascogenous cells
and hyphae do not spring from a distinct archicarp, but, like the paraphyses,
from parts of the primordium, while the archicarp, unmistakeably present in form
as Woronin’s hypha, perishes without taking part morphologically in the formation
of asci.

5. The difference from the first case is still more distinct in certain dis-
cocarpous Lichen-fungi which have been examined by Krabbe (Sphyridium,
Baeomyces, Cladonia), in Sclerotinia and in a number of Pyrenomycetes. ,

Ascogenous and envelope-hyphae are everywhere inserted between one another
and are closely interwoven in the hypothecium of the long-stalked cup of Sclerotinia
Sclerotiorum, but a direct genetic connection, an origin of the two from a common
source, can nowhere be shown; the lowest extremities of both pass into the uniform
sterile tissue which ascends from the stalk. It is nevertheless highly probable that
the two kinds of elements have a separate origin from the commencement of the
formation of the cup, for small round coils of very delicate hyphae are formed
in the sclerotium beneath the rind before the cup emerges from it. The commence-
ment of a cup always rises from above a coil of this kind as a comparatively thick
bundle of hyphae, the innermost of which are branches of the hyphae of the coil, while -
the much more numerous peripheral hyphae originate in the surrounding tissue of the
sclerotium. It is probable that the latter represent the envelope-apparatus, and those
from the coil the ascogenous portion of the cup, and that the coil therefore
is a kind of ascogonium. But a distinct proof of this has never been forthcoming,
because, as the stalk elongates, it is no longer possible to show a morphological
distinction between the two elements and by this means to establish the connection
between the later ascogenous hyphae and their: supposed primordia. Neither anthe-
ridial branches nor spermatia were observed during these developments.

In the Lichen-fungi mentioned above, the ascogenous hyphae may be seen,
according to Krabbe, distinctly marked between the hyphae of the envelope-
apparatus at a very early stage in the development of the sporocarp. But no
initial organ has been observed from which they originated, and it must be presumed
that they both have a common origin in the hyphae of the vegetative thallus or of
the primordium of the sporocarp, and without the co-operation of spermatia or
antheridia.

In the Pyrenomycetes, Claviceps, Epichloe, Pleospora, and perhaps also
Nectria, no co-operation of the above-named organs has been observed, and no
distinct ascogonium. The young perithecium, as at present known, is a body
consisting of similar hyphae or parenchymatous cells, and its elements are gradually
fashioned and differentiated into the parts of the perithecium ; in this process a cell-
group occupying the position of the hypothecium undertakes the formation of the asci,

CHAP. V.—COMPARATIVE REVIEW.—-ASCOMYCETES.—ERYSIPHEAE. 201

and in Pleospora and Nectria the paraphyses are even formed from the same group.
Hartig’s conjecture with regard to Nectria may certainly hold good of Claviceps and
also of Epichloe, that special ascogenous initial organs are really present on the
very young stroma, but up to the present time have been overlooked; as regards
Pleospora we have only Bauke’s somewhat imperfect preliminary communication.
With the accounts at present before us our knowledge is limited to the alleged
mode of differentiation. If we choose to speak of ascogonium or archicarp in
these genera, we must apply the term only to the initial organs which are late in
forming and not very distinct in their differentiation. Van Tieghem’s discomycetous
genus Ascodesmis would belong to this series, if that writer’s not very complete
account of it is correct.

We now proceed to give the details which are necessary for the full under-
standing of what has been said above, and to add some supplementary observations:
The arrangement of the material is for perspicuity’s sake somewhat different from
that adopted in the foregoing account.

FIG. 93. Podosphaera Castagnei on Ti D of the sporocarp. Stages of the development according to the
letters Z—N. o superior, # inferior mycelial filament, a antheridial branch, g archicarp. In G the envelope is beginning to form, in 4

the outer wall is Ka young P quite N a similar one in optical longitudinal section; s an ascus, 7 the
outer wall, 7 the cells of the inner wall formed from the outer. Magn. 390 times.

Section LXIV. 1. Erysipheae (Fig. 93; see also Fig. 107). The mycelium
of these epiphytic parasites is composed of branched septate hyphae which spread
over the surface of the host, being attached to its epidermis by the haustoria
described in section V, and frequently touch and cross one another. The formation
of a sporocarp begins at the point of contact or crossing of two branches. The
process is of the simplest kind in Podosphaera. Two branches put out short
protuberances at the same time, which rise erect from the surface of the epidermis
and are soon delimited by a transverse wall. The one which proceeds from the
lower of the two branches where they cross takes the form of an elongated ellipsoid
cell, 2-3 times the length of the transverse diameter of the parent-branch, and is
the archicarp. The other, the antheridial branch, remains cylindrical in shape,
being of the same breadth as the mycelial hypha from which it, springs or a little
narrower; it is always closely applied to the archicarp, and its upper extremity

202 DIVISION IlL—-COURSE OF DEVELOPMENT OF FUNGI.

bends over and covers the apex of the archicarp, and it is presently delimited by a
transverse wall, forming a short nearly isodiametric cell, the ‘antheridium,’ which is
borne on the lower part of the branch as on its stalk. The archicarp now developes
into the sporocarp, being usually divided by a transverse wall into two cells, an upper
which becomes the solitary ascus and subsequently produces eight spores, and a lower
which as a stalk-cell bears the ascus. Tulasne has found two asci in a sporocarp
as a very rare and individual exception; they were probably caused by the formation
of ‘two transverse divisions in the archicarp-cell. The envelope-apparatus also
begins to be formed at the same time as the ascus. From 7-9 tubular outgrowths
appear close round the base of the archicarp on the hyphae which bear it and
the antheridial branch, and grow up round it and in close contact with it and in
close lateral contact with one another and with the antheridial branch, till they all
meet together above its apex. Each tube then divides by one or two transverse walls,
so that the incipient sporocarp is surrounded by an envelope formed of a single
layer of many cells. These cells then increase in size in the surface-direction, their
walls thicken by degrees and assume a dark brown colour, and they thus form the
outer wall of the sporocarp. During this time they form no further divisions, but
those nearest the substratum send out rhizoid branches which spread over the
substratum ; and in some, but not all, species some of the cells at the apex of the
sporocarp form a number of hairs with delicate ramifications which are described
under the name of afpendiculae. Branches shoot out at an early period from the
inner surface of the cells of the outer wall, which insinuate themselves between it and
the growing archicarp, and ramify and develope into a dense parenchyma-like weft
without interstices formed of two or three or more layers of cells according to the
species; this weft has been termed the zzmer wall of the sporocarp and compared
from its origin and arrangement with the paraphyses of more highly differentiated
sporocarps. With these formations the sporocarp in its envelope is complete in
all its parts, and they are followed by further considerable increase in size only,
which in the end chiefly affects the ascus and leads to a partial displacement of
the cells of the inner wall. The antheridial branch separates from the archicarp
when the branches begin to be formed from the inner wall; it takes part with less
increase in size of its parts and less considerable change of shape in the formation
of the outer wall, between the other cells of which it remains laterally enclosed.

The development of the sporocarp of the species of Erysiphe, under which
genus I include all the Erysipheae which do not belong to Podosphaera, agrees with
the above description except in certain points, the chief of which only will be
pointed out in this place; the reader is referred for further details to the account
given in another work’. The archicarp has the form of an elongated club-
shaped cell, curved spirally round a hooked antheridial branch. The two organs
are surrounded and enclosed by the tubes of the envelope, which give rise, as in
Podosphaera, to the outer wall of the sporocarp and to the inner wall which is
much more largely developed in these species. The antheridial branch enclosed in
the inner wall soon disappears from observation, The archicarp on the other
hand, lying in the basal portion of the sporocarp, grows into a curved tube and

1 Beitr. z. Morph. u. Phys. d. Pilze, III.

CHAPTER V.—COMPARATIVE REVIEW.—ASCOMYCETES.—EUROTIUM. 203

divides by transverse walls into a row of several cells, from which a number of
broadly club-shaped erect asci are formed by each cell of the row growing out
directly into an ascus, or putting out a few short branches which terminate in asci
and are therefore ascogenous.

In both Erysiphe and Podosphaera the formation of the envelope is at first in
advance of that of the asci, and is nearly finished when the asci or the cells which
produce them are still quite small; and it is not till the last stage of the development
that the growth of the asci advances, chiefly at the expense of the tissue immediately

FIG. 94. Eurotium repens. A branch of the mycelium with a gonidiophore c and young archicarps as: sf sterig-
mata. J spirally twisted archicarp 2s with the antheridial-branch and an pe-branch. C older specii with a
larger number of lope-b hes g1 ing round the icarp ; # antheridial branch. D young sporocarps seen from.
without. £ and F other young sp ps in optical longitudinal section. In £ the inner wall is beginning to be formed ;
w the outer wall, / the inner wall-cells and the cells filling the space between the ascogonium and the wall. as the
ascogonium. G ascus with spores. # ripe of E. Aspergili le isolated. 4 magn. 190 times, the rest
of the figures 600 times.

surrounding it. The spores are in most cases formed as soon as the asci have
reached their full size; but in some species, as Erysiphe Galeopsidis and E. graminis,
(Wolff), there is a pause in the development before the formation of the spores, and
further progress only takes place under favourable conditions of temperature and
moisture after a resting period of some duration which happens to fall in the winter-
time; the protoplasm of the tissue of the inner wall is evidently employed to form
the spores.

2. The archicarp of Eurotium (Fig. 94) is produced by the gradual basi-
petal coiling of the extremity of the upper end of a branch of the mycelium into

204 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

the shape of a hollow spiral with four or five turns which lie close to one another.
The spiral is divided by transverse walls into about as many cells as there are turns.
Then two or three slender branchlets grow from the lowest turn in the direction of
the apex, and are closely applied to the surface of the spiral; one of these gets in
advance of the rest and is the first to reach the apex; there it lays its upper
extremity on that of the spiral filament, and, if we may trust our observations,
the two filaments conjugate, that is, their protoplasmic bodies unite by the dis-
appearance of the intervening membranes. Sometimes the branch which anticipates
the rest is seen to grow up inside the spiral, and then the conjugation cannot be so
certainly ascertained; from its behaviour it must be regarded as the antheridial
branch. When it has reached the apex of the spiral it is followed by the rest, and
now all of them put out new branches which become so interlaced and divided by
transverse walls that the spiral is soon covered by a compact layer of isodiametric
cells. The lowest turn of the spiral itself participates in the formation of this layer,
which surrounds the rest of the spiral, the ascogonium-hypha, as the perfectly closed
outer wall of the globular sporocarp. The cells of the outer wall do not divide '
again; but while the sporocarp increases considerably in volume they grow in the
direction of the surface into a tabular form, and secrete on their outer membrane,
which continues thin and colourless, a golden-yellow substance readily soluble in
alcohol in the form of a thick brittle pellicle. Branches shoot out, as in Erysiphe,
from the inner surface of the cells of the outer wall, as soon as these have united,
and ramify and become interlaced and soon form an inner wall of many layers,
while fresh branches from them push in between the loosening turns of the spiral,
and fill the space between it and the outer wall with a tissue composed of thin-walled
cells rich in protoplasm and without interstices. The growth of this tissue causes
the sporocarp at first to increase in volume in every direction and constantly forces
the coils of the spiral ascogonium further apart. When it has reached a certain
point, the spiral begins to put out numerous branches, the ascogenous hyphae, which
thrust themselves in between the inner wall-cells in every direction, and replace
them, and the many extremities of their numerous ramifications become ovoid
eight-spored asci. The continuity of the ascogenous hyphae is more and more lost
as the asci are formed, so that as the spores begin to ripen the outer wall encloses
only asci and the remains of the hyphae and the cells of the inner wall, and at
length the walls of the asci themselves disappear and the sporocarp contains scarcely
anything but ripe spores.

3. According to Brefeld’s researches, the development of the sporocarps of
Penicillium glaucum also begins with the appearance of a spirally twisted hyphal
‘branch. But here we find in the first stages that are open to observation two similar
branchlets surrounded by felted mycelium, which always arise close to one another
and are spirally twisted round one another in one or two turns; whether they are
morphologically and physiologically of equal or unequal value cannot be directly
determined, and the further development gives no certain information on this point,
so that we can only speak of a distinction between archicarp and antheridial
branch of like form with it from the analogy of the otherwise nearly related Eurotium,
Then from the spirally twisted’ body—whether from one only of its component
parts or from both is not ascertained—short ascogenous hyphae grow out as branches

„

CHAPTER V.—COMPARATIVE REVIEW.—ASCOMYCETES.—PENICILLIUM. 205

in every direction, and at the same time numerous branches begin to be formed on
the neighbouring mycelial hyphae which grow rapidly round the others, and inclose
them in a compact envelope composed of from 8-16 layers of cells which leave no
interstices. The elements of this enveloping weft thrust themselves everywhere in
between the ascogenous hyphal branches; in their early states they are much
narrower than these and therefore easily distinguished from them in section. The
spherical sporocarp which in this state is about 0.05-0.09 mm. in size now
increases to an average size of o.5 mm. and more, and this increase is chiefly due to
the enlargement of the cells of the envelope. The great mass of the inner substance
is the part most strongly affected, and its cells become irregularly polyhedral and
colourless, and are provided with much thickened pitted cellulose-membrane and
hyaline cell-contents which turn dark yellow with iodine. The membranes of the cells
of two or three peripheral layers become yellowish brown in colour and form a thick
persistent outer wall, while a few layers on the outside do not share in the thickening:
and are cast off when the sporocarp is ripe. With the commencement of these
changes the ascogenous hyphae elongate and force themselves in between the growing
tissue of the envelope in irregular courses in every direction. In doing this they do
not appear to form many new branches or to increase much in breadth, and the latter
is the case also with the cell-layers of the envelope which are in contact with them.
In sections through an older sporocarp we therefore find in the interior in the large-
celled tissue of the envelope ascogenous hyphae cut through in various directions,
transverse, oblique or longitudinal, accompanied by small-celléd tissue. The cell-walls
of these ‘ascogenous hyphae also become thickened, and when this thickening has
reached a certain point in them and in the envelope, there is a pause in the develop-
ment, a resting condition. This lasts 7-8 weeks, if the sporocarp is placed as
soon as it is ripe in moist surroundings which are favourable to further development ;
but the resting state cannot last much longer, according to Brefeld’s observations,
if the surroundings are dry, for dry sporocarps 3-4 months old proved incapable _
of further development. If the sporocarps are placed within the time stated on
a moist substratum in a suitable temperature, they recommence their development;
the ascogenous hyphae begin to branch copiously, the branches grow at the expense
of the colourless tissue of the envelope which is by degrees entirely dissolved, and
again branch, and at length a large number of small eight-spored asci connected
together in rows and resembling those of Eurotium are formed on branches of
the last order. There only remains at last of the whole sporocarp the pores and
the brownish yellow outer wall, which forms a loose envelope round them. Of
the details of these changes which may be obtained from Brefeld, it will be sufficient
to mention here, that the branches formed on the ascogenous hyphae are of two kinds;
comparatively slender ones which penetrate between the cells of the tissue of the
envelope, ramify copiously in it and are evidently used to effect the dissolution of that
tissue and to take up the products of the dissolution, but do not form asci; and
secondly, thicker much curved forms with short branches of their own, from the
ramifications of which the asci are ultimately produced. These facts recall the.
two forms of hyphae in the ripening sporocarp of Elaphomyces (see page 193).
The entering of the sporocarp on a resting period and the change from this to the
formation of asci at the expense of the tissue of the envelope has its analogue in the

206 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

processes described in Erysiphe graminis and E. Galeopsidis, only that there the
resting-time begins after the formation of the asci, and the spores only have to be
formed when vegetation reawakens. Van Tieghem! describes a Penicillium aureum,
which is distinguished from P. glaucum, as regards the processes in question,
by having no resting-period; he asserts, that in this species both the initial branches
which are spirally wound round one another are ascogenous, that is, that they both
send out branches, the last ramifications of which are asci.

The sporocarps of Aspergillus (Sterigmatocystis) niger and A. purpureus
have, according to Van Tieghem ?, essentially the same development and structure as
those of Penicillium ; and Eidam’s new Sterigmatocystis nidulans, a remarkable
plant in many respects, should also find its place here.

4. The sporocarps of Gymnoascus and Ctenomyces which live on animal
excrements usually appear, according to Baranetzky, Eidam, and Van Tieghem,
as small coils of felted tissue crowded together in heaps on the mycelium, the largest
somewhat more than ı mm. high, but most of them of much smaller size. Their
formation commences with the union of two unicellular segments of the mycelial
hyphae, one of which is wound round the other in a close spiral; the two cells arise
close to one another as lateral branches of one hypha, or spring from different
hyphae, or only the one which is wound round the other is a lateral branch and the
other is an intercalary member of a hypha. The member that winds round the other
is an archicarp or ascogonium. It ceases to grow in length when it has formed
a varying number of turns, and sends out branches instead, forming numerous rami-
fications, which are woven together into a coil and have finally at their extremities
round eight-spored asci like those of Eurotium. The member, round which the
ascogonium is coiled, and which, from the analogy of the cases previously described,
must be called the antheridial branch, is cylindrically club-shaped and either coiled
like the other cell or straight, and can no longer be distinguished by direct observation
when it has undergone a moderate increase in size and become divided by a few
transverse walls. It is not till the ascogonium begins to send out branches that the
young sporocarp becomes loosely enveloped by a number of hyphal branches, which
spring partly from the base of the ascogonium itself partly from adjacent branches of
the mycelium, and have their membranes thickened and coloured yellow or brick-red ;
the peculiar antler-like ramifications of these filaments loosely intertwined form
a lattice-like envelope composed of several layers round the ascogenous coil as
it advances to maturity. Rhizoid branches also spread over the substratum.

5. The sporocarps of the species of Ascobolus (Fig. 95) when fully matured
have the typical discomycetous form. They have the form of a broad short cone,
the obtuse point of which is seated upon the filamentous mycelium while the broad
basal surface is covered by the hymenium. Their development would appear to be
alike in all the species; the following account of it refers especially to Janczewski’s
exact observation of the best-known species A. furfuraceus. The development begins
with the appearance of an archicarp in the form of a comparatively thick arched
lateral branch from a mycelial hypha; this branch becomes by successive divisions

? Van Tieghem in Bull. Soc. Bot. de France, XXIV (1871), p. 157.
* Loc. cit. pp. 96, 203.

CHAPTER V.-—COMPARATIVE REVIEW.—ASCOMPCETES.—ASCOBOLUS. 207

a series of simple apparently similar cells rich in protoplasm which grow to be about
as long as broad, and then a preliminary cessation of this growth takes place. Slender
branches which spring from the mycelium near the archicarp, and also branch.
themselves, now grow in the direction of the archicarp and apply themselves and
their branches closely to its free extremity (Fig. 95 J). They behave in this respect
like the antheridial branches of Eurotium and Erysiphe and may therefore receive the
same name. Their contact with the archicarp is followed at once by the formation
of a large number of fresh branches on the hyphae which produced them and on
adjacent mycelial hyphae, and all these later branches grow closely interlaced round
the archicarp and the first antheridial branches, which from this time cease to be
distinguishable. The archicarp is thus at once inclosed in a compact hyphal coil,
the envelope, which then grows considerably, partly by the introduction of new hyphal
branches partly by the increase in size of those previously formed, the cells of which
become vesicular and for the most part
continue united together into a dense
pseudo-parenchyma. A fewperipheral layers
of these cells form a thick-walled rind,
which is yellow in Ascobolus furfuraceus
from the colour of the membranes but is
differently coloured in other species, and
which sends rhizoid-hyphae into the sub-
stratum at the points of contact, while in
many species, but not in A. furfuraceus, it
produces spreading hairs of peculiar form
and arrangement, With all these changes
the sporocarp assumes a spherical shape,
and the course and direction of its growth
are such that the archicarp remains in-
closed in the dasal portion of the sphere
where it rests on the substratum. The in 3. (ee avec s archleam.

‘ a ith th hyphae s spreading in the sub-hy
formation of paraphyses begins at the same ayer ana me asci a dark, Zantheridial branch, 47 tissue

time as the differentiation of the rind in grammalcalyr ae
the opposite apzcal region, and their first

beginnings appear as branches from a zone of narrow cells still rich in protoplasm
in the tissue of the envelope, /he subhymenial zone, which passes across the apical
region beneath the rind. The paraphyses are formed as slender hyphal out-growths
in this region; each of them can send out new and similar branches of more than
one order near its point of origin. But the ends of the branches of every order grow
into slender long-celled filaments which constitute the paraphyses, and converging at
first have all a direction from the subhymenial zone towards the apical region of the
rind and end below it. In proportion as they elongate and increase in number
by the introduction of new branches from the subhymenial region and whilst the
surrounding parts follow these processes of growth, the space between the rind and
the subhymenial layer grows broader, but is always being filled up by the paraphyses
which are arranged close beside one another as the first commencement of the Aymenium.
It may be observed here by anticipation that the growth of the hymenium continues

208 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

longer in the surface-direction, while the rind covering it does not grow correspond-
ingly, and the rind is therefore ruptured above the hymenium, which is thus exposed
as a discus.

Up to the time of the inception of the hymenium beneath the rind no
changes of. importance take place in the ascogonium. But now all its cells except
one are seen to become thick-walled and poor in protoplasm, and in this state they
continue permanently; but that one cell, the third or fourth uppermost cell, becomes the
initial cellof the formation of asci, the ascogenous cell. It is full of protoplasm and
swells considerably, and then sends out twelve or more strong cylindrical branches from.
its free outer surface. These are the ascus-forming branches, the ascogenous hyphae,
and they thrust themselves in between the elements of the tissue of the envelope as they:
grow in the direction of the subhymenial layer, into which they send their many branches
and spread abroad between the points of insertion of the paraphyses. Finally the
asci appear as lateral branches of the last order on these subhymenial spreading
hyphae, which, as has been already said, grow between the paraphyses and in the same
direction with them towards the outer surface of the hymenium. The long-continued
successive formation and introduction of new asci at all points is the chief cause at:
least of the surface-enlargement mentioned above, and of the exposure and often even
of the convexity outwards of the hymenium. Janczewski’s observations have been
confirmed in the case of several species by Borzi, who has also described an allied
form, a species of Ryparobius, in which every shoot from the ascogenous cell becomes
an ascus directly. Borzi’s view respecting the fertilisation of the archicarp is not
supported by any other case.

6. The development of the sporocarp of Pyronema confluens (Peziza, P.) was
described by myself, but imperfectly, in 1863. Tulasne then added something to my
statements. Kihlman’s recent examination of the species gives the following results
(Figs. 96-99). The Fungus spreads the stout filaments of its mycelium over wide.
spaces of ground, especially where charcoal has been made or fires have burned.:
The inception of the young sporocarp is preceded by the formation of groups of
obliquely erect curved branches, which in their turn put forth many branchlets. Some’
of these, usually two in each group, swell strongly and form a few short bifurcations,
which grow in a direction vertical to the substratum and then cease their longi-.
tudinal growth. The bifurcations form together an erect loose tuft or rosette (Figs.
96, 97 A), and some of them terminate in a short roundish cylindrical cell which
remains sterile. The extremities of others become either archicarps or antheridia
(Fig. 97 A,2). The former are broadly. club-shaped bodies consisting of a much
inflated and usually somewhat curved cell, densely. filled with protoplasm and borne.
on one or two disk-shaped stalk-cells; the antheridia are the club-shaped terminal.
cells of the branches of the bifurcations, about the same height, but only half as broad
as the archicarps. Several, at least two or three, organs.of both kinds are present in.
each rosette, and no other relations than those stated between the points of origin of
each pair of dissimilar organs have ever been observed.. When the two kinds of organs:
have reached the shape and length which have been described, each archicarp puts out:
a broad protuberance near its apex, which grows rapidly into a blunt cylindrical tube:
filled full with protoplasm ; and the tube becoming bent like a bow in a plane differently:
disposed in different individuals, grows on towards a neighbouring antheridium, and.

CHAPTER V.—COMPARATIVE REVIEW.—ASCOMYCETES.—PYRONEMA. 209

embraces its apex and presses its obtuse extremity firmly against it. When this has
taken place, seldom before, the tube is delimited by a firm transverse wall from the
inflated portion of the archicarp, and, as soon as the wall is formed, the membrane
in each of the connected organs is dissolved at the point of contact of the tube with
the antheridium, and the protoplasmic bodies of the two organs unite together through
a broad aperture (Fig. 97 2). The bent tube is therefore an organ which affects an

ors
ER

au

BIT:

Des

FIGS. 96—99. Pyronema confluens, Tul

FIG. 96. Rosette of antheridia and icarps on the mycelial fil m; [first beginni of the fil of the lope.
Magn. 190 times.

FIG. 97. A a small rosette of i p ye PS, a ta trichogyne which has not yet entered into
union with @. B from an older rosette; the trichogyne ¢ proceeding from the archicarp c and cut off by a transverse wall is
in open communication with the antheridium a. Ca pair of organs isolated, from a young sporocarp in about the same stage as
Fig. 98; @ antheridium in icati gh ¢ with an i ¢, which is much swollen and has put out branched
ascogenous hyphae from its surface. After Kihlman’s preparations and drawings. Magn. about 300 times.

FIG.98. Young sporocarp in water showing through the cover-glass. The group of antheridia and archicarps is densely
overgrown by hyphae of the envelope which have formed erect paraphyses above; the archicarps appear through the envelope-weft
as large vesicles. Magn. go times.

FIG 99. Median longitudinal section gh a p in the process of maturing. Archicarps and antheridia can no
longer be distinguished, and many asci have been formed between the paraphyses. (See Fig. 39.) Magn. about 45 times.

heridi.

union between the archicarp and the antheridium and, in accordance with the

terminology which is in use in other cases and which will be further considered below,

may be termed a /richogyne. Conjugation is followed by increase in size in the

archicarps, and by the formation of protuberances in a dozen or more places scattered

over the surface of each archicarp, which develope into thick short-celled ascogenous

hyphae (Fig. 97 C). Simultaneously with this, or even before it, copiously branched
[4] P

210 DIVISION II.—TOURSE OF DEVELOPMENT OF FUNGI,

hyphae begin to shoot out from the sterile sister-branches of the archicarp and from
the whole of the rest of the basal region of the rosette to form the envelope-portion
of the sporocarp (Fig. 98), consisting of a receptaculum enclosing the group of
archicarps and antheridia and the hypothecium with the paraphyses, which latter
always rests free on the receptaculum without an enveloping wall. The dis-
tribution of the ascogenous hyphae and asci and the gradual multiplication of the
latter between these elements of the envelope are essentially the same as in Ascobolus.
The paraphyses form at first a conical tuft on the hypothecium, which generally
broadens out into a disk through the introduction of new elements. The receptaculum
becomes a comparatively large thick large-celled pseudo-parenchymatous disk covered
with rhizoids, and between its elements those of the primary rosette are inclosed, and
are at length indistinguishable (Fig. 99). The antheridia continue longest visible and
indeed almost unaltered, being very full of protoplasm, and take no part in the formation
of the envelope.

7. In Sordaria among the Pyrenomycetes especially S. (Hypocopra) fimicola and
in Melanospora parasitica the course of development in the perithecium, according
to Gilkinet’s and Kihlman’s researches, is essentially the same as in Ascobolus, of
course with certain specific differences, and with differences of conformation corre-
sponding to the difference between Discomycetes and Pyrenomycetes. The archicarp
is a spirally coiled cell-row, though in Melanospora it is sometimes almost straight.
Antheridial branches are less plainly seen in Melanospora, or at least are not sharply
distinguished from the incipient filaments of the envelope, which here too grow
close round the archicarp soon after its formation. In Sordaria the growing
archicarp divides by transverse walls into numerous cells, and ascogenous hyphae
sprout from the great majority of these cells; whether any portion of the archicarp
takes no part in their production could not be determined owing to the early gelatinous
disorganisation of the walls of all its cells. In Melanospora only one or two cells in
the middle of the large archicarp become ascogenous, the rest being disorganised
and afterwards partly ejected in this state from the orifice of the young perithecium.
These one or two ascogenous cells develope by successive bipartitions in varying
directions into a parenchymatous body, the many cells of which are full of protoplasm
and subsequently produce the asci. These are arranged in Sordaria nearly parallel
to one another in a thick tuft, in Melanospora they form a nearly spherical body, and
their apices converge towards its middle. In both cases the many-layered pseudo-
parenchymatous wall of the perithecium is formed from the weft of hyphae of the
envelope. It is a spherical body at first closely surrounding the future group of asci
on every side, the neck and the canal of the ostiole being formed in it later. There
are no paraphyses standing between the asci; these are placed separate and beside
each other on a surface of insertion which covers a part of the interior of the sphere.
On the side left free from the paraphyses there is a narrow empty space between the
wall and the ascus-group, but this is soon filled with a large number of closely packed
hyphal branches, which grow into it as perzphyses from the wall, converging radially
till they touch one another. The group of these which is mostly turned away from
the asci then grows vertically towards the wall in the direction of the neck which is
to be, and so on to the outside through a hole in the wall, and thus forms the
commencement of the neck, which may lengthen out considerably, and in Sordaria is

CHAPTER V.—COMPARATIVE REVIEW.—ASCOMYCETES.—COLLEMACEAE. 211

covered on ihe inside with periphyses which converge towards the median line. All
the periphyses, those of the neck as well as those beneath it, converge till their
extremities touch, but without becoming firmly united, so that asci or spores can pass
between them to the outside when theyare mature. In Melanospora parasitica the future
canal of the ostiole is to some extent marked out from the first, for the non-ascogenous
basal cells of the spiral archicarp, that is the cells turned towards the place of insertion,
remain in their place as large vesicles, together forming a strand outside which the
periphyses which converge towards it afterwards spring from the wall. Then the
neck also grows in the direction of the strand outwards at the place of insertion of
the perithecium or archicarp, while the vesicles are ejected as disorganised masses
of mucilage. In Sordaria it would appear that the canal of the ostiole and the neck
are formed on the side diametrically opposite to the place of insertion of the perithe-
cium ; the first simply in consequence of corresponding surface extension of the young
wall, and as an intercellular space which is at once filled with the periphyses; the
formation of the neck has been less exactly studied.

According to Van Tieg-
hem’s observations Chaeto-
mium is nearly related to
the forms which we have
been considering. The con-
clusions of this writer have,
it is true, been stoutly as-
sailed by Zopf, but on the
other hand they have been
recentlyconfirmedbyEidam,
and rightly as far as I can FIG. 100. A, B Gyrophora cylindrica. A a vertical median section through a

spermogonium imbedded in the thallus; o upper, # under rind, » medullary layer of

see. Some particulars are the thallus. 2 portion of a very thin section from the base of the spermogonium; w
: its wall from which proceed sterigmata with rod-like spermatia s, 7 medullary hyphae

still doubtful, and should be fobs sperogoniam, After Tose: magn so 5p tines ChgDy gta,
submitted to further exam-

ination with due reference to the works of these observers. The latter remark will
apply also to Bainier’s short description of some species of Ascotricha examined
by him and ferhaps belonging to this place; I have not been able clearly to
understand his account of them.

8. The development of the apothecia in the Discomycetes which are included
in the group of the Collemaceae is in all points similar, according to Stahl’s
observations, to those which have just been described. But it is preceded by
fertilisation of the archicarp by spermatia formed at a distance from it, and this
causes the fcllowing modifications.

The Collemaceae form a gelatinous Lichen-thallus with lobe-like branches (see
section CXVI. 5). Sections through the thallus show much-branched hyphae loosely
distributed and interwoven in the thick gelatinous membrane-substance; the branches
are also closely united together at certain spots in the fertile thallus in order to form
the receptacles which produce the spermatia, and which were first clearly distinguished
by Tulasne as spermogonia. These organs, of which Fig. 100 below will give some
idea, though taken from other species, are in the mature state small bodies, but visible
to the naked eye, having very much the shape of the flask-shaped perithecium of the

P 2

212 DIVISION II,—-COURSE OF DEVELOPMENT OF FUNGI,

Pyrenomycetes protuberant below and with a short neck; they are sunk in the thallus
but have the free extremity of the neck on a level with the outer surface. The neck
is traversed throughout its length by a canal open at both ends, the canal of egress.
The wall of the inner ventral portion, which is formed of a close weft of hyphae, bears
a hymenium on its inner surface composed of delicate hyphal branches of uniform
height closely packed together, and converging in the direction of a central space
which is free from them and is in open communication with the neck-canal. These
hyphal branches behave like basidia or sterigmata, and abjoint serially and successively
numerous sfermata at their apices in the form of small cylindrical rod-like cells.
The apparently homogeneous protoplasm of the spermatia has a sharply defined
contour, outside of which is a hyaline jelly, which swells and deliquesces in water and
forms probably the outer layers of their membrane. In this gelatinous envelope the
spermatia when abscised lie at first in the central cavity of the spermogonium and
remain there as long as it is kept dry. If the water finds its way in, the jelly swells

FIG. 101. Collema microphyllum. A transverse section through the thallus; % the hyphae, ¢ the Algae (see
section CXVI), a the trichogyne projecting above the surface ofthe thallus; the spirally twisted archicarp which is
imbedded in the thallus terminates in the trichogyne. B a young hicarp drawn ly. C, D
summits of trichogynes with spermatia attached projecting above the surface of the thallus which is shown by the
horizontal lines. After Stahl. 4 magn. 350, the rest 750 times,

and forces them out of the neck on to the surface of the thallus, over.which they are
distributed if there is sufficient moisture, as can be seen by transferring them to a
drop of water on a microscopic slide, where they move in a slow uncertain manner, due
no doubt to the currents in the dissolving jelly.

The formation and discharge of the spermatia usually precede the appearance of
the commencement of the apothecium, as will be noticed again below. These, the
archicarps or carpogonia, are formed in most species of the group, in Collema, for
example, beneath the surface of the thallus, and singly as lateral branches from hyphae
which have nothing else to distinguish them. They are rather broader than the
parent-hyphae and coil up near their point of origin, forming usually two or three narrow
turns of a spiral, and then lengthen at the free extremity into a straight or slightly
curved filament, which grows towards the surface of the thallus and out beyond it into
the open air; here it often forms a narrow flask-shaped expansion and ceases to grow
in length when the portion outside the thallus is about from four to six times as long
as broad (Fig. 101).

CHAPTER V.—COMPARATIVE REVIEW,—ASCOMYCETES.—COLLEMACEAE. 213

The further development shows that the spirally coiled portion of the archicarp
is the ascogonium or place from which the formation of the asci proceeds, while
the elongated part with its point projecting above the surface of the thallus is the /rzcho-
gyne, serving as the receptive-organ in fertilisation and conveying its influence to the
ascogonium. Both parts are divided as they grow by transverse walls into cylindrical
cells, of which there are about twelve in the ascogonium and as many or more in the
trichogyne ; they are all at first thin-walled and filled with a homogeneously hyaline
protoplasm. The formation of archicarps generally takes place under the same
external conditions as the discharge of the spermatia; namely, in the cool, damp,
rainy period of the year. If the spermatia which have reached the surface of the
thallus encounter the top of a new-formed trichogyne they attach themselves firmly
to it often in great numbers, and notwithstanding the difficulty of minutely observing
such small bodies when adhering to the comparatively thick trichogyne, Stahl was
repeatedly able to assure himself that some of them put out a short process by means
of which their protoplasm becomes united with that of the apex of the trichogyne
(Fig. 101 D). The effect of this union with the spermatia is seen in peculiar
changes in the trichogyne, advancing from the apex to the base, and in the asco-
gonium and surrounding parts, and these changes are not observed if no union takes
place between trichogyne and spermatia. The changes are these; the cells of the
trichogyne lose their turgidity and shrink into slender threads; their transverse
walls only maintain their former breadth and at the same time swell strongly in the
direction of the axis of the trichogyne, and thus form knot-like protuberances in the
collapsed cell-row. The cells of the ascogonium continue turgescent, thin-walled, and
rich in protoplasm, and increase in size and number by transverse divisions, Finally
a large number of branches begin to be formed in the neighbourhood of the ascogo-
nium on the adjacent hyphae of the thallus, and these ramifying repeatedly and inter-
twining grow round the outside of the ascogonium and also push in between the turns
of its spiral and force them apart; the ascogonium is thus rapidly inclosed in a mass
of closely coiled filaments, the first-state of the envelope of the fructification. The coil
is at first round and occupies the place in the interior of the thallus in which the
ascogonium inclosed by it was first formed. When it has reached a certain size
(Fig. 102), the hyphae on the side towards the adjoining surface of the thallus send out
branches which again branch repeatedly, and the final ramifications are the first
paraphyses which grow straight towards the surface of the thallus, pushing aside the
tissue of the thallus which stands in their way, and terminate in it. At the same time
the envelope-coil which was originally round increases in breadth in the direction of
the surface of the thallus—chiefly no doubt by centrifugal formation of new hyphal
branches on its lateral margin, so that it assumes the form of a concave disk cutting
the surface of the thallus with its edges; and thus it developes into the ultimately
pseudoparenchymatous excipulum, which continues for some time to increase in.
breadth at the margin which rests on the surface of the thallus. As the development
of the excipulum advances, new paraphyses similar to the first shoot out one after
another from its side towards the surface of the thallus, pushing aside the tissue of

1 The term was introduced by Bornet and Thuret to denote the analogous organs in the
Florideae. See Ann. d. sc. nat. ser. 5, VII, p. 137.

214 DIVISION II,—COURSE OF DEVELOPMENT OF FUNGI.

the thallus which is in their way, till at length the space between the excipulum and
the surface of the thallus is filled by an incipient hymenium consisting of paraphyses
standing side by side with no gaps between them. The ascogonium has meanwhile
at first slowly followed the growth of the excipulum by intercalary growth accompanied
by a loosening of the turns of the spiral. As the development proceeds the asco-
genous hyphae sprout from it, and spread their abundant ramifications through the
zone of origin of the paraphyses, the subhymendal layer, in essentially the same
manner as in Ascobolus, and thrust the asci as branches of the last order one
after another in between the paraphyses (Fig. 102).

The species of Physma also examined by Stahl agree with Collema except
in the following peculiarities. The archicarps here spring from the hyphae which
form the protuberant base of the spermogonia, from four to eight on each spermo-
gonium. The ascogonia are but slightly curved and are inclosed in the hyphal

II]

IN Z
Mie
We -

Il

a

Kt

IN]
|) il ave
We a we i In
SI a a DR ER

au Won MAIN
A Sl. Me
es

| ill i

nO

FIG. 102. Collema anicrophyllum. Median section through a young apothecium imbedded in the thallus; 4 and g as
in Fig. 108, d—c excipulum and hypothecium ; from the latter proceed crowded upright paraphyses, between which asci are
beginning to be formed on the ascogenous hyphae above the hypothecium. After Stahl, Magn. 530 times.

weft of the wall of the spermogonium, and the trichogynes protrude beyond the outer
side. The discharge of the spermatia of a spermogonium coincides as a rule with
the completion of the trichogynes which belong to them, and these become covered
with the spermatia adhering to them. Then paraphyses grow out from the wall
of the spermogonium into its now empty cavity, displacing the sterigmata, and soon
fill it up in the form of a tuft of filaments which converge towards the former orifice
and are so closely packed as to leave no spaces between them. Into the subhymenial
zone, which is thus defined, ascogenous branches shoot out from the archicarps and
push the asci in between the paraphyses; the spermogonium is thus converted into
the apothecium.

Borzi has repeated Stahl’s observations on other species of the Collemaceae with
confirmatory results.

g. Incipient sporocarps or archicarps, of doubtful character and requiring a
fresh examination, have been assigned by Woronin to Sphaeria Lemaneae, Sordaria

CHAPTER V.—COMPARATIVE REVIEW.—ASCOMYCETES,—POLVSTIGMA. 215

fimiseda, Peziza granulata, and P. scutellata, and by Tulasne to P. melanoloma; by
R. Hartig to Rosellinia quercina and Nectria.

ıo, Polystigma rubrum and P. fulvum. The thallus of these Fungi
forms compact disk-shaped stromata in the living tissue of the leaves of species of
Prunus. It forms spermogonia, which resemble those of Collema in structure and
produce curved filiform spermatia. At the same time or soon after, the primordia
of the perithecia make their appearance in its interior. These are small coils
of closely interwoven hyphal filaments, which are perfectly similar in structure
in their early stages and show no manner of differentiation. The individual cells
of the coil are distinguished from those of the thallus by their small dimensions and
especially by turning yellowish brown, not blue (see page g), with solution of iodine.
As the growth of the coil proceeds the cells in its interior assume a more delicate
appearance from diminution in thickness of their walls and become densely
filled with protoplasm. A spirally coiled filament composed of broad and
rather short cells, which comes out very beautifully when coloured with iodine, now
becomes conspicuous among them. Its two or three turns extend through the entire
space of the primordium, which in this stage is usually of an elongate ovoid form.
The extremity of the filament rises above the primordium and passing through the
cells of the mycelium penetrates to the surface of the leaf, where it finds its way
through a stoma into the outer air, and has a perfect likeness to the apex of the
trichogyne in the ascogonium of the Collemaceae as described by Stahl. The point _
is generally accompanied by more slender mycelial hyphae which grow out through
the stoma when the trichogyne has decayed, and form a penicillate tuft of
companion hyphae. Spermatia have been frequently seen to adhere to the summit
of the trichogyne, but in no case has a more intimate connection, especially
conjugation, been proved to take place. After some time the cells of the
trichogyne-filament begin to die away from above downwards and to be no longer
distinguishable in the tissue of the thallus, while the young perithecium enlarges at
the same time throughout, the cells of its outer layers becoming elongated to form the
wall, The remaining portion of the spiral filament, the ascogonium, also enlarges
its cells considerably and now appears as a thick highly refringent strand of cells.
In Polystigma rubrum the young perithecium remains in this state during the winter,
but the development goes on without interruption in P. fulvum, and consists in the up-
ward growth of the envelope in a conical form and the flattening of the basal portion
of the young perithecium, while the inner tissue swells at the same time into a jelly.
The ascogonium lies irregularly distorted on the base of the young perithecium. The
hyphal weft of the base of the perithecium sends in paraphyses between the cells of
the ascogonium in the form of thick cell-rows with walls which readily swell
into a jelly, while the upper part of the wall of the perithecium is covered
with periphyses. The cells also of the ascogonium, all of them apparently,
form protuberances which elongate into slender filaments with abundance of
protoplasm and then branch, and soon become a mass of interlacing threads
amongst the basal tissue of the paraphyses; these are the ascogenous hyphae,
and their last ramifications grow upwards as asci, and as they increase in
size they displace the paraphyses, which are then dissolved. The periphyses also
disappear, and the basal tissue of the asci and paraphyses swells up and can

216 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

no longer be recognised, so that the perithecium in the mature state is broadly
ovoido-conical with an indistinct ostiole. The wall is formed of three or four layers
of not much thickened elongated cells.

Phyllachora Ulmi appears to show similarity to the process here described.

11. The club-shaped stroma of Xylaria polymorpha (Fig. 103) consists in the
young state, according to my earlier observations, of a white medulla surrounded
by a firm black rind. The former is composed of an air-containing tissue of
colourless hyphae; the rind of the portion bearing perithecia consists of small-celled
pseudo-parenchymatous tissue, which is overlaid on the outside by the hymenium
which bears gonidia (see section LX XI) and ultimately disappears. The primordia

FIG. 103. Xylaria polymorpha, A, B, C transverse sections through young stromata with perithecia divided more or
less exactly in half, all three magn. go times. > rind, 2 medullary layer of the stroma. 4, 5 very young perithecium cut
through the middle, 7 a similar one cut through near the median plane, ¢ older perithecia, 2 gonidial layer. 2 perithecium
with the mouth % bursting through the rind. C a nearly fully developed perithecium ; the section passes close to the mouth,
which is fashioned as at g in A, elsewhere through the median plane; / the outer, z the inner wall of the perithecium,
x the large-celled paraphyses filling the centre of the perithecium having entirely displaced the short-lived inner tissue,
A the inner surface of the wall with the insertions of the paraphyses and asci.

of the perithecia (4, #) make their appearance in the form of small spherical bodies
which lie in the medulla close beneath the black rind, and are at once distinguished
from the medullary tissue by containing no air and therefore being transparent.
They are formed of a closely woven mass of slender hyphae, which are much
thinner than the hyphae of the original tissue and must therefore be a new formation
in it. In somewhat older specimens an irregular large-celled coil of tissue is found
lying in the middle of the sphere. The spheres now increase in size in the direction
of the medulla, the shape, structure, and position remaining the same. Then a
dense tuft of straight hyphae, in the shape of a broad truncated cone, shoots forth from
the part which abuts on the rind, and elongates in the direction of the rind, which is

CHAPTER V.—COMPARATIVE REVIEW.—ASCOMFCETES.—XYLARIA. 217

first bulged out a little and then gradually pierced through, so that the extremities
of the hyphae project above the surface (2, z). The young perithecium has
meanwhile become egg-shaped, its broader portion lying in the medulla being
the future basal part, while the narrow end which is wedged into the rind is
the future neck with the ostiole. The canal lined with periphyses is formed
at an early period in the median line of the neck in a way which has not been
exactly ascertained, and the elements at its circumference become thick-walled and
black, and hence the neck is soon surrounded by a black outer wall which is con-
tinuous with the cortex (g). The process of turning black progresses very slowly towards
the base of the perithecium and is only completed when the perithecium is ripe. After
the origin of the neck the basal portion of the perithecium extends itself further
into the medulla. Its circumference is all the time occupied by a layer of slender
firmly woven hyphae running parallel to its surface, and this layer is the outer
wall, which also becomes afterwards thick and black. This encloses a tangled
mass of filaments filling the whole inner space; the component hyphae, with the
exception of the large cells just mentioned, remain delicate and slender and swell
strongly in water. The following is the result of Fisch’s investigation into the further
development.

The peripheral portion of the delicate hyphal weft last-named takes an active
part in the further growth, and developes into the thin-walled hyaline pseudo-
parenchymatous inner wall or subhymenial layer, which is about 6-8 layers of cells in
thickness. The whole of the inner surface of the wall gives rise to slender hyaline
large-celled paraphyses which appear at first singly but are afterwards closely crowded
together and converge towards the middle having walls that can swell gelatinously,
and also to small-celled ascogenous hyphae abundantly supplied with protoplasm,
which stand between the points of insertion of the paraphyses and are everywhere in
connection with the elements of the subhymenial layer. These hyphae do not reach their
full development till the inner space is quite filled with paraphyses, and they develope
at the cost of them. With the beginning of the formation of paraphyses, and in proportion
as it advances, the primordial tissue, or as much of it as has not been expended on
the construction of the inner wall, becomes spongy and gelatinous, and then dissolves
and the paraphyses take its place. The same thing happens also to the coil of large-
celled tissue which was merely alluded to above and must now be noticed again. In
its very early state, in which it was first mentioned above, it may often be easily
recognised as one simple row of comparatively large cylindrical cells very full of
protoplasm and irregularly rolled up together. In some cases it is uncertain whether
it is composed of one or more than one row of cells. It has an exact resemblance,
especially in the first case, to the ascogonium of Polystigma, but with this difference,
that it is always entirely inclosed in the spherical primordium, and does not send out a
trichogyne-process outside it. It takes no direct part in the formation of the asci
but, as the primordium increases in size, its coils are drawn asunder and then separated
into pieces by the intrusion between them of branches of the transitory primordial
hyphal weft. The entire coil remains inclosed in this weft and swells into a jelly and is
dissolved with it; it is rare to see small portions of it taken up by the subhymenial
layer and withdrawn from their inevitable fate. The transverse walls in the cells of the
coil resist the dissolving influences longest, and even swell for a time into highly

218 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI,

refringent plates like those of the trichogyne of Collema; but at length they entirely
disappear, the last remains being still recognisable as the paraphyses begin to form.

From Fiiisting’s! many researches it is more than probable that the development
of the perithecia inside the stroma, not only in all the species of Xylaria and in
Ustulina where I observed it some time ago, but also in the genera Diatrype,
Stictosphaeria, Eutypa, Nummularia, Quaternaria, and Hypoxylon, runs essentially the
same course as has now been described in Xylaria polymorpha, with the exception of
course of specific differences of shape and especially of the formation of the wall and
the orifice. In all cases there appears, especially in the delicate coil of hyphae which
forms the primordium, the row of broad cells irregularly rolled up and full of
protoplasm, which Füisting terms Woronin’s hyph@; in all cases Fitisting observed
the gradual disappearance of these cells without being able to prove a direct connection
between them and the ascogenous hyphae, which sprang finally with the paraphyses from
the wall of the perithecium in similar relations to them of place and time as in Xylaria.
It is true that the views and objects of observers have so far changed since his in-
vestigations that his statements cannot be regarded as certainly infallible, and fresh
examination might not be superfluous.

12. The sporocarps of Sclerotinia Sclerotiorum, the conformation of which
was shortly described on page 52 (see Fig. 106), show, as the cup begins to
‘expand, the first asci between previously formed paraphyses, and new paraphyses
are added one after another with the growth of the margin of the cup, and then more
asci are interposed between them, at first singly, but afterwards in greater num-
bers and crowd out the paraphyses. Asci and paraphyses are of course branches
or the extremities of branches of the hyphae of which the original bundle was com-
posed; but the asci when once found cannot be referred back with the paraphyses to
common parent hyphae ; only hyphae are found, as Brefeld also states *, which terminate
either in paraphyses or in numerous asci; the latter hyphae penetrate deep into the
subhymenial layer. In this layer the ascogenous hyphae cannot be distinguished from
the others, and where their first origin is to be found, remains uncertain. The examina-
tion of the first beginning of the cup in the sclerotium leads to a conjecture on the
subject. Certain bodies are formed in sclerotia, if kept moist, before there is any
external appearance of sporocarps. These bodies, which here too may be termed
primordia (Fig. 104), appear in large numbers in the periphery of the sclero-
tium, either close beneath the black rind or a little further in,-as round trans-
parent objects about 70-100 » in diameter. They consist of a coil of very narrow
tangled hyphal branches with gelatinous membranes; their cavities, which are filled
with protoplasm, appear to run through a homogeneous jelly. They originate iri
single stout medullary hyphae of the sclerotium which are not distinguished from the
rest in any other way ; branches from these hyphae form the coil of filaments, and its
development is accompanied with displacement and gelatinous disorganisation of the
adjacent medullary hyphae. The bundle of hyphae of which a cup is formed always
bursts from the sclerotium above a primordium of this kind (Fig. 105), and consists of
a smaller central portion which branches off directly from the primordium, and a larger

1 Bot. Ztg. 1867. 2 Schimmelpilze, IV.

CHAPTER V.—COMPARATIVE REVIEW.—ASCOMYCETES.—SCLEROTINIA. 219

peripheral mass the elements of which originate in the periphery of the primordium
as branches of the stout medullary hyphae. The small central bundle is short, the
peripheral hyphae are longer in proportion as they are nearer to the circumference,
and, like the periphyses of the Pyrenomycetes, their extremities converge towards the
median line, and thus a narrow depression is formed at the apex of the whole which has
been noticed before on page 52. No other decided difference of structure isto be observed
even at this time between the two kinds of hyphae, and during the subsequent growth

FIG. 104. Sclerotinia Sclerotiorum. Thin ver-
tical section through the periphery of a sclero-

tium which has been kept moist and is ready FIG. 105. Sclerotinia Sclerotiorum. Mediansection through a
to develope; beneath the black rind is the young p which is bursti 'hrough the rind. Magn. 90
primordium of a sporocarp. The dark angular times, butcompleted from higher enlargements.

bodiesare calcium oxalate. Magn 15otimes. See

also Fig. 14.

of the whole body all possibility of distinguishing them ceases. But it is not improbable
that the difference reappears with the formation of the ascus, in other words, that the
hyphae which have proceeded from the primordium are the ascogenous hyphae and
the primordium is therefore an ascogonium, while the envelope-apparatus of the
sporocarp with the paraphyses comes from the peripheral hyphae; and thus the
young sporocarp contains from the first the two elements side by side, though they
are not anatomically different. The original structure
of the primordium is obscured after the emergence of
the sporocarp, but its place usually continues to be
distinctly marked by the brown colour of the walls of
the medullary cells at its circumference; this however
may often ultimately spread to the primordium also.
The number of primordia in a sclerotium is always
much larger than that of the sporocarps which are
matured; many are obliterated by their peripheral cells
turning brown or are destroyed by the emergence of
neighbouring SPUREN FIG. 106. Sclerotinia Sclerotiorum.
Sclerotinia Fuckeliana shows phenomena of a a ps of

development quite similar to those which have been

described; but there is one difference which adds greatly to the difficulty of obser-
vation: the primordia are not formed inside, but on the surface of the sclerotium.
A thin bundle of hyphae from the medullary tissue bursts through the rind and
developes on its outer surface into a dense round coil, the central part of which
is like the primordium of S. Sclerotiorum and is surrounded by the peripheral hyphae

220 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

as a large-celled envelope. The round coil then developes into the at first cylin-
drical sporocarp by the aid of branches from the primordium and from its envelope,
which have the same relation therefore to each other in this respect as the primordium
and medulla in S. Sclerotiorum. The incipient sporocarp is therefore now seated
on the rind of the sclerotium in the same form as the one represented in Fig. 105
beneath it. Meanwhile more branches from the elements of the medulla have
grown through the rind up to the envelope, so that the rind is pierced by a
strand of hyphae as broad as the sporocarp and passing into the envelope, a
condition of things which continues in the form represented in Fig. 19. What-
ever could be observed of the final maturing of the sporocarp is the same as in
S. Sclerotiorum.

13. According to Gibelli’s and Griffini’s researches confirmed by Bauke the
development of the perithecium in Pleospora herbarum differs to some extent from
those described above, the perithecium being formed by differentiation at a late period
of growth of a spherical primordium originally composed of a uniform pseudo-
parenchyma. This arises from one or two adjacent mycelial cells which are converted
into the spherical primordium by active cell-division in every direction. The
initial cell was previously constituted by one, rarely several, hyphal branches, which
show no fixed arrangement and no peculiar changes in their further development.
Then a bundle of slender paraphyses springs from the basdl region into the parenchy-
matous body, displacing and dissolving its original central tissue, and grows on into
the inner space; and after that, in the observed cases after a winter’s rest, the asci
are formed ‘in the middle of the paraphyses as branches from their basal cells;’ the
paraphyses swell into a jelly and disappear as the asci mature.

Similar proceedings are perhaps to be observed in Sphaerella Plantaginis ac-
cording to Sollman’s statements’, but these are not to be relied upon.

14. In Claviceps purpurea, according to Fisch, the formation of the perithecia
begins with the differentiation of a few cells in the periphery of the young capitate end
of the stroma which proceeds from the sclerotium (see page 38 and also section LXV).
Two or three hyphal cells become filled with strongly refractive protoplasm and
begin to form by divisions in all directions a very small roundish or elongate-ellipsoid
cellular body, which is clearly distinguished from the pseudo-parenchyma of the
capitulum by the small size of its cells and the nature of their contents. The mode
of formation of the cavity of the perithecium could not be certainly ascertained ; but
in all probability it is effected by the mutual separation of the cells in the interior,
either by the simple parting of the walls or by dissolution of a cell-layer ; in this way
a cavity would be formed, the roof of which would be the greater portion of the wall
of the perithecium, and its floor become the incipient hymenium. The young peri-
thecium as a whole soon acquires the form of an elongated cone by growth in the direc-
tion of the radius of the capitulum, and this change is accompanied by an elongation
of the whole peripheral cell-layers of the body, thus plainly delimiting the wall of the
perithecium. The point of the young perithecium elongates above into a cone, and
forms a canal which is beset all round from below upwards with periphyses, while small’
protuberances grow out of the upper cell-layers of the young hymenium and lengthen

' Bot. Ztg. 1864, p. 281.

CHAPTER V.—COMPARATIVE REVIEW.—-ASCOMYCETES.—SPHYRIDIUM. 221

and form asci. No paraphyses are formed. The whole process shows great simi-
larity with that described by Bauke in Pleospora.

The formation of the perithecia in the stroma of Epichloé is undoubtedly very like
that of Claviceps; so probably, according to Fisch, is the same process in Cordyceps
(C. militaris, C. ophioglossoides, and C. capitata). The perithecia also of Nectria,
according to Janowitsch’s earlier observations and of Cucurbitaria according to Bauke’s
report, are formed without initial archicarps, antheridia, or spermatia, but simply by late
differentiation of portions of the stroma which were at first uniformly parenchymatous
or consisted of closely woven hyphae; in both genera there is also a dissolution of
the original central pseudo-parenchyma to make the inner cavity and a formation of
paraphyses between the asci. But these older investigations require to be repeated at
the present day. R.Hartig’s account of Nectria mentioned above (page 217) is specially
deserving of attention ; he suspects that the perithecia in N. ditissima.are produced from
archicarps which are formed originally superficially on the stroma under a covering
of gonidia-forming hyphae, and are then inclosed by branches from adjacent hyphae,
and that in conjunction with these latter hyphae they then give rise to the primordial
pseudo-parenchymatous formations from which Janowitsch’s investigation sets out.
The possibility of similar processes is not entirely excluded by the accounts which we
possess in the case also of Epichloé.

15. Van Tieghem gives the name of Ascodesmis to two small Discomycetes
which in the full-grown state look like small Ascoboli and are distinguished by
reticulate thickenings of their spore-membranes. He describes the development
of their apothecia from specimens cultivated on microscope-slides in the following
manner. A slightly bent lateral branch rises from a cell of a filament of the mycelium,
and, after a short increase in length, branches in a pseudo-dichotomous manner ; this
mode of branching is repeated through several orders in planes which intersect each
other alternately, and the successive branches have a similar curvature. At length they
all become woven together into a cushion of compact pseudo-parenchyma, which is
attached on one side to the mycelial filament by a short stalk. Then closely crowded
paraphyses shoot out from the superficial cells on the opposite side, and then the asci
one after another from the same surface and between the paraphyses. We are not
told whether any difference appears between the ascogenous cells and those which
form paraphyses, or if the asci at least which follow one another spring from distinct
ascogenous hyphal branchlets.

16. The apothecia of Sphyridium fungiforme, S. placophyllum and
Cladonia Papillaria consist in the mature state of close-set paraphyses and of asci
inserted between them, and the asci arise from distinct ascogenous hyphae in the
hypothecium. According to Krabbe?! the commencements of these apothecia are
peripheral shoots from the outer surface of the thallus, and the layer of paraphyses
first makes its appearance and afterwards the ascogenous hyphae with the asci. No
trace was observed of a distinct carpogonium or archicarp, as the source of the
ascogenous hyphae, or of any co-operation of spermatia; on the contrary, the
ascogenous hyphae are branches of ‘ordinary’ hyphae, hyphae, that is to say, which
aré not distinguishable from vegetative hyphae and from those which form

1 Bot. Ztg. 1882.

ne

222 DIVISION II,—COURSE OF DEVELOPMENT OF FUNGI.

paraphyses. The sporocarps of Baeomyces roseus, which are very like those
of Sphyridium in shape, first appear as coils of hyphae in the interior and deep
beneath the surface of the thallus, and are there differentiated into layers of
paraphyses and ascogenous hyphae. Subsequently they emerge from the thallus as
long-stalked bodies in consequence of the elongation of their basal portions. But
Krabbe was unable to arrive at any more positive conclusion with respect to the origin
of the ascogenous hyphae than in the case of Sphyridium. According to the same
observer Sphyridium carneum exhibits a curious variation from the genera with
which it has hitherto been associated. Its sporocarps would appear to be only pseudo-
sporocarps, sporocarp-like shoots from the thallus, which form neither paraphyses,
nor asci, nor even spores, only coils of hyphae beneath the surface, in appearance like
the ascogenous hyphae of allied species, but never forming asci.

We learn from Krabbe’s latest ‘ preliminary’ communication that in the Clado-
nieae, except Cladonia Papillaria, the whole of the large body known in descriptions
as podettum, for instance the well-known cup in C. pyxidata and the branching
shrubby form in C. rangiferina, is by its mode of origination an apothecium. It is
formed as a primordial hyphal coil in the interior of a crustaceous or foliaceous thallus
and forces its way through the rind outwards and then arrives by progressive or inter-
calary growth at its final form. The differentiations into ascogenous hyphae, dis-
tinguishable from the rest by turning blue with iodine, and the paraphyses is effected
without a distinct archicarp and virtually in the same way as in the species of
Sphyridium and Cladonia already mentioned; taking place either when the body
is just emerging from the thallus, as in C. decorticata, or not till it has acquired
in separate parts the final cup-like or shrubby form. Ascogenous hyphae and even
asci may in some species revert to the vegetative form} and certain- kinds which
have paraphyses in the normal manner either do not produce perfect asci, or only do’
so exceptionally. We must wait for the author’s more detailed accounts, and we
shall return to the anatomical character of the podetium in section CXVI.

From the agreement found among the sporocarps of the Ascomycetes in the
mature state, it may be considered to be certain that they may all be included as
respects their origin in one or other of the types above described or come very near
them ; which type it should be must be inquired into in each particular case, and
cannot be decided with certainty from the mature condition. The many careful
researches of Schwendener and Fiiisting into the formation of sporocarps in Lichens
may still be adduced in support of this view; these observers failed to account for
the first beginnings only of the ascogenous hyphae which are differentiated at a very
early period. Füisting reports the presence of Woronin’s hypha in the young sporo-
carp of Lecidea formosa, and Stahl! says of Parmelia stellaris and P. pulverulenta
and Endocarpon miniatum: ‘It is not difficult, especially in layers of Parmelia stellaris
with many sporocarps, to find the extremely delicate apex of the trichogyne in
young sporocarps; I succeeded in some successful preparations in showing the
connection between these processes and the ascogonia which were distinguished by
the abundance of their protoplasm.’ Since spermogonia and spermatia'are present
in all these forms, as they are in the Collemeae, it is natural to suppose that there is
a near agreement between them and the Collemeae ; but this is not yet demonstrated.
Fiiisting says that he has not found his Woronin’s hypha in species of Verrucaria,

! Beitr. z. Entw. d. Flechten, p. 41.

CHAPTER V.—COMPARATIVE REVIEW.—ASCOMYCETES. 223

Pyrenula, and Polyblastia, and Krabbe’s results given above make it highly probable
that the processes in the Lichen-fungi with which he was dealing are of a different
kind.

With regard to the rest of the phenomena observed in the sporocarps of the
Lichens of which we are speaking, it may be remarked that apothecia as well as peri-
thecia are not formed on the surface as in Collema and most of Krabbe’s species, but
inside the thallus, as in Xylaria, in the shape of coils of delicate primordial hyphae
which only come to the surface in the course of further development, pushing aside
the tissue of the thallus above them in a manner which varies with the species. In
species of Placodium, Lecanora, Zeora, Callopisma, Lecidea, Blastenia, Bacidia, and
Pannaria, which have been examined and which form apothecia, a dense tuft of slender
branched filaments, growing towards the outside, shoots out at an early period from
the whole of the upper side of the primordial coil which is turned towards the upper
surface of the thallus; these filaments are the first paraphyses. An outermost layer of
similar filaments, open above and of varying thickness in each case, surrounds the tuft
of paraphyses and runs tothe surface of the primordial coil; this layer is the excipulum,
though not exactly in the sense in which that word has been used hitherto in descriptive
Lichenology. The excipulum is either formed at the same time as the first paraphyses,
so that the outermost rows of the tuft become the hyphae of the excipulum, as in
Placodium, Lecanora, Lecidea, &c., or before the paraphyses as in Blastenia ferruginea,
Huds. according to Füisting. While the filaments of the primary tuft of paraphyses
increase in length and form new branches, which insert themselves vertically between
the first ones, and while the excipulum enlarges its surface in every direction by the
formation of new interposed hyphae and grows by the appearance of new elements at
its margin and of new hyphal branches continually behind the margin, which are like
the primary paraphyses and in contact with them on the outside,—while all these
processes are going on simultaneously, the young sporocarp by accession of new
elements increases in height and thickness. The introduction of new branches
continues for some time in the lower portion of the original tuft of paraphyses, and
in such a manner that the filaments which were at first parallel become irregularly
woven together, forming a tissue which cannot be distinguished from the primordial
coil. The formation of new elements is followed directly by increase of size through
expansion of the previous elements. The whole growth is first completed in the
middle of the sporocarp; it continues longest, and often a long time after the
sporocarp has appeared on the surface of the thallus, in the upper margin of the
excipulum and close underneath it, where new constituents are being constantly and
progressively added by apposition. The ascogenous hyphae also make their appearance
with the first paraphyses.

The formation of the perithecia in Lichens from the primordial coils of hyphae
follows in general the same course as that which has been given for Xylaria and
Polystigma, &c.; but the first origin of the ascogenous hyphae is unknown. Peculiar
features and deviations from rule may be studied in the authors named above,
especially Krabbe and Fiiisting.

CouRSE OF DEVELOPMENT OF THE ASCOMYCETES.

Section LXV. The life-history of the Ascomycetes has been thoroughly
studied in the same species as the development of the sporocarps; there are many
besides in which it is sufficiently known to allow of our comparing them with the
others and judging of them with certainty.

The simplest case is where under normal conditions the germinating spore
developes directly a mycelium or thallus, which also directly produces sporocarps
in the modes described above, without the appearance of any other organs of

224 DIVISION 11.—COURSE OF DEVELOPMENT OF FUNGI.

propagation not belonging to the sporocarp. This is the case in Eremascus albus,
Hypocopra fimicola, Ascobolus furfuraceus, Pyronema, Gymnoascus, species of
Collema, Endocarpum pusillum, Thelidium minutulum, and very many, if not
all, Lichen-fungi; a similar course of development is the almost invariable rule in
Sclerotinia Sclerotiorum, where a filamentous mycelium grows from the germ-tube of
the spore, the mycelium producing sclerotia and the sclerotia sporocarps. Single
resting-cells, which occur accidentally in the mycelia and then resume active growth,
are no more to be taken into consideration in this connection than the soredia
of Lichens which will be described in section CXVII. More distinct formations
of gonidia have not been observed in this course of development.

There is a second case in which the development may proceed as in the first ;
but it commonly happens that a formation of distinct gonidia is introduced, and the
products of their germination resemble those of the ascospores. A good example of
this kind is to be found in Sclerotinia Fuckeliana’. A primary mycelium grows from
the germinating ascospore, and may in the’simplest case produce sporocarps directly
and without going through any intermediate state. I have observed this once and in
one specimen only cultivated artificially in grape-juice on a microscopic slide. The
sporocarp was produced directly from a tuft of mycelial branches, resembling
in appearance the primordium of a sclerotium, but its initial states were not
further examined. The general rule is that sclerotia are formed (p. 34) on the
primary mycelium; then either sporocarps alone: proceed from the sclerotium,
as in Peziza Sclerotiorum, or filamentous gonidiophores, which are known under the
name of Botrytis cinerea, Pers. One only of the two forms appears on a sclerotium,
never both together or one after the other. These gonidiophores may also grow
directly from the mycelium which has proceeded from ascospores, without prejudice
to future formation of sclerotia, but this certainly does not very often occur. Finally,
the germinating gonidia produce a mycelium with all the characteristics of one that
has proceeded from the ascospore and giving rise to the same products, but with this
difference that it inclines much more to the formation of gonidiophores. To
these phenomena is to be added the occasional formation of special abortive gonidia
or doubtful spermatia, which must however be noticed again in section LXXIV.

A third case is that of a number of species in which it must be allowed that the
course of development proper to the first category is posszble, but is never actually
observed. More usually the primary mycelium or thallus formed from the ascospore
always produces gonidia. Strictly speaking, two subdivisions may here be dis-
tinguished :—

a. The primary mycelium which proceeds directly from the ascospore is
reduced to a promycelium (section XXXI) which produces sporidia; these give
rise to the definitive thallus, which then behaves as in the first category or as in
the cases placed under 4. Of this kind is Polystigma rubrum and Rhytisma
Andromedae also, to judge from the germination of the ascospores.

In this case also the formation of gonidia is as a rule a necessary part of the
development, for a perfect fertile thallus is not produced without its interposition.

1 See Pirotta in N. Giorn. Bot. Ital. XIII, p. 130.

CHAPTER V.—COMPARATIVE REVIEW.—ASCOMYCETES. 225

4. A richly vegetating primary mycelium or thallus proceeds from the ascospore,
and its complete development closes with the formation of sporocarps, but as a matter of
fact it always first produces gonidiophores with gonidia. The germinating gonidia again
give rise in all cases to a mycelium or thallus of the same qualities and capabilities as
those which sprang from the ascospore. Here therefore the formation of gonidia
is not necessary to the development, but it is, as a matter of fact, an invariable
occurrence. It precedes the formation of sporocarps in the history of the individual,
and the gonidiophores were therefore often termed the precursors of the sporocarps.

The formation of gonidia is usually extremely copious in this third category,
often much more copious than that of the sporocarps, and then generally owing to
external causes which can be demonstrated; it may be the only mode in which
the species is propagated during many successive generations, while sporocarps
appear exceptionally and under special conditions. Some species have more than
one kind of gonidia, which may then be distinguished according to size as micro-
gonidia, megalogonidia, macrogonidia, or by special names in particular cases according
to other characters.

Again, the gonidia are formed in certain cases on the free surface of the thallus
on single hyphae or in crowded hymenia; or else in receptacles resembling perithecia.
These latter have been termed by Tulasne pycnzdza, and the spores or gonidia formed
in them stylospores—not very happy expressions; the first, however, may be retained
here, the latter replaced by the words pycnospores or pycnogonidia.

All known gonidia in the Ascomycetes are acrogenously abjointed after one
or other of the forms described in section XVI, and none are swarm-cells.

Examples of species which have been fully examined. The germinating
ascospore in the Erysipheae (Fig. 107) puts out a short germ-tube, which on a
suitable substratum, namely the living epidermis of certain Phanerogams, sends first
of all a haustorium (Fig. 6) into a cell of the epidermis, and then developes into the
filamentous branched thallus which spreads over the whole surface. Short erect
branches of this thallus then serially and successively abjoint large colourless
cylindrico-ellipsoid gonidia, and each of these gonidia yields in germination under
favourable conditions the same product as the ascospore. Every thallus which
proceeds from these germinations ends, when it has reached its full development,
with the production of archicarps and antheridia, that is, of sporocarps. But it need not
always arrive at this conclusion, but may only form gonidia and propagate itself by means
of them through an unlimited number of generations. This imperfect development
may usually be traced to obvious external causes, such as climatic conditions or the
absence of the nutrient substance required for perfect development, that is, the proper
species of Phanerogam. The Erysiphe of the grape-vine is the best example of the
group’. From the circumstances attending its first appearance and its diffusion in
Europe, it may be safely assumed that it suddenly migrated, and was transferred to
our vines from some other species of Phanerogam. It most probably came from
America. In spite of its destructive diffusion over the whole of wine-growing Europe
the most careful examination has never detected any sign of a sporocarp; the
invasion was entirely carried out by vast numbers of gonidia, the shape of which
procured the plant the name of Oidium (O. Tuckeri, Brk.). The sporocarps are
probably found in N. America on native species of Vitis and described as Erysiphe
(Uncinula) spiralis, Brk. and Curt., but this is not certain.

! Beitr. z. Morph. u. Phys. d. Pilze, III, p. 50.

[4] Q

226 DIVISION II.-—COURSE OF DEVELOPMENT OF FUNGI.

.The. course of development in Eurotium and Penicillium may be. described in
the same words as in Erysiphe, making allowance for differences of form and for the
circumstance that the species in the two last genera are not epiphytic parasites, but
(for the most part) inhabit dead organic bodies ; here too we find frequent absence
of sporocarps where the vegetative conditions are not altogether favourable. The
gonidiophores of Eurotium (Figs. 94 and 35 4) are erect usually unicellular hyphal
‘branches inflated and bladder-like at the apex, where closely crowded radiating
sterigmata of uniform height are developed, and from these sterigmata spores are serially
and successively abjointed. The gonidiophores in. Penicillium (Fig. 36) are narrowly
filiform, septate, and cymosely branched, and at their extremities, which are erect
parallel and close to one another and terminate at nearly the same height, spores are

“formed by serial successive abjunction. Thggsporocarps of Penicillium glaucum have
‘at present been found only in dark or imperfectly lighted places where the supply
of oxygen is small, and chiefly on bread (Brefeld) ; I myself found them in abundance
on a heap of grape-skins, both growing naturally and after the spores had been sown
by hand.

Fic. 107. J, J] Podosphaera pannosa. I chain of gonidia on the idi and ınycelium. // ripe

the ascus a is emerging through the wall of the sporocarp % which has been rup byp III—V Podosph Cas:
tagnei. III archicarp c with antheridial branch 5 on the mycelium. /Y older state; c archicarp invested by the
hyphal branches of the wall, 4 antheridial branch. Vstill older state in optical longitudinal section; a ascus with its pedicel-
cell, the product of ¢,# the wall 7, // after Tulasne. Magn. 600 times.

The course of development of Melanospora parasitica again is on the whole very
like that of the above species, except that the gonidiophores—short verticillately
branched hyphae with whorls of secondary branches, from which spores are acro-
genously and serially abjointed—are very rarely produced, the work of propagation
falling chiefly to the ascospores. The peculiar parasitism of this Fungus will be
considered in Chapter VII.

The ellipsoidal ascospores of Polystigma rubrum ripen in spring. They put out
a short tube on a moist substratum, and the extremity of the tube, which also swells
into an irregularly ellipsoidal form, receives the whole of the protoplasm, and is then
abjointed and forms a thick-walled spore-cell (gonidium, sporidium). This cell
readily germinates on a moist substratum, and on the epidermis of a foliage-leaf of
Prunus the germ-tube penetrates at once into the nearest cell and there puts out
branches, which then grow rapidly through the wall of the cell into the parenchyma
of the leaf. Here they grow at the cost of the tissue of the leaf and displace its
elements, but always covered by the epidermis, and in a few weeks’ time they have

CHAPTER V.—COMPARATIVE REVIEW.—ASCOMFCETES. 227

formed closely woven thallus-structures (see page 43), which cause roundish red
spots about I cm. in diameter in the still living green leaf; spermogonia and archicarps-
make their appearance in the spots in the course of the summer. The Fungus does
not go beyond the complete development and subsequent fertilisation of the archicarps
during the summer, but falls to the ground in autumn with the leaf, and there the
further development of the perithecium takes place, if the conditions are favourable,
at the expense of the reserve of food in the thallus; the spores become ripe in the
ensuing spring. The process can of course be to some extent hastened or retarded
in plants under artificial cultivation by changes in the temperature and in the supply
of moisture.

The sclerotia of Claviceps purpurea and its nearest allies (see section VIII) mature
during the summer and remain dormant all the winter; in the next spring each

FIG. 108. Clauiceps purpurea, Tul. 4 jum which has given rise to seven FIG. 109. Claviceps purpurea,
stromata. B upper portion of a stroma in median longitudinal section; ¢ perithecia. Tul Ascospores germinating 48
C highly magnified perithecium divided through the middle with the surrounding hours after being scattered on
parts; of orifice, sk cortical tissue, %y inner tissue of the stroma. D ascus isolated; sp water. Magn. 375 times.
ascospores issuing. After Tulasne from Sachs’ Lehrbuch. A natural size. 2 slightly,

C and D highly magnified.

sclerotium, ifit happens to lie on moist ground, usually produces several spherical stalked
stromata (Fig. 108 A), the upper spherical portion of which is thickly covered with
perithecia sunk half-way beneath the surface (B, C). The ejected cylindrical filiform
ascospores (2) swell in different parts under the influence of moisture, and put out
germ-tubes at several points (Fig. 109). If the ascospores of Claviceps have found
their way into young flowers of the Gramineae (Secale in artificial cultivations) under
conditions favourable to germination, their development begins in the pistil, according to
Kühn’s observations, and doubtless after the germ-tubes have penetrated into the pistil,
though this has never been directly observed. The young pistil concealed between
the paleae is first of all traversed in every direction and enveloped by a luxuriant
growth of the hyphae of the Fungus, as has been already described : a white hymenium,
Léveillé’s Sphacelia, then forms on the whole of the furrowed surface, and from cylindrical
sterigmata on it gonidia are abscised (Figs. 110, 111 a). During the formation: of

Q2

228 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

the hymenium the well-known saccharine fluid is secreted, which oozes out from between

the paleae in thick drops
rendered turbid by count-
less gonidia, and thus
betrays the presence of
the parasite. This juice
is eagerly sought by in-
sects, which thus carry
away the gonidia. Soon
the formation of the scle-
rotium begins in the basal
portion of the gonidia-
forming body in the way
already described. The
sclerotium reaches matu-
rity by the time that the
grass is ripe and passes
into the dormant state
which lasts till the next
spring. The gonidia
readily put out germ-
tubes as soon as they
become free, and the tubes
sometimes produce small
upright branches on the
microscope -slide, from
which fresh gonidia are
then abscised (Fig. 111 4).
Kühn informs us that new
gonidiophores and scle-

Fic. 110. Claviceps purpurea, Tul. Portion of athin longitudinal section on the boundary rotia are developed in the

line between the gonidiophore ss—cc and the young sclerotium »z. See Fig.17. After

Tulasne, from Liirssen's Handbuch, highly magnified.

manner described above
from the germ-tubes of

gonidia, which have found their way to the flowers of a grass.
Nectria ditissima may be given from R. Hartig’s description’? as an example of

m

FiG. 111, Claviceps purpurea, Tul. a thin transverse
section through the layer from which gonidia are being
bscised, 4 gonidia inating and producing by abj it

y
a small group of secondary gonidia atx. a after Tulasne,
highly magnified, 4 after Kühn.

a species furnished with more than one kind
of gonidium. The mycelium lives in the rind
of leafy trees, and causes the disease known
as ‘canker.’ It forms a small cushion-like
pseudo-parenchymatous thallus beneath the
surface of the rind; the thallus eventually
bursts through the rind and produces first
gonidia and then perithecia on its . outer
surface. A sufficient account has already
been given of the perithecia, which in the
ptimordial state are concealed beneath the
gonidia and the structures producing them,
but these are displaced and thrust aside by
the perithecia. The gonidia are now formed
acrogenously outside the cushion on short

slender filiform sterigmata arranged side by side and parallel to one another, so as to

% Unters. a. d. forstbot. Instit. München, 1.

See also Tulasne, Carp. III, and R. Göthe, Der

Krebs d. Apfelbäume in Thiel’s Landw. Jahrb. IX (1880).

CHAPTER V.—COMPARATIVE REVIEW.-—-ASCOMFCETES. 229

produce a dense hymenium. The gonidia in the highest state of development are
abjointed successively in long rows forming a close colourless mass which covers the
cushion, each gonidium having the form of a bent cylinder 60 » in length and divided
by transverse walls into several members (spore-cells), which may be as many as eight
in number. Besides these there are some much smaller, but of similar origin, in which
the number of members sinks to two. Each segment-cell of these gonidia may
develope in a moist atmosphere into a branched hypha, from single branches of which
‘fresh smaller gonidia are abjointed. If the mycelium vegetating in the tissue of the rind
of the tree comes to lie exposed in a moist atmosphere, it sends out numerous branches
into the air, and from these also countless small gonidia are abjointed. The size of all
these small gonidia sinks by regular gradations to 1.5 u; they are all cylindrical and
rod-like; those of medium size are divided by a transverse wall into two segments
which often separate from one another; the smallest are undivided. All down to
the size of 2 » can put out germ-tubes or may also multiply by sprouting. The very
smallest have never been observed to put out germ-tubes, but they appear to multiply
by division and fission and by sprouting. Lastly, gonidia of the smallest kind are also
formed in great numbers by slender branches of: the mycelium in the interior of the
tissue attacked by the Fungus. All germ-tubes, whether from gonidia or from asco-
spores, can develope new fertile mycelia in the proper substratum, that is, in the living
rind of a tree; it is doubtful whether the smallest gonidia can produce mycelia
(see section LXXIV). There is also some doubt as to the true nature of certain acro-
genously abjointed spores which occur on the sporocarp-bearing portions of the Fungus
which we are considering; they appear to belong to parasites of Nectria, and it will be
sufficient therefore in this place to refer the reader to Hartig and Tulasne.

The development of Cordyceps with its great variety of forms will be described
subsequently in Division III.

The cycle of development of the one or perhaps two species included under the
name of Pleospora herbarum is particularly rich in forms. These are found in dead
and rotting herbaceous plants. The results which will be given here were obtained
from plants cultivated in nutrient solutions on the microscopic slide. The mycelium
forms (I) the Zerzthecia mentioned above with pluricellular compound ascospores :
(2) gonidia of three kinds produced acrogenously on filiform gonidiophores, namely,—
(a) bicellular or pluricellular spores resembling the ascospores, in general shape shortly
cylindrical to roundish, with dark-brown thick membranes rough with fine points on the
outside, named by Berkeley as a form-species in 1838 Macrosporium Sarcinula and
therefore called by Gibelli and Griffini the Sarcinula-form ; they are usually produced
singly at the end of the gonidiophore ; (6) the Alternaria-form, classed with the old
form-genera Alternaria, Sporidesmium, Mystrosporium, and Polydesmus ; these are coni-
cally pear-shaped pluricellular compound spores having a smooth light-brown membrane,
and arising at the extremities of the hyphae in long and often branched rows (Fig. 34) ;
(c) a form said by Bauke to be a microgonidial form, but of which he gives no further
description; it is not the one known as Cladosporium herbarum and placed by
Tulasne with Pleospora herbarum, for this, according to all later investigations, does
not belong to this place at all and its genetic connection is uncertain: (3) pycnidia
(see below, section LXXI, Figs. 118, 119) which appear as intercalary formations on
branches of the mycelium. A piece of the hypha consisting of one or several cells
swells in the same way as when a perithecium begins to be formed, and its cells
divide at the same time meristematically and irregularly by walls inclined in every
direction. By this process of growth a small-celled parenchymatous body is formed
of many layers, which is round or irregularly elongated in shape and seldom more
than o.2 mm. in size, often much less. This body is at first uniformly dense, but
towards the end of its growth a central cavity is formed in it surrounded by the many-
layered wall ; this cavity is produced by the cells of the central part ceasing to follow
the growth of the outer parts in the direction of the surface and therefore separating

230 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

‘from them. The cell-rows which bound the cavity project into it from the first with
radial convergence, and fresh ones are formed resembling these and between them.
The wall of the cavity is thus lined with slender converging rows of short cells, which
begin at once to form numerous Sycnospores terminally and laterally on all their
cells by successive abjunction. These spores are elongate-cylindrical, very thin-walled,
2.8-4~ in length and about half that breadth, and are surrounded by a hyaline
gelatinous or gum-like substance, perhaps the outer wall-layer. “Imbedded in this
gelatinous envelope they are heaped up in large numbers in the interior of the
pycnidium. When their formation begins the outer wall-layer of the pycnidium, which
has hitherto been colourless, is thickened and becomes brown. At the same time
a narrow opening is formed in the wall usually at one, rarely at more than one, place
by the retreat of the cells from one another, and the orifice is usually surrounded
on the outside by a circle of projecting cells like short papillae. In this state
the pycnidium has reached its full development ; addition of water causes violent
swelling of the mucilage which envelopes the spores, so that they collect into a
gelatinous mass and are squeezed out of the narrow opening in countless numbers,
forming a tendril-like body or a round gelatinous drop according to the degree of
moisture ; they separate at once in water.

All the vegetative cells of this Fungus and its allied forms show a tendency to
form thick brown membranes like those of the perithecia, pycnidia, and gonidia.
With these walls they can pass eventually into a long period of rest and return from
it under favourable conditions to vegetative activity and the formation of spores.
These resting mycelia, and detached single cells or portions of hyphae (gemmae),
may appear in numbers at the close of their culture and add to the variety of
forms.

As regards the genetic relations between all these forms, we are only told of the
microgonidia, that they occur in company with other gonidial forms. Observers also
agree in saying that a mycelium is produced from thee germinating ascospore, and can
first produce gonidia and then perithecia and pycnidia; it behaves therefore in the
same manner as the rest of the gonidia-bearing plants described above as regards
the successive formation of organs of propagation, except in the matter of the pycnidia.
Gibelli and Griffini saw a mycelium proceed also from the Sarcinula-gonidia, which
first produced similar gonidia and then perithecia; sometimes in this case also
the mycelium which has grown from the two kinds of gonidia does not proceed
beyond the formation of gonidia. But the pycnospores, which swell strongly in a
nutrient fluid and even form transverse walls and then put out germ-tubes, produce
a mycelium from them which wp io the present time has never borne anything but
pycnidia in cultures, even when these have been continued through a large number
of generations. It would appear probable that the mycelium could produce
perithecia when growing on its natural substratum, but this has not been proved.
While observers are agreed up to this point, the views of the Italian botanists differ
in other respects from those of Bauke. They are of opinion that two similar but always
distinct species are confounded together under the name of Pleospora herbarum, one
Pleospora Sarcinulae, which is constantly characterised by the presence of the Sarcinula-
gonidia and by larger ascospores, the other Pleospora Alternariae, which as constantly has ~
the Alternaria-form of gonidia. They found pycnidia-only in P. Sarcinulae. On the
other hand according to Bauke a mycelium proceeds from the ascospores of the same
perithecium, which forms ezther pycnidia in company with Alternaria-gonidia or
perithecia with the gonidia of P. Sarcinula. The mycelium from each of the gonidial
forms always produces gonidia of the same kind as the one from which it proceeded.
Further observation must determine which of the two views is correct, but the
analogy of other Fungi makes that of the Italian writers the more probable. The
decision of this question is not important for our present purpose, because, as was

.. intimated above, in the one case we are dealing with one species with a great variety

CHAPTER V.—COMPARATIVE REVIEW.—-ASCOMFCETES. 231

of forms, in the other with two species with fewer forms and in other respects like
one another.

Section LXVI. The remarks which have now been made render it un-
necessary to say anything more concerning the homology of members of the same
name in the Ascomycetes which we are here considering; nor need we further
discuss the fact, that the mature sporocarp contains in some cases only the products
of the development of one archicarp, in others, as in Physma and Pyronema, the
results of the development of several archicarps. We could if necessary establish
sub-forms on this distinction. The question of the homology of the spermatia and
spermogonia is not so readily settled; but even. here the difficulties are not great.
It may be conceded that the consideration of the function of the spermatia of the
Collemaceae puts us on the right track. That function, as will be shown in the
following section, is the same as that of the antheridia in other and allied species.
Hence arises the consideration whether the spermatium with the spermatio-
phore, the sterigma, is not the homologue of an antheridial branch from which
portions are abjointed in the form of spermatia, according to the arrangements of
particular species, in order to be capable of the fertilising function, Forms like
Collema, in which spermatia and archicarps are formed at a distance from one
another, may not afford any sure ground for an answer to the question; but the case
is different with Physma, where spermatia and archicarps spring close together from
branches of the same hyphal coil, like the antheridia and archicarps of Pyronema.
If the spermatia in Physma remained fixed to their spermatiophores in order to
conjugate with the archicarp, the only difference between the two forms would be
that of conformation. The actual differences, it is true, go farther than this, since the
spermatiophores are combined into a spermogonium from which the spermatia are
discharged, and the archicarps are outside of it, and send up the trichogyne to
the place where it encounters the spermatia. But we can understand all these
phenomena as adaptations to suit the origin of the two organs inside a dense
thallus which impedes their direct meeting, and still maintain the homology with
Pyronema. Even the excessive numbers of the spermatia or antheridial branches
will be quite intelligible in view of the very general rule that the number of male
sexual cells in a species increases with the difficulties in the attainment of its
physiological aim. But homology of the spermogonia and archicarps of Physma
with those of Collema is quite obvious ; the latter agree perfectly with the former in
every respect except in their diclinous and monoecious distribution, which in some
forms! inclines to dioecism. But this arrangement is no difficulty in the question
before us, since diclinism may appear everywhere and is actually observed in
many species, in which sexual cells are endowed with free motion whether active
or passive.

It follows from these comparisons and considerations that in Collema also the
spermatia with their spermatiophores may properly be considered to be homologues
of the antheridial branches and antheridia of more simple forms, and the pecu-
liarities of their development, and the excessive numbers in which they are produced

! Stahl, Beitr. z. Entw. d. Flechten, pp. 30, 38.

232 DIVISION II.—-COURSE OF DEVELOPMENT OF FUNGI.

in special receptacles, as adaptations to special circumstances of development, the
further consequence of which is the establishment of diclinism.

It must be admitted that comparisons of this kind are always somewhat insecure
and readily afford too much room for the play of fancy, if they are not supported by
a more complete series of well-known intermediate forms than can at present be
produced in this case. The comparison in the text may be offered with this
reservation attached to it. It appears to me to fit in quite naturally with ascertained
facts; nor is it too much to expect that the intermediate forms that are wanted will
be found, if we consider how few of the whole number of Ascomycetes have been
examined up to the present time.

If we compare the whole course of development of the Ascomycetes in which
this course is fully known with that of the groups of Fungi described in previous
sections, we become distinctly aware of a parallelism between Eremascus and the
Ascomycetes, which are provided with archicarps and antheridial branch on the
one side, and the Mucorini, Peronosporeae, and Saprolegnieae on the other. A
thallus proceeds from the carpospores (ascospores, oospores), and terminates its
development with the formation of an archicarp and antheridial branch and of
the new carpospore which is formed from them. To this the whole course of the
development is limited in many cases, as in Eremascus, Pyronema, and species
of Ascobolus on the one side, and on the other in Pythium vexans and Artotrogus;
in most cases it is interrupted by the formation of other spores, the gonidia. The
gonidia of a species are sometimes all of one kind, as in Erysiphe and Peronospora,
sometimes of more than one kind in the same species. The parallelism extends
even to close resemblance in form in organs of the same name in certain groups.
Eremascus might, to judge from Eidam’s description, be almost ranked with the
Mucorini, especially the Piptocephalideae ; on the other hand, none of the essential
developmental characters of an Ascomycete are wanting in it. In the form of its
archicarps it is perfectly like Penicillium, Gymnoascus, Eurotium and other genera.
There is also a great amount of agreement in respect of the thallus, formation of
the gonidia, archicarp, and antheridial branch between the Erysipheae, especially
Podosphaera, on the one hand, and some Peronosporeae on the other. These
groups therefore establish a nearer connection between the Ascomycetes in question
and the Peronosporeae; a convergence of the two groups which amounts to
actual contact and may be regarded as phylogenetic affinity. This connection with
the Peronosporeae is closest in Podosphaera, because there caeferis paribus not
only the archicarp and antheridial branch are like the same parts in the Pero-
nosporeae, as, for example, in Phytophthora omnivora, but the ultimate develop-
ment also of the archicarp only goes a little further; the eight-spored ascus with
its stalk proceeds from division of the cell twice repeated, while in Phytophthora the
archicarp becomes the oogonium with the oospore. Erysiphe is closely con-
nected with Podosphaera, in which the archicarp by repeated cell-division and
branching gives rise to a number of asci, and all the rest of the Ascomycetes in
question with Erysiphe, as appears plainly from the details which have been given

! For a more extended comparison see Beitr. IV, p. 109.

CHAPTER V.—COMPARATIVE REVIEW.—ASCOMYCETES, 233

above. These comparisons show that archicarps, antheridial branches, and all other
parts of the same name in all the Fungi which are here compared, are homologous.

The homologies go as far as the archicarp; they cease with its further de-
velopment, unless we may perhaps compare the oospore of Cystopus which forms
swarm-spores directly in germination (page 135) with an ascus; the ascus of
Podosphaera and Eremascus is an organ which does not appear in the Peronosporeae,
and this may be said still more of the sporocarp of Erysiphe and the series of forms
which follow it. The series of the Ascomycetes and that of the Mucorini and
Peronosporeae set out on divergent routes from Podosphaera and Eremascus, as the
members which touch one another in the two series. It must not be forgotten
that in this comparison of sporocarps, the parts spoken of above as the ascus-
apparatus are alone to be taken into consideration, and have been considered here.
The envelope-apparatus, important as it isin other connections, does not enter into the
question. For the case is exactly the same if there is no envelope-apparatus, as
really happens in Eremascus, and would be the same if there were Peronosporeae
with their oogonia in envelopes ; this, it is true, has not been observed, but it is quite
possible, and in Mucorini (see section XLII) the zygospores are provided with
envelope-apparatus of great variety of form.

When once the homology between the archicarps of the two groups is proved,
that of all the spores, which have been termed gonidia in the preceding pages, is
also established. The expression was anticipated above throughout in the case of
the Ascomycetes, so far as it was supposed to have exactly the same meaning as
in the Peronosporeae and their nearest allies.

In the Peronosporeae the antheridial branch and the archicarp function
as sexual organs. But homologous meméers need not also function in all cases
as exactly similar organs, as appears at once from the case of the Saprolegnieae with
doubtful sexuality and with sexuality undoubtedly wanting. Hence when the homology
has been established it is still an open question, whether the members of the
Ascomycetes in question are sexual organs or not. To understand clearly this
much discussed question’ we must first of all remember that, in our imperfect
knowledge of the nature of sexuality and the sexual process of fertilisation, we
have no simple mark or reagent by which we can recognise the sexual quality
of an organ. We learn from the facts before us that in every process of fertilisation
there is a material union of one peculiar male or fertilising cell or at least of
a portion of its protoplasmic and nuclear substance with one other, a female
cell, which is to be fertilised, or, as in the Florideae, with a pluricellular female
apparatus?. The result of this union is that the female portion is rendered capable
of further development: the development does not take place without this union, and
union with the male portion is necessary that the female may become capable of
it. In a doubtful case therefore the determination will depend first on the observation
of the union of the protoplasm or nucleus, and secondly on the experimental
proof of the necessity of this in order that the presumed female portion may become

1 See Beitr. IV, pp. 74, 111. We cannot enter here into a discussion of the general question of
sexuality; the beginner is referred to Sachs’ Text-book, znd Engl. ed.
2 See the work cited on page 213, and Fr. Schmitz in the Monatsbericht d. Berliner Acad. 1883.

234 DIVISION II.— COURSE OF DEVELOPMENT OF FUNGI.

capable of development. We may derive assistance also from analogies of cases
which have been certainly ascertained; but these have only a subordinate value,
for experience has certainly shown that sexuality is a phenomenon of irregular
occurrence in the greater part of the vegetable kingdom, varying sometimes from
species to species even in the higher plants, and hence homologies and analogous
functions are here also not necessarily coextensive.

According to these criteria the sexual organs of Pythium, for example, are
really sexual, for the union of protoplasms is evident, and its necessity, though not
demonstrable in strictly experimental manner by artificial separation and conjunction
of the two parts, is all but absolutely proved by the fact that the union always takes
place: but if we apply the same criteria to the homologous organs of the Sapro-
legnieae the sexuality will at least be very doubtful.

_ Similar results are obtained by the same method of determination in the case
of.-the Ascomycetes in question. The protoplasms unite in Pyronema, and
there is no exception to this rule; and as strict experiment is impossible, we
may conclude, as in Pythium, with almost perfect certainty from the constancy
of the phenomenon, that the union is necessary. The phenomena in Pyronerna
-are so far different from those in Pythium that the archicarp grows to meet the
male organ by means of a special organ, the /chogyne, and unites its protoplasm
with that of the male organ; this union takes place after the trichogyne
has previously been permanently delimited as a special cell by a transverse wall.
These facts could hardly be understood but for the exact analogue presented by
the majority of the Florideae. But these make it plain that the trichogyne is
an organ of conception which first receives the fertilising matter, and that the
effects of fertilisation are conveyed from it, in a manner which cannot be further
considered here, to other parts of the female apparatus, which in the present case
is the ascogonium.

We are made acquainted with quite similar phenomena to those in Pyronema,
though different certainly in form and more complex, from Stahl’s observations
on the Collemaceae which have been described above. The most important
complication arises from the fact that the male organs are spermatia detached
by abscision, not antheridial cells formed beside the archicarp. The union
with the trichogyne and the changes which proceed from the place of conjugation
and affect the female apparatus which ultimately forms asci are very apparent.
The necessity of the union for the further development of the female apparatus
is in this case also not shown by strict experimental proof on account of technical
difficulties ; but it is as good as certainly proved by the observation that not only the
union of the spermatia with the trichogyne precedes those characteristic changes
and developments, but that these do not take place if the spermatia for any reason
have not made their appearance.

We are met by the same arguments and results in the case also of Eurotium,
though the facts observed in this case are not so striking at first sight as
in Pyronema; and lastly Eidam’s observations on Eremascus show that the union
of the protoplasms is as evident as it can be in organs which are extremely similar to
those in question in Eurotium, Penicillium, &c. In these cases we may therefore
affirm, that, according to our present criteria, the antheridial branches, or the

CHAPTER V.—COMPARATIVE REVIEW.—ASCOMFYCETES. 235

spermatia which must be supposed to be abjointed portions of such branches, are
in function male sexual organs, and that the archicarps are female sexual organs, and
that the Fungi which produce them possess the power of sexual propagation.

This statement is not admissible in the case of all the other forms furnished
with homologous members. Resting on what we know, we may suspect’ that
in Polystigma the trichogyne and spermatia behave in the same way as in Collema,
but we have no proof of the necessary material union. In Gymnoascus and the Ery-
sipheae, especially Podosphaera, the two organs appear with the same constancy,
one might say with the same morphological necessity, as in Pyronema, and the
possibility of a material union of the protoplasmic bodies is not excluded by the
known facts. The antheridium, it is true, always remains separated from the archi-
carp by a membrane which, as far as we can see, is not perforated, but it
is closely attached to it, and dissolved or very finely comminuted substance may
pass through the membrane, as must be assumed in the case of the fertilisation of
Angiosperms. But after all nothing is proved about the matter; the constant
contact of the antheridial branch proves nothing; the envelope is constantly in the
same position; we cannot get beyond probabilities and possibilities. Beneath the
level of probability we arrive at last at species like Melanospora parasitica and
Ascobolus, which needs revision however in this respect, with a beautifully developed
carpogonium, but with the attachment of the antheridium not constantly or certainly
observed. The conclusion on the whole is, that some of the forms in question have
sexual organs which can be shown to fulfil their functions, others have organs
perfectly homologous with the first, but with the sexual function not certainly
ascertained or certainly wanting.

We have secondly to enquire after the homologies of the Ascomyeetes, in which
there is no distinct archicarp, as far as we at present know, when the sporocarp
begins to appear. We will consider first the extreme cases, Pleospora and Claviceps.
Here the question is, are the parts in these species to be considered as really homo-
logous with those of the same name in the other series which has archicarps, or only
as very similar to them in form and function ; or, expressed in terms of the phylogeny,
do these Ascomycetes belong to a single series of forms descended from the same
stock, or to a/ least two series descended from different stocks only with analogous
ultimate construction? We can only advance probable arguments in deciding between
these alternatives, but these are against the second of the two and in favour of the
unity of the Ascomycetes. First of all the difference alleged is the only one, while
they agree together in all other points of importance to a degree which is else-
where found only in allied forms, and not in those which are merely analogously
developed. Secondly, no other close affinity can be found for the Ascomycetes which
have no archicarps than that with the others; and they must have some relation of
the kind, some connection with other forms. Thirdly, the extremes are evidently
connected together by intermediate forms. The first of such forms is to be found in
Melanospora parasitica with its beautifully developed carpogonium but inconspicuous or
absent antheridium ; other like phenomena appear to occur occasionally! in the series
of the Sordarieae, and these therefore claim the attention of observers. Sclerotinia also

1 See also Zopf in Sitzgsber. d. Brandenb. bot. Ver. 1877.

236 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

is one of this kind. On the other hand, forms like Xylaria, which have Woronin’s
hypha as a transitory formation only, offer transitions connecting them with Polystigma.
Amongst the former cases which connect with Melanospora are forms in which at one
end of the series distinct archicarps are present functioning as certainly asexual (par-
thenogenetic) ascogonia, and along with them distinct elements ofan envelope; towards
the other end of the series the difference between ascogonium and envelope-formation
diminishes till it disappears, and it is only in a more advanced stage of development
ofthe sporocarp that the formation of ascus and of envelope is undertaken by separate
elements, which up to that time were apparently uniform with the rest (Pleospora,
Claviceps). Sexuality therefore is not developed, and in the extreme cases there is
entire disappearance of primordia of the sporocarp which are homologous with sexual
organs. In the other series of cases Woronin’s hypha in the Xylarieae can be under-
stood if we compare it with the archicarp of Polystigma or Collema. It occupies the
same morphological position, but takes no active part, as far as can be seen, in the
formation of the sporocarp, and then disappears apparently without having had
any function to perform, while the formation of the asci is undertaken by neighbouring
hyphae belonging to the envelope. Here then there is an archicarp or ascogonium
present in form, but it remains functionless in the sense expressed by these names,
and the formation of asci falls to the lot of other organs not strictly homologous
with it.

These facts all lead to the result, that in these extreme cases we are in presence
of phenomena, which were spoken of above on page 123 as interruption and restoration
of the homology. Such a conception would perhaps be rash, if we had not before us
the clear cases above mentioned of the occurrence of this phenomenon in Ferns and
Angiosperms ; -but, from our acquaintance with it there, we are led naturally to this
assumption by arguments which have now been stated. The species with an aborted
Woronin’s hypha and a formation of asci at the same time are parallel to the
apogamous Ferns with functionless archegonia and to Angiosperms with an aborted
egg-apparatus replaced by adventitious embryos; the rest approach nearer to simply
parthenogenetic apogamy, as seen in Chara crinita and the Saprolegnieae, but
with the peculiarity that the wap6évos itself entirely disappears in the extreme cases.

In the above discussions the simple forms which have distinct archicarps, such
as Eremascus, Erysiphe, and Eurotium, have been treated throughout as forming an
indivisible group of closely related species, and it has been sought to bring the rest
into connection with them. More is not at present possible. It ought not by any
means to be affirmed that all these forms which serve as points of departure are
connected with the same species outside the Ascomycetes, and that subordinate
parallel or diverging series do not proceed from individual forms among them inside
the circle of the Ascomycetes. It was shown above that Eremascus comes near
the Mucorini, and perhaps special groups of other Ascomycetes connect with
Eremascus. Podosphaera is nearer on one side to the Peronosporeae, on the
other to the main body of the Pyrenomycetes, and so on. But at present we are
not in possession of the empirical material necessary for the enquiry into these details, and
the main results, as here represented, are not decidedly affected by it. The resemblance
also in the development of the sporocarps which we have been considering to that of
the Florideae has necessarily always attracted attention, but whether it points to
an actual closer affinity must for the present remain undecided; other connection
than that to which attention has been called above cannot in my opinion be established.

CHAPTER V.—COMPARATIVE REVIEW.—-ASCOMFYCETES. 237

A nearer approximation of the Ascomycetes generally, or of some of them, to the
Florideae would not materially affect the conclusions at which we have arrived above
with regard to the main questions connected with the homologies.

In my first investigations (Beitr. III) into the development of the sporocarps in
Erysiphe, Eurotium, Pyronema, and others I called the archicarps and antheridial
branches generally sexual organs; and from the great amount of agreement between
the sporocarps when fully formed I expressed the conjecture that all the Ascomycetes
have homologous and analogous organs for the production of these sporocarps.
Others followed me in this view, especially when they became acquainted with
individual cases which confirmed it. The investigations which are here communicated
have had the result of showing that my generalisation was incorrect, and that the mistake
arose not merely from want of consideration of facts not then known, but more especially
from not distinguishing sufficiently between morphological and phylogenetic homology
and physiological analogy. I trust that I have taken this distinction sufficiently
into account in my last special treatise (Beitr. IV) and in this work.

Van Tieghem has been one of the chief opponents of my view, for he takes his
ground on forms that have no distinct archicarps and does not allow of ‘sexuality’
in the Ascomycetes. His opinion briefly stated is this, that the differentiation of
the ascogenous hyphae and their envelopes takes place at stages in the development
of the sporocarp which vary according to the species, and that it occurs at the earliest
possible stage in the species which are supposed to have sexual organs. The supposed
female organ is only an ascogenous hypha differentiated at a very early period, the
supposed male organs are simply part of the envelope-structures. The facts on which
Van Tieghem originally founded his opposition were certainly not happily chosen.
But if he is content to rest his case on Pleospora for instance, or even on the actual
condition of things in Sclerotinia with which he has never been acquainted, he must
be allowed to be quite in the right as against my original conjectural generalisation
literally taken ; and if he objects that the actual sexual function of these organs has
not been proved in the case of Eurotium and Podosphaera, he will find that this
is allowed in my work of 1870. But Van Tieghem makes no enquiry into the
homologies and extends his negation beyond the limits allowed by the facts. If
he had duly considered the indisputable fact of the constant presence in Podosphaera
of my antheridial branch, that is of an organ distinctly different from the later-
formed structures of the envelope and accompanying the proper commencement of
the sporocarp, he would have been led to those true subjects of enquiry which
have been discussed in the foregoing pages, and which it has been attempted to elu-
cidate; and the facts at present known about Pyronema, Eremascus and other forms
should have led him to a different answer to his own enquiries. We need not go
into his positive views with regard to the function of the organs in question, that,
for instance, the antheridial branches serve to support the ascogonium and that the
trichogyne in Collema is an organ of respiration, before it has been shown to be to
some extent probable that the ascogonia are in danger of falling without this support,
and that the particular organ in Collema is obliged to have an apparatus of its own
to get air, and cannot respire without it quite as well as the elements of the interior
of the thallus near which it is placed. Such fancies must certainly deserve the
name of gratuitous hypotheses quite as much as the views which I have here
explained.

Another opponent of my ideas is Brefeld. He wavers between Van Tieghem’s views
on the one hand’, and certain others, which, when stripped of some accessories which
do not strictly belong to the question, agree with those of the present work?, I have
therefore no reply to make, apart from the corrections of some matters of fact

1 Bot. Ztg. 1876, p. 56, Abs. 23, and Schimmelpilze, IV, p. 142.
2 Bot. Ztg. 1877, p. 371, and Schimmelpilze, IV.

238 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI,

which have been made in previous sections. I shall retum in a later page to the matters
which, as I have said, do not belong to this place.

DETERMINATION OF IMPERFECTLY KNOWN ASCOMYCETES.

Section LXVII. The facts detailed in the foregoing pages were established at
first from a comparatively small number of species, but they nevertheless enable us to
pass judgment with tolerable certainty on all the varied phenomena which have been
observed in the countless forms of the Ascomycetes, especially the Pyrenomycetes
and the Discomycetes ; they are a frame in which the latter may be set. It must at
the same time be remembered that very many of these phenomena were known,
named, and provisionally disposed of according to the best knowledge of the time
before a secure basis was laid for a decision respecting them, and that it
was by starting from single phenomena that this basis was gradually reached.
Especially should it be remembered (see section XXXII) that at first every distinct
orm was supposed to represent a distinct species; the gonidiophores of Sclerotinia
Fuckeliana were made a species under the name of Botrytis cinerea, the sclerotia
another species ag Sclerotium echinatum, while the sporocarps by themselves were
made a species of Peziza; in Erysiphe the gonidiophores were supposed to be a
species of the genus Oidium, and only the perithecia were assigned to Erysiphe.
The researches of Tulasne first led gradually to an understanding of the real
condition of things to which he gave the name of pleomorphism, and to him we are
chiefly indebted for the distinguishing and naming of the possible forms in the
development of a species. These researches rested on the broad foundation of the
comparative observation of numerous forms, of their cohabitation, of their anatomical
connection, and their succession in time. Pursued in this way they arrived on the
whole at the truth, and it is a small diminution of their merits that they should have
given rise to some erroneous views on special points, or that they occasionally made
a too extensive application of schemes drawn from a number of observations. This
latter proceeding led indeed to more important mistakes in the hands of some
less careful followers. The task of critical examination could only be satis-
factorily performed after more profound investigation, aided especially by complete
experiments in artificial cultivation; and this has resulted in showing that, owing to the
great number of the species, the differences in the course of development between
the homologous and analogous terminal points which are often very important, and
the frequent symbiotic relation social or otherwise between several species, the
complications may be much greater than would appear at first sight and than can be
expressed by one scheme. Various controversies also have arisen, as appears from
the case of Pleospora described above, out of all these labours and efforts which are
still far from their final conclusion. Much that belongs to this subject is only of
interest in connection with the individual cases and must be referred to in the descriptive
literature. We can here call attention only to the chief points of view, but it will be
well first of all to enumerate briefly the chief phenomena and members of the
development observed in the species above described.

1. From the ascospore is developed a thallus which only produces asco-
genous sporocarps, or archicarps. which produce. these sporocarps together with

CHAPTER V.—COMPARATIVE REVIEW.—ASCOMFCETES. 239 ;

antheridial branches and sometimes spermogonia with spermatia, as in Pyronema,
species of Ascobolus, and Collema. This may be called the simple course of
development in the Ascomycetes.

2. The dimorphous or pleomorphous course of development. Similar
to the simple one in the terminal points being represented by the ascospores, but
Sormations of gonidia are intercalated between them. These formations make their
appearance sometimes as a /ransitory intermediate generation (Polystigma), sometimes
as precursors of the ascocarp on the same thallus, and capable under favourable
conditions of uniform reproduction through an unlimited number of generations.
Excellent examples are Erysiphe, Eurotium, Penicillium, Sclerotinia Fuckeliana.
The gonidia are usually acrogenous, seldom intercalary also, in their abjunction,
‚and are produced—

(a) On solitary simple sporophores, or sprouting cells.

(4) On the exposed upper surface of compound sporophores, as in Claviceps. .

(c) In peculiar receptacles, pycnidia (pycnogonidia, pycnospores, ‘stylospores ’).

Each species can only produce one of these gonidial forms, as is the case with
Erysiphe, or under favourable conditions more than one, as Pleospora and Nectria.

In all cases that have not been thoroughly examined and are therefore more or
less doubtful, an organ or member of the development must be determined and
named according to the agreement of its observed characters with those of thoroughly
known forms. The correctness of the naming will be more or less certain according
to the degree of agreement, and will vary from the extreme of probability to entire
uncertainty. The result of this examination of the separate parts and organs is as
follows :—

Section LXVIII. 1. There is nothing to add here to what has been already said
of the archicarps and antheridial branches.

2. The sporocarps (apothecia and perithecia) with the asci agree so entirely in
the essential points of structure, development, and moment of appearance in the
general course of the development, as they are known to us and have been described
above, that, as has already been pointed out, they may or must be regarded as generally
homologous in the sense and with the modifications above indicated. In by far the
largest number of species, as far as our experience goes, they are the most constant
members in each species in their structure and especially in the structure of the asci
and ascospores. Exceptions to this rule, in which the number or size of the spores
is strikingly unequal in different asci, are comparatively rare, and some instances have
been mentioned above on page 79. Similar cases are recorded in Pleospora and
some other forms. Calosphaeria biformis, Tul. and Cryptospora suffusa, Tul. are
said to have two kinds of perithecia, one of which has asci with a large number of
small spores, the other asci with from four to eight much larger spores}. How far this
is really a case of difference within the same species, and not also of the mixing up
of two similar or associated species, should be enquired into, and the investigation is
rendered more necessary by the question which has arisen in the case of Pleospora
noticed on page 230.

1 Tulasne, Carpol. II.

240 DIVISION II,—COURSE OF DEVELOPMENT OF FUNGI.

Section LXIX. 3. Spermatia, spermogonia. Organs in every respect ex-
tremely like those which are thus named in Collema, Physma, &c. (page 211) are found
in almost all the rest of the Lichen-forming Ascomycetes; the genus Solorina may be
mentioned as an exception among those in which this point has been carefully
examined. These organs occur also in many species which do not form Lichens
both among the Discomycetes and especially among the Pyrenomycetes. On the
ground of these points of resemblance the organs in question are entitled to the
names given to the corresponding organs of the Collemeae and Polystigma, and are at
least to be regarded as homologous with them.

All these organs agree first of all in the formation of sdermatia, small ellipsoid,
or more commonly narrowly rod-shaped, bodies, which are often also bent, as in
Rhytisma, Diatrype (Fig. 114), and Polystigma. Their absolute size varies much in
the different species; those that have the form of narrow rods are according to
Tulasne 6 or 7 a in length in species of Diatrype, and as much as 30 » in Polystigma
rubrum, or less than 6 » in some species of Gyrophora (Fig. 100); the ellipsoid
spermatia of Peltigera have a length of 12-22 a. Their structure, as far as it can be
ascertained, is similar to that of very small and delicate spores with homogeneous

FIG. 112. Valsantvea, Tul. Verticalsection through FIG. 113. Tympanis conspersa, Fr. ha
astroma; in the centre a spermogonium ejecting sper- shortly stalked apothecium with two spermo-
matia; on each side a perithecium. After Tulasne, gonia at its base, in median longitudinal
Slightly magnified. section. Spermatia are escaping from the

spermogonium tothe right. After Tulasne.
Slightly magnified.

protoplasm, and they are formed in the same way as acrogenously produced spores,
being abjointed singly or in rows from short and narrow ends of filaments (sterigmata,
basidia); the latter organs vary in the different species and genera, being either
elongated and cylindrical, unsegmented or with indistinct septa, and forming spermatia
at their apex only (sterigmata in the narrower sense of Nylander), or they are many-
membered cell-rows in which the cells are little longer than broad, and form each of
them lateral spermatia close to their upper end (Fig. roo 2, the arthrosterigmata of
Nylander). This latter form has been chiefly, if not exclusively, observed in certain
genera of Lichen-fungi.

These spermatia are always formed side by side in large numbers, and are
imbedded, as in Collema, in a jelly which becomes hard and brittle as it dries, and
dissolves and disappears in a super-abundance of water. If they are placed with the
jelly in a comparatively large quantity of water, they exhibit a gently tremulous
oscillating movement ; but since this movement appears in spermatia which have
been killed by boiling or by being treated with absolute alcohol as well as in those
which are alive and fresh, it must be considered to be a purely physical phenomenon
due to the motion which is caused in the water by the swelling and partial dissolution

CHAPTER V.—COMPARATIVE REVIEW.—ASCOMPCETES. 241

of the jelly, and which must necessarily be communicated to such small and light
bodies.

With these characteristics the spermatia cannot be certainly distinguished from
small spores. The distinction however is, that, like those of Collema or Polystigma,
they are all, as far as has been hitherto observed, zncapable of germination.

Secondly, these organs all agree in having the spermatiophores collected together
into close hymenia in the spermogonia. These spermogonia are usually, as in Collema
and Polystigma, hollow receptacles like perithecia sunk in the tissue of the thallus,
with the cavity smooth and pitcher-shaped, or, as is very often the case, repeatedly
and very irregularly folded into sinuous depressions and projections, so that where the
folds are narrow the receptacle has the appearance in section of being divided into a

FIG. 114. Diatrype quercina, Fr. a a spermogonium on a piece of bark, laid open by removing
the periderm. The conically pointed upper surface which is folded in coils bears the hymenium of
the spermatia. 6 vertical itudinal section igh a sp jum; a tendril-like mass of sper-
matia is issuing from an opening in the overlying periderm. cfragment of a thin section through

‘the surface of the spermogonium with sickle-shaped spermatia and their sterigmata. After Tulasne.
a and é slightly magnified, c magn. 360 times.

number of compartments. The cavity is everywhere lined with the hymenium which pro-
duces the spermatia, and the spermatia when mature are imbedded in jelly and occupy
the centre of the cavity, and when the jelly swells in water they issue crowded together
in drops or long strings from the narrow orifice of the spermogonium (Figs. 112, 113).

Some Pyrenomycetes which live in the rind of trees form layers agreeing in
every respect with the spermatiophores, except that they are not inclosed in receptacles
altogether belonging to the Fungus; on the contrary they are disk-shaped or cushion-
shaped bodies with the spermatiogenous surface folded into deep sinuous depressions, as
in species of Diatrype (Fig. 114), Quaternaria, and Stictosphaeria, Tul., or else smooth
as in Calosphaeria princeps, Tul., and in both cases covered only by the peripheral
layers of the rind. The spermatia escape through a narrow fissure in the rind,

[4] R

242 DIVISION II—-COURSE OF DEVELOPMENT OF FUNGI.

usually formed above a conical projection in the Fungus-body. Since the agreement
is otherwise so complete we may certainly consider these bodies as spermogonia which
have no outer wall of their own, but are covered over instead by the rind of the tree
which they inhabit. But this affords reason for a further concession and allows us
to give the name of open spermogonia to such cushion-shaped or club-shaped bodies
formed on the surface of the substratum as Tulasne has described in Bulgaria sar-
coides and Peziza fusarioides ; for the outer surface of these bodies is covered with
a hymenium, which, together with its products, behaves in the same way as the
hymenium of the closed spermogonia previously mentioned.

The third and last point of agreement to be observed in all the formations of
which we are speaking lies in their relation in place and in the time of their develop-
ment to the production of the ascocarps. In all cases which have been fully
investigated we find the same arrangement as in Collema and Polystigma; the
formation of spermogonia and spermatia always precedes that of the sporocarps or
coincides with the first appearance of their primordia. At the same time the
formation of spermatia may continue beyond the period of the orientation of the
sporocarps, and both kinds of organs may be repeated more than once on a long-
lived thallus; but this makes no essential difference. The two kinds of organs
usually occur close to one another on the same thallus; dioecious distribution, to
which attention has been called above in the case of Collema, has been observed a
few times in some Lichen-fungi (Spilonema, Bornet, Ephebe pubescens).

We do not certainly know the true function of all the bodies which are spoken
of in this section as spermogonia and spermatia. What we are able to conjecture
on the subject may be gathered from previous sections, and will be considered also
below in section LXXIV.

Section LXX. We have insisted in the foregoing remarks on the invariably
small size of the spermatia, and on their simplicity of structure and incapacity of
germination, or, to speak more correctly, the absence of observed capacity of
germination; and these conditions make it difficult to determine a number of other cases,
which may for the present be placed together under the head of doubtful spermatia.
We learn from a series of observations that there are small rod-shaped or spherical
cells in the Ascomycetes, which have all the known positive and negative characters
of spermatia, but are abscised at other places in the thallus than in or on distinct
spermogonia.

Firstly, such cells are said to occur in the sporocarps themselves, between or
near the asci. Gibelli* states that many Verrucarieae, especially those with simple
spores and without paraphyses in the hymenium, have no proper spermogonia,
but that the lower portion of the perithecium is covered with asci, the upper
with spermatia-forming sterigmata; but other observers? do not corroborate this
statement. We learn from Tulasne that slender branched hyphae, from which
countless small rod-shaped ‘spermatia’ are abscised, are found between the asci at
the places where paraphyses otherwise occur in some but not all the apothecia in

' Sugli org. reprod. del gen. Verrucaria (Mem. soc. ital. di sc. nat. 1),
® Stahl, Beitr. z. Entw. d. Flechten, I, p. 40.

CHAPTER V.—COMPARATIVE REVIEW.—ASCOMPCETES. 243

his Peziza benesuada (Fig. 115); similar organs occupy the margin of the platter-
shaped tube-bearing hymenia of Cenangium Frangulae, Tul. Small round cells
incapable of germination, which will be noticed again in a subsequent page, are
said by Brefeld! to be sometimes abscised from the ramifications of the paraphyses in
Peziza Sclerotiorum.

The second place where these doubtful ‘spermatia’ occur is in the pycnidia of
certain species, in which spores as well as spermatia are produced; such species,
according to Tulasne, are Cenangium Fraxini, Tul., Dermatea carpinea, Fr., D.
Coryli, Tul., D. dissepta, Tul., where the spermatia-forming hyphae also occupy
chiefly the margin of the hymenium, also in D. amoena, Tul., Peziza arduen-
nensis and Aglaospora.

Thirdly, small short-lived cells, which do not germinate and may be compared
with spermatia, are abscised in many species from filiform branchlets of the mycelium
and from the germ-tubes, or even directly from the germinating spores.

Brefeld? found a multitude of such formations on the
mycelium of artificially grown plants of Peziza (Sclerotinia)
tuberosa. From short branches, often with tufts of branchlets
as in Penicillium, are abjointed successively and serially at the
extremities of their ramifications small cells, each containing
a small sphere of a highly refringent perhaps fatty substance,
and these are cemented together by a jelly and thus collected
in heaps on the parent-filaments. Tulasne® found just such
formations on the germ-tubes of the same species and on those
of Peziza bolaris and P. Durieuana when the spores were sown
in water. A similar phenomenon occurs sometimes on old
cultures of the mycelium of P. Sclerotiorum, as Brefeld states
and I can myself confirm ; but, as far as my experience goes,
only in isolated cases which cannot be more precisely defined. Fıc. 115. From the hymenium of

. = R Peziza benesuada, Tul. Ascus sur-
I observed it also on the young germ-tubes of this species, rounded by paraphyses which are

but only in a few and these poor and evidently weakly ÄnerTulasne, Highly magnified.
plants. The small cells mentioned above which are abscised :
in the cups of P. Sclerotiorum are similar, according to Brefeld, to those which
we are now describing. The same formations appear also not unfrequently on
old luxuriant mycelia of P. Fuckeliana grown from ascospores in fruit-juice on a
microscopical slide (Fig. 116); and Zopf found quite similar structures, the narrowly
flask-shaped sterigmata, singly or in a tuft according to the luxuriance of the individual,
on the mycelium of species of Chaetomium, especially on starved specimens, and also
in species of Sordaria (S. curvula, S. minuta, S. decipiens), Woronin having seen them
before in S. coprophila.

Small bodies of the kind here described sprout out directly from the cells of the
multicellular compound spores of Tulasne’s* Peziza Cylichnium when sown in water.

* Schimmelpilze, IV, p. 121.

? Schimmelpilze, IV, p. 113.

® Ann. d. sc. nat. ser. 3, XX, p. 174, and Carpol. III, t. XXII.

* Ann. d. sc. nat. ser 3, XX, and Carpologia, III, pp. 200, 202.
R 2

244 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

The small rod-like cells which sprout from the cells of the spores of Nectria inaurata
and N. Lamyi? while still inside the ascus, filling it quite full and giving rise to strange
misunderstandings, may also be mentioned in this place, though it is not very probable
that they are of the same significance. The point of agreement between all these
forms lies in their outward resemblance and in the absence of any certain knowledge
as to their morphological and physiological value.

Section LXXI. 4. Gonidia. The course of development in the few forms
mentioned above on page 238, 1, is shown with certainty by our observations up to
the present time to be that which is there termed simple ; and almost all Lichen-fungi
also are without gonidia unless we count among them the soredia, which will be
described in section CXVII, as there is certainly good reason for doing ; other gonidial
formations are described in a few species only, as ex-
ceptional cases therefore, and in these are not beyond
doubt.

The course of development in the larger part of the
Ascomycetes with which we are acquainted, and especially
in the Pyrenomycetes, is pleomorphous with copious pro-
duction of gonidia of more than one form. All the gonidia
are unicellular or pluricellular compound spores formed
by acrogenous or intercalary abjunction, as in the ex-
amples which have just been described. Anatomical
investigation and observation of different portions of the
5 development show that they usually appear as precursors

of the ascocarps, whether their development comes to an

FIG. 116. Peziza Fuckeliana. Froma
i grown ona mi ic slide in
grape juice examined under water after
being treated with alcohol. athree young
sterigmata forming ‘spermatia’ at the
top of a branch of the mycelium, the
abjunction shown plainly on the middle
one. & group of five sterigmata before
all the spermatia are shed. ¢ view in
profile of a stout dense tuft of sterigmata
springing from more than one mycelial
filament, the apex of which is formed of
a mass (merely outlined) of spermatia
abscised and imbedded in jelly. Magn.
375 times,

end when the formation or at least the completion of these
begins, or they make their first appearance before the
latter but continue to develope simultaneously with them.
Claviceps, which has already been described, is an excellent
example of the first case, for gonidia and perithecia follow
one another in that genus in successive periods of vege-
tation. The development of species of Stigmatea accord-
ing to Tulasne?, and probably of some other small Pyre-
nomycetes that live in leaves, follows a similar course, but

without forming sclerotia ; and this is the case also with Epichloe, which was described
in a former page, and with Tulasne’s Xylarieae (Xylaria, Poronia, Ustulina, Hypoxylon)
and some species of Nectria, especially N. cinnabarina (= Tubercularia vulgaris, P.),
which all behave in a similar manner to Epichloe. The compound sporophores
of these forms are at first covered by a hymenium which produces gonidia, but this
ceases to grow and is cast off as soon as the development of the perithecia formed
within its plane of insertion begins to advance.

A second case is exemplified in the Erysipheae mentioned above, in Fumago
salicina®, Cucurbitaria macrospora (Fig. 117), Pleospora polytrichum, P. Clavariarum *,

1 See Janowitsch in Bot. Ztg. 1865, p. 149.
® Tulasne, Carpol. II.

2 Carpol. II.
4 Tulasne, Carpol. II.

CHAPTER V.—COMPARATIVE REVIEW.—-ASCOMYCETES, 245

and some others. Ripe and “ripening perithecia may in these plants stand side by
side on the same mycelium or stroma with developing gonidiophores.

It is scarcely necessary to remark that the succession of events does not always
proceed in these examples with perfect regularity; and the instance of Peziza
Fuckeliana described above on page 224 shows that considerable deviations from it
may and do occur.

As regards the point of origin of the gonidiophores and their arrangement and
structure, it would seem that they occur in particular species in the ascocarps them-
selves, like the doubtful spermatia noticed on page 242. According to Berkeley’
single paraphyses are found between the asci in Sphaeria oblitescens B. et Br., in which
one or two of the cells are enlarged into somewhat elongated septate ‘spores;’ the
terminal cells of such paraphyses in Dothidea Zollingeri, Berk.’ are like simple
ellipsoid spores. Berkeley* makes a similar statement in the case of a species of
Tympanis and for Lecidea Sabuletorum * or an allied form; but these points require
re-examination, as Tulasne has intimated®, because we are still ignorant of the
qualities of these spore-dike bodies.

Putting aside these few doubtful and possibly exceptional cases, all gonidial
formations conform to the examples described above which have been thoroughly
examined. The following special forms may be enumerated :—

(a) Free filiform gonidiophores; often very characteristic in their conformation,
as in Penicillium, Eurotium, Erysiphe, &c., and in such cases formerly assigned to
established form-genera. Thus species of Hypomyces were assigned to the form-
genera Verticillium, Sepodonium, and Mycogone of the old descriptions, and
Fusisporium Solani®; species of Nectria to Fusisporium and Spicaria of the old
descriptions, and many other cases might be cited. To these may be added some
other forms, in which the distinction between gonidia and gonidiophores on the one
hand and portions of the mycelium on the other is less sharply defined, and may even
be arbitrary in each individual instance up to the extreme cases in which each cell
of a hypha or a hyphal strand first performs the part of a mycelium and then
assumes the characters of a spore. The latter is in extreme cases naturally
termed the formation of resting mycelium and has been elaborately studied by Bauke
and Zopf, especially in saprophytic Pyrenomycetes, though older observers often men-
tioned it incidentally. It occurs in old and specially in starved mycelia for example
of Pleospora, Fumago, and Cucurbitaria, in which the cells of the mycelium
acquire thick and usually brown walls, store up reserve food material, and pass into a
dormant state, and subsequently under suitable conditions germinate as spores.
Changes of form, especially swelling of the individual cells into a spherical shape, may
or may not accompany the changes which characterise the state of rest, and hence the
resting states differ in very various degrees from the vegetative mycelial forms.

X Ann. Mag. Nat. hist. ser. 3, III, p. 373, t. XI, 32.

2 Hooker’s Journ. III (1844), p. 336.
-® Introd. Crypt. Bot. p. 244.

* See Ann. Mag. Nat. Hist. ser. 2, IX, and Crypt. Bot. p. 391.

5 Mem. ». les Lichens, p. 110.

© Reinke u. Berthold, Die Zersetzung d. Kartoffeln durch Pilze, 1879.

246 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

(6) Dense hymenia giving off gonidia by abscision on the free ouler surface of
compound sporophores. Examples of this kind are Claviceps (page 227), Epichloe,
the Nectrieae before mentioned, Xylarieae (Fig. 103 A), Cucurbitaria macrospora
(Fig. 117), and many others. The form of the separate gonidiophores which together
constitute the hymenium, the special mode of abjunction of the gonidia, and the
structure and form of the gonidia themselves, all vary extremely according to the
species. And again it depends on the species whether the formation of gonidia is
entirely, or almost entirely, confined to these hymenia or to the stromata which bear
them, as is the case in Nectria cinnabarina and the other genera last named, or
whether gonidia-forming hyphae of like structure occur either united into hymenia
or appearing singly on a filamentous mycelium as in the Hyphomycetes, as happens
in Nectria Solani and Hypomyces Solani’.

Whether we have always to do with gonidia in the cases which have been given
as examples, especially in the Xylarieae, or sometimes also with non-germinating
spermatia, is often uncertain and must be determined in each separate case.

(c) Pycnidia: receptacles (conceptacles) of more or less similar character to
those described in Pleospora, and producing gonidia which are known as pycnospores
or pycnogonidia or more commonly as
stylospores. They are wanting in many
or most species of Ascomycetes, in all
forms, for instance, mentioned under 6
and in most of those mentioned under a,
and in almost all Lichen-fungi. They
were said indeed to have been found by
Lindsay in Bryopogon jubatus, Kbr.,
Imbricaria saxatilis and I. sinuosa, Kbr.;
by Gibelli in ‘ Verrucaria carpinea, Pers.,’
Sagedia carpinea, Mass., S. Zizyphi,

Mass., S. callopisma, Mass., S. Thuretii,

FIG. 117. Cucurbitaria macrospora, Ces.andde Not. a stroma. 5 m y

in longitudinal section ; ? developed perithecium, c layer of gonidia. Kbr., Pyrenula minuta, Näg., P. olivacea,

amo ee Der Verqoaria Gibelliana, Garov.; by

Fiiisting in Opegrapha varia, Acrocordia

gemmata, Mass., A. tersa, Sagedia netrospora, Hepp., and S. aenea. "Lindsay's account

also of two kinds of spermogonia in Roccella Montagnei, Bel. and Opegrapha

vulgata, Ach. may be mentioned here since some of the receptacles which he termed

spermogonia may be pycnidia. But in all these cases we know so little concerning

the development of the organs in question that it is still uncertain whether they belong
to the species named above or to parasites living in their thallus.

The pycnidia, like the perithecia, are according to the species either formed
singly from the filamentous mycelium, or are placed in or on compound pycnidio-
phores (stromata), as in Cucurbitaria Laburni, Dothidea Melanops, &c.? Their
development proceeds, in several cases that have been observed, in the manner

' Reinke u. Berthold, Die Zersetzung d. Kartoffeln durch Pilze, 1879.
* Tulasne, Carpol. II.

CHAPTER V.—COMPARATIVE REVIEW.—ASCOMYCETES. 247

described above on page 229, in the case of Pleospora; an intercalary portion of a
mycelial filament grows by successive divisions which arise without fixed order in
every direction, and the cells thus formed are subsequently differentiated, while branches
from adjoining hyphae usually grow up round the new body and thus help to form its
wall (see Fig. 118). This is the mode of formation according to Gibelli and Griffini,
Eidam and Bauke not only in Pleospora herbarum, but also in Cucurbitaria elongata,
Leptosphaeria doliolum and two other species not precisely determined, and according

5

FIG. 118. Pleospora Alternariae, Gibelli. (Determination not certain FIG. 119. Cicinnobolus Cesatii (De Bary, Beitr. III), para-
from the absence of perithecia.) Young stage of development of pycnidia. sitic on Erysiphe. Aripe pycnidium (seen from without)
a of the ing and rapid transverse division of the open above on the left and discharging its sporess, having de-
intercalary portion of a hypha, which is developing into a pycnidium and veloped in a gonidiophore of the Exysiphe which is attached
has branches from itself and from an adjacent hypha attached to it. tothe mycelial filament x x and bears four dead gonidia ¢ on
6 older stage of the development. The mature structure of these pycnidia itssummit. 2asmallandnearly ripe pycnidium, formedona
closely resembles that represented in Fig. 119, only the wall is formed of branch of a mycelial hypha 2 m of the Erysiphe, in which
several layers, Magn. 600 times. the slender mycelial hyphae of the Crciznobolus may be
seen. The figure shows the upper surface and the optical

longitudinal section of thet ent peridium ; the section

shows the young spores growing inwards from the one-
layered wall. C tranverse section through the wall of a ripe
pycnidium with three primordial spores sprouting inwards.
D two ripe spores just di: d from the pycnidium and
a germinating spore. 4 magn. 380, 5, C 600, D 300 times,

to Zopfin some pycnidia of Fumago ; Brefeld’s ‘Pycnis sclerotivora’ must also be added
to the number. Other pycnidia are not meristogenetic but symphyogenetic formations,
that is, they are produced by union and interweaving of hyphal branches; such are
those known under the name of Cicinnobolus, some in the genus Fumago, and
the Diplodia-form examined by Bauke. The formation of the pycnidia in Pleospora
polytricha, according to Bauke, is of an intermediate kind, the inner portion being
meristogenetic and the numerous outer wall-layers symphyogenetic. The structure of
pycnidia formed in these different ways may be quite alike in the matured state, as is
seen by comparing Cicinnobolus (Fig. 119) and Pleospora.

248 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

The shape of the pycnidia isin general the same as that of perithecia or spermo-
gonia, and the internal cavity, like that of the spermogonia, is according to the species
either simple or divided by projections from the wall into usually irregular narrow
compartments communicating towards the orifice. The pycnospores of the different
species exhibit the usual variety of modifications in the structure of spores. Two
extreme forms may if necessary be distinguished : small-spored pycnidia (corresponding

. to the old form-genus Phoma) with very small, colourless, somewhat elongated spores,
which are imbedded in mucilage and are discharged in masses from the orifice of the
pycnidium, as in Pleospora and Cucurbitaria elongata, and Jarge-spored pycnidia
with comparatively large either simple or compound spores, the walls of which are
often thick and of a brown colour.

Section LXXII. In the species of which we are now speaking, as well as in those
previously described and which have been thoroughly examined, the different forms of
gonidia and gonidiophores occur according to the species in the greatest
possible variety of combinations with the perithecia and sometimes with
one another. Examples of this, such as may be considered to be well ascertained, are
to be found in the works here quoted, and especially in Tulasne’s Carpologia. Some
of the accounts contained in this book, and still more those in the more recent de-
scriptive writings, must be accepted with caution. We may here call attention more
distinctly to the fact, which may be gathered indeed from some of the previous remarks,
that each species has the faculty of forming asci and gonidia within broader or
narrower limits as the result of its inherent inherited qualities; external causes,
especially the quantity and quality of the food at its disposition, then determine in a
variety of ways the phenomena which are actually observed. A few examples will
now be given in illustration especially of the latter point, which will be further
discussed in section LXXIII.

The genera Ustulina, Poronia, and Hypoxylon among the Xylarieae may be con-
sidered, as far as we at present know, to be plants of one form, since, like Epichloe
(and Claviceps), they produce gonidia of ome definite form on the young stroma,
and then perithecia.

Cucurbitaria Laburni! forms in the dead rind of Cytisus Laburnum large flat
roundish cushion-like stromata which reach a breadth of some millimetres and finally
issue from the ruptured periderm covered with numerous black round spore-receptacles.
Some of these are perithecia, some gonidial receptacles, pycnidia, with a single cavity
and a narrow canal at the orifice ; a stroma according to Tulasne may bear only peri-
thecia or only pycnidia, but usually has both and more than one kind of pycnidium. In
the latter case the receptacles make their appearance on the stroma, which increases
in size while they are forming, in adox? the following order in time and centrifugal
succession :—

1. In the middle of the stroma one or a few comparatively large colourless pycnidia,
producing colourless thin-walled unsegmented cylindrico-elliptical spores 5-10 u in
length, on short sterigmata.

2. Numerous pycnidia with thick black walls in which are abscised from short

sterigmata

(2) Colourless spores of very unequal size,

1 Tulasne, Carpol. II, p. 215, t. XX VII.

CHAPTER V.—COMPARATIVE REVIEW.—-ASCOMTCETES. 249

(6) Spores with dark brown walls, nonseptate or with one transverse wall, closely
resembling the spores of No. 1 in form and size,

(c) Brown spores like the last but pluricellular compound, 20-30 » in length and 7-10 u
in breadth.

Each of these spore-forms generally occurs separately in a special receptacle, so
that four kinds of pycnidia may be distinguished ; but combinations are also found
especially of (a) and (c) in the same receptacle.

3. The perithecia.

The formation of germ-tubes has been observed in all the forms of spores produced
in the pycnidia. No other gonidial forms are found in Cucurbitaria Laburni.

Species of Hypomyces are characteristic examples of the regular formation of two
kinds of gonidia; these plants, like Hyphomycetes, live on the larger Fungi, especially
the Hymenomycetes, Hypomyces rosellus for instance, H. chrysospermus, and other
species’, or on parts of dead plants, as H. Solani on rotten potatos?. Besides the
perithecia which are comparatively rare, and are always later in their appearance,
the mycelium produces

(1) Microgonidia, comparatively thin-walled and colourless, but tolerably large, ellip-
soid, cylindrical, or fusiform unicellular or compoundly pluricellular spores, which are
abjointed successively and form small heads at the extremities of the ramifications of
verticillately or irregularly branched gonidiophores, and were assigned to the old form-
genera Verticillium, Dactylium, Fusisporium, and others.

(2) Megalogonidia or macrogonidia, sometimes also called chlamydospores, acroge-
nously formed and solitary or more rarely appearing a few together one behind another
on branches of the hyphae which produce the microgonidia ; their formation generally
begins later than that of the microgonidia, from which they are distinguished by
their thick membranes, which are often rough with warts and usually coloured, and in
most species by their greater size; they are unicellular or compound pluricellular
according to the species. The thickness of their membranes shows that they are
adapted to a persistent state of rest.

Reinke and Berthold have shown that in Hypomyces Solani mycelia are formed from
the germ-tubes of both kinds of gonidia as well as of the ascospores, which can again
produce both kinds of gonidiophores, and Tulasne’s less complete account agrees with
theirs. More complete knowledge of the general course of development has not yet
been obtained.

Zopf’s Fumago* may be adduced here in conclusion as an example of a cycle of
forms still more copious and varied than that of Pleospora or Nectria ditissima which
have already been described. Though Zopf found no ascocarps in his Fungus, yet
I place it here with the Ascomycetes, because according to Tulasne‘ the very similar
species Fumago salicina has ascocarps, and because we are specially considering
at the present moment the Ascomycetes which are not yet quite perfectly known. The
species of Fumago are the soot-dew which is found in the form of black fuliginous
coatings covering parts of living plants. Zopf studied his plants chiefly in pure
cultures on microscopic slides in nutrient saccharine solutions of various degrees of
concentration, and ascertained the agreement of the cultivated forms with those which
occur in nature.

1. The mycelium of the Fungus is composed of hyphae with short segments, which,

like the cells of the gonidiophores, acquire usually at an early period a brown coloration
of the walls accompanied by a gelatinisation of an outer colourless layer, while the

1 See Tulasne, Carpol. III.

? Reinke u. Berthold, as cited on page 245.

* Die Conidienfriichte von Fumago (N. Act. Leopold. XL).
* Carpol. II.

250 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

cell-contents develope much fatty matter. The gonidia are formed acrogenously on
distinct gonidiophores, or in gonidial receptacles, and may be termed acrogonidia. They
are when first matured small thin-walled colourless ellipsoidal cells with a gelatinous
outer covering and a small drop of fatty matter in the focus; in size they are
4-5 » in length and 2 » in breadth, and are formed in a variety of ways.

(a) In specimens grown in a poor solution (containing at most five per cent. of
nutrient matter) and kept as dry as possible the poorly developed mycelium produces
small slender filiform erect gonidiophores composed of a few cells, which form their
acrogonidia successively like heads at their apex, or in whorls beneath the upper end
of their subterminal cells (Zopf’s formation of microgonidia).

(6) Stronger mycelia are developed with a more generous supply of food, and these
produce erect tufts of many-celled hyphal branches on which acrogonidia are formed.
From 2-12 of these branches grow close together, at first closely parallel to one another,
but afterwards diverging at an acute angle, and may be nearly a millimetre in height ;
the branches in a tuft are of a nearly uniform height. The lower cells of each hypha
are elongated and cylindrical, the upper short, scarcely longer than broad, and from
them proceed other branches with short cells usually placed on one side only of
the cell from which they spring, and rising in the same direction and to nearly the
same height as the primary branch, thus resembling to some extent the tuft of
branchlets at the extremity of the gonidiophore of Penicillium. From the short cells
of all these tufts of branchlets acrogonidia are abscised, terminal ones at their apex,
the rest near their upper bounding wall, and all usually on one side and in the same
direction.

(c) The tufts of gonidiophores formed on the mycelium in the way described under
division (4) may be firmly united into a bundle along their whole length, while their
other characters remain the same. This bundle is at first nearly cylindrical, but its
apex spreads out into the shape of a funnel as the terminal ramifications are being
formed which will produce gonidia, and their extremities spread out from one another
in a penicillate manner; the abscision takes place only inside the funnel-shaped
enlargement, the outer side remains sterile, and the pointed barren extremities of
its hyphae extend with a slight divergence a short distance above the tuft from which the
gonidia are abscised.

(d) The sterile extremities of these hyphae may unite laterally and firmly into a
narrowly conical tube open at the top, and grow out far beyond the region which
supplies the gonidia; in other words they form a symphyogenetic gonidial receptacle,
a more or less elongated flask-shaped pycnidium. The ventral portion of the flask
is the region from which the gonidia are abscised, and Zopf found that the process was
always carried on from the cells of the wall which continues to be of one layer, and not
from other hyphal branches which project into the interior of the tube.

(e) Lastly, pycnidia of essentially the same definitive structure as those in (Z) only of
roundish less elongated form, with a wall that is usually two-layered, may also be
formed meristogenetically. .

Intermediate forms are found, as might have been expected, between the formations
described above from (c) to (e) inclusively.

2. The acrogonidia when sown in a dilute (five per cent.) nutrient solution sprout
and form successive roundish ellipsoid sprout-cells like those of Saccharomyces
Cerevisiae! if the supply of atmospheric air is restricted ; with free admission of air the
sprouts are frequently elongated cylindrical shoots (the ‘ Chalara-’ and Mycoderma-
form).

3. All the parts and forms of the Fungus which have now been described may pass,
if the supply of food diminishes slowly, into resting states under a great variety of
particular forms, while the cells swell, acquire a brown colour and store up fatty

1 But they incite no alcoholic fermentation.

CHAPTER V.—COMPARATIVE REVIEW.—ASCOMYCETES. 251

substances; thus we get resting gonidia, resting gemmae, and resting mycelia, the
latter often appearing as torulose filaments or crust-like masses. All the gonidial and
resting forms are capable of germination under favourable conditions, and al che forms
included in divisions 1, 2, and 3 may be changed into one another if the conditions of
growth are suitably varied.

We must not enter here into the question whether Fumago has other organs of
propagation besides the perithecia which are said to occur and those which may
possibly occur, though it is one which may very well be asked after Tulasne’s account
of F. salicina!.

Section LXXIII. It is almost to be expected in the case of pleomorphous
species of Ascomycetes, that only separate members of their form-cycle should often
be found on a substratum at any given time, whether ascocarps or gonidio-
phores or gonidial receptacles. The frequency of this occurrence in a particular
species will depend on the ease with which it spreads as a rule over different kinds
of substrata under a great variety of external conditions, and on the other hand, also
on the strictness with which it is tied to special conditions of vegetation, in order to
produce the particular member which closes the cycle. Examples are seen in the
species of Fumago, Pleospora, and Penicillium, and in Sclerotinia Fuckeliana which
have been described above; the mycelia of these Fungi bearing simple gonidiophores
are of universal occurrence in the form of Moulds, and they are propagated in the same
form, while the sporocarps are much more rarely found; the conditions under which
they occur in the first two genera are not yet precisely ascertained’; in Penicillium
they are produced on plants artificially grown on bread and spontaneously on the
skins of grapes that have been pressed for wine, and in Sclerotinia Fuckeliana only
on sclerotia which have developed and arrived at a certain degree of maturity on
particular foliage-leaves (Vitis, Castanea, Quercus); a large number even of the
sclerotia of this species produce only new gonidia, as is especially the case with those
which are so common on dead cabbage-stalks, the Sclerotium durum of old writers.
The majority of known species which form gonidia behave in a similar manner;
the converse proceeding, a comparatively copious formation of sporocarps with
scanty production of gonidia, is comparatively rare, though it does sometimes occur,
as in Melanospora parasitica. Many or indeed most of the gonidial forms of species
that are now better known were for these reasons described as form-species, before
their genetic relations had been ascertained, and were distributed into corresponding
groups, the pycnidia and spermogonia being arranged in the Sphaeropsideae,
Cytisporeae, and Phyllosticteae *, the simple hyphal gonidiophores and open hymenial
layers in the Hyphomycetes, Haplomycetes, and Gymnomycetes of Fries. Proof of
this statement is to be found in the special descriptive literature, to which reference
here is unnecessary, since the historical facts are of the same kind as those to
which attention was called above in the case of the Mucorini, Peronosporeae, and
other forms.

Another fact which was noticed in the description of those groups is also
repeated in the Ascomycetes, namely, that there are forms which strongly resemble
the members of the development of thoroughly well-known species, some even

1 Tulasne, Carpol. II. 2 Ibid. ® Fries, Summa Veget. Scand. II.

252 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

exhibiting the same comparatively minute specific distinctions, but in which the
formation of an ascocarp such as belongs to the particular development
has never been observed, while at the same time there is no reason for considering
that they belong to any group outside the Ascomycetes. We are compelled by this
condition of our knowledge to regard these isolated forms as homologous with those
which are like them and the position of which is known in the course of development
of other species, and to call them accordingly spermogonia, gonidiophores, pycnidia,
or the like; it is true that this practice is founded only on probabilities, but it has
already found its justification in many cases in the strict proofs which have been
subsequently obtained. Most of the Haplomycetes, Gymnomycetes, Sphaeropsideae,
&c. of the old systems, one might indeed say all of them that do not belong to the
groups described in the previous sections, fall in this way and in accordance with the
present state of our knowledge into the class of Ascomycetes, some connecting
immediately with well-known ascomycetous species, others through the forms first
mentioned; the grouping of the very large number of species and particular
forms is necessarily attended with practical difficulties of a different kind from those
which are met with in dealing with the few dozen Mucorini or Peronosporeae.

While referring the reader to the descriptive literature of this subject, it may be
well to mention a few names in illustration of the above remarks ; most species for
instance of the old form-genera Naemaspora, Cytispora, Libertella, Septoria, Lepto-
thyrium, Phyllosticta, Cheilaria, Gloeosporium, Spilosphaeria, Ascochyta, Phoma,
Diplodia, Myxocyclus, Hendersonia, Sporocadus, Sphaeropsis, Cicinnobolus, Ehr. and
some others must be classed with the pycnidia and partly also with the spermogonia ;
species of the form-genera Cylindrosporium, Oidium, Dematium, Conoplea, Periconia,
Cladosporium, Helminthosporium, Macrosporium, Dendryphium, Mystrosporium,
Brachycladium, Sepedonium, Mycogone, Aspergillus, Verticillium, Polyactis, Botrytis,
Fusisporium, Alternaria, Torula, Isaria, Stilbum, Atractium, Graphium, Melanconium,
Stilbospora, Steganosporium, Coryneum, Exosporium, Vermicularia, Tubercularia,
Sphacelia, and many others, whose affinity to undoubtedly typical Ascomycetes is either
certain or very probable, go with the, filamentous gonidiophores and open gonidia-
bearing hymenia. To these may be united with the needful reservation a large number of
forms, in which the mycelium and the formation of spores, which must be considered
homologous with the gonidia, are all that is at present known. Some of these forms do
actually belong to the above form-genera, for the determination of these genera was made
to rest on certain particulars of conformation which in some cases appear to our present
knowledge to have been very superficially examined, and which, as we have since
learnt, may occur in very various genetic connections. For instance Oidium leuco-
conium, Desm. and O. erysyphoides, Fr. are names for the gonidiophores of Erysipheae.
Oidium fructigenum, Kze. and O. lactis, Fres. are somewhat similar forms which do
not belong to the Erysipheae and whose genetic affinities are quite unknown ; Botrytis
cinerea is the name of Sclerotinia Fuckeliana when it produces gonidia; B. Bassii
denotes an isolated gonidial form by no means closely related to the last-named
Botrytis. Other forms of this series are so widely different from those named above
that the old describers gave them distinct generic names; thus they called their
Hyphomycetous forms Arthrobotrys, Gonatobotrys, Haplotrichum, Cephalothecium,
Stysanus, &c. &c.

These forms are for the present arranged with the Ascomycetes, because from
what we know of them they appear to have more connection with that division
than with other Fungi; but they are only known to us under one form, which may be
considered to be that in which they produce gonidia.

CHAPTER V,—COMPARATIVE REVIEW.—ASCOMYCETES. 253

It may be affirmed of the majority of the species which have just been con-
sidered, that they are imperfectly known, because no attempt has been made to
ascertain the entire course of their development. But some among them have not
only been observed in the mature state or occasionally grown from the spores, but
have been repeatedly submitted to long and careful observation and cultivation; and
yet they are only known to produce the same supposed gonidial forms, and there
is no sign of ascocarps or of any other member of the development, which
the analogy of very similar forms in well-known species would have led us to expect
from them. The large species, Aspergillus clavatus? for instance, has never been
known to produce anything but gonidiophores; the sporocarps like those of Eurotium
and Penicillium, which were to be expected from the structure of the gonidiophores
and of the mycelium, never made their appearance either in Wilhelm’s many experi-
ments in the artificial cultivation of the plant, which were made for the purpose
of determining this point and were conducted under a variety of conditions, nor in
many others which I have myself often repeated in the course of years. Botrytis
Bassii? is a very common insect-destroying Fungus, which in the character of its
vegetation is very like Cordyceps militaris, but resembles another Pyrenomycete,
Hypocrea rufa*, in the way in which it forms its exposed gonidia; hundreds of
cultivated specimens of the plant have produced only the same organs bearing
gonidia, never a sign of perithecia ; my conjecture *, which has become an assertion
in Brefeld *, with regard to the latter has proved therefore to be incorrect. The same
must be said now of another insect-killing form which agrees very closely with
Cordyceps militaris in the mode also of forming its gonidia, and which I have
described under the name of Isaria strigosa®. Another instance which may be
noticed here is the universally distributed and repeatedly cultivated Oidium lactis;
this plant never produces anything but the mycelium with cylindrical serially abjointed
gonidia’. ‘The common Cladosporium herbarum, Lk. also should not be forgotten
in this connection. Further instances of this kind have been discovered in the course
of the investigations which have been made into the pycnidia. I refer to Zopf’s
account of Fumago of which a resume has just been given. Brefeld® cultivated a
pycnidia-bearing form, a not uncommon parasite on the sclerotia of Sclerotinia,
under very varied conditions through more than a hundred successive generations,
without ever obtaining anything but the pycnidium-form. Similar results are
recorded for other species in Bauke’s work on pycnidia; Ehrenberg’s Cicinnobolus, a
parasite on Erysipheae*, may also be quoted here, and it may be added that the
pycnidial forms mentioned here are so like others which undoubtedly belong to
typical Ascomycetes, that they may be readily mistaken for them.

In view of these facts of experience the question again arises which was
discussed above in connection with the Mucorini and Peronosporeae whether we
have before us species which are only imperfectly known to us, and which under

1 Desmaziéres in Ann. d. sc. nat. ser. 2 (1834), II, tab. II. Fig. 4.—K. Wilhelm, Dissert. p. 62.

2 See Bot. Ztg. 1867. ® Bot. Ztg. 1869, p. 590.
° See Tulasne, Carpol. III. ' See above at p. 67.
* Bot. Ztg. 1869, p. 590. ® Schimmelpilze, IV, 122.

5 Schimmelpilze, IV, p. 136. ® Beitr. III, and above, Fig. 119.

254 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

\

certain conditions do really fill up the gaps in our knowledge, that is, are able to
produce the typical ascocarp of an Ascomycete; or whether there are species
which in their known characters do come near to typical Ascomycetous genera and
may even be included in them, but do not at present actually produce the ascocarp
of an Ascomycete. In the latter case a further question arises, whether and how
far the problematic defect comes from the loss of the capacity or from its having
never been possessed. The attempt to examine and answer these questions leäds us
necessarily into the domain of conjecture, and forces upon us the reservations here
proposed. Every new unexpected fact may change the grounds of the decision.
If we begin with the second question from the stand-point of our present knowledge,
we must conclude that the plant has Jost the capacity, as long as the views on the
unity and affinity of all the Ascomycetes and on their homologies and connection
with the Peronosporeae, which were developed above in section LXVI, are not shown
to be incorrect. This is the necessary result of what has been already stated and does
not require to be again explained. Whether the loss has in every case directly‘
befallen the species 5 under observation, or another z from which 4 is descended,
must remain an open question and is not an essential element in the matter. The
assumption of such a loss would also be in harmony with other known facts in the
Fungi which imply retrogression in the development of a species with excision of
certain members (see below in section LXXXII). Moreover there are distinctly observed
facts within the group in question, which enable us to form a clear idea of the way
in which this loss may be occasioned ; but these very facts themselves compel us to
be cautious and to leave it to time to give a decided answer to the second as well as
to the first of our questions. These facts are, first, that some species of Ascomycetes,
as has been already pointed out more than once, form their ascocarps only under
fixed and narrowly limited conditions, while they reproduce themselves by forming
gonidia under very varied conditions. Of this fact Penicillium, Peziza Fuckeliana,
Zopf’s Fumago, and the species of Hypomyces described above, are examples.
Secondly, there are pleomorphic species which also show a marked tendency to the
reproduction of like forms when the conditions remain unchanged, that is, each
spore-form chiefly produces its own form again, more rarely a form of another kind.
Peziza Fuckeliana is an excellent example of this. If the gonidia of this Fungus, the
spores of ‘Botrytis cinerea,’ are sown in a good nutrient solution, grape-juice for
instance, the product is always a filamentous mycelium with copious formation of
gonidia. If the ascospores are sown in the same solution under exactly the same
conditions, a mycelium is developed with sclerotia, but gonidiophores never or
scarcely ever appear ; wherever they have appeared they have appeared singly, and
cases of the kind are highly exceptional and not free from suspicion on the score of
the purity of the sowing. If similar sowings are made on suitable dead leaves of
Vitis or Castanea which have been boiled to free them as far as possible from
foreign spores, sclerotia are generally developed ; if ascospores are sown, sclerotia
only are formed without filamentous gonidiophores ; if gonidia are sown, the sclerotia
are accompanied by an abundance of gonidia which spring from the filamentous
mycelium. In cultures of the latter category single gonidiophores may certainly be
produced from a sowing of ascospores, just as they may be developed, as is well
known, from the sclerotia (see on page 224). The general result which is the

‘

CHAPTER V.—COMPARATIVE REVIEW.-—ASCOMFCETES. 255

important point here, the tendency to the reproduction of like forms, is not the less
manifest.

Similar relationships appear to exist in Pleospora herbarum (or Gibelli’s P.
Alternariae), but I cannot speak decidedly respecting them. By corresponding
relationships I should now be inclined to explain the facts, observed by myself
in connection with the reproduction of like forms in the gonidial form of Cor-
dyceps known as Isaria farinosa!, which led to a controversy respecting its con-
nection with the cycle of development of Cordyceps militaris, for which Tulasne
contended.

Moreover it must easily happen, that in species which show the tendency in
question, this tendency and the external conditions work together in the same
direction, and the possible consequences of this co-operation can be readily con-.
ceived. The long-continued effect of the combined conditions might ultimately result
“in the permanent separation of the originally connected forms, each preserving its
existence as a species. This means that each loses the other out of its cycle of
development, whether the other continues a separate existence or for any reason dis-
appears. It is quite conceivable that species of Ascomycetes producing gonidia only
like those described above might originate in this way,

On the other hand, we have to consider that the two sets of causes determining
the production of forms in these Fungi, the external and the internal, also work in
opposite directions, and that the external causes may eventually overcome the internal
tendency and lead to the reproduction of the other form from the one first produced.
We may also imagine a przorz that there are cases in which special conditions must
combine to produce this result, cases in which the few observations that we possess
do not acquaint us with the real conditions, though they are perhaps very simple.
Ten experiments may be made with a similar result under different conditions, and
the eleventh may all at once give a totally different result. Experiences of this kind
are quite common in this portion of the field of research. These facts admonish us
to be cautious, and require that the suggestions in the text should once more be
expressly declared to be only very guarded conjectures.

Section LXXIV. No less caution is advisable in determining some of the
organs which have been described above as doubtful, and we must say a word
more about them in this place. The attempt has more than once been made to remove
the doubt which exists as to their real nature by declaring them to be rudimentary
(rudimentär). It will be well therefore to remember that organs or members are
said to be rudimentary which do not reach the height of development attained by their
homologues but are stunted in their growth, that is, remain stationary at a stage in
their development in which they are in every respect immature; such are the
rudimentary stamens of Salvia and of some diclinous flowers. It is true that the term
rudimentary has been used in another sense, when an organ is highly developed,
but is not properly adapted to the function usually discharged by its homologues,
being applied to some other purpose through a necessity resulting from its high
organisation, as, for instance, the median staminode of Cypripedium. In some cases
this mode of expression may be obvious and therefore admissible, especially as there

1 Bot. Ztg. 1867, 1869.

256 DIVISION II,—COURSE OF DEVELOPMENT OF FUNGI.

are many gradations in the scale of arrestment and of perfection. Still it is more
correct in such cases to speak not of arrest of development, but of different adapfatıon,
or the metamorphosis of members, as we call foliage leaves, tendrils, and anthers in
their various adaptations metamorphosed leaves or phyllomes, but do not call foliage-
leaves rudimentary anthers, or anthers rudimentary foliage-leaves. At present we will
keep to the correct and customary usage and apply the term rudimentary to those
parts only which are arrested in respect to their development as members or
structures, and also as regards their capacity in every respect for discharging their
proper functions.

There is still another phenomenon which is allied in many points to unusual
metamorphosis and rudimentary development of members and yet is distinct from it,
namely, the occurrence of organs which are well developed and capadle of performing
their function, but which, as far as can be ascertained, are actually functionless. The
phenomenon is of course rare; but the antheridia and archegonia of the apogamous
Ferns! afford an example of its actual appearance among the organs of reproduction,
which, from the facts recorded elsewhere, may be considered as beyond doubt. The
occurrence therefore of this phenomenon must not be forgotten when we are-engaged
in deciding about doubtful formations.

The doubtful formations which we have to consider here are first of all the
‘doubtful sporocarps’ of the Aspergilli (and Sterigmatocystis of Van Tieghem),
and secondly most spermatia and spermogonia, The Aspergilli show exactly
the course of development of Penicillium. The doubtful sporocarps (p. 206)
are bodies that look like sclerotia and resemble the perithecia of Penicillium, but
differ from these, according to some observers at least, in that they show no
development of asci. Brefeld’s statements? to the contrary have been silently
withdrawn or ignored by himself? since the appearance of Wilhelm’s profound treatise
on the subject. The question then naturally arises, what was the reason for the
negative results respecting the formation of asci which were all that were obtained
during so many years? Brefeld answers the question by declaring these bodies to be
‘rudimentary primordia of perithecia.’ This may be so with the bodies which
Brefeld found in Aspergillus flavus and which he describes as undifferentiated tuber-
like structures. But Wilhelm repeatedly obtained from A. flavus as well as from
the other species a large number of well-developed bodies of the nature of sclerotia
which in A. flavus had a black rind; the development therefore goes in this
case also beyond the undifferentiated rudiment.

These bodies in view of their structure can no more be called rudimentary
than the sclerotia of Penicillium. The difference in structure which seems actually
to be found in all cases, namely, that there are no distinct ascogenous hyphae
such as appear in the sclerotia of Penicillium, cannot be of any importance, for this
difference exists in like manner up to the commencing formation of asci between
other primordial sporocarps, the perithecia of Claviceps and Pleospora for instance, on
one side and those of Melanospora and others on the other. It may be allowed that
these objections would be merely a playing with words, if there were sufficient grounds

1 See above, p. 122. 2 Bot. Ztg. 1876, p. 265. v
5 Schimmelpilze, IV, 134.

CHAPTER V.—COMPARATIVE REVIEW.—-ASCOMYCETES. 257

for believing that these bodies are /unctron/ess or discharge a very subordinate function.
But the known facts which may be summed up in the words structure of a sclerotium
and evident homology with Penicillium seem to be in favour of the contrary view, and
to show that the sclerotia in question are capable of development, and are stages
in the formation of ascocarps. The single argument for their being without
function, and therefore, as I am prepared to allow, for their being in a rudimentary
state, is to be drawn from the fact that no further development has been observed in
them during the two years that they have been known, and under the conditions of
cultivation which have been hitherto employed. On the other side it would be well to
remember our experience with other sclerotia and resting states, to simply acknowledge
our present ignorance and to give two more years to investigation before attempting to
decide the question. I have purposely referred here only to Brefeld and Wilhelm.
But Van Tieghem now asserts that he has actually obtained asci from Aspergillus
niger, in just the same way as from Penicillium. If this is confirmed, the whole
dispute is set at rest as far as that species is concerned, and the same thing will
happen probably in the case of the others also.

Many doubts, uncertainties, and controversies have also arisen in determining
the spermogonia and spermatia. Ido not include among these the many separate
cases more or less imperfectly investigated, in which it remains uncertain whether an
organ described as a spermogonium and assigned to a particular species really
belongs to that species or to some other which perhaps lives as a parasite in or with
the first species, and similar cases. To questions of this kind we may almost always
apply the remarks which will be found in a previous page respecting the determination
of the genetic connection between forms occurring together, and which are really
self-evident; we will only touch here on those cases in which the genetic connection
of the organs in question is certainly or as good as certainly ascertained.

We will fix our attention first of all on those spermatia only which are produced
from spermogonia and on the spermogonia themselves, remembering always that the
formation of spermatia differs in no essential point from that of acrogenously formed
spores, and that the one and always recurring distinction between the two organs is that
the spores germinate, while, as far as our observations go, the spermatia do not. The
spores germinate by the extrusion of a germ-tube, and it has either been actually
observed or it is assumed from analogy that the tube can grow into a mycelium.
Tulasne, the original discoverer of the spermatia and spermogonia, suggested in the
year 1851 that they were male sexual organs ; he rested his view partly on the non-
germination of the spermatia, partly on the fact that their formation usually precedes
that of the ascocarps, and in these points they certainly agree with the male
organs of other plants. It was clear from the mutual connection of the observed
facts, that it was the ascocarps and not the gonidial forms which must stand in
special and direct relation to the supposed fertilisation. Beyond this no certain idea
existed at the time of these first discoveries respecting the mode of fertilisation,
nor was anything known of the presumptive female organ which was supposed to be
fertilised. The discoveries which were needed to clear up these points have been made
from the year 1863 onwards.

Tulasne in his first works, and others after him, had described, under the name of
spermatia, some cells which resembled spermatia in their small size and in their origin,

[4] s

258 DIVISION II,—COURSE OF DEVELOPMENT OF FUNGI.

and had termed their receptacles or the organs that carried them spermogonia; but
it was shown by further observation that these cells were germinating spores or
gonidia, and that their receptacles should be termed gonidiophores or pycnidia, Of
a similar kind were the gonidia of Claviceps and other forms mentioned in Tulasne’s
Carpologia, which germinate very readily. As these observations multiplied, the
question naturally arose whether there really are spermatia which are absolutely with-
out the power of germination, or whether the absence of germination in the alleged
cases did not arise from defects in the mode of conducting the experiments, since
some spores only germinate under fixed conditions, and the conditions may not
always have been properly secured in the artificial cultivation of the plants. A work
of Cornu? endeavours to give an answer to this question, and a further answer is to
be found in Stahl’s treatise on Collema which appeared almost at the same time. The
two are very different.

Stahl’s work shows that there are spermatia which are not spores but fertilising
organs, and describes the mode of fertilisation and the organ to be fertilised (see
above on page 211). It does this, it is true, in a limited number of cases only; but
what is known of the rest of the Lichen-fungi, and is not disputed by Cornu, proves
further that by far the larger part of them possess spermatia which show no more signs
of germination than those of the Collemeae, and that these spermatia are homologous
with those of Collema. This is sufficient to distinguish the spermatia and spermogonia
from spores and their receptacles in this long series of cases, even though nothing
certain is yet known as. to the function of most of these spermatia. That exactly
the same condition of things is to be found also outside the group of Fungi which form
Lichens, is evident from the case of Polystigma described above on page 215.

Cornu, on the other hand, simply does not allow that the spermatia are special
organs, but would have them regarded as spores with the power of germination,
while retaining the name which they have hitherto borne. His arguments for this
view are not convincing. He saw first of all the ‘spermatia’ of certain species, which
hitherto perhaps had been considered to be incapable of germination or had not been
examined (for example those of Massaria Platani), produce germ-tubes when
sown in nutrient solutions; a few more therefore to be added to the previously
known cases of pseudo-spermatia. He also saw other known spermatia, those,
for instance, of Stictosphaeria Hoffmanni, Tul. and Valsa ambiens, Tul., undergo
changes of form, also in nutrient solutions, and swell up, but without showing further
signs of germination. He gives no other new facts; the cultivation of the spermatia
of Lichens gave him only negative results, and he can scarcely be said to have
advanced the subject even in a single minor point. His treatise was published
before the results of Stahl’s profound investigations were given to the world.

From the facts which have been established we now know of spermatia or
spermogonia in certain species or genera as organs with a definite function different
from that of spores. We can also form a plausible view as to the homology of these
bodies with the antheridial branches or functioning antheridia in other species which
have no spermatia, as was attempted to be done above on page 231. Lastly, we are
acquainted with a large number of species in which the homology of the spermatia

1 Reproduction d. Ascomycétes (Ann. d. sc. nat. ser. 6, III)

CHAPTER V.—COMPARATIVE REVIEW.—ASCOMPFCETES. 259

and spermogonia with those first mentioned is indubitable ; but, on the other hand, we
know nothing certain in almost all these latter cases about the function of the
spermatia. We may certainly assume that they are male fertilising organs in all the
species which possess an organ (trichogyne or ascogonium) which may be intended to
be fertilised. The swelling too of the spermatia in a nutrient solution, or even the
extrusion of a germ-tube, would not be an objection to this assumption, since
processes of growth might make their appearance, as Stahl has already remarked, in
this mode of cultivation, which in the natural course of development would only be
set up after contact with the organ to be fertilised, just as pollen-tubes are formed in
saccharine solutions. But, as was shown above, the female organs to be perhaps
fertilised are actually known only in a comparatively small number of species, and in
the rest, which are the large majority, the functions of the spermatia must therefore be
declared to be doubtful. If we suppose them to occur in species which have no
female organ, they cannot there have a sexual function. Yet we can hardly call them
rudimentary organs; and the enormous numbers in which they are produced are
opposed to the view that they are entirely without function: their function therefore
remains for the present undetermined.

Supposing after what has now been said that we have satisfied ourselves as to
the distinction between spermatia and small spores, and as to the mode of naming
them and their receptacles and so on, and can find our way in the practical description
of them, an interesting subject of enquiry still remains in the homological relations
between the two kinds of organs, for there is a striking agreement between them, not
only in form and structure, but also in that which is of much greater importance,
namely, the place or moment of their appearance in the course of the development.
In the latter respect, for instance, the commencing small-spored pycnidium of
Cucurbitaria Laburni agrees with the spermogonium of Polystigma or Physma.
Here we may say, without exaggeration, that the only difference lies in the germination.
In this and similar cases we only know the first products of germination, the germ-
tubes; we do not know what is developed from them. We might therefore consider
them to be formations which are incapable of further development, like the pollen-
tubes in a saccharine solution, or we might at least enquire if they are not of this
nature. However, we may put this point out of consideration and assume that
they are in all cases capable of producing a mycelium. This assumption does
not prevent us from maintaining their homology with true spermatia. On the
contrary, we may very well conceive that we are dealing witn homologues of different
adaptation or metamorphosis, and this different adaptation would arise in correlation
with the absence of the female organ capable of fertilisation; for, as far as we
can see at present, the phenomenon in question occurs exactly in those forms
which have no female organs, having lost them probably in the course of the phylo-
genetic development, as we have already endeavoured to show. It is no sufficient
objection that this metamorphosis of the spermatia is not found in all species that
have experienced this loss, for phenomena of this kind vary continually from species
to species.

The hypothesis that there are such metamorphosed spermatia would make many
facts more intelligible than they have hitherto been. It will depend on the results of
farther special investigations how far this hypothesis can be applied to small-spored

$2

260 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

pycnidia and similar formations, and we must not here enter further into the details of
the subject than the reader can at any time do for himself by comparing the examples
described in the preceding pages. But we may just observe that it is possible that
metamorphosis may be found in cases where it has been quite unsuspected. The
hymenium which has already been repeatedly described is found on the young stroma
of the Xylarieae, Claviceps, Epichloe, &c. either before or together with the first
appearance of the sporocarp, and gives off small cells, which in structure, origin,
and size might be spores (gonidia) or spermatia. There can be no doubt that they
are homologous in all these species. They were called gonidia in a previous page,
because they germinate in Claviceps and Epichloe, and in Poronia and Ustulina
among the Xylarieae ; but, as far as we know, they do not germinate in Xylaria—a fact
which may be added here to complete our former observations on the genus. These
phenomena find their explanation in the hypothesis here proposed, and may
therefore be brought forward in support of it; but it is obvious that the hypothesis
is not hereby made a certainty.

In conclusion we must recur again to the objects which were included in page 242
under the name of doubtful spermatia. The word ‘ doubtful’ must still be repeated
of many of them, for we possess only brief accounts of them, and portions of these
are disputed. I confine myself therefore to the cases of Sordaria, Chaetomium, and
Sclerotinia, which we know more in detail through the labours of Zopf and Brefeld.
Here, according to these observers, the organs in question agree as much in their
characteristic development and structure as in their power of germination under the
conditions to which they were submitted, and they have no other function, as far as
could be ascertained, than that of spores. They are therefore organs whose
function is unknown to us. It is osszble that they have no function at all; at any
rate as they do not function as sexual or otherwise reproductive organs, they can
scarcely have any important duties to fulfil, for they are usually few and small; and
if the case is otherwise in the specimens of Sclerotinia tuberosa grown by Brefeld, we
must not forget that in this instance the Fungus was growing under conditions quite
foreign to its usual circumstances. Having regard to the known facts and to the
analogies and homologies which may be applicable, there is the alternative proposed by
Zopf for the determination of these bodies, that they are either functionless spermatia,
or spores or gonidia not capable of germination. This is not a matter of indifference
in reference to the question of the homology. But gonidia without the power of
germination, according to all trustworthy data, are things which nothing but
extreme necessity can allow us to assume; and in the case of the Chaetomieae,
where, according to Zopf, almost every cell of the mycelium may becomea gemma
or gonidium with power of germination, and in Sclerotinia Fuckeliana with its
characteristic and highly reproductive gonidiophores, it would be an absurd thing
that such well-furnished appliances should be occupied solely in producing sterile
gonidia. But if we suppose these bodies to be homologous with spermatia, the
whole matter becomes intelligible from the points of view which have now been
discussed. Only one objection has been brought forward to this view. Brefeld?
calls attention to the difficulty of accounting for the concurrence in ‘Sordaria’ of

! Schimmelpilze, IV, p. 143.

CHAPTER V.—COMPARATIVE REVIEW.—ASCOMFCETES. 261

spermatia with or without special functions and an antheridial branch which
conjugates with the archicarp. But the ‘Sordaria’ in which the antheridial branch
has been observed is Sordaria or Hypocopra fimicola described by Gilkinet, and
spermatia are not said to have been found in it. The Sordarieae in which the
spermatia in question have been found are different species, S. curvula, S. minuta, and
others!, and it has not been shown that their young sporocarp is like that of
S. fimicola. On the contrary, it has been already intimated on page 235 that there
appear to be important differences in the matter of the inception of the sporocarp
in the group of the Sordarieae. Brefeld’s objection therefore rests on a misconception,
and is at present at least not justified ; and if it is removed, it is no longer necessary
to consider at length the question of the connection between these cases and those
discussed above in which the spermatia were supposed to be without sexual
function.

Literature of sections LIX-LXXIV.

VITTADINI, Monogr. Tuberacearum, Mediolani, 1831.

TULASNE, Fungi hypogaei, Paris, 1851 ;—Id., Selecta Fungorum Carpologia, I-III,
Paris ;—Id., Recherches sur l’organisation des Onygena (Ann. d. sc. nat. sér. 3, I,
1844) ;—Id., Note sur l’appareil reproducteur des Lichens et des Champignons
(Ann. d. sc. nat. ser. 3, XV, 1851) ; see also Compt. rend. XXXII, p. 470 ;—Id.,
Mémoire pour servir 4 P’histoire organographique et physiologique des Lichens
(Ann. d. sc. nat. ser. 3, XVII) ;—Id., Discomycétes (Ann. d. sc. nat. ser. 3, XX,
p- 128) ;—Id., Mém. sur l’Ergot des Glumacées (Ann. d. sc. nat. ser. 3, XX, p. 5) ;—
Id., Note sur l'appareil reproductive d. Hypoxylées et d. Pyrénomycétes (Ann. d.
sc. nat. sér. 4, V, p. 108) ;—Id., Nouvelles obs. sur les Erysiphées (Ann. d. sc. nat.
ser. 4, I, 299, and Bot. Ztg. 1853, p. 257) ;—Id., Notes sur les Isaria et les Sphaeria
entomogénes (Ann. d. sc. nat. ser. 4, VIII, p. 44) ;—Id., De quelques spheries
fongicoles (Ann. d. sc. nat. sér. 4, XIII, p. 5); see also Comptes rendus, 41,
p. 615 and 50, p. 16;—Id., Note sur les phénoménes de copulation dans les
Champignons (Ann. d. sc. nat. sér. 5, V, p. 216).

CURREY, On the fructification of certain Sphaeriaceous Fungi (Philos. Trans. Royal
Soc. London, 147, 1858).

DE Bary, Ueber d. Fruchtentwicklung d. Ascomyceten, Leipzig, 1863 ;—Id., Eurotium,
Erysiphe, Cicinnobolus, nebst Bemerkungen ii. d. Geschlechtsorgane d. Ascomy-
ceten (Beitr. z. Morph. u. Physiol. d. Pilze, III, Frankf. 1870). See also Beitr. IV,
p. III.

S. SCHWENDENER, Ueber d. Entw. d. Apothecien von Coenogonium (Flora, 1862, p. 224);
—Id., Ueber d. Apothecia primitus aperta u.d. Entw. d. Apothecien im Allgemeinen
(Flora, 1864, p. 320).

FUISTING, De nonnullis Apothecii Lichenum evolvendi rationibus (Diss. inaugur.

Berol., 1865) ;—Id., Zur Entwicklungsgesch. d. Pyrenomyceten (Bot. Ztg. 1867,
1868) ;—Id., Zur Entwicklungsgesch. d. Lichenen (Bot. Ztg. 1868).

WoRrONIN, Entwicklungsgesch. d. Ascobolus pulcherrimus u. einiger Pezizen (Beitr. z.
Morph. u. Phys. d. Pilze, II). Id., Sphaeria Lemaneae, Sordaria, &c. (Beitr. z.
Morph. u. Phys. d. Pilze, III).

JANCZEWSKI, Morph. d. Ascobolus furfuraceus (Bot. Ztg. 1871, p. 257).

1 Zopf, Chaetomium, p. 237.

v

262 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

J. KUHN in Mittheil. d. Landw. Instit. Halle, I, 1863 (Claviceps).

O. BREFELD, Bot. Unters. ii. Schimmelpilze, II (Penicillium) IV. _

VAN TIEGHEM, Comptes rendus, 81, 1875 (Chaetomium) ;—Id., Nouvelles Observ. sur
le développement du fruit, &c. des Ascomycétes (Bull. Soc. Bot. de France, 23,
1876, p. 99); see also Bot. Ztg. 1876, p. 165;—Id., Sur le devel. du fruit des
Ascodesmis (Bull. Soc. Bot. de France, 23 (1876), p. 271 ;—Id., Nouvelles Obs. s. 1.
dével. du périthéce des Chaetomium (Bull. Soc. Bot. de France, 23, 1876) ;—Id.,
Sur le dével. de quelques Ascomycetes (Aspergillus), (Bull. Soc. Bot. de France, 24,
1877).

GILKINET, Rech. s. 1. Pyrénomycétes (Sordaria), (Bull. Acad. Belg. 1874).

BARANETZKI, Entw. d. Gymnoascus Reesii (Bot. Ztg. 1872).

EIDAM, Beitr. z. Kenntn. d. Gymnoasceen in Cohn’s Beitr. z. Biol. III, 271;—Id.,
Z. Kenntn. d. Entw. d. Ascomyceten in Cohn’s Beitr. .. Biol. III, 377 ;—Id., Ueber
Pycniden (Bot. Ztg. 1877). ;

E. STAHL, Beitr. z. Entwicklungsgesch. d. Flechten, I, Leipzig, 1877.

A. BORZI, Studii sulla sessualita degli Ascomicete (N. Giorn. Bot. Ital. X (1878), p. 43).
BAINIER in Bull. Soc. Bot. de France, 25, 1878.

C. Fiscu, Zur Entwicklungsgesch. einiger Ascomyceten (Bot. Ztg. 1882).

O. KIHLMAN, Zur Entwicklungsgesch. d. Ascomyceten (Pyronema, Melanospora) in Act.
Soc. Sc. Fennicae, XIII, Helsingfors, 1883.

W. ZoPpF, Zur Entwicklungsgesch. d. Ascomyceten (Chaetomium), (N. Act. Leopold.
XLII, 1881) ;—Id., Die Conidienfrüchte v. Fumago (N. Act. Leop. XL, 1878).

GIBELLI e GRIFFINI, Sul polymorphismo della Pleospora herbarum (Archiv. del
Laborat. di Bot. Crittogam. in Pavia, I (1873), p. 53).

H. BAUKE, Zur Entwickelungsgesch. d. Ascomyceten (Bot. Ztg. 1877, 313) ;— Id., Beitr.
z. Kenntn. d. Pycniden (N. Act. Leop. XXXVIII, 1876).

K. WILHELM, Beitr. z. Kenntn. d. Pi:zgattung Aspergillus (Diss. Berlin, 1877).

O. MATTIROLO, Sullo sviluppo e sullo sclerozio della Peziza Sclerotiorum, Lib. (N. Giorn.
Bot. Ital. XIV, 1882), p. 2.

B. PIROTTA, Sullo sviluppo della Peziza Fuckeliana, &c. (N.Giorn. Bot. Ital. XIII, 1881),
p- 130.
G. KRABBE, Entw., Sprossung u. Theilung einiger Flechtenapothecien (Bot. Ztg. 1882,

Nr. 5-8) ;—Id., Morphol. u. Entwicklungsgesch. d. Cladoniaceen (Ber. d. deutsch
bot. Ges. 1883).

REINKE u. BERTHOLD, Die Zersetzung d. Kartoffel durch Pilze, Berlin, 1879.

R. WOLFF, Beitr. z. Kenntn. d. Schmarotzerpilze (Erysiphe) in Thiel’s Landw. Jahrb.
1872 (?). :

M. CORNU, Reproduction d. Ascomycétes (Ann. d. sc. nat. sér. 6, III).

R. HARTIG, Wichtige Krankh. d. Waldbäume, p. 101 (Hysterium) ;—Id., Unters aus d.,
Forstbot. Inst. z. Miinchen, I (Rossellinia, Nectria).

W. LAUDER LinpDsay in Trans. Roy. Soc. Edinburgh, I, p. 101. (Spermogonia and
‘stylospores’ of Lichens.) :

GIBELLI, Sugli org. reprod. del gen. Verrucaria (Mem. Soc. ital. di Scienc. nat. 1).

A. MILLARDET in Mem. de la Soc. d’hist. nat. de Strasbourg, VI, 1868. (Myriangium,
Naetrocymbe, Atichia.)

See also the works quoted in the foot-notes to the text.

es

CHAPTER V.—COMPARATIVE REVIEW.—DOUBTFUL ASCOMYCETES. 263

The reader is also referred to descriptive and phytopathologicalliterature. Nylander’s
Synopsis is specially valuable among works on the Lichen-fungi ; others will be found
fully given in Von Krempelhuber’s Geschichte u. Literatur d. Lichenologie.

DouUBTFUL ASCoMYCETES.

Section LXXV. There are certain small groups of Fungi which, as far as we
know them, show a greater amount of agreement with the Ascomycetes than with any
other Fungi, and must therefore
be classed with the Ascomy-
cetes. Some, like the Laboul-
benieae and the group formed
of Exoascus and Saccharomy-
ces, have asci, but are so widely
separated by structure and
course of development from
typical Ascomycetes, that there
may be some scruple about
uniting them directly with this
division of the Fungi; others
greatly resemble certain typical
Ascomycetes in all that is as-
certained of their life-history,
but are hitherto only known to
produce peculiar small cellular
bodies, ‘ bulbils,’ without power
of germination, instead of spo-
rocarps with asci.

Tothe lattercategory belong
the forms Helicosporangium
parasiticum, Karst., and Pa-
pulaspora aspergilliformis,
Eid., which have recently been
described by Eidam. We can
only mention them thus briefly

FIG. 120. 4, b—h Stigmatomyces Baeri, Peyritsch (St. Muscae, Karsten).

in this place, referring thereader
to Eidam’s publication; the
plants themselves should be
further investigated. We pro-
ceed to give a short account of
the other species.

Most ofthe Laboulbenieae
grow on the outer surface of

4 ripe specimen with its black organ of attachment released from the skin of the
fly, showing the surface and an optical longitudinal section; the asci are seen
through the wall of the perithecium. a everywhere the appendage. d an isolated
ascus with ripe spores. c—h of the p i and appendage ;
ive stages of d ding to the letters. c two double spores
fastened to the wing ofa house-fly. @, e older states on the chitinous membrane cut
h h per dicularly. 2 of the perithecium. g the delicate
Projection (? trichogyne) from the apex of the perithecium, with the small round
swellings on the ities of the b 'h dag A after the
formation of the perithecium is d. Zfull-g i of Laboulb,
JStagellata, Peyr. from the wing of Be di: I: The stalk-like
base of a second specimen is indicated, with the same black organ of attachment.
a the appendage, All the figures after Peyritsch. A «, g, A magn. 350, dd,e,f
450, B 125 times.

beetles which live in or near water, but some are found on other insects, as the species
especially of Eastern Europe, Stigmatomyces Baeri, Peyr., which is common in Vienna
on house-flies. They appear like small brushes on the surface of the insect, either
singly or often, like Stigmatomyces, forming a thick fur on it, Each of these

264 DIVISION II,—COURSE OF DEVELOPMENT OF FUNGI.

small brush-like bodies is a separate plant. The entire lengih in the largest known
species, Laboulbenia Nebriae, is about ı mm., in most species little or not more
than o'5 mm. The phenomena observed in them most nearly resemble those known
in the Ascomycetes, and are named accordingly. The small plant (Fig. 120) is
attached to the substratum by a filiform or clubshaped stalk, consisting usually of
two cells one above the other; at the apex of the stalk is a perithecium and a body
which may be here briefly termed an appendage (a). The perithecium is narrowly
conical in form or flask-shaped and in some species oblique, and consists when
mature of a wall formed of a few cells disposed in two layers at the base and one
layer at the sides with a narrow orifice at the apex; the group of asci which rises
erect from the base of the perithecium is closely surrounded by its wall. The number
of the asci and the way in which the spores are formed in them are not exactly
ascertained. The number of spores in an ascus is said to be 8 and 12; the ripe
spores are fusiform and colourless, and being divided by a transverse wall into two
equal cells are therefore compound and bicellular; they escape singly and one after
another through the orifice of the perithecium, no doubt in consequence of the
gelatinous deliquescence of the wall of the ascus. The appendage springs from close
to the base of the perithecium in the form of a segmented hair or filament, varying,
according to the species, in length and number of cells and presence or absence of
branches, which in some species are very peculiar in their form and arrangement.
All the cells in the mature Fungus except the asci, the spores, and the extremities of
the branches of the appendage, have very thick membranes of a deep and often a dark
brown colour. :

The Laboulbenieae have no mycelium; the ripe double spore attaches itself by
one extremity to the chitinous covering of the insect, and sends into it a small short
point, which sometimes enlarges into a knob at its extremity and with the surrounding
chitin soon assumes a brown colour; this point is its only organ of attachment and
of nutrition. Thus firmly planted it developes at right angles to the substratum and
reaches its mature state by the necessary successive cell-divisions and differentiations.
Most of the details of these formations can be seen at once in the accompanying figure
for the case which it represents, but some important points have still to be cleared up.
I select the following for special notice, and refer the reader to Peyritsch’s treatises for
further details. The appendage is developed from the cell of the double spore which
is the upper one in reference to the point of attachment; it is therefore originally
terminal and is completed before the perithecium. The stalk and the perithecium
are formed from the Zower cell of the double spore; the perithecium shoots out laterally
from beneath the point which is afterwards that of insertion of the appendage, and
as it increases in breadth it thrusts the appendage to one side. In its earliest stage it is
unicellular; as it grows it divides by successive transverse divisions into three tiers of one
cell each, and each tier in acropetal succession then separates by longitudinal division
into an axile and several parietal cells. But before the longitudinal division begins
(Laboulbenia vulgaris), or before it has reached the uppermost tier-cell (Stigmatomyces),
it is observed that this cell puts out a short protuberance at its apex, which is either very
thin-walled or seems to have no membrane, and disappears again at a later stage of the
development (Fig. 120 g, 4). Simultaneously with the formation of this protuberance on
the primordium of the perithecium small thin-walled swellings are seen on the apex or

CHAPTER V.—COMPARATIVE REVIEW.—DOUBTFUL ASCOMYCETES. 265

on the tips of the branches of the young appendage, and these also subsequently dis-
appear. According to Karsten these small swellings, which are spherical in Stigmato-
myces, separate in that plant from the cells on which they are formed and attach
themselves to the protuberance on the young perithecium, as spermatia in the Fungi
or Florideae attach themselves to the trichogyne, and then the spores or asci are
developed from an axile cell. If this were so, the organs in question would have to be
termed sexual organs and their homologies with the sexual organs of the Ascomy-
cetes would be evident enough. But it appears from Peyritsch’s careful observations
that no such supposed abscision of spermatia really takes place. We know nothing
more than has been stated above, and Peyritsch himself does not think very highly
of his own attempt to save the trichogyne, which might be fertilised by contact with
a young branch from the appendage. It is not yet quite certainly ascertained
whether the asci are formed by division or by sprouting from one or more initial cells.
With these data only to guide us, it will be best for the present to allow the
remarkable little group to remain next the Ascomycetes, being marked as doubtful,
till further information is obtained concerning them.

Section LXXVI. The species of Taphrina, Fr., the Exoascus of Fuckel
in Sadebeck’s sense‘, are parasites developing on the surface of parts of living
plants, which are more or less deformed by them; Exoascus Pruni, for example,
grows on the young fruit of species of Prunus, and produces swellings in them which
are known as pockets, more rarely on the leafy shoots, while E. aureus is found on
the leaves and ovaries of Poplars and Aspens and E. alnitorquus on the deformed
fruits and upon leaves of the Alder.

The Fungus when fully developed is composed chiefly of a single palisade-like
layer of asci standing close beside one another, which breaks through the cuticle and
covers the outer surface of the epidermis of the part attacked. The species which
live on the Amygdaleae, Exoascus Pruni for example and E. deformans, develope
this layer from a filiform mycelium, which first spreads in the inner parenchyma of
the part and then thrusts its branches in between the outer walls of the epidermal
cells and the cuticle. In this situation the branches ramify copiously, and spread
out in the direction of the surface, the ramifications, which grow alongside and
between one another, forming a single layer and then becoming divided into
isodiametric cells. Each of these cells next swells into a vesicle, and breaking
through the cuticle elongates in a direction perpendicular to the substratum and
becomes club-shaped, and at length divides by a transverse wall into a lower cell,
the short szalk-cell, which rests on the substratum, and an upper cell, the club-
shaped ascus. The connection of the ascus-layer thus formed with the intra-
matrical mycelium can be seen even when the asci are mature.

Other species, Exoascus alnitorquus for instance and E. aureus, according to
Sadebeck’s and to some extent also of Magnus’ earlier investigations, spread their
mycelium only between the cuticle and the epidermis. Then, as the plant developes,
all the hyphae become divided into ascogenous cells, and these proceed as in E. Pruni;
consequently asci only are to be seen when the fructification is mature, and these
are either borne on a stalk-cell (E. alnitorquus) as in E. Pruni, or have no stalk

1 In Winter, Pilze, II.

266 DIVISION II,—COURSE OF DEVELOPMENT OF FUNGI.

(E. aureus). In the latter case especially and in the last-named species the outer
extremity of each ascus bursts through the cuticle, while the inner extremity grows into
a narrowly conical process, which becomes deeply and firmly fixed between the lateral
walls of the epidermal cells. The forms of a third series, represented by Sadebeck’s
Exoascus epiphyllus, which grows on Alnus incana, and E. Ulmi, also spread their
hyphae between the cuticle and the wall of the epidermal cells, but form their asci
from a part only of their cells, while the other part remains sterile; hence the asci are
here less crowded.

The structure of the asci, the formation of the spores in them, and the ejection of
the spores by mechanical contrivance, are essentially the same, as far as is at present
known, as in other organs of the same name. The number of the simultaneously
formed ascospores is also usually eight in Exoascus Pruni; other numbers will be
mentioned further on. All the spores are small, simple, ellipsoidal cells with a delicate
colourless membrane.

.The spores of Exoascus Pruni are ejected when ripe and germinate at once in
water or a nutrient solution, sprouting repeatedly and perfectly and forming many
orders of sprouts. Those of the first orders are of much the same shape and size as
the mother-spore, those of the higher are often much smaller. If the ripe spores
are detained in the ascus, they often form their germ-sprouts in it, and the ascus
becomes filled with countless sprouts of different orders and sizes, which readily
separate from one another and escape as individual ‘spores’ when the ascus
opens.

The spores germinate in a very similar manner in the other species. In many
of them, those for instance which live on Poplars and Alders, a very large number of
small sprouting spores are found in the ripe ascus. Sadebeck states that these are
always sproutings from eight primary ascospores; according to my earlier researches
and Brefeld’s investigations, repeated quite recently, the original spores in Exoascus
Populi may be less than eight; Brefeld says that there are usually four, and I
remember to have seen only two and three. Short germ-tubes, which soon give
off sprout-cells, are occasionally formed from the spores, as, for example, in E.
alnitorquus.

Sadebeck has noticed that the products of the germination of the spores of
Exoascus alnitorquus and E. bullatus penetrate into young leaves of Alnus glutinosa
or Pyrus communis, and there develope directly into ascogenous hyphae. The mode
of penetration is not stated. This observation would justify our assuming a similar
behaviour in the other species, with the addition that in some of them at least the
mycelium vegetates and maintains itself for a long time in the plant which it attacks.
For instance, it is found early in spring in the rind of the branches of Prunus and
spreads from them into the young twigs and fruits; and in E. deformans, which
inhabits the cherry-tree, it is perennial and lives for years in the rind of the branches,
where it causes the ‘ witches’ brooms,’ and sends branches every year to form asci in
the leaves, which are disfigured in a similar manner.

There is another doubtful Fungus which Reess has named Endomyces
decipiens, and which must for the present be placed near Exoascus. It grows in
old lamellae of Agaricus melleus and consists of septate hyphae, which are often
constricted at the septa and produce small ellipsoid asci arranged in lateral clusters.

CHAPTER V.— COMPARATIVE REVIEW.—DOUBTFUL ASCOMYCETES. 267

Four hemispherical spores are formed in each ascus, which escape when mature by
the dissolution of the wall of the ascus, and put out germ-tubes in water. Nothing
more is known of this species; the controversy which has arisen in the attempt to
determine it will be noticed again in section XCIII.

Section LXXVII. The chief representatives of the genus Saccharomyces
are the Yeast-fungi which excite alcoholic fermentation and are known as Sac-
charomyces Cerevisiae, S. ellipsoideus, S. Pastorianus, &c. These names, according
to E. Hansen’s recent investigations, denote form-groups, which will no doubt have
to be otherwise distributed. Besides these there are the Flowers of wine, S. Myco-
derma, Reess, Cienkowski’s Chalara Mycoderma, and the Fungus of thrush (apthae),
S. albicans, Reess, which grows as a parasite on the mucous membrane of the
human digestive organs, but also thrives in saccharine fluids, where it excites a slight
fermentation. The rest are found in quantity in or on fluids which are fermenting
or have undergone fermentation. S. Cerevisiae is added intentionally to the wort of
beer and is cultivated largely for this purpose. Other kinds and indeed S. Cerevisiae
as well appear of themselves in must, finding their way into it chiefly from the
surface of the juicy fruits which yield the must.
They are conveyed to these fruits along with
dust from the surfaces of other bodies (see be-
low, section C).

The larger part of these Fungi vegetate,
as far as we know, only by sprouting (Fig. 121).
Continuous branching hyphae with long seg-
ments are found only in Saccharomyces
albicans, in S. Mycoderma and Cienkowski’s
Chalara; these grow directly, according to
Cienkowski’s observations on S. Mycoderma, | FIG. 121. Saccharomyces Cerevisiae. a cells before

sprouting. &—d cells sprouting in a fermenting saccharine

from cells formed by sprouting, produce fresh ee ee development according to
cells from their sides by sprouting, and ulti-
mately divide transversely into short cells which then vegetate simply by sprouting. Other
species, especially Reess’ S. Pastorianus, show a certain approach to this growth-form in
that they are frequently chains of elongated sprout-cells, from which short cells are
abscised laterally. The shape moreover of the single sprout varies generally between
spherical and elongated cylindrical, with certain rules and limitations in each species.
The cells that are formed one after another by sprouting in the fermenting fluid are
usually at once separated from one another; connected strings of cells are to be seen
when the plant vegetates on still surfaces, such as a microscopic slide especially, and
the length and number of the chains vary according to the species. The cells of
S. Cerevisiae, when developed in large quantities, often adhere together irregularly
and form largish lumps, being attached to one another apparently by the muci-
laginous outer lamellae of their membranes (see on page g). The structure
of the sprout-cells is that of other vegetative fungal cells, but their membranes are
comparatively thin and colourless.

The Saccharomycetes in the sprouting form may be said to be capable of
unlimited growth and multiplication if supplied with sufficient food. This is shown
by the hundreds of thousands of pounds weight of yeast which are produced year by

268 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

year and which consist entirely of the sprouts of S. Cerevisiae. But a certain number
of known species also forms spores in ascı under certain conditions ; this fact was dis-
covered by DeSeynes in Saccharomyces Mycodermain, 1868, was afterwards examined
more thoroughly especially by Reess, and has now been certainly established in S.
Mycoderma and the forms included under the names of S. Cerevisiae, S. ellipsoideus
and S. Pastorianus. It occurs most readily and most frequently in the S. ellipsoideus
of wine-yeast. It has been studied by Reess, Hansen, and other observers in S.
Cerevisiae, but it is often difficult to induce this cultivated form to produce spores.
Spores begin to be formed if well-fed specimens, protected as far as possible from
invasion by other Fungi and Schizomycetes, are kept without food or restricted to the
least possible amount of it in presence of water and air containing free oxygen and
in a suitable temperature; if, for example, yeast is spread in a thin layer on moist
surfaces, such as succulent parts of plants, plaster of Paris, or a microscopic slide, or
kept in a little distilled water. At first new cells are formed by sprouting in such
cultures at the expense of the old ones, which may become exhausted and sometimes
die. Then spores are formed in cells which are not distinguished by their origin,
shape, or any other particular, sometimes in a few isolated cells, at other times in all
or most of the cells of a chain. Two or four, or some-
times three, seldom more than four spores are formed in
a cell according to its size. The stages observed in the
formation of the spores correspond to the processes
known to occur in asci (see section XIX). The young
spores appear simultaneously as delicately circumscribed
round bodies of homogeneous protoplasm collected into
a group inside the protoplasm of the mother-cell, in
FiG.122. Sacchavomyceseltipsoideus, Which a parietal layer of protoplasm remains at first
R. (Wine-yeast). Formation of spores n
E man ulm ee everywhere unbroken (Fig. 122). The spores soon form
six hours on a microscopic slide in dis. a Membrane which always remains thin, and increase
fully formed. Magn about wotimer in volume while the protoplasm more or less completely
disappears. When full-grown they may just fill the cavity of
the mother-cell, but generally they do not quite fill it; if they are four in number they
are disposed tetrahedrally as quadrants of a sphere or in a row according to the shape
of the cell. They are now arrived at maturity. In older specimens the membrane of the
mother-cell often collapses and disappears; it is ruptured according to Cienkowski’s
account in Saccharomyces Mycoderma and releases the spores. The ripe spores can
germinate as soon as they enter the nutrient fluid. In germination they swell slightly
and form vacuoles, and then begin to sprout in the manner proper to each species ;
the membrane of the mother-cell is broken through as the first sprouts are extruded.
E. Hansen found in the species which he examined sprout-cells which were
divided by thick flat partition-walls into 2-4 daughter-cells, and these cells germinated
in the same way as the ascogenous spores, but he did not see the formation of these
septa. Meanwhile, judging from the figures, we should be inclined to suspect that the
formations in question are simply asci with their walls much collapsed after ripening
and with the spores closely pressed one against another.

The foregoing brief account of the formation of the spores of the Saccharomycetes
is taken from Reess’ earlier statements and a recent revision of them in examining

CHAPTER V,—COMPARATIVE REVIEW.—DOUBTFUL ASCOMYCETES. 269

Saccharomyces ellipsoideus; it would appear to be an evident case of partial
division or free cell-formation (see page 61), in which the observed facts perfectly
correspond to what is known of the formation of spores in smaller asci (Exoascus,
Eurotium). The term asci is accordingly chosen or retained. It is true that there
are differences of opinion with regard to the process in question. Cienkowski suspects
that in S. Mycoderma the whole of the protoplasm of the mother-cell is divided
into spores, and Brefeld speaks in the same way as regards other species, (‘ wine-yeast’)
in so far as he considers the sporogenous process in Saccharomyces to be like that in
Mucor, regarding the latter indeed as a case of partial division. It is otherwise in the
Saccharomycetes examined by Reess and myself. The continued presence of the
parietal layer of protoplasm after the formation of the spores is decisive in their case
even now, when the distinction between ‘free cell-formation’ and (total) division is
less sharp than it once was. The spores are not formed in the sporangia of
Mucor in the same way as in Saccharomyces (see page 74). Lastly, Van Tieghem
has proposed a view which differs entirely from any other‘. He thinks that the
spores of Saccharomyces are produced by the division of the whole of the protoplasm,
but that they are pathological formations induced by the assaults of Bacteria ; this idea
was suggested by the behaviour of spores of Mucor in presence of Bacteria, but it is
at once refuted by the observation of a good specimen grown beneath the microscope
in distilled water and free from Bacteria, and appears to have been recently abandoned
by its author”, ,

Section LXXVII. There can be no doubt, from what we know of the history
of development in the ascogenous Saccharomycetes, that they are immediately
connected morphologically with the Exoasci. The differences in form between them
and the Exoasci, whose hyphae are broken up into asci, would even allow of the
two groups being united into one genus. The two genera therefore together form
a natural group, which may be called here the Exoascus-group.

If we enquire further into the connection of this group with other Fungi, we can
only take morphological arguments into consideration in determining the question.
No decisive argument of the kind is to be drawn from the simple vegetative structure ;
the tendency to vegetate by sprouting or the actual occurrence of this mode of vege-
tation in Saccharomyces cannot determine anything, for this phenomenon occurs in
the most heterogeneous fungal groups, as has been already pointed out and will be
again noticed below. But our group forms asci, and this peculiarity it shares only
with the Ascomycetes, if we disregard Protomyces, which, however, is much further
removed from it (see p. 171), and this must be decisive at present for its connection
with the Ascomycetes. Brefeld’s early opinion, expressed in the year 1876, that
Saccharomyces belongs to the Mucorini was disposed of when it was shown that
the chief argument in its favour drawn from the similarity in the mode of spore-
formation cannot be maintained.

The connection with the Ascomycetes rests entirely on the resemblances which
have been pointed out between the two groups. It remains uncertain how far these
resemblances are the expression of natural and phylogenetic affinity. That they are
the results of such an affinity is rendered highly probable by the great agreement
between the hymenia of the more highly differentiated Exoasci and typical Ascomy-

x

' Ann. d. sc. nat. ser. 6, IV, p. 9.
2 Traité de Botanique.

270 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

cetes. Objections to this view are drawn from the entire absence of archicarp and
ascogonium and differentiation of ascus-apparatus and envelope-apparatus. But we
have constantly seen variations in the amount of differentiation in these organs
within the group of the Ascomycetes, and can therefore conceive of an extreme
simplification; we must perhaps wait for the discovery of more thoroughly inter-
mediate forms.

If without waiting for more exact proof we assume a phylogenetic connection ®
between the Exoascus-group and the Ascomycetes, two views are open to our
adoption. Either the former group represents the simple s/arting-point of the series
of Ascomycetes, the Saccharomycetes containing the simplest forms from which
Ascomycetes have been gradually developed; or its members are greatly reduced
Ascomycetes (see page 125), with extensively interrupted homology which is only
restored with the appearance of the asci. The latter is the only admissible assump-
tion if the account given above of the relation of the Ascomycetes to the Phycomycetes
by affinity and descent is the true one, and it must be maintained with the necessary
reservation so long as these relations, which are the natural conclusion from known
facts, are not set aside by the discovery of new ones.

Most of the species of Saccharomyces which have been mentioned above are
the most common and practically the most important inciters of alcoholic fermentation ;
they are the yeasts of fermentation and are for this reason generally termed Yeast-
fungi. Some of them, beer-yeast for example, are purposely added to the liquid
which is intended to ferment; the juices of certain fruits ferment spontaneously, the
yeast-plants appearing in them without artificial assistance. This led the earlier
observers to the notion, which afterwards reappeared from time to time, that the
Yeast-fungi are formed without parentage from the organisable material contained
in the juices of fruit. Karsten! in 1848 derived them from organised ‘vesicles,’
which had been normal parts of the cells of living plants and continued to vegetate inde-
pendently after their death. But ideas of this kind have been given up for many years.
We now know that the Yeast-fungi are derived from parent-forms as members of
the development of a normal species of Fungus, and that their germs find their
way from without into fermentable fluids ; this latter point will be noticed again in
a subsequent chapter. But those who upheld this view carried on a lively controversy
respecting the systematic or morphological relations of the Yeast-fungi, especially
before the asci of Saccharomyces had been observed by De Seynes and Reess in
1868 and 1870. Some writers regarded them as independent representatives of
distinct species which always appear in the form of sprouting Fungi (Schwann,
Pasteur, De Bary). Others, on the contrary, considered them to be special forms of
species of Fungi which are generated in suitable fluids, and which appear in some other
form, chiefly that of the Hyphomycetes, outside these fluids; they thought that the
characteristic sprouting form of the plants and the yeast-fermentation depended on the
nature of the medium, and that the Fungus could be brought back again to the other
form, the Hyphomycetous form for example, by changing the medium. Either some
particular species were indicated as capable of this transmutation, chiefly the common
Moulds, species of Mucor for example, Sclerotinia Fuckeliana (Botrytis cinerea) (Bail) or
Penicillium (Berkeley), or the capacity was supposed to exist in a great variety of Fungi,
though here again the commonly diffused species just named stood at the head of the
list (H. Hoffmann). ‘

Continued investigations have brought to light the reasons for this variety of

' Bot. Ztg. 1848, p. 457-

CHAPTER V.—COMPARATIVE REVIEW.—DOUBTFUL ASCOMPCETES. 271

opinion. They have shown that the earlier observers obtained uncertain results
from having different and imperfectly distinguished forms mixed up together in
their impure cultures, and have revealed another source of obscurity in their belief
that every form of sprouting Fungus must be regarded as an inciter of fermentation
or ‘Yeast-fungus,’ and conversely that all alcoholic fermentation was caused by the
vegetation of a sprouting Fungus resembling Saccharomyces. We know now that
this is not so.

But there are j7s of all many species of Fungi in which the,only mode of vegetation
is by sprouting or which vegetate in this way under certain circumstances or in certain
stages of their development. Foremost among these are the ascogenous species of
Saccharomyces. Connected with the latter are the forms which resemble them
exactly in their vegetative construction, but in which asci and distinct spores are not
known, or it should be said perhaps are not yet known. These are usually, and for
the present rightly placed in the genus Saccharomyces ; whether they really belong
to it has yet to be ascertained; Among them are S. apiculatus which has been
so thoroughly examined by E. Hansen, and ‘Pasteur’s Torulae’ recently investi-
gated by the same observer. To these must be added Exoascus, also the plants
mentioned above on page 114 as examples
of germination by sprouting, and certain
Mucorini (see page 155) with further in-
stances in the Ustilagineae (see page 179),

Tremellineae, and Exobasidium recently A

supplied by Brefeld (see section XCII).

Lastly, we must mention Fumago (see

page 249) on Zopf’s authority, and a form

most probably nearly related to Fumago

or Pleospora and at present imperfectly

known, which I formerly described as x

Dematium pullulans. It is very com-

mon on the surface of plants; and for

this reason and because its sprout-cells

are very like those of some species of

Saccharomyces the two forms have no

doubt often been mistaken for one another EEE BEER NER oe ert

by earlier observers, who did not distin- of cells with brown membranes forming tubes and occasionally
= “ & sprouts in a saccharine solution. 2 portion of a filament

guish different forms very acutely. It is vegetating in a saccharine solution and covered with sprout-

probable that a similar confusion is at the el. 4 magn. 390, 2 nearly zoo times.

bottom of Pasteur’s statement, that certain

brown-walled cells which are found on succulent fruits are the resting-states of

species of Saccharomyces which excite fermentation. It will be well therefore to

repeat here my former description of the plant which has been confirmed by Löw

(see Fig. 123).

Small ellipsoid cells sprout in large quantities in a saccharine solution or in water
from the colourless branched and septate mycelial hyphae of Dematium, some from
the extremities of short branches, some from their sides. They are abscised and
multiply in exactly the same way as the cells of Saccharomyces. Finally, when the
available food is exhausted, the mycelial hyphae divide by transverse walls into cells
which are as long as broad and then swell into a roundish shape ; their membranes
also become thick and two-layered and of a brown colour, and they secrete small drops
of oil in their interior. The free sprout-cells show the same changes under similar
conditions. When they are again placed in a suitable fluid, each brown cell goes
through a period of rest, and then puts out a germ-tube, which proceeds to abscise
fresh cells either at once or after it has developed into a branched hypha. The
sprout-cells of Dematium attain a considerable size and then become of an elongate

&
&
ce

272 DIVISION II-—COURSE OF DEVELOPMENT OF FUNGI.

cylindrical form, and not unfrequently grow into long “septate hyphae. But many
remain of a smaller size, and these together with their secondary sprouts may easily
be mistaken for Saccharomyces.

The other Fungi enumerated above, with the exception of those which are classed
with Saccharomyces, agree with Dematium under favourable conditions in forming
hyphae; for this fact the names of the observers given above are a sufficient
guarantee.

Secondly, among these sprouting Fungi some species have the power of exciting
alcoholic fermentation, others have not. Both kinds are found even in the genus
Saccharomyces ; S. Mycoderma, the flowers of wine, usually belongs to the second
category, the other ascogenous forms to the first ; of the species, which as far as we know
at present do not form asci, S. apiculatus belongs to the first category, S. glutinis, Cohn*
to the second. .Mucor racemosus is an inciter of fermentation when it developes the
sprouting form. E. Hansen? has recently studied two forms, not yet certainly
determined but resembling Saccharomyces, which are powerful fermenting Fungi and
are developed from the hyphae of a mycelium. Most of the other sprouting forms
mentioned above either excite no alcoholic fermentation or only a trace of it. The
former is the case, for instance, with the sprout-cells of Exoascus Pruni, Dematium,
and Fumago, which are very like those of Saccharomyces, and may be affirmed of
most of the other species in the absence of any statements to the contrary. Sadebeck
found signs of the formation of alcohol in the case of Exoascus alnitorquus.

Thirdly and lastly, alcoholic fermentation is not confined to the sprouting form ;
some species can excite it in the hyphal form also. Mucor racemosus is an instance
of this and Eurotium Aspergillus glaucus also, according to Pasteur %.

If we consider that these various matters were not originally kept separate from one
another, and that, as has been already said, really distinct species were often enough
mixed up with one another, we see an explanation of the protracted disputes mentioned
above, and we need not enter upon any long account or critical examination of
them in this place ; these will be found in the publications cited on page 127, and in
the works of Reess, E. Hansen, and Pasteur on Saccharomyces and yeast mentioned
below, as also in the first edition of the present book. We shall arrive even in the
present day at very different conclusions, according as we understand the word Yeast-
fungus to mean the sprouting form, or the exciting cause of fermentation, or Saccharo-
myces in particular; but then our disputes become only a contest about words. From
this point of view we must criticise the confusion which Brefeld has recently tried to
introduce into the history of the ‘ Yeast-fungi.’ He has done good service by proving
that the sprout-form is more general than was supposed, but then he proceeds to mix
all the sprout-forms together under the name of yeast; moreover since some sprout-
forms, those for example of Exoascus, may according to their position in the course of
development be conveniently termed the spores or gonidia of Fungi which form
hyphae, he transfers this designation under the name of ‘conidia-fructification ’ to
all his Yeast-fungi, that is to his sprout-forms. In doing this he forgets or misunder-
stands the facts at present known about Saccharomyces of which an account has
been given in the preceding pages, and to which we must adhere so long as no new
ones are put in their place.

Literature.

1. Papulaspora and Helicosporangium.
E1paM in Cohn’s Beitr. III, p. 411, t. 13.

! This name may be given to a rose-coloured form growing on boiled potatoes, which answers
to Cohn’s description (Beitr. I, p. 187).
? Bot. Centralblatt, 1884. 3 Etudes sur la biére, p. 100.

CHAPTER V.—COMPARATIVE REVIEW.—DOUBTFUL ASCOMYCETES. 273

2. Laboulbenieae.

J. PEYRITSCH, Ueber d. Laboulbeniaceen, &c. (Sitzungsber. d. Wiener Acad. 64,
Abth. 1, 1871 ; 68, Abth. 1, 1873 ; and 72, Abth. 3, 1875), in which a full account
is given of the literature of the subject.

Ch. Robin (Végét. parasites) was the first to distinguish the Laboulbenieae, and
Karsten first gave a more detailed description of Stigmatomyces in his
Chemismus d. Pflanzenzelle, 1869.

3. Exoascus.

M. J. BERKELEY, Introd. to Cryptog. Bot. p. 284.

L. FUCKEL, Enumeratio fungorum Nassoviae, Wiesbaden, 1861, p. 29.

DE Bary, Exoascus Pruni (Beitr. I, p. 33).

L. R. TULASNE, Super Friesiano Taphrinarum genere (Ann. d. sc. nat. ser. 5, V,
p- 122).

REEsS, Bot. Unters. über d. Alcoholgährungspilze, Leipzig, 1870, p. 77 ;—Id. (Kutso-
mitopulos), Zur Kenntn. d. Exoascus d. Kirschbäume (Sitzungsber. d. Phys.
Med. Ges. zu Erlangen, 11, Dec. 1862), with some notices of the literature.

P. MAGNUs in Hedwigia, 1874, p. 135, and 1875, p. 97, with a figure.

M. SOROKIN, Quelques mots sur l’Ascomyces polysporus (Ann. d. sc. nat. ser. 6,
IV, 1876).

E. RaTHay, Ueber d. Hexenbesen d. Kirschbäume (Sitzungsber. d. Wiener Acad.
83, Abth. 1, Marz, 1881).

SADEBECK in Verhandl. d. Ges. f. Bot. zu Hamburg, I, 1881;—Id. in Tageblatt d.
55 Vers. d. Naturf. zu Eisenach ; see also Bot. Centralblatt, 1882, XII, p. 179;
—Id. in Winter, Pilze von Deutschland, &c., I, Abth. 2, p. 3.

4. Saccharomyces, ‘ Yeast-fungi’ and their allies.

L. PASTEUR, Mémoire sur Ja fermentation alcoholique (Ann. Chim. et Phys. LVIII,
1860) ;—Id., Etudes sur la biére, Paris, 1876.

M. REess, Bot. Unters. ii. d. Alkoholgährungspilze, Leipzig, 1870, with an enumera-
tion of the older literature ;—Id., Ueber den Soorpilz (Sitzungsber. d. Phys. Med.
Ges. z. Erlangen, 9 Juli, 1877, und 14 Jan. 1878).

ENGEL, Les ferments alcooliques, 1872.

L. CIENKOWSKI, Die Pilze d. Kahmhaut (Mélanges Biol. Acad. St. Pétersbourg, VIII,
p- 566).

O. BREFELD, Mucor racemosus u. Hefe (Flora, 1873) ;—Id., Ueber Gährung in Thiel’s
Landw. Jahrb., 1875, 1876 ;—Id., Bot. Unters. ü. Hefepilze, Leipzig, 1883.

Emi C. HANSEN, Oidium lactis, Saccharomyces, colorés en rouge, &c. (Meddelelser
fra Carlsberg Laboratoriet, I, p. 235, Résumé, p. 75) ;—Id., Unters. ii. d. Phys. u.
Morph. d. Alkoholfermente in Meddelelser fra Carlsberg Laboratoriet, p. 293 or
159 (Saccharomyces apiculatus) ;—Id., Unters. ii. d. Organismen welche sich z.
verschiedenen Jahreszeiten in d. Luft finden, &c. (Meddelelser fra Carlsberg
Laboratoriet, p. 381 or 198) ;—Id., Unters. ii. d. Phys. u. Morph. d. Alkoholgähr-
ungspilze (Meddelelser fra Carlsberg Laboratoriet, II, p. 30 or 13) ;—Id., Bemer-
kungen ii. Hefepilze (Allg. Zeitschr. f. Bierbrauerei u. Malzfabrication, 1883, p.
871). See also Bot. Centralblatt, XVII, Nr. 6, 1884.

E. Löw, Ueber Dematium pullulans in Pringsheim’s Jahrb. VI.

Other treatises are cited by the above authorities, especially by Hansen; see also
those mentioned above in the notes to the text.

[4] T

274 DIVISION II,—COURSE OF DEVELOPMENT OF FUNGI.

UREDINEAE.

Section LXXIX. The Uredineae, as far as we are acquainted with them, are
all parasites on living Phanerogams and Ferns. Many species are able to complete
their development on one host, as will be described more at length in section CX;
others are obliged to migrate from one host to another in order to arrive at certain
stages of their development.

The mycelium consists of delicate copiously branched septate hyphae, and the
cells thus formed, especially when they are young, contain a large quantity of orange-
coloured oil-drops. The mycelium spreads chiefly in the intercellular spaces of the
parenchyma of the host, but often sends into the interior of the cells short branchlets
which themselves have usually short branches, and are then considered to be haustoria
(see section V). In Hemileia only haustoria were found by Ward which have the
form of unbranched vesicles on slender stalks, not unlike those of Cystopus. We are
at present able to divide the Uredineae into two groups according to the course
of their development, aecidia-forming Uredineae and the tremelloid Uredineae.

The development in the former group, which will be first considered separately
from the other, agrees so nearly with that of the typical Ascomycetes, that certain
stages in each group may be regarded as homologous with one another, though
it must be allowed that the proof of the homologies is not quite perfect.

The sporocarps are termed aeczdia, and are developed in the subepidermal
parenchyma of the host; the mode of development, except in one case which will be
noticed in the sequel, is as follows (see Fig. 124 7).

The first beginnings, primordia, are found in the intercellular spaces of the
parenchyma of the host and are composed of a dense weft of felted mycelial hyphae
with air-containing interstices, at first scarcely larger than a cell of the parenchyma,
but gradually increasing in size and displacing the surrounding elements of the
tissue. The separate cells of the originally narrow cylindrical hyphae of the pri-
mordium increase in circumference, the change proceeding from the centre to the
periphery of the primordium, and it gradually acquires the appearance of a body of
pseudo-parenchyma with round or ellipsoid thin-walled pellucid cells, and narrow
interstices containing air. This body, which corresponds in all important points to the
one to which I formerly gave the name of derithecium, continues to be enclosed in a
weft of ordinary mycelial filaments, which are directly continuous with the elements
composing its exterior surface. It lies with its apex just beneath the epidermis
of its host, while its base reaches some way down into the parenchyma (Fig. 124 A).
In form it is spherical or flattened vertically. The Aymenium now makes its
appearance at the base of the aecidium, on the flat surface which abuts on the
surrounding mycelium ; it is composed sometimes of an irregularly shaped, but much
more usually of a circular and continuous layer of short cylindrically club-shaped
basidia directed vertically towards the apex ; each basidium abjoints a single long row
of spores in basipetal succession one after another (Figs. 124 a, 125) with temporary
intermediate cells (page 71). The surface-diameter of this layer and the number
of its basidia are at first comparatively small, and some time is required before
the ultimate breadth of the mature hymenium is reached; whether the new basidia
are inserted between those which are first formed, or grow up outside them, has not

CHAPTER V.—COMPARATIVE REVIEW.—UREDINEAE. 275

been ascertained. The spores are between round and polyhedric, more rarely
ellipsoid and filled with a dense protoplasm, which is sometimes colourless, but is
more commonly coloured by a reddish yellow oil; the walls of the spores are
colourless or of a brownish colour, and often show the prismatic structure described
on page Too.

The hymenium and the rows of spores which proceed from it are enclosed
in a membranous envelope composed of a single layer of cells (the peridium, pseudo-

Fic. 124 Pucetntia gramints. A portion of a thin transverse section of a leafof FIG. 125. CArysomyxa Rho-
Berberis vulgaris with a young aecidium beneath the epidermis 7, J section through a dodendri. Basidium from an aeci-
spot in a Rerberzs leaf containing aecidia. At A is seen the normal structure of the leaf, dium bearing a chain of spores.
the part #—y’, which contains the Fungus, monstrously thickened ; —o upper surface of Magn. 600 times. For the explan-
the leaf. sf spermogonia. @ aecidia opened by a section through the middle, » their ation of the figure see page 71.

peridium. The specimen marked with 2 only without an @ shows the peridium exposed
by the section in a surface-view. // group of ripe teleutospores bursting through the
epidermis e from the tissue 4 of a leaf of 7rttzcum repens; t tcleutospores. /// teleuto-
spores fand uredospores vr. See above, p. 62. From Sachs’ Lehrbuch. / slightly magni-
fied, // magn. 190, /// 390 times.

peridium or paraphyses-envelope); the cells of the envelope are in rows like the

spores, and it grows farz passu with the chains of spores and by the constant

addition of new elements from the base. ‘This growth is effected by a compact

annular row of cells, like basidia, which occupy the margin of the hymenium,

and it advances therefore exactly in the same way as that of the spore-chains, but

without forming intermediate cells. The cells of the envelope are united laterally to
172

276 DIVISION II,—COURSE OF DEVELOPMENT OF FUNGI.

one another without interstices, the uppermost inclining towards one another and
closing over the apex of the spore-chains ; and as this is done from the first, before
the hymenial layer has reached its definitive breadth, the envelope is formed at least
at the same time as the first basidia, and perhaps before them. All cells of the
envelope are polyhedric in form, and are distinguished from the spores by their
larger size, by their thicker wall which often shows a very delicate prismatic structure,
and by their slightly granular or quite pellucid contents, ultimately often containing
air. The spore-layer consisting of the spore-chains with the envelope increases in
circumference by the constant introduction of new elements from the base and their
subsequent enlargement, and encroaches on the surrounding pseudo-parenchyma.
Its increase in breadth squeezes the adjacent cells together till they can often be
no longer recognised. By its growth in length the summit of the perithecium
is first pierced, the epidermis of the host is ruptured, and the spore-layer is
raised with the summit of the perithecium above the epidermis and grows, if pro-
tected from injury, by constant additions from below into a tube filled with spores
and upwards of ı mm. in length. After it has burst through the epidermis, the
cells of the envelope separate from one another
at the apex, and the envelope itself opens out
into the shape of a cup (Fig. 124 J a), or in
4 some species (Gymnosporangium Sabinae) is
9 split longitudinally into narrow lobes; the upper-
most ripe spores fall out, and this disintegration
of the envelope and the spore-chains advances
in the direction of the base, more rapidly in
exposed specimens and when the moisture of the
surrounding atmosphere varies than in cultivated
FIG. 126. Puccinta graminis. a median section and carefully protected plants.

through a spermogonium in the leaf of Berberis vulga-

ris, bursting out from the epidermis e—e. 6 sterig- . G ®
mata from a similar spermogonium with young sper- The exceptional case mentioned above 1s
Malia: @ Magn. 200? about 350 Ames, exemplified in the aecidia of the genus Phrag-

midium, which are distinguished from all others
in the mature state by having no compact tubular envelope. In place of an envelope
a circle of club-shaped unicellular hairs, paraphyses, occupies the margin of the
hymenia, which often spread out into broad cushion-like layers; their earlier de-
velopment has not been investigated.

Except in a very few cases the aecidia are always accompanied by sdermogonia,
which are in all points very like the more simple organs of the same name described
above in Collema and other Lichen-fungi (Figs. 124 I sp, 126). In most species they
are small roundish to flask-shaped receptacles, looking to the naked eye like dots
sunk in the subepidermal tissue, and have a thin smooth wall formed of several
layers of closely woven hyphae which at length opens in the epidermis. The wall
encloses a single cavity, and closely packed séerigmaéa springing from the whole of
the inner surface of the cavity converge towards its centre leaving a narrow space free,
which is afterwards densely filled with spermatia. A few rows of narrowly subulate
pointed Zaraphyses or periphyses grow from the mouth of the receptacle instead of
the sterigmata, and pierce through the epidermis and issue to the open air, forming
a slightly divergent tuft, in the middle of which is the very narrow canal of the mouth,

CHAPTER V.—COMPARATIVE REVIEW.—UREDINEAE 77

The sterigmata are shortly subulate unicellular hyphal branches. They abjoint at
their apex in basipetal order a succession of narrowly ellipsoidal spermatia wrapped
in a mucilage and forming a single row. The morphological characters of these
bodies which have been ascertained are the same as those described above in Collema,
&c. They collect in the cavity of the spermogonium and are discharged through its
mouth, when the investing mucilage swells by accession of moisture. Like the
' spermatia of the Ascomycetes, they have never been known to germinate.

Small deviations from the above arrangements have been observed; in some
species the spermogonia are formed on the outer surface of the epidermis, only covered
by the cuticle, through which they ultimately force their orifice, as in Puccinia
Anemones, Peridermium elatinum and Phragmidium, and hence they have a flatter
basal surface ; in others the paraphyses at the orifice do not protrude beyond the epi-
dermis, as in Chrysomyxa, or are entirely wanting, as in Phragmidium. The sper-
mogonia dry up when they have discharged their spermatia, and their colour, which
is at first yellow or reddish yellow, changes to brown.

The spermogonia, where they occur, are always the precursors of the aecidia
which belong to them, that is, they are always present in a fully developed state when
the first beginnings of the aecidia make their appearance in their neighbourhood.
All these facts point to a physiological relation of the two organs to one another
similar to that which exists between the spermogonia and sporocarps of the
Collemeae. But a more certain proof of this relation is still wanting; the organs in
question must therefore for the present be classed with those in which the
physiological import is doubtful.

It was conjectured that in the Uredineae as in the Ascomycetes the spermatia were
sexual fertilising organs, as soon as it was understood that the spermogonia are parts
of the species which form aecidia, and do not represent, as their discoverer Unger
supposed, distinct species of Fungi. The arguments for that conjecture were and are
the same as those which have been discussed in connection with the Ascomycetes ;
this is sufficiently apparent from the foregoing statements, and they need not be
repeated. Further reflection suggested that only the sporocarps known as aecidia
and no other bodies could be the products of the presumed fertilisation, because it
is the aecidia which are almost always preceded by the formation of spermogonia and
spermatia. But there have always been minor objections to this view. In some cases
spermogonia occur as the companions or precursors, not of the aecidia, but of gonidio-
phores, the layers of the uredospores and teuleutospores which will be described
presently. This is the case in Puccinia fusca (Anemones), P. suaveolens and some
others, but it occurs only in some particular species and the objections founded on it
are easily met by the suggestion that in these species we have to do with the male
gonidia-forming plants of dioecious species, while the female plants occur perhaps
elsewhere or for some reason are not known. Again, I have given’ a description of
a case in which Endophyllum sempervivi, which usually forms spermogonia in the
ordinary way, produced aecidia with normally developed and fertile spores on plants
cultivated in perfect isolation, without any spermogonia or spermatia being found
upon them. Schröter found the aecidia on some cultivated specimens of Puccinia
Alliorum always unaccompanied by spermogonia; in Puccinia Galiorum on Galium
Aparine, and in Uromyces Viciae Fabae on Ervum hirsutum, spermogonia were
constant in the spring, but in the later part of the year there was a copious formation

1 First Edition, p. 169.

278 DIVISION II. —COURSE OF DEVELOPMENT OF FUNGI.

of aecidia, but no spermogonia. But these may be exceptional cases connected
with parthenogenetic development, and would be no valid objection to the presence
of sexuality as a rule, if the latter is supported by other and sufficient reasons. But
these are at present wanting. We know of nothing in the Uredineae, which, like
Woronin’s hypha in Xylaria, can be regarded with any probability aseven arudimentary
archicarp, much less therefore as a distinct female sexual organ or even carpogonium.
Yet it cannot be maintained with absolute certainty that there is no such organ, for we
are still unacquainted with the first beginnings of the hymenium with its envelope ; there
is a gap in the observations, and technical difficulties which are not yet overcome
stand in the way of the completion of our knowledge. In young groups of aecidia a
phenomenon is observed not unfrequently and without great difficulty, which seems to
be in favour of the supposition that there is an archicarp duly equipped for conception ;
short obtuse hyphal branches project from some of the stomata like the tips of the
trichogyne in Polystigma (see on page 215) and may be traced here and there to a
young perithecium. But the chief point, the continuity of such a possible trichogyne
with the supposed archicarp on the one side and on the other its distinct relation to the
spermatia, has not yet been shown; there is nothing in the phenomena observed which
compels us to speak of trichogynes and not simply of branches of the mycelium which
may as well grow outwards from a stoma as in an inward direction into an inter-
cellular space.

In presence of this uncertainty we cannot at present deal with the recently published
statements of Rathay, that the spermogonia of the Uredineae allure insects to visit
them by their fragrance which has long been known, by the saccharine contents
of the mucilage which surrounds the spermatia, and by their colour which is often
supplemented by the bright red or yellow tints of the part of the host where they occur,
and thus make them involuntary agents in the dispersion of the spermatia.

The spores, as they may be shortly termed, which are produced in the
aecidium are mature and capable of germination from the moment that they are set
free from the hymenium, and retain their vitality for some weeks under favourable
circumstances. In a moist environment they put out—usually from pores previously
formed in their wall (see page 100)—thin-walled germ-tubes which receive the proto-
plasm of the spore-cavity together with the oily colouring matter; each spore forms
as a rule only one tube. The next stages in the growth of the tubes and in connection
with them the general course of development in the species exhibit in the better
known cases two chief sets of phenomena.

In ine first case observed only in the genus Endophyllum the germ-tube, when it
has become about ten times longer than the diameter of the spore, ceases to lengthen
and assumes the characters of a promycelium (see on page 111), It then
divides at once by transverse walls, and each of the cells thus formed, generally four
or five in number, with the exception usually of the lowest, sends out a short
subulate lateral sterigma, and on its apex abjoints a thin-walled curved ovoid spore
(Fig. 127). This is called a sporddium to distinguish it from other spores. Regarded
from another connection it belongs to the category of gonidia, if the view of the nature
of an aecidium with which we set out is the true one. The promycelium dies away
when the sporidium has been abscised. The sporidia germinate under favourable
conditions immediately after abscision, sending out a germ-tube which penetrates
through an epidermal cell into the parenchyma of the proper host, and there
developes into a mycelium which ultimately produces new spermogonia and
aecidia. This completes the life history of the plant.

CHAPTER V.—COMPARATIVE REVIEW.—UREDINEAE. 279

Section LXXX. In she second and much most common case the germ-tube
of the aecidiospores does not become a promycelium, but forces its way by
acropetal growth through a stoma into the interior of the host, and there developes
directly into a mycelium. The mycelium ultimately forms gonid:a on distinct
hymenia and always by acrogenous abjunction ; and the gonidia, which can germinate
either directly or after a period of rest, develope a promycelium with sporidia like
that of Endophyllum. The sporidia are usually obliquely ovoid like’ those of
Endophyllum, but in some species are round. The germ-tube of the sporidia when
it has penetrated into the host gives rise to a new mycelium producing spermogonia
and aecidia. These gonidia which form promycelia have been named /eeutospores
(Fig. 124 II, III, Fig. 128 A, and Fig. 129).

The species which produce aecidiospores and teleutospores are again dis-
tinguished into two subordinate groups according to the stages in the course of the
development. In some the stages of the development in the order of their
appearance are mycelium, aecidium, teleutospore, promycelium, sporidium, and there
are no others. This is the case in Gymnosporangium, Puccinia section Hemi-
puccinia, as for instance in P. Falcariae.

In other species the mycelium formed from the
aecidiospore produces other gonidia besides the teleuto-
spores, which are called uredospores (Tulasne’s stylospores).
These too arise by acrogenous abjunction (Fig. 124 //J, ur),
and as regards the time of their development they may be
said to be always the precursors of the associated teleuto-
spores. They are formed according to the species either
in the same hymenia as the teleutospores, or apart from
them in special ones which are simply styled uredo or
uredo-layer. Being short-lived they are able to germinate
immediately after abscision, and put out a germ-tube
(Fig. 128 D) which penetrates through a stoma into the gic. 12. Endophyllum Sempervivi,
tissue of the host like the aecidiospore, and developes Kyle and a ondnem almost fully

mycelium and a sporidium almost fully
5 er < a. h i ‘
directly into a mycelium. The mycelium forms only new Magn scum ost sierigma

Magn. 200 times.
uredospores and teleutospores, and since the process of
germination, the development of the mycelium, and the formation of the uredo on
it are very rapidly performed, the sowing of an uredospore is followed in from
six to ten days under favourable circumstances by the ripening of the uredo of
the next generation; thus they are especially effective organs for the dissemination
of the species which produce them abundantly,

To complete our account it must be added that the mycelium which forms
aecidia may in exceptional cases subsequently produce gonidia, that is teleutospores
with or without uredospores. Sometimes individuals of a species, as in Uromyces
appendiculatus, sometimes single species are distinguished from the majority by the
regular occurrence of this phenomenon, as Uromyces Behenis, U. Scrophulariae,
U. Cestri, and Puccinia Berberidis. It is moreover not unusual for the germ-tubes of
sporidia, when they cannot penetrate at once into the host, first to abscise a secondary
sporidium at their apex, which has the characters of the original sporidium.

It has been already said that both kinds of gonidia are produced on hymenia on

280 DIVISION IL.—-COURSE OF DEVELOPMENT OF FUNGI.

the outer surface of somewhat cushion-shaped bodies, which are formed by
the interweaving of mycelial hyphae immediately beneath the epidermis of the
host, more rarely at a greater depth, and burst through it when they form spores.
Both are formed acrogenously on crowded sporiferous cells (sterigmata, basidia),
which cover the outer surface of the hymenium, either alone or in certain species
mixed with or surrounded by paraphyses of peculiar structure; in a few cases, as the
uredo of Melampsora populina, and of Cronartium, they are enclosed in a one-layered

FIG. 128. Puccınia graminis. A a pair of teleutospores ¢ germinating with pro- FIG. 129. Pugeinia Rubiyo vera.
mycelium and sporidia sf. 3 a promycelium with sporidia sf torn from the spore. Pair of teleutospores, the lower
C epidermis of the under surface of the leaf of Berderis vulgaris with a germinating not having germinated, the upper
sporidium sf, the germ-tube from which has penetrated at z into an epidermal cell. inating; 2 p ycelium, s
D uredospore putting out a germ-tube fourteen hours after being placed on water. sporidium, Magn. 390 times.

Four equatorial germ-pores are seen on the empty spore-membrane, C, D magn. 390
times, 4, B somewhat more highly magnified.

envelope like that of the aecidia, the development of which has yet to be more closely
examined.

The uredospores are formed in some species in successive rows and with
intervening cells like the aecidiospores, in others singly on slender stalk-like sterigmata,
from which they always separate by abscision as they ripen with a view to their
dispersion. Their form and structure agree essentially with those of the aecidiospores,
Hemileia being the only exception. The teleutospores of most species are formed

CHAPTER V.—-COMPARATIVE REVIEW.—-UREDINEAE. 281

in the same way as the uredospores, only there are no intervening cells (Figs. 129,
130); but in Triphragmium three spores are formed on the same plane by simul-
taneous (?) division in the solitary acrogenetic mother-cell, and in Melampsora the
mother-cell is divided by longitudinal walls into several (four) spores placed side by
side. The teleutospores are generally distinguished from the uredospores by two
peculiarities as well as by their mode of germination. In the first place they do not
separate from the sterigma, but in most species remain with it at their place of origin
until they germinate; more rarely, as in some species of Uromyces and Puccinia
(Uromyces Phaseolorum, Puccinia fusca, and some others), they become disengaged,
though not from the sterigma, since they carry with them a portion of the sterigma, which
is severed from the hymenium by a transverse rupture. Secondly, all teleutospores are
filled when they are mature with a finely granular protoplasm which is either
colourless or coloured by a very finely comminuted reddish yellow fatty matter
surrounding a comparatively small spherical cavity, the cavity itself being filled
with a weakly refringent substance. Whether this is a nucleus or a space containing
a nucleus or something of another kind is not yet certainly ascertained. In other
respects, such as their special mode of formation, their connection with each other
and with the hymenium, their configuration and the structure of their walls, there is
considerable variety among the teleutospores, and the distribution of the Uredineae
into genera has been founded chiefly on these differences. The mode of germination
is very similar in them all; Coleosporium only differs from other genera in the
circumstance that the teleutospores, which are placed one above the other in rows,
generally four together, each put out one sterigma only in germination, and the
sterigma abscises a sporidium, so that a row of germinating spores resembles in
outward appearance the promycelium of other genera.

It appears from the foregoing review that the simplest known course of development
among the Uredineae which form aecidia is found in the Endophylleae. But even here
between the aecidiospore and the next generation which forms aecidia there is always
an intervening alternating generation which forms gonidia, the promycelium with its
sporidia, though it is only a transitory state. In the two known species, Endophyllum
Sempervivi and E. Euphorbiae, a year elapses between the formation of two successive
aecidium-generations, and this time is employed in the complete development of the
mycelium in the tissue of the perennial host. There may possibly be species in which
the course of development is still further simplified by the absence of sporidia, the
germ-tube from the aecidiospore developing directly into the mycelium with aecidia ;
but these the simplest conceivable species are not known. The simple tubes which
may develope from the spores of Endophyllum when they are placed under water
do not become promycelia, and are, as far at least as we at present know, incapable
of further development.

The intercalation of teleutogonidia and uredogonidia in the course of development in
the other species, either as necessary or at least as regular members of it, makes it more
complicated, and there are various degrees of complication in different species according
to the greater or less abundance or the entire absence of the uredo. Besides
these purely morphological gradations there are biological differences also, which give
an extraordinary variety to the actual living forms in the plants by frequent change of
combinations from species to species. The chief difference here is that the teuleuto-
spores of some species germinate as soon as they are ripe, those of others are obliged to
pass through a period of rest; the former mature in the period of vegetation, the
latter mature at the end of one period and germinate at the beginning of the next.

282 DIVISION 1I.—COURSE OF DEVELOPMENT OF FUNGI.

The first species that were more thoroughly studied belong to the latter category. It
was natural therefore to begin the account of their life-history with the formation
of sporidia, and then the teleutospores form its close; this is the origin of their
name.

Since the special forms of these teleutospores serve to characterise form-genera
which are still preserved in an altered sense, they still bear special names derived
from these genera, as Puccinia spores, Triphragmium spores, Phragmidium spores, &c.
Tulasne called them simply spores, to distinguish them from the rest. The Zerms
uredo and aecidium at present in use were originally the names of form-genera,
and were retained, but with an altered meaning. The fact that almost all the aecidia
and uredines, unlike the teleutospores, were included in a single form-genus points
to a very great similarity in the forms of the same name, and there is this similarity
in fact between most of the aecidia. More minute investigation has already discovered
greater variety among the uredines, and especially two chief types in the abjunction of
the spores, namely, solitary abjunction on filiform sterigmata, as in Puccinia, Uro-
myces, and other genera, and successive serial abjunction, as in Coleosporium and
Chrysomyxa. A more considerable departure from all others is found in one genus only,
Hemileia.

There is no need to enter here into the details of the combinations which arise from
the points of view indicated above and of their application to the determination and
grouping of species and genera, since they can be seen quite well in Fungus-floras ; the
reader is especially referred to Winter’s Pilzflora.

Section LXXXI. Beside the many species of aecidia-forming Uredineae which
are now known to us in the whole course of their development, there are a number
of forms which resemble them so closely in certain portions of it, that they are
regarded without hesitation as their homologues, though their complete life-history
has not yet been ascertained. The further development of the stage with which the
investigation begins has been followed for a certain distance, but without returning
again to the starting-point. It is therefore also still uncertain what kind of organs
actually belong to the course of development in each species. Examples of this are
found in abundance in the Floras, and include every kind of known organs. In
Peridermium elatinum for example, Phelonites strobilina, Aecidium Sedi, and many
others we know only the aecidia, in Phelonites strobilina not even the germination of
the spores; this is known in the two other species and agrees perfectly with that of
other aecidia which do not form a promycelium, but it is not known how and where
the further development of the germ-tubes takes place. The teleutospores only are
at present known in some Puccinieae, in Uromyces and Triphragmium echinatum, &c.,
and their germination has been partly observed, but we have not yet learnt what
proceeds. from the sporidia. A Fungus, for instance, in which the uredo only is
known, is described as Uredo Symphyti, the name Uredo being still inconsistently
but intelligibly employed to denote a form-genus; in the case of some forms included
under the form-genus Caeoma (Tulasne), as C. Mercurialis, C. Euonymi, and some
others, it is doubtful whether they are to be considered as uredines or as naked
aecidia like those of Phragmidium. Species like Melampsora Salicina and M.
populina, Coleosporium Campanularum, Hemileia vastatrix, &c. form uredospores
and teleutospores, and are reproduced with these spores in unlimited numbers from
the germ-tubes of the uredospores. The teleutospores form promycelia with
sporidia, but no one has been able to find out what becomes of the sporidia.

Cases like the one last mentioned on the one hand, and on the other the

CHAPTER V.—COMPARATIVE REVIEW.—UREDINEAE. 283

occurrence of aecidia with fertile spores outside a known typical cycle of development,
would in themselves be sufficient ground for supposing that we are here, in the main
at least, simply dealing with Uredineae whose course of development is the same as
that described above, but is only imperfectly known to’ us because we have not yet
ascertained the conditions for the further development of the particular organs on
which the investigation turns. Experience, and especially the discovery of the
phenomena of a change of host (section CX), have to a great extent confirmed
this supposition; fresh typical species forming aecidia are being constantly completed
out of the separate stages known to us, and we may therefore say with confidence
that many of the gaps still existing are only gaps in our knowledge and not in the
development of the species. This, it is true, does not exclude the @ przor? possibility
that our scheme does not fit every case. There are perfectly well-known species
coming under it, for instance Puccinia Rubigo vera of our corn-fields, which are
reproduced year after year in frightful quantities by the uredo only. They produce
also millions of teleutospores which germinate but without result, because the |
sporidia seldom meet with the conditions necessary for developing aecidia. Aecidia
certainly are developed if the conditions are favourable; but the instance shows
that the species can multiply abundantly without the interposition of aecidia, and
hence there is nothing to prevent the assumption that there may also be species
in which the aecidia are not only rare but are altogether wanting ; perhaps they once
were there but have been lost, while the other members of the development,
uredospores, teleutospores, and sporidia -have maintained their existence without
changing their former characters. Other species may then have also lost the
teleutospores which had become useless to them and become confined to the uredo
only. These are at least possibilities which may be cautiously weighed and tested
by further investigations. We are led up to them by another path also, which will be
discussed in the next paragraph.

Section LXXXII. There are Uredineae of which it may or must be acknow-
ledged that the cycle of their development, which is known to us throughout, is
different from that of the Uredineae which form aecidia. The species here alluded
to are known as the tremelloid Uredineae, to which the Leptopuccinieae and
Leptochrysomy<xa also belong.

Organs are known in the tremelloid Uredineae which in structure, development,
and germination with formation of sporidia resemble in all essential points the zelewto-
spores of species of Puccinia which form aecidia, and may therefore be called by that
name, being distinguished at most from the teleutospores of most of these species by
having their spore-membranes as a rule softer and more gelatinous. But this is not
always the case ; the aecidia-forming Puccinia Berberidis from Chili, for example, which
unfortunately is only known to us from old specimens in collections, agrees in this respect
with the Leptopuccinieae which have the softest spores. In this species of Puccinia and
in all Leptopuccinieae this character is connected with another peculiarity; the teleuto-
spores, or at least the great majority of them, germinate as soon as they mature and
while they are still crowded together on the comparatively long stalks by which they
are attached to their nutrient substratum. Schröter found that in some species, as
Leptopuccinia Circaeae, L. Veronicae, and L. annularis, teleutospores with thicker
walls were also formed in addition to the others, and that these cannot germinate

284 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI,

without a winter’s rest. The further development of the sporidia abscised from the
promycelium is perfectly known, at least in L. Dianthi, L. Malvacearum, and L.
Circaeae; the germ-tubes from the sporidia penetrate at once into the proper host,
either through the wall of an epidermal cell, as in L. Malvacearum, or through a
stoma, as in L. Dianthi, and develope a mycelium which again produces only teleuto-
spores. Aecidia and uredines have never been observed in these species.

A similar relation to this between the Puccinieae which form aecidia and
Leptopuccinia exists between the Chrysomyxae and Leptochrysomyxa. The former
(Chrysomyxa Ledi and Ch. Rhododendri) form aecidia, teleutospores, and uredines
in the regular succession. The teleutospores (Figs. 130, 131) are cylindrical cells with
soft colourless membranes forming simple or branched pluricellular rows, which stand
densely crowded together parallel to one another and perpendicular to the surface of
the hymenium. They germinate as soon as they are ripe, and where they are formed.

FIG. 130. Chrysomyxa Rhododendr: in a leaf of RA. hirsutum, Vertical section FIG. 131. CArysomyxa Rhodo-
igh a lay e—¢ epidermis of the under surface of the leaf. Adjoining dendri. A single isolated row of
the spores is the tissue of the leaf traversed and distorted by mycelial filaments 7 of Me after letion of
Chrysomyxa; a a row of teleutospores which have not yet germinated; / a similar row germination and shedding of the
in which the uppermost teleutospore has formed a promycelium, and on this sterigmata sporidia,
and sporidia are beginning to be formed in basipetal succession. Most of the other rows

show the first ofthe ion of promycelia on the upp teleuto-
spore. Magn. 140 times,

Leptochrysomyxa (Chrysomyxa Abietis, Unger) forms exactly the same teleutospores
with promycelium and sporidia, which are scarcely distinguishable from those of
the two former species. But the germ-tubes from the sporidia produce mycelia
which only form teleutospores; no aecidia or uredines have ever been observed on
them.

It is evident that the provisions for the life of these species are different from
those of the species first described. This however might be the case while the
morphological conditions remained the same; but here there is the important
difference, that the whole aecidium-generation is passed over and struck out of the
cycle. It may be that it does occur in some Leptopuccinieae which have not been
thoroughly examined as much as in Puccinia Berberidis, and that we merely have
not yet learnt the place and the conditions of its occurrence. We may allow the
possibility of this even in the four last-named species, which have been very often and
very thoroughly examined and in which there is no indication of any formation

CHAPTER V.—COMPARATIVE REVIEW.— UREDINEAE. 285

of aecidia of their own. But this makes no change in the facts observed in the
course of development in the tremelloid Uredineae.

Schröter distinguishes by the name of Micropuccinia a small group, in which
also teleutospores only are known, for instance Puccinia Pruni, P. Aegopodii, and
P. Asari. These forms differ from the Leptopuccinieae in the circumstance that the
teleutospores drop off when they are ripe and only germinate after a long rest.
We have no complete knowledge of their development. It is possible from these
data that it belongs to the tremelloid type, but we must wait for further investigations
to decide this point.

Section LXXXIII. The homologies within the group of the Uredineae are
at once apparent from the foregoing account. The organs of the same name are in
all of them undoubted homologues in the morphological sense. Starting from Endo-
phyllum, the species which are furnished with teleutospores and uredo have a number
of members connected by a variety of gradations in the segment between two
successive sporidia-generations ; but in the tremelloid forms the homology, as far as we
know is interrupted and not restored (see page 125). If, on the contrary, we make the
tremelloid forms the starting-point in the comparison, we then have in the case of the
species which form aecidia an addition, an acquisition of a new and generally
important member of the development, the aecidium with its attendant spermogonia.

It was pointed out at the beginning of these remarks, that the rhythm of the
development in the species which form aecidia is very closely allied to that of the
typical Ascomycetes. There is the most complete agreement between the course of
development in Polystigma (see page 226)and Endophyllum up to the difference between
perithecium and aecidium. At present we know of no intermediate forms between
these two kinds of sporocarps. But the difference between them is sufficient to make
the homology appear questionable. Here is the gap indicated at the outset, for all
other peculiarities in the Uredineae which form aecidia are nothing more than special
cases of the general course of development in the Ascomycetes. But there are no
facts recorded at present which would lead us to infer a nearer connection of the
aecidia on any other side than that of the sporocarp of the Ascomycetes, and
this circumstance, which is in harmony with the agreement in the general rhythm of
the development, to which attention has been repeatedly drawn, turns the scale
in favour of assuming that the two are homologous; anything more than an assump-
tion is of course out of the question. But if this assumption is correct, the Uredineae
which form aecidia belong to the series of the Ascomycetes, as a special subordinate
or collateral group distinguished by special peculiarities of the sporocarp. Further, if
the view taken above of the connection of the Ascomycetes with the Peronosporeae
and Mucorini, and through them with the general system, is correct, the Uredineae
which form sporocarps cannot have been developed from the tremelloid. For
the latter therefore there remains only the assumption that they show a retrograde
development by the loss of the aecidia, being descendants of aecidia-forming
species and apparently homologous with certain segments of their development,
sometimes even so like them that they might be mistaken for them.

Literature.

UNGER, Die Exantheme d. Pflanzen. Wien, 1833.
The rest of the older writers are noticed in the works enumerated below.

286 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

LEVEILLE, Sur la disposition des Urédinées (Ann. d. sc. nat. ser. 3, VIII; and Article
Uredinees in D’Orbigny, Dict. hist. nat.).

TULASNE, Mém. sur les Ustilaginées et les Urédinées, Ann. d. sc. nat. ser. 3, VII,
and especially the Second Mémoire s. ]. Urédinées et les Ustilaginées (Ann. d. sc.
nat. ser. 4, II).

Kühn, Krankheiten d. Culturgewächse, Berlin, 1859.

DE Bary, Rech. sur l. Champignons parasites (Ann. d. sc. nat. ser. 4, XX, page 64) ;—
Id., Unters. ii. d. Brandpilze, Berlin, 1853;—Id., Ueber Caeoma pinitorquum
(Monatsber. d. Berl. Acad. Dec. 1863) ;—Id., Neue Unters. ii. Uredineen
(Monatsber. d. Berl. Acad. Jan. 1865 and Apr. 1866) ;—Id., Ueber d. Krebs u. d.
Hexenbesen d. Weisstanne (Bot. Ztg. 1867) ;—Id., Aecidium abietinum (Bot. Ztg.
1870).

SCHRÖTER, Die Brand- u. Rostpilze Schlesiens (Abh. d. Schles. Ges. f. vaterl. Cultur,
1869) ;—Id., Entwicklungsgesch. einiger Rostpilze in Cohn, Beitr. I, Heft 3, p. 1, and
III, 1, 51;—Id., Ueber einige amerikanische Uredineen (Hedwigia, 1875) ;—Id.,
Aecidium Euphorbiae u. Uromyces Pisi (Hedwigia, 1875).

M. REESS, Die Rostpilze d. deutschen Coniferen, Halle, 1869.

R. WOLFF, Aecidium Pini u. s. Zusammenhang mit Coleosporium Senecionis Lév.
(Festschrift, Riga, 1876).

A. S. OERSTED, Om Sygdome hos Planterne, &c., Kopenhagen, 1863 ;—Id., Ueber
Podisoma resp. Roestelia (Bull. de Acad. Roy. d. sc. de Copenhague, 1866, 1867,
and k. Danske Vidensk. Selskab. Skrifter. ser. 5, VII, 1863).

WORONIN, Puccinia Helianthi (in Russian), St. Petersb. 1871.

R. HARTIG, Wichtige Krankheiten d. Waldbäume, Berlin, 1874.—Id., Lehrbuch d.
Baumkrankheiten, Berl. 1882, p. 49.

W. G. FARLOW, The Gymnosporangia or Cedar-apples of the United States (Memoirs
ofthe Boston Soc. of Nat. Hist. Boston, 1880).

E. RATHAY, Unters. ii. d. Spermogonien d. Rostpilze (Denkschr. d. Wien. Acad. 46,
Wien, 1832).

H. MARSHALL WARD, Researches on the life-history of Hemileia vastatrix (Linn. Soc.
Journal (Botany), XIX) ;—Id., On the morphology of Hemileia vastatrix Berk.
(Quarterly Journ. of Micr. Sc. New Series, XXI).

G. WINTER, Die Pilze Deutschlands, I.

BASIDIOMYCETES.

Section LXXXIV. This group is composed of two large sub-groups, the
Hymenomycetes and the Gastromycetes, and derives its name from the dasıdia
which are proper to all members of the group and abjoint spores acrogenously. These
organs, which were described above on pages 63, 64, are closely crowded together and
usually stand parallel to one another, forming Aymenia on or in the compound
sporophore; they are not unfrequently accompanied by sterile hyphal branches,
which here as elsewhere may be included in Montagne’s term: paraphyses (see page
53). The basidia appear almost always, it may be said indeed uniformly, as the

1 Esquisse organographique, &c. des Champignons.

CHAPTER V.—COMPARATIVE REVIEW.---HFYMENOMYCETES. 287

club-shaped bodies described above producing two or four, seldom a larger number
of spores. No great deviations from the ordinary rule occur except in the Tre-
mellineae and a few exceptional genera, as Tulostoma (section XC) and Kneiffia’,
in which latter the basidia are said to produce only one spore. The ripe spore is
always abjointed as a single cell, except in a few Tremellineae and the doubtful case
of Agaricus rutilus?, and exhibits every gradation in form from spherical to narrowly
fusiform.

Hymenomycetes and Gastromycetes are distinguished from one another by
the structure of their compound sporophores, which we will now proceed to describe.

HyYMENOMYCETES.

Section LXXXV. This division differs from the other in having the hymenium
on the free outer surface of the compound sporophore at or more commonly before
the time of the abjunction of spores. In the simplest cases, such for example as
are presented by Corticium, Dacryomyces, Exobasidium, and some species of
Hypochnus, the compound sporophores do not vary essentially in form and
differentiation from the layers of teleutospores in the Uredineae, such for instance as
the layer shown in Fig. 130, if basidia are substituted for the teleutospores. They
are therefore flat or cushion-shaped bodies which bear the hymenial layer on the free
surface and are attached by the opposite surface to the mycelium or substratum. From
these which are the simplest forms there is a passage into more-highly developed forms
and chiefly in two directions. In the one case the substratum is vertical and the
margin of the compound sporophore which points upwards raises itself from the
substratum and continues to grow nearly at right angles to it; in this way fan-shaped,
mussel-shaped, or horse-shoe-shaped sporophores are formed, bearing the hymenium
on the surface which looks towards the ground and sterile on the opposite side. In
the other case the compound sporophore rises in a vertical, erect position from
the usually, if not always, horizontal substratum and takes the form of the Cap-fungi
and club-shaped Hymenomycetes. The former are obconical bodies or funnel-
shaped or umbrella-like and borne on a stalk; in a few cases the hymenium is on
the surface which is turned away from the substratum, and therefore on the upper,
inner surface in the funnel-shaped form, while the rest of the surface remains sterile,
as in Cyphella, Guepinia, Tul. and Exidia. Generally the opposite is the case, and
the hymenium is localised on the side towards the substratum, on the surface of
the cone and the lower surface of the stalked umbrella, as in Gyrocephalus of Persoon
( = Guepinia helvelloides, Fr.) and most of the Hymenomycetes in the narrow use of
the word. In compound sporophores of the latter kind the portion to which the hy-
menial surface belongs has the special name of cap or pileus, and is placed on a more
or less distinct s/a/k, the sfifes. The term cap or pileus has been extended for
convenience sake from this its original signification to the compound sporophore
generally in which the hymenial surface looks towards the ground, and therefore

1 Fries, Hymenomyc. Europ. p. 628. Berkeley and Broome in Ann. and Mag. of Nat. Hist.
ser. 4, VII, p. 429.
2 Léveillé in Ann. d. sc. nat. ser. 2, VIII, 328.

288 DIVISION 11.—COURSE OF DEVELOPMENT OF FUNGI.

also to those which have the shape of a horse-shoe or fan. The club-shaped Hy-
menomycetes are erect, club-like or cylindrical, unbranched or branched shrub-like
bodies, and have their upper part covered all round with the hymenial surface.
Calocera, Dacrymitra, and the Clavarieae are well-known examples of this subdivision.

A very extensive and almost unbroken series of intermediate forms connects
the chief forms specified above, and is most complete in the group of the Thele-
phoreae.

The Aymenzal surface shows considerable variety of formation, to some extent in-
dependently of the general form of the compound sporophore, and this variety has been
the chief means employed to distinguish the groups and genera of the Hymenomycetes
in the narrower sense. It is smooth or in large irregular folds, and sometimes has
also slight prominences, hair-structures, and similar formations, as in most of the
Tremellineae, Clavarieae, and Thelephoreae. In other groups it is considerably
enlarged by peculiar projections of definite shape ; by teeth or regularly conical sharp-
pointed spikes in Tremellodon and the Hydneae ; by plates, /amel/ae, something like a
knife-blade in shape, which radiate towards the margin of the pileus in the Agaricineae, or
are concentric with the margin in the genus Cyclomyces; lastly, in the Polyporeae
by folds or plates connected together into a reticulation, which are either shallow
(Merulius, Favolus), or grow to such a height that the meshes become comparatively
long narrow tubes (éudul?, pori) united laterally to one another and bearing the
hymenium on their inner surface (Polyporus, Boletus). Between these forms also,
which in their extreme condition are very characteristic, there is no lack of inter-
mediate states. A larger or smaller number of transverse connections between
lamellae or teeth may make a species or even individuals of the same species
occupy a doubtful position on the border-line between Agaricineae and Polyporeae,
or between Hydneae and Polyporeae, and so on. The genera Irpex, Lenzites,
Daedalea, Cantharellus, &c. supply numerous instances of the kind, and should be
studied in descriptive works.

In by far the great majority of cases the construction of these compound sporophores
is by progressive growth of a primordial bundle of hyphae in the direction of the margin
or apex. There may at the same time be intercalated areas where growth continues
longer or recommences, but this point is not certainly ascertained. The instances of
progressive growth of the compound sporophores given in the general description
at page 50 are chiefly taken from the Hymenomycetes, and the reader is referred to
them for further information. Where the hymenial surfaces have projections, it is a
general rule that they retain on the average the same shape, and especially the same
breadth and distance from one another over the whole extent of the surface. The
absolute number of the projections must therefore increase in proportion to the growth
of a fan-shaped or cap-like sporophore at the periphery. This is effected in lamellae
which radiate towards the margin either by bifurcation of the original lamellae, as in
Cantharellus, Daedalea, and some species of Lenzites, or all lamellae when once
formed grow radially marginwards without branching, and new ones are formed
between them from the point where the distance between the old lamellae exceeds a
certain measure; this is what happens in most Agaricineae. Hymenial surfaces
therefore of this kind come to have successively formed lamellae, which, starting from
the margin, either extend as they were first formed to the point of insertion of

CHAPTER V.—COMPARATIVE REVIEW.—HYMENOMFCETES. 289

the pileus, or come to an end on the surface of the pileus at different distances from
the insertion; they may be shortly spoken of as lamellae of different and successive
orders.

Each projection on the hymenium, lamella for example or spike, rises above
the hymenial surface, which in its earliest state is always level, in consequence of the
stronger growth perpendicular to the surface of the hyphae of which it is composed,
as compared with that of the portion of surface between the projections. Each
projection also when once begun grows perpendicularly to the surface and advances
towards the margin. This growth is quickly completed in the many short-lived
forms; it may last for years in less transitory species with periodical alternations of
cessation and recommencement. See page 57.

Attention has been already called at page 56 to the epinasty and hyponasty which
alternate according to the age, especially in rapidly growing forms with a pileus, to

FIG. 132. Agaricus campestris, L. a—c three stages of the development of a pileus in vertical radial longitu-
dinal section slightly magnified, 2 6 mm., 5 16 mm. in length. Successive stages of the development according to
the letters. @ thin section of 4, showing the course of the hyphae, d and di: ically repre-
sented, the veil (annulus).

the consequent primary involution of the margin of the pileus or application of the
hymenial surface to the stipe, and lastly to the expansion of the pileus.

Hymenomycetes with compound sporophores of purely marginal or apical
progressive growth are termed gymnocarpous, because the hymenium lies from
the first on the free surface and is not covered by any special envelope, though
it is protected when young by adjacent hairs and by epinastic curvatures.

Section LXXXVI. Many Agaricineae and some Boleti differ in one respect
from true gymnocarpous forms, since the growth of their stalked pileus or of a
portion of it goes on within a special envelope, which was termed by Persoon
the involucrum, by Fries the velum or veel; the latter name is still generally

[4] u

290 DIVISION II-—COURSE OF DEVELOPMENT OF FUNGI.

adopted. The veil is rent by the upward extension of the pileus, and often, but not
always, in such a manner that a portion of it remains behind on the stipe as an
annular frill (ring or annulus).

The veil appears in two principal forms; first, as a membrane running from
the margin of the pileus to the surface of the stipe, and therefore does not enclose
much more than the hymenial surfaces, but leaves all the other part free; in this case
it may be called a marginal veil, or with Fries velum partiale (Fig. 132). Secondly,
as a sac which encloses the entire sporophore from its base, and is ruptured at the
apex by the unfolding pileus; in this state it is the velum universale or volva (see
below, Fig. 135).

1. As regards the development of the forms which have the marginal veil
only the following special facts have been established by observation. Up to the first
formation of the pileus on the summit of the stipe-primordium the phenomena are the
same in essential points as in the gymnocarpous forms (Fig. 24 a). The young
pileus is entirely delimited from the stipe by
a transverse annular furrow running along
its future hymenial surface. But then the
superficial hyphal layers of the stipe and
of the young pileus send out numerous
branches towards one another from the
edges of the furrow; these unite into a
close weft, the marginal veil, which bridges

es

FS
era

Ira
Ina

a

oe

=.
Fe

N
ae over the furrow and closes it on the outside
Ina, (Fig. 133). The body of the pileus then
N N developes from the inner hyphal layers of

the primordium, those which are nearest the
furrow, and chiefly by uniform growth in
FIG. 133. Agaricus melleus. Half of a thin median longitu- the direction of the margin and by alternate
dinal section through a young pileus before the closing of the a Pr 7 .
veil; # the annular furrow between the pileus and the stipe epinastic and hyponastic growth, as in
bounded above by the of the h i else- 5 . a .
where by the veil which has begun to develope. After R. the species which have no veil. The veil,
Hartig, Wichtige Krankh. d. Waldbäume, t. II. Magnified. r A .
together with the portion of the stipe in-
closed by it, follows the superficial increase
in size of the pileus by intercalary growth, till the hyponastic expansion of the latter
commences.

The veil therefore in these cases is, as Bonorden described it, a continuation of
the outermost row of cells of the stipe, which grows with the stipe for some time by
intercalary growth and passes into the margin of the pileus, and conversely a
continuation of the outermost hyphae of the pileus passing into the surface of the
stipe; it is composed in fact of hyphae of this twofold origin. The structure is
differently formed in each separate case, the difference depending on whether it
begins to be formed in a somewhat later or earlier stage of the development, and in
connection with this whether the hyphae which take part in its formation and run
downwards from the pileus have their origin at a greater or less distance from the
centre of the pileus, while those which run upwards from the stipe reach more or less
of the way to the apex of the pileus; and also on whether the margin and hymenial
projections of the pileus are closely applied to the stipe or are more or less distant

CHAPTER V.—COMPARATIVE REVIEW,—HYMENOMYCETES. 291

from it in consequence of the special localisation of the epinasty. Coprinus lagopus?
on the one hand, and Agaricus melleus? on the other, represent the extreme cases
which have been observed. In the former the hyphae from the periphery of the stipe
reach to the apex of the young pileus from the first commencement of its formation,
and hyphae pass downwards from the whole outer surface of the young pileus, except
the extreme apex, and become interwoven with those from the periphery of the stipe
to form the veil. The margin of the pileus and the edges of the lamellae moreover
lie so close to the stipe up to the time of the hyponastic upward extension, that the
veil has an extremely narrow slit to cross. In Agaricus melleus the formation of the
veil is comparatively late in beginning, the young pileus being already delimited from
the stipe by a deep annular furrow, and the only hyphae which take part in it are the
exterior hyphae of the margin of the pileus and those of the stipe which bound the furrow.
Moreover the margin of the pileus is at some distance from the surface of the stipe,
almost at right angles to it, and the veil therefore spans from the first a comparatively
broad channel, and grows as the pileus increases in size into a collar which in
vigorous specimens may be more than a centimetre in breadth. Most marginal
veils are formed in the same way as that of Agaricus melleus, and Fig. 132 of
A. campestris will serve to illustrate these remarks. Something will be added further
on with regard to its first origin. Fig. 134 shows the phenomena in most species of
Coprinus in the state succeeding the very early ones and in more advanced stages of
development.

The veil continues to grow in all these cases with the general growth of the
pileus until the time of the hyponastic upward expansion of the latter; then it is
ruptured and in more than one way. In most species of Coprinus it separates
smoothly in the direction of the surface of the stipe without leaving any conspicuous
trace of itself behind either on the stipe or on the margin of the pileus. In other
cases, as Hypholoma and Cortinarius, it separates from the stipe and remains
hanging to the margin of the pileus as a membrane which usually tears into irregular
perishable shreds, the veil or velum in the narrower sense of Persoon, the curtain
(cortina) of Fries. Thirdly, the separation takes place at the margin of the pileus,
the veil remains attached to the stipe as a ring running down its surface, the
annulus or annulus inferus, as in Agaricus (Armillaria) melleus above described,
A. (Psalliota) campestris, and many others.

Lastly, in Coprinus ephemerioides* hyphae of the veil grow downwards at
first from the margin of the pileus between those which ascend from the stipe, while
the margin of the pileus and the lamellae lie close to the stipe, as in the other species
of the genus (see Fig. 134). When the elongation of the upper portion of the stipe
and the upward expansion of the pileus begin, the veil is first of all torn away in
consequence of the stretching from its connection with the stipe, and continuing to
be united to the margin of the pileus on the stipe is carried upwards with it. Then
when the upward expansion of the pileus begins, it separates from its margin and
remains behind on the stipe, forming an annular sheath broader above and capable

1 Brefeld, Schimmelpilze, III, t. VII.
2 R. Hartig, Wichtige Krankheiten d. Waldbäume, t. 2.
3 Brefeld, Schimmelpilze, VI.

U2

292 DIVISION II,—COURSE OF DEVELOPMENT OF FUNGI.

of being moved up and down on the stipe in consequence of the first separation, the .
annulus mobilis.

2. In the species of the groups of Amanita and Volvaria which are furnished
with a volva, the development of the pileus is essentially different from that of the
rest of the Hymenomycetes, as far at least as has been ascertained by my older and
Brefeld’s recent examination of the Amaniteae. In this group the compound
sporophore in its earliest state is a small tuber-like body produced on a mycelium
consisting of a weft of hyphae uniformly capable of development. This body grows
in every direction, and not by advance on one side only, to the size of a hazel-nut
or even larger, and stipe, pileus, and lamellae are formed inside it by differentiation
of the tissue, by being moulded as it were out of the originally homogeneous
fundamental mass. The youngest roundish tubers, somewhat more than 1 mm. in
diameter, which Brefeld saw in Amanita muscaria, are close wefts of hyphae,
composed in the larger portion of the tuber of slender cylindrical cells which are

FIG. 134. Coprinus micaceus, Fr. a a young specimen 2 mm. in length in radial longitudinal section; the
annular furrow beneath the future hymenial surface is bridged over on the outside by the veli. 5a specimen 3°5 mm.
in length in radial longitudinal section, ¢ a thin radial longitudinal section igh a

P than 4. dtr section through the middle of the pileus ofc. @ and 4 slightly magnified, a magn.
go times, c less highly ified.

here and there dilated into vesicles. In a small peripheral section, which, from its
position with respect to the substratum, may be called the apex, the hyphal tissue is
exclusively formed of slender delicate filaments, and its elements are evidently in the
act of branching copiously. This apical portion is the primordium of the pileus of
the larger part of the stipe and of the volva which covers the summit of the pileus.
All beside is the young base of the stipe, which is always swollen and tuber-like and
is therefore termed the dudéus. A median longitudinal section through tubers of
about twice the size shows that the tissue of the apical region is differentiated into a
peripheral portion formed of many layers, the volva, and a bluntly conical body
inclosed by the volva, the primordium of the pileus and stipe; both volva and primor-
dium of pileus and stipe are lost below in the bulbus. In the next stage the flat um-
brella-like commencement of the pileus appears at the apex of the primordium, being

CHAPTER V.—COMPARATIVE REVIEW.—HYMENOMYCETES, 293

„ covered by the volva and borne on the broad and stoutly conical stipe-primordium
(Fig. 135 a).

At first only the upper surface of the pileus appears distinct and separate from
the volva; then the commencement ofthe hymenial layer or the lamellae is seen in
the general shape of a narrow ring beneath the upper surface of the pileus and
separated from the volva by a layer of tissue, the future body of the pileus (4, c). All the
principal parts of the structure are now commenced ; the whole tuber has reached
a size of 10-20 mm., being irregularly ellipsoid in shape and having towards the apex
a deep depression with thickened and rounded edges, in the middle of which the
young pileus with the volva
forms a _ regularly shaped
cushion-like prominence. All
these parts are shown succes-
sively and sharply defined in
section, most sharply in a me-
dian longitudinal section, but
none of them with distinct
edges bounded by ever so
small a gap. The definition
is entirely due to the fact that
the structure is different in the
different parts; the young hy-
menium, the outer surface of
the pileus, and a strip which
runs vertically from this into
the middle of the stipe are
formed of slender hyphae and
have little air or none in the
interstices of the weft; they
thus have an aqueous trans-
parence and are contrasted
with the tissue round them,
which is white in colour from

* FIG. 135. Amanita rubescens, Fr. a—d radial longitudinal section through com-

the presence of broader inter- pound of di ages. S jive stages of development according to
a . 5 the letters. da small and nearly mature speci: fi secti a
stices filled with air and has inthe direction ofthe dotted line. ¢ thin jal longktndinal section through the

inflated hyphal cells among its Pmgunacuinemc Sey cree Delta pete
narrowly cylindrical elements, Sinn sahen Ce 2 meng and the ren
If the air is removed the sharp-

ness of the definition at once disappears. It should be particularly observed
that the hymenial layer, which received a passing notice above, is seen to be
separated into the future lamellae from the moment that it first becomes visible ;
these appear as plates of tissue stretching from the inner surface of the pileus to the
outer surface of the stipe. Brefeld observed in Amanita muscaria that there was
never anything more than a narrow space containing air between each pair of plates;
according to Woronin’s and my own previous investigations, especially into A.

rubescens, it is shown by tangential longitudinal sections that a narrow plate of air-

294 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

containing tissue lies originally between each pair of future lame] ae, which does not ,
however grow with them, but disappears as the general structure developes and thus
completes the delimitation of the surfaces of the lamellae (Fig. 135 g). The dispute
is not important and arises perhaps from specific differences. But there is no
question that the primordia of the lamellae have no free lateral margin; their
longitudinal margin on the side of the stipe passes into the tissue of the surface
of the stipe as continuously as the margin that looks towards the pileus passes into
the substance of the pileus.

The commencement of all the principal parts is followed by a general vigorous
growth throughout, and from this time the pileus and the stipe grow more rapidly
than the bulbus, the contrary having been the case in former stages. The portion of
the stipe above the bulbus, hitherto a Jow narrow disk surrounded by the commencing
hymenium, grows into a stout body slightly conically pointed at the apex, and the
growth of the young pileus and of the hymenium keeps pace so exactly, that the
attachment of the lamellae to the surface of the stipe, which has been already noticed,
is not interfered with; the pileus increases in size by superficial extension in the
direction of the margin, and the lamellae which are first formed increase
correspondingly in radial length in the same direction, and in breadth in the
direction of the stipe. The increase in breadth, however, is comparatively small, so
that the marginal portion of the pileus is somewhat curved over and bent downwards
(epinastically) in towards the surface of the stipe (Fig. 135 d). Lastly, as the general
surface of the hymenium becomes broader towards the margin in consequence of
this growth, new lamellae make their appearance between the original ones, being
distinguished from them only by the fact. that the edge towards the apex of the
pileus does not extend as far as the apex, while that towards the margin lengthens as
the margin advances ; the later they are formed the greater the distance from the apex
of the pileus at which they terminate. All this growth of pileus and lamellae
marginwards takes the same course as regards its direction as in the rest of the
Agaricineae ; but it does not result in the formation of free margins or even of
margins bounded by gaps. The various margins are bounded by undifferentiated
hyphal weft with intercalary growth and pass into it without any distinct boundary
line, and at the zone of transition the differentiation is constantly spreading over
newly formed sections of this weft.

These processes of growth and differentiation at length reach their limit, and
are followed by the final completion of all the parts, the last acropetal elongation of
the now tall cylindrical stipe and the hyponastic upward expansion of the pileus
—phenomena which again follow in their main features the same course as in the
species previously described. There is only one more peculiarity to be observed in
the Amaniteae, namely, that the peripheral layer of the stipe into which the edges of
the lamellae pass, a thick loosely felted layer, takes no part in the elongation of the
inner portion of the stipe which it encloses. It separates everywhere as the
elongation proceeds from the surface of the stipe, retaining its connection with it
only at the point of insertion of the pileus (Fig. 135 d); it also continues at first in
connection with the edges of the lamellae, forming a continuous membrane which
extends over the whole surface of the hymenium up to the margin of the pileus. As
the pileus expands the connection is dissolved, beginning from the margin of the

CHAPTER V.—COMPARATIVE REVIEW.—HYMENOMFCETES. 295

pileus, until at length the entire membrane is attached only at the uppermost end of
the stipe and hangs down from it like a frill, being cone-shaped and broadening
downwards, and plaited in delicate folds corresponding to the former lines of contact
with the lamellae ; in this state it is known as the annulus superus, frill or armilla.

It remains to remark that the volva slowly follows the growth of the pileus,
partly by increase in size of its cells, partly also during a certain period by a not very
copious formation of new cells. This growth continues longest in the inner layers
next the surface of the pileus, while the outer, which cease to grow earlier, are
consequently torn and rent in pieces. At length it ceases altogether, and when
the stipe begins to elongate greatly the volva tears all round where the margin
of the pileus and the bulbus meet and is split up over the top of the pileus into
the angular pieces which lie loose on the ripe pileus of Amanita muscaria, and look
like white warts.

Amanita vaginata and some species of Volvaria appear, from the few data with
which we are acquainted, to have the same or very nearly the same development as
the forms just described, except that they form no armilla, the lamellae and the
margin of the pileus separating smoothly from the stipe at the time of upward
expansion, and that the volva is ruptured at the apex and hangs together at the base
of the elongated stipe as a sac opened by lobes.

The following remarks are added to the above account by way of illustration.

1. The account given above of the development of the species which are furnished
with a marginal veil is founded, wherever it departs from my former statements, chiefly
upon the facts discovered by Hartig and Brefeld. It so far differs from the interpretation
of these facts expressed by Brefeld, that it acknowledges the existence of only a marginal
veil in the Coprini, Coprinus stercorarius for example and C. lagopus, whereas Brefeld
thinks that these species have a volva like that of Amanita. This difference of
opinion arises from the fact not mentioned above, that the apex of the pileus in
these species is covered with hair-formations, with which the hyphae of the marginal
veil are so interwoven that the two together form a dense covering over the young
pileus, and also that in some species the veil itself and the surface of the young
stipe are overlaid by a similar covering of hairs. The hairs begin to be developed
in the earliest stage of the formation of the pileus; in etiolated specimens! on the
top of the primordium before or without the downward growth of the hyphae which
build up the margin of the pileus. They grow out from the pileus and multiply, that
is, the members of the cell-rows of which they are composed are developed in
progressive succession towards the future definitive surface of the pileus, and from
it new cells are added one after another to the hairs already formed, and new
hairs are inserted between the original ones. To this must be added in many
cases the resemblance in form between the hairs of the pileus, the constituents
of the veil, and the clothing of the stipe. All are in the young state cylindrical
hyphae; all may retain this form during their existence, as in Coprinus lagopus? ;
or the segments swell as they mature into round vesicles, and the hair assumes
the appearance of a rosary and the cells part from one another as they grow
old. A desquamating covering of hairs of this kind clothes pileus and veil and stipe, as
in C. ephemeroides and C. micaceus. The covering of hairs generally ceases to grow
before the upward expansion of the pileus and final elongation of the stipe, and

! Brefeld, Schimmelpilze, III, t. IV, Fig. z.
2 Ibid. t. VII.

296 DIVISION II.—-COURSE OF DEVELOPMENT OF FUNGI.

is ruptured and torn by these processes in different ways according to the species
and thrown off by the more or less sharply defined and more persistent tissue of
the definitive surface of the pileus. These are all facts which remind us of similar
ones in the volva of Amanita. Here too no clear distinction can be drawn between
hairs and hyphae. This is the case with the Fungus-bodies generally; when we
speak of hairs in the Fungi we always mean parts of hyphae of special form
and arrangement. The peripheral elements in the species of Amanita may if necessary
be also termed hairs. But the difference already pointed out in the first stages of
the formation appears to me decisive in favour of the account given above. In
Coprinus the apex of the pileus is first formed, and then the hairs sprout out from it.
Brefeld’s figures of C. lagopus show this clearly, and it strikes the eye especially,
when, as in C. stercorarius, the hairs of the surface of the pileus have an entirely
different form from those of the stipe and marginal veil’. In Amanita, on the
contrary, the parts in question separate from one another 2” the previously formed
uniform compact primordial hyphal tissue by differentiation, that is, by difference
in the further development. The distinction remains unaltered, though the effect,
the practical use if we may say so, is the same in both cases, namely, the formation of
a protecting envelope for the young growing pileus. Still less is it affected by Brefeld’s
query, why the pileus of C. lagopus should indulge in the luxury of forming hairs
from which it gains nothing but the trouble of getting rid of them again. For the
situation remains the same in this respect if instead of hairs we say volva, or if it
really were a volva; and hairs or oftentimes a close felt of hair are found as a protecting
covering in an infinite number of cases, not only on the pilei of Fungi, but on all possible
parts of plants during a certain portion of the young state, and are thrown off before
the parts are unfolded.

2. In the case of Amanita Brefeld’s and my own previous statements complete
one another without any important differences of opinion. Our direct observations
on the first separation of pileus and volva would not in themselves be sufficient to
establish with entire certainty the marked distinction which has been pointed out
above between this genus and the forms with a marginal veil; it would still be
possible that the volva is formed in the same way as the envelope in the Coprini
or in Agaricus melleus, and that the contrary conclusion arose from the unsuitableness
or minute examination of the scanty material at the disposal of the observer, which
must be laboriously collected in our forests. But that the processes are really different
may certainly be gathered from the development of the lamellae, for which it is much
less difficult to obtain suitable materials and preparations. Ocular inspection also
in conjunction with the facts thus established scarcely leaves a doubt as to the
correctness of the view here proposed with respect to the first separation of the volva.

3. The final result of the development as exhibited in the expanded pileus is always
the same in the truly gymnocarpous forms whether they have a marginal veil or a
volva. This circumstance makes it probable that intermediate forms are to be found
in the long series of the Agaricineae connecting the three types here distinguished.
The conjecture finds support in a comparison of the forms described above ; Agaricus
melleus with its marginal veil comes nearer to the gymnocarpous forms than the
closely enveloped Coprini, which rather approach the Amaniteae in the character
of the envelope, though the difference before insisted on still remains. More extended
and searching investigations may be expected to add to the number of intermediate
forms. According to former statements of mine a further phenomenon of an inter-
mediate character occurs in some species with the marginal veil, in which the com-
pound sporophore is at first a small undifferentiated tuber as in Amanita, and then
a Narrow space containing air, a horizontal annular slit, appears in the interior of the

E 1 Brefeld, Schimmelpilze, ITI, t. II, Figs. 2-4, &c.

CHAPTER V.—COMPARATIVE REVIEW.— HYMENOMFCETES. 297

part which is afterwards the upper extremity of the stipe; the part above the slit
becomes the pileus, that below it the stipe, and that which bounds it on the outside the
marginal veil. The further development is the same as that of the species with
marginal veils described above. So far as these statements related to Coprinus, they
have been shown by Brefeld’s researches to be incorrect ; my own did not pay sufficient
regard to the earliest stages of the development. I will not even maintain that they
are quite correct for Agaricus campestris and A. praecox, but readily allow that the
facts in their case are always the same as in A. melleus and that the first extension
of the marginal veil over the hymenial surface which was originally exposed had
there also been overlooked. At all events the question should be further investigated.
I bring forward these earlier statements chiefly to show how we may picture to
ourselves the phenomena which wouid be intermediate between Amanita and
species with a marginal veil, the modes in which differentiations may be combined
with subsequent progressive growth of free margins bounded by gaps in the pileus
and lamellae.

4. With the exception of certain special cases arising out of the circumstances
just described, all, or very nearly all, the veiled forms here mentioned may be arranged
under the chief types specified in the text. The origin also of peculiarities like the
annulus mobilis in the comparatively few cases in which it occurs, as in Agaricus
(Lepiota) procerus, can scarcely be different from that in Coprinus ephemeroides.

Information as to the presence or absence of the volva in the several species or
groups will be found in descriptive works. It appears to be found only in the
groups Amanita and Volvaria and the peculiar genus Montagnites, a form of the
Agaricineae which is distinguished by the absence in the mature state of a proper
pileus and which requires investigation. The lamellae in the latter case are radially
disposed round the upper and somewhat broader end of the cylindrical stipe which
projects from out of a volva!.

Examples of marginal veils are supplied by the Coprini which have been described
above, by the groups Lepiota, Armillaria, Pholiota, Hypholoma, Psalliota, &c. in the
Agaricineae, and by Boletus luteus, B. elegans and their nearest allies. All species not
belonging to the Agaricineae, the non-fleshy species among the Agaricineae and the
fleshy ones of the divisions Mycena, Clitocybe, Omphalia, Pleurotus, Paxillus, Gom-
phidius, Lactarius, Russula, Cantharellus, Nyctalis, are, as far as can be ascertained,
truly gymnocarpous. Other groups or genera which are at present considered distinct
contain gymnocarpous species and species with a marginal veil. The group of
Boletus luteus is an instance of the kind. Among the Coprini, which otherwise agree
so closely together, Coprinus ephemerus is distinguished, according to Brefeld, from the
species described above by the entire absence both of a veil and of the dense covering
of hairs ; in place of the latter only short, scattered, conico-cylindrical hairs are found
on the surface of the pileus and stipe.

Some species of the section Collybia for instance, Agaricus dryophilus, A. tuberosus,
and A. cirrhatus are gymnocarpous, while others, according to Hoffmann, as A. velutipes
and A. fusipes, have marginal veils. Similar differences are found among the Cortinarii,
Hygrophori, and others. We are still without comprehensive and certain knowledge
of all these circumstances, nor have the various formations described from time to time
as vela ever been critically examined; a more thorough investigation of these points is
therefore to be urged now as it was twenty years ago.

Section LXXXVII. The structure of the mature compound sporophores,
excluding from consideration the hymenial layer which will be specially noticed here-
after, in perhaps all non-fleshy and many fleshy forms is always ‘ hyphal’ (‘fadiger’), and
the general rules specified above in section XIII are applicable to it. Exceptions and

! Corda, Icon. VI, t. XX ; Explor. sc. d’Algerie, t. 21.

298 DIVISION II.— COURSE OF DEVELOPMENT OF FUNGI.

details will be found in special descriptive treatises and in Hoffmann’s, R. Hartig’s
and Brefeld’s anatomical works. Most Tremellineae are distinguished by the
circumstance that their whole body, except a thin cortical layer at most, consists
of gelatinous tissue capable of the utmost degree of swelling. See above, pages
g and 12.

The structure of some fleshy species is partly pseudo-parenchymatous, and this
is associated with other and peculiar appearances. The characteristic composition
of almost all parts of the Amaniteae out of slender confusedly woven hyphae
and inflated bladdery cells, which are segments of the hyphae, has been already
mentioned. The volva also has the same structure, and is thus distinguished from the
surface of the pileus, which continues to be formed of slender closely compacted
hyphae, and in A. muscaria assumes the character of a gelatinous felt. Further
instances of a structure which departs from that of simple hyphal filaments are seen in
the Russula, Fr. and Lactarius, Fr. groups of the Agaricineae, and a description of
them may be reproduced in this place.

The compound sporophores in these Fungi are round umbrella-shaped pilei with a
thick central stipe, and they are of a firm fleshy consistence.

Sections in different directions through the pileus and stipe of Russulae, which were
examined in the case of R. integra and R. olivacea by Bonorden, and in R. integra,
Fr., pileo rubro and R. adusta, P. by myself, show two different kinds of tissue in
all parts, except in the outermost surface, which is formed of a close weft of slender
hyphal filaments sometimes and in some parts of a gelatinous consistence, as, for
example, in the pileus of R. integra. There are large groups of broad, pellucid,
roundish cells, and riband-like strands composed of slender branched hyphae which
contain an abundance of protoplasm. The pellucid groups of roundish cells have an
irregularly elongated shape in the stipe with rounded or pointed extremities, the longer
diameter being parallel to the.stipe. In the fleshy substance of the pileus they are
roundish and irregularly disposed. The slender filaments of the plates and strands
grow round them in every direction and in such a manner that the former appear on a
cross section as an irregular network, the meshes of which are filled by the round-
celled tissue. The arrangement of the cells in the Jatter shows no fixed order in the
middle of the stipe and in the pileus ; towards the surface of the stipe they are placed
in irregular horizontal rows or layers. The size of the groups and that of the individual
cells gradually diminishes from the middle to the surface of the sporophore, while the
thickness of the bands of slender filaments increases. The fibrillation in the stipe is
chiefly longitudinal, but follows no rule in the pileus. Branches separated from their
hyphae may be seen to enter the round-celled tissue from all parts, and branch
irregularly and spread in it. Closer observation of sections in which the filaments
have been unravelled makes it quite plain that the round cells are connected in such
a manner with the hyphae that are woven round them and spread among them, that
they must be members of greatly enlarged branches of these hyphae with the form of a
rosary; transition-forms also may be seen between the truly round cells and the narrow
cylindrical members of the hyphae which have grown between them and around them.
Bonorden was the first who called attention to this point; in others the connection and
development of the two kinds of tissue still require more careful examination.

The structure of Lactarius has been investigated by Bonorden principally in
Lactarius pallidus, by Hoffmann in L. mitissimus, and by myself in L. subdulcis, L.
chrysorrhoeus, and L.deliciosus. Here, as in Russula, there are groups of broad roundish
cells which appear to be set in a weft of slender cylindrical hyphae (Fig. 136). The
superficial or cortical layer is formed of the latter only. The large-celled groups have
much the same shape as in Russula, but they are usually narrower and more sharply

CHAPTER V.—COMPARATIVE REVIEW.—HYMENOMYCETES. 299

defined than the strands of slender hyphae; they are often much elongated in the
stipe and not unfrequently branched in the longitudinal direction or anastomose with
others. In transverse sections, especially in the stipe, the cells of many of the large-
celled portions are ovoid or wedge-shaped, and are so arranged, usually five or six
together, round a centre that their narrow ends converge towards it, and they thus
form a rosette on the transverse section. The cells thus arranged either form the
large-celled group by themselves, or they are surrounded by one or more irregularly
concentric layers of roundish cells ; other groups show two rosettes in the transverse
section, others again show no indication of arrangement in rosettes. The small
circular centre of the rosettes is formed by the transverse section of a narrow,
cylindrical, thin-walled hypha with limpid cell-contents, which runs longitudinally
and usually in a very winding course through the groups of large-celled tissue, as
appears in a longitudinal section. The laticiferous tubes which are characteristic of
Lactarius run through the strands of fine hyphal tissue, both close beside the large-
celled groups and at a distance from them, but without ever entering them. These
tubes have a large diameter as compared with that of the surrounding hyphae and a

>

>
a So
Le
RR

xy
X

X

ly
3

ise
4)
RR

y
h

TAN
i

Za
ZN
m

FIG. 136. Lactarius subdutcis, Fr. Outer region of the stipe. al I section. 5 section ;
o surface ; 2 laticiferous tubes. Magn. go times.

very soft and extensible membrane, and they are filled to overflowing with a finely-
granular turbid latex which is differently coloured in the different species and oozes
out in large drops from the injured Fungus. The latex coagulates at the temperature
of boiling water and when treated with alcohol. It is therefore advisable in examining
the course of the tubes in sections to place the Fungi for a short time in alcohol ; in
order to make preparations through the isolated tubes, the parts of the Fungus should
be previously boiled a short time in water. Such a preparation shows that the tubes
send out numerous strong branches in every direction, which often form H-shaped
connections between two primary tubes, but never give rise, as far as I have observed,
to a net-work with narrow meshes. Here and there the stronger branches put out
short and delicate branchlets with very slender closed blind extremities. In older
specimens especially the laticiferous tubes are not unfrequently divided by single septa
placed at a considerable distance from one another. These organs traverse the hyphal
weft of the whole of the compound sporophore and their finer branches extend to close
beneath its surface.

300 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

The foregoing account agrees in the main with Hoffmann’s statements, only that
observer describes an intercellular passage in the centre of the rosettes instead of
the winding hypha, which it resembles in shape. In the species which I have
examined the intercellular passage has evidently a wall of its own, which is even
separated here and there by intercellular spaces from those of the adjoining cells ;
this is shown with more than usual distinctness in Lactarius subdulcis and L. deliciosus ;
but it is possible that the species differ from one another in this respect. The structure
in Russula foetens var. lactiflua, Corda! is certainly very like that here described. I do
not attempt to determine what is the cause of the difference between Corda’s account
and the one in the text above. Schleiden’s statement that the latex of Agaricus
deliciosus is ‘decidedly contained in small groups of parenchymatous cells’ is quite
unfounded, and the same may be said of Kiitzing’s? confused account of these parts.

It may not be out of place to state here, that laticiferous tubes or long-membered
hyphae have also been found by De Seynes in striated hyphal tissue of the sporophore
of Fistulina hepatica, which otherwise is uniform in structure. Similar organs, that is,
long tubes filled with dense and often glistening cell-contents, occur in some other
fleshy mushrooms, especially Agaricineae, as in Agaricus praecox and A. olearius
according to Tulasne ; they require further investigation.

Formations of a peculiar kind were found by Hoffmann’ on the armilla of Amanita
muscaria, but have been searched for in vain in allied species. The outer surface of
this organ is covered by a thin layer of a yellowish greasy structureless substance.
If this is placed in water a number of microscopically small bodies, with a glistening
oily appearance and with the shape of small cylindrical rods ending usually in a knob,
emerge quickly from it. They display a lively undulating and trembling movement,
and changes of form such as elongation and abbreviation, forming of loops, and so on.
If left to the effects of the water they cease to move after twenty-four hours or some
longer period, and generally, but not always, assume the form of hollow spheres with
a wall glistenting like oil and watery contents. These bodies consist of a fatty or
resinous substance soluble in alcohol and ether mixed with a small quantity of
another substance not soluble in those fluids and turning yellow with iodine. They
resemble in appearance the motile formations observed in Beneke’s myelin (protagon-
mixtures)* when placed in water. There is no reason to suppose these rods to be
special organs of Amanita muscaria. The substance from which they are developed may
perhaps be a product of decomposition of elements of the tissue, which were destroyed
by the expansion of the pileus.

Section LXXXVIII. As regards the structure of that part of the sporophore
which bears the hymenium, and which sometimes receives the special name of
hymenophorum, it is to be observed that the hymenium itself consists of the basidia
and the cells which accompany them, and that both are the terminal members of
copiously branching hyphae and are placed in a vertical position on the hymenial
surface. The description in section XII of the construction of the sporophore
generally applies equally to the structure, interlacing, and direction of these hyphae
at the commencement of their course. Their ramifications become more numerous,
delicate and compact the nearer they approach the hymenium; immediately under-
neath it they are excessively abundant, more rich in protoplasm than the rest of the

1 Corda, Icon. IV, t. X.

2 Phil. Bot. I, p. 247.

3 See Bot. Ztg. 1853, p. 857, and 1859, p. 212. De Bary in Flora, 1862, p. 264. Fr. Darwin
in Quart. Journ. of Micr. Sc., new series, XVIII (1878), p. 74.

4 See Beneke, Studien ii. Gallenbestandtheile, &c., Giessen, 1862.

CHAPTER V.—COMPARATIVE REVIEW.—HYMENOMYCETES, 301

tissue of the sporophore, and closely interwoven and united with one another. In
more simple forms, as Hypochnus centrifugus, Tul. (Fig. 137) and the Tremellineae,
they may still be separated from one another for considerable distances; but they
usually form a delicate tissue very difficult to
unravel, which is distinguished by the name of
the subhymental layer or subhymenial tissue.
Where the hymenial surface is furnished
with projections of definite forms, these pro-
jections and the spaces between them are covered
uniformly by the hymenium and the subhymenial
tissue. Only the outermost free margin of the
projections, the edge therefore of the lamellae, the
orifice of the pores, the tip of the spikes, is in
many species not covered by the hymenium. The
inner portion of the projections which bears the :
subhymenial layer is named the /rama (also dis- Ba a ogthe Gamlbcatione of he
. . E A pha, the branches of which form a tuft; at x an H-
sepiment or intralamellar tissue). The trama in shaped anastomosis. Magn. 390 times.
by far the largest number of cases is distinctly
hyphal in structure, and consists of a hyphal mass of the form of the projection,
in which the hyphae arise as branches of those of the sporophore along the
whole line of insertion of the projection, enter
it at its base in a straight or curved line,
and run from thence to its free margin in a
course parallel to the surface. The trama there-
fore usually exhibits a distinctly marked fibril-
lation running from the line of insertion to the
free margin, as in many Agarici (Fig. 138),
Lenzites, species of Polyporus, Trametes Pini,
Hydnum zonatum, H. cirrhatum, H. gelatinosum,
and in Boletus edulis. The separate hyphae in
the trama pursue a straighter or more undulating

Wd

nT

and winding course according to the species. It AN

is more unusual for the trama to be composed Al
A . . CAN SS

of a tangled hyphal-weft without definitely di- a S

rected fibrillation, as in Polyporus hirsutus and

P. annosus (see on page 57). The structure,

consistence, colour, &c. of the constituents of the ic. 138. Agaricus vulgaris. A semi.diagram-
trama are either the same as those of the rest ee ee ee
of the sporophore or they may be different from Geese 9, WE Rise conttng of san gelatinous
them, as a glance at the generic characters in mann trama.ot

the.Hymenomycetes is sufficient to show. Sub-
hymenial tissue and hymenium spring from the trama in the manner specified
above ; the elements of the hymenium are everywhere perpendicular to its surface.

The trama of the lamellae in the group or genus Lactarius shows the structure just
described, at least in the case of L. subdulcis and L. chrysorrhoeus which I have
myself examined. The groups of large-celled tissue become suddenly fewer and

302 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

smaller towards the under surface of the pileus or hymenophorum ; this consists itself
of numerous layers of hyphae which run in an undulating course from the middle of
the pileus to its margin and give off the hyphae of the trama as branches. The
subhymenial tissue is composed of small isodiametric cells, which show plainly by their
arrangement that they are members of the delicate short-celled interwoven hyphae.
The laticiferous tubes appear both in the hymenophorum and in the trama; in the
former they usually run parallel to the principal hyphae, while in the trama they spread
in abundance in every direction and are much branched. The structure of the trama
in Russula, and according to Hoffmann in Lactarius mitissimus also, is for the most part
pseudo-parenchymatous.

Schizophyllum, a genus of the Agaricineae, differs from the rest in the structure of
the lamellae. The lamellae are formed in this case, as in other genera, as projections
from the hymenial surface, but they split from the edge to the middle parallel to
the surfaces into two plates which curve away from one another as they continue to
grow. The dorsal surfaces which are convex to one another are sterile and hairy with
spreading hyphal branches ; the concave surfaces answering to the surfaces which bear
the basidia in undivided lamellae with the interstices between them bear the hymenium.
Fistulina so far agrees with Schizophyllum that its hymenium is beset with small
tubes, which bear the hymenium on their inner face and are barren without; only the
tubes are formed separate from the first, according to the accounts which we possess,
and not by the splitting of the trama of reticulately connected projections.

The hymenial layer itself consists of the terminal members of the subhymenial
hyphae closely packed together and placed vertically to the surface. The larger
number of these cells develope into basidia. Others may remain sterile and then
they surround the basidia as the paraphyses surround the asci and may there-
fore be called by that name. They appear to be the hymenial tissue of Léveillé
which he distinguishes from the basidia in his fundamental researches into the
hymenium of the Mushrooms. It is uncertain whether they can be entirely
wanting; yet it has been expressly stated by more recent observers that in some
cases the hymenium contains only basidia, for example by De Seynes in the
case of Fistulina hepatica, and many other descriptions say the same thing by
implication inasmuch as they speak only of basidia. The fact is that in many cases
amongst undoubted spore-abscising basidia there are present only structures that
may possibly prove to be paraphyses, but which are so very like the basidia, differing
from them at most in their somewhat smaller size, smaller amount of protoplasm and
present sterility, that it is not possible to say when they are examined in prepared
specimens whether they might subsequently have assumed the function of basidia or
not. This is the case with Agaricus melleus!. From these circumstances the organs
in question have often been termed séerdle basidia, a name descriptive of the
appearance in all cases, but requiring critical examination.

On the other hand, cases are known in which the elements between the basidia
differ from them entirely in their character. The bowl-shaped compound sporophore
of Corticium amorphum, Fr. may be mentioned especially in support of the expression
paraphysis, in which a few long club-shaped basidia are found between a large number
of narrowly filiform branched hairs often constricted into the form of a rosary, so that
the sporophore would be thought at first sight to belong to a Peziza rather than to a
Hymenomycete?. It has long been known that the larger portion of the surface of

1 Hartig, Krankheiten d. Waldbäume, t. II. 2 Hartig, l.c. t. V.

CHAPTER V.—COMPARATIVE REVIEW.—HYMENOMPCETES. 303

the hymenium in Coprinus, while maturing and when mature, is covered with
irregularly 3-5 angled prismatic almost isodiametric cells of uniform height and with
pellucid contents. The much narrower basidia are inserted without interruption
between the corners of these paraphyses-cells, alternating therefore with them, and it
is only rarely that the corners of two paraphyses meet together (Fig. 139).

Other formations occur not unfrequently, different from these paraphyses-forms
and in certain cases at least close beside them, which are generally distinguished from
them by the circumstance that they stand out as large unicellular structures far
above all others on the hymenial surface. As they are often inflated in appearance
in the fleshy species Léveillé named them cyszdia; Phoebus called them specially
paraphyses.

The eystidia according to present accounts have been found in species of all the
groups except the Tremellineae, Clavarieae, and Hydneae, but so distributed that
their presence or absence and their relative frequency of occurrence vary according

FIG. 139. Coprinus micaceus, Fr. aa thin longitudinal section through the upper surface of a lamella, the
basidia distinguished by their turbidly granular contents and springing from the subhymenial cells between
pellucid inflated ; pa idii 5 surface-view of the i The intercellular space between
two paraphyses to the left above appears by a mistake in the woodcut, but was not shown in the drawing from which
the woodcut was taken. Magn. 390 times.

to the species within narrow cycles of affinity. While they are wanting, for instance,
in most of the non-fleshy Polypori, they are found in Polyporus igniarius and Trametes
Pini; while they are abundant in most Coprini they occur rarely or not at all, according
to Brefeld, in Coprinus ephemerus. They originate like the basidia in the subhymenial
tissue and their position is the same as theirs; but sometimes, as in Trametes Pini
and Lactarius deliciosus, they terminate special branches of hyphae which ascend
to the hymenial surface from the interior of the trama without directly bearing
basidia also. They are sometimes scattered without order over the hymenial surface,
more frequently they are found on the free margin of the hymenial processes, especially
on the edge of the lamellae in the Agaricineae. Their number is usually small
compared to that of the basidia, often very small; but in species of Stereum which
Léveillé named Hymenochaete! (S. rubiginosum and S. tabacinum) the hymenium,
owing to their presence, has the appearance of being covered with bristly hairs.

1 Ann. d. sc. nat. ser. 3, V (1846), p. 150.

304 DIVISION IT.—COURSE OF DEVELOPMENT OF FUNGI.

Their shape and size vary in the different species; they are usually constant and
characteristic in each species, less so in genera and subgenera. The large, ellipsoid
or elongated, obtuse vesicles of the Coprini, which strike the naked eye, are remarkable
forms which require to be especially mentioned (Fig. 139). In a number of other
species they are cylindrical, club-shaped or flask-shaped, blunt at the extremities in
Polyporus umbellatus according to Corda, and in Agaricus viscidus, L. according to
Phoebus, or pointed, or with a knob in Lactarius, Russula, and Boletus according to
Corda; Agaricus fumosus, P. and A. laccatus, Scop. &c. have simple or branched
cylindrically hair-shaped cystidia according to Hoffmann; in A. Pluteus, P. they are
flask-shaped and furnished at the upper extremity with several short sharp projections
which are bent a little backwards into the shape of a hook!. In most of the
leathery or woody species in which they occur they are narrowly conical in form with
sharply pointed extremities which stand out prominently ‘like lance-points’ from
the hymenium, as in Stereum, species of Corticium, Trametes Pini, Polyporus
igniarius, &c.

The structure of the cystidia is as follows. In the species with a juicy flesh
a thin and usually colourless membrane encloses the colourless cell-contents which
are either protoplasm with vacuoles or quite transparent. I found in cystidia from
half-matured hymenia of Coprinus micaceus (Fig. 139 2) a central irregularly elongate
protoplasmic body, from which numerous branched anastomosing threads with active
amoeboid movement radiated to the wall; older cystidia in the Coprini are almost
perfectly transparent. In Lactarius deliciosus and allied species the cystidia are filled
with densely granular opaque contents. In this respect they resemble the laticiferous
tubes, and in thick sections it often looks as though they were branches of these
tubes, especially as they extend in this species far below the subhymenial tissue into
the interior of the trama. But I always observed that they sprang as branches from
non-laticiferous hyphae of the trama. The cystidia are of a deep purple-red colour in
Agaricus balaninus, Berk.? In the conical cystidia of the non-fleshy species the
membrane, especially in the projecting extremities, is strongly thickened and coloured
to correspond with the rest of the tissues.

Further details will be found in special works on the Hymenomycetes, especially
those of Corda, and in a separate work on the cystidia by H. Hoffmann, and in R.
Hartig’s writings.

According to Corda and the doubtful statements of earlier observers, the cystidia of
the fleshy Fungi discharge their contents in the form of drops through the apex which
is open in the figure. Neither I nor Hoffmann nor Brefeld were able to satisfy
ourselves that this was done spontaneously ; it was but rarely that I saw the cystidia
burst when placed in water, and according to Hoffmann this takes place quite
irregularly. The moist surface, which often bears small drops of liquid, is a phe-
nomenon which it has in common with all free Fungus-cells that are rich in cell-sap.

It is plain that the formations above described in the non-fleshy forms belong to the
same category as those in the fleshy ones, for there is no other more general difference
between them than that between fleshy and non-fleshy species. It is as little to be
disputed that the cystidia belong morphologically to the category of hair-formations,
one may say indeed that they are prominent hymenial hairs.

! Ditmar, in Sturm D. fl. III, 1, t. 28.
? Montagne, Esquisse org. et phys. de la classe des Champignons.

CHAPTER V.—COMPARATIVE REVIEW.—HFMENOMFCETES. 305

What function they have as hairs is still a matter of enquiry and is perhaps different
in different cases. Brefeld’s suggestion is best worth considering, that they serve to
protect the sporogenous basidia, and perhaps take part in the Agaricineae in loosening
the appressed lamellae from the stipe. That they and especially the strikingly large
vesicles of the Coprini were taken by the old observers’ for male sexual organs, and that
this notion once put into print was repeatedly being discussed for more than a hundred
years is a matter now only of a certain historical interest. The terms antheridia,
anthers, Zollinaria owe their origin to these views. Further details respecting them
will be found in older treatises on the formation of spores in the Basidiomycetes
(see page 116), especially in Phoebus, in Tulasne®, and in the first edition of this book at

page 170.

The basidia themselves, and the formation of spores on them, have been already
described in chapter III, pages 63, 64. We have only to add here that the club-
shaped form of basidium putting out 2-4 sterigmata at its upper end, such as
is represented in Figs. 28 and 30, and spores varying from round to fusiform,
are found in all the Hymenomycetes which have been examined, except the Tre-

SEHE NIEREN

EDEN

Ce

\

FIG. 140. a—d Auricularia Auricula Fudae. Basidia and formation of spores. Successive stages of the de-
velopment Ferse the figures. a a cylindrical terminal cell of a hypha, from which, 4, several definitive basidia

ions ; each of the basidia sends out a long narrowly conical sterigma, c, d, from its upper
extremity, and the swollen apex of the sterigma is abjointed to form a spore; x a sterigma from which the spore
has dropp J Exidia spic Devel of basidia. Four basidia have been formed from the
cell # by cruciform division, Younger and later stages of development are shown in the other parts of the figure:
saspore. The dotted lines indicate the surface of the hymenium. a—d magn. 390 times, /after Tulasne, highly

magnified.

mellineae. The members of the latter group are distinguished by their variations
from the general rule (Fig. 140). But there are intermediate forms. Dacryomyces,
Calocera, Dacryomitra, Guepinia, and other genera have basidia which produce
two spores and are distinguished from typical Hymenomycetes (Fig. 28) only by
the sterigmata; these spring from a comparatively broad base and are so finely
drawn out and to so great a length that the:basidia appear to have long pointed
bifurcations. But these forms afford no ground for a more decided separation of the
Tremellineae from the other Hymenomycetes. Tremella, Exidia, and Tremellodon

” Micheli, Nova plant. genera.—Bulliard, Champ. de France, I, pp. 39-50.
? Carpologia, I, p. 163.

[4] x

306 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

have another form of basidium, as was first observed by Tulasne. Subhymenial
hyphal branches swell in these genera to a spherical or ellipsoid cell filled with
protoplasm, the initial or primary basidium. This cell then divides by vertical
longitudinal walls usually into four cells arranged as the quadrants of a sphere,
secondary or definitive basidia, each of which then puts out a long sterigma and abjoints
a spore upon it which absorbs the whole of its protoplasm. Slight variations occur
in the number of the secondary basidia formed from a primary. But more important
than these are the differences in the separation of the basidia, which may go so far
that before the spore-formation each of the three sister-basidia becomes separated
down to the base, or, on the other hand, all may remain united as at first; or again
the division of the primary basidium may be incomplete or be omitted, and the
basidium become imperfectly chambered or lobed, each division answering to a
sterigma ; this is the case, according to Tulasne’s account, in Tremella violacea and
T.Cerasi and in Sebacina incrustans, and according to Brefeld in Tremella violacea !.
Cases of the latter kind form the transition to the two-lobed or four-lobed basidia of
Dacryomyces and to ordinary Hymenomycetes,

In Auricularia Auricula Judae (A. sambucina, M.) the primary basidium is long
and cylindrical and very like the basidia of Dacryomyces and Calocera. It divides
by transverse walls into a row of four or five daughter-cells, each of which sends out
an erect subulate sterigma, which rises above the surface of the hymenium and
abjoints a spore. The sterigma issues from the apex in the uppermost basidium of a
row, in the rest from the side close beneath the upper wall; the formation of
sterigmata and the abjunction of spores begins in the uppermost basidium of a row;
the rest follow it in order from above downwards. Exactly similar phenomena are
described by Tulasne in Hypochnus purpureus, only the end of the row is in this case
hooked and the terminal cell itself is sterile. The shape of the ripe spore also is pecu-
liar, being renzform in most of the ‘Tremellineae. These characters necessitate the
separation of the Tremellineae as a special division of the Hymenomycetes. The
gelatinous constitution of the sporophore is a convenient character in many cases,
but would not be of sufficient importance by itself, the more so as Sebacina incrustans
and Hypochnus purpureus, the latter of which I have not myself examined, do not
appear to have gelatinous membranes,

By far the greater number of the Hymenomycetes form only one hymenial layer
on each sporophore, whether it is of only brief duration or lasts longer and even for
many years. The course of its development, the maturation of its parts, exhibit
in general the same progressive advance towards the margin and apex as has
been already described in connection with the growth of the whole apparatus which
bears the hymenium. A few slight deviations however occur. On the one hand,
the definitive completion and differentiation of the originally uniform elements of
the hymenium are effected, according to Brefeld, in Coprinus simultaneously at all
points of the hymenial surface; it has long been known that in C. micaceus and
C. comatus the ripening of the spores, as shown by the lamellae turning black, even
begins at the margin of the pileus and the edges of the lamellae and advances to the
middle of the pileus and the base of the lamellae. On the other hand, indubitable

1 See particularly the Ann. d. sc, nat. XV (1872), p. 234.

CHAPTER V.—COMPARATIVE REVIEW.—HYMENOMYCETES, 307

basidia have been found close to one another in very different stages of spore-
formation, or apparently younger basidia among full-grown ones on a small portion
of the surface of hymenia of moderate age in many Hymenomycetes. It would seem
as if the basidia which appear to be younger were of later formation than those which
are maturing, and had been subsequently introduced between them; in other words,
that an intercalary growth of the hymenium had taken place by insertion of new
elements, and the fact first mentioned of the juxtaposition of basidia in different
stages of maturity supports the idea of such intercalation. It is true that the first
formation of the basidia may have advanced strictly from the middle to the
margin of the hymenium, and only the last differentiation and maturation have
proceeded in a different direction; and the apparently young basidia may only have
been paraphyses which look like basidia. More thorough investigation of this point
is desirable.

In many long-lived Hymenomycetes the hymenial surface, which remains simple,
enlarges in each successive period of vegetation by the growth both of the whole
pileus and of the separate projections of the hymenium, the growth being in the
direction of the margin, as was described above on pages 56, 57. In old Polypori
which come particularly into consideration in this connection (P. fulvus and
P. igniarius and Trametes Pini) the older parts of the tubes formed in the earlier
years of the growth of the plant become stopped up, according to Hartig’s detailed
account, by a dense formation of hyphae in proportion as the tubes themselves
increase in length at the margin. The hyphae proceed from subsequent ramifications
of the hyphae of the wall of the adjoining tube, on which the peculiarly short
and very short-lived basidia performed their office a long time before and then dis-
appeared.

But a certain number of long-lived Hymenomycetes renew their hymenium in
successive periods of vegetation even on the same portion of its surface. A part only
of the parallel extremities of the hyphae which form the hymenium in the first period
developes into basidia or into cystidia also. Others, which do not differ in structure
from young commencing basidia, do not arrive at the formation of spores, but
remain capable of development and ramify and grow out in the next period of
vegetation beyond the first hymenial surface to form a new hymenium upon it, which
is similar to.the first and covers it everywhere. The old basidia and even their ripe
spores, and in a very striking way the acutely conical hairs or cystidia where there
are any, are overgrown by the new layer and enclosed in it. The process may be
repeated from period to period, from year to year. In this way distinct layers
corresponding to the years, or to shorter spaces of time periodically repeated, are
formed in hymenia by the remains of the basidia and hairs of each period; a few only,
according to Hartig, in Trametes Pini; the same observer counted 5-8 in Hydnum
diversidens, in Thelephora perdix as many as 20; I myself found as many as 6 on
not particularly old specimens of Corticium quercinum.

The question of ‘gonidial formations’ reported in some Hymenomycetes will be
deferred till section XCII in order to avoid repetition.

308 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

GASTROMYCETES.

Section LXXXIX. The Gastromycetes include the chief groups of the Hyme-
nogastreae, Lycoperdaceae, Nidularieae, and Phalloideae; to these are joined
a few smaller divisions composed partly of forms intermediate between them and partly
of divergent genera and some small groups.

The compound sporophores in these Fungi spring from a simple filamentous or
from a compound mycelium (see page 22). They are for the most part large, often
very large, bodies; Fig. 141 represents a beautifully small specimen of a small species.
When forming their spores they are all, with the exception of Gautieria, a genus of
the Hymenogastreae, receptacles or sacs entirely surrounded by a closed wall of
dense texture, the deridium or uterus, and usually divided inside by plates of tissue
springing from the peridium into chambers
in which the hymenium and the spores are
formed.

Gautieria has no peridium ; the chambers
in the periphery lie on the free surface and are
open to the outside. In all other forms the
peridium varies in thickness according to the
species and is often extremely thick; in many
cases it is largely and peculiarly differentiated,
partly into persistent, partly into temporary
parts, as will be set out at greater length
presently. It is a general occurrence in the
course of this differentiation that the peridium
becomes strongly, often very strongly, thick-
ened at the base, though there are exceptions
to this rule, as in Hysterangium and the

Fic. 141. Octavianta asterosperma, Vittad. Median Nidularieae. The thickened portion either
SEL, EGR ee Meee sca, © projects oulwards in the form of a ‘stipe
which bears the chambered portion, as in
Lycoperdon and Octaviania, Fig. 141; or it projects inwards forming a cushion, as
in Hymenogaster, Rhizopogon, Geaster hygrometricus (Fig. 146), or as an elongated
vertical central column, as in most species of Geaster (Vittadini), the Phalloideae
(see pages 316, 322) and others. The point of origin of the central column is termed
the base, because in all cases in which the earliest states are known it corresponds
to the point where the compound sporophore springs from the mycelium, and
generally also to the place of insertion of the full-grown peridium. In some forms,
as Rhizopogon and Geaster, mycelial strands run into the peridium at very various
and often at many points in the outer surface, and the first commencements are
not known; here therefore the expression base is only applicable by analogy.

Except in the Nidularieae and some divergent genera which will be specially
considered at a future time, the chambers inclosed by the peridium are narrow
irregularly curved and branched cavities, just large enough or too small to be seen
with the naked eye, and separated from one another by thin curved plates of tissue

CHAPTER V.—COMPARATIVE REVIEW.—GASTROMPFCETES. 309

which anastomose with one another in every direction and pass on one side into the
tissue of the peripheral peridium, on the other it may be into that of the central
column, seeming as if they radiated from it. The chambers of Polysaccum are larger,
of the size even of a pea, and are less irregular.

The chambers are in most cases in countless numbers; they form altogether
a mass of tissue which is distinguished from the adjoining tissue by its chambered
structure and by the formation of spores and is known as the gleba.

As regards the more minute structure, we may distinguish a middle layer or
trama in the walls of each chamber, and a Aymenzal layer, on both surfaces of the
trama. The two parts (Fig. 142) resemble in all essential points the parts of the
same name in the Hymenomycetes. In the cases which have been most thoroughly
examined (the Hymenogastreae, Phalloideae, Lycoperdon, Bovista, Scleroderma, Geas-
ter) the trama is formed of a weft of copiously branched hyphae, which chiefly run
parallel to the surface of the walls, and pass without interruption from one chamber-
wall to the adjoining ones and into the tissue
of the peridium. Numerous closely packed 4
branches from the hyphae of the trama run
towards the interior of the chambers, and there
form the hymenial tissue. In some cases they
are comparatively short, of uniform height and
placed palisade-like side by side and perpen-
dicularly upon the surface of the trama; thus
they form a sharply defined hymenial layer
which lines the empty cavity of the chamber
and is exactly like that of the Hymenomy-
cetes (very many Hymenogastreae (Fig. 142),
species of Geaster, Lycoperdon, Phallus). In
another series of cases (Melanogaster, Sclero-
derma, Polysaccum, Geaster hygrometricus),
all the hyphae which entera chamber from the _rıc. 112. Octaviantaasterosperma Vitt. Thin section
hymenium are elongated, copiously branched, Seh are, eg bras Geese Punt
and -woven together into a weft which fills a nn iileraika
the chamber. j

-The special formations also of basidia and paraphyses in most Hymenogastreae
scarcely differ at all from those of any Hymenomycetes except the Tremellineae. The
basidia of some Lycoperdaceae and Phalloideae, described already on page 63, vary
a little more from them, but only in points of special conformation. Those of Geaster
tunicatus and Tulostoma are strangely shaped objects; the former are ellipsoid to
flask-shaped vesicles with a narrowly conical neck, the apex of which puts out about
six sterigmata which abjoint spores; the latter (Fig. 143) are narrowly club-shaped
cells which abjoint four almost unstalked round spores on their lateral faces.

t. There is not much to add to what has been already said of the Hymeno-
gastreae. The gleba retains the structure which has been described from the
cominencement of its formation to its perfect maturity (Fig. 141). Its tissue is
all- the while either fleshy and formed of thin-walled juicy cells, the interstices
conveying ait or fluid, as in Hymenogaster Klotzschii, Tul. and Octaviania carnea,

310 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

Corda; or it is composed of a tough gelatinous felt, as in Hysterangium and
Melanogaster.

The peridia show no marked peculiarities of structure, having a close weft like
that of the walls of the chambers formed of hyphae which run chiefly in the direction
of the surface. They decay after the spores have ripened and while the gleba is
gradually becoming disintegrated.

The Secotieae, or at least the genus Secotium and Cauloglossum trans-
versarium, are Hymenogastreae in structure with a stipe and a thick central column
which traverses the entire peridium up to the apex in the line of prolongation of the
stipe (Fig. 144).

2. The young compound sporophores of the Lycoperdaceae, with whose
development we have any acquaintance (Lycoperdon, Bovista, Geaster), display
the structure of the Hymenogastreae in all important points up to the time of the
formation of spores, only the young peridium is developed on a much larger scale.
One point of difference makes its appearance at an early period; two kinds of hyphae
are formed in the trama when still young: slender delicate segmented hyphae rich
in protoplasm, which make up the chief mass of the trama and by their branches form

FIG. 143. Tulostoma mammosum, FIG. 144. Secotiumerythrocephalum,
Fr. Basidia with fully formed spores Tul Sporophore divided in half, of
highly magnified. After Schröter. the natural size. After Tulasne.

the constituents of the hymenium; and stouter tubes usually non-septate, which are
members or branches of the same hyphae as the delicate elements and run for the
most part in the trama, but may also, as in Lycoperdon and Bovista, send branches
transversely through the chambers from one wall to the wall opposite. When the
spores begin to ripen the delicate hyphae and the elements of the hymenium become
dissolved with copious effusion of water and entirely disappear. The thick tubes on
the contrary persist and grow, and acquire a shape and structure which vary in the
different genera and species, and their membranes become thickened and usually
assume a lively colour, yellow passing into brown. Together they form in
the compound sporophore, which ultimately becomes dry by the evaporation of
the water produced in it, a woolly mass of loose texture, the capzllitium, the
interspaces of which are filled with large quantities of a dry powder, the ripe
spores.

I include here under the name Lycoperdaceae all the species in which the
structure of the ripe gleba points to the above course of development, excepting only
for the present the genus Tulostoma, which will be considered below. They are

CHAPTER V.—COMPARATIVE REVIEW.—GASTROMYCETES. zıı

distinguished from other groups by the capillitium between the masses of spore-dust
in the ripe sporophore.

It has been already said that the peridium of the Lycoperdaceae is often of
considerable thickness and is much differentiated at ihe time of the formation of the
spores. The most important differentiation, which recurs in a variety of forms in the
different species, is the separation into an inner layer directly enclosing the gleba,
and an outer one which opens in different ways and becomes detached from the inner,
the zuner and outer pertdium of authors. The genus Geaster supplies excellent
examples of this. In Batarrea after the spores have ripened an axile strand of
tissue, beneath the middle of the inner peridium about a centimetre in thickness,
developes into a stout stipe, which may be as much as 2 decimetres in length and
raises the closed inner peridium above the outer which has opened irregularly.

The genus Scleroderma agrees in the structure of its sporophore up to the
formation of the spores with the Lycoperdaceae and Hymenogastreae, especially with
those in which the chambers of the gleba are filled with a tangled mass of hymenial
elements. Here too the hymenial tissue is dissolved and desiccation takes place
when the spores are fully ripe; the chambers remain filled with the dry powdery
masses of spores and the trama is disorganised, but persists as a dry fragile net-
work in which the original structure is indistinctly shown. No capillitium with its
characteristic structure is formed, at least not in the species examined by Tulasne
and myself. It is evident therefore that Scleroderma is intermediate between the
Lycoperdaceae and Hymenogastreae.

As regards the mode in which the Lycoperdaceae and Scleroderma form their
spores, the question raised by Berkeley in 18411, whether the spores always attain
their full development and maturity while still attached to the basidia, or whether they
do not mature till after the disappearance of the constituents of the hymenium and at
the expense of a portion of the products of disorganisation, as is the case in
Elaphomyces (see page 97), requires further investigation; Sorokin has recently
pronounced in favour of the second alternative.

3. If we imagine the entire number of the chambers in the compound sporophore
in Fig. 141 reduced to from twenty to thirty and each chamber comparatively large
regularly lenticular in shape and furnished with very thick walls, we get the plan of
the young sporophore in Nidularia. When ripe the outer wall-layers of the peridium,
except at the apex, and those which directly surround the cavity of each chamber
with its hymenium, persist as thick membranes consisting of many layers. The tissue
between these persistent layers becomes transformed into a jelly, and the wall of the
peridium also disappears over the entire surface of the apex. The ripe sporophore
therefore is an open bowl, in which the separate chambers as closed lenticular
receptacles (Zeridiola) are imbedded in mucilage and are at length set at liberty by
its disappearance. The genera Crucibulum and Cyathus exhibit the same
phenomena with a still greater diminution in the number of the chambers and an
augmentation of the transitory gelatinous tissue-mass; there is also a further
complication, inasmuch as each peridiolum remains attached inside to the persistent
wall of the peridium by a strand of tissue of complicated structure, which is likewise

} Annals and Magaz. Nat. Hist. VI, p. 431.

312 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

persistent. This separation of the peridiola in the opened bowl-shaped or cup-shaped
wall of the peridium is the distinguishing mark of the Nidularieae. Each peridiolum
is lined with a single hymenial layer which almost entirely fills the inner cavity ;
the basidia disappear after abscision of their spores, which are usually four in
number.

4. The Phalloideae, according to our present knowledge, have a comparatively
small gleba within a very massive peridial wall which is characterised by a gelatinous
middle layer. The structure of the gleba is, as in the Hymenogastreae, up tq the
formation of the spores; it has a great number of narrow chambers, and (except
perhaps in Ileodictyon ?) is traversed more or less completely by a thick central column,
from which the walls of the chambers radiate. Its entire tissue, with the exception of
the column, is disorganised when the small narrowly cylindrical spores are ripe, and
becomes a perfectly structureless mass of jelly which dissipates in water and, like the
spores, is of a dark-green colour. As the gleba developes a certain portion of the
peridial wall is transformed into a receplaculum in the narrower sense, which remains
at first in connection with the gleba, but becomes suddenly and greatly elongated at
maturity and carries up the gleba above the wall of the peridium which has opened
at the apex, and there allows it to deliquesce.

The conformation of the receptaculum is unusually different in the extreme cases.
One extreme is represented by Clathrus cancellatus and Ileodietyon. Here it is
formed in the inner layer of the peridial wall surrounding the gleba as a large hollow
body pierced so as to form a net-work or lattice-work. The gleba with the central
column which shares the gelatinous disorganisation of the gleba adheres to the
receptaculum at its final elongation and then breaks up and drops off. The other
extreme appears in Phallus and the allied forms; in these the receptaculum is a simple
fusiform body formed in the middle of the central column, which ruptures the ripening
gleba above its apex so as to form a conical cap and finally carries it up, in
consequence of its own elongation, above the ruptured apex of the peridium. The
two extremes are connected by a series of intermediate forms, the important points in
which are occupied by Clathrus (Colus) hirudinosus’, Aseroe’, Calathiscus*®, and
Aserophallus‘.

Phallus and its nearest allies are evidently the furthest removed from the rest
of the Gastromycetes. Comparison of early states, on the other hand, show an
unmistakeable and close agreement and affinity between forms such as Clathrus and
lleodictyon on one side and Geaster, a genus of the Lycoperdaceae, on the other. A
nearer connection seems to be established through the intermediate genus Mitremyces,
but this requires further proof.

Section XC. There are many undesirable lacunae in the history of the
development of the compound sporophores of the above four groups, chiefly owing
to the difficulty in procuring them in their early states. There is more than one cause
of this difficulty ; most species pass the first period of their existence beneath the

Tulasne, Explor. sc. d’Algérie, Fungi, p. 435, t. 23, ff. 9-22.

See Corda, Icon. fung. VI.

Montagne in Ann. d. sc. nat.-sér.-2, XVI.

Montagne et Léprieur, in Ann. d. sc. nat. ser. 3, IV (1844). See also Corda, Icon. Fung. VI.

CHAPTER V.—COMPARATIVE REVIEW.—GASTROMPCETES. 313

surface of the ground, while the attempts which have been made to cultivate them have
not been hitherto successful, and many of the most remarkable species grow in
countries which are very inaccessible to botanists.

However it has been ascertained that as a general rule every compound
sporophore consists at first of a close uniform weft of primordial hyphae, in which
the changes which produce its definitive condition are effected by internal differenti-
ation and new intercalary formations. The case may possibly be to some extent at
least different in Gautieria.

The differentiation begins chiefly with the separation of the gleba and the young
peridium and varies, as might be expected, in its further details according to the species
or genus and group. The most important of these details will be given in the
succeeding paragraphs together with the most remarkable peculiarities that have been
observed in the structure of the mature compound sporophores, and some additional
and critical remarks will be appended.

1. Hymenogastreae. Hymenogaster Klotzschii appears not unfrequently along
with Octaviania carnea during the winter months on heath-mould in flower-pots in
conservatories, growing at first beneath the surface, but soon coming above it. Its
compound sporophore, in the earliest stages observed by Hoffmann and myself, is a
small spherical body attached by one side to the substratum and the mycelium, and
consisting of closely interwoven hyphae with narrow interstices which in part contain
air. In quite small specimens 1 mm. in diameter, a median vertical longitudinal
section shows a fibrillation radiating from the point of attachment, in older ones there
is no apparent arrangement in the weft. The surface has from the first the same close
felt of hairs as the mature peridium. Still older individuals show the chambers in
the interior of the gleba in the form of narrow, air-conducting, and very sinuous cavities ;
that part of the walls which adjoins the cavities contains no air and shows the structure
of the hymenial layer. The chambers themselves are filled at first with loosely woven
filaments which run from one wall to the wall opposite and gradually disappear.

These data prove that the parts are formed by the splitting and differentiation of
the originally uniform mass of tissue. The formation begins, as far as I could deter-
mine, in the periphery and advances in the direction of the base, where a portion
of the original tissue (the basal portion) remains unaltered. As the development
proceeds the folds in the walls of the chambers become more and more smoothed
out and the chambers are thus enlarged. The expansion of the cells of the trama
has no doubt much to do with this change. What is known of other Hymenogastreae
agrees essentially with the above account. There is nothing of general importance
to be added to the remarks which have been made in a previous page on the structure
of the mature plant, and the same may be said of the forms included in the group
of the Secotieae. As regards other forms which have been placed by authors with
Secotium, especially Berkeley’s remarkable Polyplocium, it must be left to further
investigations to determine whether they belong to this or to some other place.

2. Scleroderma and Lycoperdaceae. Specimens of Geaster hygrometricus of
the size of a pea consist of a uniform soft tissue containing air and formed of delicate
segmented hyphae; it is of a whitish colour in the inside and brown at the cir-
cumference, and is attached to a felted mycelium which often spreads in the soil
for the distance of an inch all round. Older specimens, which may be of the size
of a hazel-nut in strongly developed plants, show the fibrillose layer of the peridium
to be described below, in their periphery; in the interior the hyphae part from
one another to form the chambers of the gleba, into which the hymenial hyphae
shoot out; the layer of collenchyma, the description of which must also be deferred,
is not yet ‘present; I have never observed its formation. Here too the facts point

314 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

to a splitting and differentiation of an originally uniform hyphal weft, and the accounts
which we possess would seem to show that this may be assumed of the other genera.
It is true also of Scleroderma verrucosum, according to Sorokin’s recent observations,
except that the hymenial coil in each chamber of the gleba is formed, if that observer
is correct, by the branching of a single bypha which grows from the wall into
the chamber at a very early period of the development.

The ripening of the gleba begins in Geaster hygrometricus (Fig. 146) at the apex and
advances from thence towards the base. According to Bonorden’s and Tulasne’s
statements it begins in Lycoperdon and Scleroderma in the middle line and proceeds
centrifugally; according to Sorokin the points where the ripening commences in
Scleroderma verrucosum vary in different individuals, but are always situated inside the

leba.
és The fully formed cagz//itium consists in most of the forms first to be considered of a
countless number of single tubes or portions of hyphae, which are only woven, not grown,
together and can therefore be easily isolated without tearing. Form, size, and structure in
these capillitium-threads are different in different genera and species, and serve admirably
to distinguish the latter. The threads are generally unsegmented and unicellular ;

FG. 145. Isolated threads of the capillitium @ of Geaster coliformis, P.; 5 of Bovista plumbea, P.; c of Myce-
nastrum Corium, Desv. a magn. 190, 5 and c go times.

they are simple or very rarely branched and shortly fusiform tubes in Geaster coli-
formis (Fig. 145 2), elongate fusiform and usually unbranched and with the extremities
very finely tapering and the membrane thickened till the lumen disappears in G. for-
nicatus, G. fimbriatus, and G. mammosus, &c. In the species of Lycoperdon the
threads are elongated, curved, and sometimes torulose, and simple or divided into
single branches which are quite irregular in their disposition ; the extremities have long
acuminations or are closed by a broad transverse wall which indicates the point
of union of the thread with the previously formed delicate tramal hypha. Sometimes,
especially in L. Bovista and L. giganteum, they have a transverse septum here and
there, and their greatly thickened lateral walls are funished with pits, which is not
the case in the other genera. The threads in Bovista (Fig. 145 4) have no transverse
walls and have the appearance of a many-rayed star; a short thick primary stem,
which often shows plainly the former place of junction, sends out short branches in
several directions; the branches form on the average four bifurcations, which increase
in length but diminish in thickness with each successive order, those of the last order
being prolonged into tapering hairs. Mycenastrum (Fig. 145 ¢) has short thick

CHAPTER V.--COMPARATIVE REVIEW.—GASTROMFCETES. 315

unicellular threads with the primary stem fusiform and simple or divided into a
few branches and beset, especially at the extremities, with short pointed branches like
spikes.

Geaster hygrometricus is the only one of the species in question with which I
am acquainted in which the mature capillitium forms a connected net-work. The
much branched, often torulose and unusually thick-walled threads wind in and
out confusedly among one another, and their extremities are often swollen into a
head and adhere firmly together. Like the earlier observers I found no true capillitium
in Scleroderma, only the walls of the chambers dried up and disorganised. Sorokin
speaks otherwise on this point, but it is possible that he was not examining the same
species.

The Zeridium of Scleroderma is thick and leathery, but it has much the same fibrillose
structure as the Hymenogastreae described above.

In Lycoperdon, Bovista, Mycenastrum, Geaster, Sclerangium, &c. the wall
of the peridium is differentiated into two concentric separable layers, peridium interius
and exterius. The inner layer is usually a thin membrane of the consistence of paper,
but in Mycenastrum it is cork-like and more than two millimetres in thickness. In
Bovista, Geaster, and species of Lycoperdon, the latter of which require more
exact investigation, it consists of several layers of stout hyphae which run in the direc-
tion of the surface and are firmly intertwined, having generally the structure and appear-
ance of capillitium-threads. In Geaster hygrometricus the elements of the peridium are
exactly like those of the capillitium, and are continuous with them, and the capillitium-net
is therefore concrescent everywhere with the peridium. Inall the species of Lycoperdon
which have been examinedand in Geaster fimbriatusand G. fornicatus thehyphaeare distin-
guished from the capillitium-threads by their smallersize and clearer colour, but they send
countless branches into the interior of the peridium, which, as long as they are free, have
all the characters of capillitium-threads. The inner peridium of Bovista plumbea has a
similar structure and the same dense woolly covering on the inner surface formed of
threads which have their origin in the weft of the peridium ; but these do not resemble
the capillitium-threads, nor are they connected with them, but are long fine tapering un-
branched hyphae. The inner peridium of Mycenastrum Corium is a dense irregular air-
containing weft of hyphae with brown membranes, more finely fibrillose and denser
in the outer region than in the inner. The hyphae end on the inner surface in pointed
branches which resemble but are always more slender than the capillitium-threads.

We know from descriptions that the inner peridia of most forms, Geaster for
instance especially, ultimately open in a fixed manner at the apex and discharge
the spores. The anatomical conditions which lie at the bottom of the process
have not been thoroughly examined. Where the inner peridium passes into a central
column or a sterile basal portion of the gleba, these parts, so far as they have been
examined, are found to have essentially the structure of the trama. The stalk-like
projecting basal portion of Lycoperdon has chambers like the gleba, but the walls
of the chambers are sterile or furnished only with insignificant traces of basidia.

The outer peridium in Mycenastrum is a whitish soft thin membrane covering the inner
peridium and composed of a loose weft of colourless thin-walled cylindrical hyphae ;
when mature it peels off in lobes and at length leaves the inner peridium uncovered.
“The peridium externum is more highly developed in Lycoperdon and Bovista. In
these genera it is formed of large-celled usually pseudo-parenchymatous tissue, which
in some cases, as Bovista plumbea, is seen to consist of several layers and often has
external projections in the shape of warts, spikes, &c. In the young state it adheres
firmly to the inner peridium, the elements of the two passing into one another.
At maturity, when the copious excretion of water already described takes place in
the compound sporophore in forming the spores, the inner layer of the outer peridium
becomes disorganised and is changed into a slimy or fluid mass, which soon dries
up or is absorbed, and hence the outer peridium often peels off from the inner and

316 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

falls away (Vittadini). In some, perhaps in most species, as for instance in Bovista
plumbea and Lycoperdon perlatum, according to Tulasne and Vittadini, the dis-
organisation affects the whole of the outer peridium and it becomes changed into
a slimy mass, which turns as it dries into a brittle and almost structureless mem-
brane.

. The structure of the peridium is more complicated in Geaster. G. hygrometricus is
up to the period of perfect maturity a roundish body, which may be of the size of
a hazel-nut and remains beneath the surface of the ground (Fig. 146). Six layers
may be distinguished in the peridium in a vertical longitudinal section a short time
before the compound sporophore is mature. The outermost layer is of a brownish
colour, flaky and fibrous, and is continued on one side into the mycelial strands which
spread through the soil and on the other passes into the second layer; a thick stout
brown membrane entirely covering the compound sporophore. This is followed
towards the inside by'a white layer, which is more largely developed at the base of the
compound sporophore than elsewhere and is immediately continuous at that spot with
the inner peridium and the gleba. Both of these last-mentioned layers are formed of
stout closely-woven hyphae running in the direction of the surface, and may be combined
under the name of the 2rzllose layer. The inner of the two is lined on the inside by the
collenchyma-layer (Fig. 146 c), except where its basal portion passes into the gleba.
This layer is cartilaginously gelatinous and consists of hyphal branches of uniform
height connected together without interstices,
which are placed palisade-like vertically to the
surface and are bent as they spring from the
hyphae of the fibrillose layer. The strongly
thickened stratified walls of the cells of this layer
have great capacity for swelling. Inwards from
the collenchyma is a white layer, the innermost
region of which is the inner Zeridium, while
the outer, which inay be called the sfl/t-layer,
consists of soft loosely woven hyphae which
pass at many points into the inner peridium.
When the Fungus is quite matured, the outer

oe N \
RN 1 2
EN].

Fic. 146. Geaster hygrometricus. Vertical median
longitudinal section of a fully grown nearly mature
;pecii very slightly ified. c collench layer,
£ gleba, the apex of which is beginning to assume a dark
colour as the spores ripen.

peridium, through the influence of moisture and
through the swelling of the collenchyma-layer,
bursts outwards from the.apex in a stellate

manner, forming several lobes which turn back,

so that the upper surface which is covered by the collenchyma hecomes convex. The
split-layer is by this means so torn to pieces that its constituent parts remain hanging
as perishable flakes, some to the collenchyma, some to the inner peridium. It is known
‘that the collenchyma-layer retains its hygroscopic qualities a long time, and the outer
peridium remains a long time lying on the soil, stellate in shape, spreading out its
rays in moist weather and bending them inwards in dry. The flaky investment of
the outer peridium is often more strongly developed in Geaster fimbriatus and G.fornicatus
than in G. hygrometricus, and in G. fornicatus it is composed of the finest of hyphae ;
it tears away from the fibrillose layer when the peridium is ruptured and lies on the
ground beneath the peridium as an open empty sac. The extremities of the lobes
remain for the time firmly united to the margin of this sac, and as the collenchyma-
layer expands greatly, the star formed by it and the fibrillose layer, especially in
G. fornicatus, becomes convex upwards, and carries the inner peridium on the apex
of the convexity. The fibrillose layer is comparatively thinner in these and other
species than in G. hygrometricus and is not divided into two layers. The collenchyma-
layer consists of large-celled transparent pseudo-parenchyma, which swells up strongly
in water and causes the opening of the peridium and the convexity by its expansion,
whether this is due to swelling only, or perhaps to growth also. In G. fornicatus,

CHAPTER V.—COMPARATIVE REVIEW.—GASTROMYCETES, 317

G. fimbriatus, G. coliformis, and others its cells are delicate, and it becomes full of
fissures soon after the peridium has opened, and unable to assist in the bending
of the rays. In G. mammosus and, according to Tulasne, in G. rufescens on the
contrary it has the same persistent hygroscopic qualities as in G. hygrometricus.

3. The differences between the genera Batarrea and Podaxon and the typical
Lycoperdaceae which have been hitherto under consideration are sufficiently striking to
require a special description. The early stages of the development are not known in
either of them.

A half-ripe specimen of Batarrea Steveni from the south of Russia examined
by myself was in shape a cushion-like body (Fig 147 a) with a regularly convex
upper surface and a diameter of nearly seven centimetres. The vertical median
section shows a structure, which may be roughly compared with that of a nearly ripe
Geaster. An inner peridium shaped like the plano-convex blunt-edged pileus of an
Agaric with an average thickness of one centimetre incloses the almost ripe gleba,
which has a scleroderma-like structure, except that many of the stronger walls of
the chambers run vertically from the upper to the lower surface ; isolated capillitium-
threads occur amongst the spore-dust. The threads are short and obtusely fusiform

FIG. 147. Batarrea Steveni, Fr. Vertical median longitudinal

i aa young: i but with most of its spores already
ripe. 6a mature specimen (in the latter the apex only and base of the
stipe are depicted). # and % the outer, the inner peridium, g the

gleba; the lines in the gleba show the position of the stronger FIG. 148. Batarrea Steveni, Fr.
remains of the trama. One third the natural size, semi-diagrammati- Isolated threads of the capillitium,
cally represented. magn. 390 times.

and irregularly curved, and show at their extremities or on their sides evident traces of
their former attachment; the inner surface of their thin membrane, smooth on the
outer surface, has delicate brown spiral or annular thickenings, which Berkeley!
was the first to describe (Fig. 148). The outer peridium is a stout membrane
about 1 mm. in thickness, which lies everywhere close upon the upper surface
of the inner peridium; its lower portion is a massive cushion-like body more than
2 cm. thick in the middle. In later stages of the development an axile portion
of the basal cushion beneath the centre of the inner peridium developes ultimately
into an erect stipe which may be a foot in length and 1-1.5 cm. in thickness
with scales on its upper rough and fissured surface, and carries the inner peri-
dium up with it (Fig. 147 4). The apical portion of the outer peridium is torn
from the basal by the elongation of the stipe, and remains hanging in shreds
from the upper surface and margin of the inner peridium, while the basal portion

1 Hooker's Journ. II, 1843.

318 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

surrounds the lower extremity of the stipe like the volva of Amanita. Ultimately
the wall of the inner peridium parts by a circular fissure beneath the margin, the
upper piece falls away from the lower, which remains connected with the stipe, and
from the gleba, and the spores are dispersed as dust. The tissue of Batarrea Steveni
is entirely formed of stout hyphae with interstices which usually contain air; the
hyphae in the wall of the hollow stipe are vertical and parallel to one another, as is
the rule in most of the Hymenomycetes. There is no gelatinous tissue. In specimens
with the outer peridium still closed the stipe is indicated only by the denser structure
and darker colour of the tissue of the basal portion at the
spot where the stipe subsequently originates.

Queletia! of Fries seems to approach nearest to Batarrea,
and perhaps also to Tulostoma.

Podaxon has long-stalked ovoid or elongated peridia
more than an inch in thickness, with a lateral wall of the
thickness of a stout sheet of paper, which ultimately opens
by lobes or scales and has the stout fibrillose structure of
the stipe. The same structure is seen in the central column
which traverses the peridium to the apex as a prolongation
of the stipe. The space between the column and the wall
is filled in the ripe compound sporophore with a connected
capillitium, formed of long spiral tubes with a transverse wall
only here and there. These tubes shoot out in numbers
from the parallel peripheral hyphae of the central column,
and run in the young plant into the outer wall of the peri-
dium, which is torn away from them when the plant is
matured. They are but little branched, and are rarely
found with blind ends and these always on one side only.
They are held firmiy together and form a net-work after
maturity, being interlaced and wound round one another
in every direction. They have rather thin yellow walls in
Podaxon pistillaris and flatten into ribbons in the mature
and dry condition. Some of them behave in the same way
in P. carcinomatis, but others have thick yellowish brown
membranes, which often have fine spiral striations and
readily tear into spiral bands in the line of the striae, as

: _ Berkeley? has recorded. See Fig. 149. The spaces between

Fe Sie ora tabectthecpilitan the capillitium-threads are filled with spores and the dried
Sous a De a remains of the membranes of the basidia, which have become
times. more or less of a brown colour and partly adhere to the
threads. Specimens of Podaxon pistillaris or an allied species,

which were younger but had reached their full size*, showed the cavity of the peridium
filled with a gleba containing an extremely large number of narrow and very sinuous
chambers, very thin trama-plates, and a dense hymenial layer consisting entirely
of stout four-spored basidia, The capillitium-threads were already discernible as broad
but thin-walled hyphae passing on one side into the wall of the peridium, on the other
into the columella, and in the gleba running, as in Lycoperdon, partly in the trama-plates,
partly transversely through the chambers. If a statement of Corda * may be applied
to this plant, the early development of the stalked peridium described above takes
place inside a peridium externum which is subsequently broken through, just as in

1 K. Vet. Acad. Förhandl. &c. Stockholm, 1871, No. 2.

2 Hooker’s Journ. IV, p. 292.

® In the Herbarium at Berlin, marked Schweinfurth, Iter 2, No. 275.
* See Icon. VI, t. ITI, f. 44, and the text belonging to it.

CHAPTER V.—COMPARATIVE REVIEW.—GASTROMYCETES. 319

Batarrea. At any rate the Fungus described by Corda under the name of Cauloglossum
in the place cited is very near Podaxon, and must be placed with that genus among
the Lycoperdaceae. It is plain, from the remarks recently made above on the Secotieae,
that their arrangement in one special group along with Podaxon is founded only on
superficial resemblances and is not tenable, and that the group of Podaxineae as hitherto
constituted must be broken up.

4. The ripe compound sporophores of the larger Nidularieae were described by
earlier observers as delicate open cups about 1 cm. in diameter containing usually
10-20 lenticular seed-like bodies. The cup is now known as the peridium, and
the seed-like bodies as peridiola or sporangia; the latter should be called the
chambers of the gleba if our present terminology is strictly adhered to. The structure
and development of these Fungi have been investigated by J. Schmitz, Tulasne, Sachs,
Eidam, and Brefeld. Crucibulum vulgare, Tul. may be taken as an example of the
group, and the description of it will be founded in the main on the works of Sachs and

FIG. 150. Crucidulum vulgare. A—C median FIG. 151. Crucibulum vulgare. Thin median section through
longitudinal section through ripening sporophores ; suc- the upper part of a sporophore of about the same age as 3 in Fig.
cessive stages of development according to the letters. £50, more highly magnified and seen in transmitted light, the dark
D sporophore just ripe in which the epiphragm is be- parts containing air; a? outer, 2 inner layer of the wall of the peri-
ginning to disappear, seen from without. .4—C slightly dium, z/ and a/ its hairs, » funiculus, 2 the layer which forms a sheath
magnified, D natural size. round it and belongs to a peridiolum which is divided through the

middle. After Sachs.

Brefeld. The first beginnings of the compound sporophores are small spherical bodies
produced by the interweaving of copiously branched mycelial hyphae. The weft of
primordial hyphae thus formed is at first close and colourless and contains air ; but the
branches at the periphery soon develope into stout hairs with tooth-like branches and
brown membranes, which cover the surface as a brown felt. With this covering
the small sphere grows by constant formation of new elements in the interior of the
hyphal weft into a thick cylindrical or obconical body about 6 mm. in height. The
differentiation into the parts which are found at maturity begins before the body has
reached half its ultimate size and advances with the general growth. The first
separation is seen in the internal primordial tissue which is originally uniformly white in
consequence of the air contained in it, in other words in the opaque primordial tissue,
and the result is that a zone between the periphery and the middle becomes a gelatinous
felted tissue free from air and therefore transparent. The differentiation of this zone
begins above the base of the body; the zone itself, which follows the form of the
surface of the body, is concave upwards and thickest in the middle, thinning out

320 DIVISION I].—COURSE OF DEVELOPMENT OF FUNGI.

towards the upper end, where the margin at length reaches nearly to the apical surface
of the peridium (Fig. 150 A). By the formation of this gelatinous layer the dense
non-gelatinous tissue outside it is separated from the rest and becomes the lateral
wall of the peridium, which is then differentiated into two concentric layers, an outer
permanent layer of brown felt and an inner whitish layer. Meanwhile no separ-
ation takes place in the middle and beneath the apex, but the dense still undiffer-
entiated primitive tissue extends from the latter into the interior space as a thick round
sac. At length the differentiation spreads further into the interior of the originally
uniform mass, while all the parts increase simultaneously in volume. Portions
which are at first round in form become
more dense and are separated from one
another by the spread of the gelatinisation
from without inwards successively between
them (Figs. 150 B, 151). These are the
primordia of the chambers of the gleba
or feridiola. During their further inde-
pendent growth, the gelatinisation goes
on also beneath the apical surface, which
is now covered only by a thin continua-
tion of the inner wall of the peridium.
The apex is at first clothed with brown
hairs ; as it increases in size with the
general growth the hairs are pushed aside
and no new ones are formed; the summit
is therefore destitute of the covering of
hairs, and is a thin white membrane, the
epiphragm (Fig. 150 D), which becomes
torn up and disappears at maturity, The
gelatinous tissue round the peridiola also
disappears, and the latter lie heaped up
at the bottom of the now open cup-shaped
sporophore.

The peridiola grow from their first be-
ginnings into a lenticular form, and be-
come inclined obliquely at an acute angle
opening upwards to the lateral wall of the
peridium (Figs. 150 C, 152). A central
cavity appears in them at an early period,
filled at first, it is said, by a felted gela-
tinous tissue which afterwards disappears,
but this perhaps is uncertain ; the cavity

FIG. 152. Crucibulum vulgare, Thin median section through has the same shape as the peridiolum, and
a sporophore like that in Fig. 151, more highly magnified. Two peri- a . F
diola with their funiculi are cut through the middle; a third Iying COntinues relatively small, and is densely
between them is cut through on the outside only. Meaningofthe Filled at the time of maturity with some-

what long spores. Two to four spores are

formed on each of the basidia, which, with
the paraphyses, form a dense hymenial layer lining the cavity. The constituents of
the hymenial layer become thick-walled after they have produced the spores and form
a stout palisade layer round the cavity, and this is again invested by the still harder
thick outer wall of the peridiole, into the structure of which we must not enter further
in this place.

From the accounts which we possess it seems certain that the course of the develop-
ment of the compound sporophore is similar in the genera Cyathus and Nidularia
to that here described in the case of Crucibulum, the only exception being that in

CHAPTER V.—COMPARATIVE REVIEW.—GASTROMYCETES. 321

Nidularia the shape’ and opening of the peridium is less regular. As regards
Nidularia there is nothing to be added to what has been already said. It may be
specially noticed that the surface of the peridiola has the same structure in all cases,
at least in the stages of the development which have been examined. The earliest
states are not known, but peculiar appendages are found on the surface of the mature
peridiola of Crucibulum and Cyathus ; these appendages are produced, like the other
parts, from the primitive tissue by the process of differentiation and are not subjected
to gelatinisation ; but the history of their development is not yet clearly understood,
and some parts of it are matters of controversy (Figs. 150 C, 151%, /, 152). The mature
peridiolum of Crucibulum has an umbilical depression in the middle of the surface which
is towards the peridium, and in the depression is a body which in the intact state is
smooth and round and projects towards the outside. This body consists of a compact
strand of very slender hyphae rolled up and bent into a dense coil, which may therefore
be termed the umbilical coil or tuft. The hyphae are surrounded by a colourless
mucilage ; and this mucilage and the whole tuft swell when moistened and the hyphae
become soft, so that they may be easily drawn out into a filiform strand 3-4 centi-
metres in length. The hyphae of the tuft are inserted at one end in the outer layer
of the wall of the peridiolum, and where they are most perfect they continue their
course closely united and parallel to one another as a smooth and somewhat sinuous
strand visible to the naked eye as a fine thread, the fumzculus, which is attached to
the inner surface of the wall of the peridium. In the young state, before the
differentiation, both strand and coil are loosely enveloped in a layer of hyphae which
passes through the gelatinous felt like a bag stretched in the direction of the funiculus.
As the development is completed the bag becomes gelatinised, but remains of it are
still to be seen as a thin covering especially over the coil. The existence of the
funiculus is denied in the case of Crucibulum by Brefeld as against Tulasne and
Sachs ; but it is certainly often there. It is true that I have been myself unable to
find a funiculus in some peridioles, but the coil always showed a small point which
answers to it; it would appear therefore that in such cases it has itself finally suffered
gelatinisation.

In Cyathus under otherwise similar conditions coil and strand and bag are persistent,
and thus more complicated phenomena arise, which vary in particular points according
to the species.

In Cyathus striatus, for example, the funiculus when intact has an average length of
more than 2mm. _ It is nearly cylindrical in shape, and is divided by a deep transverse
constriction in the middle into an upper and a lower portion. The lower portion and
the slender middle piece are formed of a weft of much-branched and thick-walled but
slender hyphae; this weft in the dry state is brittle, but when moist is tough and
tenacious and may be stretched to more than double its length. The upper portion
is a bag which reaches from the lower portion to the wall of the peridiolum and passes
into it; in this bag is a filiform strand of slender parallel hyphae about 3 cm. long
and disposed therefore in numerous coils inside the bag, which is only I mm. in
length. The upper end of the strand is attached to the peridiolum, the lower passes
into a coil, which, like the umbilical coil of Crucibulum, is enveloped in mucilage and
enclosed in the somewhat swollen lower end of the bag. The wall of the bag has
essentially the same structure as the lower portion of the funiculus. The whole body
is rather brittle in the dry state. It swells by absorption of water and becomes soft
and flexible ; the coiled strand may be drawn out to the length mentioned above when
the bag is torn up, but not much beyond it; the coil behaves exactly as in Crucibulum ;
by a little manipulation its hyphae may be drawn out together till the whole strand
reaches to a length of 8cm. The hyphae of the extensible tissue of the funiculi are
slender and usually have their walls thickened till the lumina disappear; they are
divided into long cells resting one on another with their swollen extremities, where
they show peculiar clamp-formations.

[4] Y

322 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

It is probable, as Brefeld suggests, that these coils and funiculi, thus provided with
slimy mucilage and capable of being drawn out into strands, are contrivances for the
dissemination of the peridiola by animals and for furthering the germination of the
spores. That there is no spontaneous dehiscence of the peridiola is in favour of this
view, but the course of the events which would in that case come under consideration
is not yet known.

(5) The development of the compound sporophores of the Phalloideae has been
studied exactly in Phallus (P.impudicus and P. caninus) and Clathrus. They first appear
in Phallus (Fig. 153) as ellipsoid swellings about ı mm. high on the mycelial strands,
and consist at first of a uniform compact weft containing air and formed of very
delicate (primordial) hyphae. In specimens of larger growth (Fig. 153 z, v) this is
differentiated into a dome-shaped central column rising vertically from the point of
insertion, a bell-shaped layer of felted gelatinous tissue enveloping the column,
gelatinous layer, and a white membrane, outer wall of the peridium, which sur-
rounds the gelatinous layer and passes at the point of insertion into the central
column. The two last named parts consist of primordial tissue.. While the whole
sporophore as it increases in size becomes more narrowly ovoid in form, and the outer
wall and the gelatinous layer grow in circumference and thickness, though their
structure remains the same, the central column acquires the form of a globular head
supported on a cylindrical stipe. Its primordial tissue at first homogeneous is at the
same time differentiated into the gleda, the receptaculum of the gleba, which is peculiar
to the Phalloideae, and in the present case is a simple fusiform s/zde, and a white
membrane surrounding the other two parts (Fig. 153 w, x). This membrane forms
the zznermost layer of the wall of the peridium, which consists therefore of three
concentric layers, the outer and inner white membranes which unite at the base, and
the much broader gelatinous layer lying between the two. The gleba lies in the upper
capitate portion of the central column in the form of a thick horizontal ring, which is
semicircular on the transverse section and is surrounded on the outside by the inner
wall of the peridium, while its inner surface rests on a conical axile portion of the
central column. This portion, which may be briefly termed the cone, passes through
the whole of the gleba up to the summit of the column. The structure of the gleba is
the same as in the Hymenogastreae and Lycoperdäceae but without coils; its chambers
are very numerous and narrow, and the trama when somewhat advanced in its
development consists of soft gelatinous tissue with laminae which spring on one
side from the inner wall of the peridium, on the other from the cone. The outer-
most zone of the cone bordering on the gleba separates early in Phallus impudicus
from the inner tissue, forming a distinct layer, and becoming ultimately the free conical
‘pileus ’ which carries the gleba. In Ph. caninus this separation does not take place.
The stipe is at first a very narrowly, afterwards a more broadly fusiform body which
runs through the longitudinal axis of the entire central column from its apex to its
base. In its earliest condition it is a transparent band and is distinguished from the
white primordial tissue, which contains air, solely by the absence of air from its
interstices. As growth proceeds, the uniform hyphal tissue becomes differentiated
into an axile tissue-strand and a peripheral layer, the wall of the stipe. The latter
consists of laminae of a round-celled pseudo-parenchyma, which unite together, like
those of the gleba, to form one layer (Ph. caninus) or several layers (Ph. impudicus)
of closed chambers. The chambers are large, but so much compressed from above
downwards, that the breadth of their interior space is scarcely equal to the thickness
of their walls; the walls themselves are much twisted and folded. The chambers
are filled with a soft gelatinous felt and the axile strand of the stipe is formed of a
like felt. The wall-of the stipe at its upper extremity has only deep pit-like folds
in its surface, no chambers being formed in the interior. The stipe when once formed
increases greatly in size, the parenchyma of its wall enlarging by simple expansion
of its cells from the moment that it is distinctly differentiated. The growth of the

CHAPTER V.—COMPARATIVE REVIEW.—GASTROMYCETES. 323

two outer layers and of the inner wall of the peridium, so far as it surrounds the gleba,
advances farz fassu with the enlargement of the stipe. On the other hand, the tissue
in the cone and in the portion of the central column beneath the gleba diminishes
in proportion as the stipe enlarges, till at length in Ph. caninus (Fig. 153 y) it is only
a thin white membrane; in Ph. impudicus it remains of larger size underneath the
gleba, forming a cup-shaped basal piece which supports the lower extremity of the
stipe (Fig. 154) ; in the cone it stretches into a thin white membrane, as in the other
species. The gleba, in which the formation of spores is completed or nearly completed
during the expansion of the stipe, dilates in Ph. caninus into a thin conical cap
covering the upper part of the stipe close beneath the extreme summit; in Ph. impudicus
it diminishes less in thickness in proportion to the extension of its surface, and the
hyphae of the trama even manifest an active growth by the expansion of their cells.
No change in structure worth mentioning here occurs in the parts surrounding the
stipe during the time that it is enlarging beyond an evident increase in the size of the
hyphae. The cells of the parenchyma of the stipe itself continue thin-walled and

|

FIG. 154. Phallus impudicus. A nearly mature

FIG. 153. Phallus caninus. Young sporophore partly attached example before the elongation of the stipe, in median
to the mycelium 7 in median longitudinal section and natural size. longitudinal section ; 2 mycelium, a outer, z inner
Succession of stages of development according to the letters u—y. wall, g gelatinous layer of the peridium, s¢ stipe, %
y a specimen not fully grown but with ripe spores ; @ the outer wall, its cavity filled with mucilage, ¢ lower margin of the
“the inner wall, g the gelatinous layer of the peridium, 2 the basal pileus, sp gleba, » the cup-shaped basal portion,
portion, & the cone, s the stipe, rd the gleba. x the spot where the peridium is ruptured by the

elongation of the stipe. After Sachs, Two-thirds of
natural size.

filled with a watery fluid. At length all growth by expansion of cells already formed
or by the formation of new ones comes to an end in all parts, and then comes a sudden
increase in the length of the stipe, which thrusts the gleba which is attached to its
summit against the apex of the peridium and bursting through it raises the gleba
high above it. The elongation is brought about simply by the raising and smoothing
out of the folds in the plates of parenchyma in the wall of the stipe, like the folds in
a paper hand-lantern, to repeat the comparison of the old botanist Schäffer, till
the length of the chambers is at least equal to the breadth; the elongation of the
chambers is caused by accumulation of air within them and their consequent inflation.
The gelatinous felt which fills them at first is torn up and disappears, and the axile
gelatinous strand is also torn and replaced by air. This process takes place simul-
taneously at all points in Ph. impudicus; in Ph. caninus it begins above and advances
slowly towards the base. The elongation of the stipe causes the inner peridium
of Ph. caninus to separate into two parts by an annular fissure beneath the gleba;
the upper portion with the remains of the cone is carried upwards while the lower
Y 2

324 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

continues attached round the base of the stipe. In Ph. impudicus the inner wall of
the peridium is also rent at its apex, and the gleba is detached from it and rises
clear above it. An annular transverse rent in the lower portion of the cone separates
the cup-shaped basal portion which remains round the base of the stipe from the upper
portion, which is torn into shreds, and the pileus which bears the gleba is thus
separated from the stipe except at its upper margin which adheres firmly to the
summit of the stipe.

The gleba when exposed to the air drops from its stalk as a slimy mass containing
the spores in consequence of the deliquescence of its gelatinous tissue. In Phallus
caninus the cone and the part of the inner wall of the peridium which covers the
gleba go through this process of disorganisation and become indistinguishable before
deliquescence. For further particulars and differences among the species the reader is
referred to the more elaborate works which will be cited below, and the descriptions in

systematic treatises.

FIG. 155. Clathrus cancellatus. Young
compound sporophore in median longitudinal,
section. #2 mycelium, 7, 7sections through the
strands of the receptaculum, surrounding the

leba, which is shaded. Further explanation a a a
= the text: : The Reine ts dliscrammatie FIG, 156. Clathrus cancellatus, Mature specimen ;
after Tulasne's and Berkeley’s drawings. ii wath paratively narrow fissures has
Natural size, issued from the ruptured peridium, Sketched from a photo-

graph by Bornet. Half the natural size.

Clathrus cancellatus, as we have known since Micheli’s time, agrees with Phallus in
the character of the gleba and peridium. But the receptaculum which raises the
gleba from out of the peridium has the form of a net or lattice-work with large
meshes surrounding the outer surface of the gleba. We know from Tulasne' especially
that the development of the parts begins here, as in Phallus, with a separation
of the uniform tissue of the young compound sporophore into central column,
gelatinous layer, and outer wall of the peridium (Fig. 155). Lamelliform processes
which anastomose and form a net-work pass from the peridium to the surface of
the central column, passing like septa through the gelatinous layer. The lowest of
these converge towards the point of insertion of the column or of the whole body
and unite there. Then the column becomes further differentiated into the inner
wall of the peridium, the gleba, and a roundish axile gelatinous body of a cartilaginous
consistence. The latter occupies the entire central portion; its base rests on the
peridium and passes into it, the whole of its surface, with the exception of the point
of insertion, being covered by the thick gleba. The lamellae of the trama in the
gleba spring on all sides from the central body; hence it appears in a transverse

* Explor. sc. d’Algerie.

CHAPTER V.—COMPARATIVE REVIEW.—GASTROMYCETES. 325

section to be furnished at the circumference with numerous unequal processes and
projecting points radiating into the gleba. In the net-work of stripes, where the
septa from the outer wall touch on the inner wall, the white (primordial?) tissue
of the latter is more largely developed than in the interspaces. It is in the region
of these stripes that the receptaculum originates after the first formation of the
gleba. When the compound sporophore is mature the receptaculum expands greatly,
and while it remains attached at the point of insertion it rises far above the ruptured
peridium (Fig. 156). The gleba meanwhile, with its gelatinous support which is separated
from the point of insertion, is attached to the uppermost part of its inner surface; the
whole of the gelatinous tissue soon deliquesces, as in Phallus, into a slime which
drops off with the spores. The structure of the perfect receptaculum, as appears
especially from Corda’s accounts, is so like that of the same organ in Phallus, that
we can hardly doubt that the development of the tissues and the mechanism for
expansion are the same in both genera, though we cannot appeal to direct observations.

We are acquainted with a considerable number of very varied and sometimes strange
forms in the group of the Phalloideae, but most of these have been examined only
in single mature specimens. A large collection of them are found in Corda’.
All that is known of them, as regards the shape and structure of the peridium, gleba,
and spores, and especially the structure of the receptaculum, agrees in the main points
so fully with the descriptions here given of Phallus and Clathrus, that there can
be no doubt that the development is alike in all. This view is confirmed by Tulasne’s
researches into the young compound sporophores of Colus hirudinosus and by Corda’s
account of Tleodictyon.

The species chiefly differ from one another in the shape of the receptaculum, which,
as in Phallus and Clathrus, always emerges from the walls of the peridium. Some
are more like Phallus in this respect, others more like Clathrus ; others again depart
considerably from the type of both, as for example Aseroe, which has a star borne
on a thick erect stipe with dichotomous rays which are either expanded horizontally or
rise obliquely upwards, and has the gleba placed originally in the focus of the rays
above the stipe. From the material in our possession, imperfect as it is owing
to the rarity or perishable nature of most extra-European species, we may arrange
the majority at least of the forms in a gently graduated series according to their
affinities, with Clathrus (Fig. 156) at one end and Phallus (Fig. 153), Lysurus and
similar forms at the other. Fries? has already drawn attention to this connection.
Colus hirudinosus (Fig. 157) agrees very nearly with Clathrus cancellatus in its
development. But while in the latter the base of the receptaculum consists only
of a few short stripes which converge into a network and are connected at the extreme
base, it is developed in Colus into a hollow stipe, open above and below, in form
cylindrical-conical and nearly a third of the entire length of the whole sporophore.
The stipe divides above into from six to eight riband-like arms, which ascend
like the meridians of longitude on a globe and unite their upper extremities into
a small terminal plate which is pierced with holes like a coarse sieve. Alto-
gether therefore it forms a net-work, and the position of the gleba in it is the
same as in Clathrus, only the shape of the net is different and much more regular.
If the meridian arms were set free, and did not end in the plate above, we should
have the same plan as in Aseroe (Fig. 158) and in Calathiscus with some modi-
fication, where the gleba is borne on the extremity of the stipe, which is split up into
diverging arms.

Lastly, Aserophallus® (Fig. 159) has a comparatively long stipe, which divides
beneath the round gleba at its apex into four short arms which embrace it. Here
is at once a very near approach to the shape of Phallus, especially if we frame an idea

1 Icones, V, VI. ? Summa veget. Scand. 434.
3 Montagne et Leprieur in Ann. d. sc. nat. ser. 3, IV (1844).

326 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

for ourselves of the only possible form of the parts when enclosed in the peridium.
The cavity of the stipe is in this case also opened wide between the lobes; the
somewhat more persistent outer layer of the gleba with its thin walls makes no
difference in this respect. To arrive at the form of Phallus caninus or Simblum,
we must have the stipe closed at the apex and projecting in a conical shape into
the gleba, and the lobes must entirely disappear. We are not at present acquainted
with any intermediate forms. But if none are found, we have sufficient material to
show the family connection. Other genera than those already named are not taken
into the comparison, because they are not clearly known or because it is unnecessary
to adduce them. The reader is referred for them to the works which describe this
group. ‘
Phallus and its nearest allies are the members of the series of the Phalloideae which
depart farthest from the rest of the Gastromycetes. Clathrus is a link of connection
between them and the Gastromycetes through the Lycoperdaceae. To see this we
have only to compare its compound sporophores when ripening but still closed with
those of Geaster, and the collenchyma-layer of most species of this genus, at any
rate that of G. hygrometricus, with the receptaculum of Clathrus, The relation is

FiG. 157. Colus hirudtnosus. FIG. 158. Aseroe rubra, Sketch of a mature recep- FIG. 159. Aseroßhallus.
Sketch of a mature isolated recep- taculum which has issued from the peridium attached to it A ripe compound sporophore.
taculum which has issued from the below, and bears the gleba in the middle of the radiati After M and Le-
peridium. The black gleba hangs expansion. After Berkeley in Hooker's Journ. III, prieur, |. c., in note on p. 325.
down under the sieve-like terminal Tab. V. Half the natural size. Natural size.

plate. After Tulasne in Explor.
Scientif. d’Algerie. Twice the natural
size.

brought out very clearly by the circumstance that there are individuals of C.
eancellatus, in which the bars of the lattice-work, even in the ripe compound sporo-
phore, are excessively broad and the interstices only narrow slits ; here therefore the
receptaculum is a hollow body only slightly perforated.

The connection between Clathrus and Geaster appears to me to be still more com-
pletely established by the genus Mitremyces, which is chiefly American and still far
from being thoroughly known. But I do not attempt to describe it here, for I have
no sufficient account before me of the history of its development}. ,

6. A description of the genera Tulostoma, Poiysaccum, and Sphaerobolus may
be given here by way of appendix, because they depart in a remarkable manner
from the type of the groups which we have just been considering. But no special
proof is required to show that they approach very near to them and especially to
the Lycoperdaceae, and in this position may be regarded as the representatives of
distinct and at present small divisions which have to be co-ordinated with the others.

1 For the facts as at present known, see E. Fischer in Bot. Ztg. 1884.

CHAPTER V.—COMPARATIVE REVIEW.—GASTROMYCETES. 327

The peridia of Tulostoma are formed, according to Schröter, on subterranean
mycelial strands, which are flat sclerotia and may be 6 mm. in breadth; they are
probably shoots from these sclerotia, and are round bodies about 4mm. in diameter
composed of a uniform weft of primordial hyphae; the superficial ramifications
of the hyphae form a floccose envelope which attaches itself to the grains of sand
in the surrounding soil. The differentiation into gleba and peridium may be ob-
served when the compound sporophore has reached the size of 6-8 mm. The peridium
is a relatively thick hyphal layer entirely surrounding the gleba and having a conical
thickening at the upper end as the primordium of the papilla which afterwards
appears at the opening of the peridium; there is also a broadly obconical thickening
below. The peridium separates further into an axile cylinder situated beneath the
middle of the gleba and into a part which surrounds the cylinder like a sheath. The
cylinder elongates at maturity into the cylindrical stipe which attains a length of 3-6 cm.
and raises the peridium above the ground; the elongation causes the sheath to
separate by a transverse fissure into a lower portion, the base of the stipe, and an
upper, which surrounds the upper end of the stipe, according to Vittadini (see Fig. 160),
and both portions then dry up. There is no separation into inner and outer wall
in the peridium. The gleba is at first a reniform body which afterwards becomes
spherical in form, and is distinguished by the absence of chambers. It is formed
of a uniform tangled mass of hyphae about
2 in thickness, the branches of which pro-
duce the strangely-shaped basidia described
above on page 309. The abscision of the
spores is over and the basidia deliquesce
before the stipe begins to enlarge ; then the
spore-membranes turn brown, the - process
advancing, according to Schröter, from the
centre towards the circumference of the gleba.
A large number of the hyphae of the gleba
begin to develope shortly before the disap-
pearance of the basidia into the close net-work
of stout threads, which form the capillitium Gute 1 20 tere A 4
and grow all over the wall of the peridium, as stipe, the gleba at the apex beginning to assume the
in Geaster hygrometricus. ne Avene Manes En

Polysaccum is another strange object and
deserves further examination; it is a large
somewhat elongated or club-shaped body which has chambers throughout except
in the thin outermost fibrillose layer; a few concentric layers of chambers in the
periphery are smaller and sterile and together represent a peridium; the chambers
in the interior which are polyhedric, and may be as large as a pea at maturity,
are about I mm. in diameter when the spores begin to be formed, and are filled
with hyphae closely woven together into a hymenial coil and either sterile or pro-
ducing basidia. These hyphae have very soft gelatinous membranes, and the whole
coil may be removed uninjured from the brown trama. The chambers at maturity
contain only a chocolate-brown spore-powder, the tramal laminae with the peridium
being disorganised and desiccated and crumbling to pieces. No capillitium is formed.
The formation of the chambers begins at the apex and advances, very slowly as it
would appear, towards the base of the peridium which is sunk deep in the sandy
soil. Specimens are found in which the upper half is quite ripe while in the lower
all stages of the development may appear in unbroken succession one above another.
The earlier states are not known. The same thing appears to occur in Berkeley’s
Phellorinia. The agreement with Scleroderma is evident; it is possible that Poly-
saccum, Phellorinia, Scleroderma, and Melanogaster form a distinct group marked by
the hymenial coil which fills the chambers.

328 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

The mature peridium of Sphaerobolus stellatus is white and about as large as a
grain of mustard-seed, and is found either on the surface of the substratum, which
is usually decaying wood, or sunk in it. Its differentiation may be compared with
that of Geaster. A thick outer wall encloses a spherical peridium internum about
1 mm. in diameter, which in this genus is also termed a sporangium, and at maturity
consists to a great extent, and even in its outer surface, of a tenacious mucilage,
in which numerous basidiospores and other cells accompanying them are imbedded.
When young it contains a gleba formed of delicate hyphae surrounded by a thin hyphal
weft next the outer peridium, and imperfectly and irregularly divided into chambers
by narrow tramal lamellae containing air. The chambers are filled with hyphal
branches closely woven together and bearing basidia, which usually produce from
five to seven spores each. Ultimately the hyphae in the compound sporophore are
to a great extent disorganised and form the tenacious sticky mucilage mentioned above,
which has been carefully studied by E. Fischer. The ripe spores are retained in
the mucilage, and with them, especially in the periphery, isolated one-celled or few-
celled pieces of the trama or the basidia-bearing hyphae. Some of these pieces become
vesicular mucilage-cells several times larger than the basidiospores, and are incapable
of further development, but in their turn suffer disorganisation ; others become spores
or gemmae of a different kind, which are originally short cylindrical thin-walled
cells rich in protoplasm occurring singly or a few together in a row, different in
shape from the basidiospores and germinating very readily. They will be noticed
again on page 330. The outer wall is composed of two chief concentric layers; a
peripheral, white and floccose on the outer surface, which is again divided into two layers,
and an inner layer. The latter separates again into two layers, a peripheral dense fibril-
lose layer next within the outer layer, and a collenchyma-layer -united to the fibrillose
layer, and consisting chiefly of relatively large cells placed radially to the whole sphere in
the manner of a palisade. The whole of the outer wall when fully mature bursts at the
apex into 6-7 lobes in a stellate manner, and the inner peridium which is filled with
spores is not at first moved from its place. The rupture is caused by the greater
superficial extension of the collenchyma layer. Growth continues in this layer in
the direction of the surface after the rupture of the peridium, and as the other layers
do not grow with it, it is in a state of positive tension. Ultimately it breaks loose
with the fibrillose layer which adheres firmly to it from the peripheral layer, continuing
united to the latter only at the tips of the lobes, and carries the inner peridium on
its centre, which.is arched strongly outwards. If these processes are made to go
on slowly, the peridium remains attached though slightly to the collenchyma-layer,
as in Geaster fornicatus. Usually and normally the positive tension reaches a high
degree before the separation, which occurs suddenly in consequence of fluctuation
in the turgescence, the collenchyma-layer becomes convex outwards with a jerk
and a crackling sound, and the inner peridium which is only loosely attached is flung
away, in favourable cases to a distance of more than a millimetre, and adheres to any
object on which it alights.

The development of the structural conditions which are at the bottom of these
processes, the details of which are to be found in Pitra and E. Fischer, is the result of
the differentiation of a coil of hyphae originating in the branching of the mycelium and
at first perfectly uniform.

COURSE OF DEVELOPMENT AND AFFINITIES OF THE BasIDIOMYCETES,

Section XCI. The whole course of the development of a Basidiomycete
was first followed by Woronin in 1867, when he examined the genus Exobasidium,
a parasite on living species of Vaccinium. This very simple form consists in the
mature state of a basidial layer, which comes to the surface of the epidermis of the

CHAPTER V.—COMPARATIVE REVIEW.—-BASIDIOMYCETES. 329

host, and a mycelium which spreads widely in the part of the plant which it attacks,
deforming it more or less, and producing the basidial layer directly from its hyphae.
The basidia are as usual club-shaped, and abjoint four fusiform spores. The spores
divide as soon as they are ripe by transverse walls into four cells, and the two end-
cells germinate at the expense of the protoplasm of the other two as soon as they
reach a moist surface. If this is the surface of a young foliage-leaf of Vaccinium,
the germination consists in the putting out of a tube, which at once grows through
the young epidermis into the inner tissue of the leaf and there developes a mycelium.
The mycelium forms the hymenium which bears the basidia directly; the time
required in plants cultivated artificially is about 14 days from the sowing of the spores.
If the spores germinate on some other substratum not so favourable as the leaf of
Vaccinium, the germ-tube after attaining a short length begins to sprout and pro-
duces rather elongated fusiform sprout-cells which sprout only at their extremities.
The formation of sprouts may be repeated many times. Brefeld saw it continue for
a year in specimens cultivated in nutrient solutions, and the power of production
appeared to be unlimited. It can scarcely be doubted that the sprout-cells can give
rise to a mycelium like that of the primary spores in suitable substratum ; but this has
never been actually ascertained.

The development of the Tremellineae, the species of Dacryomyces for example
especially, would appear from the investigations which have been made to be the same
as in Exobasidium. I refer partly to the statements of Brefeld!, partly to an
unpublished series of researches conducted by Klebs. A mycelium is developed from
the germinating basidiospore under suitable conditions of nutrition, and the branches
from the mycelium combine to form compound sporophores which produce new
basidia. Under different conditions, not in all cases exactly defined, the germ-tubes
which proceed from the spores remain short and abjoint (successively ?) small secondary
spores or develope by sprouting. We shall return to these phenomena in a subsequent
page. There is moreover a further point’ of agreement between Dacryomyces and
Exobasidium; the ripe basidiospore at the time of abjunction divides by transverse
walls into short disc-like cells, daughter-spores, which are usually four in number,
but each of these is capable of germination in Dacryomyces in one of the forms
stated above. In other Tremellineae the basidiospores do not divide or they divide
in a different and peculiar form. \

We are acquainted with the whole of the life-history of the Hymenomycetes
proper in Typhula and species of Coprinus through the researches of Brefeld; in
Agaricus melleus through those of R. Hartig and Brefeld; in Crucibulum and Cyathus,
genera of the Nidularieae, from the labours of Eidam and Brefeld, and in Sphaerobolus
from those of E. Fischer.

The germinating spore of Agaricus melleus and Coprinus stercorarius puts
out a germ-tube, which in all the Coprini is swollen into a vesicle at its point of origin ;
the germ-tube developes directly into a mycelium and the compound sporophores are
formed directly on the mycelium from the ramifications of the hyphae. No organs
beside those described in the preceding pages, which can even be supposed to have
any connection with the propagation of the plant, nor any rudiments of them, have

” Hefepilze, p. 198.

330 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

ever been found. Every piece of the mycelium, in Coprinus every bit even of
a mutilated sporophore, may under conditions favourable to growth form the hyphal
branches which become a sporophore. The filiform mycelia, the sclerotia which may
be produced on them, and the strands of Agaricus melleus (see page 23) behave
alike in these respects.

In the rest of the Coprini which have been examined and in Typhula also the
mode of development is the same as in the above species, but a complication occurs
in them more or less frequently, which will be considered presently.

In Crucibulum again and Cyathus the course of events is entirely the same
as that in the Hymenomycetes above mentioned. In the proper nutrient solutions,
especially decoctions of dung, and a not too low temperature (15°-18° C., according to
Eidam 25° c.), the basidiospores put out germ-tubes, which under favourable conditions
develope directly into a mycelium, and its branches form the coils of primordial
hyphae which develope into peridia without the interposition of any intermediate
mem bers.

The history of Sphaerobolus is very peculiar according to E. Fischer’s account
of that plant. It was stated on page 328 that the sporangium or peridium when
flung off has the basidiospores mixed with the mucilage-cells and the gemmae.
These are all so firmly held together by the tenacious mucilage, that it is very
difficult to isolate them, and a spontaneous separation of the several elements has
never been observed, and from what we know is scarcely conceivable. If a sporan-
gium is flung to a spot where there is no moisture it dries up into a firm hard body,
which retains its vitality for months and swells when moistened, and then exhibits the
same phenomena of germination as a recently ejected specimen. But if a sporangium
falls at once on a moist substance, it puts out numerous germ-tubes from its entire
surface, so that it may be densely covered in a day or two with white hyphae
radiating in every direction. On a substratum which supplies sufficient nourishment
these develope without interruption into a’ mycelium which produces new peridia in
a few weeks or months without the aid of any other organs of reproduction.

It may be said therefore that the whole sporangium thus remaining in connection
produces by germination the commencement of a mycelium of many hyphae, and
that hardly any other mode of germination could occur in the natural course of
development, though it is easy to show that portions of the sporangium artificially
separated and even individual cells, if naturally capable of germination, may be made
to germinate when isolated in water or a nutrient solution.

A closer examination of the incidents in the entire sporangium disclose§ however
the curious fact, that the germ-tubes which spring from the surface and develope into
a mycelium proceed, as far as can be observed, from the gemmae and x0/ from the
basidiospores. As the germination of the whole body proceeds the basidiospores
lose their protoplasm and their membranes become more delicate and paler, and are
pierced with holes in places, and they themselves at length entirely disappear; the
products of their disorganisation are evidently employed with the mucilage which
envelopes them as food for the germ-tubes. Isolated gemmae germinate quickly
and readily in water, and normal mycelium is obtained from their germ-tubes, if proper
nutriment is supplied. Isolated basidiospores rarely produced germ-tubes in Fischer’s
experiments ; as a rule they did not germinate; and in the normal germination of

CHAPTER V.—COMPARATIVE REVIEW.—-BASIDIOMYCETES, 331

sporangia no germinating spore was observed among the multitude of gemmae with
their germ-tubes, only the successive disorganisation of the spores.

Section XCII. If putting Sphaerobolus on one side we consider the course of
development in the Basidiomycetes which have been described above and which have
been carefully examined, we find that in the simplest case, which is sometimes the one
exclusively observed, the germinating basidiospore gives rise directly to a mycelium,
the branches of which become sporophores producing basidia without the interposition
of any special intermediate members at all comparable with archicarps.

The circumstances which, as was intimated above, may produce complications
in this scheme are of the following kind. In describing the germination of the
basidiospores of Exobasidium and Dacryomyces in pages 328 and 329, it was stated
that the spore can under certain circumstances produce a great abundance of sprouts,
or may abjoint small cells acrogenously from short germ-tubes. These small cells
are round in Dacryomyces and about 2 » long, and in nutrient solutions they give rise
to germ-tubes, which may develope into filamentous and often large mycelia. These
mycelial hyphae and those also which proceed from basidiospores may abjoint small
cells in crowded tufts, which differ from the first in being ellipsoidal or rod-like in form,
but agree with them in giving rise to a mycelium with similar products. We learn
from Brefeld especially that similar phenomena have been observed in many
Tremellineae in forms which vary according to the species. The mycelium from
which these cells are abjointed may then produce the basidia-bearing compound
sporophores of Dacryomyces. The cells in question are, according to this description,
spores, but we may also call them by analogy gonzdia, if we wish to maintain the
traditional use of the word spore for basidiogenetic cells.

Gonidia in the same sense of the word and with essentially the same characters
occur also in some Tremellineae on the sporophores which produce basidia; such are
the cells capable of germination in form like a bent rod which are abjointed at the slender
extremities of hyphae in depressions with thickened and rounded margins in the
compound sporophores of Tremella Cerasi, Tul. The small round ‘cells also 2 » in
diameter, which according to Tulasne are abjointed like small heads on the extremities
of much branched hyphae in the hymenial layer of Tremella mesenterica, may be of the
same kind, though their germination has not yet been observed. Another form of goni-
dium, distinguished by the name of gemma and produced no doubt by external causes
which have yet to be ascertained, is found in the compound sporophores of Dacryo-
myces deliquescens. The presence of these cells is shown from without by their making
the parts of the sporophores where they are formed turn from their normal clear amber-
yellow colour to a dark orange. The hyphae swell and their cells become filled with
a densely granular substance of a dark orange colour. The cells separate from one
another when placed in water, and each may then give rise to a mycelium with the
characters which have been describedabove. Klebs especially has obtained compound
sporophores producing basidia from gemmae cultivated on microscopic slides.

The mycelia produced in nutrient solutions from the basidiospores of most of
the Coprini which have been examined and of Typhula may form small rod-like
gonidia, like those just described in the Tremellineae, before they arrive at the
formation of typical compound sporophores. These are long slender filiform
cylindrical bodies formed, often several side by side, in a tuft at the extremities or

332 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

sides of hyphal branches, and are divided transversely into shorter rods before or
after abscision (Fig. 161). These small rods are very abundantly and frequently pro-
duced in some species, as for instance in Coprinus lagopus, but not in all the individuals
which form basidia. In other species, as C. ephemeroides, they are few and rare; in
C. stercorarius, as may be gathered from what has been said above, they do not
occur at all. In Brefeld’s careful cultivations the rods always perished without ger-
minating, in C. lagopus sometimes after a doubtful commencement of germination ;
Van Tieghem’s statement with regard to their power of germination must therefore be
accepted with caution. From the facts in our possession we must speak of them as
gonidia the germination of which has not been observed.

A formation of gonidia of a certain kind has also been observed in the
Nidularieae, where young mycelial hyphae, if imperfectly fed, break up by transverse
divisions into cylindrical cells, which ger-
minate under favourable conditions and
develope new normal mycelia with peridia.

It appears therefore that in the best-
known species a formation of ‘gonidia’
may be introduced into the section of the
development between two successive gener-
ations of basidiospore-generations, in most
cases as a facultative occurrence depending
on external causes, in others perhaps as a
necessary or at any rate a very regular
process. More thorough investigation is
necessary on this point especially in the
Tremellineae; in the Nidularieae the acci-

FIG, x61. Coprinus lagopus, Fr. Mycelial hypha m with dental nature of the occurrence and its de-
a branch @ from which rods are being abjointed. 5 rods

or gonidia detached, some still d together in rows, i
cthesame isolated. After Brefeld, from Liirssen’s Handbook, pendence on external and occasional causes
a and & magn. 400, ¢ 600 times, is evident.

Finally, the observations on Sphaero-
bolus, to which we must now revert, show when compared with the foregoing that
the gonidia described above as gemmae in this Fungus have a prominent position in
the development, since the task of propagation devolves almost exclusively on them ;
at least the basidiospores are much behind them in this respect and in the natural
course of things need scarcely germinate at all.

For some time the course of the development in the Basidiomycetes was supposed to
be quite different from that which has now been described, and efforts were made
to show that it was different; it was thought that the compound sporophore, like
the sporocarp of the Ascomycetes, was developed from a fertilised archicarp, which
became surrounded in various ways, as in the Ascomycetes, with an envelope of hyphae.
Karsten’ has thrown out some doubtful hints in this direction since 1860, in connection
with Agaricus campestris. More decided suggestions of the kind arose from the
discovery of the development of the sporocarps of Erysiphe, and these were probably
the occasion of the paper of A. S. Oersted?, which described ‘oospheres’ formed

i Geschlechtsleben d. Pflanz. p- 50, and Bonplandia, 1862, p. 63.
? Verhandl. d. k. Dan. Ges. d. Wiss. 1 Jan. 1865.

CHAPTER V.—COMPARATIVE REVIEW.—-BASIDIOMYCETES. 333

as small branches on the mycelium of Agaricus (Crepidotus) variabilis, P., on which
1~2 slender adjacent branches supposed to be antheridiae usually did zof lay themselves,
while the oosphere, without experiencing any further changes, became surrounded by
a hyphal tissue which developed into the pileus.

The question was subsequently resumed in connection with specimens of Coprinus
cultivated on microscopic slides, especially by Reess', who thought he found spermatia
in the small non-germinating ‘rods,’ and archicarps in the swollen extremities of the
branches, but without clearly making out the participation of the two kinds of organs
in the formation of the compound sporophores. Van Tieghem ? studied the species
of Coprinus about the same time, and found spermatia in the small rod-like gonidial
cells, and also discovered archicarps, which were fertilised by conjugation with the
spermatia and then developed in very characteristic manner into compound sporo-
phores; he even obtained a hybrid form by crossing the two species, but he very
soon withdrew all these statements and has adhered from that time to the views
expressed above. It was unfortunate that the declaration of this change of opinion
coincided to the day with the first publication of Brefeld’s researches, and we must
allow him the merit of finally clearing up the matter, because, as regards Van Tieghem,
it would always have been a question which of the two diametrically opposite results
arrived at within a space of ten months was after all the right one.

Srction XCIII. We have no complete observations on the course of the
development in the many other Hymenomycetes and Gastromycetes. But all that is
known of them favours the view that their history 7 in general the same as that of
the species with which we are perfectly acquainted in the essential points above desoribed,
nor is anything known which could be a sufficient reason for objecting to this view.
Besides the agreement in form and structure in the mature state, there is the un-
varying fact that the commencements of the compound sporophores wherever dis-
covered are formed, without the interposition of intermediate members, from hyphal
bundles of the mycelium which have exactly the same origin as those which remain
purely vegetative. R. Hartig’s careful observations on the wood-destroying Polyporeae,
Thelephoreae, and Hydneae should be especially mentioned in this place in addition
to the cases noticed in the foregoing descriptions.

Secondly, the little that is known of the germination of the spores and of the first
products of germination accords with the observations to which attention has been
drawn above. This is not much; the spores of many Hymenomycetes when sown
put out simple or branched germ-tubes ; non-germinating ‘rods’ are formed, according
to Eidam’s observation‘, on Agaricus coprophilus, Bull. on the first commencement of
mycelia grown in a nutrient fluid, and they appear in strings that are crowded
together in tufts and twisted into curls and entangled with one another. In the great
majority of the Gastromycetes the first products of germination have not been
hitherto observed or the supposed observations are very doubtful®; germination may
in their case depend on special and hitherto unknown conditions, or the circumstances
may perhaps be the same as in Sphaerobolus.

No doubt would be raised as to the agreement of all the Basidiomycetes in the

1 Phys. Med. Ges. z. Erlangen, 14 Dec. 1874.—Pringsheim’s Jahrb. X, p. 179.
2 Comptes rendus de l’Acad. d. Sc. Paris, 80 (1875), p. 373-

3 Ibid., 81, p. 879 (15 Nov. 1875).

4 Bot. Ztg. 1875, p. 649.

5 See Hoffmann in Bot. Ztg. 1859, p. 217.

334 DIVISION II,—COURSE OF DEVELOPMENT OF FUNGI.

rhythm of their development, in accordance with the remarks in the preceding
paragraphs, if the statement that gonidia occur on the mycelia and compound
sporophores of the Hymenomycetes proved to be true. The statement has been made
only ina few isolated cases. The supposed gonidia mentioned by Oersted in Agaricus
variabilis, P. are strictly of this kind, also those of A. racemosus, P., A. vulgaris, P.,
Fistulina hepatica and Polyporus Ptychogaster, Ludwig. My own older remarks
on Nyctalis perhaps do not strictly or perhaps do not at all belong to this connection,
but they may nevertheless be mentioned here.

In the case of all these statements it is distinctly to be observed, that no one of
them puts the real nature of these gonidia or spores as they may also be called, and
their connection with the particular species of Hymenomycetes which forms basidia,
beyond doubt, for in no case is it clear whether they reproduce the hymenomycetous
form or something else, or, as may possibly happen, nothing at all; usually the first
beginnings of germination in the presumed gonidia have not been observed. The
possibility is nowhere excluded that they belong to parasites of the particular
Hiymenomycetes.

The slender stipe of Agaricus racemosus, Pers. which springs from a sclerotium
terminates in fully developed specimens in a pileus, which according to old existing
descriptions and figures has the typical structure of the Agaricineae. The stipe is
beset throughout its whole length with short hair-like spreading branches, which
were compared by Fries! and Berkeley? to the sporophores of the form-genus Stilbum,
because, like them, they abjoint at their extremities numerous spores (gonidia) arranged
in rows and forming together a small gelatinous head. In other specimens the
branching is more irregular and the primary stipe also ends in a head of gonidia.
The gonidia according to Tulasne?® are ellipsoid or elongated in form and. produce
long germ-tubes when sown in water.

On the extremities of short mycelial strands of Agaricus vulgaris Fr. Hoffmann *
saw here and there small cylindrical cells serially abjointed, and called them spermatia.

Short non-septate erect simple sporophores rise according to Oersted® from the
mycelium of Agaricus variabilis, P. and abjoint ellipsoid spores simultaneously in
a small head at their extremities, after the manner of Corda’s form-genus Cephalo-
sporium.

De Seynes observed a formation of ‘gonidia’ often in large quantities on the pileus
of Fistulina hepatica; these were abjointed singly or in tufts close beside one another
or in rows, and were of ellipsoid form, usually about 8 x in length, and furnished with
very thick brownish-red membranes. They were borne usually on relatively slender
copiously branched hyphae, which appeared in many cases to spring as branches from
the thicker hyphae of the substance of the pileus, and were found chiefly on the upper
side of the pileus, sometimes on its surface, sometimes at a depth of a centimetre in its
tissue, spreading through it oftentimes in enormous quantities. They were found in
every one of the many specimens examined by De Seynes from Europe, America, and
Asia. De Seynes observed only very feeble and almost doubtful attempts at germina-
tion in old material. My own early notes on the subject, which I have had no
opportunity of completing, confirm De Seynes’s statements to a great extent, but add,
that the hyphae which produce the gonidia may also occur on the under surface of
the pileus and between the tubuli of the hymenium, and that they were not found

! Epicris, p. go. ? Crypt. Bot. p. 365.
3 Fung. Carpol. I, p. 110. * Bot. Ztg. 1856, p. 158.
® Oversigten d. Verhandl. d. k. Dan. Ges. d. Wissensch. Jan. 1865.

CHAPTER V.—COMPARATIVE REVIEW.—BASIDIOMYCETES. 335

on all specimens. We can arrive at no certainty in the matter without a complete
account of their development and especially of their germination.

Corda’ has described a Fungus growing on old pine-wood under the name of
Ptychogaster albus, a round body of the size of a hazel-nut or even much larger, which
has the appearance of a Lycoperdon and is white when young, but when the spores
are ripe is of the colour of a brown clay. Its structure, however, is not that of a
Lycoperdon. It consists at first of a loose soft weft of hyphae, which radiate for the
most part from a more dense basal portion, their free sterile extremities terminating
in the periphery. The hyphae have many transverse septa and clamp-connections
at the septa. The spores are formed in the interior on the hooked or spirally twisted
ends of the branches of the hyphae ; these branches are converted into mucilage when
the spores are developed and disappear, so that the brown spore-dust lies among the
decaying remains of the hyphae. According to Tulasne? the spores are formed in
large numbers as round lateral protuberances on the filaments and in no fixed order ;
according to Cornu® the twisted hyphae break up each into a single row of spores.
Tulasne compares this Fungus to Pilacre Petersii, Berk. et Br.and Onygena faginea,
Fr. and suspects it to be a
gonidial form of an Ascomycete,
mentioning especially Poronia.
E. Fries* on the contrary con-
siders Ptychogaster to be a mon-
strous product of Polyporus
borealis, and Cornu thinks this
probable on account of the clamp-
connections which are so common
in the Hymenomycetes. F. Lud-
wig® has in fact recently found
specimens of Ptychogaster which
had a hymenium of Polyporus on
the under side, the side towards
the substratum. The elements of
the hymenium appeared to spring
directly from those of the Ptycho-

gaster, and no similar form of Fic. 162. Nyctalis asterophora, Fr. 4 a young specimen, in vertical
Polyporus Was found is the SE eae see nes Ae a 2 Bonar Sg
cinity. No more is stated, and caripe chlamydospore. 4 slightly magnified, 5 and c magn. 390 times.
careful artificial cultivation only

can show whether the two forms really belong to the same species, which Ludwig
names Polyporus Ptychogaster, or whether it is a case of cohabitation of two
species, or parasitism.

The ‘conidia’ reported by Richon *in Hydnum Erinaceus and Corticium dubium
require more thorough investigation in all points.

I have elsewhere’ represented the occurrence of two kinds of spores in the
sporophores of Fries’ Nyctalis asterophora as belonging to the cases which we are
considering here. The sporophores of this Fungus are developed in the same way
as in the gymnocarpous Agaricineae. The loose air-containing weft of delicate

1 Icon. II, p. 23.

2 Ann. d. sc. nat. ser. 5, IV, p. 290, and XV, p. 228, t. 12.

3 Bull. Soc. bot. de France, XXIII, p. 362.

* Summa Veg. Scand. p. 564.

5 Zeitschr. f. d. gesammten Naturwiss. 53 (1880), p. 424, tt. 13, 14.
® Bull. Soc. bot. de France, 1881, p. 180.

” Bot. Ztg. 1859, p. 385.

336 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

radiating hyphae, which forms the whole of the upper side of the pileus, produces
at an early stage and from all parts numerous stellate spores or macrogonidia of a
yellowish brown colour, which I named chlamydospores ; when fully developed it
is a yellowish brown layer, which may be 1 mm. in thickness and ultimately
decays (Fig. 162). Lamellae are formed on the under surface of large pilei, and on
them basidia which produce four spores, and are usually few in number. The tissue
of the under side of the pileus, which bears the lamellae when fully developed, is
distinctly different from that of the layer of chlamydospores both in the shape and
size of its cells. In young specimens, on the other hand, the Fungus consists entirely
of similar hyphae, and there is an uninterrupted connection between the hyphae of
the under side of the pileus and those of the chlamydospore-layer, the latter appearing
as branches from the former. In some cases no basidia or lamellae are formed.
Tulasne states that a third kind of spore is found in the layers of macrogonidia, namely,
small colourless cylindrical cells or microgonidia which are abjointed in long rows.

A second species, Nyctalis parasitica, Fr., which like N. asterophora grows on the
larger Agarici, especially Russula adusta, Fr., forms narrowly ellipsoid smooth macro-
gonidia in the interior of the whole of the tissue of the thick swollen lamellae, the
other parts of the pileus remaining free from them. Tulasne not unfrequently found
typical four-spored basidia isolated in the same lamellae as the chlamydogonidia,
but I never saw any in my specimens. The view that the gonidia are organs of
Nyctalis is founded with regard to both species on the fact, that the hyphae from
which they are produced are evidently branches from the rest of the tissue, as seems
to have been ascertained beyond doubt in younger specimens.

Tulasne! has declared against this view. Like Corda, Bonorden, and other writers
before him ? he holds that the chlamydospores (with the microgonidia of N. asterophora)
are organs of two Fungi which are parasitic on Agaricus parasiticus, a distinct species
which itself lives upon Russula and other forms, and produces more or less degenera-
tion in them, and he places these parasites in Hypomyces, a genus of the Sphaeriaceae
which lives on other Fungi, under the names of H. asterophorus and H. Baryanus.
The grounds of his judgment are the resemblance between these organs and those
of the same name in other species of Hypomyces which are known to be parasitic
on the Agaricineae, the fact, which I can vouch for, that the chlamydospores sometimes
arise isolated on the mycelium of Nyctalis which grows in or on Russula, and lastly
the occurrence of indubitable perithecia in company with the gonidia on Nyctalis
asterophora. He has not detected any defect in the investigation of the anatomy
and life-history of the plant, on which I founded my opinion.

Tulasne’s view is so very probable, that I have taken much pains to find out where
my mistake is, but repeated examinations have hitherto always produced the same
result. If we simply adhere therefore to the facts before us, we must abide by my
first view, especially since Agaricus parasiticus has never been found, as far as I know,
without a chlamydospore-apparatus, except perhaps where ät is replaced by Nyctalis
microphylla of Corda®. The structure also of the sporophore of N. parasitica is so
very different from that of N. asterophora, that the conjecture that the two forms
of Nyctalis are the same Agaricus parasiticus which has been differently altered
by different parasites, seems to me much more rash than my own opinion as expressed
above. Moreover an experiment of Krombholz by artificial cultivation of the plant
seems to afford support to my explanation. Krombholz * sowed the stellate spores of
N. asterophora on a young Russula adusta, and as he states with all due precautions,

' Ann. d. sc. nat. ser. 4, XIII, p. 5, and Sel. Fung. Carpol. III, 54, 59.
? See Bot. Ztg. 1859, p. 385.

® Icon. IV, Fig. 134.

* Essbare Schwämme, Heft I, p. 3.

CHAPTER V.— COMPARATIVE REVIEW.—BASIDIOMYCETES. 337

and observed in a few days the first beginnings of a mycelium make their appearance
exactly on the spots which had been sown, and on the ninth day the first commence-
ments of the compound sporophores, which reached their normal development and
maturity between that and the twentieth day. But even here the possibility of
parasitism is not absolutely excluded.

A notice of Sautermeister! to the effect that Exidia recisa may also have
ascocarps in old and shrivelled compound sporophores has never been confirmed, and
must have been founded on the settlement of a species of Ascomycete in old plants
belonging to the Tremellineae.

Section XCIV. If we cast a glance backward at sections LXXIV to XCIII, we
shall see that we must assume a direct affinity or phylogenetic connection throughout the
whole assemblage of the Basidiomycetes. The course of development is the same in
its main features wherever it has been ascertained. The organs which have been desig-
nated by the same name in the foregoing account, especially the basidia and basidio-
spores, must from the data before us be regarded as sfrzctly homologous. The Hymeno-
mycetes on the one side and the Gastromycetes on the other are evidently two
closely connected series. They are in general very different from one another, and
the difference lies chiefly in their compound sporophores, but they sometimes also
approach each other very nearly. Gautieria, and we may say also some forms of
Secotium, are evident connecting links between the groups of the Hymenogastreae
and Polyporeae. Gautieria which has all the characters of the Hymenogastreae,
but has its chambers open and covered with no peridium, may be compared
to a curled Merulius; the question naturally arises, whether the interior chambers
have been formed by differentiation or in some way directly corresponding to this
comparison.

If we could attribute a decisive value to the habit of the plants, we should dwell
upon the great resemblance between the stalked Hymenogastreae, like Secotium
erythrocephalum (Fig. 144) and a veiled Boletus, or still more perhaps that of
Polyplocium ? to the same species, though Polyplocium is too little known in its
earlier states. But among the Polyporeae there is a remarkable form Polyporus
volvatus, Pk., the Polyporus obvallatus of Berk. and Cook *, which considered by
itself must be placed with or close to the Hymenogastreae. Its sporophore, which
lives in the bark of trees, is a hollow spherical body flattened at the poles and about
the size of a hazel-nut, with a thick closed wall of leathery texture; its interior surface
is covered with the hymenium of a Polyporus on the part next the substratum and
is sterile on the opposite side.

That all the groups of the Gastromycetes converge towards the Hymenogastreae
directly or indirectly through the Lycoperdaceae, and that they may therefore be de-
duced phylogenetically from the Hymenogastreae, is a necessary conclusion from the
account which has here been given of them. Corda and Tulasne long since drew
attention to this connection, and to the affinity between the Hymenogastreae and
the Hymenomycetes which has been brought into prominence in the preceding

pages.

1 Bot. Ztg. 1876, p. 819.
2 See Berkeley in Hooker's Journ. II. 201, and Corda, Icon. VI.
3 Ellis, North American Fungi, No, 307.

[4] Zz

338 DIVISION I1.—COURSE OF DEVELOPMENT OF FUNGI.

It would be possible to assume another point of connection between the
Hymenomycetes and the Gastromycetes, if we regard the mode of development of the
compound sporophore from one side only. Then Amanita among the Hymeno-
mycetes would approach nearest to the Gastromycetes, because the first development
of the parts in one and the other is the result of differentiation zn the interior of the
primordial coil of hyphae. Brefeld, in connection with some former suggestions of
my own of this kind, has recently given decisive weight to the above consideration.
But then Amanita is closely connected in all other respects with the series of the
Agaricineae ; the agreement between their propagative and especially their hymenial
apparatus and that of the Gastromycetes is the very smallest possible. We might dis-
regard this fact, and venture a jump across the intervening space, if no better means
of connecting these groups could be found. But since we have such a mode before
us, and at the same time there is no ground for assuming the existence of two points
of union, the jump need not be made. The facts lead to the other conclusion, that
the development of the compound sporophores by internal differentiation, called
above the angiocarpous, makes its appearance at two widely separated points within
the group of the Basidiomycetes, namely, in the series of the Agaricineae and in that
of the Polyporeae. From the Polyporeae it leads further on to the formation of the
Gastromycetes.

After the special descriptions which have already been given of the complex
Lycoperdaceae and especially of the Phalloideae with their strange forms and differ-
entiations of tissue, nothing further is required to show that they are the most highly
developed of the Basidiomycetes. It is apparent also that all the series of the
Basidiomycetes converge towards the more simple Thelephoreae and Tremellineae
and meet in them. These forms may therefore be a connecting link between the
Basidiomycetes and the rest of the Fungi, and since no such link is known elsewhere,
there is a strong antecedent probability that this exact point of connection is to be
found there. Comparison shows an evident close affinity between the Tremellineae
and the tremelloid Uredineae (see page 283). In fact there is no essential difference
between the two groups either in the course of development or in the structure of the
sporophores. It is unnecessary to repeat here what has been already said respecting
the former. If special stress is to be laid on the formation of gonidia and sprouts in
the germination of the Tremellineae, this phenomenon is undoubtedly repeated in the
abjunction, so common in the Uredineae, of ‘secondary’ and even tertiary sporidia on
primary sporidia which do not at once find a substratum favourable to nutrition when
they first germinate. These sporidial sprouts are produced, as far as is known, only
in small numbers, but this constitutes only a quantitative difference and has an
evident relation, as may be remarked in passing, to the strictly parasitic mode of life
of the Uredineae. The conformation of the compound sporophores in the members of
both divisions is to a certain extent the same. The organs termed basidia in
Auricularia (page 306) do not differ in any essential point from the teleutospores of
Chrysomyxa and Coleosporium ; the forms too of the basidiospores or sporidia may
be almost said to be the same. Uredineae like Leptochrysomyxa Abietis are simply
Tremellineae, and would be placed with them in the natural system if their allies
which form aecidia were not known. The same may be said without exaggeration
of the Leptopuccinieae, for the teleutospores of the latter, which must form one term

CHAPTER V.—COMPARATIVE REVIEW.—BASIDIOMFCETES. 339

of the comparison, are not more unlike the basidia of the Tremellineae than many of
these are unlike one another. The gelatinous character also of the membranes in
many Uredineae might also be mentioned, if such an argument were not too weak for
serious consideration. The statements made in former paragraphs show that the
teleutospores, or in some cases perhaps only the promycelia developed from them, in
the tremelloid Uredineae, are not only very like the basidia of the Tremellineae, but
strictly homologous with them. ‘There is the same relation between the sporidia and
the basidiospores,

Further there can be no doubt, according to the facts stated above on page 283,
that the teleutospores of the tremelloid Uredineae are strictly homologous phylo-
genetically with the teleutospores of the forms which produce aecidia, and that the
two sections together form the sharply defined group of the Uredineae. The rhythm
of the development in the species which form aecidia shows that this group belongs
to the series of the Ascomycetes (see page 132). The Basidiomycetes are thus
connected with the series of the Ascomycetes through the Tremellineae and the
tremelloid Uredineae.

The teleutospores of the Uredineae, if referred to the general course of develop-
ment in the Ascomycetes, come under the definition of gonidia, and the basidiospores
of the Basidiomycetes, which are phylogenetically homologous with them, necessarily
come under the same idea. If those members of the development are said to be
homologous which occupy corresponding places in the course of the ontogenetic
development, the homology between the series of the Ascomycetes and the
tremelloid Uredineae and Hymenomycetes is zuierrupied and not restored in the sense
explained on page 123.

And now if in deciding with regard to the phenomena of relationship which arise
out of the similarity of the development we hold to the view that the forms in question
are all phylogenetically connected, the question arises, whether in passing from the
tremelloid Uredineae and Basidiomycetes to the Uredineae with aecidia we should
suppose that the latter proceeded from the tremelloid Uredineae or Basidiomycetes
and therefore acquired the sporocarp as a new member of the development which was
wanting in the earlier series; or whether the converse is not the more probable course
of the phylogenetic development, and the sporocarp known as the aecidium has been
ejected from the ontogenetic development of the tremelloid Uredineae and Basidio-
mycetes. One of the two things must obviously have taken place. In the first case the
phylogenetic formation of the Uredineae bearing aecidia would be an act of progressive
development, for a new and highly differentiated member would be added to those
previously existing in the development: in the other case the development would be
retrogressive, since this section of it would have disappeared. It was remarked above
on page 285 and on a former occasion ' that the absence of every kind of intermediate
form is opposed in this case to the theory of a progressive development; there would
be a jump from the tremelloid Uredineae to the perfect species with aecidia, and we
must put up with it if it cannot be avoided, but our experience of known cases of
progressive development does not add to its plausibility. On the other hand, there

} Bot. Ztg. 1879, p. 825.
Z2

340 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI.

are analogous cases known in the Ascomycetes which illustrate the opposite theory
of a retrogressive development.

An attempt was made in former sections to show that the series of the Ascomy-
cetes connects with the Algae which form oospheres through the Peronosporeae
and Zygomycetes and their allies, and may be derived from them in progressive
succession; also that the Uredineae are united as a member to this series. This view
may at present be said to be the one which accords best and most naturally with the
facts as known to us. But if this is the accepted view, we must necessarily adopt
that one of the alternative assumptions, which makes the tremelloid Uredineae and
Basidiomycetes degenerate descendants of those members of the series of the Ascomy-
cetes, to which observation directly points; otherwise they must have a double phylo-
genetic origin, which can hardly be admitted in so comparatively narrow a group as
the Uredineae. The series of the Basidiomycetes when once parted off advanced to
a high and peculiar development, as is shown by the Amanitae, Phalloideae, Sphaero-
bolus, and other forms. .

The views which have been developed in the preceding paragraphs explain the
intimation given above on page 331 respecting the terminology of the reproductive
organs in the Basidiomycetes. The word gonidia has a different meaning here from
what it has in the series of Ascomycetes, where it was used with reference or in
opposition to the carpospores (page 129); in the Basidiomycetes, where there are
no carpospores, the term gonidia is applied to certain spores other than the daszdio-
spores, and these are themselves phylogenetically homologous with certain gonidia of
the Uredineae. The question whether the gonidia of the Tremellineae can be
considered to be homologous with the uredogonidia of the Uredineae may fairly be
termed a needless one; certainly there is little real objection to be made to this
view. Still the question necessarily connected with it, whether the ‘rods’ observed
hitherto without germination in some Hymenomycetes (page 332) are homologous
with the gonidia of the Tremellineae, or are spermatia derived through the descent
from the Ascomycetes, had better be left for the present without an answer. Further
observations will perhaps determine these matters.

The views here expressed respecting the genealogy of the Fungi are of course only
an attempt to bring the separate facts at present known into the unity of a single
scheme ; every displacement in the basis of facts may necessitate an alteration in
the scheme.

The near connection which has been pointed out between the Hymenomycetes and
the Uredineae may well be regarded as an established fact that is not likely to be
set aside. There are certain alleged reasons why the former should be considered
to be derived phylogenetically from the latter, and not vice versa. These are also
good reasons in the present state of our knowledge, but the progress of inquiry may
affect them, especially as they are derived, not only directly from the subject-matter
in question, but partly also from remoter sources.

Starting from the same facts we may even now arrive at other results than these,
as appears from Brefeld’s views, though not without the help of some very bold
hypotheses. What is to be said concerning these views will be found in a former
treatise of my own? to which the reader is referred.

1 Schimmelpilze, III and IV.
? Beitr. IV, p. 131.

CHAPTER V.—COMPARATIVE REVIEW.

BASIDIOMPCETES. 341

The balance of argument has been already shown in the text to be in favour of
considering the Hymenomycetes as united in a single series with the Tremellineae
and these with the series of Ascomycetes through the Uredineae. The details of
the connection, the question whether it is effected by several species and which
those species are, have yet to be settled.

Certain observations gave rise some time since! to the conjecture that there were
close relations between the Basidiomycetes and the Ascomycetes, the Basidiomycetes
being the gonidial forms of perfect existing Ascomycetes. The conjecture originated
in the observation of indubitable asci in pustule-like swellings in. old lamellae of
Agaricus melleus, and in phenomena observed in Nyctalis and mentioned on page 335.
The finding of perithecia, which according to Tulasne are connected with the star-
shaped spores of N. asterophora, was rather in favour of this view than against it.
I regarded these Nyctalis-spores and the asci of A. melleus as organs of the particular
species of the Hymenomycetes, because they seemed to proceed directly from hyphae
of the pileus. At present I agree with Tulasne, as was intimated at page 336, in
thinking that it is most probably a case of parasitism, and I spoke of the ascogenous
hyphae of A. melleus at page 266 by their parasitic name of Endomyces. But since
the parasitic nature of Endomyces and the defect in the former observations have
not yet been shown, this brief further notice of the subject may be permitted in
this place. In case the earlier statements should be confirmed, and it should be shown
that Tulasne’s perithecia belong to Nyctalis asterophora, the views here advanced would
be subject to some alteration, since it would be necessary to assume that the Basidio-
mycetes are phylogenetically connected with the Ascomycetes, not at one point only,
but at several. But in the present state of our knowledge it is difficult to admit any
more points of connection in the ontogenetic cycle of the species of Ascomycetes with
the greater number of Basidiomycetes.

Literature (see also p. 116).
a. Hymenomycetes.

The works of Persoon, E. Fries, Corda (Icones fungorum), Tulasne (Carpologia I), are
the chief works to be consulted. Only the more important original treatises
are cited below. Some works have been noticed already in the text.

F. NEES V. ESENBECK, Plantar. mycetoidarum, &c. Evolutio (Entw. d. Agaricus
volvaceus) in N. Act. Acad. Leop. Carol. XVI, pars I.

Jos. SCHMITZ, Ueber d. Bildung neuer Theile bei d. Hymenomyceten ;—Id., Ueber d.
Längen-Ausdehnung bei d. Pileaten (Linnaea, XVI, 1842) ;—Id., Ueber Entw. Bau
u. Wachsthum von Thelephora sericea u. hirsuta (Linnaea, XII, 1843, p. 417).

BONORDEN, Allgem. Mykologie, pp. 156-196 et passim ;—Id., Beobachtungen ii. d. Bau
d. Agaricinen (Bot. Ztg. 1858, p. 201).

H. HOFFMANN, Pollinarien u. Spermatien von Agaricus (Bot. Ztg. 1856, p. 137) ;—Id.,
Beitr. z. Entwicklungsgesch. u. Anatomie d. Agaricinen (Bot. Ztg. 1860, p. 389) ;—
Id., Icones analyticae fungorum, I-IV, Giessen, 1861-1865.

DE Bary, Zur Kenntn. einiger Agaricinen (Bot. Ztg. 1859, p. 385).

J. DE SEYNES, Organisation des Champignons supérieurs (Ann. d. sc. nat. ser. 5, I,
p- 269) ;—Id., Recherches sur 1. végétaux inférieurs, I. Des Fistulines, Paris, 1874.

TULASNE, Obs. sur l’organisation des Tremellinees (Ann. d. sc. nat. ser. 3, XIX,
p. 194) ;—Id., Nouvelles notes sur les fungi Tremellini et leurs alliés (Ann. d.
sc. nat. sér. 5, XV). See also sér. 5, IV.

M. Woronitn, Exobasidium Vaccinii (Ber. d. naturf. Ges. Freiburg, 1867).

©. BREFELD, Bot. Unters. ii. Schimmelpilze, III ;—Id., Bot. Unters. ii. Hefepilze, V,
Leipzig, 1883.

1 Bot. Ztg. 1859, p. 404.

342 DIVISION II—COURSE OF DEVELOPMENT OF FUNGI.

VAN TIEGHEM, Sur le développement du fruit, &c. des Basidiomycétes et des Asco-
mycétes (Bull. Soc. bot. de France, 1876, p. 99, and Bot Ztg. 1876, p. 161).

R. HARTIG, Wichtige Krankh. d. Waldbäume, Berlin, 1874 ;—Id., Die Zersetzungs-
erscheinungen d. Holzes d. Nadelholzbäume u. d. Eiche, Berlin, 1878.

b. Gastromycetes.

The chief sources of our knowledge of the morphology and anatomy of the Gastro-
mycetes are the two following works :—

Corpa, Icones fung. II, V, VI.

TULASNE, Fungi hypogaei, Paris, 1851.

In Corda will also be found many reproductions especially of short and interesting
descriptions of exotic forms by Berkeley in Hooker’s Journal.
After these—

MICHELI, Nova Plant. Genera, 1729 (Phallus, Clathrus).

BERKELEY in Annals and Mag. of Nat. Hist. 1839, and Ann. d. sc. nat. sér. 2,
XII, 1842, p. 160.

VITTADINI, Monographia Lycoperdineorum (Mem. Acad. Torino, V, 1842).

J. SCHMITZ, Ueber Cyathus (Linnaea, XVI, 1842).

TULASNE, De la fructification des Scleroderma comparée A celle des Lycoperdon et
des Bovista (Ann. d. sc. nat. ser. 2, XVII);—Id., Sur les genres Polysaccum et
Geaster (Ann. d. sc. nat. ser. 2, XVIII, 1842) ;—Id., Recherches sur l’organ. d.
Nidulariees (Ann. d. sc. nat. ser. 3, I, 1844) ;—Id., Description d’une nouvelle
espéce de Secotium (Ann. d. sc. nat. ser. 3, IV, 1845) ;—Id. in Exploration
sc. d’Algerie, p. 434, Tab. 23 (Development of Clathrus). On the same subject
see Berkeley in Hooker’s Journ. of Bot. IV, p. 68.

v. SCHLECHTENDAL u. MÜLLER, Mitremyces Junghuhnii (Bot. Ztg. 1844, p. 401).

BONORDEN, Mycologische Beobachtungen in Bot. Ztg. 1851, p. 18 (Phallus, Sphaero-
bolus) ;—Id., Die Gattungen Lycoperdon u. Bovista (Bot. Ztg. 1857, p. 593).

ROSSMANN, Beitr. z. Entw. d. Phallus impudicus (Bot. Ztg. 1853, p. 185).

JuL. SacHs, Morphologie d. Crucibulum vulgare, Tul. (Bot. Ztg. 1855).

v. SCHLECHTENDAL, Phalloideen (Linnaea 31, 1862), with copious notices of the
literature of the subject.

HOFFMANN, Icon. analyt. Fungor. II, p. 33 (Hymenogaster).
De Bary, Beitr. z. Morph. u. Phys. d. Pilze, I, 1864 (Phallus).

R. HESSE, Mikroskop. Unterscheidungsmerkmale d. Lycoperdaceengenera in Pring-
sheim’s Jahrb. X, p. 384 ;—Id., Keimung d. Sporen v. Cyathus striatus in Pring-
sheim’s Jahrb. X, p. 199.

N. SOROKIN, Développement du Scleroderma verrucosum (Ann. d. sc. nat. ser. 6, III).
E. EIDAM, Keimung u. Entwickl. d. Nidularieen in Cohn’s Beitr. z. Biol. II.

O. BREFELD, Bot. Unters. ü. Schimmelpilze, III, p. 174.

A. PITRA, Ueber Sphaerobolus (Bot. Ztg. 1870, p. 681).

SCHRÖTER, Entw. v. Tulostoma in Cohn’s Beitr. II, p. 65.

ED. FISCHER, Zur Entwicklungsgesch. d. Gastromyceten in Bot. Ztg. 1884 (Sphaerobolus,
Mitremyces).

DIVISION III. MODE OF LIFE OF THE FUNGI.

CHAPTER VI. PHENOMENA OF GERMINATION.

l. CAPACITY OF GERMINATION AND POWER OF
RESISTANCE IN SPORES.

Section XCV. The greater number of known spores in the Fungi, the word
spore being taken in the meaning assigned to it on page 128, are capable of
germination from ‘he moment that they are ripe. In a smaller number of known
forms this is not the case; the spores do not germinate till after they have passed
through a perrod of rest which follows upon their maturity.

Examples of the first kind, that is, of spores which germinate immediately
after maturity, are all ascospores, most spores of the Hymenomycetes, the majority
of the forms known as gonidia, the oospores of some Saprolegnieae, as Achlya
spinosa, A. apiculata, and Aplanes (section XL).

Some spores are capable of germinating even before maturity, that is, before
they have reached the condition which according to empirical rules indicates
maturity (see page 59). The gonidia of the Saprolegnieae, for example, may omit
their regular swarm-cell period in cultivated specimens and germinate beneath the
cover-glass!; the. ascospores of Sordaria fimiseda in Woronin’s? experiments
showed themselves capable of germination long before the completion of their
definitive membrane and their discharge from the ascus, and similar cases are not
unfrequent among the Ascomycetes.

The period of time during which spores of this category retain the power of
germination, where the conditions are unfavourable to germination and the spores
are not subjected to any serious injury, varies in different species and individuals and
according to the form of the spore. It is short in the comparatively watery and
turgescent gonidia of the Peronosporeae, and in the uredospores, aecidiospores, and
sporidia of the Uredineae, lasting where the spores are not quite dried up for a few
weeks, seldom for a few months, and coming to an end, as far as we know at
present, with the summer in which the spores were matured. Gonidia, for example, of
Cystopus candidus which were not perfectly air-dry continued capable of germination
6-8 weeks, those of Phytophthora infestans for 3 weeks, perfectly air-dry gonidia
of the latter species (caught on glass-plates) lost their power of development in 24 hours.
Similar results were obtained in the case of the spores of the Uredineae mentioned
above. The ripe swarm-spores of the Saprolegnieae and Peronosporeae remain capable

1 Thuret in Ann. sc. nat. sér. 3, XIV, t. 22.
? Cited on page 262.

344 DIVISION III-—MODE OF LIFE OF THE FUNGI.

of germination for a short time only after completing their brief period of swarming
and die if the conditions are unfavourable to germination. But the diplanetic spores
in these groups (see pages 108, 143) are to some extent exceptions to this rule, since
they may continue alive and unaltered for days and weeks, perhaps longer, after
entering upon the transitory period of rest, if the conditions required for their further
development, especially a sufficient supply of oxygen, are excluded. Further de-
velopment begins if they are placed in fresh water containing oxygen, and first of
all the second stage of swarming.

But many spores of this first category, belonging to Fungi which do not live in
water, retain their vitality and power of germination for a long time, if they are
protected and kept in an air-dry state.

It has been proved that the spores of many common Fungi will remain alive for
a period varying 1-2 years; for example the ascospores of Penicillium glaucum have
germinated when two years old, the gonidia after 13-13 years; the spores of
Coprinus stercorarius! when more than 1 year old, the gonidia of Aspergillus niger
when of the same age, of Sordaria curvula after 28 months, of Botrytis Bassii and of
allied forms of Isaria after 1-2 years, of Mucor stolonifer after t year. ‘The gonidia
of Phycomyces nitens, a species nearly related to Mucor Stolonifer, is a good
example of specific and individual variation. Van Tieghem? found that they hardly
retained their vitality for 3 months, and I once observed the germination of gonidia
which were 10 months old, while others had lost their vitality after the space of 1
month.

The resting-spores of some Ustilagineae are very long-lived according to
Hoffmann and v. Liebenberg*; the latter observer found the spores of Tilletia Caries
from a herbarium specimen capable of germination after 8} years, those of Ustilago
Carbo after 74 years, of U. Tulasnei and Urocystis occulta after 64, of Ustilago
Kolaczeckii, U. Crameri and U. destruens after 53 years, of U. Rabenhorstiana
after 34 years. In some of the forms here mentioned, as U. Carbo, the maximum
of possible duration appears to be given; in others as Tilletia Caries the vitality
may continue beyond the time specified, which is given for the oldest material at
command, and this showed such active power of germination that it may be assumed
that still older spores would have retained the power.

Gonidia of Aspergillus flavus * proved in one case to be capable of germination
after having been kept in a dry state for 6 years, those of A. fumigatus ® for as many as
10 years.

Well-known examples of spores which require to go through a period of
rest before they are capable of germination are found in the oospores of the Pero-
nosporeae and most Saprolegnieae, the zygospores of the Mucorini, the organs
described above as resting-spores in the Chytridieae, Protomyces, and other forms,
the teleutospores of most Uredineae—with the exception however of Leptopuccinia,

1 Brefeld, Schimmelpilze, II, 76; III, 15.

? Van Tieghem et Le Monnier in Ann. d. sc. nat. ser. 5, XVII, 288.

* Hoffmann, in Pringsh. Jahrb. II, 267.—v. Liebenberg, Ueber d. Dauer d. Keimkraft d. Sporen
einiger Brandpilze (Oesterr. Landw. Wochenblatt, 1879, Nr. 43, 44).

* Brefeld, Schimmelpilze, IV, p. 66.

> Eidam, in Cohn’s Beitr. z. Biolog. III, 347.

CHAPTER VI.—PHENOMENA OF GERMINATION, 345

Coleosporium, Leptochrysomyxa, Chrysomyxa, Cronartium, Hemileia, and others, in
which the teleutospores belong to the first category,—the megalogonidia or resting
gonidia of Hypomyces and its allied forms, some spores of the Ustilagineae and
some others.

The period of rest in many of these cases is observed to last for a fixed time,
and to coincide with certain periods of vegetation and seasons of the year. The
teleutospores, for instance, of the Uredineae, the most frequent representative of
which is Puccinia graminis, are dormant during the winter. The teleutospores of
Puccinia ripen at the end of summer and during the autumn and germinate under
favourable conditions in the following spring, and it is difficult to procure their
germination before that time even under cultivation. This appears also to be the
history of the oospores of the Peronosporeae which do not live in water, and of the
resting-spores of Protomyces macrosporus and some species of Synchytrium, S.
Anemones for instance and S. aureum, &c. (see page 167), which all ripen in the
summer and do not germinate till the next spring, and in their case also it is found
difficult to shorten the resting period in plants under cultivation.

It is different, according to Woronin!, with the resting-spores of Tuburcinia
Trientalis among the Ustilagineae and of Sorosporium Saponariae, which ripen in
the course of the summer and are not capable of germination before the end of
September of the same year.

This coincidence with a fixed period of the year is at least not a general rule in
the zygospores of the Zygomycetes, in the oospores of many Saprolegnieae® (the
Pythieae), and in the resting-spores of Synchytrium Taraxaci, though it may occur
in some cases (Sporodinia, Synchytrium). In the absence of this coincidence we
can only speak of a necessary period of rest which lasts some weeks or months and
varies in different species and individuals.

We have no exact observations on the maximum of the resting time possible
under favourable circumstances in the case of species which are not confined to fixed
seasons of the year. It may extend to a year and probably may exceed a year
in the spores of Pythium proliferum kept under water. Our knowledge of the
Zygomycetes and Saprolegnieae would lead us to suspect that, when the conditions
required for germination are excluded, the power of germination ceases at an
earlier period in them than in the more hardy forms, which retain their vitality more
than a year without being obliged to go through a period of rest.

The forms in which the resting time coincides with fixed periods of the year
appear as a rule not to retain their powers beyond the favourable time for
germination which follows their maturity, or not to retain them long beyond that
time. Teleutospores of Puccinia graminis which have lasted during the winter
germinate with great readiness in the spring which succeeds their period of ripeness,
more slowly and more infrequently during the following summer months, and I was
unable to procure their germination after August or in the spring of the second year.
It is the same with other allied species. Woronin failed to make the spores of
Tuburcinia Trientalis germinate when they had remained without germinating from

1 Beitr. V. See also before on page 180,
? See De Bary, Beitr. IV.

346 DIVISION III.—MODE OF LIFE OF THE FUNGI.

the time of their maturity till the late autumn; and it would appear, from the
observations which we possess, that the regularly hibernating oospores of the
Peronosporeae and the winter-spores of the Chytridieae, &c. behave in a similar
manner, though no exact researches have been made into the possible maximum
duration of their resting time.

The power possessed by the spores of Fungi of withstanding the effects of
injuries caused by agencies from without varies very much in individual cases.
Disregarding the effect of poisonous bodies, we have to consider under this head the
withdrawal of water, extreme temperatures, and mechanical attacks.

As regards mechanical injury, Van Tieghem' found that some ripe spores—gonidia
of Phycomyces, Pilobolus oedipus, Mortierella reticulata, and zygospores of Sporodinia
and Mucor fusiger—when they are wounded or cut into not too small pieces, have
the power of healing the surfaces of the wound by forming a new protoplasmic
pellicle and a new membrane, or, if the lesion is slight and partial, they can divide
into daughter-cells, and each of these cells and each of the cicatrised fragments
continues or becomes capable of germination if the circumstances are favourable.

Some spores are very sensitive to the wethdrawal of their water which is effected
by drying them in moderately warm air (20-22° C). This is the case with swarm-
spores developing beneath the water as well as the gonidia abscised in the
Peronosporeae mentioned above, and with the short-lived spores of the Uredineae.
The example of Phytophthora infestans shows that these spores lose their powers of
germination quickly in the air-dry state even after a period of 24 hours. It would
appear also that the oospores of the Saprolegnieae which ripen under water cannot
bear being dried in the air at an ordinary temperature. It is estimated that at least
95 per cent. of the ripe ejected spores of Sclerotinia ciborioides lose their power of
germination if they are kept dry in the air on glass plates for 12 days in a temperature
of about 20° C.

Occasional observations seem to show that the spores of many Lichen-fungi are

among those which will not bear desiccation, but the point requires more thorough
investigation.
"It is evident that the spores which we have been describing form a very small
part of the whole number; the great majority of the spores of Fungi retain their
power of germination for a long time in the air-dry state. Some display great power
of resisting high temperatures and must therefore be able to bear the artificial
extraction of a large proportion of the water which they contain.

Resistance to extreme temperatures is shown more especially in relation to a
high degree of cold. The spores which were recently spoken of as regularly
hybernating in our temperate climates will endure a cold of —15° to —25°C. without
having their power of germination in the least affected. This experience justifies
us in assuming the same or a similar power in the majority of the other long-lived
spores mentioned above. This was confirmed by Hoffmann in the case of Ustilago
Carbo and U. destruens, Trichothecium roseum, Fusarium heterosporum, Penicillium
glaucum, Botrytis cinerea, and by Schindler * in that of Tilletia Caries.

1 Ann. d. sc. nat. ser. 6, IV, p. 315.
? Wollny’s Forschungen a. d. Agriculturphysik, III, p. 288.

CHAPTER VI.—PHENOMENA OF GERMINATION. 347

The behaviour of Saccharomyces Cerevisiae, ıhough not strictly belonging to
this connection, may be adduced to show that Fungus-spores are capable of bearing
very low degrees of temperature, for some only of its cells, according to Schumacher’,
were killed by a temperature of —113.75° C., while others lived and retained their
powers of growth.

On the other hand, many spores, especially those that are long-lived, can endure
extremely high temperatures without losing their vitality. Some observations show
that the length of the time to which they are exposed to the heat is an important
element in the case. The dry spores of a certain number of Fungi are not killed by
a heat which considerably exceeds 100° C. According to Nägeli it may be said that
a temperature of 130°C. is necessary to secure their destruction. But the death-point
of the spores of Fungi is often much lower than this in water or watery vapour, and
it has not been shown that any can under these circumstances survive a temperature
of 100° C.

According to H. Hoffmann the dry spores of Ustilago Carbo and U. destruens
support unharmed a temperature of from 104° to 128°C.; the spores of U. Carbo are
killed in a chamber filled with vapour at a temperature between 58°.5° and 62” C.,
those of U. destruens by a temperature of from 74° to 78° C. in the space of an hour,
and by one of from 70° to 73° C.in 2 hours. Tilletia Caries, on the other hand, will
bear according to Schindler a temperature of 95° C. if dry, but not more than that.
According to Payen* the spores of a mould found in bread, Oidium aurantiacum, can
endure a temperature of 120° C.; at 140° C. they were discoloured and killed.

Pasteur’s researches showed that the spores of Penicillium glaucum remain
unaltered in dry air at a temperature of 108°C. Many, but not all, lose their power of
germination at 119° to 120°C.; all lose it very quickly if the temperature is raised to
between 127° and 132°C. The limit is similar in ‘ Ascophora elegans’ (a species of
Mucor). Similar results were obtained from experiments on some spores of uncertain
origin mixed with dust, among which Botrytis cinerea, P. (gonidia of Peziza Fuckeliana)
or a closely allied form may be certainly distinguished; these bore a temperature
of 120°C. Spores suspended in a fluid which was heated up to 100° C. were always
killed in Pasteur’s experiments.

Against these statements must be placed the results of Tarnowsky’s researches
communicated by Sachs‘, according to which spores of Penicillium glaucum and
Mucor stolonifer when heated in air to a temperature of from 70° to 80° C. during
1-2 hours very seldom germinated, and were killed by a temperature of from 82°C. to
84°C.; they lost all vitality when warmed in a fluid up to from 51°to 55°C. We may
just mention some older statements of J. Schmitz* on this subject, which certainly
stand much in need of investigation.

The foregoing statements show that the spores of the Fungi are similar in
character to the organs with analogous functions in other plants. They afford

1 Sitzgsber. d. Wiener Acad. 70, 1 Abth. Juni, 1874, where other literature is cited. See also
Pfeffer, Physiol. II, 438.

2 Compt. rend. XXVII, p. 4.

® Lehrb. Auflage 4, p. 699.

* Verhandl. d. naturh. Ver. d. Rheinlande, II (1845).

348 DIVISION III-—MODE OF LIFE OF THE FUNGI.

special examples of the general rules regarding capability of germination, resistance,
&c. which hold good in those organs.

The theoretical explanation of the phenomena is therefore the same as in
analogous cases outside the Fungi and presents the same difficulties. This is not the
place to discuss this question, and the reader is therefore referred to physiological
works, and especially to the chapter which deals with it in Pfeffer’s Physiology.

It is hardly necessary to call attention once more to the consideration, that the
particular phenomena and characters change or may change from one case to another,
and that consequently the phenomena to be expected in one Fungus-spore cannot be
concluded with certainty from those of another, though it may be an allied form ; each
must be investigated for itself. This applies as much to spores of the same name in
different species of Fungi as to differently named spores in the same species. More-
over the results of enquiries into persistence and resistance show individual differences
in similar spores. For we not only see germination more difficult and slower under
otherwise similar conditions near the limits of persistence and resistance—the gonidia
of Aspergillus flavus, for example, germinate at once when fresh, but not till the
conditions for germination have been in operation for fourteen days when they have
been kept in a dry state for six years,—but some spores die sooner when approaching
those limits than other similar ones. These differences may be due to internal
causes which may perhaps be summed up in the words dissimilar maturation; or
possibly, after similar maturation, some spores are better protected than others against
slowly operating and modifying causes acting from without, and this it is extremely
difficult or impossible to determine with certainty’. But we must certainly not
disregard these differences when dealing practically with the question, and it is possible
that they have been the occasion of some of the discrepancies in the foregoing
statements,

There is another point which is also sufficiently obvious, namely, that the
characters described above imply adaptations, sometimes of a rougher, sometimes of a
more delicate kind, to definite modes of life. Two instances of this may be given.
The spores of ordinary Moulds,—of Penicillium, Eurotium, Aspergillus, and the Mu-
corini, and the gonidia of many Ascomycetes,—which are capable of germination as
soon as they are ripe and are also of a hardy nature, continue when they are once
matured to be for a long time always ready for further development if they meet with
the necessary conditions, and this, it may be said, may happen at any spot and at
any time in the case of these Fungi, because they have a very wide field of choice as
regards the nature of the substratum (see section XCVII). The teleutospores of Puccinia
graminis, which were described above as passing normally through the winter in a
dormant state, find the most favourable conditions in the ensuing spring, when their
power of germination is at its best, not only for germination but also for the further
development of the short-lived sporidia, which are the products of their germination ;
the conditions are favourable to the sporidia, because the danger of desiccation is
comparatively small in the moist cool spring-time, and there is young foliage on the
Berberis-plants into which the germ-tubes from the sporidia must penetrate to secure
their further development (see section CX). In autumn, when the teleutospores are

1 See on this point for example v. Liebenberg, as cited on page 344.

CHAPTER VI. —PHENOMENA OF GERMINATION. 349

mature, this condition for their development is almost entirely wanting, and the
height of summer which follows upon their regular time of germination is equally
unfavourable; the phenomena connected with their powers of germination are
closely accommodated to these circumstances. The teleutospores of this Fungus.
are at the same time the only means, or if we take some doubtful and exceptional
cases into consideration almost the only means, by which the plant lives through the
winter in these latitudes, for all the other organs die as a rule at the beginning of
winter. Exactly similar conditions prevail mulatis mutandis in the case of the
spores which normally live through the winter, of other Uredineae, of Protomyces,
Synchytrium, and the Peronosporeae, of Cystopus Portulacae in a remarkably
striking manner in Germany, of Tuburcinia Trientalis and some others.

These cases of exact adaptation to the function of hibernation are connected
with a long series of other cases within the affinity of the forms mentioned in which the
above characters in the spores are subject to very manifold madifications to meet new
adaptations in the life-conditions of the plants. Thus, for instance, in the alliance of
Puccinia graminis we come to the Leptopuccinieae with a mycelium which lives through
the winter, and spores which are usually short-lived and germinate as soon as they are.
ripe, and still further to the Chrysomyxae with a mycelium which also lives through
the winter, and a copious supply of spores which are all short-lived and can ger-
minate only in the summer in which they are formed (see sections LXXXII, CX).
Similar cases occur everywhere in other groups.

2, EXTERNAL CONDITIONS OF GERMINATION.

Section XCVI. The external conditions necessary for the commencement of
germination in the spore are in general the same as are required for the germs and
seeds of other plants; a certain temperature of the environment, a supply of oxygen and
water, and in some cases also of nutrient substances.

The cardinal points in the germination-temperature of spores have been exactly
ascertained for a few Fungi only. Wiesner found the minimum to be from 1.5° to
2° C. in the gonidia of Penicillium glaucum, the maximum 40° to 43° C., and the
optimum about 22” C.; the cardinal points are probably similarly situated in very many
Fungi in our latitudes. Thus Ustilage Carbo germinates according to Hoffmann at a
temperature of from +0.5 to 1° C,, Botrytis cinerea at +1. 6° C., Ustilago destruens
requires a temperature above +6° C, but continues to germinate at 38.75° C.;
I observed Cystopus candidus develope zoospores and their germ-tubes as weil
at +5 as at 25°C.

More exact observations will bring to light many variations in this respect in
species and individuals such as are found in other regions of the vegetable
kingdom. Aspergillus fumigatus, Fresen., which was carefully examined by Lichtheim?,
may be mentioned as a striking instance of this kind among the Fungi; in this
plant it was approximatively determined that the minimum did not fall much
below +15°C.

1 Sitzgsber. d. Wiener Acad. 67, I (1873).
? Berliner klinische Wochenschrift, 1882, Nr. 9.

350 DIVISION III.—MODE OF LIFE OF THE FUNGI,

Fungi which are in the habit of germinating in the digestive canal of warm-
blooded animals, the Mucorini, Piloboli, Ascoboli, and indeed also the Sordarieae
and Coprini, have an optimum corresponding, as might be expected, with the
temperature of the body of the animal. Brefeld! even gives the minimum as from 35”
to 40°C. in the case of one species of this group, which he does not determine
more nearly. He also gives from 35” to 40° C. as the minimum in the case of Cru-
cibulum vulgare, which is supposed to germinate regularly in the intestines of animals,
while Eidam ? has observed its germination at a temperature between 20° and 25°C.

The supply of oxygen, which must be regarded as necessary for general reasons,
has never been specially investigated in the germination of the Fungi. Its necessity
is shown when spores are sown in drops of liquid beneath a covering glass. The
spores germinate better the nearer they lie to the edge of the covering glass where
there is a free supply of air; they often do not germinate at all in the middle.

The necessity of a supply of water is evident in all cases and is intelligible.
It is plain from the swelling of the germinating spore and the formation of successively
growing vacuoles that the process of germination begins with absorption of water. It
depends on the species or the form of the spore whether pure water is necessary, or
whether the water must contain certain nutrient substances or whether germination
takes place both in water and in nutrient solutions.

The first category includes a number of strictly parasitic forms, the Perono-
sporeae especially and Uredineae, and also the Erysipheae, Polystigma rubrum and
species of Rhytisma. Many of the Lichen-fungi may also belong to it, but this is a
point which requires investigation. The spores especially of the two first groups
germinate best when they are not in but on drops of water or in an atmosphere
saturated with vapour, which no doubt supplies them with the requisite amount of
water in the shape of slight precipitations. Nutrient solutions may even hinder
germination. Observation shows that the normal processes in germination are
effected entirely at the expense and by the transference of the substances in the spore
(see sections LXXIX—LXXXIH).

The gonidia of Mucor stolonifer, Chaetocladium and most of the Mucorini
and the ascospores of Sclerotinia Fuckeliana are examples of the third category which
represents the other extreme. These Fungi emit at best only weak rudimentary
germ-tubes in pure water, and it is not certain that these are not due to small
admixtures of nutrient substances which entered the water with the spores. The
ascospores of the Sordarieae and the spores of the Coprini also belong to this list.
Their germ-tubes have been obtained hitherto only in nutrient solutions, and we have
no exact account of their behaviour in pure water, because it has but little practical
interest.

The spores of most Fungi belong to the second and intermediate category, with
an inclination to one or other extreme according to the species. Examples are seen in
the gonidia of Penicillium, Sclerotinia Fuckeliana, and other common forms of Moulds,
and in the spores of the Ustilagineae and Tremellineae, with respect to which the
reader should compare the statements in the sections of Chap. V which refer to them.

1 Schimmelpilze, IV, p. 20.
? In Cohn’s Beitr. z. Biol. II.

CHAPTER VI.—PHENOMENA OF GERMINATION. 351

In the cases in which a supply of nutrient substance is mecessary for
germination, the commencement of the process of germination implies a previous
commencement of a process of nutrition, which is only another way of expressing the
facts. Accordingly germination is attended by the permanent and constant increase
in the amount of protoplasm which was described on page 113. The germinating
spore behaves in the same way as a growing vegetative cell. The same thing
evidently takes place in the intermediate cases connected with this extreme. It has
yet to be enquired how far water only may be taken up from the solution in other
cases, for instance at the commencement of germination.

The nutrient substances suited for germination are in most cases of the same
kind as those adapted to the vegetation of each species. Yet there appear to be
exceptions to this rule. The spores of Ascobolus furfuraceus! which vegetates in the
faeces of herbivorous animals have only at present been made to germinate on the
mucous membrane of the stomach of living animals. They did not germinate in
water or in nutrient solutions or in juice obtained by artificial means from the
stomach of a pig, neither in the ordinary temperature of the room nor in that of the
animal body. It remains to enquire how far the germination depended on special material
qualities of the surface of the mucus membrane. I observed similar phenomena in the
case of Onygena corvina which vegetates normally on the feathers of birds of prey.
No result was obtained when spores were sown on microscopic slides with the variations
mentioned above; but there was a fine formation of compound sporophores of Ony-
gena on the hairs cast up by a white ow] which had been kept a long time in captivity
and which had received the spores of the Fungus with a mouse which it had eaten;
the Fungus developed on the hair from the mouse on which the spores had been
strewed and from no other. The development of Onygena came to an end indeed on
most of the hairs thus obtained, and a rich growth of Gymnoascus, not intentionally
sown, took its place, which perhaps drove out the Onygena. Further investigation
of this case is necessarily deferred.

The formation of the germ-tubes of Protomyces macrosporus has hitherto been
observed only on the epidermis of Aegopodium, not in nutrient solutions. It
remains to be seen whether this is a similar case to those which we have been
considering, or one where a particular nutrient substance is required for the process of
germination.

It appears from the facts which have now been enumerated, that the necessity
for the presence of nutrient matter in germination, as well as for certain temperatures
and for the changes not exactly ascertained which must take place during the state
of rest, are connected with analogous specific differences or adaptations in the plants
themselves. We can scarcely suppose that the necessity for a nutrient substance
depends simply on the guantity of reserve material present in the spore. This is
shown by the recorded observations on the ascospores of Sclerotinia Fuckeliana as com-
pared with the very similar spores of the nearly related Sclerotinia Sclerotiorum. The
latter germinate readily in pure water. On the other hand, it is obvious that the
spores which only need a supply of water for normal germination must be provided
also with the requisite quantity of reserve material.

_ There are still many spores of Fungi, entire groups of them, which have never been
observed to germinate. Putting the spermatia mentioned in the morphological portion

1 Janczewski in Bot. Ztg., 1871, p. 257.

352 DIVISION III.—MODE OF LIFE OF THE FUNGI,

of this work (page 240) altogether out of the question, we may quote here, as
examples only, the basidiospores of most Gastromycetes (Phalloideae, Lycoperdaceae,
Hymenogastreae), and the ascospores of Tuber, Elaphomyces, and allied genera,—organs
which in contrast with the more or less doubtful spermatia are quite certainly
homologous with allied forms which germinate readily. To these may be added
the zygospores of Mucor stolonifer, Brefeld’s Mortierella Rostafinskii. The germination
of Agaricus campestris also has never been certainly observed’. The number of cases
of this kind has gradually diminished, the more it was recognised that the conditions
of germination or adaptations might vary from one species to another and the more
these conditions were ascertained in particular cases. This must be considered in judging
of unsuccessful experiments in germination, and may lead us to expect success from
further investigations in cases where it has hitherto been wanting. On the other hand,
phenomena such as those pointed out on page 332 in connection with Sphaerobolus must
not be disregarded.

The sporocarps of Erysiphe which were closely studied by Wolff? show that in
germination as elsewhere adaptations may occur which deviate considerably from those
ordinary cases of adaptation on which our views are apt to be founded. These arrive
at maturity, that is, separate from the nutrient substratum with the termination
of the period of vegetation. At this time the asci are formed inside them and in
most species the spores also are formed in the asci, but in some (E. graminis, E.
Galeopsidis) no spores are yet formed. In this condition the sporocarp enters upon
its winter’s rest. When this is over and the sporocarp is placed in water, the spores
are formed and ripen in E. graminis and E. Galeopsidis, in other species, as E. communis,
they ripen only; then the spores are at once discharged from the sporocarp which
bursts by the swelling of its contents, and the spores germinate. In this case therefore
the mature sporacarp hibernates, provided, as minute investigation shows, with reserve
material for the subsequent formation of the spores, and the spores, even those which are
apparently and which were formerly supposed to be ripe before hibernation, do not really
mature and acquire the capacity for germination till after the winter rest is over. In
contrast to this proceeding most other homologous sporocarps form mature spores |
with the power of germination either without passing through a resting stage or before
they enter it, or else they become dormant before the formation of the asci when they
are in form like a sclerotium or xyloma. It is not yet ascertained whether there are
not species even of Erysiphe which dispense with a period of rest. Tulasne’s* account of
E. guttata seems to point in this direction.

CHAPTER VII. PHENOMENA OF VEGETATION.

1. GENERAL CONDITIONS AND PHENOMENA.

Section XCVII. Fungi resemble all other plants in the main features of
their organisation and material composition ; it may be assumed therefore beforehand,
and the assumption is confirmed by experience, that the most general conditions of
vegetation are the same in both classes, which may therefore in general terms be said
to be dependent in the same manner on light, heat, gravitation, and the chemical

1 See Nylander, Flora, 1863, p. 307.
? As cited on p. 294. See above, pages 76 and 202.
® Carpol. I.

CHAPTER VII.— PHENOMENA OF VEGETATION.— GENERAL CONDITIONS. 353

nature of their environment, while each individual according to its particular organ-
isation has a special reaction on the influence exercised by these agencies ?.

In judging of the phenomena which present themselves to our notice, it is at
least as necessary to consider the influence of temperature on the vegetation and
growth of Fungi as the temperatures of germination noticed above. In this relation
also plants are subject to fixed rules. Every vegetative (and fructificative) process has
certain limits of temperature and a fixed optimum in each species. In Wiesner’s
series of experiments cited above on page 349, all other conditions being the same, the
optimum in the growth of the mycelium of Penicillium glaucum was about 26° C., that
in the formation of gonidia, like that of germination, was about 22°C. Many Fungi
which are natives of our temperate zone probably exhibit the same relations to
temperature as Penicillium. That there are differences, however, between one species
and another is shown at once by the circumstance, that some Moulds make their
appearance spontaneously in closed places, ceferis paribus in the hottest time of the
year, and it may almost be said at no other time. I observed this for instance years
ago in the case of Aspergillus clavatus, Desm. According to Siebenmann’s? statements,
which, it is true, require further testing, Eurotium repens flourishes in a temperature of
from 10° to15° C., and disappears at 25°C.; the same is said to be the case with E. Asper-
gillus glaucus; A. albus and A. ochraceus do well at from 15° to 20°C., but suffer if the
temperature rises above 25°C. In A. niger, on the contrary, Raulin® found that the
optimum in the formation of mycelium and gonidia was ceteris paribus 34° C.; in
A. fumigatus Lichtheim * places it at from 37° to 40°C. These statements contain limits
which may at all events be turned to account. All but the two last are imperfect,
because they give no exact information as to the nature of the substratum and any
other forms which may have been growing with those observed.

Transgression of the limits of the temperatures of vegetation leads at first in the
Fungi, as in all plants, to rigidity whether arising from heat or cold, without destroying
life. There are of course individual and specific differences in the power of resisting
unfavourable influences, but it may be assumed that the higher limit of endurance in
most Fungi in a state of vegetation, as in other plants, is about 50° C., though it is
sometimes higher than this in a stage of rest when they contain little water, as is the
case with spores ; on the other hand daily experience tells us, that many growing Fungi
can stand a hard frost. The excessive power of resistance displayed by Saccharo-
myces has been already noticed at page 347.

The time also which is required for extreme temperatures to take effect is of
course to be considered in all cases.

Section XCVIII. Chemical analysis and an examination of the organisation of
Fungi teach us that they have the same need of food as other plants, and like them

1 On the observed effects of light on the growth of Fungi and on the phenomena of etiolation,
geotropism, heliotropism, hydrotropism, and thermotropism see Pfeffer's Physiologie and the
references there to other works. Also, Wortmann, in Bot. Ztg. 1881, p. 368 and 1883, p. 462, and Van
Tieghem in Bull. Soc. Bot. de France, Febr. 11, 1876, and in Ann.d.sc nat. ser. 6, IV, p. 364, also
in his Traité de Botanique, pp. 116, 301, and Molisch, in Bot. Ztg. 1883, p. 607.

2 Die Fadenpilze Aspergillus, &c. u. ihre Beziehungen zur Otomycosis, Wiesbaden, 1883, p. 24.

3 Ann. d. sc. nat. ser. 5, XI, p. 208. * As cited on page 349.

[4] Aa

354 DIVISION III.—MODE OF LIFE OF THE FUNGI.

they can only take up their food in a fluid or gaseous condition. The general
difference between the process of nutrition in the Fungi and in plants which contain
chlorophyll and similar substances consists in their inability from want of chloro-
phyll to decompose carbon dioxide. They must obtain their carbon by taking
up organic carbon-compounds previously formed in some other bodies, as is the
case with all organisms or parts of organisms which do not contain chlorophyll.

According to experiments with Moulds and Saccharomycetes in artificial nutrient
solutions, the nitrogen is taken up and disposed of to the benefit of the plant in the
form of inorganic compounds, provided the carbon is obtained as some organic
compound such as sugar ; Moulds like Penicillium, Mucor racemosus, and Aspergillus
niger (Pasteur, Fitz, Raulin) take up nitrogen from ammonia-compounds as well as
from nitrates, while ammonia is a good and nitric-acid a very indifferent source of
nitrogen ‘for the Veast-saccharomycetes (Mayer, Nägeli)’. Moreover the need
of carbon as well as that of nitrogen may be supplied in the same Fungi by means of
organic compounds which they are able to take up; some of these supply more
nutrition than others, and some supply none at all. According to Nageli almost all
compounds of carbon afford nourishment with the addition of oxygen, provided they
are soluble in water and not too poisonous. Urea, formic acid, oxalic acid and oxamide
(Nageli) besides CO, and cyanogen are exceptions to this rule. A large number
of compounds may serve as sources of nitrogen, if they are in a soluble state or can
be made soluble by the Fungus. Free nitrogen and cyanogen cannot by themselves
supply nourishment. Some compounds containing nitrogen may serve at the same
time as sources of nitrogen and of carbon, others, as oxamide and urea, only as
sources of nitrogen. According to Nägeli, Penicillium grows best in a solution of
proteid (peptone) and sugar ; then in the following solutions arranged in descendihg
order according to their nutritive capabilities: 1. leucine and sugar; 2. ammonium
tartrate or sal-ammoniac and sugar; 3. proteid (peptone); 4. leucine; 5. ammonium
tartrate, ammonium succinate, asparagin; 6. ammonium acetate.

As regards the constituents of the ash the requirements of the Fungi are
essentially the same as those of other plants, but with this limitation according
to Nägeli ?, that Fungi are comparatively less particular in their selection.

“Fhe amount of available food-material in the substratum is not the only point of
importance; its chemical nature also has to be considered, as was intimated
above in the account of the conditions required for germination. Dutrochet ®
discovered some time since that the development of Moulds was affected by the acid
or alkaline reaction of the fluids in which they grew, and more recent investiga-
tions, dating from the year 1860, have shown the existence of important specific
differences in this respect in the Fungi. The common Moulds flourish in nutrient
solutions which are more or less acid; they do not grow so well or refuse to grow
in neutral or slightly alkaline fluids. ‘The Schizomycetes behave as a rule in the
reverse way (vid. infra, Chap. XI). A trace of acid is sufficient to retard the develop-

1 A review of the subject and its literature will be found in Pfeffer, Physiol. I, 242. See also
Nägeli, Ernährung d. niederen Pilze (Untersuch. &c. 1882, 1, and Sitzgsber. d. Münchener Acad.
Juli, 1879), and Raulin in Ann. d. sc. nat. ser. 5, XI (1869), 220.

® Untersuchungen, 1882. ® Ann. d. sc. nat. ser. 2, I, p. 30.

CHAPTER VII.— PHENOMENA OF VEGETATION.—GENERAL CONDITIONS. 355

ment of some Basidiomycetes'. Shades of difference varying from one species to
another are found within these average limits.

Respect must also be had to certain physical conditions in the food-material as
well as to its chemical qualities. This was shown by the fact that the plants thrive
differently according to the difference in concentration of the same good nutrient
solutions” Dependence on other things, such as cohesion and conditions of
imbibition, may also require to be taken into account in many cases, especially among
parasitic Fungi.

It follows of course from universal physiological laws that a process of respiration
accompanies that of nutrition in the vegetating Fungus-cell, as free exhalation of
‚oxygen or as intramolecular respiration.

Since Fungi take up food-material from the substratum, and cause fermentations
or more or less perfect combustion of the substratum by their processes of respiration,
they must necessarily produce chemical changes in the organic bodies in which they
live; they also give rise in numerous cases to unorganised ferments with specific
modes of operation. Species of Saccharomyces, Penicillium, and Aspergillus niger—
not however Mucorini which excite alcoholic fermentation in a solution of grape-
sugar *—produce invertin which splits cane-sugar into dextrose and laevulose.
The mycelial hyphae of many Fungi and the germ-tubes of many parasites
on other plants grow in thick even lignified or cuticularised cellulose-membranes
and in starch-granules, and make passages through the parts which may cause,
as Hartig has so well shown‘, wide-spread destruction in the woody tissue.
The lignin first of all in the walls of the tracheides in pine-wood, then the
cellulose, and finally the middle lamella is dissolved according to Hartig by Trametes
radiciperda and T. Pini. Similar effects are produced by other wood-destroying
Hymenomycetes. The hyphae of Cordyceps spread widely in the thick chitinous
investment of the larvae of insects. These facts distinctly prove the secretion of
solvents, and we can scarcely conceive of these in any other form than that of
ferments.

We have become acquainted during the last twenty or thirty years with a very
large and varied series of phenomena connected with Fungi and their substrata and
with a corresponding number of specific adaptations between them. It will be
necessary now to take a somewhat closer view of these adaptations and therefore of the
habits of the Fungi as they have been observed and their effects on the bodies which
they inhabit. With respect to special chemical questions the reader is referred to
treatises on the chemistry of fermentation, and to pathological works for some
questions which arise on the subject of the aetiology of diseases.

1 Brefeld, Schimmelpilze, IV, p. 7.

2 See especially Raulin, as cited on last page.

3 See Pfeffer, Phys. I, 282. Bechamp, in Comptes rendus, 36 (1833), p-44. Gayon in Comptes
rendus, 86, p. 52.

4 Hartig, Die Zersetzungserscheinungen d. Holzes, Berlin, 1878, and Lehrb. d. Baumkrankheiten,
p.-78. Among the earlier literature may be cited: Unger in Bot. Ztg. 1847. Wiesner, in Sitzgsber.
d. Wiener Acad. Bd. 49. Schacht, in Monatsber. d. Berl. Acad. 1854, and Lehrb. d. Anat. I, 160,
and in Pringsheim’s Jahrb. III, 442, &c.

Aa2

356 A DIVISION III. —MODE OF LIFE OF THE FUNGI.

2. NUTRITIVE ADAPTATION.

Section XCIX. Fungi have long been divided into two main sections founded
on their nutritive adaptation Those which constitute the first category feed on living
organisms whether plants or animals, and are termed parasites. Their relationship
with their hosts is that of a common life, a symdzosis. The others inhabit decaying
bodies and feed on dead organic substances, and have been named therefore since 1866
saprophytes. The two kinds of adaptation are sharply distinguished from one another
till we come to cases in which it may be doubtful whether a body should be said to be
alive or dead, but with these we are not further concerned; both are distributed
unequally amongst the different species, and are developed in varying degrees in
different individuals with many intermediate gradations. The extreme cases and the
first to be distinguished are species of purely and strictly saprophytic and species of
strictly parasitic mode of life. Others lie between these two extremes ; there may be
firstly species which both can and do normally go through the whole course of their
development as saprophytes, but which have also the power of going through their
course of development wholly or in part as parasites ; these may be called with Van
Tieghem facultative parastles. Secondly, species which, as far as we know, do as a
rule go through the whole course of their development as parasites, but at the same
time are able, at least in certain stages, to vegetate as saprophytes: these may be
termed facullative saprophytes. As far as we fully and certainly know, the parasitic
mode of life is always indispensable to the complete development of this second kind.
Keeping in view the latter circumstance we obtain the following grouping according to
the life-condition: 1. Pure saprophytes. 2. Facultative parasites. 3. Obligate
parasites, that is, species to which a parasitic life is indispensable for the attainment
of their full development. The latter are again divided into (a) strictly obligate
parasites, that is, species which, as far as we know, live only as parasites, and (b)
facultative saprophytes. Most species in category 2 may be able to attain their full
development in both modes of life. It is at present uncertain whether there are
transitional forms between them and 3 (b), parasitism being the rule in some species,
but the full development being possible in exceptional cases in a saprophytic mode of
life ; the many gradations between them of other kinds make it not improbable.

In presence of these gradations the foregoing division can only be a frame, such
as is necessary for obtaining a clear survey of the phenomena, and it should be
distinctly observed that it has in view the ascertained adaptations and arrangements
which hold good in the natural, and, as we are accustomed to say,, the spontaneous

course of things. There may be possibilities of existence in a species which
transcend these adaptations. Artificial conditions may in some cases be established
which may result, for example, in the development of a spontaneously and strictly
parasitic Fungus in a way not parasitic, just as it is possible to rear normal bean or
maize-plants by water-culture. We can conceive such a possibility in every case,
even in much more difficult cases than any which occur in this work, such for instance
as those of trichinae and tape-worms. It must also be allowed that plants cultivated
under artificial conditions of such a kind may be of the greatest help to the under-
standing of the phenomena. How far a state of things produced for the purpose of

CHAPTER VII.—PHENOMENA OF VEGETATION.—SAPROPHFTES. 357

experiment does actually occur among the natural conditions is a distinct question
requiring a special enquiry for its determination, and the observed fact is as little
altered by any experimental result in the present case, as in the instance referred to
above of land-plants which thrive when grown in water.

3. SAPROPHYTES.

Section C. By far the larger part of the Fungi, according to our present
knowledge, are saprophytes; our fifth chapter has already shown that this is the
case.

We at present have onlyan imperfect acquaintance with life-conditions and adapta-
tions in these species, yet there must be a great variety of them in all the many cases
described in the books, in which a particular species of Fungus is always actually
found on a distinct, and, as it may be termed, a specific substratum. Indications of
this fact, to which attention has been already called on page 351, are afforded by the
Fungi which grow on the dejecta of warm-blooded animals, dung, feathers, &c.

The spores of these species, as was first shown by Coemans? in the case of
Pilobolus, easily find their way from their regular places of origin to the food of the
animal, are provided with the necessary conditions for germination in the intestinal
canal, and complete the development which they have commenced there on or in the
voided dejecta. Experiments in cultivation such as may be carried out without
difficulty show that other methods beside this one are not excluded, at least in the
case of many species which live on dung (Mucor, Pilobolus, Sordaria, and some
species of Coprinus).

The observations of Pasteur? and E. Hansen* have brought to light some
peculiar arrangements in the life of the Saccharomycetes which excite alcoholic
fermentation when growing spontaneously, though these arrangements are not yet
quite intelligible. According tothe careful investigations of the latter writer Saccharo-
myces apiculatus appears in the open air on garden fruits containing sugar as soon as
they are ripe, finding nourishment and growing on them, especially if the outer rind is
broken. It very rarely or never occurs on the fruit before it is ripe, and if it has
shown itself on early-ripening fruits, such as currants, gooseberries, or cherries, it is
wanting on others which ripen later, plums and grapes for instance, as long as they
are still green. In the interval between two periods of ripening of the fruit, even in
winter, it is found capable of development in the soil beneath the plants whose ripe
fruit it attacks, and very rarely in any other place. Distinct spores are not known in
this species, only the vegetative cells produced by sprouting. The actual life-history
of the plant is therefore very simple ; it is easy to conceive how it finds its way with or
from the ripe fruit by the aid of wind or rain to the ground and is carried back with
dust from the ground to the fruits, and its living through the winter in the ground is
not at all surprising; but it has still to be explained why it is so rarely or never found
on green fruit or in some other place. Pasteur* had shown before that cells of

1 Monogr. d. Pilobolus. See before on page 158.

3 Etudes sur la biere, especially at p. 155.

3 Meddelelser fra Carlsberg Laboratoriet, I, Résumé frangais, p. 159.
* Etudes sur la biere.

358 DIVISION III..—MODE OF LIFE OF THE FUNGI.

Saccharomyces which excite fermentation, but the forms or species of which he does
not determine, are found in abundance at harvest time on grapes and on their stalks,
while they are rarely or never found at a later time on grapes which have remained
through the winter and on young grapes in summer; this means that those cells which
may happen to have survived have at least become incapable of development.

Few saprophytic Fungi are known to be specific ferment-organisms, if we judge
of them by their effect on the substratum. Several species of Saccharomyces are the
Yeast-fungi of alcoholic fermentation, and near them come species of Mucor which
produce a similar kind of fermentation. The power of producing fermentation is a
specific peculiarity, as has already been pointed out on page 271, and not confined to
any particular growth-form, as that of the Sprouting Fungi for example. It is wanting
among the Saccharomycetes in the flowers of wine, Saccharomyces Mycoderma or
mesentericus, and perhaps in some others; it varies in the forms which excite fermen-
tation according to the species, all other conditions being the same. Of the Mucorini,
Mucor racemosus, M. circinelloides, and M. spinosus cause a tolerably active fermen-
tation in the sugar, while the activity of M. Mucedo is small, and that of M. stolonifer
is scarcely greater. Van Tieghem* showed that the mycelium of Penicillium and of
Aspergillus niger when growing in sclution of tannin breaks up the tannin into
gallic acid and glycose.

The ferment-secretions have already been noticed on page 355. It is almost
certain ‘that further investigations will show the existence of fermenting power in other
saprophytic Fungi.

It is known that the final result of the process of vegetation in most of the
saprophytes which have been examined is a combustion of the organic substratum.
Penicillium also and Aspergillus niger cause combustion of the tannin when they
vegetate on the surface of the solution with an unlimited supply of oxygen.

4. PARASITES.

Section CI. We have little exact knowledge of the chemico-physiological pro-
cesses in the life of the parasitic Fungi, because the symbiotic relation puts great
complications and difficulties in the way of their precise investigation.

We encounter on the other hand in these Fungi a very long and varied series of
phenomena of one-sided or reciprocal adaptation between the parasite and the.
living organism on which it feeds, and some of these phenomena are of a very
obvious character. In contemplating them we have to set out from the following
general considerations.

The plant or animal on which a parasite lives is termed its ost or feeder.
Every parasite species lives on certain host-species, and the limits within which it can
choose its host are different in different species. Some parasites have never been ob-
served on more than a single host, Peronospora Radii for example on Pyrethrum ino-
dorum, Uromyces tuberculatus on Euphorbia exigua; so Cystopus Portulacae, Rhytisma
Andromedae, Triphragmium Ulmariae and T. echinatum, and many other species that

1 Brefeld, Ueber Gährung, as cited on page 188. —Gayon in Comptes rendus, 86 (1878), p. 52,
and in Ann. Chim. et. Phys. XIV (1878), p. 258.
? Ann. d. sc, nat. ser. 5, VIII (1867), p. 210.

CHAPTER VII.—PHENOMENA OF VEGETATION. —PARASITES. 359

are parasitic on plants; of parasites on animals Laboulbenia Baeri is found only on
house-flies. Very many kinds thrive on a larger or smaller circle of nearly allied
species which serve them as hosts; among these are many Uredineae, Ustilagineae,
and Peronosporeae, Epichloe typhina which lives on the Gramineae and Claviceps
purpurea; Cordyceps militaris grows on insects of various orders, especially
Lepidoptera ; C. cinerea, as far as is known, only on species of Carabus, other kinds
only on wasps, and so on. Some kinds make specific exceptions within the immediate
circle. of affinity of their host, or they occasionally travel beyond that circle; I
succeeded for instance in transferring Puccinia suaveolens, which usually lives on
Cirsium arvense and Centaurea Cyanus, to Taraxacum but not to Tragopogon;
Phytophthora infestans, which is usually confined to the Solanaceae, is found excep--
tionally on the Scrophularineae (Anthocercis viscosa, Schizanthus Grahami), Perono-
spora parasitica of the Cruciferae on Reseda luteola.

This exceptional power of accommodation forms the passage to the third category,
that is, to parasites which attack plants and animals of very different cycles of affinity
either without any distinction whatever or with a preference for certain species.
Examples of parasites of this kind living on plants are species of Erysiphe, as
E. guttata which lives on the leaves of Corylus, Carpinus, Fagus, Betula, Fraxinus, and
Crataegus, Phytophthora omnivora which attacks Fagus, Sempervivum, the Oenothereae
and other plants, but not Solanum tuberosum’, and Sclerotinia Sclerotiorum, which
can penetrate as a parasite into the most diverse juicy parts of plants. Of cases of
parasites on warm-blooded animals may be mentioned Lichtheim’s Mucor rhizopodi-
formis, one of the pathogenous Moulds which will not develope on the dog, but grows
vigorously in the rabbit; Aspergillus fumigatus attacks both of these animals; no
others have been tried. For further examples the reader is referred to descriptive and
pathological treatises.

These facts and gradations would lead us to expect that there must also be
differences in the aggressive behaviour of a parasite to the different varieties and in-
dividuals of a host; or, to express the matter in the converse way, in the predisposction
of the individuals for the attacks of the parasite. In this direction also there are all
possible gradations. On the one hand there are parasites which, as far as we know,
show no preferences of the kind, for instance all the strictly parasitic species of the
genus Peronospora and of the group of the Uredineae in which this point has been
examined. The other extreme is represented by the Saprolegnieae for example,
which attack fishes, and by the Sclerotinieae and Pythieae, which as facultative
parasites attack Phanerogams. These will be discussed at greater length in a suc-
ceeding page (see p. 380). The physiological reason for these predispositions cannot
in most cases be exactly stated; but it may be said in general terms to lie in the
material composition of the host, and therefore to be indirectly dependent on the
nature of its food. In the case of the Pythieae, for example, it is easy to see that the
host displays degrees of susceptibility or power of resistance in presence of the parasite
proportioned to the amount of water which it contains. It must on the whole be

-2 Bot. Ztg. 1881, p. 595.

2 On the disposition of plants see Sorauer, Landw. Versuchsstationen, XXV (1880), p. 327, and
the discussion in Bot. Ztg. 1882, pp. 711 and 818. The questions of disposition and immunity in the
case of diseases of animals caused by parasites are fully discussed in medical literature.

360 DIVISION III.—-MODE OF LIFE OF THE FUNGI,

conceded that a predisposition for the attäck of a parasite may in some cases be a
sickly one, especially if there are deviations at the same time from the condition
which we are accustomed from experience to consider the healthy condition in the
particular species. But it is also evident, on the other hand, that the predisposition to
the attacks of parasites does not always show a sickly condition of the plant, not for
instance when there is no parasite present. The real state of things must be investi-
gated and determined case by case. :

It was shown by many examples in the morphological portion of this work, that
the parasite is either an endophyle and lives inside the organs or even the cells of the
host, or is to a great extent an efzphy/e on its outer surface. A purely epiphytic mode
of life, in which the parasite rests on or is attached to the outer surface of the host, is
comparatively rare if we disregard the case of the Lichen-fungi to be described in
section CXV ; the Laboulbenieae (page 263) and Melanospora parasitica ' and perhaps
also those Chytridieae which are said only to rest on their host may be mentioned
as examples of this kind. Other epiphytes, as Erysiphe, Piptocephalis, and Syn-
cephalis, enter the interior of the host at least by the haustoria which they send into
it. Chaetocladium adhering to its host and with its tubes in open communication
with those of the Mucor which serves as its host does not strictly come into either of
the two categories (see on page 20). Either designation may be applied to the
Fungi which spread in the deric tissues of the higher animals.

After these preliminary remarks we may proceed to consider the phenomena
of adaptation above indicated under three general heads: 1. The attack of the
parasite on its host, that is, the first beginning of the occupation. 2. The course
taken after occupation by the further growth of the parasite. 3. The reactions of
the host after tts occupation and the results of the reciprocal action of the two symbionts.
It is owing to the nature of the subject-matter, that though the three questions are
kept theoretically distinct from one another, the answers to them must necessarily
travel out of the domain of one question into that of another, and especially from the
second to the third.

Section CII. The parasitic Fungus attacks its host by means of its spores,
or of the germ-tubes emitted by the spores, or of the hyphae developed from the
germ-tubes.

The first case, in which the first attack is made by the spore before germination,
is-confined to a comparatively small number of epiphytic species, which will be
noticed again in another connection at the conclusion of the paragraph, and to certain
facultatively parasitic and facultatively endophytic species of Moulds, namely, the
pathogenous Aspergilli and Mucor-forms (M. rhizopodiformis and M. corymbifer)
which have been studied by Lichtheim®. These Fungi are developed in the internal
érgans of warm-blooded animals, when their spores find their way into the blood-
passages and are carried by the blood to suitable spots; wounded places therefore,
though of very small extent, are always in the natural course of things the parts where
the endophytically developed Fungus first makes its attack. These forms are actually
known as true endophytes only from artificial injecfion usually of a large number of

' O. Kihlman, as cited on page 262.
-? Ascited on page 349, and in Zeitschr. f. klin. Medicin, VII, Heft 2.

CHAPTER VII. —PHENOMENA OF VEGETATION.—PARASITES. 361

spores; they appear in nature rather as epiphytic growths on the walls of cavities in
the bodies of animals which are easily accessible from without, such as the passages of
the ear and the bronchi.

In most cases the spore of the parasite begins the emission of a germ-tube
independently of the host, either after simple absorption of water or by appropriation
at the same time of food-material produced outside the host. If the tubes or the
hyphae which proceed from them then come into contact with the host, they fasten
upon it in the way peculiar to each species. The most common case of the kind is
when the spore finds its way by some mode of dissemination or other to the surface
of the body of the plant or animal, and puts out germ-tubes which penetrate into the
body. Parasites which, like Ancylistes Closterii and Polyphagus Euglaenae, attack
unicellular organisms living in societies, send out mycelial branches from the individual
first attacked, and these can fasten upon fresh individuals and by degrees on entire
aggregates of the host-cells. Some
facultative parasites of higher or-
ganisms, Sclerotinia for example,
Agaricus melleus and others of
R. Hartig’s tree-destroying species,
behave in the same manner, since
any of the hyphae or mycelial
strands are able to make their way
into new individual hosts.

The act of penetration is
accomplished in two ways; the Papaya esate
germ-tube or branch of the myce- [2 Pp which have g i d on the epi is of Faba vulgaris, the

germ-tube penetratinginto astoma. c germ-tube which has passed through the

er H =} 7. 7 stoma sinto the parenchyma of a leaf of Fada and there ramified: cis a portion
lium either grows into the Interior of a transverse section through a leaf of Fada, the cell-wall of the spore and

of the host through a natural the piece of the germ-tube which is outside the leaf not being shown. Magn.
195 times

FIG. 163. Uromyces app 7 a

opening in it, or it pierces /hrough
the firm membranes of the surface of the body of the host. The one or the other
mode is adopted according to the species and the kind of spore; it is seldom that both
occur promiscuously.

_ Many examples of the first kind are supplied by those endophytic parasites on
plants, in which the germ-tubes emier the host by the stomala only. All the uredo-
spores and aecidiospores of the Uredineae for instance germinate on the moist
epidermis of phanerogamous plants. The germ-tube grows in a curve on the surface
of the epidermis, and when its tip reaches a stoma it descends into it, usually after it
has first become vesicularly swollen outside the stoma, and then passes on into the
air-space which lies beneath it. Here it increases rapidly in size and receives the
entire protoplasm of the germ-tube, while the rest of the germ-tube outside the spore-
membrane dies away. The extremity of the tube which has thus penetrated into the
host can now put forth branches which develope into mycelial hyphae (Fig. 163).
These germ-tubes enter tlfe stomata of any phanerogam, but only develope further in
the species which is the proper host of the particular parasite ; they wither away in all
other species in the subepidermal air-space. The short germ-tubes from the sporidia
of Leptopuccinia Dianthi, DC. proceed in a similar manner. If a sporidium of this
plant germinates in the neighbourhood of a stoma of the host, its germ-tube grows

362 DIVISION III.-—MODE OF LIFE OF THE FUNGI.

towards it, enters it and developes into a mycelium. If germination, which ‘occurs
readily everywhere in a damp atmosphere, takes place on some other substance, the
tubes grow irregularly in every direction and perish after a short increase in length.
The entry through the stomata has been observed also in species of Entyloma? and
Kuhn’s Polydesmus exitiosus®. Further instances will be found in pathological
literature.

Among endophytic parasites on animals I mention here the germ-tubes of the
aerial gonidia of Cordyceps militaris (‘Isaria farinosa’), which I only saw enter the
stigmata of caterpillars on which they had developed from the germinating spores? ;
but this observation requires to be revised.

The second case in which the germ-tubes or hyphae pierce through the firm
membranes of the uninjured host is probably the more common. It is of course the
form which occurs in all endophytes on unicellular organisms. Examples of it are
seen in the case of parasites on higher plants in the germ-tubes from the sporidia of
the Uredineae, excepting always Leptopuccinia Dianthi just mentioned, and in those
of most of the Peronosporeae and Ustilagineae*; Polystigma rubrum ° together with
many other Pyrenomycetes and Discomycetes, Claviceps also and the facultatively
parasitic Sclerotinieae (see section CVIII) may be added to the list. It is to be
particularly observed that the germ-tubes of these parasites on higher plants never
penetrate into the host by a stoma. Even if the spore lies on or near a stoma, the
germ-tube either pierces through a guard-cell, or crosses the cleft as it grows and
pierces the wall of an adjacent cell.

The germ-tubes of most of the insect-killing Cordyceps, Botrytis Bassii, and the
Entomophthoreae belong to this class; their tubes pierce through the chitinous skin
of the body of the host, and may begin to ramify in the substance of the thick
chitinous skin of the larger caterpillars.

Some parasites on plants show both modes of proceeding, for the same germ-
tubes may penetrate through the stomata and through the membrane of epidermal
cells; this is the case in Peronospora parasitica, Phytophthora infestans, and Exoba-
sidium Vaccinii*®; species also of the mode of life of Sclerotinieae can enter the host
by the stomata.

-Finally, there are a certain number of parasites whose germ-tubes and hyphae
penetrate into woody plants, not through uninjured surfaces, but where some wound
has been received, and from thence make their way into open spaces, such as injured
vessels (Nectria cinnabarina), or pierce through the cell-membranes. This is the case
with most of the tree-destroying Hymenomycetes studied by Hartig, with Peziza Will-
kommii and the species of Nectria which are parasites on trees. See section CVIII.

From this series of phenomena which constitutes the general rule deviations occur,
in two directions, but the deviations are connected with the rule by intermediate forms,

One of these deviations is found chiefly in endophytes which vegetate intracellu-

1 Bot. Ztg. 1874, pp, 93, 103.
? Krankheiten d. Culturgewächse, p. 152.

® Bot. Ztg. 1869, p. 590.

+ Wolff, as cited on page 185.—Kiihn, i in en d. Naturf. Ges. Halle, 24 Jan. 1876.
5 Fisch, in Bot. Ztg. 1882, p. 851. .---
6 Woronin, as cited on page 341.

CHAPTER VII. -—PHENOMENA OF VEGETATION,— PARASITES. 363

larly, and consists in extreme cases in this, that germination does not take place
independently of the host, but only when the spore capable of germination has
reached the surface of the proper host. When it has done this it at once puts out a
germ-tube at the point of contact which penetrates directly through the membrane,
otherwise it perishes without germinating. This is the history of many Chytridieae,
Synchytrium especially, which are entirely or partially intracellular in their vegeta-
tion, of Completoria’ also, and, as it appears, of Protomyces macrosporus. This
mode of penetration is also the normal one in some Chytridieae and Pythieae, though
they are able also to put out small short-lived germ-tubes without contact with the
surface of the host. A quite peculiar mode of proceeding, but approaching the
above, has been observed in the swarm-spores of Cystopus and Peronospora nivea
(Umbelliferarum) ; these spores put out germ-tubes in water which soon die away ;
in drops of water on the surface of their host they come to rest usually on or close
to the stomata of the latter and send their germ-tubes into them and then proceed
with their further development.

The other deviation from the general rule is observed in epiphytic parasites on
plants, which continue their chief growth outside the host during the whole of their
life, but send haustoria into its cells. Here the spores form germ-tubes independently
of the host, but where the tubes are in contact with a cell of the host, they send out
peculiarly shaped branches, which pierce through the wall of the cell and develope
into haustoria. In the Mucorini, which. are more or less facultatively epiphytic
(Piptocephalis, Syncephalis, &c.), a copious formation of mycelium and gonidia may
take place independently of the host if sufficient food is supplied to the plant. The
germ-tubes of the Erysipheae’, after a short increase in length, send a haustorium at
once into an epidermal cell of the host and develope on the food thus supplied to
them from it into mycelial hyphae, which successively form new haustoria similar to
the first, If the young germ-tube does not encounter the epidermis of a suitable host
it dies after a slight elongation.

When the germ-tube penetrates through a membrane, which usually happens
after it has grown for a short time in some other direction, its extremity bends round
towards the wall which is to be pierced, presses upon it and then grows transversely
or obliquely through it. In doing this it may maintain nearly the same breadth
in the perforated membrane as it had outside it, or it may be considerably
narrowed and contracted. But in certain cases, as for example in the sporidia of the
Uredineae, the portion of the tube which passes through the outer wall of the
epidermal cell is a very slender process, usually appearing only like a simple line even.
when highly magnified; as soon as this process has entered the cavity of the cell its
tip swells at first into a roundish and then into an elongated tube-like vesicle, and the
entire protoplasmic content of the spore streams into it; the spore itself and the
portion of the germ-tube which is outside the epidermis of the host are seen to be
filled only with a watery fluid and soon disappear. The filiform process also which
passes through the cell-wall then becomes indistinguishable, and the opening which
it produced in the wall appears to become closed up again; in a short time after the

1 Leitgeb as cited on page 160.
? De Bary, Beitr., and Wolff, Beitr., as cited on pages 261, 262. See also Fig. 6.

364 DIVISION III.—-MODE OF LIFE OF THE FUNGI.

perforation of the-wallevery trace ofthe proceeding has disappeared with the exception
of a small projection which attaches the tube within the cell to the place of entrance.
The tube now grows and ramifies inside the epidermal cell, and ultimately pierces
through the inner wall of the cell and developes a mycelium in the tissue Dean it
(Fig. 164).

The majority of the intracellular Chytridieae, especially the Synchytrieae, show
the same extremely slender perforating process, the same transference of the protoplasm
of the spore, and the same ultimate disappearance of the wall of the empty spore and
the perforating process.

In some species the penetration begins with an indentation in the membrane,
which must be accompanied with a corresponding local extension of the surface ; the
indentation forms a sheath of
a certain depth round the
tube, and is subsequently
pierced at the apex, showing
sometimes characteristic struc-
tural peculiarities. This is the
process in the case of Leitgeb’s
Completoria (see page 166),
Peronospora Radii and some
other species.

The above phenomena of
penetration on the part of
germ-tubes and haustoria take
place only in the membranes
of the host which happen to
be suitable to the parasite.
The germ-tubes when placed

FIG. 164. a Uromyces appendicul Sporidia inating on the epid x é
of the stem of Fava vu/garis, Mch.; the germ- ‚tube of one sporidium x has pene- on other species usually perish
trated into a cell of the epidermi and grown 5b Ph. hth infes-

tans; zoospore germinating and germ-tube penetrating into an epidermal cell (ut without penetrating into the
through transversely) of the stem of a potato. The preparation made seventeen
- hours after the dissemination of the spores. Magn. 390 times. cells. I have only once ob-
served an exception to this
rule; in this case the germ-tubes of Peronospora pygmaea, Ung. which lives on’
species of Anemone penetrated into the epidermal cells of Ficaria ranunculoides,
but died away there at once. The thickness or other structural characters of the
membranes of the host, which vary at different ages and in different individuals,
are in most cases of little moment, though young and delicate membranes are more
easily and more rapidly pierced than those which are strongly thickened. In certain
cases, however, perforation is possible only in certain states of development of
the membranes of the host, and these states have some relation to the age. The
Synchytrieae for example only penetrate into the epidermal cells of young leaves of
their host which are not fully unfolded; the sporidial germ-tubes of Endophyllum
Euphorbiae only into the epidermal cells of the young foliage of Euphorbia amyg-
daloides which are formed in the same summer with themselves, not into the leaves
of the previous year which have gone through the winter; and many Ustilagineae
only into parts of young.germinating host-plants.

CHAPTER VIT.—PHENOMENA OF VEGETATION.—PARASITES. 365

In some endophytes, Phytophthora omnivora', Tuburcinia Trientalis*, Proto-
myces macrosporus*, the entrance of the germ-tube of the parasite into the cells of
the host is more narrowly localised within the limits assigned above. While most
perforating endophytes make their way into the interior of the cells of the host at any
spot on their outer surface, the three Fungi above named make their entrance at the
outer edge of the side wall which divides two epidermal cells, and then grow on in
the middle lamella of this wall, splitting it in two and so pressing transversely or obliquely
through the epidermis; ultimately they produce both an intracellular and an
intercellular mycelium. This is at least the prevailing mode of penetration in these
species; perforation of the outer wall and lumen of an epidermal cell occurs
exceptionally in Phytophthora.

“In some of the purely epiphytic Fungi which do not penetrate into the host,
some for example of the Chytridieae* and the Laboulbenieae, the spores when
conveyed by some method of dissemination adhere simply to the surface of the host,
which is large in comparison to the parasite. The Lichen-fungi which live on small
and usually unicellular Algae put out germ-tubes which embrace the cells of the host,
as will be described in section CXV, when they encounter them in their elongation.
It has never been observed that the direction of this growth is influenced by the host
before contact.

Kihlman 5 has recently observed a very remarkable arrangement for fastening on
the host in the case of Melanospora parasitica, which is epiphytic on species of Isaria.
The almost cylindrical brown-walled spore, which is 5-6 a in length, germinates by
the emission of a germ-tube at each extremity, the tubes, whether grown in water or
in nutrient solutions, being scarcely longer than the transverse diameter of the spore.
If the spore lies against or on a hypha of Isaria, which is most frequently the case in
a state of nature, the germ-tube becomes firmly attached to the hypha of the host and
then developes into a mycelium. If the germ-tube comes into contact with an older
hypha of Melanospora, the membrane which separates them is dissolved and they
coalesce with one another. But if a germinating spore lies at some distance from a
growing hypha of Isaria, and it is not difficult to procure this in plants grown
on a microscopic slide, the direction of its growth in length is deflected towards
the spore till it comes in contact with the germ-tube, which then unites with it
and begins to develope. The greatest distance at which the germinating spore can
influence the direction of growth of the hypha is from four to five times the length of
the spore. ,

The physiological analysis and explanation of all these phenomena of
aggression, adhesion, and penetration through openings and membranes has yet to be
undertaken. We can here only notice briefly some of the chief points to be
considered.

The facts which have been stated above with regard to the perforation show, on
the one hand, distinct effects produced by the germ of the parasite on the host. The

U R. Hartig, Arbeiten d. forstbot. Instit. München, I.
? Woronin, as cited on page 185.

® Wolff in Bot. Ztg. 1874.

* See above, p. 171.

5 As cited on page 262.

366 DIVISION III.-—MODE OF LIFE OF THE FUNGI.

germ-tube causes a solution of continuity in the membrane which is being perforated
in the line of the perforation. Where the perforation is a hole which is permanently
fitted by the tube, as for instance in the chitinous skin of insects and in many
plant-cell-membranes, it is natural to suppose that the hole is caused by partial
dissolution of the membrane, and that this dissolution is the result of a fermentation
which proceeds from the Fungus (see page 355). The case is somewhat different
-where, as in the perforating germs of Uredineae and Synchytrieae, the holes soon
close up again. Here it may at least be asked, whether the perforating process from
the tube or spore ailached to the epidermis of the host does not split the membrane
by purely mechanical means, much in the same way as a sharp needle divides the
plate of caoutchouc which is pierced by it, and whether the small split does not close
up again purely in consequence of the elasticity of the membrane, as is the case in the
plate of caoutchouc after the needle is withdrawn, when the turgescence in the
perforating process sinks to nothing in consequence of the growth of the germ-tube.
The deflection of Isaria by Melanospora can only be explained by assuming that
some substance is secreted by the germinating spore which exercises a specific
attraction on the growing hyphae of Isaria.

_ On the other hand, the effects produced by the host on the parasite which is
germinating or about to germinate are more varied than those of the parasite on its
host, and a greater number of physiological questions are connected with them. We
do not know the cause why germ-tubes penetrate through stomata, why some spores
attach themselves to stomata, others to the surfaces of membranes, why the hyphae of
the Lichen-fungi clasp the cells of the Algae in their embrace, and so on. We may
make an attempt to explain the fact that certain parasitic germ-tubes perforate the
epidermis of one species of Phanerogams and not of others by assuming the secretion
of specific ferments and specific differences in the structure, firmness or cuticularisa-
tion of the membranes of the host; but it is scarcely possible to explain from the
data before us why a germ-tube bends its extremity towards the membrane of the
proper host and not towards every membrane or moist surface, or even turns only
towards the outer edges of the lateral walls of the epidermal cells, as in the cases
mentioned above. Are specific physical irritations brought into play in these cases,
or chemical stimulations, which may be supposed to operate through unknown
secretions from the surface of the host, with certain specific reactions on the part of
the parasite? Questions of this kind present themselves here at every turn, as they
do in some similar phenomena which occur in the saprophytes, and offer very
promising subjects for experimental enquiry’.

Section CIII. The parasite pursues its further development as soon as
it has attached itself to the host, while the living host reacts on the plant which
occupies it permanently and sometimes continues to spread through it; this reaction
varies extremely in different cases, being everywhere determined by the specific qualities
of the symbionts. The chief phenomena attending these processes will be briefly

1 Pfeffer's work on chemical stimuli, which appeared some time after the above words were
written, has shown more distinctly the way to the answering of these questions, and has made some
advance upon it. See Ber. d. Déutschen Botan. Ges. 1883, and Unters. d. Bot. Instit. zu Tiibingen, I,
Heft 3 (1884).

CHAPTER VII.—PHENOMENA OF VEGETATION.—PARASITES. 367

described in the following paragraphs and will be illustrated by examples. Some of
them have been already noticed in passing in the sections of Chapter V, where they
will be readily found with the help of the index. Further details must be sought in
the different monographs and in pathological treatises.

Among the phenomena which are of quite general occurrence it may be
mentioned in connection with the growth of the parasite, that in extreme cases it
either continues to be confined to the spot where it first attacked its host and to its
immediate neighbourhood, or spreads far beyond that spot; in the latter case
it may grow through or over the existing parts of the host for considerable dis-
tances, or part passu with the growth of the host, as is specially seen in many
Lichen-fungi. In smaller hosts consisting of one or few cells, with the exception of
the Lichen-fungi which will be described at length in the sequel, the difference
between these cases is of course small; in larger plants on the contrary it is very
striking. The Laboulbenieae, for instance, which are parasites on insects are narrowly
confined to the part which they first attack ; the species of Cordyceps which belong to
the Entomophthoreae grow through the entire body of the insect. Many corresponding
examples might be mentioned from parasites on plants, and it need scarcely be added
that there is no want of intermediate forms between the two extremes.

Parasites which spread through the whole of the host, or over large portions of it,
may either show the same behaviour and the same development on every or almost
every part of the body, or they may have certain phases of their development confined
to certain parts, and this latter rule may be invariable or be very generally observed.
Parasites on insects, species of Cordyceps for example, spread almost through the
entire body of the creature; C. militaris puts forth its stromata at any part
without distinction of the surface of the caterpillar which it attacks, often at many
places at the same time; C. sphecocephala only on the under surface of the thorax
between the first or between the two first pairs of feet of the West Indian wasp
(Polistes Americanus) which is its host’. The same rule will be exemplified below
in the case of very many parasites on plants, and has been already noticed to some
extent in Chapter V.

According to their effect on the host and the reactions of the host on this
effect, two chief classes of parasitic Fungi may be distinguished, namely, a destructive
and a Zransforming or deforming class; the two extremes are united by a large
number of intermediate forms.

When a parasite of the destructive class attacks and occupies its host the parts
attacked by it become sickly, die, and are decomposed in a longer or shorter time
without previously showing any signs of abnormal growth. It depends on the
particular species whether these phenomena in large plants are confined to the parts
directly attacked by the parasite or whether the whole body of the host becomes sickly
and dies. All facultative parasites may be placed in this class, as will be shown in detail
below; of obligate parasites on plant-forms the species of Phytophthora almost
without exception, many Uredineae, such for example as the species of Puccinia which
live on the Gramineae, or at least those portions of their life-cycle which inhabit
the grass, and with some exceptions the Ustilagineae (species of Tilletia, Ustilago

1 See Tulasne, Carpol. III.

368 DIVISION IIL—MODE OF LIFE OF THE FUNGI.

Carbo, Claviceps, and many others) belong 'to the same category, together with all
those thatlive on animals, unless we choose to reckon the phenomena ofinflammation,
suppuration, and formation of tumours caused by.the presence of the Fungus
in warm-blooded animals as cases of abnormal growth, a point which may for
the present remain undecided.

The occupation bythe deforming parasite is followed immediately byanomalous
processes of growth in the host or in the parts of the host, the word anomalous being
here understood to mean every condition different from that which is found in the
plants or the parts not attacked by the Fungus. Countless examples of this class of
parasites are to be found among those which live on plants. The phenomenon
necessarily presupposes a power of growth in the parts to be deformed, and in the
‚higher plants therefore it usually implies that they were attacked in the young state
when their growth is still incomplete.

The extremes of deformation, which pass, it is true, readily into one another, consist
on the one hand inan abnormal increase of growth and abnormal enlargement of parts of
the tissue, which are in other respects normal and normally disposed, and hence in the
swelling of the individual cells, as in the case of epidermal cells which are occupied by
Synchytrium and the adjoining cells, or else in a monstrous enlargement and inflation of
entire members and aggregates of members in the higher plants, such as the swelling of
the flower-stalks and the enlargement, often to an enormous size, of the flowers of the
Cruciferae when attacked by Cystopus. These may be said to be cases of Aypertrophy.
On the other hand the parts may be deformed with very slight or with no hypertrophy
worth mentioning; such are well-known deformations of the shoots of herbaceous
species of Euphorbia by Uromyces Pisi, U. scutellatus, and Endophyllium Euphorbiae,
and the ‘witches’ brooms’ on the branches of the fir and cherry-tree when attacked by
Peridermium elatinum or Exoascus. In the fir (Abies pectinata), for example, these
branches grow vertically upwards, like small trees, from the horizontal limbs, with
branches spreading in every direction, and leaves which spread in the same manner and
fall off year by year, while the entire excrescence continues to grow for years‘. In the
flowers of Knautia arvensis, when occupied by Peronospora violacea, the stamens often,
though not always, acquire the characters of normal petals of a beautiful violet colour,
and the blooms are filled by them. These phenomena of deformation by Fungi may
be termed mycelogenelic metamorphosis. The processes in the formation of Lichens, to
which we shall recur in a later page, have a considerable resemblance to them.

Lastly, the new formation of members, such as are not seen in any form on the
plant when free from the Fungus, are caused on parts of some of the higher plants by
the presence of the Fungus. The most striking instances of the kind are the delicate
round bodies of the size of a cherry which Exobasidium Vaccinii produces on the
leaves of the alpine rose, and the excrescences on the stem of Laurus canariensis, L.
caused by Exobasidium Lauri and described at length by Geyler *,—club-shaped for-
mations with blunt edges, of the length of a finger, and branched like an antler,
which Schacht even mistook for aerial roots. But the strangest example of the kind
is found in the Saprolegnieae when attacked by Rozella, which will be described below.

' Bot. Ztg. 1867, p. 237.
? Bot.-Ztg. 1874, p. 321.

CHAPTER VII.—PHENOMENA OF VEGETATION.—PARASITES. 36 9

Excrescences of the kind just described and local hypertrophies caused by Fungi
have been fitly compared with galls and have sometimes received that name.

It is obvious that all these mycetogenous deformationsand new formations and the
phenomena also of simple destruction are in direct causal connection with the process
of feeding the Fungus. In the latter case we see directly that the Fungus grows at
the expense of the parts which are destroyed, the substance of its own body constantly
increasing. In the case of tumours and hypertrophies there is often at first a striking
over-production of building material, as starch, and this is afterwards used for the com-
pletion of the development of the Fungus. In connection with this it often happens
that the parts deformed by the Fungus are also killed prematurely; they die and are
decomposed sooner than the same parts when free from the Fungus and not deformed.
But every conceivable gradation is found in this respect in different species and some-
times in different individuals between the parasitism which quickly destroys its victim
and that in which parasite and host mutually and permanently further and support
one another,—the relation which is most conspicuous in the formation of Lichens
and which Van Beneden ! has termed mufualism.

The phenomena here touched upon have not been submitted in any case to a strict
physiological analysis; but the general nature of the enquiry is so obvious that it is
unnecessary to discuss it here.

In the following summary of the chief phenomena and combinations which
actually occur we must keep the Fungi which live on animals distinct from those
which inhabit plants.

FuncI WHICH ARE Parasitic on ANIMALS.

Section CIV. The Fungi which attack the bodies of living animals furnish
a series of instructive examples of the phenomenon of facultative parasitism (see
page 356).

A number of species of Eurotium and Aspergillus (Sterigmatocystis), which all
occur chiefly as saprophytes and in that mode of life reach their full development, in
some cases even forming sporocarps, are able to migrate to the bodies of warm-
blooded animals and live at their expense, producing an abundance of typical gonidia,
but not, as far as we know, arriving at the formation of sporocarps. Their vegetation
causes or promotes a diseased state of the parts, known to physicians as mycoszs.
Aspergillus flavus, A. niger and A. fumigatus, Eurotium repens and Aspergillus
glaucus are characteristic promoters of the disease of the human ear which bears the
name of ofomycosis aspergillina”. The Fungi find a nidus in the diseased (serous) or
excessive normal secretions of the skin, and their rapid growth causes inflammation
and excoriation of the parts. But in these cases, as Siebenmann urges, they do not
penetrate through the epidermis and are not developed in the healthy ear, so that they
virtually retain their saprophytic character, however decidedly they must be considered
to be promoters of disease.

-1 Animal Parasites and Messmates (Internat. Scientific Ser. xix). See also De Bary, Die
Erscheinung d. Symbiose, Strasburg, 1879.
2 Siebenmann, Die Fadenpilze Aspergillus, &c. u. ihre Beziehungen z. d. Otomycosis aspergillina,
Wiesbaden, 1883 ; many special treatises on the subject are enumerated in this publication,

[4] Bb

370 DIVISION III.—MODE OF LIFE OF THE FUNGI.

Aspergilli of this kind, one of which has been certainly determined as Asper-
gillus fumigatus, have been found since 1815, and especially since Virchow’s more
recent and more exact account of them, spontaneously developed in the human
lungs and in the air-passages of birds. They find their way there no doubt, as they
reach the ear, with the dust which mingles with the atmospheric air, and meet with
similar conditions and adopt a similar mode of development. Gaffky and others,
Lichtheim especially, obtained characteristic phenomena of development, in this case
phenomena of disease, when the gonidia of Aspergillus fumigatus and A. flavescens,
Eidam, two species distinguished by the high optimum of their vegetative temperature,
over 37°C., were introduced by injection into the blood of animals, such as rabbits and
dogs. On the other hand, Eurotium Aspergillus glaucus, E. repens, Aspergillus niger,
and Penicillium glaucum, the latter of which was once unjustly suspected by Grawitz,
were proved by similar experiments to be incapable of development in animal bodies,
and therefore harmless.

Lichtheim found that the facultative parasitism of the two species of Mucor
noticed above on page 359 was perfectly analogous with that of the two species of
Aspergillus just mentioned, with the limitation only which was also noticed before,
that Mucor rhizopodiformis has no endophytic development in the dog.

The spores of these Fungi introduced by injection into the blood-passages are
carried through them into all parts of the body. It would appear that they do not
germinate in the blood-current itself, but in certain organs of the animal into which
they are conveyed by the blood. The living organs show different degrees of liability
to the attack of the Fungus, especially when the spores are injected in smaller
quantities, and Lichtheim arranges them in the following descending series for the
Mucoreae: kidneys, Peyer’s patches, mesenteric glands, spleen, marrow, liver.
Similar results appeared with Aspergillus fumigatus, but with less regularity and with
a characteristic localisation of the Fungus in the membranous labyrinth. The living
brain remained free in all cases from the development of the Fungus. But when the
organs are dead the germination and development of the Fungi takes place in all in
the same degree. The spores develope mycelia in living bodies, but it is only in
exceptional cases that a fresh formation of spores takes place. The development of
the Fungi is attended by characteristic local derangements, and these produce dis-
turbance of the general health, for a fuller account of which the reader is referred to
medical works* and especially to Lichtheim.

Spontaneous Aspergillus-mycosis and Mucor-mycosis in internal organs re-
moved from direct access of air is to say the least a doubtful occurrence.

Many Fungi living in insects are obligate parasites. Everything of im-
portance that is known of the development of the epiphytic Laboulbenieae which
belong to this category has been stated at page 263. Their dissemination by
means of the spores conveyed from one insect which has been attacked by the
Fungus to another, especially during the act of conjugation, has been clearly described

1 See especially Virchow, Archiv, IX (1856), p. 557,-—Fresenius, Beitr. p. 84,—Lichtheim,
in Berliner klinische Wochenschrift, 1882, Nr. 9 and in Zeitschr. f. klin. Med. VII, Hft. 2.—Gaffky,
Mittheil. aus d. k. Reichsgesundheitsamt, I, 526. These papers contain further notices of the
literature of the subject.

CHAPTER VII.— PHENOMENA OF VEGETATION.—PARASITES. 371

by Peyritsch! in the case of the house-fly. The health of the insect attacked by
these epiphytes seems to be very little disturbed.

The development of the Entomophthoreae which attack insects has also been
given above (page 158). We may add here that the body of the insect is occupied in
essentially the same way as by the species of Cordyceps which will be described
below. The Entomophthoreae, like the Laboulbenieae, are, as far as is known, strictly
obligate parasites, and go through the whole course of their development, with the
exception only of a brief stage of germination, in and on their host while it is either
still alive or recently killed by their vegetation.

The life-history of the species of Cordyceps which attack insects is more
complicated. Cordyceps militaris, as examined in caterpillars, may be taken.

C
N
A
C B
N A)

FIG. 165. Cordyceps militaris, Fr. A secondary spores from the asci germinating in water on a microscopic slide.
« a single spore with one of its germ-tubes erect and b d, its ity and the b hes having formed chains of
gonidia. & three secondary spores germinating; the germ-tube of one of them has risen into the air and formed a chain of
gonidia on its apex. B extremities of hyphae which have p igh the chi skin of a caterpillar, have reached
its inner surface and are abj drical gonidia. c cylindrical gonidia with sprouts, from the blood of a caterpillar
attacked by the Fungus; one extremity of @ is fixed in a blood-cell. £ extremity of a filiform gonidiophore which has grown
out of the skin ofa caterpillar of Sphinx Euphorbiae killed by the Fungus and converted into a sclerotium. Magn. about
400 times.

as an example” The ascospores formed in the orange-coloured club-shaped
stromata are ejected as narrowly filiform or rod-shaped bodies divided by transverse
walls before they leave the ascus into a row of many shortly cylindrical secondary.
spores, which are at least 160 in number. When placed in any fluid, they usually
separate from one another, swell slightly, become rounded in shape and then put out
germ-tubes (Fig. 165, 4); sometimes, but not always, the spores become partially
united together again by means of short connecting tubes before they germinate.
Germination takes place on the surface of the skin of a caterpillar if it is only slightly
moist. The germ-tubes penetrate at once, and at any part of the surface, into the
chitinous skin of the insect. Here they enlarge into somewhat stouter fungal hyphae,
which ramify and in the simplest case make their way by a sinuous course into the.
deeper layers of the skin, at length reaching the inner surface and insinuating them-
selves between the bundles of muscles and lobes of fatty substance of the creature.

1 As cited on page 273.
® Bot. Ztg. 1867, p. 1, and 1869, p. 590.
Bb 2

372% DIVISION IIl-—MODE OF LIFE OF THE FUNGI.

Here their further growth in length ceases; but now begins, sometimes even within
the soft inner layers of the skin itself, the successive abjunction apparently in small
quantities of longish cylindrical gonidia, known from their shape as cylinder-gonidia,
partly on the extremities of the primary branches, partly on short lateral branchlets
(Fig 165 2). From the place of their formation these pass at'once into the blood
which fills the cavity of the body, where they elongate to twice or several times their
original size, and divide repeatedly by transverse walls, and then begin to develope like
Sprouting fungi, i.e. they produce repeated orders of similiar cells by terminal and
lateral sprouting (Fig. 165 C). These cells are disseminated through the blood
by the movements of the insect and fill it by degrees in a dense mass. They
also penetrate into the blood-cells or are embraced by them in the conrse of the
amoeboid movement of the latter (Fig. 165 C, d). They grow at the expense
of the blood, which diminishes in quantity to such a degree that the insect at length
loses its normal turgidity, becomes soft and relaxed and in this state dies. As soon as
death has taken place all the sprout-cells begin to develope rapidly at the expense of
the substance of the dead body into copiously branching hyphae, which not only fill
the entire cavity of the body which till now contained the blood with a dense weft
and expand it to its former size in the turgescent state, but grow in a dense mass
through all parts of the body, except the intestinal canal which remains empty, and
to a great extent absorbs them. A body is thus formed in 1-2 days’ time which
retains the shape of the living insect, but consists of a close weft of fungal hyphae with
some small remains of the body of the insect. This Fungus-body with the form of
an animal has the biological peculiarities of a sclerotium. It can give rise directly to
fresh stromata, and can do this in a few weeks after its formation if it lies in a moist
state; if it is dried, it passes into a resting-state the maximum duration of which is
not exactly determined, but it may certainly continue for some months without pre-
judice to the power of further development. Such is the course of development of
Cordyceps in its simplest form.

But deviations from this course and complications of it occur not unfrequently,
of which the following are the most important. If its ascospores are sown in water
or in nutrient solutions without a living host, they germinate and the germ-tubes
develope hyphae which branch with more or less copiousness according to the amount
of nourishment supplied ; in water only small plants are produced with few or no
branches (Fig. 165 A, a, 5). Some of the branches spread as a mycelium in the
nutrient solution, and have the power, like the hyphae on the inner surface of the cater-
pillar’s skin, of abjointing cylinder-gonidia. It is true that this has not been observed in
the species in question, but it may be safely assumed since it has been observed in
Botrytis Bassiana, which agrees with Cordyceps in all these biological relationships.
Other branches of the germ-plants rise erect from the fluid into the air and branch,
forming whorls of ramifications on the extremities of which they serially and successively
abjoint gonidia (see p. 66), The first gonidia on the young germ-plants are cylindrical
like those in the body of the insect (Fig. 165 A, 4), only usually shorter. All the
succeeding ones, even the second in arow which began with a cylindrical gonidium,
are spherical in form; they may therefore be called round or aerial gonidia. The
mycelium also which is developed in the dead body of the caterpillar very often
produces gonidia of this kind only and no cylindrical ones.

CHAPTER VII.—PHENOMENA OF VEGETATION,—-PARASITES. 373

The gonidiophores of these plants on most of the caterpillar-bodies examined,
which also bore stromata, were observed to be small hyphal branches with whorls
of branchlets like the germ-plants just described (Fig. 165 £), and these together
formed a delicate down on the surface. But on other insects they grow into a
dense mould-like covering some millimetres in height and white with a dust of
countless gonidia, or else like the Coremium-form of Penicillium they form club-
shaped Fungus-bodies ı-2 centimetres in height and covered all over or in the upper
part, which is borne on an orange-yellow stalk, with a felt of branchlets which abjoint
gonidia. The last-named bodies are known as form-species under the name of
Isaria farinosa. Both the Isaria-form and mould-covering are found commonly on
a sclerotioid insect-body by themselves, i.e. without the stromata. I once succeeded
in obtaining two poorly developed stromata with some large Isarieae from a
caterpillar of Spinx Euphorbiae infected by ascospores, which had changed to the
chrysalis state after infection.

Gonidiophores with the round aerial gonidia are also obtained if cylinder-gonidia
from the still living insect or portions of the mycelium from the insect converted into
a sclerotium are cultivated in the air on a suitable substratum; the amount of
luxuriance with which they are developed varies with the supply of food. They are
formed too under the same circumstances on small plants, which proceed from germ-
tubes produced at once in a fluid from the aerial gonidia themselves. These germ-
tubes do not ultimately penetrate into the skin of the insect, at least not in the
experiments made with the caterpillar of Sphinx Euphorbiae. When the insects are
sprinkled with the spores the germ-tubes are seen to enter the tracheae through the
stigmata, and then to bore through the wall of the tracheae and so reach the cavity
of the body, where the cylinder-gonidia are then abjointed and disseminated, and
sprout; at length the insect dies and becomes a sclerotium, exactly in the way
described above in the case of the direct products of the ascospores. Stromata
have never been known to be formed on insects killed by infection with aerial
gonidia, only a fresh crop of aerial gonidia especially of the Isaria-form.

The Fungus therefore which we are describing can only arrive at its full develop-
ment, that is, can only form perithecia, as an obligate parasite, and to this mode of
life it is closely adapted. When it ceases to be a parasite and the dead insect
becomes a sclerotium, we see a saprophytic stage of the existence of the plant follow
upon the strictly parasitic stage. When the conditions for a parasitic mode of life are
withdrawn, facultative saprophytism takes its place (see page 356), and a new form
of adaptation may make its appearance with the formation of aerial gonidia accom-
panied also with the normal formation of perithecia. The entrance upon the
parasitic mode of life is however comparatively easy, because the formation of all kinds
of spores takes place abundantly in nature, especially in wooded places frequented by
the insect-hosts. All that is known of the mode of life of other insect-killing Fungi
allied to Cordyceps militaris agrees entirely with the account here given of that
species.

The foregoing account of the life-history of Cordyceps is founded chiefly on the
facts observed on infecting the caterpillars of Sphinx Euphorbiae with the Fungus,
and on investigations some of which have not hitherto been published. I make this
latter remark, because the statements agree so exactly with the account given by

374 DIVISION III— MODE OF LIFE OF THE FUNGI.

myself! and supplementing that of Vittadini? of Botrytis Bassii, the Fungus of the
“muscardine’ of the silk-worm caterpillar which was formerly only known to produce
gonidia, that it might be thought that I had simply transferred the observations on
the one species to the other. The truth is that the two agree perfectly with one
another.

Slight deviations from the course described in one species of insect occur in the
case of other species both in the reaction of the insect on the effects produced by
the parasite as well as in the development of the latter, as I have shown in another
place in connection with Botrytis Bassiana. A case of such deviation may be mentioned
here as occurring in Cordyceps. The caterpillars of Sphinx Euphorbiae when infected
with the ascospores were killed in from fifteen to twenty days, and the spots in the skin
infected by the Fungus showed, as in Botrytis Bassii, nothing beyond a brown discolo-
ration varying with the individual and spreading all round from the intruded hyphae.
The process was somewhat different when the caterpillars of Gastropacha Rubi
were infected. First of all it was much slower; of seventeen specimens infected the
first died in about thirty days, the last not till after the lapse of seventy days, and
death was preceded by slowly increasing weakness. In the second place the skin
showed signs of disease in the spots where the spores had been sown after the Fungus
had penetrated into the live insect, but long before its death; it swelled up and became
of a darker colour and hard, and was covered with a delicate white mould composed
partly of the regular verticillately branched gonidiophores of the species, partly of
accumulations of small roundish colourless cells and shortly cylindrical pieces of
hyphae divided by a few transverse walls. These hyphae not unfrequently abjointed
normal gonidia on narrowly conical lateral branchlets. It could not be determined
whether these structures were produced by the breaking up of mycelial hyphae or
by the development of normal gonidia. They showed themselves to belong to Cordyceps
by the fact that they all gave rise to mycelia with characteristic verticillately branched
gonidiophores when cultivated on microscopic slides. ;

The above statements respecting the entrance of the Isaria farinosa-form into the
host are reproduced from my paper in the Botanische Zeitung for 1869, which should
be consulted for further details. In this paper and in that of 1867 I gave expression to
some doubts with respect to the view maintained by Tulasne®, that Isaria farinosa
belonged to the cycle of development of Cordyceps militaris ; these doubts were sug-
gested partly by the failure of attempts to obtain stromata and Isaria-forms in turn
from one another in specimens under cultivation, partly by differences, which it is true
were only quantitative, in the ramification of the branches producing gonidia. The
latter objection might easily be dismissed, and as has already been remarked in the text
I do not now think it necessary to maintain the first. A caterpillar of Sphinx Euphorbiae,
which had become a sclerotium as usual after infection by ascospores, when laid on moist
sand produced first of all two small stromata provided with normal perithecia.
These died before the asci were fully formed, and then Isaria was produced in
abundance. Portions of mycelium cultivated on microscopic slides bad already
afforded Isaria. In this case therefore either Isaria was uitimately produced from
the ascospores, or the insect had been infected with them and unintentionally also
with Isaria, which in the end stifled and supplanted the form with perithecia. I have
no reason for assuming such accidental mingling of the two forms, and have framed my
opinion accordingly ; at the same time the possibility of the mixture is not excluded
and it was necessary to call attention to that fact.

For some further remarks on Cordyceps, Botrytis Bassii and some other forms see
above, page 253.

1 Bot. Ztg. 1867.

® Della natura del Calcino o mal del segno (Giorn. Instit. Lombard. III (1852), p. 142, u. t. 2)
® Carpol.-III,

CHAPTER VII.—PHENOMENA OF VEGETATION.—PARASITES. 375

Section CV. Our knowledge of the Fungi which are parasitic on animals,
other than those contained in the groups which have now been considered, is so
small from the botanical point of view, that, with. all due acknowledgment of the
medical interest of these plants and medical research, we can only touch upon them
briefly in this place. In doing this we shall refer especially to the medical works on
the subject andto important special treatises, from which the reader will obtain further
directions if he wishes to examine the somewhat profuse literature in greater detail’.
We cannot of course enter here into purely medical questions.

The most important of the plants in question are the parasitic Saproleg-
nieae, the Fungi which cause diseases of the skin in warm-blooded animals,
men included, the Fungus of thrush or aphthae, and Actinomyces. Some
kinds comprised in this class are quite doubtful.

Parasitic Saprolegnieae. Numerous cases are recorded in which living fish,
such as gold-fish, and other creatures living in water, as salamanders and frogs, were
attacked by Saprolegnieae, grew sick and died* Destructive epidemics among
salmon have recently been reported, especially in the English and Scottish rivers, and
these epidemics are characterised by the development of Saprolegnieae®. We learn
from Huxley’s investigations that the Fungus settles on portions of the skin of an
apparently healthy fish where there are no scales and sends mycelial or rhizoid-
branches through the epidermis into the inner layers of the skin, causing at first local
and then general disturbance of the system. Similar statements are made in other
cases. The examination of the Fungus has only shown that it is some form of
Saprolegnia. The formation of oospores, on which the determination of the species
depends, was either not observed or imperfectly described. Disregarding Huxley’s
results for the moment, we may gather from the statements before us that the Fungi
in question are ordinary Saprolegnieae, which must have migrated to the living animal
as facultative parasites, since they usually vegetate as saprophytes (see page 141). If
this is so, there must have been some peculiarity in the fishes before they were attacked
by the Fungus, which is not found in the same fishes in the natural state; there must
be some special reason for their being attacked by the Saprolegnia, perhaps
a disease of some other kind which we must not enquire further into here; for the
ordinary species of Saprolegnia are so abundant in our streams and lakes, that if they
could attack the fish indiscriminately as facultative parasites, not one could possibly
be free from the Fungus. Direct experiments also have shown me that healthy gold-
fish may continue lively and free from the Fungus for months in water, in which
Saprolegnieae kept purposely in large quantities were forming an abundance

1 The material collected from time to time will be found in the following publications :—
Ch. Robin, Hist. nat. d. végétaux parasites qui croissent sur homme et les animaux vivants,
Paris, 1858.

Kuchenmeister, Die af u. in d. Körper d. Menschen vork. Parasiten, II, Leipzig, 1855.

Steudener in Volkmann’s Samml. klinischer Vorträge, Nr. 38, Leipzig 1872.

Baumgarten, Pathogene Mikroorganismen, I. (Deutsche Medic. Zeitung, 1884, 1).

? Hoffmann in Bot. Ztg. 1868, p. 345, and the older works on the Saprolegnieae noticed above
on page 145.

5 Huxley in Nature, Vol. XXV (1881-1882), p. 437. See also the English reports in Just’s
Jahresber. V, 96, 456, IX, 253.

376 DIVISION III.—MODE OF LIFE OF THE FUNGI.

of spores. It would of course alter the case if there were distinct parasitic species
of Saprolegnia different from the common ones, but we know of no such species
at present.

The remarks here made apply on the whole to the epidemic among salmon
investigated by Huxley, but some points require further explanation. The Fungi in
this case appear on the outer surface of the skin in the form of ordinary Saprolegnieae ;
they could be transferred by tapping to dead flies and be made to develope further on
them, but their gonidia are described as being always without motion. This at once
raises the question whether they really belong to Saprolegnia, and at any rate it is
quite uncertain whether we are dealing with a case of facultative parasitism in
species which are usually saprophytic or with one or several peculiar and specifically
parasitic forms.

Section CVI. The following are the best-known species of Fungi of
diseases of the skin. Achorion Schoenleinii, Remak, the Fungus of favus,
Trichophyton tonsurans, Malmsten, the Fungus of ringworm or tinea (herpes)
tonsurans which is identical according to Köbner with that of sycosis or mentagra
parasitica (Microsporon Audouini and M. Mentagrophytes, Rob.; Microsporon
furfur, Rob., the Fungus of pityriasis versicolor'). These Fungi are parasitic on the skin
of different mammals and birds. They grow luxuriantly in and beneath the epidermis,
in the hair-follicles and hairs. Their appearance on the human skin is characterised’
by the forms of disease enumerated above. Trichophyton tonsurans has also been
observed on horned cattle, horses, dogs, and rabbits, Achorion on the domestic mouse,
the rabbit and the head of domestic fowls; Microsporon furfur was seen by Köbner
on rabbits after inoculation. They may all be conveyed from one individual to another,
from men to other animals and vzce versa by sowing their spores, and as these develope,
the characteristic disease in each case makes its appearance. Transference by
inoculation can be successfully performed on sound individuals, but certain forms of
predisposition in the patient, which we cannot discuss here, appear to favour or to
hinder the development of the Fungus.

Of these Fungi as they appear in and on the portions of the skin attacked by
them we know only the septate mycelial hyphae, the branches of which divide trans-
versely into rows or chains of spores capable of germination and resembling those
of Oidium lactis or the chain-gemmae of Mucor (see pages 67 and 155). When

1 Remak, Diagnost. u. Pathogen. Unters. Berlin (1845), p. 193.

Köbner, Ueber Sycosis, &c. in Virchow’s Arch., XXII (1861), p. 372;—Id., Klinische u. experi-
mentelle Mittheil. aus d. Dermatologie u. Syphilidologie, Erlangen, 1864.

Strube, Exanthemata phyto-parasitica eodemne fungo efficiantur (Diss. inaugur. Berolini, 1863).

J. Lowe, On the identity of Achorion Schönleinii and other veg. parasites with Aspergillus
glaucus (Ann. mag. nat. history, ser. z, XX (1857), p. 152).

W. Tilbury Fox, Skin diseases of parasitic origin, London, 1863.

Kleinhans, Die parasitären Hautaffectionen, Erlangen, 1864.

P. J. Pick, Unters. ii. d. pflanzlichen Hautparasiten (Verhandl. d. Zoolog-Bot. Ges. in Wien,
XV, 1865).

J. Peyritsch, Beitr. z. Kenntn. d. Favus (Medicin. Jahrb. Bd. XVII, Wien (1869), Heft II, p. 61).

P. Grawitz in Virchow’s Archiv, 70, p. 546. =

Ed. Lang, Vers. einer Beurth. d. Schuppenflechte (Vierteljahrschrift f. Dermatologie u. Syphilis,
1878, p. 333) ;—Id., Vorläuf Mittheil. ii. psoriasis (Ber. d. naturw. Med. Vereins z. Innsbruck,
VIII, 1878).

CHAPTER VII.—PHENOMENA OF VEGETATION.—PARASITES, 377

fresh spores also are sown in nutrient solutions the germ tubes which are at once
emitted develope only mycelia producing spores in the manner just described. In
this respect, according to Grawitz, Achorion, Trichophyton, and Microsporon are
exactly alike, but they differ from one another in size. This difference is attributed
by Grawitz to differences in the food, which can no doubt give rise to great diversity
of size in the same species, and he therefore considers the three forms as belonging
to one and the same species; and he further identifies this species with Oidium lactis,
partly on the ground of the resemblance of the three forms when grown in a nutrient
solution to Oidium, and partly because inoculation with pure Oidium will produce
diseases of the skin which resemble a mild herpes.

The view that these four forms belong to one another cannot on our part be
summarily rejected, but at the same time it requires further proof. In any case the
comparison with the Mucor which forms gemmae shows that those forms do resemble
imperfectly developed states of other known species of Fungi with typical gonidia and
carpospores. Hence the question arises whether organs of this description are to be
found also in skin-parasites. On the answer that may be given to this question will
depend the determination of the special qualities of these Fungi as parasites. At
present the question is still unanswered, though many attempts have been made to
solve it in past times by means of artificial cultivation ; but Saccharomyces, Penicillium,
Eurotium and all sorts of Moulds made their appearance in the impure material used
for these experiments, and then the skin-parasite was introduced in one. way and
another without reasonable ground into the cycle of forms of these species, as
Peyritsch long since clearly showed.

It has been proved by experiment that Saccharomyces albicans, Reess
(Oidium albicans, Robin) causes a formation of pustules and scab, known as thrush or
aphthae, on the mucous membrane of the mouth, throat, and oesophagus especially in
young individuals. Grawitz and Reess' have recently shown that the plant is a
form of Sprouting Fungus with long cells resembling Saccharomyces Mycoderma ;
its ascospores have never been observed ; it does well as a saprophyte, but excites
weak alcoholic fermentation in saccharine solutions and is therefore a facultative
parasite. It has yet to be determined whether it is identical with S. Mycoderma
(the flowers of wine) or with some similar form.

Section CVII. The name of Actinomyces Bovis has been given by Harz to
a remarkable growth discovered by Bollinger and Israel which occurs in peculiar
swellings on the jaw-bone, especially in cattle, and is in causal connection with them,
but is also found inside certain parts of the body in pigs and men ?. In the swelling,

1 Grawitz in Virchow’s Arch. 70, p. 566, and 73, p. 147.—Reess, Ueber d. Soorpilz (Sitzgsber. d.
Phys. Med. Ges. zu Erlangen, 9 Juli 1877 and 14 Jan. 1878). The literature of the subject
is given by Kehrer, Der Soorpilz, Heidelbg. 1883.

2 Bollinger, Ueber eine neue Pilzkrankheit beim Rinde (Centralbl. f. med. Wiss. 1877, Nr. 27).

J. Israel, Neue Beob. v. Mycosen d. Menschen in Virchow’s Arch. 74 (1878), and 78.

O. Harz, Actinomyces Bovis. (Deutsche Zeitschr. f. Thiermedicin, 1. Supplementheft (1878),
p- 125). See also in the same publication, p. 45.

E. Ponfick, Die Actinomycose d. Menschen, Berlin 1882.

Johne, Die Actinomycose (Deutsche Zeitschr. f. Thiermedicin, VII, (1882), p. 141, tt. 8-10).

Pusch, Ueber Lungenactinomycose (Arch. f. wiss. u. pract. Thierheilkunde, IX (1883), p. 447).
In this paper the different works on the subject are most fully enumerated.

378 DIVISION III.—MODE OF LIFE OF THE FUNGI.

which we must not describe at greater length in this place, Actinomyces forms yellow
bodies like sand-grains about 1 mm. in diameter. The larger of these bodies, which
are visible to the naked eye, always consist of a number of single growths of
Actinomyces united into a mass by the soft swollen tissue.

Each Actinomyces may be best described as a round or less commonly
elongated hollow body sometimes pressed flat with a relatively thick wall and narrow
cavity. The wall looks like a dense hymenomycetous or discomycetous hymenium
with very slender elements, being composed of filaments which are copiously branched
and have their branches at right angles to the surface and therefore radially disposed
when the form of the body is round, and are crowded close together and difficult to
separate from one another. Many of these crowded branches are club-shaped at their
outer extremity, and in this point again therefore may be compared with asci or narrow
hymenomycetous basidia ; some are constricted and torulose. They mostly end at a
uniform height in the smooth outer surface of the body, though single ones some-
times extend a long way beyond the rest according to the figures which are given (see
Ponfick, t. vi).

The inner cavity ofthe body, which is surrounded by this kind of wall and as
was said is comparatively narrow, is filled with a dense tangled mass of slender much-
branched filaments, the branches of which are continuous with those of the wall.
Roundish or elongated grains of about the thickness of the filaments and not
unlike small spores are found between the filaments, at least in some specimens.

The filaments appear to be filled with a homogeneous protoplasm, in which
single granules or perhaps vacuoles are rarely to be distinguished ; it is uncertain and
a disputed point whether they are septate. They attain at most a breadth of 2-3» in
the broadest parts of the club-like swellings which I could find, in other parts
scarcely a third of that measurement,

The Actinomyces is sometimes incrusted with lime.

The structure of Actinomyces certainly favours the view that it is of the nature of
a Fungus, but it has no closer resemblance than this to well-known Fungi. It is not
possible therefore to assign it a place in the system, or to form any clear idea of the
history of its growth and development from the analogy of other Fungi. Experiments
in its cultivation outside the body of the animal have yielded no results of importance
to our knowledge of its development. All that can be said about it is founded entirely
on the state of things observed in the creature attacked with actinomycosis either
living or dead. From the experiments of Ponfick and especially of Johne it would
seem possible that Actinomyces grows, because when fresh matter was introduced by
inoculation beneath the skin or in hollow places in the bodies of horned cattle, the
specific swellings containing Actinomyces were produced in them even in parts of the
body at a distance from the places where the inoculation was performed. That the
latter were a new growth and not the individuals introduced by the inoculation is
certainly not proved, but is not to be disputed; at any rate there can be no doubt that
actinomycosis is produced by inoculating with Actinomyces, We can frame concep-
‚tions of our own as to how growth is eventually brought about, but none of them rest
on a secure foundation.

The same writers found often in fresh material the club-shaped elements of the
wall-layer separated from one another, and a large number of club-shaped sprouts

CHAPTER VIl.—PHENOMENA OF VEGETATION.—PARASITES. 379

shooting from them, especially from their basal portion, so that the whole was palmately
lobed in form; these clubs, or also, as is stated, portions of them delimited by
transverse divisions, may then be regarded as spores (‘gonidia, conidia’), the
sprouting or branching of which may give rise to a new plant. On the other hand
‚we must not forget the round bodies which are sometimes found in the inner cavity
and which may be spores, nor the occurrence of small plants which consist almost
entirely of the slender filaments and the origin of which from the sprouting of the
clubs is not fully explained. But all this still leaves us in entire ignorance of the real
history of growth.

The failure of the attempts which have been made to cultivate Actinomyces
outside the body of an animal, supposing always that it is really a plant, leads
naturally to the assumption that it is an obligate parasite. But even this may be
doubtful. From the experience of the pathologists who relied chiefly on the local
occurrence of the swellings, it is probable that the surface of the mouth and throat
and in some cases small wounds on them are the parts where the presumed parasite
makes its entry and attacks the animal, and that it is conveyed there with the food.
Johne frequently found in the pockets of the tonsils of pigs, even when the animals
were quite free from actinomycosis, small bits of plants rough with spikes, such as
bits of the awns of grain and the like, and Fungus-bodies resembling growths of Actino-
myces attached to them in considerable quantities. Further investigation is required
to explain the true meaning of all these observations.

A peculiar disease known as the madura disease, which is endemic in some districts
of India and causes dangerous swellings and degeneration in the feet and hands, has
been ascribed to a parasitic Fungus, named by Berkeley Chionyphe Carteri!. More
thorough investigation has shown that it is at least doubtful whether there is any causal
connection between the disease and the growth of a Fungus. Fungus-elements are
found, but not invariably according to more recent accounts, in the swellings, and there
is no ground whatever for supposing it to belong to the form obtained by cultivation on
rice-pap which bears the name of Chionyphe. It is hard to say what this Chionyphe
itself is.

The often described occurrence of Fungi in eggs is a special case of saprophytic
vegetation, and is not therefore one for consideration here.

PaRASITES ON PLANTs.
a. Facultative parasites.

Section CVIII. Parasites on plants display much greater variety in their
adaptations to their peculiar mode of life than those which live on animals.

A quite gradual passage from saprophytes to parasites is effected especially by
the facultative parasitism of certain saprophytic Moulds which cause rottenness in
orchard fruits; the softening of pears, it should be observed, is not due to the
action of a Fungus. These phenomena were investigated by Davaine? in 1866, and

* H. J. Carter, in Ann. mag. nat. Hist. IX (1862), p. 442, and in Journ. Linn. Soc. VIII, 1865.
M. J. Berkeley, in Jourri. Linn. Soc. VIII, 1865.

H. V. Carter, Mycetoma or the fungus disease of India, London 1874.

Hirsch in Virchow’s and Hirsch’s Med. Jahresber. X, 1 (1875), p. 437, XI, 1 (1876), p. 382.
Lewis and Cunningham, The Fungus Disease of India, Calcutta 1875.

2 Recherches sur la pourriture des fruits (Comptes rend. 83, pp. 277, 344):

380 DIVISION III.—MODE OF LIFE OF THE FUNGI.

afterwards by Brefeld’. Species of Mucor (M. stolonifer and M. racemosus), Penicillium
glaucum, Trichothecium roseum, and other species are able to make their way into sound
juicy fruits, and vegetate and cause rottenness in them. These do not rot without the
Fungi. If spores are sown on the uninjured surface of thick-skinned fruits like the
apple and pear, where there is sufficient moisture for germination, the germ-tubes are
unable to penetrate into them or do so with difficulty ; but they enter with ease if the
spores are sprinkled on wounded places where the skin is broken. Mycelia which have
already acquired some strength are better able to force their way through the unbroken
skin. The softer the fruits have become from other causes the more easily are they
penetrated by the Fungus ; fruits therefore like strawberries and raspberries with thin
skins are very liable to be attacked. Davaine found that the vegetative organs of
succulent plants, such as Sempervivum, Mesembryanthemum, and Stapelia show the
same phenomena as thick-skinned fruits. Observation of the fruits shows that the
Fungi develope more easily the nearer the vital powers of the parts attacked are to
their lower limit, and at this point the conditions of saprophytic vegetation make
their appearance.

The parasitic phase of vegetative life is seen in its more characteristic form in
many other facultative parasites on plants, and with many shades of difference in
different species. The Sclerotinieae, Pythieae, Nectrieae, and Hartig’s tree-
destroying Hymenomycetes may be taken as examples for closer consideration.
Many other Fungi, species of Pleospora and Cladosporium for example and allied
forms will have to be added to this if the group is more thoroughly investigated.

Of the Sclerotinieae, Sclerotinia Sclerotiorum (see pages 30, 52, 218) may go
through the whole course of its development as a saprophyte and finds opportunity
for this in the natural state on dead plants. But it can also attack certain living and
healthy plants and parts of plants as a parasite and destroy them. But according to
our present experience it always requires to go through a previous stage of existence
as a saprohyte in order to be capable of parasitism. The allied 8. ciborioides which
preys on clover behaves in a similar manner.

Sclerotinia Fuckeliana inclines more in the direction of saprophytism; both
the mycelia which produce gonidia and those which form sclerotia are found chiefly in
dead parts of plants, especially on decaying leaves, &c. At the same time it is one of
the chief agents in the production of decay in juicy fruits, and more thorough investi-
gation will confirm the experience drawn from every conservatory, that the mycelium
when it has once reached a certain degree of strength becomes parasitic on living plants
and kills them.

I have previously? given a very imperfect account of the circumstances connected
with the vegetation of Peziza Sclerotiorum, and at that time I also misunderstood to
some extent the facts which were stated about it. More recent observations have given
me a clearer understanding of the matter and it will be well to describe them here in
greater detail. The ripe ascospores germinate in pure water, emitting short tubes which
soon cease from further development ; in a suitable nutrient solution, in must of grapes for
instance and onripe juicy berries of any kind, they develope into a vigorous mycelium
which forms sclerotia, and the same result is obtained if they are sown on dead vegetable

1 Sitzgber. d. Naturf. Freunde zu Berlin, Dec. 21, 1875. See Bot. Ztg. 1876, p. 281.
? See the first Edition of this work, p. 215.

CHAPTER VII. —PHENOMENA OF VEGETATION.—PARASITES. 3 81

substances, and even according to Brefeld on bread. Ifthe spores for example are sown
on a piece of carrot which has been killed by hot water, a vigorous fungal growth
is obtained ; but on the moist surface of living portions of the same plant only short
germ-tubes are produced, as in simple water, and these do not penetrate into the living
tissue, even where the surface has been injured ; the parts which have been sown
remain for weeks free from the Fungus. If on the contrary the infection of the sound
part is due to germ-tubes which have developed to a small amount only in a nutrient
solution—how much cannot be exactly stated, but it is sufficient if the germ tubes are
scarcely visible to the naked eye,—they penetrate at once into the living tissue and kill
it, and form mycelium and sclerotia; pieces of older mycelium behave in the same way.
The results are obtained with all parts of the plant, according as they are alive or dead
and are inoculated with spores or with germ-tubes which have reached a certain stage
of development. I never saw a germ-tube make its way into living tissue without
having been previously nourished as a saprophyte; some statements to the contrary
will be noticed in the sequel.

But Sclerotinia Sclerotiorum is also found as a parasite on living cultivated plants, not
to mention the injury which it does to turnips in store. I observed it destroy the beans
(varieties of Phaseolus vulgaris) in a garden in the neighbourhood of Bregenz two years
successively, and a similar occurrence has been reported recently by Prillieux from
Algeria’. It is also very fond of attacking Zinnia elegans and the Petunias. If we try
to infect sound specimens of these favourite species, even quite young seedlings, with
spores which are germinating in pure water, we always get the same negative result as
in the carrot; the plants remain uninjured. If an extremely small amount of some
nutrient solution is supplied to the germ-tubes emitted by the spores they at once
become strong enough to penetrate into the plants at any place and then to develope into
a mycelium which will spread through them and destroy them and form sclerotia, unless
the amount of food which it obtains is insufficient, as in the case of seedlings. The
same results were obtained with older vigorous mycelia. In the case of plants growing
naturally and rooted in the soil we can see how the Fungus as a rule makes its way
into the stem from the surface of the ground, and leaving the roots untouched ascends
in the tissue of the aerial parts, especially in the masses of parenchyma. In this way
the whole plant is killed and dried up and becomes of a pale straw colour. During this
process it is not necessary for the Fungus to appear on the surface ; in fact it often re-
mains quite inside and then forms its sclerotia in the shape of cylindrical or prismatic
bodies inside the dead pith especially in the neighbourhood of the nodes, or, as in
Phaseolus, in the fruits also between the ovules ; in Zinnia it often fills the receptacle with
a sclerotium which like it is conical in shape. In a very moist environment however the
mycelium may come out to the surface of the plant which it has attacked in smaller or
larger quantity in white flakes and tufts, and can also form its sclerotia there ; it may
also pass over to the foliage of neighbouring plants with which it comes into contact,
and destroy them, proceeding from above downwards. This may be observed in a very
striking manner where beans stand close together in a plot.

All these phenomena may easily be reproduced by artificial cultivation in pots. It is
only necessary to place some mycelium, grown from spores and made capable of infec-
tion in the way described above, at the base of the plant to be infected, and keep the
whole sufficiently moist. Experiments have shown that commencements of mycelia
capable of infecting other plants may be obtained from spores on a small bit of dead
vegetable substance, a piece for instance of a dead leaf. The mycelia therefore may be
formed on every bit of moist ground covered with vegetation to which the spores find
their way. Sporocarps formed spontaneously from sclerotia of the previous year were

.to be found in the bean-garden just spoken of, and these supplied the spores.
As a saprophyte the Fungus developes on all dead parts of plants employed in

1 Comptes rend. 99 (1882), p. 1368,

382 DIVISION III,—MODE OF LIFE OF THE FUNGI.

its cultivation, though they may supply unequal amounts of nutrient material. On the
other hand it by no means attacks every kind of Phanerogam as a parasite. I was
unable to find, after repeated and careful search, any trace of the Fungus on the plants
of a moist meadow close to the beans above mentioned. Among plants under cultiva-
tion one variety of Phaseolus vulgaris in the same garden was very slightly infected
with the Fungus in spite of the immediate proximity of the others. Experiments
in inoculation also showed that Phaseolus multiflorus was scarcely ever attacked ; in
other specimens the Fungus developed only scantily, but in single young seedlings kept
very moist its growth was vigorous. Living plants of Brassica (B. rapa, B. Napus,
and B. oleracea) were never attacked, either as young seedlings or as plants ready to
blossom. Further details must be reserved for another place.

It should be added, that the hyphae of the Fungus when once they have become
capable of infecting make their way into the superficial living cells by piercing their
walls, and grow indiscriminately in and between and through the cells of the living
tissue and soon kill them. The power of infecting is shown by the power of penetrating
the membranes, which are evidently dissolved at the points of penetration. Hence it
is very probable that this power depends on the presence of a substance which can
dissolve a membrane, a ferment in fact, and that this substance is not formed and
discharged in sufficient quantity till the germ-tube from the spore is properly nourished
and developed.

The foregoing statements with regard to the power possessed by Sclerotinia Sclerotiorum
of infecting are in opposition to some which have been published in other works and
especially in Frank’s Pflanzenpathologie, p. 530 ff. ; according to these accounts the young
germ-tube has the infecting power without previous preparation, and plants of Brassica
were at once attacked by the Fungus. The observations may be correct in both cases
and the difference may arise from the fact, that several species resembling one another
in ‘appearance, but differing in the mode of vegetation, are confounded together under
the name of Sclerotinia Sclerotiorum. The discussion of this point would occupy us
too long and must be reserved for another occasion.

Among other species of Pythium' which have been carefully examined Hesse’s P.
de Baryanum is a parasite on living and healthy plants, and attacks them both with
its germ-tubes which are formed in water and with the branches of the mycelium,
when it has acquired strength. It attains its full development equally well on dead
vegetable substances and on the dead bodies of animals, and is therefore equally a-
saprophyte and a parasite. In the latter character it penetrates into the cells of a
great variety of Dicotyledons and Monocotyledons and into the prothallia of Ferns,
but leaves plants of Spirogyra and Vaucheria untouched. Some Phanerogams are
also said to be secure from its assaults, but this statement requires confirmation. It
attacks with especial readiness and frequency the young and watery seedlings of
Phanerogams such as the Cruciferae and Amarantus, taking possession of them and
destroying them rapidly and completely. Full-grown land-plants are usually less readily
attacked and the injury done to them is more local; but they too may be rapidly
destroyed by the Fungus if they are placed in water.

Other and nearly allied species of Pythium are, as far as is known, partly pure-
saprophytes, partly facultative parasites within narrow limits, P. intermedium and
P. megalacanthum grow as saprophytes on dead parts of plants. They leave living
Phanerogams, even young seedlings which are so liable to the attacks of P. de Bary-
anum, always and absolutely untouched ; but P. intermedium readily attacks the

1 Bot. Ztg. 1881, p. 531.

CHAPTER VII.—PHENOMENA OF VEGETATION.—PARASITES. 383

prothallia of Ferns and quickly kills them, while P. megalacanthum was only
rarely induced to penetrate into them, and its development in them was slow.

Nectria cinnabarina' is one of the most common saprophytes on dead twigs.
Their bright red cushions burst forth in abundance from the rind of branches which
have been killed by frost in the previous winter. Their germ-tubes do not attack the
surface of living branches, or living rind or bast tissue when laid bare. But if
they find their way to a wounded surface where the wood is exposed, they penetrate
into it, and the mycelium grows rapidly upwards in the vessels, causing decomposi-
tion of the wood-substance ; this is followed by the death of larger or smaller portions
of a branch or stem, and the further development and the formation of perithecia
by the Fungus then takes place in the dead rind. This at least is the course of
proceeding in Acer, Tilia, and Aesculus. Other woods gave an uncertain or negative
result.

Nectria Cucurbitula, Fr.? developes a mycelium producing gonidia when raised
from spores in a nutrient solution. It is uncertain whether this species can arrive at
the formation of perithecia in this saprophytic mode of life. But its germ-tubes
penetrate through wounds in the Zvzng rind of pines into the living tissue, and spread
rapidly through it during successive periods of vegetation, covering a distance of
ıo cm. in the longitudinal direction in one season; they at last kill the tissues
which they have attacked and then form perithecia which come out upon the surface.
This highly pernicious Fungus usually makes its attack where wounds have been
caused by hail-stones or by fractures under a weight of snow, and especially where
the bark has been eaten away by Grapholitha pactolana.

Nectria ditissima, Tul., the Fungus which causes canker in deciduous trees
especially in the apple-tree®, agrees closely with N. Cucurbitula as regards the arrange-
ments which have been described. The Fungus penetrates at some injured spot into
the living rind and spreads slowly in it and also in the adjoining wood; the parts
attacked are dried up and destroyed so far as they consist of juicy tissue, while
cushion-like formations appear all round them advancing centrifugally in successive
periods of vegetation ; in consequence of these and of the successive partial drying up
of the parts, malformations are produced in the shape of swollen places with a
depressed dead centre, which themselves also in course of time partially die away.
Gonidia and perithecia emerge from the periderm at the margin of these swollen
places where the tissue is still succulent.

The wood-destroying Hymenomycetes occupy a prominent position among
facultative parasites. Agaricus melleus may be taken first as a typical example of this
group. We know from Hartig’s researches supplemented by Brefeld that the spores
of this plant germinate on dead vegetable substances and produce the mycelium which
is characterised by its strands or rhizomorphous form. This mycelium may
develope spontaneously as a saprophyte and bear sporophores in and on dead wood,

‘ H. Mayr, Ueber d. Parasitismus v. Nectria cinnabarina (Unters. a. d. Forstbot. Instit. z,
Miinchen, III).

2 R. Hartig, Unters. a. d. Forstbot. Instit. z. München, I, p. 88.

5 R. Hartig, 1. c. I, 109.—R. Göthe in Thiel’s Landw. Jahrb. IX (1880), p. 837.

384 DIVISION III—-MODE OF LIFE OF THE FUNGI,

trunks of trees, wooden conduit-pipes, &c. But the strands also make their way from
the soil through the uninjured living rind into the roots of healthy living trees, especially
our Coniferae; there they destroy the inner rind and then grow at its expense into the
subcortical expansions described above, from which hyphae push on further through
the medullary rays into the wood. While the mycelium is spreading at these spots
and mounting in the stem, it kills the living tissue and ultimately the whole tree. The
propagation of the Fungus from tree to tree by means of the mycelial strands
spreading far and wide in the soil has been already described. ‘The symptoms of
disease which precede death in fir-trees are known as ‘resin-flux’) (‘ Harzsticken,
Harziiberfiille’) and the phenomena attending the decomposition of the wood, which
advances with the spread of the Fungus, should be learnt from Hartig’s excellent
descriptions?,

Trametes radiciperda of Hartig (Polyporus annosus, Fr)., which attacks the
wood of fir-trees from the roots and kills it, comes nearest to Agaricus melleus in its
mode of life and operation, but it has not the rhizomorphous strands. The
filamentous mycelium penetrates from without into the uninjured rind of the roots,
whether it has developed directly from the spores or, as is most conducive to
the spreading of the Fungus, has grown out of an infected root in moist soil and
has encountered a sound root in contact with the first. It has been observed to put
out germ-tubes capable of infecting in less than twenty-four hours in a moist environ-
ment. Whether it can arrive at its full development when growing as a pure
saprophyte on dead wood is still uncertain, but according to some observations of
Hartig it is probable ; at any rate it would appear to be adapted rather for strict than
for facultative parasitism.

R. Hartig has also made us acquainted with a number of other Hymenomycetes
which produce decompositions of the wood of living trees in forms varying with each
species, and thus kill the plants; Trametes Pini, Polyporus fulvus, P. vaporarius,
P. mollis, and P. borealis in fir-trees ; Hydnum diversidens, Thelephora Perdix, Poly-
porus sulphureus, P. igniarius, P. dryadeus, and Stereum hirsutum in the oak. It is
probable that there are many cther wood-destroying Fungi which approach the above
in the qualities just indicated.

All these Fungi attack the wood from places exposed by wounds and do not
penetrate into it through the uninjured rind, with the exception of Polyporus mollis,
in which this point has not yet been cleared up.

It is probable therefore that they are fed and made capable of infecting chiefly
by the products of the decomposition of the superficial wound-layers which have
been laid bare and killed, in the same way therefore as the Sclerotinieae are facultative
parasites; but no satisfactory experiments have been made to ascertain this point.
On the other hand it is tolerably certain that Stereum hirsutum often attains to its
perfect development as a saprophyte in dead wood. We have no certain knowledge
on this point in the case of the other species which have been named.

1 [There appears to be in use no English equivalent of the expression Harzsticke and Harzüber-
fülle; the word resin-finx is therefore introduced as indicating a prominent symptom of the disease,
although it is not an exact rendering of the German terms.]

? See above, page 23.

CHAPTER VII,—PHENOMENA OF VEGETATION,—PARASITES, 385

&. Obligate Parasites.

Section CIX. Most of the groups described in Chap. V contain a large
number of Fungi which are obligate parasites, as will be seen by reference to the
accounts there given; but within the class itself we meet with every gradation of
adaptation, from the strictly parasitic mode of life to arrangements in which we may
almost as well speak of facultative parasites, as of obligate parasites which are at
the same time facultative saprophytes. Phytophthora omnivora' in the group
of the Peronosporeae well exemplifies the transition from facultative parasitism.
This Fungus is a destructive endophyte in many kinds of living Phanerogams, as
Fagus and especially in young seedlings, in Sempervivum, the Oenothereae, and
others. Other species of Phanerogams it leaves uninjured, as Solanum tuberosum
particularly and Lycopersicum. Its development is rapid in proportion to the amount
of water contained in the host, even when that amount exceeds the limits of a
normal and sound state of the plant and becomes pathological, as when the land-
plants just named are immersed in water. The development of the Fungus culminates
in the formation of oospores, usually in large numbers, after the host has been killed
by its assailant. The Fungus can also grow on dead organic, even animal,
bodies in water and form an abundance of gonidia, but without arriving, as far as is
known, at the formation of oospores. On this latter account it is better to place it
among facultative saprophytes. The same may be said of its nearest relative Phy-
tophthora infestans the Fungus of the potato-disease, with the limitation that the
adaptation to a parasitic mode of life is more marked.

For the same reasons the members of the Mucorini, Piptocephalis, Synce-
phalis, and Chaetocladium, to which the expression facultative parasites was first
applied, may be termed facultative saprophytes. They may be grown as saprophytes
from spores in a nutrient solution and produce an abundance of gonidia, but accofding
to present observations they only attain to their full development in the formation of
zygospores when they live as parasites on other Mucorini in the manner described in
a former page.

The species also of the Ustilagineae (see page 179), in which the young plants
can vegetate by sprouting or in the manner of the Hyphomycetes in solutions made
from organic bodies, must be termed facultative saprophytes. But the saprophytic
faculty is much less important to them than the parasitic mode of life, for it is as
parasites only that they are able to produce the resting spores and sporophores
which are peculiarly characteristic of their development. This is so, even if the round
cells of intercalary origin obtained by Brefeld’ in large quantities from the mycelium
of Tilletia Caries, when it is grown as a saprophyte in nutrient solutions, really
have the characters of resting-spores; this can only be proved by observing their
germination, and in default of this observation it remains unproved; moreover the
characteristic sculpture on the surface of the spore-membrane of T. caries ‘could not
be clearly seen’ on the products of cultivation. In the majority of the species
which have been examined the saprophytic development does not go beyond the

1 Bot. Ztg. 1881, p. 585.
2 Hefepilze, p. 159.

[4] a

386 DIVISION III. —MODE OF LIFE OF THE FUNGI.

production of gonidia; and it may be assumed, though it has not been yet distinctly
proved, that they may form germs capable of infecting, and that by means ofthese germs
they attack the host-plant and thus return to a parasitic life, somewhat in the way
described at page 373 in the case of Cordyceps.

The facts stated in pages 265, 339 show that the behaviour of Exoascus and
Exobasidium is quite similar to that of the Ustilagineae.

The example of Cordyceps leads to the mention of Claviceps, and Epichloe
typhina also approaches near to the latter genus in the points in question. The
gonidia (and possibly also the ascospores) of these Fungi may develope small mycelia
producing fresh gonidia in the manner described on page 227. That this facultative
saprophytism in its various degrees is a frequently recurring phenomenon in parasitic
Ascomycetes is to be expected, though more stringent proof of it is in most cases
still to be desired.

Of all the Ascomycetes the Lichen-fungi, according to our present knowledge,
must be mentioned first as examples of strictly obligate parasites, after them the
Erysipheae and Polystigma (section LXIII). It has still to be ascertained what are
the exact conditions in this respect in the large number of parasites in the groups
of the Hysterineae and Phacidieae. The Peronosporeae also contain excellent
examples of the class which we are considering, for most species of Peronospora
and all of Cystopus are strictly parasitic, the first stages only of germination being
completed outside the host. This is the case also with Protomyces and many Chy-
tridieae, some of which even commence germination on the surface of the host
(see Chapter V). Lastly, only the strictest parasitism is known in the group of the
Uredineae so rich in forms; they germinate if sufficiently supplied with water, and
their further development takes place only on the proper host.

Section CX. The Fungi which are parasitic on plants naturally exhibit within
the limits of the chief phenomena of parasitic vegetaticn and its effects, which were
pointed out on page 359, a variety of special adaptations in respect of their choice
of a host and their spreading in, upon, or along with it. The reaction of the host itself
which varies in each case corresponds again to the spread of the Fungus. We call
attention to the following facts which are of general interest in relation to these
points, again referring the reader to the former sections of this work and to the
special literature of the subject.

As regards the choice of the species to serve as a host, the rules stated on
page 359 are of the first importance. Most parasites living on plants require a single
proper host for the completion of their whole course of development, though they may
enjoy a larger or smaller room for choice between different species more or less nearly
allied to one another. Of all the hosts that are possible for a species of Fungus some
may be more favourable to their development than others. Cystopus cubicus for
example flourishes and forms abundance of gonidia on the leaves of species of Trago-
pogon, Podospermum, and Scorzonera, but forms oospores almost exclusively on
Scorzonera, especially on S. hispanica; oospores are extremely rare on Tragopogon
in my experience. So it is with the Uredineae and species of Erysiphe. The best
known Erysiphe is the Fungus of our grape-vine' which in Europe only forms gonidia

1 See De Bary u. Woronin, Beitr. III.

CHAPTER VII.—PHENOMENA OF VEGETATION.-—PARASITES. 387

(Oidium Tuckeri, Brk.); its sporocarps are perhaps the objects described as Uncinula
spiralis, which grow in North America on a native vine. This dissimilar promotion
by hosts of different species of the otherwise similar course of development of the
Fungus makes no difference in the phenomena in question. Parasites which go through
their whole course of development on a single host of a particular species are termed
auloecious or autoxenous. All the parasites described in preceding chapters are examples
of this class, with the exception of one group to be named presently. It is not perhaps
altogether superfluous to remark, that the larger part, or at any rate very many species,
of the Uredineae, in which the alternation of generations is most copiously differ-
entiated, are autoecious.

Thus the entire development of Uromyces Phaseolorum is completed on species
of Phaseolus, that of U. appendiculatus on the Vicieae, of Puccinia Tragopogonis on
Tragopogon, of P. Pimpinellae on Myrrhis or Chaerophyllum, of P. Falcariae on
Falcaria Rivini, of P. Violarum on species of Viola, and so on.

The contrary is the case with a number of Uredineae which form aecidia. These
are obliged to change their host with the separate sections of their alternating genera-
tions in order to complete the course of their development, like the Cestodes and
other parasitic worms. They are accordingly termed hefercecious, or still better
meloecious or meloxenous as changing their place of-habitation or host}.

I was myself the first to establish this metoecism in the case of Puccinia graminis,
in which the phenomenon or at least its consequences were recognised more than a
hundred years ago by agriculturists, who rightly maintained against the botanists that
grain grown in the neighbourhood of shrubs of Berberis were liable to be attacked by
rust, that is by Puccinia graminis. This parasite exhibits the pleomorphism and
alternation of generations of the Uredineae which form aecidia in its greatest variety of
form (see page 279). Its teleutospores pass the winter on old stems of wild and
cultivated grasses, especially Triticum repens, while the germ-tubes from the sporidia
which are developed in the ensuing spring penetrate into the epidermal cells of
Berberis vulgaris, more rarely into those of a Mahonia, and never into a grass. They
develope rapidly in Berberis into a mycelium which produces aecidia but never forms
uredospores or teleutospores, and if the germ-tubes of the aecidiospores find their way
into the stomata of suitable Gramineae they develope there and there only into a
mycelium which produces uredospores and teleutospores. The germ-tubes of the
uredospores in their turn develope only on the Gramineae, and in the manner which
is common to all uredospores.

Later investigations have shown that an analogous change of hosts takes place in
many other species.

The aecidiaof Puccinia Rubigo vera and P. coronata which also live on Gramineae
or Cyperaceae in the other sections of their development are confined, the former to the
Boragineae, the latter to species of Rhamnus; those of P. Moliniae to Orchis; those
of P. Caricis to Urtica and of P. (Caricis) limosae to Lysimachia thyrsiflora ; Uromyces
Dactylidis forms its aecidia on the leaves of common species of Ranunculus’, and its

1 See on the terminology Bot. Ztg. 1867, p. 264; on other points see the literature of the Uredineae
enumerated above on page 286.
2 See also Cornu, Comptes rend. 1882, 94, p. 1731.

cc 2

388 DIVISION III-—MODE OF LIFE OF THE FUNGI.

uredospores and teleutospores on Gramineae; Uromyces Pisi forms uredospores
and teleutospores on Vicieae and its aecidia on Euphorbia Cyparissias, the well-known
Euphorbia-aecidium. Next to these species all the Gymnosporangieae are examples
of the phenomenon in question, as Oersted was the first to show from gardeners’
traditions; their teleutospore-layers inhabit species of Juniperus, and migrate to Pyrus
and other Pomaceae for the formation of aecidia, which were once known by the
name of Roestelia. The aecidia of several species which live on the Ericaceae are
formed on leaves of the Abietineae which are entering their first year, those of
Melampsora Géppertiana, as Hartig showed, on Abies pectinata ; those of Chrysomyxa
Rhododendri, the Fungus of the alpine rose, and of C. Ledi on the spruce, Abies
excelsa. The Coleosporium of species of Senecio migrates according to Wolff to the
leaves of Pinus sylvestris, and there produces its aecidia which were known by the old
name of Peridermium Pini. The rest of the known cases of the kind will be found
collected together in Winter’s Pilzfiora.

The same work also enumerates the forms bearing teleutospores and those
bearing aecidia, of which it is known that the germs which are capable of infecting do
not proceed to further development on the hosts on which the forms themselves
grew. The aecidia-forms never propagate themselves on their hosts; teleutospore-
forms are produced only in certain circumstances through the medium of the
uredospores which accompany the teleutospores. From the analogy of the cases in
which metoecism is certainly known these forms must be separate sections in the
development of metoecious species. Their complete form-cycle has yet to be
ascertained. To this group belong on the one hand most of the species of Melam-
psora and Coleosporium, the Cronartieae and also Hemileia vastatrix, the Fungus of
the coffee-plant, on the other the aecidia of fir-cones, the aecidium known as Peri-
dermium elatinum which causes the ‘witches’ brooms’ in Abies pectinata (see
page 368), the aecidium of species of Clematis, and many others.

Metoecism, that is, enforced change of the living host, is not known outside the
group of the Uredineae ; its supposed occurrence in other species has not yet been
confirmed. There is another phenomenon which must of course be kept quite distinct
from it, and which may be termed /foxeny or deserting the host in opposition to
a change of the host. Many Fungi which inhabit plants spend a certain period of
their life in strictly parasitical fashion on the host, and then separate from it and
complete the other sections of their development independently without a living host,
and entirely at the expense of the reserve of food which they have appropriated from
the host. The separated thallus may be compared as regards the economy of the
metabolism to a ripe spore which is able to germinate at the expense of the reserve of
food which it contains. This phenomenon is most striking in Claviceps which
continues strictly parasitic up to the ripening of its sclerotia, and produces the stromata
from them after they have fallen from the plant under favourable conditions of temper-
ature and supply of water in the next period of vegetation (see on page 227). A similar
course of events may take place in Peziza Durieuana which forms its sclerotia
on stems of Carex, and Peziza Curreyana which forms them on stems of Juncus
and Scirpus, and produces ascocarps from them in the next period of vege-
tation, The Sclerotinieae may also be mentioned in this connection ; and the long
series of Ascomycetes which inhabit leaves, such as Polystigma, Rhytisma, Phyllachora,

CHAPTER VII—PHENOMENA OF VEGETATION.—PARASITES, 389

Phacidium &c., must be added to the list,— species which commence their vegetation
on the living leaf, and complete their development by forming their sporocarps on
it when fallen and decayed in the next period of vegetation, and here too at the
expense of the reserve of food obtained from the living host. How far the building-
material required for the last section of the life of the plant is partly taken from the
dead decaying leaf has never been thoroughly investigated and can scarcely be
determined with entire certainty. But this supply of material can be at most only a
small addition, since on the one hand the Fungus-body, separated from the sur-
rounding substance of the fallen leaf, also reaches its normal and complete develop-
ment, and on the other hand it can be seen directly that the reserve material. stored
up in the Fungus-body is used up in the course of this development. It is possible
that in this case also intermediate forms and shades of difference may occur, in which
a final stage of enforced saprophytism succeeds the parasitic vegetation, in the way
described above on page 373 in the case of Cordyceps.

Section CXI. The purely local circumstances connected with the spread of
parasites on plants from the place of attack need no further discussion in the case of
hosts formed of one or few cells, because the parasite must necessarily remain
narrowly localised in and on so small a body; and the remark equally applies to
those which like the Synchytrieae live in single cells of larger plants.

Parasites which form mycelia in more highly organised and especially in
phanerogamous plants behave very differently according to the species or to the
segment of their development; in the one extreme they are confined to the immediate
neighbourhood of the point of attack, in the other they spread wrdely or unlimitedly from
that point over or through the host.

From among the many species which have been noticed from time to time in
former sections of this book and in addition to them, we may name here as examples
of the first category the parasites which form narrowly circumscribed spots on the
leaves of Phanerogams, such as many Uredineae, and among them Puccinia graminis,
P. Rubigo vera, Uromyces Phaseolorum, Peronospora viticola and P. nivea (Umbelli-
ferarum), Protomyces macrosporus, Entyloma Calendulae, species of Polystigma and
Rhytisma. Each distinct spot inhabited by the Fungus is the result of the growth of
one or occasionally of several spores. Fresh spots are added one after another on a
surface in: proportion as new spores from any quarter, for instance from those first
established on the leaf, germinate there and assail it. The species of Claviceps are
confined to the flowers of Gramineae and Cyperaceae during the whole of the
parasitic portion of their life, and destroy the young ovary in the manner described
above. The germ-tube of one spore at least is required to infect each ovary, and it
attacks the ovary directly.

Among the Fungi of the second category which spread far from the point of
attack are the often mentioned Sclerotinieae, Pythieae and Phytophthora, which
assail the host at any point and grow through it to an unlimited extent in every
direction, provided the external conditions are favourable. Cystopus candidus is
instructive as an instance of strictly obligate parasitism. Its germ-tubes find their
way into every stoma in Lepidium sativum and Capsella on which germinating spores
fall (page 363). But those germs only develope further which have penetrated into
the cotyledons, and the mycelium may spread from them through the entire host as

39° DIVISION I1I.—MODE OF LIFE OF THE FUNGI.

it developes and form a multitude of gonidia on it. These gonidia cannot attack
plants when once they have lost their cotyledons. Hence when a number of these
plants are growing together, some are often found thickly covered with Cystopus
and surrounded by others of the same age which are quite untouched by the
Fungus.

Endophyllum Sempervivi makes its way in spring into any leaf of the host,
spreads through all parts of the plant and produces its aecidia in the succeeding
spring in the younger of the leaves which have lived through the winter, and may
then persist for years in the same state of diffusion in a rosette of leaves, forming
fresh aecidia every spring. The spot where Endophyll m Euphorbiae enters its host
has been mentioned on page 364 ; the mycelium spreads from there through the entire
plant and produces aecidia in the young leaves of the next year, producing deformities
in their petioles. Melampsora Géppertiana penetrates in summer into the shoots of
Vaccinium Vitis-Idaea, and its mycelium spreads through the parenchyma but does
not deform it. After the succeeding spring it enters every year into the new terminal
and lateral branches from the infected shoot, causing peculiar deformities in them,
and forms its teleutospores not in the epidermis of the leaves but in that of the stem’.

Kiihn and R. Wolff have shown that the germs from the sporidia of many
Ustilagineae which attack grasses penetrate into the host when it is young and
germinating, sometimes into the first sheathing leaf, sometimes into the lowest node
of the young stem and even into the base of the young roots. The mycelium then
grows with the growing stem and its lateral shoots, and at length makes its way into
the organs in which the Fungus prefers to produce its sporophores, and consumes
them and forms its spores. The mycelium which has grown with the growing internodes
is not entirely destroyed when the elongation is completed; intercellular branches are
preserved in the nodes, and these send new branches into the axillary buds which
may be produced at the nodes, to repeat the process of growth already described.

We are acquainted with a number of endophytic parasites, which so far resemble
those last described in their behaviour, that their mycelium spreads through large
portions of the host and then produces its sporophores in or at certain spots, and
this may happen once only, or is repeated every year from the perennial mycelium in
new branches and leaves, &c. Though the act of entering the host has not been
observed in these cases, there can be no doubt that the circumstances are quite or
nearly the same as those which are certainly known either in Endophyllum, or
in’ the Ustilagineae which have just been described. Among these forms are most
of the remaining Ustilagineae, the Aecidium of Euphorbia Cyparissias, the Peridermium
elatinum of the ‘witches’ brooms’ of Abies pectinata, the Exoasci which also form
‘witches’ brooms,’ Peronospora Radii of Pyrethrum inodorum and Peronospora
violacea, Brk. of Knautia arvensis which produce spores only in the flowers of the host,
Epichloe typhina which lives on the Gramineae and many others.

Species in which the segments of their development differ from one another and
stand to one another in the relation of alternate generations spread in the host in the
same or in a different manner in the different segments. The first is the case for
example in the Uredineae which have been already adduced as examples of narrow

! Hartig, Lehrbuch d. Baumkrankheiten, p. 56.

CHAPTER VII,—PHENOMENA OF VEGETATION.-—-PARASITES, 391

localisation. Other species partly belonging to the same genera show the opposite
behaviour. The mycelium of Puccinia Tragopogonis which bears aecidia for instance,
spreads all through the host and produces its aecidia over the entire surface of the leaves,
while that which grows from the aecidiospores and forms teleutospores is confined
to small spots on the leaf. The same is the case also with Uromyces Pisi, the con-
verse with Melampsora Géppertiana.

The varying extent to which Tuburcinia Trientalis spreads (see page 180)
according to the kind of spore from which it grows is a nearly allied phe-
nomenon.

But mycelia grown from similar spores appear in some cases to be narrowly
localised or to spread widely according to the species of the host. Cystopus candidus
for example often appears to be limited to narrow spots in the leaves of species of
Brassica, into which it must have penetrated through the stomata of the full-grown
leaves, while it behaves in exactly the opposite way in Capsella and Lepidium. Its
mode of entrance in Brassica would be in accordance with experience, for I once
observed that the germ-tubes of this Fungus were able to develope a mycelium in the
full-grown leaves of Heliophila crithmifolia. It isnot improbable that some Uredineae
are affected in the same way by a difference in their hosts, but the point requires
further examination.

In many Fungi the mycelia which spread through the host have everywhere
the same characters, or at least they have no distinct and special characters at distinct
places in the host; they may form their spores at any spots where the external
conditions, as supply of air or peculiar mechanical relations, permit, and actually do
so form them.

On the other hand there are many species which assume different characters
in different organs of the host, showing structural differences in the hyphae themselves,
and especially capacity or incapacity for forming sporocarps and spores. It is obvious
that conditions of nutrition must in general be the cause of this phenomenon, but we
have at present no precise physiological account of the matter. We can only therefore
speak provisionally in such cases of favourite places for the formation of one and
another kind of spore. Some remarkable examples have been already briefly given
in Chapter V, but we may add a few more in this place.

Cystopus Bliti forms its gonidia only on the leaves of Amarantus Bliti, and its
oospores only in the stems; Cystopus candidus forms gonidia in great abundance on
all the aerial organs of its hosts, but I never found its oospores on the leaves; some
species of Peronospora behave in the same way; P. Arenariae, Brk., for example,
produces gonidia on all parts of the leaves of Möhringia trinervia, oospores almost
exclusively in the parts of the flowers. Very many Ustilagineae form their spores only
in or on the parts of the flowers of the host, some in the anthers, others in the ovary
or ovule, others again (Sorosporium Saponariae, Ustilago Tragopogonis) on the whole
surface of the corolla and of the parts inclosed by it. It has already been remarked
that Peronospora Radii and P. violacea are also confined to the flowers of the host for
the formation both of oospores and gonidia. In other Ustilagineae, as Urocystis
occulta, certain parts of the leaves are ihe places where the spores are formed, in
Ustilago hypodites chiefly the surface of the stem where it is covered by the leaf-
sheath. Epichloe typhina always forms its stromata on the outer surface ofthe sheath

392 DIVISION III.—MODE OF LIFE OF THE FUNGI.

of a foliage-leaf which stands underneath an inflorescence, generally the next but one
or two beneath it; the leaf or leaves above it and the inflorescence itself wither away in
consequence.

In this and in almost all the cases of the Peronosporeae and Ustilagineae
which have been mentioned the mycelium spreads through the entire stem
of the plant but cannot be seen in it, and causes no change in it which is visible
from without. A superficial examination only would lead us to suppose that only
the parts chosen for the formation of spores are occupied by the Fungus, and that
the rest of the plant which looks quite healthy is free from it, But in most cases of
the kind all or nearly all the similar parts of a plant where spores are formed by
preference are seen even in their young state to be uniformly occupied by the spore-
forming organs of the Fungus. This enables us to conclude in doubtful cases that
the Fungus is one which is widely spread and not confined to a limited spot, because
in the latter case it scarcely ever happens, for obvious reasons, that all similar young
parts are attacked in this uniform manner.

Secrion CXII. Independently of these coarser phenomena of localisation
the histological distribution, as we may briefly term the behaviour of the Fungus
to the cells and tissues of the host, is also liable to variations in endophytic
parasites on plants and in the endophytic haustoria of parasites which are otherwise
epiphytic. In considering these variations we must of course also keep in view the
reactive influence of the host, which is necessarily connected with them.

In the higher plants. with their various kinds of tissue the wood-destroying
Fungi described at page 383 spread in the tracheal and sclerenchymatous tissues and
destroy them. But most parasites exclusively or almost exclusively affack living cells
containing protoplasm, the parenchyma therefore, soft bast and epidermis, where the
tissues are differentiated, and even the wood-destroying Fungi just named do the
same. Accordingly a number of histological localisations result from conditions such
as have been already described, and further details must be sought in special treatises
on the subject. But as a topic of general interest we must briefly notice the
differences in the behaviour of endophytic parasites to the living cell.

In unicellular hosts an endophyte is necessarily zu/racellular, that is, vegetates
inside the cell. It may also be intracellular in pluricellular tissues, but it may also
spread in the zufercellular spaces, or it may exhibit both modes of distribution. When
its growth is intercellular, it stands of course in the relation of an epiphyte to the
individual cell, and of that we need say no more here. The entry of the parasite
into the cell of the plant or into parts of it takes place in very dissimilar forms and
with very. dissimilar consequences.

To begin with the extreme which lies nearest to the superficial view of the
subject, there are many parasites wkose hyphae penetrate through the membrane
and into the protoplasmic body of the cell, and kill and destroy the latter at once;
examples of such Fungi are seen in all the facultative parasites described above,
Sclerotinia and Pythium and their near allies the Phytophthoreae and others;
Ancylistes is an instance of this in unicellular plants (page 139).

Other parasites also penetrate the membrane of the cells and pass through
them and through the protoplasmic body. But the latter does not at first succumb to
the assault of the parasite, but retains the qualities which it has in the living cell, and is

CHAPTER VII.—PHENOMENA OF VEGETATION.—PARASITES. 393

fenced off from the parasite by a pellicle which forms a close sheath round the intruder.
Assimilation, metabolism, and even growth of the cell continue often for weeks and
months, the latter in some cases longer even than when there is no parasite present. The
cell succumbs comparatively slowly to the influence of the parasite. This pheno-
menon, which again shows many shades of difference in different cases, is everywhere
common, as in the Peronosporeae and Uredineae, in the haustoria of the Erysipheae,
in epidermal cells attacked by Synchytrium, in the Saprolegnieae when attacked by
Olpidiopsis (see on page 166), and some others. Leitgeb in his work on Comple-
toria ! calls attention to this subject, which has often been observed and mentioned.
He finds also in the continued activity of the protoplasmic body when thus attacked
the explanation of the fact, which has likewise been often described, that mycelial
hyphae, which grow transversely through a cell, are enclosed in a sheath of cellulose
which is continued without interruption into the membrane of the cell attached, or
springs from it. This sheath is often developed in a remarkable manner on the
endophytic mycelia of the Ustilagineae ?.

The piercing of the membrane after the Fungus has made its first attack on the
host often begins with an indentation in it, as was described above in page 364 in the
case of the penetration of many germ-tubes. In some cases, as in the club-shaped
haustoria of Peronospora densa*, the indentation is all that is effected; further
investigation of these matters which have hitherto been little regarded may bring to
light other instances of the same kind.

Lastly there are endophytes, whose hyphae do not pierce through the membranes,
but grow in them in the direction of their surface and there ramify. Some species of
Exoascus, according to Sadebeck’s observations noticed above on page 265, spread
in this way all their life long in the outer wall of the epidermis beneath the cuticle of
the parts attacked, which they do not burst through till they form their asci. Other
species, like Exoascus Pruni, behave in a similar way, only their mycelium grows through
the inner tissue into the subcuticular wall, taking its way as is usually said ‘ between
the cells;’ but it would be more correct and more in accordance with known facts
to say in the cell-membranes. The mycelium of Rhytisma Andromedae, which forms
sporocarps, spreads beneath the cuticle in the outer wall of the epidermis in the
same way as that of Exoascus; the mycelia which produce spermogonia of Puccinia
Anemones, of Phragmidium and of some other Uredineae, and, according to Cornu ‘¢,
the mycelium of Cladosporium dendriticum in the fruits of the Pomaceae, pursue a
similar course. These Fungi burst through the cuticle and come to the surface when
they form their spores or spermogonia. The path of the Fungus must really be
intercellular to reach this position in the Uredineae ; how it arrives there in other
cases is not known. In the Fungus which lives in the vine and which I named
Sphaceloma ampelinum, the germ-tubes of the gonidia penetrate into the outer wall
of the epidermis and spread in it beneath the cuticle, which is only burst by the
small tufts of hyphae which grow up vertically to the surface and abjoint fresh gonidia.

* Cited on page 160.

? See R. Wolff, and Fischer v. Waldheim as cited on page 185.
> Ann. d. sc. nat. ser. 4. XX, p. 29.

* Comptes rend. 93 (1881), p. 1162.

394 DIVISION IIL-—MODE OF LIFE OF THE FUNGI.

Later there follows also a penetration of the Fungus into and between the dead and
dying cells of the deeper-lying tissue-layers !.

In connection with this subject it will be well to recall the fact, that the hyphae
of certain Fungi which are parasitic on other Fungi unite with those of the host, and
the two protoplasmic bodies enter into continuity and
coalesce by disappearance of the cell-membrane in such
a manner that there is no longer a clear distinction
between host and parasite. The fact has been ob-
served in Chaetocladium and has been described
above; it probably occurs in other cases also, for ex-
ample in Artotrogus*. The obscure and disputed
phenomena observed in Nyctalis and some other like
cases may perhaps find their explanation in a similar
relation between the two plants.

Section CXIII. The effect which endophytic
and epiphytic plant-parasites exercise on their
host, when they do not at once put an end to its life, is
seen in a richly graduated series of phenomena, from
the slow exhaustion and wasting away of the host to
the characteristic transformations which in extreme
cases even promote the health and growth of the host,
and which take place when certain parasites attack plants
that are sufficiently young and capable of growth.
Examples of the first kind are to be found on all sides
and may be studied in pathological and descriptive
treatises. The first indication of a hypertrophic
transformation may be said to be given by the fact
to which Cornu® has called attention, that spots on
leaves and fruits occupied by such Fungi as Erysiphe

Fic. 166. Species of Saprokgmi. Suttata (Aceris), Cladosporium dendriticum and the
Extremity of a tube attacked and de’ Tjredineae have a more abundant and more persistent

formed by Rozella septigena. The x
upper part is divided by transverse walls. supply of chlorophyll than their neighbours which are

into seven sporangia of Rozella, six of

which 2 are empty, some showing the 1
vote inthe lateral walwherethecore, ‘free from the Fungus. Next to this comes the normal

escaped; the lowest zx is still full of 1 im] 7 1
Sore’? Further down the tube hee accumulation of products of assimilation in cells at-

wich coetain each me tacked by a Fungus which has been already noticed
a ater Coma ig in a former page, and lastly the mycetogenetic growth
hat, Sr. 5, XV. ph 6). Magn. about of the cells themselves and of the tissues which they
compose. For the hypertrophies and transformations
proceeding from the latter cause, so far as they occur in Phanerogams, it is sufficient
to refer to the examples adduced on page 368 and in earlier chapters. We may
however add to them in this place the description of the peculiar transformations
produced in the Saprolegnieae by certain Chytridieae, and especially the one which
results in the formation of the plant-form described as a Lichen.

1 See Bot. Ztg. 1874, and R. Göthe, Ueber d. schwarzen Brenner u. d. Grind d. Reben. Leipzig 1878,
? Bot. Ztg. 1881, p. 575. 3 Comptes rend. 93 (1881).

CHAPTER VII.—PHENOMENA OF VEGETATION.—LICHENS, 395

The Chytridieae of the genera Rozella and Woronina, which were discovered
by Cornu and more thoroughly examined by A. Fischer’, are parasites on the stout
tubes of the Saprolegnieae which are destined to form spores (see Figs. 68 and 69).
Rozella septigena, Cornu lives on species of Saprolegnia. Its swarm-spores are
ellipsoidal in shape and 6-8 » in length, and bore their way into the growing tubes
of Saprolegnia. When a spore has effected an entrance in this way, it remains
visible for a short time in the protoplasm of the tube and then can no longer be
distinguished; it seems to lose its individuality, to distribute itself and be lost in
the protoplasm of the tube. The tube at once swells out as a large quantity
of fresh protoplasm streams into it, and it divides by transverse walls formed
for the most part in basipetal succession into swollen cylindrical or barrel-shaped
segments, which are from two to several times longer than broad (Fig. 166). The
transverse walls are formed in the same way as in the delimitation of sporangia
in Saprolegnia. Then the protoplasm in each segment becomes invested with
another special membrane lying in close contact with the first and thus the cell
becomes the sporangium of a Chytridium (see section XLVI). About 60-80 hours
elapse between the entry of the spore and the emptying of the sporangium. The
process is the same if more than 1 spore has entered the tube of the Saprolegnia ;
when a single spore entered 2-14 sporangia were observed to be formed, 21
sporangia when 4 spores entered the tube. Rozella appears to form resting-spores
when many of its swarm-cells have made their way into the Saprolegnia. In this
case also the swarm-cells entirely disappear in the protoplasm of the host, which
then puts out stalked spherical branches resembling the oogonia of Saprolegnia, and
a resting-spore is formed from the protoplasm of each branch (Fig. 166, s). The
phenomena observed in Woronina are quite similar to those in Rozella apart from
certain differences in the form of the parts.

If no later investigations bring to light facts at variance with those here given,
and this according to Fischer’s statements is not probable -but cannot however be
considered to be impossible, the above case is an instance of a parasite surrendering
its individuality, so far as that can be recognised morphologically, after its entrance
into the host; it becomes changed into a part of its host, and the two can no longer
be distinguished from one another by our present means of investigation. The
parasite also communicates new properties to the host which is some two hundred
times its. size, and through them the host developes into its own parasite. This
transmutation of the host by the parasitic spore which has coalesced with it, though
peculiar, is yet analogous with the fertilising effect of the spermatozoid on the
oosphere of organisms which in the sexual sense are highly differentiated from one
another.

Fungi which form Lichens.

Section CXIV. A large number of species of parasitic Fungi employ Algae
as their hosts, either unicellular Algae which live isolated, or pluricellular Algae,
or Algae which unite together in gelatinous colonies. The germ-tube of the Fungus

} Ueber d. Parasiten d. Saprolegnieen. See also citations on page 171.

396 DIVISION IIL.—MODE OF LIFE OF THE FUNGI.

grows roung the cells of the Algae and developes into a thallus. The Alga follows
this growth, inclosed in a definite form between the hyphae of the Fungus, and thus
forms an integral part of the thallus. As the Alga grows, the chlorophyll in its
protoplasm is constantly engaged in assimilating carbon dioxide and forming organic
carbon compounds for the use of the Fungus. On the other hand the rhizoid-
branches of the Fungus (see page 45) spread in and on the substratum and
contribute the needful mineral food. The two processes of vegetation mutually
support and supplement each other. The Alga can live alone, as a plant containing
chlorophyll, though it may be open to question whether it can do so in all cases;
but its vegetation is not hindered by the Fungus, it can often be shown to be
permanently promoted by it. The Fungus as a strictly obligate parasite is
dependent for its vegetative growth on the Alga, without which it cannot attain
to its full development, and in most cases can scarcely get beyond the first stages of
germination.

The power of assimilating carbon dioxide which the Alga possesses in virtue
of its chlorophyll makes it unnecessary that organic carbon compounds should be
supplied as food to the thallus formed of itself and the Fungus in combination.
Very many of the forms in this group do in fact live on places like bare stone or
the ground, which do not supply these compounds. The question whether other
species, which live on the bark of trees, humus-soils and similar substances, do partly
vegetate as saprophytes has not been thoroughly examined ; but Frank’s observations
on species living upon the bark of trees, which will be further noticed below,
are in favour of the existence of a saprophytism of the kind.

In one point the Fungus is the superior in the common household; it alone
produces spores, the Alga with a few exceptions remaining barren as long as it is
combined with the Fungus '.

The bodies thus composed of Fungus and Alga combined are known by the
name of Lichens; it is equally well known that this name indicates an important
phenomenon in nature, and is applied to a very varied series of forms, large enough
to fill the pages of many descriptive works and local floras.

It follows necessarily from the above that two component parts, a Fungus
and an Alga, sometimes even several Algae, can be distinguished in every Lichen,

The general morphological characters of the Fungi which form Lichens have
been already stated in previous sections of this book. In the vegetative part they
consist of hyphae connected together in the various ways described in section I,
and in most cases united into a Fungus-body. According to the course of develop-
ment indicated by the sporiferous structure the great majority of Lichen-fungi belong
to the Ascomycetes, both Discomycetes and Pyrenomycetes, a few recently become
known to us to the Hymenomycetes.

The number of algal forms which enter into combination with Fungi is
according to our present knowledge not inconsiderable. There is one corresponding
Alga to each species of Lichen, in other words, each species of Lichen-fungus is
confined to a certain species of Alga. It is rare that two are found together in a
Lichen, and then one of them always predominates over the other. On the other

1 Synalissa symphorea Nyl. See Bornet in Ann. d. sc. nat. ser. 5, XVII, p. 50.

CHAPTER VII.—PHENOMENA OF VEGETATION.—LICHENS. 397

hand the same species of Alga may ‘serve as host to different species of Fungi, and
serve accordingly as a component part in very different forms of thallus.

The following list contains the genera and groups of Algae which are known
to form Lichens; the reader is at the same time referred to Schwendener’s and
Bornet’s special works and to some others also which will be named below, and to
the general works on the Algae’. Figures 167-169 represent some of these Algae
as they appear in the thallus of the Lichen and in most cases in connection with the
hyphae of the Fungus by which they have been attacked.

FIG. 167. Lichen-forming Algae. The Alga is in all cases indicated by the letter g, the assailing hyphae by 4, A Protococcus
viridis, Ag. (Cystococcus, Nag.) attacked by the germ-tube from a spore of Physcra parictina. B Scytonema from the thallus of
Stereocaulon ramulosum. C Nostoc from the thallus of Physma chi , Mass, D Ge from the thallus of
Synalissa Symphorea, Myl. E Protococcus sp. (Cystococcus) from the thallus of C/adonia Jurcata, P. ACDE magn. 950,
B 6so times. After Bornet.

1. Chlorophyll-green Algae.

(a) With short usually round cells living free or loosely united, but not forming
filaments or cell-surfaces, the group of ‘ Palmellaceae’: Protococcus, Kg., Pleuro-
coccus, Menegh., Cystococcus, Nag. (Figs. 167 A, Z, 168), Dactylococcus, Nag.,
Stichococcus, Nag.

(6) With cells firmly connected together into filaments and cell-surfaces, the
group of ‘Confervae’: possibly species of Ulothrix and especially the Chroolepus-
forms (Trentepohlia, Mart., Bornet) (Fig. 169) distinguished by the orange colour
of the contents (haematochrome) in addition to the chlorophyll. To these may
be added the genus Phyllactidium said by Bornet to be the Alga of Opegrapha

! See especially Nägeli, Gattungen einzelliger Algen ; also Kirchner, Algenflora von Schlesien.

398 DIVISION III.—MODE OF LIFE OF THE FUNGI.

filicina, and Cunningham’s! Mycoidea parasitica which with some other allied Algae
helps to form the species of Strigula common on evergreen leaves in the tropics.

-2, Algae which are blue-green, violet and other colours, owing to the
presence of phycochrome, and are often united together into large bodies by
means of their gelatinous membranes.

(2) Nostocaceae with their cells forming filaments: Calothrix, Ag. (Schizo-
siphon, Kg.), Seytonema, Ag. (Fig. 167, B), Lyngbya, Ag., Nostoc, Vauch.
(Fig. 167, C), Stigonema, Ag. (Sirosiphon, Kg.).

(5) Chroococcaceae with their cells not forming filaments: Gloeocapsa (Fig.
167, D), Chroococcus, Aphanocapsa, Nag.

FIG. 168. Cystococcus. a—e from the thallus of /#7-
bricariatiliacea. g from the thallus of Sphaerophoron
coralloides. f from the thallus of Usnea barbata. c,
d isolated algal cells, the rest with hyphae attached to
them. c—/ cells dividing. a—e and g magn. 390,
J 700 times. after Schwendener.

FIG. 169. Trentepohlia (Chroolepus umbrinum, Kg.).
a from the thallus of Zecanactis illecebrosa, Duf. 6 from
the thallus of Graphis scripta. Magn. 390 times,

Section CXV.. Origin of the Lichen-thallus. If the ripe ascospore of
the Lichen-fungus is placed on a moist substratum, it in most cases readily puts
out germ-tubes; these may in some cases form numerous branches (see page 113),
but they always perish after a certain time if they do not encounter suitable Algae,
even when the germination has taken place on a substance favourable to the nutrition
of the Lichen.

Supposing the substratum to be favourable and the right Alga to be within reach
(see Fig. 170), the germ-tube puts out branches on one side, which seize on the
Alga. If the Alga consists of single isolated cells, as for instance in the Pleurococcus-
lichens observed by Stahl, smaller branchlets are formed at the points of contact with
an algal cell, which closely embrace it and inclose it in fresh ramifications. If the
Alga is a compact pluricellular body, as in the Nostoc-lichens examined by Reess,
in which the cells united together in rows are surrounded by broad gelatinous
membranes and the protoplasmic bodies therefore are imbedded in a large quantity
of an intermediate gelatinous substance, the hyphal branches penetrate into the jelly
and put out branches in it which grow luxuriantly through the algal body and unite
with the protoplasmic bodies of the cells. At the same time in all cases known to

ca
} Trans. Linn. Soc. London, ser. 2, I, p. 301.

CHAPTER VII.—PHENOMENA OF VEGETATION.—LICHENS. 399

us the germ-tube from the spore puts out other branches, which penetrate into the
nutrient substratum and evidently obtain the necessary mineral matter from it. If
there is no substratum of this kind, as when the plants are grown on glass plates, the
above processes do not go beyond the very first stages.

The two observers just named carried the cultivation of their plants, with the
precautions suggested naturally by the circumstances stated above, from germination
to the production of the fully grown thallus, which in some cases also produced
sporocarps. The same results were obtained in a series of other cases by the
investigations of Bornet and Treub at least as regards the earliest stages, and these
investigations and a comparison of
fully developed thallus-forms show
distinctly that the first stages of
the development have a close re-
semblance to one another in all
or almost all Lichens, though ac-
companied with certain specific
modifications which were naturally
to be expected throughout. Even
the peculiarities observed by Frank
in the development of the thallus
of certain Graphideae, as Arthonia
vulgaris and Graphis scripta, which
grow on the bark of trees, are
really only specific modifications.
In this case the hyphae of the
thallus, which can only have come
from the germ-tubes of the spores,
though the observations on this
point are still imperfect, make their
way into the outer layers of the
periderm in smooth stems of oaks
and ashes and there grow as FiG. 170. Ea pound pluricellular pore of Exdocarpon pusti-

¢um, cultivated on a microscopic slide and putting out numerous germ-

saprophytes independently, that is tubes. T a bicellular compound spore of Thetidium minutulum also

ger ona micr pcells of Pleurococcus ejected with the
* tf spores from the h i of Endocarpon and v ing on the slide;
without Algae, into a thallus formed px a group of several cells of Pleurococcus formed at the spot by the

of an abundance of slender hyphae ersmihofsngt cls. a ses of Pewroocnsatacked and partly grown
which spread through the cells of eee es those which are vegetating in freedom. After Stahl. Magn.
the periderm. Then its proper

Alga, Chroolepus umbrinum (Fig. 169), finds its way from without through the
cell-walls of the peridermis into the previously formed hyphal thallus and is seized
by it. The cells of the Chroolepus are in rows forming filaments with apical
growth, and it is by means of this growth that they penetrate into the thallus, in
the same way as mycelial hyphae pierce through membranes. The Alga is a frequent
inhabitant of the bark of trees and makes its way into the periderm for its own
purposes. Its penetration into the thallus of the Fungus can scarcely be supposed
to be caused by the Fungus, but is merely an adaptation which favours the formation
of a Lichen.

400 DIVISION IIL—MODE OF LIFE OF THE FUNGI,

Lecanora pallida commences its growth according to Frank’s observations with
the development of a hyphal thallus in the periderm like the Graphideae just
mentioned, while the Alga which belongs to it, a form of Cystococcus (?) with free
round cells, comes ‘casually’ into contact with the hyphal thallus, its cells being
caught in the superficial crevices of the periderm in which it is spreading and there
seized upon by the Fungus. This is the origin no doubt of many Lichens which
occur in the same situation.

The nicest adaptation between Alga and Fungus, and one which goes so far as to
exclude ‘accident,’ is displayed in a small number of species of Lichens which Stahl
especially has closely examined: Stigmatomma cataleptum, Endocarpon pusillum,
Polyblastia rugulosa, etc. Here the cells of the Alga departing from their usual
behaviour make their way regularly into the hymenium of the sporocarps of the
Fungus, and increase to such an extent between the paraphyses, that they lie in great
quantities round the asci as they ripen. Whenever any spores are discharged a
certain number of algal cells adhere to them and are ejected with them from the
sporocarp, and are ready at once to be seized upon by the germ-tubes.

The morphological characters of the Alga when it is assailed by the Fungus
experience a more or less profound change from its condition in the free state. Size;
structure and arrangement of cells are affected in a manner which varies in the same
species of Alga according to the species of Fungus to which it serves as host. In
this point also specific differences which are noticed in descriptive works on the
Lichens make themselves apparent in different cases. We will only mention here as
an example of these differences the smooth round gelatinous colonies of Nostoc
lichenoides and similar Algae, which are changed by the intrusive Fungus into lobed
thallus-bodies with progressive growth in the direction of the margin, but usually without
the structure and arrangement of the algal cells which they contain being affected.
With these may be compared the hymenial Algae of Stahl just mentioned. These in
Endocarpon pusillum are a form of Pleurococcus. Within the hymenium the cells
of the Alga are very small, roundish in form and a pale green, and they multiply by
successive bipartitions, the new cells separating from one another. When seized by
the hyphae of Endocarpon their diameter increases to six times the original size, their
parietal chlorophyll-corpuscles assume a bright green colour, and the bipartitions
are continued with irregular arrangement of the successive partition-walls and a
corresponding change in the grouping of the cells themselves. The Alga retains
these characters as the thallus developes. If the same Pleurococcus-cells when ejected
from the hymenium of Endocarpon pusillum are seized upon by the hyphae of
Thelidium minutulum, they assume the same green colour, but they do not increase
so much in size, and within the surrounding hyphal weft the divisions take place by
partition-walls disposed alternately in three directions and cutting one another at
right angles. In accordance with these divisions the cells are arranged in rect-
angular packets with blunt angles and divided into squares, just as they are arranged
when vegetating free and alone (Fig. 170, 175).

Lastly it is of importance to call attention to a fact noticed by Frank in the
Lichens mentioned above as studied by him, that a part of the algal cells in the
Lichen may to a great extent or entirely lose their chlorophyll without apparently
dying in consequence of the loss; but this point requires closer investigation.

CHAPTER VII. —PHENOMENA OF VEGETATION,—LICHENS, 401

If the Alga is released from its union with the Fungus by natural or artificial
means, it may, as we learn from the researches of Famintzin and Baranetzki,
Schwendener, Bornet, Woronin, and Stahl, continue to vegetate, recovering its typical
morphological characters as an Alga, if the necessary conditions are present. See for
example Fig. 170.

Where the Alga is much altered in the Lichen, careful examination of liberated
cells is often necessary for the certain determination of the species. Such an examina-
tion has yet to be made in the case of many of the Lichen-algae, especially the Palmel-
laceae, and consequently these forms cannot at present be named with certainty and
exactness.

Section CXVI. Form and structure of the Lichen-thallus. The seizure
of the Alga by the Fungus is followed by the development of the combined body into
its ultimate form, its growth into the perfect Lichen-thallus (the blastema of Wallroth),
on which organs of reproduction of the Fungus make their appearance when the
highest development has been reached. These organs in the majority of Lichens are
sporocarps (apothecia and perithecia) together with spermogonia (see page 211); in a few,
which will be briefly noticed again at the close of this account, they are dastdza-
bearing hymenia; in many they are small drood-buds which separate spontaneously
from the thallus and are known as soredia. As a general rule the Alga takes part
only in the construction of the thallus and soredia and not in that of the sporocarps
and spermogonia or the basidia-bearing hymenium. The ‘thallodic’ margin of the apo-
thecia which is characteristic of many genera and contains Algae (see Figs. 86, 87, 89)
belongs, as the name rightly expresses, to the thallus and not to the apothecium. It
has often been observed indeed at the first beginning of the formation of the apothecia
(see page 213), that algal cells are included in the primordial hyphal weft; but they
die away in most species without increasing in size or number in the sporocarp itself.

Nylander? was the first who called attention to a remarkable exception to this
tule in the case of the pyrenocarpous species just mentioned, in which the Algae,
—Pleurococcus and Stichococcus in the best ascertained cases,—which are taken into
the primordial sporocarp, grow with it and multiply their cells to such an extent
that they gather thickly round the asci. This is the origin of the hymenia containing
Algae and the hymenial algal cells of Stigmatomma cataleptum, Sphaeromphale,
and especially Endocarpon pusillum and Polyblastia rugulosa which have been
especially investigated by Stahl, as was mentioned on page 400%, The algal cells are
distinguished by their considerably smaller size from their sister-cells in the thallus to
which they belong.

The fully developed thallus as regards its outward configuration appears in three
chief forms, which are not however sharply distinguished from one another: the
fruticose (thallus fruticulosus, filamentosus, thamnodes, Fig. 86 A), which rises with
a narrow base from its substratum, and is either simple or more usually branched like a
shrub ; the /olaceous (thallus foliaceus, frondosus, placodes, Fig 86 2), in form a flat,
leaf-like, usually lobed and crisped body which spreads over the surface of the sub-
stratum, but is only attached to it at one or at several scattered points and can

! Synopsis meth. Lichenum, p. 47.
? See Beitr. z. Entwicklungsg. d. Flechten, where the literature is cited.

[4] pd

402 DIVISION III.—MODE OF LIFE OF THE FUNGI,

therefore be separated from it without much injury; and the erus/aceous (thallus
crustaceus, lepodes), a flat crust on or in the substratum and adhering firmly to it
at least by its whole under surface, so that it cannot be separated from it without
injury. The genera Cladonia and Stereocaulon are peculiar, having shrub-like
formations (fodelia) rising from scaly or granular foliaceous bodies (the thallus or
protothallus of the Lichenologists). These forms all agree in two points of structure ;
they are composed, as has been said, of hyphae and of algal cells inserted between
them, and from the first commencement of their formation hyphal branches from the
base or surface turned towards the substratum enter the subtratum as rhzzoid-hyphae,
which sometimes, especially in foliaceous species, are united into rhizoid-strands.
These organs by which the plant attaches itself to the substratum and takes up food-
material are termed by Lichenologists
rhizines, and they often penetrate,
especially in species living on rock or
soil, as much as a centimetre deep into
the ‘substratum and spread through it in
dense ramifications. The rhizoids of
thesp ecies which live in the rind of trees
seem never to penetrate far into it, at
all events they do not reach the living
tissue of the rind. In many species,
which, like the Graphideae examined by
Frank and Lecanora pallida, form thin
crusts in the rind of trees, we find in
place of distinct rhizoid-branches the
system of hyphae described above, which
spreads in superficial periderm-layers
without going further inwards. These
hyphae may form a persistent thallus
which grows all its life entirely in the
FIG. 171. Usnea barbata. A optical longitudinal section of periderm along with the Algae which it

the extremity of a thin branch of the thallus which has become a ni 1
ae ren ta GollMlca of peice GaiFig: Sn. Beans eee has attacked, as in the above-mentioned

section through a stronger branch with the point of origin of an mi - .
adventitious branchsa; 7 cortical layer, # medullary layer, x stout and similar Graphideae and ın Pyr enula

ae ae" # apex ofthe branch. nitida, and it may be covered by one or

more layers of periderm-cells, in which

case it is termed by Lichenologists Aypophlocodic; or it makes its way out to the outer

surface of the periderm in consequence of the subsequent growth in thickness of
the parts which contain the Algae, and forms there an epiphlocodtc crust.

In other points of structure differences appear, which have no simple relation
to these growth-forms, but may be repeated in each of them. Lichenology since
Wallroth’s time has accordingly distinguished between the Aeferomerous and the
homotomerous thallus. The former is peculiar to the ‘true Lichens’ (Lichenes of
Fries, Lichenaceae of Nylander, Gnesiolichenes of Massalongo), the latter to the Phyco-
lichenes of Massalongo (Collemaceae of Nylander, Byssaceae of Fries). The hetero-
merous thallus occurs in the large majority of species, and displays in fact a structure
the main features of which can be clearly defined. The homoiomerous on the contrary

CHAPTER VII-—PHENOMENA OF VEGETATION.—LICHENS. 403

can at present only be described as not heteromerous, and under this head certain types
may be distinguished by positive characters, the most suitable of which are drawn
from the Algae which form part of each species, as will be explained below.

1. The growth of the Fungus-body in the heteromerous thallus (Fig. 171)
is progressive in the direction of the apex in the fruticose Lichens, in the direction of
the margin in the others (see section XII). The apex or margin which takes the
lead in growth is formed of the terminal portions of the hyphal system, and these are
the form-elements which determine the course of the development. The Alga
follows in its growth the apex or margin which precedes it, moving after it, but always
continuing at a certain distance behind it. This growth by gradual advance may be
followed in successive transverse zones by intercalary surface-growth and growth in

ee
oA NOR

eee

F1G.172. Physcia partetina, Kbr. Section FIG. 173. Sticta_fuligzs T section the
through the young thallus; o upper rind-layer, foliaceous thallus ; the letters as: in Fig. 172, also m medullary layer, r
% under rind-layer, g algal zone (Cystococcus). rhizoid strands. The algal zone here consists of a species of Chroo-
After Schwendener. Magn. 500 times, coccus with thick col b and bluish green

protoplasm which is black in the figure. After Sachs, Magn. soo times.

thickness, caused by the formation and insertion of new hyphal branches and algal
cells and also by the increase in volume of those previously formed.

The ramifications also in the foliaceous and fructicose thallus proceed from the
hyphal system. They are partly bifurcations, and partly arise ‘adventitiously’ at
points not in most cases very exactly and morphologically defined.

The structure also of the mature heteromerous thallus (Figs. 171-173)

is in its ground-plan that of the Fungus-body of the Lichen. We may as a

rule distinguish in it a comparatively thin (its average thickness is about 10 p)

usually transparent dense peripheral rind-layer (stratum corticale) clothing the

free surface and a weft beneath the rind which is usually loose and everywhere

furnished with interstices containing air, the medulla or medullary layer (stratum
pd2

404 DIVISION III-—MODE OF LIFE OF THE FUNGI.

medullare). Both layers belong to the hyphal system, their constituents are ramifi-
cations of the same hyphae. The cells of the Alga are in almost all cases inserted
where the medulla and the rind meet. Together they form a green zone of varying size
projecting into the medullary tissue to a different depth at different points, everywhere
traversed by single hyphae of the medulla running to the rind, and in some places
showing larger interruptions. This is the algal layer or algal zone which is commonly
termed the third tissue-layer. But single algal cells or groups of cells are often found
scattered through the medulla, as in Solorina and Placodium, or the whole mass of
algal cells is distributed with tolerable uniformity through the medulla, as in Bryopogon.
Sundry modifications of this type and small deviations from it occur in different
species and groups of species. The following are the most important ones :—

Some fruticose thalli, especially if cylindrical in form, are covered all round with
a uniform rind, as in Usnea (Fig. 171),
Bryopogon, Roccella, Sphaerophoron
and others. In many fruticose forms
with a flat thallus (species of Evernia
and Cetraria) and in most foliaceous
forms the rind of the upper surface
which is towards the light is different
from that of the lower surface (Figs.
172, 173); in Anaptychia, Peltigera,
Solorina and most of the foliaceous
portions of the thallus in the Cladonieae
the upper side only has the rind up to
the margin, the lower surface has no
rind.

When there is this difference in the
two surfaces, the algal zone apart from
the scattered cells only appears on the

side towards the light. Even in the
atc, Lele nt, Kiron ie mat Tas 4 almost cylindrical thallus of Sphaero-
vertical longitudinal section through the same. 7 black marginal phoron with a uniform rindall round it, it
bands, g groups of Algae, 2p A slighty Circum- =
ference of B magn. 45 times, but the whole completed from greater is often more strongly developed onthe
re side towards the light than on the lower
; one. The podetia of Cladonia, which
according to Krabbe! are to be regarded as strongly developed parts (envelope-appara-
tus) of apothecia but which always have the structure and growth of a fruticose thallus,
are always without a rind when young, and in some species, as C. rangiferina, never
have a rind, their surface being formed of a loose hyphal weft containing Algae. Most
species are at a later period of their life partially covered with small wart-like rind-scales,
and some are completely covered with a rind, as C. furcata.

Some of the crustaceous forms, for example the genera Psora, Psoroma, Placodium,
Endopyrenium &c. and Thalloidima candidum are only distinguished from the folia-
ceous by having their under surface covered all over with rhizoid-hairs which penetrate
into the substratum. These hairs either spring as branches from the elements of a
distinct rind, as in species of Placodium and Endopyrenium, or where the rind
is wanting on the under surface they are direct continuations of the medullary hyphae.

Other crustaceous Lichens, those namely with areolate surfaces or which have a
granular appearance, have essentially the same structure in the fully developed areolae
as the species mentioned above which are without a rind on the under surface. Some of

1 See on page 222.

CHAPTER VII.—PHENOMENA OF VEGETATION.—LICHENS, 405

them which have a very thick thallus, as Haematomına ventosum, Mass, and Lecanora
Villarsii, are distinguished by a very thick medullary layer, sometimes forming according
to Tulasne 38 of the whole thickness of the thallus. The granulation or areolation
is produced by the course of growth which has already been described. This is the
case at least in a number of species examined by Frank and myself which live in
bark, Lecidella enteroleuca, Kbr. (Lecidea parasema, Nyl.), Ochrolechia pallescens,
Lecanora pallida and Pertusaria, and it is probable that a large number of other species
of similar habit agree with them in this respect.

In these Lichens (Fig. 174) the margin of the thallus consists simply of several layers
of hyphae, which radiate in the direction of the surface (A) and run parallel to one
another in a vertical and radial longitudinal section (3). These together form a broad
marginal zone often of different thickness in different radial strips, and with the extremi-
ties of single free hyphae projecting beyond its circumference. The peripheral portion of
this zone, as Frank has pointed out, always grows through outer layers of the periderm,
and first emerges from them at some distance from the periphery where it is thicker.
The margin advances by marginal progressive growth and the surface of the thallus
therefore enlarges. The algal cells which grow and multiply move forwards in the
same direction behind the margin, and wzthiz the layers of hyphae. They lie collected
together into groups, and as the algal cells constantly increase in number the hyphae
are continually forming fresh branches in and around each group, and becoming more
and more densely interwoven till their originally radial course is at length obliterated ;
this happens especially on the side towards the substratum. Thus a coil of closely
interlacing hyphae inclosing the algal cells is formed at the points indicated, the
extremities of the filaments nearest the surface running chiefly at right angles to the
surface and forming a rind which is usually very thin (Fig. 174 B).

The spots in which these formations take place rise above the surface of the marginal
zone in the form of arched projections, small warts, which increase rapidly in number
and size with the increase of the distance from the margin till they touch one another
and become confluent. The mature thallus appears variously uneven, warted, granular
or areolated according to the shape of the projections, their elevation and the extent to
which they become confluent. In some forms with a very thick thallus, as Haematomma
ventosum, Mass. and Lecanora Villarsii, Ach., the areolation of the surface of the thallus’
may be caused according to Schwendener by the rind becoming fissured in consequence
of excessive dilatation of the medulla; this may of course happen independently of the
first formation of the areolae as here explained.

Some crustaceous Lichens, as Lecidea (Rhizocarpon, Kbr.) geographica, L. confer-
voides and Urceolaria cinerea according to Tulasne’s figures, show an edging round
their distinctly areolated thallus, formed of radiating branched confervoid strands of
hyphae firmly united together and adhering closely to the substratum. The areolae of
the thallus are formed in centrifugal succession on this marginal expansion, at first
as small scales or warts which gradually increase in size till they are in contact with
each other on every side. We need not assume that there are other differences between
this mode of development and that first described, besides the one difference that in the
present case the marginal zone is divided into the separate strands, while in the other
it is coherent. The structure of the areolae shows no special peculiarities. The
marginal strands of the last-mentioned forms as well as the marginal zone of those
which grow in the manner of Lecidella enteroleuca, Kbr., are often under the name
of hydothallus confounded with rhizoids or root-hairs. The term protothallus as it
indicates a commencing state is more suitable but is at the same time unnecessary.

As regards the minuter structure of Lichens, the hyphae of most of the heteromerous
‘species are comparatively slender. The hyphae of the medulla are usually slenderer
than those of the rind, and their cells may be very long, as in Usnea, sometimes
reaching according to Schwendener a length of 200 4; but the hyphae may also
be short-celled, as in Fig. 172, and their structure may even be pseudo-parenchymatous

406 DIVISION III.—MODE OF LIFE OF THE FUNGI,

as in Endopyrenium and Catopyrenium. Details on these points will be found in
descriptive works and especially in Schwendener’s earlier writings. It has been already
observed that the medulla is in most cases furnished with broad interstices containing
air; in some fruticose forms, as Cladonia and Thamnolia, there is a broad axile cavity
occupying the largest part of the total volume of the thallus. In Usnea a dense axile
hyphal strand passes through the middle of the thallus and is surrounded by a loose
weft of hyphal branches running to the rind (Fig. 171) ; in Evernia vulpina and E. flavi-
cans the loose medulla is traversed by several similar longitudinal strands which
approach and separate alternately in an irregular manner.

The hyphal branches which compose the rind are united together without inter-
stices in all cases except in some species of Roccella. They are either unmistakeable
hyphal filaments, with the lumina of their segments at least evidently elongate-
cylindrical, though they may not be as long as the cells of the medulla; or they are
composed of short isodiametric rounded prismatic cells, so that the rind often has
a very regular and delicate pseudo-parenchymatous structure, as in Parmelia, Physcia
(Fig. 172), Endocarpon, Sticta (Fig. 173) and Peltigera. It is only in Bryopogon
and Anaptychia ciliaris that the course of the much elongated hyphae of the rind
is almost strictly longitudinal even in the mature thallus. In all other cases the hyphae
lie in every direction and form an irregularly woven weft or pseudo-parenchyma ; or
they are nearly exactly vertical to the surface, as in the pseudo-parenchymatous cell-
rows of Endocarpon and Peltigera and in a very beautiful form in tufted branches of
Roccella, in which also the lateral connection is somewhat loose and the extremities
are free. The single branched hyphae may be clearly distinguished in thin sections
especially of Roccella fuciformis, and a slight pressure will isolate them.

The thickness of the membranes, the breadth of the lumina in the medulla and rind,
and the mutual relations of the two layers vary extremely in the different genera and
species ; the details will be found in Schwendener. The cell-walls are often unusually
thick especially in rind-hyphae with long segments (Usnea, Bryopogon, Sphaerophoron
&c.), and from their close connection with one another they seem to form a homogeneous
mass, in which the lumina appear as narrow canals. But this homogeneous mass is

„ seen in thin sections, especially when treated with dilute solution of potash or ammonia,
to consist of separate obscurely stratified membranes. The structure of these rind-layers
has much resemblance to that of some sclerotia (see page 31).

The differences between the rind of the upper and under side lie in the thickness of
the rind-layer, the size and arrangement of the cells, the colour and similar points (see
for example Figs. 172, 173).

The surface of the rind is sometimes covered with a fine _se/t of hairs which are small
projecting hyphal branches, as on the upper side of Anaptychia ciliaris, Peltigera
malacca, P. canina also in the young state, and on the lower side of Sticta and Nephroma.

Among the wart-like prominences which occur on the upper surface of some foli-
aceous and fruticose species, those of Peltigera aphthosa and the smaller ones of Usnea
are thickenings or exuberant growths in the rind; the larger ones in Usnea and the
warts and scales of Evernia furfuracea in the matured state are a kind of projections of
the thallus, consisting of algal cells inclosed by an air-containing tissue connected with
the medulla and invested by the rind. The blackish branched enlargements on
the upper side of Sticta fuliginosa and Umbilicaria pustulata are formed of a dense
hyphal weft containing Algae surrounded by a single layer of pseudo-parenchymatous
rind with a brown membrane. A similar structure has been observed in the wart-like
and rod-like excrescences, which often form a thick covering on the surface of many
crustaceous Lichens and cause the coralline appearance of the forms known by the name
of Isidium ; they require further investigation.

Peculiar interruptions of the rind occur on the under side of the thallus of Sticta.
They are either largish flat spots with a somewhat indistinct outline, as in Sticta pulmo-
nacea, or small circumscribed pits, the bottom of which is formed by the expgsed

CHAPTER VII.—PHENOMENA OF VEGETATION.—LICHENS. 407

medulla and the margin surrounded bya raised portion of the rind. The pits are formed
according to Schwendener by the cortical layer being first thrust outwards in the form of
a wart by exuberant growth of the medulla and then ceasing to grow in the pro-
tuberant part, while the surface of the thallus continues to enlarge all round it. In
some species, as Sticta macrophylla, the interruption in the rind is preceded by the forma-
tion of a hollow space in the enlargement in the medulla. The pits are termed
cybhellae ; the older view, that they are small gemmae-cups, receptacles of soredia, is
unfounded, or is true only in the case of certain species, as Sticta aurata (Schwen-
dener).

There is little to add to what has been already said of the crustaceous Lichens.
Most of them are distinguished by the comparative thickness of their rind.

The margin of many species, especially those which live in the bark of trees, is
often marked by a black line which has been noticed by many writers ; Lecidea entero-
leuca, Kbr. among the species specially mentioned above is an instance of this phenome-
non, which is evidently caused by the dark colouring of the cell-membranes of the few
uppermost layers of hyphae ; this colouring appears at a certain period in the life of
the plant in the marginal zone where there are still no Algae. Where the thallus is
engaged in active growth, the black line, if it is present, runs within the young colourless
margin. The black colour is absent from the prominences which contain algal cells,
doubtless because the few cell-layers which are so coloured are forced apart by the
dilatation of the prominence and soon thrust aside. When the thalli of many individuals
of the species in question come in contact with one another, the black lines often seem
to form persistent boundaries between the different individuals like the lines on a geo-
graphical map. The reason of this may be, that the marginal growth of the thallus
ceases where it encounters others, and the colour then appears in the marginal zone and
there remains (see Fig. 174). :

The thallus of some foliaceous Lichens, Umbilicaria pustulata for instance and of
many crustaceous forms, is capable, as we learn from Schwendener, of a growth in thick-
ness which lasts a long time, often for years, and with this is connected a decay and
death of the rind which advances from without inwards. The dead layer often remains
lying on the living one as an almost structureless transparent mass ; in other cases it is
quickly destroyed by atmospheric agencies and becomes indistinguishable. The loss
is replaced by regeneration from the inner surface, so that the rind always remains of
about the same thickness. The medullary hyphae whose course is in the algal zone
ramify and intertwine and form a tissue without interstices, which becomes like the rind
and lies close against it on the inside. The outer algal cells are inclosed in this secondary
rind-weft, but they gradually shrivel up and die while new ones are formed inside by
division. If the process has been going on for some time, the whole of the rind is studded
with dying or dead algal cells. They may be shown by the cellulose-colouring of their
membranes with iodine, especially if first treated with potash.

The heteromerous thallus exhibits some remarkable peculiarities in respect of the
material constitution of the hyphae. The membranes, as far as they have been exam-
ined, show the characters of the lichenin mentioned on page 10. They are transparent,
almost always colourless in the medulla and in the inner portions of the rind, brittle when
dry, swelling considerably and becoming soft and flexible in cold water. Some of the
cells of the rind at least contain air when the plant is in the dry state, and the whole
layer is thus rendered opaque. Absorption of water expels the air and increases the
transparency of the membranes, so that the green algal zone is seen through it ; hence
the change of colour in the surface caused by moistening the plant. The interstices in
the medulla continue to contain air even when moistened, and the tissue therefore
remains opaque. The membranes of most hyphae are not coloured by iodine ; they
dissolve on addition of sulphuric acid either without assuming any colour, as in
Usnea barbata, or after first turning brown, as in Anaptychia ciliaris according to
Speerschneider, or after acquiring a violet hue which is sometimes very intense. The

408 DIVISION IIL—MODE OF LIFE OF THE FUNGI.

membranes of the rind of Cetraria islandica, except those of the superficial coloured cells,
turn a beautiful blue with solution of iodine alone, as Schleiden' has observed,
owing to the presence of Dragendorff’s Lichen-starch in the cells (see page 10).
The membranes of the medulla of Sphaerophoron coralloides show the same colour
with iodine; Schwendener found that the rind of Cornicularia tristis and of some other
species not precisely determined became blue with iodine only here and there.

The membranes of the rind, especially the superficial layers, in many Lichens are of
different hues owing to the presence of a colouring matter uniformly diffused through
the substance of the rind, as in Cetraria islandica, Bryopogon jubatus and many others ;
the dark colour of the under rind of Evernia furfuracea comes from the colouring of the
outer lamellae of the membranes ; the narrow lumina are seen in section surrounded
by thick colourless membranes, between which are dark brown bands forming boundary
lines; the matters imparting this ‘uniform colouring have not yet been thoroughly
investigated, at least not microchemically.

Asecond series of colourings is caused by granular imbeddings or incrustations. The
tissue of very many Lichens is seen to contain small round or elongated granules of some
organic substance lying partly on the free surface and on the medullary hyphae, partly
imbedded in the membranes which are united together without interstices. Granules of
this kind, which are either colourless or only of a faint yellow colour even in the mass,
occur for instance in the upper rind of Placodium cartilagineum and other species, in
Imbricaria caperata, Dill., I. incurva, P. and other species, on the medullary hyphae of
Peltigera, Solorina saccata and some species of Sticta (Schwendener), on the rind of
Roccella, especially R.fuciformis and of Thamnolia and in the inner rind of Sphaerophoron
coralloides ; distinctly or intensely yellow granules are found outside the rind of Evernia
vulpina and Physcia parietina, ot imbedded in the peripheral region of the rind of
Cetraria straminea (Schw.) and Usnea barbata and in the whole of the membranes of the
rind of Psoroma gypsaceum, or scattered in groups through the rind of Bryopogon diver-
gens (Ach.) and B. sarmentosus and especially of B. ochroleucus where they form an
uninterrupted layer near the surface, and in the medullary hyphae of Sticta aurata
and S. crocata and some other species ; red incrustations are found on the medullary
hyphae of Solorina crocea. The presence of these bodies in the substance of the thallus
and on it causes either a lively coloration, or, as in Thamnolia and Roccella, a dull yellow
aspect and opaqueness in the parts in which they are found. They are all readily
soluble in alkali either without change or with loss of colour, or at least deliquesce and
become turbid under the influence of these agents, as in Physcia parietina and Solorina
crocea, in the latter also without change of colour. It was not improbable therefore
that the granules consisted of chinic acid, and Fr. Schwarz has recently proved that
this is the case in a number of species.

Another series of infiltrations and imbeddings is composed of inorganic matter.
First and foremost is the rust-colour not unfrequently assumed by individuals (‘formae
oxydatae’) of many crustaceous Licliens which are typically of another colour ; it has
often been stated and has now been proved by Giimbel, that this colour is due to the
infiltration of a salt of iron, perhaps of a vegetable acid. Still more remarkable
is the occurrence of calcium oxalate in many Lichens especially of the crustaceous
division, either in the form of octahedral crystals, or of irregular crystalline bodies, or of
small granules. In accordance with the rule which prevails in the rest of the Fungi it
is never found inside the cells, but either on the surface of the rind, or on the medullary
hyphae or in the interstices between them, or imbedded in the shape of minute granules
in the membranes of the compact tissue of the rind. The latter is the case for instance
in Psoroma lentigerum, in which the entire rind is wholly opaque and white in reflected
light, owing to the close array of granules of the salt. Besides the above species, in
which the medullary hyphae are also incrusted with granules, they occur also in Ochro-

' Grundzüge, II.

CHAPTER VII.—PHENOMENA OF VEGETATION.—LICHENS. 409

lechia tartarea, Mass., in Urceolaria scruposa which has an enormous number of crystals
occasionally of large size in the interstices of the medulla, and in Thalloidima candidum
where granules are found both on and in the upper side of the rind ; the thallus of the
Pertusarieae, especially Pertusaria fallax, contains large, irregular, interstitial crystalline
masses ; granular incrustations are found in the medulla of Chlorangium Jussuffii, and
smaller isolated crystals are scattered about in the interior of the thallus of Megalospora
sanguinea and M. affinis, Mass., Ochrolechia pallescens, Mass. and other species.

Yet it would be incorrect to say that calcium oxalate occurs in all Lichens, or always
in the octahedral form. It does not even occur in all crustaceous forms; I have as yet
looked in vain for it in Lecanora pallida and in Lecidella enteroleuca, Kbr. Neither
Schwendener nor myself have found it in any foliaceous species except Placodium and
Endocarpon monstrosum mentioned by Schwendener, and we both noted its absence
in most fruticose forms. In the young branches only of Roccella fuciformis I have seen
tolerably large crystals which were not however chemically examined, and groups of
small rods and granules composed of the salt in question in the rind and medulla of
Thamnolia vermicularis.

This is not the place for a full enumeration and description of the substances organic
and inorganic which analysis has detected in Lichens ; the facts have been collected
and the literature noticed by Rochleder! and by Husemann and Hilger”. It isremarkable
that the ash-constituent of Lichens is often very large, but on this point also information
must be sought in special treatises®.

The Algae of the heteromerous thallus in the majority of species are chlorophyll-
green ‘Palmellaceae’; Cystococcus is the Alga in most of the Parmelieae; Pleuro-
coccus has been determined by Stahl in Endocarpon pusillum and Thelidium minutulum,
and{Stichococcus in Polyblastia rugulosa ; Bornet has determined the Alga in Solorina
saccata and possibly also in S. crocea, Nephroma arcticum and Psoroma sphinctrinum,
Nyl. to be Daetylococcus, Nag., and in Sticta glomulifera, Ach. he conjectures it to
be an Ulothrix. It will be seen that a considerable variety of species are known to
occur in Lichens, and it is desirable that the Algae should be isolated and more exactly
determined in other forms which have only been hastily examined. Roccella has a
species of Chroolepus for its Alga. The Nostocaceae and Chroococcaceae which owe
their blue-green colour to the presence of phycochrome are peculiar to many hetero-
merous Lichens; species of Nostoc according to Bornet’s more or less certain
determinations occur in Nephromium, Nyl., Peltigera, Stictina, NyL, and in the species
of Sticta which have blue-green Algae, the remaining species being formed with Algae
from the group of the Palmellaceae (Fig. 173) ; Seytonema is the Alga of Coccocarpia
molybdaea, Pers., and blue-green Algae of undetermined species are the Algae
of the Lichen-genera Psoroma and Verrucaria.

The thallus of some heteromerous Lichens is peculiar in including a second Alga
in addition to the species which is its principal and constant constituent. The chief Algae
in Solorina saccata and S. crocea, some species of Stereocaulon, Sticta glomulifera
and some others‘ are Palmellaceae ; but Nostoe occurs with them in the Solorinae

} See Gmelin’s Handb. d. Chemie, VIII.
2 Die Pflanzenstoffe.
3 Thomson in Ann. d. Chem. u. Pharm. 53, p. 254.
Knop in Erdm. Journ. f. pract. Chem. 38, p. 46; 40, p. 386; and in Ann. d. Chem. u,
49, Pp. 108.
Giimbel, Ueber Lecanora ventosa (Denkschr. d. Wiener Acad. Math. Naturw. Cl., XI).
Lindsay, Popular Hist. of Brit. Lich. p. 51.
Uloth in Flora 1861, p. 568.
Th. Fries, Genera heterolichenum, pp. 8-12.
* Forssel has recently published an elaborate account of these occurrences. See Studier öfver
Cephalodierna, in Abhandl. d. Schwed. Acad., Anhang. 8, Nr. 3, Stockh, 1883, and in Flora, 1884.

410 DIVISION III—-MODE OF LIFE OF THE FUNGI,

and in Sticta, and Seytonema or Stigonema in Stereocaulon. In many forms, for
example in Sticta and Stereocaulon, the Nostocaceae are localised in peculiarly shaped
branched or convex outgrowths from the thallus, which have received the name
of cephalodia. ;

The Alga is firmly attached to the adjoining hyphae; where the structure is a dense
pseudo-parenchyma as in Endocarpon it is squeezed in between the hyphae ; where it
is filamentous and lacunose the hyphae send out branches, which attach themselves
firmly to the algal cells ; it not unfrequently happens that the hypha comes into contact
with the new cells formed by division of the algal cells, and in that case it sends out
small branches from the point of contact which embrace the Alga closely in the way

A

FIG. 175. Thelidii ‘9 di A perithecium on the thallus; 2 groups of Algae, FiG. 176. vw—d Cystocoleus ebe-
m the part of the thallus without Algae spreading in the 2 the peritheci neus, Thw. a extremity of a branch
cut through the middle, represented diagrammatically and slightly magnified. 3 a group seen from without. 5 a similar one
of Algae with hyphae growing round them, magn. 480 times. After Stahl. in optical longitudinal section ; x the

Algae; a and 4 from preparations
made transparent by Schulze's solu-
tion. ¢, @ transverse sections,

e, / Coenogonium Linkit, Ehrb.;
e slender branch of the thallus with a
ateral branch in optical longitudinal
section. transverse section through
a stronger branch. After Schwen-
dener. a, 4, ¢, d,¢ magn. 390, / 300
times.

described above in the case of germ-tubes (Fig. 167 EZ). The Stigonema which is
peculiar to the cephalodia of Stereocaulon furcatum is seized by the hyphae in the
same way as in Ephebe which will be noticed further on.

2. There are a considerable number of Lichens, which are reckoned in
descriptive works among the heteromerous species and agree with them on the whole
in the manner of their growth, but which depart from the scheme of the heteromerous
thallus in having no differentiation of a rind, and having the Algae scattered among
the hyphae. Of this kind are the marine fruticose Lichinae which have Calothrix
scopulorum, Ag. for their Alga’, the frondose Pannarieae with Algae from the groups
of Nostoc and Scytonema, a large number of Graphideae of different genera,

! See Kny in Sitzgsber. d. Naturf. Freunde 1874, and Bornet in Ann. d. Sc. Nat. ser. 5, XVII.

CHAPTER VII.—PHENOMENA OF VEGETATION.—LICHENS. 411

Graphis (Opegrapha) varia, O. plocina, Kbr., O. saxatilis, Schaer. and many other
species, together with Lecanactis illecebrosa, Kbr., species of Arthonia, and Pyrenula
nitida, in which the crustaceous thallus with progressive marginal growth consists of
an air-containing weft of slender hyphae, which grow round filaments of Chroolepus
as their Alga without any differentiation into medulla and rind (see above on p. 399).
For further details in these cases which require more exact investigation the reader is
referred to special treatises.

3. Another special form of structure must now be mentioned, the granular
green thallus of certain Lichens living on the ground which Stahl has examined
carefully in Thelidium (Fig. 175). In this case the thallus is formed of a loosely
woven mass of hyphae which vegetate beneath the surface of the ground. Branches
of these hyphae rise to the surface and attach themselves as in germination to the
proper algal cells there present; the particular Alga of Thelidium is Pleuro-
coccus. The hyphal branches grow completely round the cells forming a thin layer,
and so follow the growth of the Alga that this relation between the two elements is
constantly maintained, the hyphae pushing in between the products of the division of
the algal cells as they are formed one after another, and twining round them as at the
first. In this way groups of Algae are formed lying on the hyphal thallus and
surrounded and held fast by the hyphae. No further differentiation takes place in
them. It is possible that the process is the same in Biatora vernalis and similar forms,
which should be examined on this point.

4. The thallus in Chiodecton nigrocinetum, Mont., Byssocaulon niveum,
Mont. and Coenogonium Linkii (Fig. 176 e, f) consists of a branched filamentous
Alga, belonging according to Bornet to the genus Trentepohlia and probably the
same as Kiitzing’s Chroolepus flavum, and surrounded by a dense weft of fungal
hyphae; Coenogonium confervoides, Nyl. consists of a larger species nearly
approaching according to Bornet to Chroolepus villosum and wrapped in a similar
fungal weft. In these forms of thallus the Alga either does not alter its growth at all,
or very little. In Coenogonium the Lichen has the conferva-form and the Alga advances
by longitudinal growth, so that the tips of its branches are often found free from the
hyphae. A similar structure is seen in the European species Racodium rupestre, Fr.
(Cystocoleus of Thwaites) which is known only in the sterile state, with the difference
however that here the hyphae which acquire thick and brown membranes surround
the apex also of the branches of the Chroolepus in a single layer which has no inter-
stices (Fig. 176, a-d). We learn from Bornet that Opegrapha filicina, Mont. behaves
in the same way as Coenogonium, only that there the Alga is one of the species
of Phyllactidium which form scutiform cell-layers on the leaves of tropical Ferns.

5. The Collemaceae or gelatinous Lichens are a group in which the
Algae are Nostocaceae or Chroococcaceae with gelatinous membranes or membrane-
sheaths; the Fungus makes its way into the gelatinous membrane, and, with the
exception of the rhizoids and the sporocarps which issue from it, grows entirely in-
side it and ramifies in it. Fungus and Alga are differently related to one another in
the common growth in the different species, but the Fungus never dominates the Alga
so decidedly as in the heteromerous forms. The form and structure of the Alga is
accordingly different in different cases, but the structure always varies less than the form.

412 DIVISION I1I.—MODE OF LIFE OF THE FUNGI,

Ephebella Hegetschweileri' in the fresh condition has quite the look of a
Scytonema (Fig 167, B, g); but if the plant is heated in solution of potash the
gelatinous sheath of the Scytonema-filaments is seen to be traversed by a compact
weft of very delicate hyphae running chiefly in a longitudinal direction, out of which
apothecia are sometimes, but rarely, developed.

The thallus of Ephebe (Fig. 177, 178), Spilonema, Gonionema, Nyl. and
Lichenosphaeria, Bornet has the structure and the branched shrubby form of

J

Fic. 177. Ephibe pubescens, Fr. A FIG. 178. Ephebe pubescens, Fr. A branched filiform thallus
branched filiform thallus of Stigonema with of Stigonema with hyphae of the Fungus growing through its
the hyphae of the Fungus growing through gelatinous membranes. « tip of the thallus after being boiled in
its gelati b E ity of a solution of potash. 4, ctr i igh the upp
branch of the thallus with a young lateral portion ofa branch, 4 tratisverse section through the lower and
branch a; % hyphae, g cells of the Alga, gs older portion of a branch. The cells of the Alga are indicated by
the apex ofthe thallus AfterSachs. Magn. the dotted shading. Magn. 390 times.

500 times.

Stigonema, Ag. (Sirosiphon, Kg.) with the addition of the hyphae which pass in the
longitudinal direction through the outer wall of the Stigonema-filament and grow in
length behind its advancing apex; but their branches are seen in older transverse
sections of the Alga to intrude in numbers between its cells. Single branches of the
Alga which is attacked by the Fungus may continue quite free from it.

The genus Collema and its nearest allies Synechoblastus, Leptogium, Mallotium,
Obryzum, Plectopsora (Arnoldia), Lempholemma (Physma) and some others are

1 Itzigsohn in Hedwigia, I, 123.

CHAPTER VII—-PHENOMENA OF VEGETATION.—-LICHENS. 413

Nostoc-colonies attacked by the Lichen-forming Ascomycete. The hyphae of the
Fungus intrude between the cell-rows of the Alga, which are strung together like the
beads of a rosary interrupted by heterocysts and imbedded in a firm jelly; they
branch in a manner which varies according to the species, and determine the general
growth of the compound thallus. °

In most forms numerous peripheral branches of the hyphae run vertically into
the surface of the gelatinous colony and end blindly in it. Leptogium, Obryzum and
Mallotium (Fig. 179) are exceptions to this, in which the extremities of the peripheral
branches pass into a rind or outer membrane, a simple or in places a double layer of
polyhedric tubular cells without interstices with pellucid contents and colourless or
brown walls, which covers the whole thallus. The membrane of the cells is often
stronger on the upper side of the thallus and thickened more on the outer than on the
inner side, recalling the epidermis of the higher plants. Numerous multicellular hairs
spring from all parts of
the cells of the lower
rind in Mallotium, some- fg
times short and isolated,
sometimes longer and
united in bundles; they
serve to fix the thallus
to the substratum.

No direct and in-
timate connection can be
perceived in most species
between the branches of

the hyphaeand the single ric. 179. Madlotivm Hildebrandit, Garov. a radial longitudinal section through the
algal cells. But the spe- the rit ham typhee and NonorAummme magn to Open 08
cies of Plectopsora and

Physma are distinguished by the presence of haustoria, short hyphal branches which
grow in the direction of any Nostoc-cells and either lay their conical extremity close
upon them (Arnoldia minutula, Born.), or penetrate into them (species of Physma).
The cells thus attacked become at first larger and fuller of protoplasm than those
which are untouched; but according to Bornet they die prematurely (see Fig. 167 C).

Of these Nostoc-Lichens which have no rind the Gloeocapsa-lichens or Ompha-
larieae (Omphalaria, Synalissa, Thyrea, Paulia, Fée, Peccania, Mass., Enchylium
and Phylliscum, Nyl.) are really distinguished only by the Algae, which belong
to the genus Gloeocapsa and its allies. Their cells are round and multiply by
division in three directions, and after division they separate from one another inside
the broad gelatinous membranes, which are stratified as a result of their mode of
formation and hold the cells together in one mass.

Of the branches of the hyphae some only thrust themselves into the gelatinous
membranes, some attach themselves by their blunt extremity directly to the individual
cells, so that most of the cells are borne on them as on a slender stalk. Each
division of the algal cell is followed by a branching of the stalk, which thus supplies
the new stalk that is wanted (Fig. 167 D, 180). Hence the cymose grouping of the
stalked algal cells, which is a very striking feature in some species, and which

414 DIVISION III.—MODE OF LIFE OF THE FUNGI.

Thwaites was the first to describe’. Neither changes of structure nor premature
death have been observed in the algal cells on account of this attachment to the
hyphae. But the effect of the Fungus on the Algae is shown in a very remarkable
manner by the formation of a thallus of a fixed shape, which in some species is of
comparatively large size and has a progressive marginal growth, while the gelatinous
colonies of Gloeocapsa which are not attacked by the Fungus have a very indefinite
shape and are only loosely connected together.

6. We conclude this account of the Lichens with a special consideration of those
which are formed with Hymenomycetous Fungi, a mode of proceeding which
is notindeed consistent with the arrangement hitherto adopted but which will be found
to conduce to perspicuity. The few species of the kind that are known belong to the
tropical zone and are distributed among the genera Cora, Fr., Rhipidonema, Matti-
rolo, Dictyonema, Mont., and Laudatea, Johow. They grow on dead parts of plants
and are attached to them by a copious growth of rhizoids or mycelium. Cora Pavonia,

FIG. 180. a,5 Thyrea pulvinata, Mass. @ vertical longitudinal section through the margin of the thallus, 4 groups
of Algae. c Synalissa sp. (Plectopsora botryosa, Jack, Leiner and Stitzenberger, Krypt. Bad. Nr. 301), portion of a thin

transverse section through a small lobe of the thallus. The surface of the gel which is violet-red in nature
is shaded in the figure. Circumference of a magn. go times, the other parts di icall p! d, 6 magn. 390,
c 720 times.

Fr. developes its thallus in the form of a flat semicircular fan resembling Stereum or
Thelephora (see p. 53) with marginal progressive growth. The thallus consists of
a loose air-containing weft of stout hyphae without evident differentiation into
medullary tissue and rind; its middle layer contains an abundance of groups of
Chroococcus-cells closely surrounded and embraced by branches of the hyphae.

The thallus of Dictyonema and Rhipidonema, of similar construction to that of
Cora, is constructed out of filaments of Scytonema, which are attacked by the hyphae
of the Fungus, as in Ephebe and Ephebella, but by greater numbers of them, and
are thus taken up into a thallus-tissue formed of hyphae only. Johow’s Laudatea
spreads over the substratum like a crustaceous Lichen, being attached to it by a
close mycelial weft, and winds its hyphae round Scytonema-filaments on the free
surface in the manner of Ephebe.

Hymenomycetous sporiferous layers (see page 300) with numerous paraphyses
and comparatively few four-spored basidia are formed on the under side of Cora and
Dictyonema and on the free surface of Laudatea ; in Cora in the form of broadly

1 Ann, and Mag. of Nat. Hist. ser. 2, vol. III (1849).

CHAPTER VIl.—PHENOMENA OF VEGETATION.—LICHENS. 415

conical bodies like small flat apothecia of Peziza with the apex of the cone towards
the thallus and produced by suitable branching of a tuft of hyphae; these bodies
when they are present in large numbers unite together at the margins and form
patches of some size; in Dictyonema and Laudatea they are smooth expanded
layers usually resembling those of the Thelephoreae. The sporiferous structure of
Rhipidonema is not clearly understood. Further details will be found in Mattirolo
and Johow.

Section CXVII. The thallus of very many Lichens forms small brood-
buds which separate spontaneously from the thallus and under favourable conditions
may develope into a Lichen-thallus similar to the parent structure. These have been
known since Acharius’ time by the name of soredia. They appear to be wanting in
some species, as in Lecidea geographica and Endocarpon pusillum ; in others they
are very abundant, as in many species of Usnea, Bryopogon, Ramalina, Evernia,
Imbricaria, Parmelia, Pertusaria and others.

In their most general characters the soredia are small portions of the thallus
which have a distinct form in each case and consist of one or more algal cells and the
hyphae which have grown round them. As the soredium developes into a new
thallus the two constituents behave
in the manner which has been
described above in the special
types of thallus. Their structure
at the moment of separation is
in many cases that of the mother-
thallus in a rudimentary form,
as in Collema where they are
roundish branchlets, prolifications
of the upper surface or margin of
the thallus appearing like granules to the naked eye, in the Graphideae also which
contain Chroolepus, in Roccella and others. Detailed investigations in many
species have not yet been made.

The soredia have been carefully studied by Tulasne and especially by
Schwendener in the typical heteromerous forms which contain Palmellaceae, especially
Cystococcus, and there their development and structure usually exhibit the following
peculiar features (Fig. 181).

They are formed at spots in the algal zone beneath the rind which are distributed
over the surface or margin of the thallus and vary according to the species. Branches
of the hyphae twine round an adjacent algal cell or group of cells which have arisen by
division and form a soredium ; if a group of cells is thus attacked the hyphae also
insinuate themselves between the cells and twine round each of them. The roundish
body thus formed consists entirely of one or more algal cells and an envelope of
hyphae which differs in compactness and colour in different species, and in some, as
in Bryopogon, is not perfectly closed; how it is separated from the thallus has not
been clearly ascertained.

By unlimited repetition of this process at one spot the soredia accumulate there
beneath the rind, which swells up and at length bursts, the soredia emerging from

FIG. 181. Usnea barbata. c. an isolated mature soredium, with an algal cell
(Cystococcus) in the envelope of hyphae. @ another with several algal cells
in optical longitudinal section. ¢, /two soredia in the act of germinating ; the
hyphal envelope has grownout below into rhizoid-branches, and above shows
already the structure of the apex of the thallus (see Fig. 171). After
Schwendener. Magn. more than 500 times,

416 DIVISION III-—MODE OF LIFE OF THE FUNGI.

the fissure as a powdery mass loosely held together by the hyphae of the thallus,
which are drawn out with it. These powdery and easily dissipated accumulations of
the separate bodies which have now been described are termed by Schwendener
soredia-heaps or sort, and it will be well to retain his terminology, though the word
soredium was originally applied to the whole heap.

A soredium can give rise to an unlimited number of new soredia in the manner
just described after a sorus has emerged from the rind, and even after the soredia
have separated from one another and been dispersed as dust. This uniform
multiplication leads to the formation of layers and accumulations of soredia which are
not unfrequent in shaded spots, as in the case of Physcia parietina. Where the
conditions are favourable to vegetation a thallus is formed and fully developed from
them (see Fig, 181, ¢, 7). Such a thallus may even be frequently produced in Usnea
according to Schwendener on the parent-thallus, forming soredial branches which
remain firmly united to it.

Excessive development of roundish soredia-heaps with a remote resemblance to
apothecia on a crustaceous or foliaceous thallus, on which apothecia are not at the
same time produced, gives rise to the forms on which Acharius has founded his
pseudo-genus Variolaria.

Pseudo-lichens. The above account necessarily excludes from the class of Lichens
those forms which are ranked with them in our books because they have been collected
by Lichenologists, but which do not possess the one mark of the true Lichen, namely, the
presence of Algae in their thallus. Among these are the Celidieae, Abrothallus and
others, which are parasitic on the thallus of Lichens, the genus Myriangium mentioned
above on page 107, the Arthopyrenieae examined by Frank 1, Körber’s Naetrocymbe,
and Atichia®. All these forms except the last are simple Ascomycetes ; Atichia, according
to Millardet’s able investigations, is a Fungus of uncertain position which forms clustered
spore-groups. Those species also will of course be excluded which have been placed in
the same genus with others having the true Lichen-thallus, and are really nearly related
to them but have not the mode of life of a Lichen. Frank found that Arthonia vulgaris
has the Lichen-thallus (see on page 399), but Arthonia epipasta, Kbr. has only hyphae
inits thallus. Both species live onthe bark of trees ; the former is a Lichen-fungus with
that habitat, the latter simply a saprophytic Fungus. There is nothing strange in this,
for there are natural genera in other parts of the system, in which some of the species
are usually parasitic, while others are adapted to a saprophytic mode of life, for example
Sclerotinia. Norman’s Morioleae (Moriola, Spheconisca) also appear to me, from the
descriptions which I have read of them}, to be to say the least doubtful Lichens ; they
deserve further investigation. If they really have Algae in their thallus, they are
simply Lichens which have also the power of inclosing parts of Liverworts, pollen-grains
and probably other strange bodies in their thallus.

Historical notice of the Lichens. It is well known that the views of botanists
respecting the thallus of the Lichens up to the year 1868 were not those which have been
given in the preceding pages. It was supposed to be a body whose constituent parts all
proceeded from one another, and ultimately from the germinating spore ; the algal cells
especially, so far as any clear conception had been formed about them, were regarded as

1 Biol. Verhaltn. einiger Krustenflechten in Cohn’s Beitr. z. Biol. II.

2 See Millardet, as cited on page 262.

® See Botaniska Notiser, 1876, No. 6a. Also Just’s Jahresber. 1875, p. 105. I have not been
able to consult the paper Allelotismus in K. norske Vid. Selsk. Skrifto. VII, 1872.

CHAPTER VII.—PHENOMENA OF VEGETATION.—LICHENS. 417

products of development of the hyphae, That conversely the hyphae also might proceed
from the Algae, was a view which was at any rate often expressed, but which could not be
Maintained by those who looked fully into the facts on which it was supposed to rest.
Wallroth expressed this view most decidedly, though he could not in his day draw from
it the histological conclusions which have been stated above, when he named the algal
cells gonidia, brood-cells, and expressly understood by this name asexual organs of re-
production produced from the thallus and capable of developing under favourable
conditions into a new and perfect Lichen-thallus'. This view of Wallroth was in fact
derived from the correct observation of the origin of the thallus from soredia, and from
confounding small soredia of heteromerous species with the Algae of their thallus, and
even with other free green algal cells, a mistake quite conceivable in his day. But after
this confusion and the non-reproductive character of Wallroth’s gonidia had long been
recognised, the expression was still retained in an altered sense for the Algae of the
Lichen-thallus, and with it the terms gonddial layer or gonimic layer (stratum gonimon),
hymenial gonidia, and others of the same kind. The term chromidia proposed by
Stitzenberger? met with little favour. I have avoided the word gonidia in the foregoing
account, because it is a convenient expression in its original acceptation for the repro-
ductive organs of the Fungi, and has been so used with all possible consistency in my
former chapters, and to apply it in a different sense to the thallus of the Lichen-fungi
would necessarily have caused confusion. At the same time it is unnecessary to intro-
duce a new term, because the old word Alga declares the real nature of the objects
briefly and distinctly, and satisfies all the requirements of the terminology.

After the discovery of the fact that the Algae of the thallus are not reproductive
organs but assist in the vegetation of the plant by means of their chlorophyll, a long
time elapsed before clear insight was obtained into their true character. They con-
tinued to be regarded as parts of a simple organism, the Lichen, and this view was
confirmed by the observations first of Bayrhoffer and after him especially of Schwen-
dener, which showed that they are often so placed at the extremities of branches of the.
hyphae in heteromerous species containing Cystococcus that they may very well be,
supposed to be the swollen terminal cells of the hyphal branches forming chlorophyll.
I myself adopted this view in the case of the heteromerous Lichens in my first edition
in 1865. In the case’of other species, especially the gelatinous Lichens containing
Chroococcaceae and Nostocaceae, there appeared to me to be objections to it which could
not be removed, and I was led to propose the following alternative: either the Lichens
in question are the perfectly developed and fruitful states of plants, the imperfectly
developed forms of which have hitherto been placed with the Algae under the names of
Nostocaceae and Chroococcaceae, or the Nostocaceae and Chroococcaceae are typical
Algae which assume the form of the Collemeae, Ephebeae, &c., when they are invaded
by certain parasitic Ascomycetes which spread their mycelium in the growing thallus
and often attach themselves to the algal cells containing phycochrome (Plectopsora,
Omphalarieae). Then Schwendener not only adopted the latter alternative at the close
of his work on the Lichen-thallus in 1868, but extended it to all Lichens and thus
founded the view which has been set forth in the preceding paragraphs.

The arguments which he advanced in support of this doctrine on the subject of the
Lichens are drawn from the purely anatomical data given above. They may be briefly
stated in the following manner: All Lichen-gonidia, as they have been hitherto termed,
are so like certain Algae that every one of them can be directly placed under some well-
known genus or even species of Algae; the ‘gonidia’ have never been distinctly proved
to have been formed from branches of the hyphae, but all observations tend to show
that the Alga has been attacked by a Lichen-fungus. Schwendener did not go beyond
this point even in his later and more elaborate work on the subject. Bornet’s investi-

} Wallroth, Naturgeschichte d. Flechten, I (1825), especially at p. 46.
? Flora, 1860, p. 216.

[4] Ee

418 DIVISION III.—MODE OF LIFE OF THE FUNGI.

gations which followed quickly on those of Schwendener were so extremely clear that
they were calculated to raise the probability of the view and the conviction of its truth
to the highest point, especially as Famintzin, Baranetzki and Woronin had previously
isolated Cystococcus and Nostocaceae from Parmelieae, Cladonieae and Peltigera
and cultivated them further as Algae with independent power of vegetation,—a mode
of proceeding which was carried out by Bornet in some other species. Cystococcus was
reproduced in abundance in these experiments from swarm-spores.

Still Schwendener’s view continued to encounter a strong opposition. It is not so
easy to shake off the yoke of the traditions in which men have been brought up. The
same early instruction which led me to a guarded expression of my hypothesis of the
Collemaceae and made Schwendener at first regard it as rash, had so fixed the convic-
tions of many who had devoted themselves specially to lichenology, that they rejected
sometimes with indignation a view which ‘pitilessly robbed their favourite Lichens
of their independent existence and turned them by the stroke of a magician’s wand into
a spider-like tyrant Fungus and a captured and enslaved Alga.” These words of Crombie
briefly indicate the point of view of the ‘lichenologists,’ and a paper by the same writer,
translated by von Krempelhuber in Flora, 1875, gives a condensed account of the
line of argument pursued by the opposition, and to this paper the reader is referred.

The arguments advanced scarcely touched the heart of the question. Appeal was
made to earlier statements respecting the origination of hyphae from ‘ gonidia’ and
gonidia from hyphae, which could not however stand the test of critical examination.
Körber! himself, the most acute in the search for effective arguments, admits the decisive
facts. He says that the hypha produced by the germination of the spore must meet
with the ‘gonidia ’ specifically belonging to it, that is, coming from the particular Lichen-
species, if it is to give rise to a normal Lichen. But this hypha and whatever else there is
in the Lichen-thallus except the ‘gonidia’ do not belong toa Fungus, buttothe Lichen, and
the ‘gonidia’ which are specifically necessary are no Algae, but free independent Lichen-
gonidia which have become ‘asynthetic.’ It is therefore a simple case of change of
name. That this is not the case as regards the Fungus-portion of the Lichen need not
be restated here. The view that the lower Algae which vegetate where Lichens are
found are Lichen-gonidia escaped from the thallus originated with Wallroth and was
often expressed after him?. It was excusable in the year 1825; but our knowledge of
the lower Algae had reached a point in 1874 which no longer permitted this summary
mode of dealing with them. With the needful limitations they must be admitted as
Algae in the sense which accords with our present views. The principal limitation is,
that the gonidium is an Alga which enters into the Lichen-thallus and may in some cases
leave it again, and this position has never been shaken.

The orthodox lichenologists had always one objection in reserve. They had the right
to require and could not help requiring that it should be shown how a Lichen-thallus
proceeds from the germ-tube of the spore and from the supposed Alga. Without
complete proof that this takes place Schwendener’s view was only a hypothesis, and
the more surprising the hypothesis was the more reasonable was it to say, that perhaps
there were things still unknown to us at the bottom of the whole matter, the discovery of
which might settle the question in another and unexpected manner.

Schwendener’s observation of the entrance of the hyphae of an unknown Fungus into
the jelly of algal colonies, which appear as constituents of Collemaceae, could not be
accepted as decisive, because it is not only possible but certain that this may happen
with several Fungi which are not Lichen-Fungi. Bornet’s observations and his and
Treub’s experiments in cultivation made some advance towards the decision of the
question, but their results were still imperfect. It was not till it was understood that the

} Zur Abwehr d. Schwendener-Bornet’schen Flechtentheorie, Berlin, 1874.
* See E. Fries, Lichenogr. Europ. XX.—Kiitzing in Linnaea, 1833;—Id., Phycol. generalis, p. 167.
—Hicks in Quarterly Journ. Micr. Sc. VIII, p. 239, and new series, I, p. 157.

CHAPTER VII.—PHENOMENA OF VEGETATION.—LICHENS. 419

young plant grown from the spore must meet at the same time with the Alga and with
suitable nutriment of other kinds that the experiments became decisive. Reess produced
Collema from its component parts with the thallus fully formed, but time was not allowed
for the development of the sporocarp. Then Stahl by judicious selection of the
objects to be experimented on effected the synthesis of three species of Lichens; he
gave a complete demonstration of the entrance of the Alga into the composite Lichen,
the changes which it undergoes there and its possible ultimate liberation, and he suc-
ceeded especially in proving that the same Pleurococcus may appear as a constituent of
more than one species of Lichen.

These results satisfied all demands and the Lichen-question was settled once for all
against the old traditional view.

The discovery by Mattirolo that the thallus of Lichens may also be composed
of Hymenomycetous Fungi was a welcome confirmation and illustration of the new
view.

There have in fact never been any real difficulties in the way of accepting
Schwendener’s theory ; the only obstacle to be encountered was the tradition which
had been cherished for some centuries. It must be allowed that it is perhaps difficult
to realise, how when Lichens are growing socially in large numbers each one of them
is formed by synthesis of spore and free Alga. But in most cases it is not necessary
to suppose that this is the case ; the primary synthesis may take place only seldom; the
large number of soredia produced will account for the most copious propagation of
the species which can be imagined. On the other hand Stahl’s observations on the
hymenial Algae show that there are adaptations which almost ensure the synthesis
every time that spores germinate. Considering the great variety of forms in the Lichens
it is possible that many special adaptations may yet be discovered in the course of
time. Frank’s work cited above supplies evidence in support of this view. It is more-
over quite conceivable that there are species of Algae which have become so adapted
to lichenism, that they can no longer attain their full development outside the Lichen-
combination, perhaps not even vegetate independently any longer?; examples of the kind
are not at present known, but the possibility of their occurrence should be borne
in mind.

Our historical sketch would not be complete without a record of the fact that since
the year 1878? Dr. Arthur Minks has attempted to rescue the old tradition by the dis-
covery of a new organ termed a microgonidium which takes part in the formation of a
Lichen-thallus of quite different structure from anything described above. More than
this short notice cannot be expected from the author of a serious botanical work,

LITERATURE OF THE LICHEN-THALLUS.

‘Geschichte und Litteratur der Lichenologie von den ältesten Zeiten bis zum Schlusse
des Jahres 1870,’ by A. von Krempelhuber, a veryremarkable work, gives in three volumes
containing altogether more than 1650 large octavo pages an account of the subject
indicated by the title-page, and a very careful notice of all the works connected with it.
The Regensburg ‘Flora’ is a rich repertory of Lichenology since 1855. The reader is
referred once for all to these two publications for all literary and historical details.

It is unnecessary to say anything more in this place about the various publications on
the sporocarps of Lichens and matters connected with them; a sufficient account has
already been given of them in Chapters III and V. It remains only to name the
authorities from which our account of the Lichens has been derived, so far as they have

1 See Frank, in Cohn's Beitr. z. Biol. d. Pfl. II.
2 Flora, 1878, p. 209. Also A. Minks, das Microgonidium, ein Beitr. z. Kenntn. d. wahren
Natur d. Flechten, 8°. Basel, 1879. See also Just’s Jahresber. 1876 and succeeding years,
Ee2

420 DIVISION III.—MODE OF LIFE OF THE FUNGI,

not been already mentioned in the text. Further information with regard to the litera-

ture of the subject will be found in the works here cited.

G. F. W. MEYER, Entw., Metamorphose u. Fortpfl. d. Flechten, Göttingen, 1825.

E. FRIES, Lichenographia Europaea reformata, Lundae, 1831. Introduction.

WALLROTH, Naturgeschichte d. Flechten, Frankfurt, 1825-1827.

KÖRBER, De gonidiis Lichenum (Diss. inaug. Berol. 1839) ;—Id., Ueber d. individuelle
Fortpflanzung d. Flechten (Flora, 1841, Nos. 1, 2).

BAYRHOFFER, Einiges ü. d. Lichenen u. deren Befruchtung, Bern, 1851.

L. R. TULASNE, Mem. p. servir & l’hist. organogr. et physiol. d. Lichens (Ann. d. sc. nat.
ser. 3, XVII), with 16 plates.

SPEERSCHNEIDER, Anatomie u. Entw. d. Hagenia ciliaris (Bot. Ztg. 1853, p. 705, 1854,
-P. 593) ;—Id., Anat. u. Entw. d. Usnea barbata dasypoga (Bot. Ztg. 1854, p. 193) ;—
Id., Anat. u. Entw. d. Parmelia Acetabulum (Bot. Ztg. 1854, p. 481) ;—Id., Anat.
u. Enews d. Ramalina calicaris (Bot. Ztg. 1855, p. 345) ;—Id., Anat. u. Entw. d.
Peltigera scutata (Bot. Ztg. 1857, p. 521).

NYLANDER, Syn. meth. Lichenum, I, Paris, 1858-60.

- Tu. M. FRIEs, Genera heterolichenum recognita, Upsala, 1861.

S. SCHWENDENER, Ueber d. Bau u. d. Wachsthum d. Flechtenthallus (Vierteljahs-
schrift d. naturf. Ges. Zürich, 1860) ;—Id., Unters. ii. d. Flechtenthallus in Nägeli,
Beitr. z.. wiss. Bot. Heft. 2, 3 u. 4, Teipaig; 1860-68 ;—Id., Ueber Ephebe (Flora,
1863) ;—Id., Die Algentypen d. Flechtengonidien, Basel, 1869 ;—Id., Erörterungen
z. Gonidienfrage (Flora, 1872);—Id., Die Flechten als Parasiten d. Algen (Verh. d.
Baseler naturf. Ges.), 1873. See also Bot. Ztg. 1868, p. 289, and 1870, p. 59.

S. BORNET, Recherches sur les gonidies d. Lichens (Ann. d. sc. nat. ser. 5, XVII,
tt. 6-16, and XIX, No. 5).

BARANETZKI, Beitr. z. Kenntn. &c. d. Flechtengonidien (Melanges Biol. Acad. Peters-
bourg, VI, Dec. 1867, and Pringsheim’s Jahrb. VII, 1868).

FAMINTZIN U. BARANETZKI, Zur Entwicklungsgeschichte d. Gonidien u. Zoosporenbil-
dung d. Flechten &c. (Bot. Ztg. 1867, p. 189, and Mém. Acad. Petersbourg, ser.
7, XI; also Bot. Ztg. 1868).

M. WORONIN, Sur les gonidies du Parmelia pulverulenta (Ann. d. sc. nat. ser. 5, XVI,
317).

M. Reess, Ueber d. Entstehung d. Flechte Collema glaucescens (Monatsber. d. Berlin.
Acad. Oct. 1871) ;—Id., Ueber d. Natur. d. Flechten (Samml. wiss. Vorträge von
Virchow u. v. Holtzendorff; Heft 320, 1879).

A. Borzı, Intorno agli officii d. Gonidii d. Licheni (Nuov. Giorn. Bot. Ital. VII, 1875).

M. TREUB, Lichenencultur (Bot. Ztg. 1873) ;—Id., Onderzoekingen over de Natuur der
Lichenen (Diss. Leiden, 1873), with an accurate account of the history of the subject
in addition to the author’s investigations.

A. Biol. Verhältn. einiger Krustenflechten in Cohn’s Beitr. z. Biol. d.
PA. II.

E. STAHL, Beitr. z. Entwickelungsgesch. d. Flechten, II, Leipzig, 1877.

O. aes Contribuzione allo studio del genere Cora (N. Giorn, Bot. Ital. XIII,
1881), . .

F. JoHow, Ueber westind. Hymenolichenen (Sitzgsber. d. Berlin. Acad. 21 Feb. 1884).

Secoxnp Part.

MYCETOZOA.

CHar. VIII. MORPHOLOGY AND COURSE OF DEVELOPMENT.

Tue name Mycetozoa is here applied to a group of Fungus-like organisms
amounting at the present time to nearly three hundred species, the larger number of
which are contained in the division Myxomycetes or Slime-Fungi (the Myxogasteres
of Fries) together with the smaller one distinguished by Van Tieghem under the name
of Acrasieae.

The resemblance of the Mycetozoa to the Fungi is due partly to their mode of
life and nutrition, partly to the close agreement in structure and biological characters
between their organs of reproduction and the spores of Fungi. A spore-terminology
corresponding to that of the Fungi will therefore be applied to the present group.
With this word of preliminary direction we now proceed to a more particular
examination of the group.

MYXOMYCETES.

Section CXVIII. The ripe spore of the Myxomycetes is round and ellipsoidal
with the structure of a simple Fungus-spore (see Figs. 182, 183, 193). Anepisporium
colourless or coloured, smooth or marked by characteristic surface-sculpture and
varying in thickness in each species, incloses a dense and homogeneous turbid
protoplasm, which contains one, or sometimes in abnormally large specimens, two
nuclei in the shape of round transparent bodies with a small central less transparent
nucleolus. Other bodies of definite shape are sometimes but rarely inclosed in the
protoplasm ; these have not been very closely examined, but are usually spoken of as
oil-drops or lumps of mucilage.

The spores are capable of germination as soon as they are ripe in most of the
species in which this point has been examined; the moment of maturity will be
described more exactly in section 120. It is only in the Cribrarieae and Tubulinae
that all attempts to procure the germination of the spores have hitherto been

422 SECOND PART.—MYCETOZOA.

without success. Germination takes place under conditions which will be more
particularly related in a subsequent page; in most species when the spores are
placed in water.

The germinating spore (Fig. 182) swells first of all by absorption of water, and
one or two small vacuoles, which disappear and reappear alternately, are seen near the
upper surface of the protoplasm in which rotating movements are often observed ; at
length, and usually 12-24 hours after the scattering of the spores, the membrane
bursts and the protoplasm oozes or creeps slowly out of the opening. The
protoplasmic body then either at once, as is the rule, or after a transitory period of“
rest, during which it assumes a spherical form, commences amoeboid movements,
undulating changes of outline and protrusions and withdrawals of pointed processes,
and in this way becomes elongated into a body which moves about in the water like
a swarm-spore and is known by the name of swarm-cell (Fig. 182 d-f).

The swarm-cell has the same structure as the protoplasmic body before it
emerged from the spore, only that the granules in the protoplasm are collected together
in the larger part of the cell, which is the
hinder part in the movement, while the anterior
part is free from granules and also contains
the nucleus. From one to three vacuoles lie
in the posterior part, one of which at least
is known as the contractile vesicle, because
in about a minute’s time it grows smaller and
disappears, and then reappears and enlarges
till it is one third or one half the breadth
of the protoplasmic body. The granules or
lumps of mucilage in the spore either continue
in the swarm-cell, or they are dissolved before

the protoplasm leaves the spore, or they are
weaning eazia Spores in water. (a before extruded and left behind within the membrane.

ruptured spore-membrane. e an older swarm.cell with

cia. fan amoeboid swarm-cell without cilia, The ine Ihe Swarm-cell has no firm membrane, but
193 bare omitted inthe drawing. Magna ame “careful observation shows that it is surrounded

by a tolerably broad, pellucid and indistinctly
defined envelope of the consistence of mucilage.

The movements of the swarm-cells are of two kinds: a Aoppimg and an
amoeboid creeping movement.

In the hopping movement the cell floats freely about the water with its anterior
extremity usually turned upwards. This extremity is finely pointed, the point being
drawn out into a long cilium or flagellum with an undulating and swinging movement;
in exceptional cases only there are two cilia. The posterior extremity is usually broad
and rounded off, and the presence of a cilium there is quite abnormal. The body
thus constituted rotates round its longitudinal axis in the circumference of a cone the
apex of which is formed by the posterior extremity. The cilium swings with an
undulating motion from side to side, making the swarm-cell move in a similar manner
and advance in one direction; sometimes there is no rotation, The body at the
same time exhibits constantly varying undulatory movements of its surface, with bending
and contraction and recurrent expansion of the parts.

CH.VIII.— MORPHOLOGY AND COURSE OF DEVELOPMENT.-—MYXOMYCETES. 423

In the creeping movement the swarm-cell lies on the firm substratum, and
either advances in one direction with a vermicular movement and. with the cilium
stretched out in front; or it assumes a roundish form and thrusts out processes,
pseudopodia, in every direction and then draws them in again. The two kinds of
movement, the hopping and the creeping, often pass into one another, and may
frequently be observed alternating with one another in the same individual with
apparently alternating retraction and protrusion of the cilium. Swarm-cells with
purely amoeboid motion have been unnecessarily distinguished by the name of
myxamoebae.

The swarm-cells multiply by bipartition, which, to judge by the vast numbers
sometimes obtained from a sowing of the spores, may be repeated through several
generations. The movement becomes more sluggish before division, the swarm-cell
contracts into a spherical form and the cilium and the vacuoles disappear. This is
followed by the appearance of an annular constriction in the middle which speedily
becomes deeper and in a few
minutes divides the body into two
spherical halves which at once re-
sume the characters of motile swarm-
cells. The nucleus becomes indis-
tinct during the division but does
not entirely disappear, and it may
be presumed from analogy that it
also is divided. Exceptions to the
rule here laid down have been ob-
served in Chondrioderma difforme
and Didymium praecox, in which
the protoplasm was divided inside
the spore-membrane and issued FIG. 183. Chondrioderma difforme. ı ripe spore. 2 the same ger-

ae minating. 3—5 swarm-cells. 6, 7 the same in the amoeboid state. 8 two
from it in the shape of two swarm- amoeboid swarm-cells in close contact. 9 the same when coalesced to

. form the beginning of a plasmodium. 10 three swarm-cells in contact with
cells, about as often as it escaped one another, 11 two of them after coalescence, the third still free. ı2

from it in the form described above. Aner Cenkowski fom Sachs Lehrbuch Mage asstimes cn
Famintzin and Woronin too found

that the protoplasmic body which came out of the spore in the Ceratieae divided
by successive bipartitions into eight portions, which separated from one another
as swarm-cells provided with cilia.

Section CXIX. The further development of the swarm-cells consists in their
uniting together to form the large motile protoplasmic bodies, which Cienkowski
named plasmodia. The course of events in this process was directly and completely
observed under the microscope by Cienkowski in Didymium leucopus, Fr.,
Chondrioderma difforme (Didymium Libertianum) and Perichaena liceoides, Rost.
(Licea pannorum, Cienk.). A number of less perfect observations of Lycogala,
Fuligo and Stemonitis which have been communicated to me, and the resemblance to
one another of all fully formed plasmodia, justify the assumption that the course of
development is essentially alike in all Myxomycetes.

The phenomena directly observed in the development of plasmodia are of the
following kind (Fig. 183). In a few days after the spores are sown the divisions

00

7 6

424 SECOND PART.—MFCETOZOA.

become less frequent, most of the swarm-cells have the creeping form in which they are
without cilia, and many have increased in size and contain single large strongly
refringent granules. Then they approach close to one another in groups com-
pösed of two or more and again separate, till at length two or three are seen to come
into close contact with one another and become fused together into a single body,
the young plasmodium. This body exercises an attraction in a way not yet
explained upon other swarm-cells of the same species, and they attach themselves one
by one to its surface and coalesce with it. The newly formed plasmodium is
distinguished by its greater size from the swarm cells without cilia, while it exhibits
essentially the same movements and changes of shape.

The plasmodia when once formed by the coalescence of the swarm-cells begin
to increase in size, and as they grow assume the form usually of branched strands,
their dimensions far exceeding those of the swarm-cells (Fig. 183, 12, and Fig. 185).
The latter is especially the case in some of the Physareae (Calcareae of Rostafinski) ;
the stouter branches may in these species even exceed the thickness of a strong bristle,
and the plasmodium in the form of a copiously branched reticulated or frill-like
expansion covers surfaces varying in extent from an inch to a foot. This is the case
in Fuligo varians (Aethalium septicum of authors), Leocarpus vernicosus, Didymium
Serpula and D. praecox and Diachea elegans. Other species of Physareae as
Chondrioderma difforme and Didymium leucopus, Fr. have usually much smaller
plasmodia, just large enough to be clearly seen with the naked eye or invisible to it,
and this is the case with all the other forms which have been hitherto examined not
belonging to the Physareae.

The plasmodia of the Physareae if sufficiently supplied with water spread over
the surface of the substratum, usually decaying parts of plants, in the form of veins and
net-works of Veins which have been well known since Micheli’s time and especially from
Fries’ excellent descriptions, and from their mesentery-like appearance have been termed
Mesentericae. As they spread also readily on the microscopic slide, their structure
and conformation have been specially investigated (Figs. 184, 185). ‘They are chiefly
composed of a soft protoplasm of the consistence of cream, which may be readily
spread out into a shapeless smear and is usually colourless but sometimes yellow, as
in Fuligo, Leocarpus vernicosus, and Didymium Serpula, or a reddish yellow as in
Physarum psittacinum. The microscope enables us to distinguish in them a colour-
less homogeneous slightly turbid fundamental hyaloplasm which usually appears
distinct as a bounding layer of varying breadth, and a granular protoplasm which
forms the chief mass of the plasmodium. Vacuoles are formed not unfrequently in
the granular plasm and sometimes also in the hyaloplasm, some of which alternately
disappear and reappear while others are more stable. The granules are more or less
numerous in different species and individuals, but are always present in sufficient
quantities to make the great mass of the plasmodium highly turbid, and in the stouter
branches of some species (Fuligo) quite opaque. The composition of the granules
is in some cases not precisely determinable; in others they consist of calcium
carbonate. These granules of lime form the larger part of the granular mass in the
‘Physareae, where they are spherical with dark contours, glistening, and of tolerably
uniform size. Where the yellow colouring matter occurs it generally accompanies
the granules of lime, partly appearing as a thin coating on the single granules, partly

CH.VIII.—MORPHOLOGY AND COURSE OF DEVELOPMENT.—MYXOMPCETES. 425

forming somewhat large roundish bodies with a delicate outline in which one or
more lime granules are imbedded; it is soluble in alcohol at least in Fuligo and
Didymium Serpula.

Nuclei were not at first observed in the plasmodia. Cienkowski even stated
expressly that the nuclei present in the swarm-cells disappear when they coalesce.
But Schmitz" and Strasburger? have recently established the presence of numerous
nuclei in the plasmodium, and it may be presumed that they are the persistent nuclei
ofthe swarm-cells and products of their division.

Besides the proper constituents of the plasmodium strange bodies of very various
kinds are often found inside it, such as spores of Fungi and Myxomycetes (see Fig. 183,
12), parts of plants, &c. These objects are taken up from without into the interior
of the growing and moving plasmodium, one may say engulfed by it, in a way
which will be noticed again below, and they may be provisionally termed the sold
ingesta,

FIG. 184. Chondrtoderma difforme. Ex- FIG. 185. Didymium leucopus. Portion of the margin of a small reticulated
ities of b ofa pli dii Magn. pl di “After Ci i from Sachs’ Lehrbuch. Magn. 100 times.
390 times,

Reinke has recently published an elaborate investigation of the various substances
which enter into the composition of the plasmodium of Fuligo*, to which the reader
is here referred.

The amoeboid movements of the swarm-cells are continued in the plasmodia.
They may be seen in larger specimens by continuous observation even with the naked

1 Sitzgsber. d. Niederrhein. Ges. 4 Aug. 1879.
2 Zellbildung u. Zelltheilung, 3 Aufl. p. 79.

3-Studien ii. d.-Protoplasma von J. Reinke u. H. Rodewald in Untersuch. aus d. bot. Laborat. d.
Univers. Gottingen, II, Berlin, 1881.

426 SECOND PART.—MYCETOZOA.

eye. The microscope reveals a constant change of outline in all the branches, some-
times in the form of a slight undulating movement, sometimes of an unceasing
protrusion and withdrawal of small pointed tentacle-like processes or pseudopodia.
Some of these pseudopodia or single flat projections of the main branches swell into
a knob at the free extremity and presently grow into larger branches, while in another
part branches diminish in size and gradually sink back into the main stem. Here
two branches grow out towards each other till they touch one another, and then
coalesce and anastomose; there a branch becomes constricted at some point and
divides into two. By these processes a plasmodium may separate into several parts,
and several plasmodia may be united into one; but according to Cienkowski’s and
my own observations union never takes place between plasmodia of different species.
Branches of every degree and every size participate in the movements, and the smaller
the branch the more active is its movement. The alternation in the movements
takes place at all points alike in the plasmodium, but the protrusion of branches
predominates on one side, the retraction on the opposite. Hence there is often an
active advancing movement, a locomotion of the plasmodium in the direction of the
greater protrusion, and the anterior portion of the whole body which leads the way
in the advance assumes the form of a system of branches with swollen extremities,
which spread out like a fan and are connected together into a reticulated structure
by numerous and constantly changing anastomoses; in other words it becomes a
flat surface pierced so as to form a sieve or net and traversed by the stronger
branches like swollen veins, its margin being thickened and uneven (Fig. 185).

The inner substance of the plasmodium is also subject to a variety of active
movements and displacements which are seen to be directly connected with the
amoeboid movements, but sometimes appear to be independent of them. First there
are the previously mentioned swellings and sinkings of the marginal hyaloplasm, the
locality of which is constantly changing. Secondly stream-like displacements of the
inner granular plasm with change of speed and direction. The varying breadth of
‘the marginal hyaloplasm shows that there is a constantly varying pressure of the
granular mass in the direction of the periphery. The movement in the interior takes
place in the form of streams which occupy the whole breadth of a branch, or run in
narrow threads through the surrounding substance which is apparently motionless.
The movements are chiefly directed towards the swelling and advancing extremities
of the branches, into which the granular mass streams in, the alternating backward
flow being weaker and less copious. The reverse takes place in branches which are
being withdrawn. But movement and streaming may be constantly alternating with
rest in the interior of the plasmodium without this prevailing and directly perceptible
connection with the amoeboid change of shape.

Further details with respect to these phenomena must be sought in monographs
and in the physiological treatises which have appeared since my first work on this
subject. See also below in section CXXVII.

The surface of the plasmodia of the Physareae which I have examined is
covered with a soft shiny envelope, which is not distinctly defined on the outside but
_ is quite distinguishable from the marginal layer. It forms a border round the thicker

branches which is often more than 0,01 mm. in thickness, and is in itself colourless
and pellucid but is often covered with small particles of soil which adhere to it.

CH.VIII.— MORPHOLOGY AND COURSE OF DEVELOPMENT. —MYXOMPCETES. 427

It consists of a sticky substance which swells in water and contracts in alcohol and
is scarcely coloured by iodine, and must therefore be different from protoplasm. It
passively follows the movements of the plasmodium. Portions of it often remain
adhering in the form of thin films of mucilage to spots from which a plasmodium has
moved away. This envelope is often very thin round the rapidly swelling extremities
of the branches, and cannot be distinguished at all round slender pseudopodia,
having been either pierced through by them or extenuated by their advance till it is
no longer perceptible.

The plasmodia of the Stemoniteae, Trichiaceae, Ceratieae and Lycogala have
in the main the same structure and power of movement as those of the Physareae, but
they never have the granules of calcium carbonate and therefore usually appear to be
much more finely granular than in the Physareae. The dark-blue or violet-brown
plasmodia of the Cribrariae and Dictydium contain large brown granules of some
organic substance, but have as yet been very insufficiently examined. The plasmodia
of Lycogala which live in rotten wood are surrounded by a thick colourless membrane;
I observed a similar membrane some time ago in Arcyria punicea. Itis not yet ascer-
tained how this membrane behaves in the movements. I was unable to see it in former
years in specimens of Lycogala grown in water. I found the plasmodia of Stemonites
fusca, when it issues from the substratum to form its sporangia, surrounded by a stout
envelope, the inner and thicker layer of which is‘coloured a dark blue by iodine
while an outer thin layer remains colourless. All the plasmodia last mentioned are
inconspicuous bodies, the stouter branches of which in Arcyria punicea are not more
than 16 a in thickness, in Lycogala not more than 24 ». They live for the most part in
the interior of rotten parts of plants, especially rotten wood, and are not visible to
the naked eye till they come to the surface to form sporangia.

Section CXX. Transitory resting-states. Those stages of the development
in Myxomycetes which have the power of motion are able to pass into resting-states
and to return again under favourable conditions to the state of movement. Three
resting-forms are at present known: microcysis, thick-walled cysts (Cienkowski) and
sclerolia.

It appears from cultures of Chondrioderma difforme that these transitory
resting-states are not necessary members of the course of development. Their
formation would seem to take place only when the development of the swarm-cells into
plasmodia or of the plasmodia into sporangia is interrupted by insufficiency of food,
by slow desiccation, or by slow cooling to below a certain minimum. But there are
a number of observations which also point to other at present unknown causes.
The state of movement is restored when the bodies after desiccation are again placed
in water of the proper temperature.

The term microcyst was given by Cienkowski to the resting-state of the swarm-
cells. Under the conditions above mentioned these cells assume the form of spheres
which are smaller than the spores and are surrounded by a very delicate colourless
membrane, as in Perichaena liceoides according to Cienkowski, or are without a
membrane but provided with a very firm marginal layer. In other respects their
structure remains the same as that of motile swarm-cells, only that the vacuoles in
many cases disappear and the protoplasm becomes more dense. The swarm-cells of
Didymium praecox and D. difforme encysted in this way and perfectly dry retain

428 SECOND PART.— MYCETOZOA.

their vitality for more than two months ; how soon life becomes extinct in them has
not been ascertained. If placed again in water, they return to the motile swarming
state, and the more quickly the shorter the period of desiccation. Those of
Perichaena liceoides cast off their outer membrane under these conditions.

The thick-walled cysts and sclerotia are resting-states of plasmodia. The
former were examined by myself in isolated cases in Fuligo, and Cienkowski
followed them through the whole course of their development in Perichaena liceoides.
The cysts were formed by young plasmodia in both species. According to Cien-
kowski’s observations the plasmodium divides by the rending of its branches into
pieces of very unequal size, which draw in their processes and assume the shape of
smooth spheres. Then a membrane of considerable thickness forms on the surface
and becomes rough and wrinkled and assumes a dark-brown colour. Within this
membrane the protoplasm contracts still more and forms on its surface a second
coat with a double-contour. If placed in water after drying for several weeks the round
bodies remain first of all unchanged for some weeks, and then the protoplasm begins
to display slow undulating movements and at length swells up, makes a hole in the
surrounding coats, and slowly emerges from them with all the characters of a
plasmodium.

The sclerotia are the resting-states of full-grown plasmodia. They have been
observed in Didymium leucopus and D. difforme, D. Serpula, Fuligo, Physarum sinu-
osum, Perichaena liceoides and in a number of Physareae which have not been more
precisely determined, and perhaps also by Corda in Stemonitis!. Some of them are
the forms on which Persoon based his fungal genus Phlebomorpha.

When their formation begins the plasmodium draws in its slenderer processes
and assumes the shape of a sieve-like plate, or in Fuligo of a small tuber a few
millimetres in diameter and with irregular prominences on its surface ; the granules
become distributed uniformly through the fundamental substance, the solid ingesta are
extruded, the movement gradually ceases, and the whole body breaks up into an
innumerable quantity of roundish or polyhedric cells with an average diameter of from
25 to 40 a. The body becomes at the same time of a wax-like consistence and
dries into a brittle horny mass, resembling the sclerotia of many Fungi.

Each cell chiefly consists of a firm protoplasm which incloses vacuoles varying in
size and number, and a pigment and granules distributed in the same manner as in the
motile plasmodia, and shows a sharply limited marginal layer. Nuclei are there no
doubt, though they have not as yet been observed. In the strongly developed sclerotia
of some species (Fuligo, Didymium Serpula) the protoplasm is surrounded by a distinct
colourless membrane, which in both the species mentioned shows the reaction of
cellulose with iodine and sulphuric acid or with Schulze’s solution. The membranes
are firmly attached to one another, either immediately or, as in Fuligo, by a homogenous
intermediate substance which softens in water. In small weakly developed specimens
of the above species and in all sclerotia that have as yet been examined in other
species, as for instance in Didymium difforme, no distinct membranes can be seen
round the protoplasm.

1 Icon. Fung. II, Fig. 87 2.

CH.VIII.—MORPHOLOGYF AND COURSE OF DEVELOPMENT.—MYXOMYCETES. 429

The outer surface of the sclerotia is usually covered by alayer of the same
homogeneous substance with a capacity for swelling which is found between the cells
in Aethalium. Upon it there are also in many cases (Fuligo, Didymium) scales or
grains or crystals of calcium carbonate which must have been excreted during the
formation of the sclerotia.

If a mature and dry sclerotium is placed in water it at once swells up, and its
cells coalesce once more into a motile plasmodium often in from six to fifteen hours,
in older specimens after a longer interval which may last some days. Where
membranes of cellulose are present they are first dissolved. The process begins at
the surface and advances towards the centre.

If single cells of a sclerotium are watched, contractile vacuoles are seen to form
in them a few hours after they are moistened, and protrusion of motile branches and
pseudopodia and the creeping forward movement all begin as in plasmodia. “Where
moving cells meet and. touch they coalesce; if moving cells encounter cells that
are still at rest, they absorb them. In this way a large plasmodium is ‘gradually
formed containing many sclerotium-cells which it has engulphed. These phenomena,
which were first observed by Cienkowski in Didymium difforme, explain the formation
of the plasmodium from the compact sclerotium. In plasmodia recently formed
from sclerotia in which the cells have not separated from one another we always see
a number of unaltered or evidently dead sclerotium-cells carried along by the stream
of granules; these become presently less frequent and at length entirely disappear ;
they must therefore be either dissolved or they coalesce with the substance of: the
plasmodium.

Sclerotia are known to retain their vitality in a dry state for 6-8 months.
Fuligo and Didymium Serpula are known from several direct observations to persist
during the cold and dry season of the year in the condition of a sclerotium, and pass
again into the motile state with damper and warmer weather. Vitality did not last
more than 7-8 months in most of the observed cases, though sclerotia of Didymium
Serpula lived more than a year (others only 7 months), and Léveillé? quotes an obser-
vation to the effect that. a sclerotium of a Myxomycete had been known to return to
the motile condition after having been kept for zo years.

Section CXXI Development of sporophores and sporangia. The de-
velopment of the plasmodia closes with the formation of spores within receptacles,
sporangia, or on the outside of sporophores. The latter are confined to the
Ceratieae, the former are common to the rest of the Myxomycetes. We may
therefore with Rostafinski distinguish the Ceratieae as exosporous, all other
Myxomycetes being endosporous.

The sporangia of the endosporous forms are vesicles, which are usually about
ımm. in height but may considerably exceed that size, and rise with or without a
stalk above the substratum or lie upon it in the form of round or flat tubes. Their
stricture when they are fully formed will be more minutely described in section
CXXII. Their development from the plasmodium is divided into the successive
sections of forming, development of wall, separation of the spore-plasm, and lastly

1 Ann. d. sc. nat. ser. 2, XX, p. 216.

430 SECOND PART.—MYCETOZOA,

Sormation of the spores and of the capıllittum which in many genera accompanies the
spores. These processes also have been most thoroughly and satisfactorily examined
in the lime-containing Physareae, Rostafinski’s Calcareae, and will be described from
them in this place.

In the simpler cases of forming of sporangia, which we may examine first, either
an entire plasmodium spread out on its substratum becomes transformed into a
sporangium, or it divides into a number, often a large number, of pieces, each of
which suffers transformation. This transformation is the result of the same kind of
amoeboid movement of the protoplasm as that which causes the change of shape and
place in the vegetating plasmodium, with the difference only that in the forming.
of sporangia the masses of protoplasm by drawing in their branches become
constantly broader and rounded off and at length assume stable forms. The spor-
angia which lie flat on their substrata are in conformation simply portions of a
plasmodium which have been thus contracted and thickened. Erect sporangia on a
narrow or stalk-like base begin as node-like swellings on a branch of the plasmodium,
and gradually rise to their ultimate form as the surrounding protoplasm flows into
them and assumes an upward direction.

The soft envelope which surrounded the retracted branches of the plasmodium
remains sticking to the substratum and there dries up; but there appears in its place
round the young sporangium a firm membrane evidently produced by its further
growth, and this membrane constitutes the wall of the sporangium which often grows
to a considerable thickness. In the stalked forms the sporangium-wall begins to
strengthen and get firm at the base of the stalk, and the process advances upwards.
The zones of the membranes successively growing stronger serve as a support for
the upward moving protoplasm.

During the forming of the sporangia the solid ingesta which are present in the
plasmodium begin to be expelled from it, When a sporangium has assumed its
definitive form the spfore-plasm is separated off inside it. The granules of calcium
carbonate, the pigment and perhaps other substances also, which at present are not
precisely determined, are eliminated from the true protoplasm. In Physarum and its
nearest allies they move to the wall and become imbedded in it or attached to it; or
they collect into lumps of various shapes which are arranged differently inside the
sporangium in different species, and by the formation of a membrane round them
are soon converted into vesicles containing calcium carbonate or pigment (Fig. 191).
In Didymium and the forms nearest to it the calcium carbonate granules in the plas-
modium are dissolved and in this state are expelled from the sporangium, and while
the granules disappear inside, the outer surface becomes covered with crystals of the
salt. In Didymium Serpula the only well-known species of this group with coloured
plasmodia, the yellow colouring matter is gathered up at the same time inside the
sporangium into round lumps, which are then inclosed in pigment-vesicles by the
formation of membranes round them. The protoplasm which remains after these
substances have been removed from it is for the most part a colourless body with small
granules uniformly distributed through it. By staining numerous nuclei are made
visible in it. This plasm has been termed spore-plasm, because much the larger part
of it is used for forming spores; as soon as it has got rid of the foreign substances in it
its nuclei rapidly increase in number, and at length the whole mass divides simul-

CH.VIII.— MORPHOLOGY AND COURSE OF DEVELOPMENT.—MYXOMYCETES. 431

taneously into polyhedral portions with rounded corners, each of which encloses a
nucleus, and becoming invested with a firm membrane ripens into a spore. The spores
when first formed are somewhat larger, never smaller, than when they are mature.

A comparatively small portion of the spore-plasm is expended in forming
the capıllitium, a filamentous structure to be described more fully in section
CXXII, which spreads through the cavity of the sporangium and is connected
both with the wall of the sporangium and with the vesicles containing pigment
and calcium carbonate. The capillitium always appears before the spores, and
all the parts in the earliest state in which they have been examined are seen to
be formed and arranged exactly as when they are mature, only they are at first
extremely delicate and gradually acquire their subsequent firmness. These points
will be noticed again below.

Fuligo, the ‘ flower of tan,’ agrees with Physarum in all other points, but shows
a variation in the phenomena described above in the forming of the sporangia; here
a number of plasmodia collect together from every side and become fused together
into a narrow dense reticulum with the shape of a cushion, which may come to be
twelve inches in breadth and one in thickness or may remain quite small. The
strands of this reticulum anastomose in every direction with one another. Then all
the spore-plasma passes after its separation into the inner portion of the reticulum
which swells proportionately, and then acquires the structure of the sporangia of
Physarum; the vesicles with calcium and colouring matter remain behind in the
peripheral layers, where they collapse and dry up forming a calcareous crust or rind
from one to several millimetres in thickness.

Of the rest of the endosporous Myxomycetes, ihose, that is to say, which do not
belong to the Physareae, it may be confidently affirmed that the development of the
sporangia from the beginning of forming is thoroughly like that which has just been
described. The development of the spores is in all cases the same. Strasburger
succeeded in following the multiplication of the nuclei, which precedes the formation
of the spores, in Trichia fallax through all stages of the division, and ascertained their
morphological agreement with the divisions of the nucleus in many other vegetable
and animal cells. The case is the same also with the formation of the capillitium,
with some limitations naturally arising from generic differences. The elimination of
contained substances which leads to the formation of the spore-plasm is less copious
or there is none at all to be seen, as is the case in Stemonitis in all states
which have at present been examined, because the substances secreted in the
one case are wanting from the first in the other. The very first stages in the forming
of sporangia are in most instances imperfectly known because of the difficulty of
procuring plasmodia in the vegetating state. What is known of it in most genera
with simple sporangia, as Trichia, Arcyria, Dictydium, &c., corresponds with the fore-
going description of the Physareae. On the other hand the large and often thick-
walled spore-receptacles of Lycogala, Reticularia, Lindbladia and others are formed
by such an accumulation and intermingling of numerous plasmodia as has been
described in the case of Fuligo. Rostafinski applies the collective name aethalium to
all bodies which originate in these combinations of plasmodia. Little more is known
of the processes of differentiation in their development than can be concluded from
the mature state.

‘

432 ° u SECOND PART.—MYCETOZOA.

:The conformation of the sporangia in Stemonitis runs differently in one respect
from that of all other known forms. The slender threads of the plasmodium, which
lives in rotten wood, unite at first into large cylindrical or ellipsoid bodies of
homogeneous protoplasm, which rest their broad surface on the substratum. Then
a hollow cylindrical firm central column is separated off in the protoplasmic
body, and rises vertically from a membranous base resting on the substratum,
advancing by acropetal growth (Fig. 186 a, 4). The mass of protoplasm, the
longitudinal axis of which is traversed by the column, stretches at first at the same
time in the same direction; but it afterwards loses hold of the substratum at its base
and clinging to the central column moves on it a certain distance upwards till at

a

ce
FIG. 186. Stemonitis ferruginca. a a com- FIG, 18. Ceratium hydnoides. Forming of
mencing sporangium with the first beginning of the sporophores on plasmodia which have come to the
central column. & sporangium which has reached surface of a piece of wood. Successive stages of
its mature form, capillitium and spores not yet formed: development according to the letters a—c; ¢ the
Both figures represent specimens in optical longitu- mature state. After Famintzin and Woronin, about

dinal section hardened in alcohol and then rendered 3 times the natural size,
transparent in glycerine. zmagn.ıztimes, 015 times.

length it becomes stationary and developes into a sporangium in the usual manner
(Fig. 186 4). The sporangium is supported on the lower portion of the central
column which is laid bare by the upward movement of the protoplasm, as on a stalk.
Other genera allied to Stemonitis behave in a similar manner. Further details must
be sought in the different monographs.

The plasmodia of the ectosporous Ceratium hydnoides come forth to the
surface from the interior of the rotten wood which is their habitation to form their
spores (Fig. 187). Here they appear at first to the naked.eye as white cushion-shaped
bodies (Fig. 187 a); examination with the microscope shows that these cushions are
formed of countless microscopically slender plasmodium-branches, united together in
every direction into a net-work of narrow meshes, such as is shown in Fig. 188 a. The
meshes are filled with a hyaline homogeneous gelatinous substance of watery
consistence, which forms a thin coating on the surface of the net-work. To form
the sporangia cylindrical often dichotomous outgrowths, resembling the spikes of a
Hydnum and growing to be a few millimetres in length, rise erect from the surface
of the cushion (Fig. 187 4, ce). The whole body of protoplasm moves into these
outgrowths, leaving only a thin flat layer to connect it with the substratum. During

CH.VIIT.—-MORPHOLOGY AND COURSE OF DEVELOPMENT.—MVYXOMYCETES. 433

these movements:the branches of the plasmodia all change their previous distribution
through the whole of the thickness of the body and creep to the periphery, where they
form a net-work stretching only in the direction of the surface and formed of threads
which become successively broader and meshes growing narrower and narrower
(Fig. 188 a). The whole is covered on the outside by a thin layer of the hyaline
protoplasm which alone forms the whole of the inner portion of the body. When
these processes are completed, the net-work of protoplasm breaks up simultaneously
into numerous polyhedral portions of nearly uniform size (Fig. 188 4). They contain
each a nucleus, become flattened from without inwards, and remain grouped in a
simple layer which follows the surface like an epithelium. Then each of these proto-
plasmatic bodies begins at once to grow convex towards the outside, and to lengthen
out at right angles to the surface of the whole body into the shape of a sphere borne
on a slender conical stalk (Fig. 188 4). A delicate membrane is formed at the
same time within which all
the protoplasm passes through
the stalk into the spherical
expansion at the extremity.
The latter then becomes in-
vested all round with a söme-
what thicker membrane with
an ellipsoid outline, and thus
becomes a mature spore which
is readily detached from the
empty;hyaline stalk. The entire
gelatinous sporophore under-
goes no further changes, but
in most cases soon dissolves
and disappears.

The other known ecto-

. FIG. 188. a Ceratium hydnoides Piece of a sporophore in the act of forming:
Se een
ee ee
the species just described only woronin. a magn. about 68 times, b 120 times.
by the yellow colour and by
the shape of its sporophore, which resembles in form the hymenium of a Polyporus
(see page 288).

The development of the sporophores and receptacles as just described runs its
course rapidly if the conditions are favourable. According to a series of observations
on spontaneously developed Physareae, species of Trichia, Stemonitis and others, the
complete development from the commencement of the formation to maturity requires
an interval on the average of about 12 hours; the development is quicker or slower in
particular species, or according to the temperature and moisture of the environment.

The sporophores of Ceratium are perfectly formed according to Famintzin
and Woronin in the course of a summer night. The entire development of the
species may also be accomplished very rapidly. Cienkowski obtained in four days
fully formed plasmodia of Chondrioderma difforme when grown on microscopic
slides, and these formed sporangia on the fifth day.

[4] Ff

434 SECOND PART.—MYCETOZOA.

Delay may of course occur where the conditions are unfavourable. That the
several species behave very differently in these respects is shown by the fact, that
many of them, Trichia rubiformis, T. clavata and T. varia for example, are observed
to form their sporangia almost entirely during a short portion of the yearly period
of vegetation. The biological relations of most of the species require further
examination. :

Section CXXI. The structure of the mature sporophores is n all cases
essentially the same as in the Ceratieae. The ripe sporangia in the majority of the
endosporous genera, which show a great amount of variation in different species, must
be described from a few of the typical forms, which have been known for some time.
For special peculiarities the reader is referred to monographs and especially to
that of Rostafinski.

We must first distinguish between the simple sporangium, which proceeds from
one plasmodium or from a part of one plasmodium, and the aefhalum, as Rostafinski
understands that term, which is formed from large combznations of plasmodia.

1. It has been already said that the mature sporangia in most Myxomycetes
are round or elongated, stalked or sessile vesicles one to a few millimeters high ; less
frequently, as in Didymium serpula, Trichia
serpula and Licea flexuosa, P., they are
cylindrical or flattened tubes forming a
network and lying on the substratum.

The wall of the sporangium is formed
of a membrane which in constitution re-
sembles the cellulose-membranes of plants.

ae EE ae It is either 2 structureless hyaline and

Keen BX), A ripe sporangium divided longitudinally SOMelimes, as in Diachea and some species
25 times. of Physarum, an extremely delicate mem-
brane, or it is thick and firm and evidently
stratified, as in Leocarpus vernicosus, Craterium, Trichia varia and others; in the
Physareae included in the old genus Diderma it is even double, that is, it is
differentiated into two layers which may be easily separated from one another
and which do often separate of themselves. Projecting thickenings of different
dimensions in the shape of warts and ridges occur in some cases, on the
whole of the surface for example of the thick olive-brown outer layer of Licea
flexuosa, and on the inner surface of the base of the sporangium of Arcyria
incarnata, A. punicea and A. nutans. The whole of the inner surface of the
membrane in Cribraria and Dictydium shows projecting thickenings in the form of
flattened ridges connected together into a delicate net-work. The membrane is
colourless or coloured in various shades of violet, brown, red and yellow according
to the genus and species; it is usually continued at the point of attachment of the
sporangium into an irregular‘ membranous expansion formed of the dried envelopes
of the plasmodium, and securing the sporangium to the substratum.

The stalks, except in the Stemoniteae, are tubes usually with a thick wall, which
is wrinkled and folded lengthwise and is continued above into the wall of the
sporangium, Its lumen is either in open communication with that of the sporangium,

CH.VIII.—MORPHOLOGP AND COURSE OF DEVELOPMENT.—MYXOMFCETES. 435

as in Trichia and Arcyria, or is separated from it by a transverse wall; if the septum
is convex upwards it is termed the columella or central column (Fig. 189). The cavity
of the stalk varies in breadth in different species and contains nothing but air, as in
Physarum hyalinum, or is filled in the manner which will be described below.

The structure of the membrane of the sporangium in most of the species which
contain no calcium, Licea, Perichaena, Cribraria, Arcyria, Trichia, &c., is usually such
as has now been described. In some of these it also contains coloured granules of an
organic substance, the nature and origin of which have yet to be ascertained; these
granules are imbedded in the stronger ridges of thickening matter in Cribraria and
Dictydium ; in Perichaena liceoides they lie singly or in groups on the outer surface.
The olive-brown outer layer of Licea flexuosa shows an irregularly granular structure
throughout the entire thickness.

FIG. 190. Physarum leucophaeum, Fr. aspor- FIG. 19%. Physarum leucophaenm, Fr. Piece of the wall of a
angium seen from without. 5 sporangium divided sporangium with tubes of the capillitium attached and spread out in
in half and the frame-work of the capillitium water; @ points of attachment of the tubes of the capillitium; 5 calcium
exposed by removal ofthe spores, Magn. 25 times. carbonate-vesicles; to the right on the margin a calcium carbonate-

vesicle on the wall, The rest of the wall is covered with calcium
carbonate-granules singly or in groups. Magn. 390 times.

On the other hand the wall of the sporangium in most of the Physareae and their
allies (Calcareae of Rostafinski) is incrusted, wholly or in part according to the genus
and species, with the calcium carbonate eliminated in the separation of the spore-
plasm. In a number of genera, of which Physarum may be taken as a representative
(Figs. 190, 191), the calcium carbonate appears in the form of small round granules
which either lie isolated and more or less deeply sunk in the wall, or form dense
irregular accumulations on its inner surface. In many species the granules of calcium
carbonate, especially those that are collected together in heaps, are surrounded by the
extruded colouring matter mentioned above, which is yellow in Physarum aureum,
P., Ph. sulphureum, A.S. and other species, or more rarely reddish-yellow as in Ph.

Ff 2

436 SECOND PART,—MYCETOZOA.

psittacinum, Ditm. The heaps of granules appear in this case to the naked eye as
small coloured patches or warts on the dry sporangium ; where there is no pigment
they are white.

Didymium (Fig. 189) is distinguished by a crystalline covering of calcium
carbonate like hoar-frost formed of stellate glands and small single crystals on the
outer surface of the sporangia. The Diderma-forms mentioned above, which partly
approach Physarum and partly Didymium, have the wall of the sporangium differ-
entiated into a delicate inner layer which is free from or contains very little calcium
carbonate, and an outer layer, a brittle incrustation of lime, consisting of round or
crystalline fragments of calcium carbonate closely crowded and held together by
a small quantity of organic matter, which when the calcium carbonate is dissolved
remain behind as a delicate membrane.

Calcium carbonate eliminated from the plasmodium in a granular or crystalline
form is imbedded in unusually large quantities in the basal wall of sessile sporangia
and in the wall of the stalk in stipitate sporangia in many of the Calcareae. In the
latter case a considerable amount of the salt often occurs inside the stalk and
columella, where it is not unfrequently associated with irregular lumps of some
organic substance and to a great extent fills up the cavity as in Didymium leucopus,
Fr. (Fig. 189) and Diachea.

The cavity of the sporangium is either filled exclusively with the numerous spores,
as in Licea and Cribraria, or, as in most genera, tubes or threads of different forms
occur between the spores and constitute the capzllitium. The capillitium of Physarum
and its nearest allies (Figs. 190, 191) consists of somewhat thin-walled non-septate
tubes which spread their branches in every direction and combine them into a net-
work, Many branches run from the periphery of the net-work to the wall, and are
firmly attached to it by their usually funnel-shaped extremities. The tubes’are swollen
and inflated at the nodes of the net-work, forming the calcium carbonate-vesicles
mentioned above and sometimes also containing a pigment. All the Calcareae have a
capillitium which is everywhere firmly attached by the extremities of its branches to the
wall of the sporangium in the manner here described. In Didymium (Fig. 189), with
which genus Spumaria and Diachea agree in this respect, the capillitium consists of very
slender threads, from 1-3 to 2 in breadth in D. nigripes, Fr. and D. leucopus, Fr.,
as much as 2-4 » in D. farinaceum, which are cylindrical or slightly flattened, solid or
with an indication of a cavity in the form of a single line in the longitudinal axis, and
usually of a dirty violet-brown colour in the broader parts. The threads are usually
quite free from calcium carbonate; in a few cases, as in D. physaroides, they inclose
single angular granules or crystals of calcium carbonate. They run in Didymium from
below upwards most commonly straight or sinuous in a radial direction from the
insertion in the stalk to the upper and lateral wall, their anastomoses usually forming
an acute angle. D. Serpula is remarkable for the numerous round pigment-vesicles
which adhere to the threads of the capillitium, and like the spores have a violet-
brown membrane, but are from four to six times their size, being sometimes
50p in diameter.

.The capillitium of the Trichiae and Arcyriae consists of tubular threads which
have no deposits of calcium carbonate, and are either not attached at all to the wall of
the sporangium or only at a few definite points. In Arcyria (Fig. 192) it is a non-

CH.VIII.—MORPHOLOGY AND COURSE OF DEVELOPMENT.— MYXOMYCETES. 437

septate tube separating into countless branches, which form a net-work by their
anastomoses. The thick homogeneous wall has the same colour as the sporangium-
membrane, and its outer surface is usually furnished with projections which take the
form either of small spikes or warts, or of annular or semi-annular transverse ridges
according to the species. In Arcyria punicea and A. cinerea the capillitium is
anchored by the blind ends of branches of the net-work which are grown to the lower
part of the wall of the sporangium. In most species (A. incarnata, A. nutans) it is
nowhere in connection with the wall, but is fastened loosely by a few branches from
the tubes, which descend into the stalk and are squeezed in between the cells which fill
it up and which will be described presently. So long as the capillitium is inclosed in
the sporangium its branches are all bent in every direction and folded up, and the meshes
with their four, five or more sides are narrow and irregular. When the sporangium

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BNW

——

FIG. 192. a, 5Arcyria tncarnata, P. inoutline. « a ripe spor- FIG. 193. a, 6 Trichia fallax, Fr. ahalf ofa
angium closed. 5 the same open with the expanded net-work of capillitium-tube. 4 superficial view of a spore.
the capillitium. ¢, d Arcyria Serpula, Wigd. (4. anomala, De ¢, @ Trichia chrysosperma, DC. De By. ¢ ex-
Bary.) c portion of a capilitium. daspore. = and 5 magn. 20, tremity of a capillitium-tube. @ spore. Magn.
¢ and d 390 times. 390 times,

opens on reaching maturity, the branches straighten themselves in most species
(A. cinerea is an exception), the meshes become broader and the circumference of
the net-work many times larger (Fig. 192 a, 4), and the structure never returns in any
degree to its original form.

The capillitium-tubes of Trichia and Hemiarcyria which have frequently been
described are united in the latter genus (H. rubiformis, H. clavata, &c.) into a net-work
with branches which at the same time have free extremities. In Trichia (Fig. 193)
they are quite free, and either simple or furnished with single short branches, their
extremities being usually pointed, and in some species, as T. fallax, long and attenuated.
The length of the free tubes varies usually between -3 mm. and 7 mm., the average
thickness being from 5 to 7 a; longer and much shorter tubes occur here and there.
The transverse section is usually circular. Their contents appear to be pellucid, but

438 SECOND PART.—MPCETOZOA.

treatment with potash discloses an axile thread of an opaque substance, which turns
yellow with iodine and is a remainder from the contents of the young tubes. The
membrane of the tubes is thick but not evidently stratified, with a different degree of
flexibility in different species, and coloured with different shades of yellow, red and
reddish brown. It shows in all cases ridge-like projections or thickenings on the
outer surface which run spirally round the tubes and often appear as folds in the
membranes, since the lumen of the tubes is broader along their course and constricted
in the intervals between them. The direction of the spiral as it ascends is with few
exceptions, one only of which has come under my notice in Trichia varia, the same
as that of the hand of a watch. The number of ridges varies with the species, being
2in T. varia and 3-5 in T. fallax and T. chrysosperma. Variations of number in
the same tube are partly due to bifurcation of the ridges, partly to the fact that
some of them do not reach the end of the tube. In some species, as Hemiarcyria
rubiformis, the back of the ridge is beset with spike-like processes. Trichia chry-
sosperma has a number of smaller slender ridges running between the spiral ridges
and parallel to the longitudinal axis of the tube, and connecting each pair of spiral
ridges in a scalariform manner (Fig. 193 ¢). The tubes of the capillitium lie mixed up
together in great numbers and folded many times in the sporangium. If they are
dried or their water is extracted by alcohol, they stretch themselves out but never
become quite straight; if moisture is restored they acquire still stronger curvatures,
and the same phenomena are repeated each time that the moisture is changed. This
hygroscopic motility and the spiral ridges recall the elaters of the Hepaticae, and
the tubes of Trichia have therefore received the name of elaters.

Certain species of Trichia and Arcyria, some of which have been already
named, have the cavity of the stalk of the sporangium filled with vesicles or cells,
which resemble spores but are larger and incapable of germination. They may very
well be receptacles of excreta like the calcium carbonate-vesicles of the Calcareae.

The sporangia of Stemonitis, Comatricha, Enerthenema, and their allies are also
distinguished in the mature state by certain peculiarities. They are borne on the
stalk described above as being of the thickness of a hair or bristle and narrowing
gradually upwards ; this stalk passes through the base of the sporangium and occupies
its longitudinal axis as a central column (columella), and either reaches the apex
where it expands in Enerthenema into a membranous disk passing into the wall, or
comes to an end below the apex and splits as it were into threads of the capillitium,
Stalk and columella are hollow tubes, the cavity of which contains air and lumps of
some organic substance. The wall is thick and marked with longitudinal wrinkles,
and is coloured a dark brown throughout or has an outer layer colourless. The base
of the stalk expands into an irregular membranous disk which rests on the substratum
(Fig. 186). The primary branches of the dark-brown capillitium spring with a broad
base from the whole outer surface of the columella, or as in Enerthenema only from
the disk-like expansion at its extremity. These branches ramify repeatedly in every
direction, and the ramifications become united into a net-work which has everywhere
a large number of meshes. A large number of slender branches run from the meshes
of the circumference only, and become attached by their free extremities to the wall
of the sporangium. The structure of the stronger branches of the capillitium is like
that of the columella, but their lumen is not in communication with the lumen of the

CH.VIII.—MORPHOLOGY AND COURSE OF DEVELOPMENT.—MYXOMFCETES. 439

columella; the slenderer branches resemble those of Didymium and Diachea. The
wall of the sporangium is a simple and usually very delicate membrane, and like all
other parts is free from deposits of calcium carbonate.

The capillitia which have now been described, though of many and apparently
very different kinds, must nevertheless from the data before us be all regarded as
peculiar membranous or parietal formations secreted or excreted from the protoplasm.
Their material composition is not accurately known and will be briefly noticed again
in the sequel, but it would appear to be not essentially different from that of the
thicker portions of the outer wall of the sporangium to which they are sometimes
attached. In the Calcareae (Physarum, Didymium, &c.) their substance or wall passes
continuously into the wall of the sporangium of which they appear simply as processes,
and thus closely resemble the branching bands of cellulose which spring from the
outer wall of a cell of Canlerpa and stretch into the interior of the cell. That they
are at the same time quite or partially hollow and take up excreted matter into their
cavity, especially into the calcium carbonate-vesicles before described, is in favour of
this conception. The wall-processes accordingly serve partly as supports partly as
receptacles of the excreta. All that is known of their development (see page 431) is
likewise in harmony with this view, which finds important support in Strasburger’s
recent observation that the development of the capillitium is essentially the same in
Trichia as in the Physareae, though the tubes in the latter lie free and with a blind
termination in the spore-plasın or between the spores, and are so like some vegetable
cells that they were long taken for cells. According to Strasburger the tubes of the
capillitium of Trichia fallax are formed by secretion of a membrane from the
round spaces in the protoplasm which are of the same shape as the tubes, and are
filled with a fluid (?) and have no nucleus. This would not prevent their also serving
as receptacles of any excreta. What is true of Trichia may certainly be assumed of
Arcyria and the species allied to it. The exceptional features in the Stemoniteae
require therefore no further discussion.

2. The structure of the aethalium in the mature state has been sufficiently
explained in the description of the history of the development of the most common
form Fuligo varians, the Aethalium septicum of authors, which will be found on
page 431. The body, which has the shape of a cake or cushion, is covered with a
brittle rind some millimeters in thickness, which is at first of a golden yellow colour
but afterwards becomes pale or cinnamon-coloured, and is continued all round the
margin into a membranous expansion lying on the substratum. This rind consists of
portions of the combined plasmodia which have collapsed and retain only the calcium
carbonate and pigment; within it is a dark-gray mass finely speckled with yellow
and readily crumbling to powder, and formed of a fine net-work of tubes, which
may be nearly ı mm. in thickness and which have exactly the same structure as
the capillitium of the sporangium of Physarum. es

Other aethalia are connected by their structure with Didymium, Diachea,
Licea, &c., as Fuligo is with Physarum; but some like Reticularia umbrina require
further examination.

The round sessile aethalia of Lycogala epidendron, Fr., which are as large as a
pea or hazel-nut, have a very peculiar structure. They resemble small sporophores
of the Lycoperdaceae. Their surface is covered by a paper-like membrane or rind

440 SECOND PART.—MYCETOZOA. --:

(peridium), the outer side of which is irregularly warted, while numerous tangled
threads, a capillitium, stretch from its inner surface into the cavity of the body which
is filled with spores. The rind is composed of two portions having a layer of finely
granular mucilage between them and separating readily from each other. ‘The
inner portion in the surface-view is perfectly homogeneous or finely punctated; seen
in section it is an evidently stratified membrane about 8 a in thickness and of a
bright brown colour. The outer and much thicker portion on the other hand is formed
chiefly of a weft of cylindrical tubular branched threads disposed in several irregular
layers; the thickness of the threads is usually 20-33 a, and their walls are stratified
and thick, sometimes 10 a in thickness, the outer lamellae consisting of a homogeneous
jelly while the innermost layer is of firmer consistence and provided with slit-like pits
or reticulate thickenings. Numerous branches of these rind-threads bend inwards,
and piercing through the inner rind appear as threads of the capillitium in-the central
cavity. Here they have only the innermost lamellae of their membrane which is
pitted or thickened in a reticulate or sometimes annular manner, the outer lamellae
coming to an end in the inner rind. The thickenings project outwardly in the form
of ridges which have the appearance of wrinkles and vary in height and breadth,
being often very flat. The threads of the capillitium, which are often compressed
and riband-like, branch and anastomose copiously. Finally the warts on the outer
surface of the rind are thick-walled closed vesicles filled with a densely granular
substance. These vesicles are undoubtedly remains of plasmodia filled with excreted
substances, the whole body having been composed when young of their dense and
uniform reticulum. The threads of the outer rind appear to be the thickened and
subsequently emptied membranes of other peripheral plasmodial strands ; the develop-
ment of the inner part is imperfectly known.

The space not occupied by the capillitium is entirely filled with spores in all the
sporangia of the Myxomycetes. All parts-are kept moist with water till they are
mature; then the water evaporates, and the wall of the sporangium dries up and
opens in various ways to release the spores. The mode of dehiscence is generally
very irregular ; the wall as it dries becomes brittle and breaks up into small pieces at
the least touch or quite of iis own accord. This is the case in almost all the Physareae,
and in Fuligo, Spumaria, Stemonitis and others. In the Cribrarieae the portions of
the membrane which have not been thickened fall to pieces, the thickened portions
remaining as a delicate lattice work. The rind in Lycogala and Reticularia tears
irregularly and perhaps spontaneously at the apex. In Chondrioderma floriforme the
outer layer of the wall of the sporangium splits from the apex into stellately diverging
lobes. In Trichia, Hemiarcyria and Arcyria the dehiscence and the extrusion of the
spores is assisted by the expansion of the capillitium caused by desiccation, and in
the first genus by the hygroscopic movements also. The wall either opens spon-
taneously by an annular fissure in the lowest part of the sporangium, as in Arcyria
punicea and A. cinerea, or in the upper part as in Hemiarcyria rubiformis, or by
irregular fissures (Fig. 192 a, 6) either spontaneously or when subjected to a slight
amount of violence. The various monographs must be consulted for further details.

The ripe spores vary in size in the different species, their diameter being about
5 # in Lycogala epidendron and 15 » in Trichia chrysosperma. In many species
single abnormally large spores often occur amongst the typical ones. They are

CH. VIII.—MORPHOLOGY AND COURSE OF DEVELOPMENT, —ACRASIEAE. 441.

always roundish in form when saturated with water, but as they dry they often become
concave or boat-shaped, like the spores of many Fungi (see page 106). They are
provided with an episporium, a thick unstratified membrane which in a few cases, as
in Trichia fallax and some species of Didymium, is two-layered, and is provided in
many species with a thinner spot which is perforated in germination and may there-
fore be termed a broad germ-pore. The outer surface of the membrane is smooth or
furnished with projections of definite shape (Figs. 192, 193) according to the species’
and genus, and is usually of a deep colour, being violet or violet-brown for instance
in all Calcareae and Stemoniteae, and yellow and red in the Trichiaceae. The pro-
toplasm enclosed by the episporium has been already described.

As. regards the material composition of the membrane in sporangia,
capillitium and spores, we know that it behaves towards reagents in a szmlar
manner to cuticularised plant-cell-membranes and to spore-membranes in the Fungi,
but analyses of it are still wanting. The blue or violet colour of cellulose with
iodine does not usually appear; but Wigand and myself found exceptions to this
tule in Trichia furcata, Wigd., T. pyriformis and T. varia, in which the innermost-
layers of the walls of young sporangia become a dirty blue with iodine and sulphuric
acid; the membranes also of the spores and of the cells which fill the stalk of Arcyria
cinerea, A. punicea and A. nutans and those of the spores of Lycogala epidendron all
turn a beautiful blue with the same reagents. Further details will be found in the
special treatises which will be named below.

In the foregoing account’ of the Myxomycetes the nomenclature which Rostafinski
introduced in his monograph has been substituted for the older nomenclature, or
unequivocal synonyms only of Rostafinski’s names have been retained. The most
frequently recwring names are:

Calcareae = Physareae of my earlier works.

Fuligo varians = Aethalium septicum of former authors.

Perichaena liceoides = Licea pannorum, Cienk.

Chrondrioderma difforme = Didymium Libertianum, Fres., the ‘ Physarum album ’

of Cienkowski.
Licea flexuosa = Licea serpula, Fr., &c.
Further details respecting the nomenclature and the structure of the spore-

receptacles should be sought in Rostafinski’s writings: see also Just’s Jahresbericht,

NS for 1873.
N ACRASIEAE.

Section CXXIII. The Acrasieae, which live on the excrements of animals and on
decaying parts of plants, commence their development like the Myxomycetes with the
escape of a swarm-cell from a spore. The swarm-cell always remains in the form
which has amoeboid creeping movements, never assuming that which has cilia and
the hopping movement. After multiplying greatly by successive bipartitions the
swarm-cells unite again, many hundreds in number oftentimes if the development has
been vigorous, in order to form spores. But they do not for this purpose coalesce
into plasmodia. The swarm-cells are piled up one on another without coalescing,
remaining distinct and artificially separable from one another though closely crowded
together, and forming bodies of definite shape which rise perpendicularly above the
surface of the substratum, and in which every one or the majority of the swarm-cells
assumes the structure of a spore of a Myxomycete, having usually a delicate membrane

442 SECOND PART.—MY CETOZ OA,

and being of the average size of from 5 to 10 u. These spore-heaps resemble small
sporangia of a Myxomycete, but have no distinct wall; the spores are only held
together and surrounded by a slight structureless enveloping substance.

Inthe Guttulinae, which have been carefully examined by Cienkowski and Fayod,
the development, apart from the possible resting-states which will be described below,
is limited to the above phenomena. The ripe spore-heaps are formed only of spores.
They lie on the substratum as round or elongated bodies of the size of a pin’s head
and with the appearance of small white, yellow or red drops.

In the other genera of the group Dictyostelium and Acrasis a division of labour
appears among the heaped up swarm-cells. When the body which is formed by them
begins to rise above the substratum, those which are in its central line form firm
outer membranes at the expense of their protoplasm, and are gradually changed into
chambers formed of cellulose and filled with a transparent substance. They remain
in close union with one another without interstices, and being built up on or against
one another in a single row or in several rows in large Dictyostelia, they form a stalk
which rests on the substratum and traverses the middle of the body somewhat in the
manner of the stalk in the sporangium of Stemonitis (Fig. 186 a). This stalk grows
for a time acropetally by addition of new elements. The aggregate of swarm-cells
surrounding the stalk lengthens in proportion as the stalk grows and becomes corre-
spondingly narrower, and ultimately separates from the substratum as the stalk ceases
to grow; it then creeps up the stalk leaving it bare and proceeds to form its spores at
the apex. This process also is to some extent illustrated by Fig. 186 which represents
Stemonitis. In Dictyostelium the spore-masses borne on the stalk resemble in the main
those of the Guttulineae. According to Van Tieghem the spores are arranged in
Acrasis in rows one above another like beads in a rosary. For further details the’
reader is referred to Van Tieghem’s and Brefeld’s publications.

In Guttulina protea, Fayod found that the swarm-spores grown in a fluid and
remaining isolated may undergo the change into spores of the form and structure
which they have normally in the state of aggregation. When the conditions are
unfavourable for the development these swarm-cells form a thick outer membrane in
a complicated manner, and pass into a state which corresponds to the encystment of
the swarm-cells of the Myxomycetes (page 427) and may therefore be termed a
transitory resting-state. Van Tieghem observed a different mode of encysting in
Acrasis and Dictyostelium when the conditions were unfavourable ; a swarm-cell put
out a number of processes or arms one after another, which separate from the
parent-cell, round themselves off and become invested with a membrane.

In Brefeld’s first work on Dictyostelium the development was to some extent
incorrectly described, the dense aggregations of swarm-cells which develope into
the stalked spore-masses being supposed to be plasmodia, that is, products of the
coalescence of swarm-cells, and the rest of the phenomena being interpreted in ac-
dance with that supposition. Van Tieghem’s correction of this mistake in 1880 was

cautious but at the same time clear and complete, and Brefeld has recently (1884)
published a full confirmation of this correction.

AFFINITIES OF THE MycetTozoa.

Section CXXIV. In investigating the affinities and homologies of the Mycetozoa
which have now been described, we must distinguish between the Myxomycetes which

CH. VIIL—MORPHOLOGY AND COURSE OF DEVELOPMENT.—AFFINITIES. 443

form plasmodia by coalescence of swarm-cells and the Acrasieae which do not
form plasmodia. The two groups are evidently closely related to one another, the
only important difference between them being the coalescence of swarm-cells in the
one group and their firm aggregation only in the other. It is easy to conceive
that the one form of development has proceeded directly from the other, either
the Myxomycete form from that of the evidently more simply Acrasieae, or in
the converse order.

The group of the Mycetozoa differs distinctly from the Fungi which have been
the subject of the first part of this book in all such characteristics as do not belong
to all organisms alike, and the descriptions already given of both kinds of plants
render any further explanation of the point unnecessary ; their connection also with
other known plants is still more remote. The difference would not be less decided,
if the Mycetozoa were without their remarkable amoeboid movements, for such
movements are observed in other vegetable cells which have not a firm membrane.
The characteristic mark of separation lies in the formation of plasmodia or
aggregation of swarm-cells.

It is obvious moreover according to our present knowledge that the Mycetozoa
are the superior terminal member or the two terminal members of a series of forms
or developments which commence elsewhere. The most highly differentiated sections
of the group, the Calcareae, Trichiae, Lycogala and others, give evidence of no close
affinity with any more highly differentiated group; in other words, like the Gastro-
mycetes with which they were classed by earlier botanists, they do not connect with
any group above them. Hence in enquiring after their affinities we must be content
with searching for a possible connection with an inferior group, and for the simpler
forms from which they have proceeded.

When we seek for such a connection among the forms with which we are
acquainted, we find it impossible to establish any strict homologies, and we are
limited to the observation of resemblances in form, structure and mode of life. Sucha
course of unprejudiced comparison leads us by a very short step to the naked
‘ Amoebae’ of the zoologists, especially in Biitschli’s sense, as the starting point,—
organisms with bodies having the amoeboid movements of the swarm-cells of the
Myxomycetes, which multiply, as far as we at present know, by successive bipartitions
without forming plasmodia, and which may pass singly and without aggregation or
coalescence into states of rest not essentially different in their characteristics from those
of the spores of the Myxomycetes. Guttulina is really a naked Amoeba of this kind,
and is distinguished from other known forms only by the aggregation of its spores.
Guttulina protea, mentioned above as forming solitary spores, differs in this respect from
the Amoebae ; it may be classed as well with the naked Amoebae as with the Acrasieae,
and forms therefore a perfect connecting link with the Amoebae. Thus on the one hand
the more highly differentiated Acrasieae join on at once to Guttulina, and on the other
a short step further brings us to the type of Myxomycetes which form plasmodia, in
which coalescence of swarm-cells into a plasmodium and redivision of the plasmodium
into spores take the place of their aggregation. Forms like Guttulina may have
developed phylogenetically in two divergent directions, on the one hand into the more

1 Bronn’s Thierreich, see below, page 454.

244 SECOND PART.—MPCETOZOA.

highly differentiated Acrasieae, on the other into forms which produce plasmodia.
Plasmodiophora, which will be further noticed below, is perhaps one of the simplest
representatives of the latter kind, though this must remain uncertain for reasons
which will be stated. In the group of the Myxomycetes the type becomes highly
differentiated. -

From these naked Amoebae with which the Mycetozoa are connected in the
ascending line, the zoologists with reason derive the copiously and highly developed
section of the shell-forming ‘Rhizopods,’ as they are understood by Fr. E. Schulze and
Biitschli, though the course of their ontogenetic development is still imperfectly
known. And since there are sufficient grounds for placing the Rhizopods outside the
vegetable and in the animal kingdom, and this is undoubtedly the true position for the
Amoebae which are their simpler and earlier forms, the Mycetozoa which may be
directly derived from the same stem are at least brought very near to the domain of
zoology. It has been already pointed out that the Mycetozoa show only a slight
agreement, either in the general course of their development or in the characteristic
features of its separate stages, with organisms which are of.undoubted vegetable origin,
whether they be Fungi or plants other than Fungi; the agreement, with the exception
of the few cases in which cellulose makes its appearance, is confined to phenomena
which are common to all organised bodies. It is exactly in the species, which like
Lycogala and Fuligo are most like the Fungi, that the agreement is of the smallest
possible amount, being confined to purely external marks such as those between birds
and winged insects. On these various grounds, which have been worked out at
different times with greater or less clearness according to the state of our knowledge,
I have since the year 1858 placed the Myxomycetes under the name of Mycetozoa
outside the limits of the vegetable kingdom, and I still consider this to be their true
position.

We may further enquire whether closer ties of relationship do not appear at
some point or other between the group of the Mycetozoa at their lower limits and
members of the vegetable kingdom. In the search for these and judging by known
facis, we find that the only forms which we can take into consideration are the
Chytridieae which have no mycelium, as Synchitrium, Olpidiopsis, Rozella and Woronina
(see sections L-LII). It has been already more or less distinctly stated that these forms
are nearly related to the Mycetozoa. They agree with the Myxomycetes, first in the
peculiar circumstance that the entire vegetative body is finally transformed into one
many-spored sporangium, secondly in the fact that their spores and the vegetative
body itself in the young state have the power of amoeboid movement for a longer or
shorter time. But these are phenomena which are common to them and many other
Thallophytes, with which no one ever has supposed or ever will suppose them to have
any near affinity, Botrydium for example or Porphyra ; it is plain also that they have
been appealed to from a wish to find some group of undoubtedly vegetable forms in
which the Myxomycetes could be included. Of the characteristic phenomena of
development in the Mycetozoa, the Chytridieae mentioned above show nether the
aggregation of the Acrasieae, nor the formation of plasmodia by coalescence of swarm-
cells. If the term plasmodium has in their case been used to describe bodies
originating in the growth of a single spore, this arose either from an erroneous idea
(Cornu), or it is a misuse of the word, for though Chytridium in its young state often

CH. VIII.—MORPHOLOGY AND COURSE OF DEVELOPMENT.—AFFINITIES. 445

shows the amoeboid movement of a plasmodium, it has not the character which is
involved in the origin of a plasmodium; this is the case too with the spore of
Porphyra which also has the power of amoeboid motion.

There is therefore no real ground for assuming a direct relationship with these
Chytridieae, whether they do or do not form a natural group with the other species
which produce mycelia, a question which, as was explained in Chap. V, must for the
present remain undetermined.

It is a totally different question whether it is possible to suppose a common
origin for these particular Chytridieae and the Mycetozoa, and consequently a more
remote and indirect relationship. The comparison of the facts known to us shows it
to be probable, as Biitschli points out, that the starting point of the naked Amoebae
of the zoologists is to be sought in the group of very simple organisms known as the
Flagellatae, and a study of the swarm-spores of the Mycetozoa leads to the same
view, for in the stage of their existence when they are furnished with cilia they have
all the characters of the simpler Flagellatae. But not only the Chytridieae which
produce no mycelium but all the group show such close affinity to the Flagellatae,
that they might if necessary be phylogenetically derived from them. But this is true
also of the entire assemblage of the simple Algae, with which it was sought to connect
the Fungi in the sections of Chapter V. We may as well place the Volvocineae
with the Flagellatae as with the Chlorophyceae, if we prefer that arrangement, and
no one will doubt the close affinity which exists between them and the rest of the
undoubted Chlorophyceae.

If then we distinctly separate the Mycetozoa from the Fungi, and are prepared
even to draw the boundary line which divides the two organic kingdoms between these
groups, we do not thereby deny that members of the two divisions may approach very
near to the group of the Flagellatae, towards which all the evidence shows that. the
two kingdoms converge, and thereby approach also very near to one another.

The purpose of the foregoing remarks has been to do for the Mycetozoa what
was previously done for the Fungi, namely to establish their affinities on the foundation
of the facts of which we are at present in possession, or speaking more boldly to give
the true account of them. Such an attempt whenever made must be made with the
material then at hand. Ifthe foundation of facts changes with the progress of our
researches a fresh attempt must be made.

The views of botanists as to the position of the Mycetozoa in the system, have
already varied much in the course of time. The older view just noticed above, which
placed the Myxomycetes with the Gastromycetes on the strength of a mere resem-
blance between the mature sporangia in the two groups, has now only a historical
interest. Further remarks on this point will be found in my monograph of 1864.

The ideas with regard to the place of the Mycetozoa in the natural system which
were expressed by Famintzin and Woronin in their beautiful work on Ceratium do not
at the present day call for discussion. Cormu in 1872 endeavoured to connect them
with the Chytridieae, chiefly by assuming the formation of plasmodia in the genera of
Chytridieae which do not produce a mycelium; but we have already shown that this
‘assumption is without foundation. The opinion represented in Brefeld’s work on
Dictyostelium (page 20), that this organism might connect the group of the Myxomycetes

with the Fungi through the Mucorini, is refuted by a comparison of the course of
development in the two groups. The more recent utterances of the same writer on the

446 SECOND PART.—MYCETOZOA.

point under consideration presuppose on the one hand their connection with the Fungi
as something ascertained, and on the other hand in dealing with the affinities of
the Fungi so leaves the firm ground of definite facts for the regions of speculation,
that they cannot be admitted into a discussion which keeps close to facts. The view
lately promulgated by J. Klein in his treatise on Vampyrella is essentially the same as that
which would derive the Myxomycetes and the Chytridieae from a common stem lying
outside the series of Fungi. It sees the form, from which Myxomycetes, Chy-
tridieae and Rhizopods all descended, in the Vampyrellae which belong either to the
Rhizopod-type (or Heliozoa-type) or to that of the Myxomycetes, but it can hardly be
said to have any foundation in facts; it should have gone somewhat further back to
the Flagellatae, as has been suggested above.

DOUBTFUL MYCETOZOA.

Section CXXV. I here exclude from the ranks of the true Mycetozoa a few
forms or groups of forms, some of which have been occasionally mentioned in the
preceding sections. These forms so far as they are known have many points of
resemblance with the Mycetozoa, but either our knowledge of them is imperfect, or
else they depart so far in certain points from the typical Myxomycetes and Acrasieae,
that it is better to have their position in the system for the present undetermined. At
the same time we may properly give a brief enumeration and description of them in
this place.

Bursulla crystallina, Sorokin, is, according to the author’s account of it, a very
small Myxomycete growing on horses’ dung, with an ovoid stalked sporangium 0.03
mm. in height, and forming eight spores by simultaneous division. The spores before
they become invested with a firm membrane escape from the swollen apex of the
sporangium in the form of swarm-cells without cilia but capable of amoeboid move-
ment, and subsequently coalesce in indefinite numbers and form plasmodia, which in
their turn become fashioned each into a single sporangium or into a group of several
sporangia according to their size. Sorokin saw no nucleus in the swarm-cells at the
ordinary vegetative temperature ; on the other hand a nucleus was observed when the
sporangia were exposed to a very low temperature (as low as —27°C). The develop-
ment was in other respects the same; we may conclude therefore that the nuclei of
the swarm-cells had been overlooked in the first-mentioned case. We may venture
therefore a step further and assume that when a swarm-cell with a nucleus encounters
one which is supposed to be without a nucleus, the two coalesce into a cell which
forms a membrane and passes into a resting state as a kind of oospore; and that
after hibernation the protoplasm issues forth from the membrane and becomes
fashioned into an ordinary sporangium. This may in fact be simply a case of the
encystment of small plasmodia. Apart from the peculiar features which require
examination we may really have a small Myxomycete before us in Bursulla.

The course of development in Haeckel’s pelagic Protomyxa aurantiaca
entirely resembles that of a Myxomycete. ‘Protoplasmic body, a plasmodium of an
orange-red colour, (always?) formed by coalescence of several swarm-spores, 0.5-1
mm. in diameter; with very many thick arborescently branched pseudopodia which
form a net-work by frequent anastomoses. Resting state, a spherical lepocytode with
a diameter of 0.15 mm., and a thick structureless envelope (cyst). Swarm-spores

CHAPTER VIII-—MORPHOLOGYF AND COURSE OF DEVELOPMENT. 447

pear-shaped, conical at the smaller end and running out into a very strong flagellum ;
movement that of the swarm-cells of the Myxomycetes. The spores when they come
to rest creep about in the manner of the Amoebae.’ Such is Haeckel’s diagnosis.
This organism differs from the Myxomycetes chiefly in the absence of firm spore-
membrane, and in the circumstance that neither cell-nucleus nor division of the swarm-
cells has been observed. Myxastrum radians, Haeckel, also a marine form and dis-
tinguished by the presence of silica in the spore-membranes, appears to be nearly
allied to Protomyxa.

Cienkowski’s Vampyrellae are organisms with amoeboid movement which live
on Algae and Diatoms. Some like Vampyrella Spirogyrae and V. pendula suck the pro-
toplasm and chylorophyll-corpuscles from out of the living cells of species of Spirogyra
or Oedogonium, when they have pierced their walls, while V. vorax embraces the entire
cells of Diatoms, Desmids and similar forms with their pseudopodia, and absorbs them
into its own substance. In both cases the reception of a certain quantity of food is
followed by a period of rest, a smoothing of the surface of the body and the excretion
of a delicate firm membrane. In this state of rest the bodies which have been
absorbed are digested, that is are dissolved till there remain only comparatively minute
portions of the protoplasm which have assumed a brown colour, and in the case of
Vampyrella vorax of the membranes. Next follows the excretion of the undigested
substance from the living protoplasm, the division of the latter into usually 2-4 swarm-
cells and their escape from the membrane; the two processes go on simultaneously,
the division being effected while the spores are escaping at 2-4 separate points. Then
according to J. Klein from 2-4 swarm-cells, seldom more, at once coalesce again
and form a plasmodium, which repeats the process just described of absorption of
food and subsequent formation of swarm-cells. In addition to this course of develop-
ment resting cysts may also be formed, in which case the body which has come to
rest inside the membrane excretes undigested remains of the food, and then without
forming 8warm-cells excretes a new membrane. The subsequent fate of these cysts
is still unknown. Other transitory states of rest, as in the small cysts of the
Myxomycetes, may occur within the periodic course of development described above,
and no coalescence may take place, the cells passing singly through the swarming
state as above but not forming plasmodia.

Cienkowski’s Nucleariae appear to be just like the Vampyrellae in the
course of their development and in their manner of life. They are distinguished
from them by the presence of nuclei, which are said to be wanting in the Vampy-
rellae. Coalescence into plasmodia has not been observed in them, but it is not
excluded by the ascertained facts.

Cienkowskis Monas Amyli has motile swarm-cells provided with two cilia,
and a number of these cells surrounding a starch-grain may coalesce into small
plasmodia. The plasmodium forms a membrane, and after its substance has increased
in size at the expense of the starch-grain it produces a large number of new swarm-
cells by simultaneous division. It is said also that a single swarm-cell may spread
itself round a grain of starch without uniting with others to form a plasmodium,
and thus become the starting-point of the development which was described above.

An exactly similar course of development has been observed in Klein’s
Monadopsis and Cienkowski’s Pseudospora and Colpodella, except that the latter

448 SECOND PART.—MFCETOZOA.

two genera, as far as isat present known, do not form plasmodia, but each swarm-cell
after absorbing food becomes the mother-cell of a new generation of swarm-cells.

Plasmodiophora Brassicae is parasitic on the roots of cruciferous plants,
especially species of cabbage, and causes large swellings on them. An amoeboid’
swarm-cell with cilia escapes from the round thin-walled spore in water, and pene-
trates without first undergoing division into the epidermis of the young root and from
thence into the parenchymatous tissue. Then the cells of the host become greatly
enlarged and large bodies with amoeboid movements make their appearance in them ;
but it could not be certainly determined whether these bodies were due to the growth
of one swarm-cell, or to the coalescence of several swarm-cells as in the Myxomycetes,
or possibly to a modification of the protoplasm similar to that which occurs in
Rozella (see page 395). Ultimately the entire protoplasm contained in a cell of the
parenchyma becomes motionless and divides simultaneously into a very large number
of spores of the character stated above, and in this case also without previously
forming a special membrane.

Finally Zopf" appears to include all sorts of lower organisms with amoeboid
movements together with some of the forms last described under the name of ‘lower
slime-Fungi.’ This use of the term does certainly not correspond with the meaning
hitherto assigned to it, and to avoid any misunderstanding I say very distinctly
that this application of the term and therefore also the discussion of any other forms
than those which have now been mentioned cannot be admitted in this place.

CHAPTER IX. MODE OF LIFE OF THE MYCETOZOA.

Section CXXVI. Germination. The spores of the Mycetozoa, in which
the germination has been observed, are able to germinate from the momentithat they
are ripe. Some retain the power of germination for a long time if protected from
injury ; many Calcareae, for example, Physarum, Didymium, Chondrioderma, Peri-
chaena liceoides, retain their vitality 2-3 years, some, as Physarum macrocarpum
according to Hoffmann, eve for 4 years. In Trichia varia and T. rubiformis
vitality lasted according to “express observations only 7 months; in other species of
Trichia and allied forms it appears to be extinguished ata still earlier period.

The requisite conditions for germination in most known forms are the usual
spring and summer temperature of our temperate climates and a sufficient supply of
water. The majority germinate readily when placed in pure water, well developed
fresh material often in a few hours. Nutrient substances dissolved in the water do
not hinder germination; this at least was found to be the case in Fuligo and
Chondrioderma. The Ceratieae and such Acrasieae as have been examined do not
germinate in pure water, but only in a suitable nutrient solution. The like necessity
and the use of unsuitable solutions may account for the want of success which has
attended the attempts hitherto made to procure the germination of their spores of the
Cribrarieae and Tubulina.

1 See Biolog. Centralblatt, Bd. III, Nr. 22.

CHAPTER IX.—MODE OF LIFE OF THE MYCETOZOA. 449

The requisites for germination are the same in sclerotia and cysts as in
spores, as was stated above on page 428, where also will be found all that is known
of the external causes which lead to the formation of these states.

Section CXXVII. Some account has necessarily been already given in section
CXIX of the phenomena attending the life of the plasmodia. For many
general questions which here come under consideration, the reader is referred, in ac-
cordance with the purpose of this book, to works on general physiology, and especially
to Pfeffer’s Physiology, vol. II, chap. 8 and Stahl’s latest publication on the subject,
and the account here given must be confined to a short review of their mode of life.
This has been investigated chiefly in the plasmodia of the Physareae, Fuligo especially,
which are readily procured. What is known of other forms appears to agree
with the accounts given of the.Physareae, but. requires. more exact investigation.

Movement of plasmodia. The internal causes of the changes of shape, of
the protrusion ‘and withdrawal of processes and the interior streaming of granules,
which are attendant on the organisation of the protoplasmic body and are
to a great extent unknown to us, cannot of course be discussed in this place.

The most important external causes of the movements of the plasmodium and
of the changes in its form are, the z//umination, the distribution and movement of the
water in the substratum, the chemzcal nature of the environment, and the conditions of
temperature. It is uncertain to what extent purely mechanical influences are also
operative. Rosanoff’s former assumption of ,geotropic movements has proved to be
without foundation. We may therefore, in accordance'more or less with the general
terminology of the movements of growth, speak: of phenomena of Aeliotropism,
Aydrotropism and rheotropism, trophotropism and thermotropism.

Heliotropism. A vegetating plasmodium stretches out its branches and
reticulations uniformly in every direction on uniformly moistened surfaces, such as
paper steeped in water and kept in a dark or equably but faintly illuminated chamber.
If. the intensity of the illumination is increased, the power of movement, according to
Baranetzki, is generally diminished, and if the amount of illumination is different in
different portions of the expanded surface, the branches are drawn in from the bright
side and others are put forth towards the darker side; the plasmodium also moves
towards the darker side. The direction of these movements is independent of the
direction of the beams of light which fall-on the plasmodium, being determined only
by the intensity of the illumination.

Hydrotropism. : If while all other conditions are uniformly favourable the
water is unequally distributed in the substratum, the vegetating plasmodia, if not on
the point of forming spores, withdraw from the drier spots when the dryness has
reached a certain degree and wander towards the moister.

Rheotropism. If a stream of water is made to flow slowly through a
moistened porous substratum, such as filtering paper or strips of linen cloth, the
plasmodia which are vegetating on the moist surface wander in the direction cf
the stream, without regard to the particular direction in space in which it moves.

Trophotropism. Vegetating plasmodia spread out on surfaces which yield
little or no nutriment move towards bodies which contain nutrient substances as

[4] 6g

450 SECOND PART,—MFCETOZOA,

soon as they are offered to them, here too without regard to the direction in space in
which the movement has to be made. If the plasmodium of Fuligo which usually.
lives in tan is spread out on the moist vertical wall of a glass, it remains in this
position, other things being the same, as long as the surface of the glass is covered
with a film of pure water. If an infusion of tan is added to the water, in such a
way that the plasmodium is touched by it at one spot only, it begins to move rapidly
towards this spot and gradually puts out numerous branches which dip into the
infusion. A small piece of tan placed close to a plasmodium under similar conditions
is quickly seized by a number of freshly protruded branches. The similarity in the
effect of the fluid containing the infusion of tan and the solid piece of tan shows that
it can only be due to chemical constituents of the tan; what these are has not been
precisely ascertained.

If a plasmodium comes into contact on one side with other bodies dissolved
in water, the opposite effect is produced, namely repulsion of the plasmodia. Even a
solution containing } or 3 per cent. of grape sugar produced this effect at first in
Stahl’s experiments, but the plasmodium by degrees became accustomed to it and
behaved to it as to the infusion of tan. A sudden change in the concentration of the
saccharine solution, either by increasing it to a certain amount (2 per cent.) or
diminishing it, gives rise to similar phenomena to those first described. Stahl
observed the same repulsions in experiments with saline solutions.

If oxygen is excluded on one side, a movement takes place, as might have been
expected beforehand, towards the side where oxygen is admitted.

Thermotropism. If the substratum, other conditions being the same, is
unequally warmed on different sides, the plasmodium moves, at least within the limits
of temperature observed in Stahl’s experiments (+ 7° to 30° C.), towards the side which
is most highly warmed.

Most of the phenomena observed in spontaneously vegetating plasmodia,
especially their creeping hither and thither and in and out, according to the time of
the year and the state of the weather, on the substratum of vegetable remains, such as
leaves, tan and the like, may be explained very simply from the experimental results
here recorded.

A further fact established by Stahl must be added here in explanation of another
and very remarkable phenomenon, namely that in the plasmodia of Fuligo and some
species of Physarum, in which the point could be examined, the reaction against
locally unequal distribution of water in the environment changes with the age. The
plasmodia are positively hydrotropic, that is wander from the dry to the moister spots,
other things being equal, during the vegetative stage, but become zegazivelh
hydrotropic near the moment of formation of sporangia, that is they move from the
moister to the drier spots.

This movement also takes place without regard to the mere direction in space,
and so may be upwards or downwards &c., and it explains the general fact that almost
all plasmodia, as soon as they are ripe for forming sporangia, move to comparatively
very dry spots on the surface of the moist substratum, often travelling a considerable
distance, before being transformed into sporangia; it explains also, according to
Stahl’s observations, the elevation of the commencing sporangium in a direction at
right angles to the comparatively moist substratum.

CHAPTER IX.—MODE OF LIFE OF THE MYCETOZOA. 451

Further investigation is necessary to determine whether other causes also may
not assist in certain cases to give rise to the latter phenomenon ; the question also,
whether the peculiar characters of plasmodia under discussion may not change at a
certain period of their development in relation to other things, as well as to
hydrotropism, has still t0 be examined, especially with reference to a statement
of Hofmeister‘ that certain plasmodia moved towards the side of strongest
illumination.

To the movements which have now been described must be added one more
which requires a brief consideration. It was stated above on page 425 that small
solid bodies are engulphed in the substance of the plasmodia, at least in the Cal-
careae or Physareae. This is effected by definite movements; the surface of
the plasmodium rises cushion-like round the bodies which are in contact with it,
and the margins of the raised part gradually run together over them and cover
them. j

This phenomenon occurs in the plasmodia, as soon as they have been formed by
coalescence of swarm-cells, but not in the swarm-cells themselves, if we put aside
certain isolated observations on Dictyostelium which have yet to be confirmed, It is
not confined to any particular spot of the plasmodium, and may continue till
sporangia begin to be formed; then the foreign bodies which have been absorbed
and are still present are all ejected, some of them even at an earlier period. ‘All this
shows, that the solid bodies are not simply squeezed into the soft and passive
substance of the plasmodium; but that there is a reaction of the plasmodium
in response to the stimulus which it experiences from contact with them.

Substances of various kinds are taken in this way into the substance of the
plasmodium: fragments of dead vegetable cells, spores of Fungi and of the
Myxomycetes themselves, sclerotium-cells of Myxomycetes, grains of starch, small
portions of colouring matters if brought near the plasmodium.

All these substances it should be observed consist of organic compounds, and it
is highly probable that some of them at least supply food to the plasmodium which
has engulphed them. It is not certainly ascertained whether entirely indifferent
inorganic substances are absorbed by it. The question therefore remains
unanswered, whether the movements of engulphing are caused by the purely
mechanical stimulus of contact, or by certain chemical qualities of the substance to be
engulphed. In the latter case the phenomenon would rank immediately with the
movement in the direction of nutrient bodies described above, and both would be
special cases of a more general law of reaction in response to chemical irritants, An
old observation of my own supports the view that the reaction not only is or may be
dependent on a definite chemical quality in the body which causes the stimulus, but
that plasmodia of different kinds react unequally on the same stimulation. A number
of pieces of carmine were absorbed by Didymium Serpula, scarcely any by Chondrio-
derma difforme.

Section CXXVIII The process of nutrition takes place only in the
amoeboid states of the Mycetozoa, in the swarm-cells therefore and the plasmodia.
All the better known Myxomycetes in their actual primary adaptation are saprophytes ;

1 Pflanzenzelle, p. 20. -
Gg2

452 SECOND PART.—MYCETOZOA.

they live on dead organic and especially vegetable substances, of course with the
necessary ash-constituents, and are found therefore chiefly in accumulations of
dead parts of plants—leaves, tan, rotten wood, and the like. What definite chemical
substance does actually and usually serve or is fitted to serve as nutrient material
to the Myxomycetes is a question which has not yet been thoroughly examined.

The facts recorded above show that the food is taken in during the swarm-cell
condition only in the fluid state or state of solution, and this is also the case, at least in
most instances, with the plasmodia. That it is so. appears, to say the least, extremely
probable by the behaviour of the plasmodia of Fuligo to’ the extract of tan, as shown
by Stahl’s experiments quoted above. This agrees with the observation that
plasmodia of Chondrioderma difforme may be obtained’ from spores in watery
infusions of vegetable substances though no solid bodies are supplied to them, and
lastly with the fact that solid ingesta have never béen found in the plasmodia of
certain species, as Lycogala, though it must be allowed that these have not been very
thoroughly examined. ;

On the other hand we see solid bodies taken up by the plasmodia which have
been more particularly described above, among others by Chondrioderma, and some
of them at least again thrown out. The body taken into the plasmodium is often more
or less perfectly dissolved. It has already been stated that the sclerotium-cells
of a species engulphed by its own plasmodium gradually disappear and pass into
the substance of the plasmodium, but it is uncertain whether this is a case of actual
dissolution of the body introduced, or of a coalescence with the body which absorbs
it, like that of the swarm-cells or the branches of the plasmodium. In the plasmodium
of Didymium Serpula which were fed with carmine, the fragments of carmine were to
some extent at least dissolved ; they were repeatedly carried along in the stream of
granules, and in twenty-four hours’ time were enclosed each in a vacuole filled with a
clear red solution. This continued for several days. On the other hand the
Chondrioderma mentioned above showed no signs of dissolving the few fragments of
carmine which it received into its substance. In experiments instituted’ by Dr.
Wortmann a number of starch-grains were taken in by plasmodia of Fuligo, and they
showed deep corrosions in the course of from two to three days. This shows
the presence of a ferment capable of dissolving starch and confirms Kühne’s previous
determination. A ferment which acts upon cellulose must be present, at least during
the passage of the sclerotia of Fuligo into the motile condition, because the cellulose
membranes are rapidly dissolved during that time. Krukenberg has ascertained the
presence of a peptonising ferment’.

These facts all point to the conclusion that the solid ingesta are to some extent
at least appropriated as food and digested, the undigested remainder being then cast
out. We have no exact physiological investigations of these questions and of others
which are connected with them. So far as plasmodia devour and digest living bodies,
the name of saprophytes can only be applied to them with some modification of its
ordinary mean.

Some of the forms which were classed above as doubtful Myxomycetes, Bursulla
for example, are saprophytes in their mode of life. The account given above ‘of

: ? Unters. d. physiol. Instit. z. Heidelberg, II, p. 273. See also Reinke cited on p. 52.

CHAPTER IX.— MODE OF LIFE OF THE MYCETOZOA. 453

Plasmodiophora shows that it is, in the terminology employed in the Fungi, an en-
dophytic parasite which greatly deforms its host. Vampyrella and the forms with
a similar mode of life must no longer be termed parasites; they devour other
organisms wholly or partially, absorbing the objects which they admit into their sub-
stance by the same or nearly the same movements as those by which plasmodia
take in their solid ingesta.
Literature :—
E. FRIES, Systema mycologicum, III, 1829.
A. DE Bary, Die Mycetozoen (Zeitschrift f. wiss. Zoologie, Bd. X, 1859, and 2nd ed.
Leipzig, 1864). For a variety of details and full accounts of the literature of the

subjects the student is referred to the second edition of my work and to the following
publications: - says

L. CIENKOWSKI, Zur Entwicklungsgeschichte der Myxomyceten, and Das Plasmodium
in Pringsheim’s Jahrb. f. wiss. Bot. III, 325 and 400.

J. T. ROSTAFINSKI, Versuch eines Systems der Mycetozoen (Diss. Strassburg, 1873) ;—
Id., Slucowce (Mycetozoa), eine Monographie, Paris, 1875 (in Polish), with full lists
of works on the subject down to 1875.

J. ALEXANDROWITSCH, Ueber Myxomyceten (in Russian), Warsaw, 1872.
STRASBURGER, Zur Entwickelungsgeschichte der Trichia fallax (Bot. Zeit. 1884, p. 305).

.A, FAMINTZIN u. M. WORONIN, Ueber Ceratium hydnoides ü. C. porioides (Mém.
Acad. Pétersbourg, XX, No. 3, 1873).

O. BREFELD, Dictyostelium mucoroides (Abh. d. Senckenb. Ges. VII, 1869) ;—Id.,
Untersuchungen aus der Gesammtgebiete der Mycologie, I, Leipzig, 1884.
L. CIENKOWSKI, Ueber einige protoplasmatische Organismen (Guttulina). See Just’s
' Jahresber. for 1873, p. 61.
VAN TIEGHEM, Sur quelques Myxomycétes A plasmode agrégé (Bull. Soc. bot. France,
27 (1880), p. 317.
V. Fayop in Bot. Ztg. 1883. Guttulina protea.
L. CIENKOWSKI, Beiträge zur Kenntniss der Monaden in M. Schultze’s Archiv f.
Mikrosk. Anatomie, I, p. 203, tt. XII-XIV. See also Regel in Bot. Ztg. 1856, p. 665.
’ M. WORONIN, Plasmodiophora Brassicae in Pringsheim’s Jahrb. XI, p. 548, tt. 29-34.
E. HAECKEL, Monographie der Moneren (Jenaische Zeitschr. IV, p. 64).
F. E. SCHULZE, Rhizopodenstudien (Arch. f. Mikrosk. Anatomie, XI and XIII, p. 9).
J. KLEIN; Vampyrella (Bot. Ztg. 1882 and Bot. Centralbl. XI (1882), Nr. 5-7).
- .N. SOROKIN, Bursulla crystallina (Ann. d. sc. nat. ser. 6, II, p. 40, t. 8).

-S, ROSANOFF, De l’influence de l’attraction terrestre sur la direction des Plasmodia
des Myxomycétes (Mém. Soc. de Cherbourg, XIV, p. 149).
. J. BARANETZKI, Influence de la lumiére sur les Plasmodia des Myxomycetes (Mem.
Soc. de.Cherbourg, XIX, p. 321).
E. STRASBURGER, Wirkung des Lichtes und der Wärme auf Schwärmsporen. Jena,
1878, p. 69. r
E. STAHL, Zur Biologie der Myxomyceten (Bot. Ztg. 1884).
The zoological material, which lies on the confines of the domain of the Mycetozoa
.and encroaches upon it, together with a list of works on the subject will be found in the
copious treatise of H. G. Bronn entitled Klassen and Ordnungen des Thierreichs, I,
Protozoa, edited by O. Bütschli, Leipzig and Heidelberg, 1880. The student is specially
referred to this work. ;

Tuirp Part.

BACTERIA OR SCHIZOMYCETES.

CHAPTER X. MORPHOLOGY OF THE BACTERIA.

Section CXXIX. The forms which we have now to consider are termed: by
Nägeli! Schizomycetes or Fission-Fungi; they are known also by an older
name, Bacteria, which was restored by Cohn in 1872 as the designation of the entire
group. I prefer the latter appellation for a group which not only includes Fungi~in
Nägeli’s sense, namely Thallophytes which have no chlorophyll, but has among its
most characteristic members forms which contain chlorophyll and cannot therefore
with any propriety be termed Fungi. I avoid the use of the term Bacterium as a
generic name. To denote the species which constitute the genus Bacterium of
authors, I use partly the generic name Bacillus which will be more precisely de-
fined in the sequel, and partly the name Arthrobacterium, the latter being applied
to all species in which endogenous formation of spores, to be described presently,
has not yet been observed. It must not be supposed that we have in this way effected
a final reform of the nomenclature; we gain only a short expression for the present
state of our still very imperfect knowledge.

The Bacteria consist of minute cells often less than ı a in breadth, and are
either isodiametric or roundish in shape or else cylindrical and rod-like; they
multiply if supplied with a sufficient amount of food by successive bipartitions, each
cell dividing into two similar daughter-cells through an unlimited number of genera-
tions. The successive divisions are in most cases all in the same direction, and hence
all the cells which have proceeded from one initial cell are arranged in a single simple
filiform row if they remain united to one another. All the members of the row are
alike capable of growth and division. It less frequently happens that, without any
other change in the behaviour of the cells, the successive divisions take place in
alternately varying directions, so that the arrangement of the generations which
continue connected together is from the first other than that of a simple row.

Verhandl. d. Deutschen Naturforscher-Versammlung zu Bonn. See Bot. Ztg. 1857, p. 760.

CHAPTER X.—-MORPHOLOGY OF THE BACTERIA. 455

Little is known of the more intimate construction of the cells of the Bacteria,
owing to their minute size. All that can with any confidence be affirmed of the
greater part of them is founded less on direct observation than on the analogy of the
larger cells of other organisms, with which they agree in their chief characteristics so
far as these can be recognised, and with which they are also connected by inter-
mediate forms.

The protoplasm of the cell in most forms and even in the larger ones appears,
when in a state of active vegetation, to be a homogeneous and faintly refringent
mass filling the cell-cavity. Distinct little granules (microsomata), the constitution
of which is still undetermined, may be distinguished occasionally in the larger
forms in this condition. They appear in greater abundance as the vegetative
activity diminishes, and the protoplasm may then be still more frequently seen to form
a parietal layer inclosing a pellucid central cavity. Highly refringent (crystalline)
granules of sulphur, which owe their origin to the decomposition of the sulphates by the
plant, are often imbedded in considerable quantity in the protoplasm of the species of
Beggiatoa which grow in springs containing sulphur, as was first pointed out by
Cramer and Lothar Meyer.

The protoplasm of some species which appear to belong to this group forms:
chlorophyll, and seems to be coloured green throughout by this substance. Van
Tieghem found two forms of this kind living in water, which he distinguishes as
Bacterium (Arthrobacterium) viride and Bacillus virens!; W. Engelmann a third
marked by the very pale tint of its chlorophyll, which he names Bacterium
(Arthrobacterium) chlorinum ?.

Most species are distinguished by the absence of chlorophyli and analogous
colouring-matters. In this respect they agree with the Fungi, and it is owing to this fact
and its physiological consequences that they have received the name of Fungi. In’
some species, Zopf’s Beggiatoa roseo-persicina for example and its subordinate forms,
the protoplasm is uniformly tinged with a red colouring-matter, which Lankester has
carefully examined and named bacteriopurpurin*. It is not yet certainly ascertained
whether the colouring matters, which often give an intensely red, blue, yellow, or
other tint to the gelatinous accumulations of some small forms, such as Micrococcus
prodigiosus, are contained in the membranes only or are attached also to the
protoplasm,

Some species which contain no chlorophyll form a substance in their protoplasm,
which from its behaviour with reagents and the physiological relationships observed in
certain cases, must be considered to be more or less like starch, or more correctly
granulose. The cells of Prazmowski’s Bacillus (Clostridium) butyricus (Amylobacter
Clostridium, Trécul) and Spirillum amyliferum, van Tieghem‘, become more highly
refringent in the stages which precede the formation of spores (section CXXX), and their
protoplasm then assumes a blue or violet colour with solution of iodine, either

1 Bull. Soc. bot. de France, 27 (1880), p. 174. The figure there given by Van Tieghem from -
Perty is interesting, but it must remain a question whether it belongs to this group.

2 Bot. Ztg. 1882, p. 323.

® Quart. Journ. of Micr. Sc., New Series, XIII (1873), p. 408.

* See Prazmowski, Unters. ii. d, Entwickgsg. u. Fermentwirk. einiger Bacterienarten, Leipzig,
1880, and Van Tieghem in Bull. Soc. Bot, de France, XXVI (1879), p. 65.

456 THIRD PART.—BACTERIA OR SCHIZOMYCETES.

throughout or with the exception of certain transverse zones which do not turn blue ; and
in both cases the substance which has become blue spreads uniformly through the
protoplasm, without forming bodies in it of definite shape. This phenomenon has
been observed when the nutrient substratum contains starch, and when it is entirely
free from starch. The amyloid substance disappears with the formation of spores.
This amyloid reaction with iodine occurs in Hansen’s vinegar-forming Arthrobacterium
(Bacterium) Pastorianum, and occasionally in Leptothrix buccalis 1, but without proof
of any connexion with spore-formation ; it is not found in the majority of the forms
which have been examined, nor is there any report of the occurrence of amyloid bodies.
in the species which contain chlorophyll.

Nuclei have not as yet been observed in Bacteria. .

The protoplasm of the Bacteria is surrounded in all cases, so far as we can de-
termine, by a membrane. In the case of cells or cell-rows which vegetate actively
in a fluid as isolated bodies and do not become cemented together into large
masses the cell-wall appears on the lateral faces of the protoplasmic body as a thin
bounding surface; on the boundary lines of cylindrical cells closely united in rows it
is a septum, which is in many cases only to be distinguished by the use of desiccating
and colouring reagents, and is so entirely invisible in the living specimen that a
cell-row composed of several cells looks like a homogeneous unsegmented cylinder.

This delicate membrane immediately clothing the protoplasmic body must, in’
some forms at least, and especially in some species of Spirillum, be highly extensible
and at the same time elastic. The straight cylindrical body in these species is often
seen to bend strongly backwards, and then to recover its former direction. According
to the views which prevail at the present day it is the protoplasm only that can be
supposed to be the active cause in this phenomenon, and the investing membrane
must possess the qualities just mentioned to be able to follow its movements.

Few or more probably no vegetating cells of Bacteria are clothed with this delicate
membrane alone at the highest stage of their. development. This is only the inner-
most lamella of a membrane which .increases in thickness, and in doing so swells
and becomes gelatinous in its outer portions. Such gelatinous outer layers or invest-
ments are found wherever care is taken to observe them, and direct examination
shows that they are either connected in the manner indicated with the delicate inner
membrane or are formed from it.

The particular character of the gelatinous envelope varies in the different species
within wide limits. In the freely moving rod-like cells of the typical Bacteria it is
invisible, but it can be recognised in the flakes of slimy matter formed by larger
accumulations of these forms. In other cases it is of greater thickness and firmer
consistence, and may either form distinct gelatinous sheaths round isolated cells and
aggregates of cells, or unite and cement the cells together into larger gelatinous
masses.

The chemical composition of these gelatinous membranes would appear to be
very different in different species. Löw * found that the membranes of the mother of

! See Zopf, Spaltpilze.
2 Nägeli, Ueber d. chem, Zusammensetzung d. Hefe (Sitzgsber. d. Münchener Acad., Mai, 1871);
—Id., Theorie d. Gahrung, p. 111. .

CHAPTER X.—MORPHOLOGF OF THE BACTERIA. :457

vinegar, and Scheibler and Durin ! that those of Leuconostoc mesenterioides, were
chiefly composed of the carbohydrate which comes nearest to cellulose; but it
appears probable from the researches of Nencki and Schaffer? that in the gelatinous
masses (zoogloeae) of purtrefactive Bacteria it consists chiefly of the albuminoid
compound which is the principal constituent of the protoplasm of the cell, and to
which these writers have given the name of mycoprofein, in combination with
infinitesimal quantities of cellulose-like substance. I speak of this as probable only,
because it is always a little doubtful how far the substances discovered by
macrochemical examination have belonged to the one or the other portion of these
minute bodies.

The membranes are in very many cases colourless; but in some instances, as
has been already said, it is supposed that the intense blue, red, and other hues assumed
by some bacteria-masses, and due to colouring-matters resembling anilin dyes, do
really belong to the gelatinous membranes, provided they are not excretory products
which have found their way into the substratum®. The sheaths round the filament of
Cladothrix and Crenothrix are-often rust-coloured or dark brown from the presence of
ferrous hydrate disseminated through their substance.

Many forms of Bacteria have the free movement of swarm-cells in fluids.
Their rapid forward motion is- accompanied with rotation round their longitudinal
axis, and in many cases with apparent curvature of their bodies, But many observa-
tions under the most favourable circumstances have failed to detect in these forms
anything like a distinct organ of locomotion. There are however other swarming
forms in which extremely delicate filiform processes described as cilia or ‘flagella’
have been observed since Cohn’s, or even perhaps since Ehrenberg’s time; these
processes appear at one or both extremities, one usually but sometimes two or even
three together, proceeding from the same point. It would appear to be uncertain
whether these formations, like the cilia of other vegetable swarm-cells, are parts and
processes of the protoplasm and project through the membrane, or whether they
belong to, and are appendages of the membrane itself. The grounds which Van
Tieghem * alleges for the latter view, namely that no direct connection can be traced
between these processes and the protoplasm of the cell, while they behave towards
colouring reagents in the same way as the membrane and not as the protoplasm, are
against their being true cilia. It is to say the least questionable whether they
function as organs of locomotion, considering the irregularity of their occurrence in
the forms which are endowed with motion; and it would also be well to enquire
whether the so-called flagella or cilia may not vary in character according to the
species, and belong in some instances, as for example in Bacillus subtilis, to the
membrane, in others, as in the larger arthrosporous species, to the protoplasmi.

According to the shapes in which they appease in the vegetative states a series
of principal forms are distinguished :—

+ See Van Tieghem in Ann. d. sc. nat. ser. 6, VII, p. 180.

2 Journ. f. pract. Chemie, neue Folge, 20 (1879), p. 443.

3 See Schröter, Ueber einige durch Bacterien gebildete Pigmente, and Cohn’s Beiträge z. Biol.,
Heft 2, p. 109; also Nägeli, Untersuch. ii. niedere Pilze, p. 20.

* Bull. Soc. Bot. de France, XX VI (1879), p. 37-

458 THIRD PART.—BACTERIA OR SCHIZOMYCETES.

‘a. Regard being had solely to the shape of the isolated cells or to
their simplest genetic union, —

1. Cocci: isolated cells which are isodiametric or at least very slightly elongated
in one direction. These are distinguished. when necessary according to their
dimensions into mzcrococct, macrococct and monad-forms.

2. Rod-like forms: cells elongated in one direction and cylindrical, rarely
fusiform, isolated or in a short chain. These again are distinguished into
short rods (Bacteria), long rods (Bactili), fusiform rods (Clostridia) and some others.

3. Spiral forms: spirally twisted rods, some with narrrow coils (Spirillum,
Sptrochaete), some with distant and very steep coils (Vibriones).

It follows necessarily from what has been already stated that no sharp line of
distinction as regards their shape can be drawn between short rods, for instance, arid
cocci, or between a slightly twisted Vibrio and a Bacillus which departs to a trifling
extent only from a mathematically straight line; nor can they at present be always
clearly distinguished by their structure. .

This is especially the case with respect to the rod-like forms, since a rod may be
a single cell of the corresponding shape, or a number of cells firmly connected together
and closely related to one another genetically. In the latter case while the cell is
dividing repeatedly, the partition-wall may be of so delicate a structure that the com:
pound body, if not carefully examined, may be taken for a simple homogeneous
body. Hence when these organisims are simply spoken of as rods we must under-
stand that the writer is alluding to their outward appearance only, unless the structure
also is exactly described.

To these three kinds must be added a fourth, namely the swollen bladder-like
forms. Individuals of this kind are found in company with the other three and are
evidently produced from them ; they are distinguished by having their cell swollen to
several times the size of the other form, with a knobbed and irregular outline,
These inflated forms have been observed in artificial cultivations where the nutrient
substances are in insufficient quantity or are exhausted; Zopf and Cienkowski found
them in Cladothrix and Crenothrix, Buchner and Prazmowski in forms of Bacillus,
and Neelsen in Bacterium cyanogenum. They are therefore considered to be
diseased states of the other forms, and have been termed by Nägeli and Buchner
involuiton-forms. Hansen, on the other hand, has shown that they occur very
frequently, indeed almost invariably, with the Bacteria of mother of vinegar; we do
not know whether they have not some further meaning in this and perhaps also in
most other cases.

6. According to the mode of the connection between the individual
cells, each of the above form-groups may be,—

I. free, that is not firmly joined together, though occurring in the society of
great numbers of like individuals.

2. in the form of filaments, that is joined together and forming long filiform
rows. These filaments are unbranched in most Schizomycetes and then the form is
known as Lepfothrix or Mycothrix ; they are branched in a few cases only (Cladothrix).
In the latter form one extremity of a cell bends outward from the row in which
it occurs, and continues its growth and divisions in a divergent direction. The

CHAPTER X.—MORPHOLOGY OF THE BACTERIA. 459

terminology adopted in the case of the Scytonemeae is also applied to this form of
branching in the Schizomycetes, which has therefore been designated by the really in-
correct or at least unnecessary name of false branching (pseudo-ramification).

In some of the larger forms of this group, Crenothrix for example, Cladothri‘x,
and species of Beggiatoa, the filaments attach themselves by one extremity to fixed
bodies, while the other extremity stretches free into the surrounding fluid; here
therefore there is a distinction between base and apex, and this is accompanied by
certain corresponding phenomena of growth, such as the direction of the branches
and some others. .

The formation of filaments occurs in those Schizomycetes in which growth and
divisions advance only or chiefly in one, and that the longitudinal direction. If these
take place alternately in two or three directions while the genetic connection is
maintained, then ,

3. Groups of cells are produced forming flat surfaces or masses. The
dice-shaped pockets of Sarcina ventriculi are the best-known examples of this kind.
Figs. 170 x and 175 a will give an idea of their appearance.

4. The isolated and connected forms of each of the kinds described above may
again be united by coherent mucilage into larger gelatinous masses, which are known
by the older and more general name of Palmella, or by the ‘more recent term ‘of
Zoogloea. These masses form gelatinous layers or pellicles according to the
species or culture-form, and cover the surface of the solid or fluid substratum ; or
if suspended in a fluid they form lumpy bodies of very various shapes and are often
lobed and branched. The gelatinous cell-membranes in these masses are either
fused together into a homogeneous structure, or show a Stratification which varies
in the different isolated cells or aggregates of cells. In the larger and more firmly
united masses the cells, whether isolated or connected together, have not the power
of locomotion which many of them, as we have seen, possess in the free state.

All these varieties of shape and connection are merely growth-forms like those
designated Filamentous Fungi, Sprouting Fungi, Compound Fungus-body, &c.
(see section I). But the Bacteria were at first distinguished into species
and genera according to these forms of growth, and on the too hasty assump-
tion that the forms produced from them were always like the parents, and
since the year 1872 these distinctions have been precisely defined by Cohn. But
it is obvious from what has now been stated that we are dealing in the present case
with /orm-species and form-genera only, using these words in the sense assigned
to them on page 120; the names Micrococcus, Bacillus, Spirillum, Spirochaete,
Vibrio, Leptothrix, Zoogloea and others, applied above to the Schizomycetes, were
in this sense used originally as names of genera and not as designations of forms
of growth. The relations of these form-genera to the natural genera, that is to the
genera founded on the entire course of development, will be considered presently.

Section CXXX. The forms comprised under the name of Bacteria or Schizo-
mycetes may be distributed, in accordance with the course of their development.
and with the facts as at present known to us, into two groups, and such is to some
extent the course adopted by Van Tieghem in his new text-book. The first group
will contain the species which have their spores formed endogenously, the Endo-

460 ‚THIRD PART.—BACTERIA OR SCHIZOMYCETES.

sporous Bacteria; the second those which have no endogenous spore-formation, ‘the
Arthrosporous Bacteria. It has yet to be seen whether this distinction will. be
permanently maintained. It is evident from the gaps in our present knowledge
that many forms are met with whose behaviour in this respect has not yet been
ascertained. The distinction therefore is not a convenient one for a purely practical
classification of the Bacteria.

a. ENDOSPOROUS BACTERIA.

The forms included under this term are chiefly known in the growth-form
of single rods consisting of one or a few cells, or of rods joined: together and forming
long filaments; they may also be collected together into larger gelatinous masses
or membranes. In some forms the rods are spirally twisted, and these I name here
Spirillum of Van Tieghem. Others do not show these curvatures, but are either
straight or very slightly bent; all these I include under the term Bacillus and place
under that genus all the endosporous forms which have been hitherto known either
as Bacillus or as Clostridium, Bacteridium, Vibrio, or by some other name. All
non-endosporous forms bearing these names on account of their growth-form are
of course excluded from the group. ;

The Bacteria in question are distinguished by the peculiar mode of spore-
formation. At the commencement of the process the protoplasm of each cell
which has hitherto been homogeneous becomes somewhat darker and in some cases
visibly granular, and in the forms enumerated on page 455, which however are the
smaller number, it gives the amyloid reaction. Then a darker and comparatively
very small body makes its appearance in the interior of each:cell and soon increases
rapidly in volume, acquiring a distinct outline some time before it reaches its ultimate
size and becoming strongly refringent. It has now the aspect of a glistening bluish
sharply defined dark granule, and continues to grow till it has reached its definite
size and shape, which it does in the space of a few hours. As it enlarges, the
surrounding protoplasm or the amyloid substance disappears, and the body when
fully developed is surrounded only by a pellucid substance inside the very delicate
membrane of the mother-cell; this body may be termed a spore or resting spore.

In the great majority of observed cases one spore only is formed each time
in a cell, The supposed exceptional case’ of two spores being formed in a single
cell is rare, and is moreover said to occur in forms which as a rule produce only,
one spore ; it is possible that the partition-wall between two sporogenous cells may
have been overlooked. The sporogenous cell is according to the species either not
different from the vegetating cells of the same species or form, or is distinguished
by being somewhat thicker and of a different shape; the change of shape is often
caused by the appearance of a fusiform or club-shaped enlargement at one extremity,
in which the spore is formed. In this case the mature spore is usually much shorter
than the mother-cell, and is seen as a glistening body in the enlarged portion of the
parent-cell; the apparently empty part of the cell, and in some cases also sterile

‘ Prazmowski, as cited on page 455.—E. Kern, Ueber ein Milchferment &c. (Bot. Ztg. 1882,
p- 264, and Bull. Soc. Hist. Nat. Moscon, 1882),

CHAP. X.—MORPHOLOGY OF THE BACTERIA.—ENDOSPOROUS BACTERIA, 461

cylindrical sister-cells, is attached. to the spore as a longer or -shofter appendage.
Such structures with one swollen sporiferous extremity are the ‘capitate Bacteria’
of older writers. In other species there is less difference in size between the spore
and the mother-cell, though the latter is never quite filled by the spore. - In
Spirillum amyliferum and Bacillus (Clostridium) butyricus, which show the granulose-
reaction before the formation of the spore, the spot where the comparatively small
spore begins and completes its formation is, according to Van Tieghem, a terminal
portion of the mother-cell in which there is no granulose. ’

The motile forms may continue their movement during the development of the
spore; they become stationary as the spore matures, and finally in all cases the
membrane of the mother-cell dissolves sooner or later and the spore is set at
liberty. :

In most of the species which have been examined the formation of spores
coincides with the moment when the substratum has expended its nutrient material
or from other causes, such as an accumulation of products of fermentation, has
become unfitted to support the vegetation of the species. At the same time the
phenomenon does not always depend on the quality of the substratum. Prazmowski
has shown that Bacillus butyricus may be in active process of vegetative multiplication
while some of its cells are forming and maturing their spores.

The formation of spores when once begun extends usually to the greater
number of the isolated cells and aggregates of cells in a pure culture; but a
certain number of the cells remain sterile, and no definite rule determining their
distribution has yet been discovered. The parts which remain sterile are seen to
break up and disappear if. fresh nutriment is not supplied in time; if it is supplied
they may continue to vegetate. Plants grown in quantity in a pure medium and
left to themselves often produce enormous masses Of ripe spores.

The ripe spore varies from round to elongate-ellipsoidal or cylindrical according
to the species. It has the appearance, as has been already said, -of a highly
refringent usually colourless body (reddish in Bacillus erythrosporus, Cohn) with a
dark and sharply defined outline; in some cases it looks like an oil-drop, but
reagents show that the resemblance to the latter is only superficial. It consists of 2
highly refringent mass of protoplasm, which with our present means of’ investigation
is perfectly homogeneous. This protoplasmic body, as is shown in germination,
is closely surrounded. by a thin but firm and often apparently brittle membrane;
outside the cell-wall may often be seen a pale slightly refringent envelope with
lightly marked contour and of apparently gelatinous consistence, the material com-
position of which cannot be exactly ascertained, but which forms a delicate covering
to the spore, and sometimes also appears to be proloriged at each extremity of the
spore into a small tail-like appendage. Pasteur? was the first who described these
appearances but he did not distinctly recognise their significance.

The bodies in question are proved by their germination to be spores. They.
are in a condition to. germinate, as soon as they have reached the development
described above at the expense of the mother-cell; and they retain the power of

1 Etudes sur la maladie des vers a soie, I, 228.

462 THIRD PART.—BACTERIA OR SCHIZOMYCETES.

germination for a considerable time, showing a remarkable depree of resistance to
the effects of desiccation, extreme temperatures and the like (see section CXXXIV)..

Germination commences as soon as the spore is subjected to the conditions
required for the nutrition and vegetation of the species, that is, as soon as it is placed
in a suitable nutrient solution at a proper temperature. It is completed in a few.
hours when the conditions are favourable, and consists chiefly in the development
of the spore into a cell which assumes all the characters of the parent-cell as regards
conformation and vegetation. The spore at first enlarges in size, loses its high
refringent power and becomes pale and turbid, like a bacterium-cell when in an active
state of vegetation; it then elongates and assumes the shape characteristic of the
species and at once begins to divide like the vegetative cell, and locomotion may
commence at the same time. When the elongation has reached a certain small
amount, which is moreover different in different individuals, a membrane dividing
usually into two regular valves of equal size is seen in most cases to separate
gradually from the growing cell, being evidently raised off from it by the hyaline
gelatinous outer layer of the membrane of the growing cell. The valves are usually
thin and pale-coloured; but in Bacillus subtilis they have nearly the same amount
of refringent power as the ripe spore, so that it is probable that the latter owes its
characteristic appearance to the membrane which is thrown off in germination. The
pieces of the detached membrane gradually disappear in the surrounding fluid. In
spores which have elongated in the direction of the longitudinal axis of the mother-
cell the membrane splits in the same or in the transverse direction. The direction.
varies with the species; the membrane for example of Bacillus butyricus according
to Prazmowski, and of other species, parts longitudinally, that of Bacillus subtilis
transversely.

The membrane. is not thrown off in the above manner in all cases in germi-
nation, but is sometimes seen to swell up and finally disappear. I observed this
repeatedly in Bacillus Megaterium and Buchner? saw it in the Bacillus of anthrax.

The direction of growth in length of the vegetative cell first developed from
the spore in relation to the longitudinal axis of the spore or its mother-cell is the
same in all observed cases as that of the spore, whether the spore-membrane bursts
longitudinally or transversely, or swells up and disappears. This is the case also
with Bacillus subtilis, as will be described hereafter at greater length, where according
to Brefeld and Prazmowski the first cell usually issues transversely at right angles
to the longitudinal axis of the spore from the spore-membrane which has burst
on one side.

The above is the course of development observed especially by Brefeld, Van
Tieghem? and Prazmowski in many of the species which contain no chlorophyll. It
occurs also in. Van Tieghem’s species containing chlorophyll which have been
mentioned above. In these the chlorophyll disappears during the formation of the
spores and reappears in germination. Whether the bacterium of blue milk is one
of this kind is still uncertain after Neelsen’s account? of it and requires further
investigation.

1 Nägeli, p. 272. * See Van Tieghem in Bull. Soc. Bot. 26 (1879), p. 141.
3 Cohn’s Beitr. III, Heft 2.

CHAP. X.—MORPHOLOGY OF THE BACTERIA.—ENDOSPOROUS BACTERIA, 463

All the above phenomena are in themselves sufficiently simple, and ‘their
course is essentially the same in all the species; but it is nevertheless desirable
that we should study a few examples more closely, and see in what light the
parts in question present themselves and the form which the specific differences
assume.

Our first example shall be the large species long known in our laboratories by
the name of Bacillus Megaterium. This exceedingly instructive form (see Fig. 194)
was first observed in boiled cabbage-leaves used for the cultivation of Myxomycetes
and species of moulds, and was afterwards studied in pure cultures in water or gelatine
mixed with 7-10 per cent. of grape sugar and a small quantity of meat-extract and
also in a pure 2-3 per cent. solution of
meat-extract. The gelatine is liquefied by

the Bacillus. Most of the cultures to be a?
described below were carried out in the Sy
summer-temperature of an ordinary room, =
that is, not much above or below 20° C. 2

This species forms small rods 2-5 p»
in thickness and cylindrical in shape with
the ends rounded off. The rods, which
do best when obtained from spores, grow
rapidly in a fresh nutrient solution where
they have no competitors to disturb them,
and become usually 4-6 times longer than
they are broad; then they separate by trans-
verse division into two halves or into two

FIG. 194. Bacillus Megaterium. a outline of a motile
chain of rods in active vegetation. 4 a pair of motile rods in
active v i pa i rod in the state of 5
after treatment with alcoholic solution of iodine. c a five-

unequal parts, which again grow to rods of
the size above mentioned (Fig. 194 a, 4).
A single rod floating in the solution usually
appears in these circumstances even under
high magnifying power to be unsegmented,
and to be filled with a slightly refringent
protoplasm in which only a few separate
granules can be distinguished. But the
application of desiccating and colouring re-
agents, alcohol and tincture of iodine for
example, shows that the rods even in this

celled rod in the first preparation for forming spores. d-f
successive stages of a pair of rods while forming spores, ¢
about two o'clock in the afternoon, ¢ about one hour later,
Jan hour later thane. The spores in formation in /are ripe
towards evening; no others were formed, the one which .
apparently began to be formed in the third cell from the top
in d and e has disappeared ; the cells in / which did not con- -
tain spores perished by about nine o’clock in the evening.
r a quadricellular rod with ripe spores. gl a five.celled :
rod with three ripe spores placed in a nutrient solution
after several days’ desiccation, half-an-hour after noon.
g? the same specimen at about half-past one. g3the same
about four o'clock. 4, two spores with the walls of the mo- ‘
ther-cells dried and then placed in a nutrient solution about
forty-five minutes after eleven. 42 the same about half- |
past twelve. z, 4, / later stages of germination as explained
inthetext. “arod formed from a spore placed eight hours"
before in a nutrient fluid and in the act of splitting trans-
versely. a@ magn. 250, the rest of the figures 600.times.

state consist of short members which become twice. as long as broad or a
little longer, and then divide by the formation of a transverse septum into two
members (2). The transverse septa are extremely delicate when young, but when
the water is withdrawn by a reagent they and the lateral wall stand out clearly
distinguished from the shrunken protoplasm. Older transverse septa swell to a
greater thickness in the living individual, and acquire at the same time a soft
gelatinous consistence; this causes the transverse splitting of the longer rods men-
tioned above, the pieces remaining loosely coherent or separating entirely from one
another, according to the relation between the cohesion of the jelly and the . forces
from without which promote a separation. ’

464 THIRD PART.—BACTERIA OR SCHIZOMYCETES.

The rods are usually not quite straight but slightly curved. The curvature
often appeared to me to change from one direction to another in the same individual,
but it was impossible to feel sure of this point in presence of other movements to be
described presently. When two sister-rods begin to separate transversely from one
another, the curvature usually becomes somewhat more pronounced at the extremities
where the division takes place, and the ends of the rods become slightly oblique to
one another and overlap each other a little, or one thrusts itself laterally past the
other, like the short commencement of a so-called false branch in Scytonema and
similar genera of the Nostocaceae (Fig. 194 4, m). In these conformations the rods
may either separate from one another in rapid succession, or remain united but
always loosely united by their extremities into chains of varying numbers of members,
seldom more than ten (Fig. 134 @). It follows from what has been already said, that
a chain of this description is never quite straight; its general outline, when it is sup-
posed to be at rest, is different in individual cases ; it is irregularly undulated, and kneed
where the members join one another, often forming more or less acute angles, and
never approaches the form of a regular spiral. But in the stage of development of
which we are now speaking the chain of rods is never in a state of rest; the rods
are ink. constant though comparatively slow movement. There is first a movement of
rotation,.each.rod rotating about its longitudinal axis. Secondly there is a swinging:
movement; one or both extremities of the rod describes a nearly circular path in
suchia manner, that in the first case the outer surface of the rod moves in the path
of the side of a cone the apex of which is formed by the other extremity of the rod;
in the second case it moves in the path of the sides Of two cones the apices of which
meet in the middle of the rod after the fashion of an hour-glass. Thirdly, there is a
movement of progression, the rod moving through the fluid in varying and still undeter-
mined directions. If the rods are united together into a chain, all the cells move
together through the fluid in the same direction, but each separate rod shows the
tendency to the rotation and swinging mentioned above. These movements are
disturbed or prevented in proportion to the resistance encountered from the cohesion
of the gelatinous substance which binds the cells together, and from the mass and
movement of the cohering cells. Hence chains formed of ‚several members move
forward in irregularly varying directions and with not less irregularly varying
undulations, and with varying degrees of articulate movement at the points of
junction. Vibratile cilia or flagella have never been observed in this species.

If a pure culture is obtained on a microscopic slide from the smallest possible
number of spores, the Bacillus will be found in 24-28 hours to have multiplied to such
a degree, that the nutrient fluid, which at first was perfectly clear to the naked eye,
has become turbid and milky; the organisms themselves are diffused with tolerable
uniformity through the fluid, or some of them are settling to the bottom. Most but
not all of the little rods now separate from one another, and each consists of about
4-6 isodiametric cells. The transverse walls between the cells, though always
delicate, become gradually more defined. The protoplasm fills the cell-cavity less
perfectly, and appears to line the wall of the cell and to inclose a clearer central
space; it is also dotted with a number of granules, some of which are highly refrin-
gent (Fig. 194 ¢, d). In this stage the cells have ceased to increase in size and to
divide, and are preparing to form spores. The commencement of the formation of a

CHAP, X.—MORPHOLOGY OF THE BACTERIA.—ENDOSPOROUS BACTERIA, 465

spore in a cell is indicated by the apppearance of a small roundish highly refringent
body in the protoplasm, usually close to the surface of one extremity of the cell. The
nature of this body cannot be clearly made out, but the first impression which it
conveys is the same as if one of the highly refringent bodies just mentioned as
disseminated through the protoplasm had increased somewhat in size. The body
then grows perceptibly larger while the protoplasm round it diminishes (Fig. 194
d,e,f). In the course of a few hours it grows into a longish cylindrical object, which
is shown by its subsequent behaviour to be a spore. The spore is slightly shorter than
the cell which produces it, but its breadth is only from a third to one half of it. It
has a sharply defined outline, appears to be perfectly homogeneous, is very highly re-
fringent, and has a bluish tint. This is the appearance which it presents long before it
attains to its full size. As it grows, the protoplasm which surrounds it becomes con-
tinually clearer and more transparent ; when full-grown it lies straight or oblique in a
pellucid substance within the membrane of the mother-cell, which is persistent for a
time, but which if kept in the fluid at length disappears entirely and leaves the spore at
liberty. Only one spore is ever formed in each cell. It is remarkable how often the
formation of spores begins in the terminal cells of a rod, though this is not always the
case, and proceeds rapidly from them to the adjacent cells. It takes place not
unfrequently in all the cells of a rod, and always in the majority of them in
successful cultures ; but single cells often prove an exception to this rule, and spores
sometimes begin to form in a cell but are never fully developed. In all these cases
the cells which do not produce'spores die off unless a timely supply of fresh nutriment
excites some of them to renewed vegetation.

The movement of the rods becomes slower perhaps when spores begin to be
formed, but does not at once cease, and this is highly inconvenient for those who are
watching the process of spore-formation. It is only when all the cells of a rod have
formed spores, or those which produce no spores are dead, that the rods lose the
power of motion.

The germination of the spores (Fig. 194 g-m) has been observed in material
kept dry for at least 24 hours after maturation. If material in this state is placed in
a fresh nutrient solution, the cells in which no spores have formed cease to grow, and
drop off one by one. The membranes of some of the sporiferous cells may have burst
before desiccation, otherwise they still remain round the ripe spore; in the latter
case they are now seen to swell up gradually and dissolve, so that the spores are
released from the previous combination. At the same time the dark outline and the
high refringent power of the spore itself disappear, and it assumes the uniformly pale
aspect of a rod when actively vegetating, having its outline, especially at the
extremities, at most only a little more distinctly defined than in the rest of its
body. In this condition it increases slowly in volume during several hours (8-12
in the observed cultures) till it has become as broad as a normal rod without
essentially deviating from its original shape. Then not unfrequently a thin
membrane divides transversely or obliquely into two portions and is all at
once separated from its surface, and the delicately circumscribed cell slips out,
having the breadth, shape and structure of a short rod, and then grows rapidly
in the direction of its previous longer axis and commences the active vegetation

described above.
[4] Hh

466 THIRD PART.—-BACTERIA OR SCHIZOMFCETES.

The removal of the transversely-opened membrane is the best and only certain
demonstration of the fact that the spore is actually invested with a special membrane.
This membrane is easy of observation, especially in cultures in very flat drops of the
fluid. It sometimes divides quite across into two halves, which are attached at first
like caps to the extremities of the elongating rod and are afterwards torn from them.
I often failed to observe the final removal of the membrane in larger quantities of the
fluid. There each cap, distinguished by. its more
sharply defined outline, was seen to be attached to
the extremities of the growing spore and gradually
ceased to be distinguishable ; it would seem therefore
that in these cases the membrane, after splitting trans-
versely, is not removed from the spore in connected
pieces, but swells up or is dissolved and so disappears.
The membrane often clings to the rod-cell which has
slipped out of it in such a manner that the longer
diameters of the two bodies cross one another, and
hence the appearance is produced as ‘if the growth
in length in germination is in a direction at right
angles to the longer diameter of the spore or parent-
rod; but this is not really the case.

The species which we are considering occurs
also in another form, namely in long curved chains,
in which a segmentation of the smooth cylindrical
rods is only obscurely distinguishable, while the
isodiametric cells on the other hand are distinctly
defined, are slightly swollen and protuberant, and are

Fic. 195. A Bactllus Anthracis.
Two filaments grown on a microscopic
slide in a solution of meat-extract, partly
in an advanced state of spore-formation ;
at the top two ripe spores which have
escaped. The spores are drawn some-
what too narrow; they are nearly as
broad as the transverse diameter of the
mother-cel. B Bacıllus subtilis. 1.
fragments ofa filament with ripe spores.
2. spore beginning to germinate; the
outer wall ruptured transversely. 3.
young rod projecting from the wall of
the Spore in the usual transverse
position. 4. Germ-rods curved in a
horse-shoe shape and with the extremi-
ties connected; one of them with one

Germ-tubes with the two extremities re-
maining connected and already greatly
increased in size. Magn. 600 times,

in many cases themselves curved at the points of
greatest curvature. Torulose chains of this kind or,
to use the terminology noticed above and founded on
growth, coccz grouped in rows, are usually developed
in great abundance, being loosely intertwined into
thick convoluted masses and sometimes breaking up
here and there into separate cells. They are motionless
or show a very slight movement. There was little
or no formation of spores. I almost invariably dis-
covered this form when the cultures were rendered
impure by other small Bacterium-forms, but the

Bacillus formed the majority. It may be a question
how far this fact points to the cause of the appearance of the torulose chains,
but it is certain that they become transformed into the even rods when the culture
is pure.

The cells of the Bacillus of anthrax, B. Anthracis, Cohn (Fig. 195 A), ap-
proach 1 p in thickness in vigorous specimens grown in the blood of animals attacked
by it, and grow to about 3-4 times that length. They are connected together in the
blood into straight rods of different lengths; in cultures on some suitable dead sub-
stance they[form long pluricellular filaments; these may be much twisted or bent into

CHAP, X.~--MORPHOLOGY OF THE BACTERIA.-—ENDOSPOROUS BACTERIA. 467

acute angles, and are at the same time often collected together in great numbers into
bundles or sheaves and coiled round one another; such formations appear as flaky
precipitates in larger quantities of fluid. The mode of spore-formation in the filaments
is the same as in the preceding species. The ripe spores are as broad as the mother-
cells but much shorter, and roundish to ellipsoidal in outline; they are usually set at
liberty soon after reaching maturity by the disorganisation of the membrane of the
mother-cell. They behave in germination like the spores of the preceding species, '
with the difference only that they have not been observed to part with an empty
membrane; I have at most seen a form of cap on the extremities of the spore,
Fig. 194 z, and sometimes it seemed as if a small delicate cap was at length removed
from them.

In some cultures, as for example in solutions of peptone, I have seen the filaments
of this Bacillus break up over a wide area into round cells, cocci, which collect together
into groups forming lumps or clusters. These with some doubtful exceptions were
found to be dead. When removed into a good fresh nutrient solution they showed no
signs of growth but gradually perished, while a few initials gave rise to a new and
luxuriant growth of filaments; but it remained uncertain whether these initials
came from coccus-cells which had retained their vitality, or from spores present in the
solution.

According to the statements of the pathologists’, which however require
morphological proof, the Bacillus of anthrax introduced into an animal appears
to vegetate there during its first period of growth, and during the first stages of the
disease as shown by the fever-temperature, in the form of small round isolated
cells or cocci; after some time it developes into the elongated rods which fill the
blood-passages in the last stage of the disease. I did not find this statement con-
firmed by my experiments with guinea-pigs ; in 20 hours after the introduction of
spores into the skin I found an abundant growth of rods in the blood-vessels near
the point of inoculation.

This Bacillus shows no power of independent movement in any stage of its
development apart from the slight oscillatory motions of doubtful origin which have
been frequently observed during the first stages of germination.

Bacillus subtilis (Fig. 195 2), known as the hay-bacillus from being commonly
obtained from an infusion of hay, behaves much in the same manner as B. Anthracis
when forming its spores; but its filaments are as a rule narrower, and when grown
in largish quantities of fluid they are closely compacted together into a soft gelatinous
pellicle covering the surface o{the fluid while its own upper surface is dry. If the
plant grows vigorously in a comparatively narrow vessel, the surface of the pellicle
becomes wrinkled and folded in consequence of the opposition offered to its surface-
growth by the wall of the vessel.

The formation of spores is exactly the same as in B. Anthracis; the ripe spore
with the zone of the mother-cell which surrounds it is often somewhat broader than
the cell was originally.

It has been shown by Brefeld after a skilful examination of this species, that the
outer wall of the spore, which is comparatively thick and continues to be highly

1 See Roloff in Archiv f. Thierheilkunde, IX, Heft 6 (1883), p. 459.
Hh 2

468 THIRD PART.—BACTERIA OR SCHIZOMYCETES.

refringent, splits across the middle in germination after its first distension into two
portions, which however remain firmly united at one side. The protoplasm invested
with a delicate membrane elongates in the direction of the longer axis of the spore
and of the longer axis of the mother-cell which coincides with it, and at the same time
usually bends through about 90°, and one extremity is thus thrust out of the opening in
the outer wall of the spore while the other extremity remains in the spore. The
“protoplasmic body then developes into a rod. It appears from these phenomena as if
the direction of longitudinal growth in this case in germination is at right angles to
that of the parent-filament, but this is not really so. The wall of the spore which has
opened on one side is evidently very elastic; it manifests so considerable a resistance
to the elongating rod as it bends, that the rod with both its extremities fixed in the
spore becomes curved before the one extremity is set free. The resistance sometimes
goes so far that both extremities remain in the spore, and in that case the elongating
rod assumes the form of a horse-shoe, the limbs of which may be of considerable
length. In other respects its growth is entirely the same as the ordinary growth which
begins with the formation of a bend in the protoplasm, and if the rod subsequently
divides into partial rods, two separate rods answering to the two limbs of the horse-
shoe may often be seen to project side by side from the ruptured wall of the spore
(Fig. 105 B, 4, 8).

The cells produced in germination grow and divide by the formation of transverse
walls ; the products of this growth do not however remain united in a filament, but
separate one after another into rods consisting of a few or in many cases of a single
cylindrical cell, which may be 4-5 times longer than broad. These rods, which multi-
ply very rapidly and abundantly in fluids containing a good supply of food, display
active swarming movements all the time of the kind described above. I was unable to
satisfy myself with regard to the presence of cilia or flagella during the swarming stage
even in Bacillus subtilis. ‘The rods become disseminated through the fluid as they
swarm and render it turbid. The last stage of vegetation is indicated by the entrance
into a state of rest, in which the cells increasing greatly in size remain united
together in filaments and the filaments form pellicles, till at last formation of spores
begins afresh.

6. ARTHROSPOROUS BACTERIA.

Section CXXXI In the course of the development of the species in this group
single members may simply separate from their connection with others, and under
suitable conditions become the initial members of new combinations; they may there-
fore claim to be called spores. In other respects there is no general characteristic
distinction between them and the purely vegetative members.

In connection with the fact ‘that the species in this group are less like one another
than the Endosporous Bacteria, and that some species have a greater variety of
growth-forms, the mode of formation of the cells which may be termed spores varies
greatly in the different species.

It is to the forms of this group that I give the name Arthrobacterium proposed
for them in my introduction on page 454; they resemble Bacillus in their vegetative
form, and are usually known as species of Bacterium, but require a more exact.

CH. X.—MORPHOLOGY OF THE BACTERIA.—ARTHROSPOROUS BACTERIA, 469

morphological investigation. The other genera are distinguished by the difference in
their conformation.

Leuconostoc mesenterioides, the ‘ frog-spawn’ of sugar-factories, consists in the
vegetative state of coiled rosary-like chains of small round cells inclosed in firm sheaths
of mucilage, and accumulated in great numbers into large compact gelatinous masses
(‘zoogloeae’). Many of the cells perish at the close of the vegetative season when the
nutrient substratum is exhausted. Single cells of the rows, disposed at irregular
intervals, become somewhat longer than the rest and have a thicker wall, and their
contents are apparently denser and more highly refringent. They are at length set at
liberty by the dissolution of the mucilage, and they develope in a fresh nutrient
solution into new rosary-like chains resembling the parents.

Arthrobacterium (Bacterium) Zopfii is the name given by Kurth to a species
which was originally found in the intestinal canal of fowls,'and which vegetates at first
in the form of small rods when placed on a fresh nutrient substance. If the
substratum is solid, gelatine for instance with meat-extract, the rods remain connected
together and form long filaments, often with intercalary spiral coils and knots; in a
fluid substratum short resting filaments are formed at high temperatures only, and at
20° C. the rods separate and swarm. When the nutrient substratum is exhausted the
filaments and rods break up into isodiametric members, cocci, which do not them-
selves divide again, resist unfavourable external agencies, and develope into rods or
filaments if supplied with fresh nutriment; they may therefore be termed spores.

A similar course of development is described by Zopf in the case of Arthro-
bacterium (Bacterium) merismopoedioides, a species which vegetates in muddy
water; it is complicated however by the circumstance that the isodiametric cocci which
are the product of the disruption of the rods do not pass into a state of rest, but after
swarming for a time lie without motion on the surface of the water; then they divide
first in one and then in two directions which cross one another alternately at right
angles, and arrange themselves in flat tabular gelatinous expansions in a manner
corresponding to the divisions. If the cocci are now placed in a fresh portion of
muddy water they will again develope, after swarming for a brief time, into rods or
filaments.

Crenothrix, Cladothrix and Beggiatoa are closely comparable in their develop-
ment with the preceding species, but they appear to exhibit a greater variety of
growth-forms. The agreement consists in the copious and uniform multiplication of
the coccus-form, which is alternately aggregated into zoogloeae or is free and even
motile; the cocci are the product of filaments and rods and may develope into them
again. The greater complication of the cycle of forms is due to the assumption by
portions of the filaments and rods of the form of motile spirilla, and to their multiplying
abundantly in thisform. The return from the spiral to the straight forms has, as far as
I know, never been observed. The following brief description from Zopf may assist
in the understanding of these species.

Crenothrix Kühniana (Fig. 196) isa Schizomycete which occurs frequently in
water containing some amount of organic substances, and sometimes in quantities
which are dangerous to health. Its cocci a are spherical in shape and 1-6 « in size.
They multiply by successive bipartitions and in so doing are united into zoogloeae
(A 8), which grow from microscopic minuteness to more than a centimetre in size and

470 THIRD PART.—BACTERIA OR SCHIZOMYCETES.

become aggregated in the water into slimy masses a foot in depth. The gelatinous
matter is at first colourless, but may assume a colour varying from brick-red to dark
brown by admixture of hydrated oxide of iron. When grown in bog-water the cocci
develope into rods or filaments (4) of unequal thickness, which at a certain age become
invested with a continuous thin but firm gelatinous sheath with the same admixture of

iron as is found in the
jelly of the zoogloea-forms.
The single rod-like cells
within their sheaths pass
by repeated transverse bi-
partitions into the form of

& nearly isodiametric mem-

e 9 bers, which then round

a themselves off. The mem-

| bers in the thicker filaments

ei =| often assume a flat disk-like

A Fl on |} shape, and then divide into

N N ’n = | FJ 2-4 small cells by walls

\ SQ | & i parallel to the longitudinal

a mA W lH axis of the filament. Both

3 \, H ® = 7 °Ps these cells and the rounded

f \ A ® = fa) members of the slenderer

9 f Mook 8 H filaments ultimately escape
AA U 2 = j : q

\a ‘| \ <, 4 m j in the form of cocci from

INN BO ‚dei H fp the sheath, being set free

re; H f partly by the swelling of

We the sheath along its whole

length, partly by its rupture
at the apex (7). In the
latter case some of the cocci
slip of themselves out of the
opening in the sheath, while
others are passively thrust
out of it by the growth in
length of the other parts
which remain in the sheath.
The cocci may, though they

FIG. 196, Crenothrix Kühniana. a—¢cceci

orspores. e—ecoecidiyjding. /cocci rarely do, become motile,
collected into a group and d ‘h ya ib "zoo- a :
gloea’),the contour dark. % agroup of cocci developing into filaments, —rfilaments and pass again out of this
of various forms and stoutness hed below to a sub ; m—r show the for-

mation of the common sheath round the single members; ¢ and nm separating above

state into the resting zoo-
into members; » with the upper ly broader and com-
ively shorter, the upp bers having d by longitudinal divisions

a vin gloea-form; they also de-
into round spores (‘cacci’), which have escaped at the upperjend from the sheath. h
£ cocci-zoogloeae. After Zopf. gnatural size, the rest magn. 600 times. velope once more into rods

and filaments in the manner
which has already been described. In addition to these forms curved spirilla-like

forms are also found, which may also break up into pieces, but without passing, as
far as has been at present observed, into the motile state.

CH. X.—MORPHOLOGY OF THE BACTERIA.—ARTHROSPOROUS BACTERIA. 471

Beggiatoa alba (Figs. 197,198) forms filaments which in an intact state are attached
in an erect position to fixed objects in dirty water, in water discharged from factories,
andin hotsulphursprings.
The filaments vary in
thickness from 1 to more
than 5 a, and consist of
a single row of cells, the
protoplasm of which con-
tains granules of sulphur
in quantities differing in
each cell (see page 455) ;
when the sulphur is very
abundant it may be diffi-
cult to perceive the boun-
daries between the cells.
The filaments have no
separate common sheath
and readily divide trans-
versely into pieces. Their
cells pass successively
from the lengthened rod-
form into the isodiametric
form, and these in the
case of the thicker fila-
mentsinto flat discs which
finally divide by longitu-
dinal walls into four quad-
rants (Fig. 127, 6-8).
The disc-like cells as
well as the isodiametric
members of the slender
filaments separate after
a time from one another
(Fig. 197, 9) and round
themselves off, and then
become active swarm-
cells (Fig. 197, 10); at

FIG. 197. Beggiatoa alba. 1 group of 2-5 of
length they come to rest of different stoutness, 5 in the act of breaking up into fragments. The small dark circles in

the interior are granules of sulphur ; in the parts of the filaments where the granules are
and attach themselves to ern in sulphur ;h g the ponds ee Bar
fixed objects. Theymul- Frans ii, 2 aid drin ae dem ere aber
tiply abundantly by bi- > era 2 en A = in all cases granules of sulphur. After Zopf.

partition and form irregu-

larly-shaped zoogloea-heaps. They may also develope into rods and these again
into the filaments above described after the rods have in many cases themselves
passed through the swarming-state. In this species also spirally twisted filaments
are found as well as the straight ones which we have been hitherto considering,

472 THIRD PART.—BACTERIA OR SCHIZOMYCETES.

and these break up into fragments containing from two to several coils and
exhibiting active movement; they were formerly known by the name of Ophidomonas,
and are said to have a long oscillating cilium at each extremity (Fig. 198 £).

The same states have been observed in Beggiatoa roseo-persicina as in B.
alba; the net-like zoogloea-form, once known as Clathrocystis, is a peculiar and
remarkable feature in this species.

Cladothrix and Leptothrix buccalis of tooth-caries resemble each other in
their development. Further details
will be found in Zopf’s descriptions.
The Fungi of mother of vinegar,
Arthrobacterium aceti and A.
Pastorianum (Hansen), must also
be placed in the arthrosporous group.
They are distinguished it is true, as
Hansen has observed, by the occur-
rence of many large vesicular cells
between the small cocci or rod-cells
of a chain, and the almost constant
appearance of these cells at once
suggests that they are connected with
some process of spore-formation.
But the observations afford no distinct
support to this view, and the phe-
nomenon must for the present be
classed with those of involution
which were mentioned on a former
page. The Micrococcus also of
Pasteur’s fowl-cholera may also be-
long to this group}.

Section CXXXII. The fore-
going review of the Bacteria will
supply us with some safe means of
determining the question of the

FIG. 198. Beggratoa alba. Curved and spiral forms. 4 group of specific value of observed. forms,
attached filaments. 3—H portions of spiral filaments; C, D, F—H in a question which is at pr esent th e

the act of dividing into smaller fr and without movement; 7

(Spiros )Peitha ciumar each end, The suiphurgranuleshere asin SUDJect Of much discussion and which
Fig. 197. After Zopf. Magn. 540 times. must not therefore be ignored in
this place.

There are two views on this subject which appear at least to be diametrically
opposed to one another. One of these is, as it seems to me, incorrectly ascribed to
Cohn, and maintains that every Bacterium which occurs in the same growth-form
and produces the same effects of decomposition, though this latter point does not

strictly fall within our limits, represents a species in the sense in which the word

1 Pasteur in Comptes rendus, 90 (1880), pp. 239, 952, 1030, and 92 (1881), p. 430.

CH. X.—MORPHOLOGY OF THE BACTERIA.—ARTHROSPOROUS BACTERIA. 473

is used in natural history. The fact is that Cohn in his publication of the year 1872,
which laid the foundation for the morphological treatment of the group, distinguished
a certain number of genera, Micrococcus, Bacterium, Bacillus, Vibrio, Spirillum, &c.,
by a series of marks, and especially by the shape of the individual cells and their
simplest forms of connection, and gave the name of species to the several forms
which recur regularly within each of these genera, and have a characteristic shape,
decomposing effect and other qualities. It appears therefore that what Cohn dis-
tinguishes is that which we have named above form-genera and form-species.

The other view goes so far in the opposite direction as to deny the existence of
distinct species of Bacteria, and to regard their forms as modifications of one species,
or, as it may be expressed in other terms, it supposes that they are modifications
which may be transformed into one another by breeding. Earlier allusions to this
view are to be found, but it was distinctly opposed to Cohn’s classification by
Lankester + and Lister in 1873 %, and Billroth in 1874 included all forms of Schizo-
mycetes with which he was acquainted in one collective species Coccobacteria septica.
It subsequently received support from the views which Nägeli expressed in 1877
in the words, ‘I have in the last ten years examined some thousands of Schizo-
mycetes and I could not maintain, except in the case of Sarcina, that there is any
necessity for distinguishing them into so many as two specific forms*;’ he adds
however, that he ıs far from asserting that all the forms do belong to a single species, and
that tt would be rash to express a decided opinion in a malter in which morphological
observation and physiological examination are both so defective. He gave utter-
ance to similar sentiments in 1882*, He accepts in fact the principle which led
Cohn to establish his form-genera and form-species and the species which he founded
on physiological characters, namely the necessity for a provisional arrangement, whilst
expressly declining to say whether the forms as distinguished by him do actually
correspond to real natural history species.

Nägeli’s words quoted above in full contain a pregnant criticism of the whole
point in dispute as far as it has at present been explained. Neither side rests on the
only sure foundation, an exact observation of the continuity or non-continuity of the
development of the supposed forms or species, and this is especially apparent in
Billroth’s work. Without this observation the question cannot be decided; it is
more necessary in this case because the forms in question are small and very like one
another, and are often mixed up together and liable therefore, unless very carefully
observed, to be mistaken one for another. Lankester made some approach to an
exact observation of continuity in one case only, in which the characteristic tints of
his Bacterium rubescens (Beggiatoa roseo-persicina) showed the connection between
the forms with more than usual distinctness. We have before us at present some

1 [Professor Ray Lankester in a letter published in Nature, vol. xxxiii. p. 414 (March 4, 1886),
pointing out the significance of his observations upon Bacterium rubescens published in 1873 in
relation to the pleomorphism of Bacteria and criticising the statement in the text, says, ‘ I cannot
think that he [De Bary] gives a correct statement of my relation to the conclusion which he finally
adopts. The view which I put forward in 1873 is precisely that which Professor De Bary now
espouses.’ For further particulars the reader is referred to Professor Ray Lankester’s letter. ]

? Both in the Q. J. Micr. Sc., new series, XIII. 3 Die niederen Pilze &c., p. 20.

* Unters. ü. niedere Pilze, p. 130.

474 THIRD PART.— BACTERIA OR SCHIZOMYCETES.

exact investigations into the morphology and life-history of these plants. It results
from these investigations that the forms above described as cocci, rods, filaments, are
growth-forms, like a tree or shrub, a Filamentous Fungus, Sprouting Fungus or
Fungus-body. It has been shown by Cienkowski, Neelsen, Hansen and Zopf, that
there are species which can assume the different growth-forms one after another,
sometimes with astonishing rapidity. R. Koch, Brefeld, Prazmowski, and Van
Tieghem, have made us acquainted with other species with greater uniformity of
growth, and Buchner has shown that external causes give rise to variations in the
same growth-form in one or more of these species. These investigations all confirm
the view advanced by Cohn, that there are species of Bacteria corresponding to the
species of higher organisms, but the distinctions between them are not those of
Cohn’s form-species. There are comparatively wnzform species, though they may be
capable of some variation, such as Bacillus subtilis, B. Anthracis and B. Megaterium ;
on the other hand there are p/eomorphous species, especially among the arthrosporous
Bacteria, which may appear first in one and then in other quite different growth-
forms. It may be assumed in cases of variation and great differences of form, that
external causes operate to determine the form, and that the growth-form may be the
result of an adaptation to varying external agencies, as happens in cases like that of
Mucor (see page 154), though the operation of these external form-determining
causes has not yet been demonstrated in all cases. In connection with this point it
may be considered probable, that the vegetative process of the different growth-forms
of a species may cause different results of decomposition in the substratum, and that
the decomposing effects of the same form may vary with the substratum. It is with
due attention to these considerations that the determination of the species of the Bac-
teria must now proceed, we may almost say, begin; it is obvious that this must rest
essentially on the morphology of the organisms, while at the same time the physiological
relationships must not be disregarded in the course of the investigation.

Section CXXXIII. As regards the place of the Schizomycetes in the
natural system, it is apparent from the foregoing statements that the course of their
development does not point to any close affinity with the Fungi. To say that they
are offshoots of the Fungi is to ‘contradict all trustworthy observations’? so flatly,
that the view need not be seriously discussed in this place. They are termed Fungi
only in the sense of their being Thallophytes which contain no chlorophyll, and
with reference only to the vegetative process implied by the absence of chlorophyll,
while the course of their development and their classification are entirely disregarded.
The species of Bacillus and Spirillum therefore which have been mentioned above as
containing chlorophyll are at all events no Fungi.

The forms included above under the name of Arthrosporous Schizomycetes
show an unmistakeably close affinity with the chlorophyllaceous and phycochromaceous
Algae, which form the group of Nostocaceae in the wider use of the term as including
the Nostocaceae and Chroococcaceae. This has been generally allowed since Cohn
drew attention to the point in 1853, and it has been recently and very fully worked
out by Zopf. According to our present knowledge the Arthrosporous Bacteria are

1 See Cohn, Beitr. II, p. 188.

CH, X.—MORPHOLOGY OF THE BACTERIA.—ARTHROSPOROUS BACTERIA. 475

simply Nostocaceae or Schizophyta which contain no chlorophyll; at the same time
the position of the entire group in the general system remains still undetermined’.

Of the forms which are here termed Endosporous Bacteria it can only be said at
present that they come nearest of all known forms to the Arthrosporous Bacteria, and
apparently are very nearly allied to them. It may be repeated in this place that the
sharp separation between the two groups rests on the knowledge of them which we at
present possess, and may disappear with its extension. Till then the separation must
be maintained, and it must remain an open question whether the resemblance between
the two groups really implies close affinity, or whether the endosporous forms may not
stand in still nearer relationship to other members of the system. If we look around
us under the guidance of ascertained facts for such affinities, we are led once more,
as Biitschli has also pointed out?, to the Flagellatae. The arthrosporous form
such as Beggiatoa, with their generations alternating between a state of rest and one
of swarming movement by aid of cilia, show an unmistakeable resemblance to the
simpler forms of that varied group. The mode, of forming their spores which is
characteristic of the Endosporous Bacteria finds its analogue, as far as we can
venture to speak in the present state of our knowledge, only in the formation of the
spores or cysts, to use the customary phrase, in the simple Flagellatae * known as
Spumella vulgaris, Cienk., and Chromulina. In these species the spore is formed,
as in the Bacteria in question, inside and from a portion of the protoplasm of a
cell, and this mode of formation occurs nowhere else among the lower Thallophytes.
We may at least suspect that a homology is indicated by this in itself only analogous
phenomenon, but the facts which have been observed lend no support to the
assumption. In dealing with this question we must keep well in mind that we are
not equally well acquainted with all portions of the range of organisms included
under the name Flagellatae, especially as regards the course of development of the
species, and that their affinities must be to some extent obscure and uncertain. For
this reason we will not add anything further to the remarks which have now been
made.

But if we assume for a moment a connection between the Bacteria and the
Flagellatae, it is evident that as a consequence the following series of forms converge
to the Flagellatae: firstly, the series of Bacteria and Nostocaceae; secondly, that
of the Mycetozoa (see page 445); Zhirdly, that of the chlorophyllaceous Algae,
with which are connected in ascending line the main series of the vegetable kingdom
and of the Fungi as one or more lateral branches‘, and perhaps also side by side
with the chlorophyllaceous Algae some smaller groups which are now placed with
the -Chytrideae ; fourthly and lastly the Rhizopoda and the Protozoa with the
Animal Kingdom which connects with these in an ascending line. On the above
assumption the position of the series of Bacteria in the whole system would be the
definite one of a gropp of organisms linking with the Flagellatae as a common
point of commencement and departure, and coordinating with the series of the Algae

"2 Bot. Ztg. 1881, 1. 2 Bütschli (as cited on page 453), p. 808.
3 Cienkowskiin Schulze’s Archiv f. mikr. Anat. VII, p. 434.—Biitschli, (as cited on page 453),

PP. 797, 816, t. 45.
* Bot. Ztg. 1881.

476 THIRD PART.—BACTERIA OR SCHIZOMYCETES.

or Mycetozoa. This would not affect the relations between the Endosporous and
Arthrosporous Bacteria, or between the latter and the Nostocaceae; nor can there
be a doubt that the Nostocaceae which contain chlorophyll and phycochrome are
in any case further removed from the Flagellatae than the allied species of Beggiatoa
and other arthrosporous forms, and that they therefore occupy the other extremity
of the whole series, which has received the name of Schizophytes and is the more
remote from the supposed point of departure.

With respect to the coordination of the Endosporous Bacteria and the rest of
the Schizophytes, we can only repeat what has been already said, that the final
determination of the point must be deferred till we are in possession of more perfect
knowledge of single forms.

CHAPTER XI.—MOoDE OF LIFE OF THE BACTERIA.

Section CXXXIV. Capacity of germination and power of resistance in
the spores. All spores of Bacteria in which the point has been investigated are
capable of germination from the moment that they are mature, provided that the con-
ditions are favourable. If prevented from germinating they show wonderful power
of resisting the external agencies which are usually pernicious or fatal to living
organisms, and individual spores show this power in different degrees in different
species.

These points have not yet been sufficiently investigated in the Arthrosporous
Bacteria. Kurth? found that the spores (‘cocci’) of his Bacterium Zopfii are killed
in from 17-26 days, when dried in a moderately high temperature (37° C.) and
then kept in an air-dry state at the ordinary summer temperature, while the vegetating
rods of the same species died in 7 days when subjected to the same treatment.
In a heated fluid their death-point is about 56°C. Similar small powers of resistance
to desiccation and high temperatures would probably be found in most of the
forms, such as Beggiatoa and Crenothrix, which are adapted to vegetate in water.

On the other hand the spores of many endosporous forms are instances of the
highest powers of resistance. Those of Bacillus subtilis retain their vitality for
years when kept in an air-dry condition, and those of B. Anthracis will remain
alive, according to Pasteur *, in absolute alcohol and after being exposed for 21 days
to the influence of pure oxygen compressed by a pressure of ten atmospheres. We
have no precise observations extending over larger periods of time, but Brefeld
found the power of germination unimpaired after the lapse of three years when the
spores were kept in an air-dry condition, after the lapse of one year when they had
lain in water; and from these facts as well as on account of other characteristics to
be noticed presently, we may safely assume that their powers of resistance are at
least equal to those of the most resistent spores of Fungi (page 344). The spores of

1 Bot. Ztg. 1883, 409.
2 Charbon et septicémie (Comptes rendus, 85 (1877), p. 99).

CHAPTER XI.—MODE OF LIFE OF THE BACTERIA. 477

the Bacillus in question also possess wonderful powers of withstanding extremely
high temperatures. Even in a fluid they are proof against a temperature higher
than that of boiling water. Brefeld! found that they all germinated after being
boiled for a quarter of an hour in a nutrient solution, the greater part of them after
half an hour of the same treatment, a smaller number after the space of one hour, none
when the boiling had continued for three hours. When spores were heated in
nutrient solutions up to 105° C. they were killed in 15 minutes, up to 107°C. in 10,
and up to r10°C. in 5 minutes.

Fitz found in 1882 that the spores of his Bacillus butylicus (? B. butyricus of
Prazmowski) endured a temperature of 100°C. for a period varying from 3 to 20
minutes, according to the special quality of the spores and the medium employed.
Temperatures below 100° C. were sufficient to kill the spores when they were exposed
to them for a longer continuance. In solution of glycerine death ensued in 2-6
hours at a temperature of 95° C., in 6-11 hours at 90° C., in 7-11 hours at 80°C.;
vitality was not destroyed after exposure for 12 hours to a temperature of 70°C. The
power of resistance was less in a solution of grape-sugar; the spores were killed in
6 hours at a temperature of 90° C.

Buchner? found that some of the spores of the Bacillus of anthrax were killed
by being boiled in water for two and three hours, and that after four hours’ time they
were all dead. Those of Bacillus Megaterium retain their power of germination after
being boiled in water for a few minutes. Of spores of less certain derivation occurring
in ordinary waters Pasteur states that they can even withstand a temperature of 130°.

These facts, and statements of a similar kind occurring in publications on
Bacteria, make it probable that the death-point for the spores of the Endosporous
Bacteria is generally very high, though it varies with the nature of the medium.
But here as elsewhere results obtained in one case must not be at once assumed
to be certainly true in others, since Brefeld in the work from which we have
quoted has shown that the spores of a form of Bacillus, not B. subtilis, will not live
in boiling water.

That the spores of Bacteria are able to bear extremely low temperatures has not
been proved by direct experiment, but may be concluded from the behaviour of the
vegetating cells which will be considered below.

The account given in section XCVI of the external conditions of germin-
ation is also generally true of the Bacteria, and to this the reader is referred.

The minimum and optimum temperature required for germination
especially in the Endosporous Bacteria appear to be usually high, other conditions
being equally favourable ; at least most of the experiments show that germination does
not take place or is very slow in the temperature of an ordinary room, and becomes
active only when the temperature is raised. In the case of Bacillus subtilis the
minimum is certainly below the temperature of an ordinary room, for germination
proceeds in it, though slowly. According to Prazmowski from 30°-35°C, is
near the optimum ; I myself have seen spores some days old germinate in the most
vigorous manner in a temperature of 40° C. three hours after they were sown. Bacillus

1 Schimmelpilze, IV.
? See Nageli, Unters. ii. niedere Pilze (1882), p. 220.

478 THIRD PART.—BACTERIA OR SCHIZOMPYCETES.

Anthracis will not germinate, as far as is known, in the temperature of a room
oscillating about 20°; the minimum is said to be from 35°-37°C., and the
optimum can scarcely lie much higher. On the other hand dried spores of Bacillus
Megaterium several days old germinated without exception in a summer temperature
of 20°-25°C. in 8-10 hours after they were sown. The cardinal point is not yet
completely established, but the foregoing data suffice to justify the general statements
in the introduction to the chapter, and also to show that specific differences exist
in the Bacteria as in other groups, and must be investigated in each case.

All spores of Bacteria which have been examined resemble those of the Fungi
described in page 351 in requiring for their germination a supply of proper nutrient
substances in addition to the water which they absorb; they germinate therefore
only in nutrient solutions or on a substratum containing water and a nutrient
substance. Observation has shown hitherto that the food required to induce
germination is qualitatively the same as that which is necessary for vegetative
development; at least germination takes place when this food is present, and we do
not yet know whether it can take place under other conditions.

Section CXXXV. The general conditions and phenomena of vegetation
in Bacteria are, as might be expected, analogous with or like those in other plants,
especially the Fungi (see section XCVII).

Although comparatively few cases have been carefully examined to determine
the relation of temperature to vegetation in Bacteria, it would seem that the range
of temperature is great and the optimum usually high.

Brefeld! determined the activity of the vegetative process at different tem-
peratures by observing in specimens that were well supplied with nutriment how
long a time elapsed before a division took place in a rod. He found that with
a parity of conditions a rod formed a division every half-hour when the temperature
of the air was 30°C., every three-quarters of an hour at 25°C., every hour and a-half
at 18.75°C., and every 4 or 5 hours at 12.5°C., while at a temperature of 6.2°C.
the vegetative process was extremely slow. The formation of spores required
about 12 hours at a temperature of 30°C., an entire day at 22.5°C., two days at
18.75°C., and several days when the temperature was not above 12.2°C.; below
6°C. no spores were formed. Vegetation continues active, according to Cohn? and
Prazmowski, at a temperature of 40°-50°C., and is accompanied with energetic
movement of the rods.

‘Bacterium Termo’ grows and vegetates according to Eidam* between the
temperatures of 5.5°C. and 40°C.; its optimum is 30°-35°C. Koch* states of
the Bacillus of anthrax, that in gelatine cultures its growth and spore-formation
are finest and most vigorous at a temperature of 20°-25°C. Between 30°C. and
40°C. its growth and the formation of new spores usually come to an end in
24 hours; up to 25°C. the time required for this increases till it reaches 35-40 hours.
Below 25°C. the decrease in the temperature is very marked in the negative sense ;
at 23°C. 48-50 hours are required for forming the spores, and at 21°C. 72 hours.
At 18°C. the first spores appear after about 5 days, at 16°C, after 7 days, and the

1 Schimmelpilze, p. 46. 2 Beitr. z. Biol. II, 271. ® Cohn’s Beitr. z. Biol. I, 3, p. 228.
* Mittheil. aus d. k. Gesundheitsamte, I, p. 64.

CHAPTER XI.—MODE OF LIFE OF THE BACTERIA. 479

spore-formation becomes constantly more sparing. Growth and formation of spores
cease below a temperature of 15°C. Fitz by comparing the forms in a mixture
which had completed its fermentation in the same time at different temperatures
found that the optimum of his Bacillus butylicus in solution of glycerine was 40° C.,
that of another species unnamed and grown by itself 37°-40°C. The maximum in
both species was 45°-45.5° C.

The upper limit of temperature at which vegetating Bacteria can continue
to exist appears to be little higher than that observed in the case of most other
plants. Cohn found that it approached near to the maximum of vegetation in
Bacillus subtilis, being 50-55°C. Fitz found it in the second of his two species just
mentioned at about 56°C. According to Eidam, ‘ Bacterium Termo’ was killed when
the liquid in which it was vegetating was heated during 14 hours up to 45°, and
during 3 hours to 50°. From Buchner’s experiments mentioned above with the
Bacillus of anthrax it appears that the dried rods are killed at the same degree
of temperature as the spores. Further details will be found in special works on
the Bacteria’.

The vegetative forms of the Bacteria are able to bear the lowest temperatures
to which they can well be exposed. Frisch? found putrefactive Bacteria and
species of Bacillus, among them B. Anthracis, still retaining the power of develop-
ment after being frozen in liquid at a temperature of —111°C.

It is in accordance with the analogy of other organisms that the temperatures at
which Bacteria vegetate and lose their vitality should vary with the character of the
substratum. Nägeli says? that by making changes in the nutrient solution the death
of the Fission-fungi may be ensured within a certain time at any temperature between
30° and 110°, but he does not distinguish here between germination of spores and
vegetative states.

The Bacteria differ much from one another in respect of the necessity for a
supply of oxygen. At one end of the series the vegetation is promoted in the
highest degree, other conditions being the same, by the largest possible supply of
atmospheric air containing free oxygen; this is the case with Bacillus subtilis, and
Arthrobacterium aceti; at the opposite end, as in B. butyricus, it is promoted by the
exclusion of free oxygen. Accordingly Pasteur distinguishes between aerobiotie and
anaerobiotic vegetation or forms *.

Cases have been observed by Engelmann ® lying between these two extremes, in
which a less pressure of oxygen is required than that which is afforded by the com-
position of the atmosphere. According to Nägeli® the aerobiotic forms will also
vegetate when deprived of a supply of free oxygen.

As regards the proper nutriment of Bacteria it is to be presumed that those
which have the green colour of chlorophyll, if they really contain chlorophyll

1 See also Pfeffer, Physiol. II.

* Sitzgsber. d. Wiener Acad., Mai, 1877.

5 Die niederen Pilze &c. (1877), p. 30, and see also p. 200.

* See also on this point Nencki in Journ. f. pract. Chemie, neue Folge, XIX, XX; also Genning
in the same publication.

5 Bot. Ztg. 1882, 321.

® Die niederen Pilze (1877), p. 28.

480 THIRD PART.—BACTERIA OR SCHIZOMYCETES.

assimilate carbon dioxide; and this is confirmed by Engelmann’s observation *
that Bacterium chlorinum gives off a small quantity of oxygen in the sunlight.

Nägeli’s researches show that the Bacteria which contain no chlorophyll generally
require the same kind of food as the Moulds which have been examined, and that the
organic compounds employed as food exhibit the same scale of feeding power in
the one case as in the other (see section XCVIII); but of inorganic nitrogenous com-
pounds nitric acid serves as food for the Bacteria, though in a less degree than ammonia.

Bodies which are contained in solution in the substratum but are not nutrient
substances may greatly influence the vegetation of the Bacteria. It was observed
above (p. 354) that an acid reaction in the nutrient solution is as a rule unfavour-
able to the development of the Bacteria. Some species however can put up
with this state of things to a certain point if they are by themselves in the
solution. But their vegetation may be entirely stopped by it, and so Moulds or
sprouting Fungi present with them in the fluid may thrive on thc acid and overpower
the Bacteria. Other bodies, which are products of the decomposition of the sub-
stratum caused by the Bacteria and pass into the solution, may also impede the vege-
tation as soon as they acquire a certain degree of concentration in the solution.
According to Fitz’s observation in 1882, the vegetation of Bacillus butylicus in
glycerine solution under otherwise optimum conditions was stopped by 2.7-3.3 per
cent. of ethyl alcohol, by 0.9-1.05 of butyl alcohol and by 0.05-0.1 of butyric acid, &c.

It should be observed here that bodies which serve as food, and in the case of
the aerobiotic forms the oxygen also, act as stimulants on the Bacteria, awakening or
accelerating their powers of movement and determining its direction. Engelmann?
has shown that sensitive aerobiotic Bacteria are brought to rest by cutting off the
supply of oxygen, and are at once set in motion again by renewing the supply, and
the movement is directed towards the source of the oxygen, for example a cell
containing chlorophyll which is reached by the sun’s rays. An infinitesimal portion
of an oxygen-compound, according to Engelmann’s calculation the trillionth part of
a milligram, is sufficient to set very sensitive aerobionts in motion, and they are there-
fore the most delicate of reagents for the evolution of oxygen. Such sensitive forms,
when the oxygen is supplied to them from one direction only, move as close as possible
to the source of the oxygen, such as a cell containing chlorophyll or the edge of the
cover-glass when a specimen is grown in drops ofa fluid on a microscopic slide.
Other forms under the same conditions only approach within a certain distance of the
source of the oxygen, and this distance increases as the oxygen diminishes. From this it is
concluded that these forms can do with a pressure of oxygen less than that of the atmo-
sphere. Anaerobionts behave in this respect in the reverse way to that of the sensitive
aerobionts. The movement of motile forms in fluids is similarly quickened by a
supply of proper soluble nutrient material, and it is directed, if the supply comes from
one side, towards the diffusion-stream of the nutrient solution which flows into the liquid
substratum from the source of the supply. Hence the Bacteria gather in dense swarms
round solid bodies containing nutrient substances when placed in the fluid in which
they happen to be present °.

1 Bot. Ztg. 1882. ? Bot. Ztg. 1881, p. 441; 1882, pp. 663, 419.
g P . P 419
> Further details will be found in Pfeffer in Unters. d. Bot. Inst. z. Tübingen, I, Heft 3.

CHAPTER XI.—MODE OF LIFE OF THE BACTERIA. 481

Section CXXXVI. The Bacteria, apart from the forms which contain chlorophyll
and which have not yet been carefully studied, are distinguished according to their
actual vegetative adaptation into saprophytes and paraszies, in the sense in which the
words were employed in section XCIX.

The adaptation of the saprophytic forms presents the same general points of
view as that of the saprophytic Fungi. Many Bacteria are, like these Fungi, to some
extent organisms which produce oxidarions, combustions of the substratum. The
Micrococcus of vinegar or mother of vinegar (Arthrobacterium aceti, Mycoderma
aceti) oxidises ethyl alcohol in atmospheric air and converts it into acetic acid; but
it may also convert it by combustion into carbonic acid and water’. Bacillus subtilis
and as it would appear B. Megaterium also cause similar combustion of organic com-
pounds and produce carbonic acid and water. Many others excite characteristic
JSermentations, lactic acid fermentation, butyric acid fermentation and the viscous
fermentation of sugar, &c., they also act as inciters of pusrefactive processes. For the
details of these phenomena, which are the subject of so much discussion at the present
day, the reader is referred to the special literature of the Bacteria and of the chemistry
of fermentation, to the excellent researches of A. Fitz especially, and those of Nageli
and Duclaux, and to Pfeffer’s Physiologie, I, chap. 8.

Many Bacteria on the other hand are parasitic in and on living organisms.
In the determination and description of their mode of life the same points of view
must be taken, and the same divisions and nomenclature applied, as those which were
explained at length in connection with parasitic Fungi in speaking of their relations to
their host and the effects they produce in it, for the same or quite analogous
phenomena occur in both cases. In the succeeding remarks therefore there is a tacit
reference throughout to sections CI-CXIII.

All parasitic Bacteria live as endophytes in the cavities of the body or in the
substance of the tissue of the host. Their structure and growth determine the mode
in which they attack the host; they find their way either as spores or in the vegetative
form into normal cavities of the body accessible from without or into wounds, and in
both places they continue a process of vegetation ; they may also be passively conveyed
from wounded surfaces in the bodies of animals into the blood and lymphatic passages,
or else they penetrate into the cells and tissue from any surface to which they have
been conveyed. The Bacillus of anthrax for instance penetrates into the mucous layer
of the intestinal canal 2, when it has been carried to it in the animal’s food. The
effects of fermentation will have something to do with the perforations thus produced,
and the direction of the movement will depend on the co-operation of the chemical
and physical qualities of the substratum and possibly of the spontaneous motion of
the parasite.

All known parasitic Bacteria are simply and for the most part vigorously
destruchve in their effect upon their host, if we do not in their case also reckon
inflammatory processes (the formation perhaps of tubercles) among phenomena of
diseased growth and new formation.

Bacteria parasitie on plants have scarcely ever been observed, a fact to which

1 Pasteur in Comptes rend. 54, p. 265, and 55, p. 28.—Nägeli, Theorie d, Gährung, p. III.
2 See Koch, Mittheil. d. Reichsgesundheitsamts, I, p. 61.

[4] , ri

482 THIRD PART.-—-BACTERIA OR SCHIZOMYCETES,

R. Hartig has already drawn attention. One reason for this may be that the parts
of plants have usually an acid reaction. At the same time Wakker! has recently
described a disease in the hyacinth known in Holland as the yellow sickness,
the characteristic symptom of which is the presence of yellow slimy masses of Bacteria
in the vessels. In the resting (autumnal) bulb the masses of Bacteria are confined
to the vascular bundles ofthe bulb-scales; at flowering time they are found also in the
leaves, and not in the vessels only but in the parenchyma also, where they fill the
intercellular spaces, destroy the cells, and ultimately emerge through the ruptured
epidermis and appear on the outside. The case demands a thorough investigation.

The Bacteria on the other hand which are parasitic in living animals are,
according at least to prevailing views, comparatively numerous, and the most
prominent feature in them is their facultahve parasitism. Of this we have instances
which have been investigated with some care and may be considered as well
established, and it will be well to give here a special account of one of the most
important of the number, namely Bacillus Anthracis.

The structure and development of this species have been already portrayed in
Fig. 195. It attacks the Mammalia, especially rodents and ruminants, with the
exception of some species and individuals; mice, guinea-pigs, rabbits, sheep and
cattle are unequally liable to be infected by it in the descending order. It will also
attack human beings. It is communicated with difficulty to dogs, more readily to
cats. Observers are not agreed as to the degree of liability of birds, frogs and fishes
to be infected with it, and we cannot further discuss their statements in this place.
We know from Rayer, Pollender and Davaine that it causes the disease known as
anthrax in the animals first mentioned. My own experiments on which this account
is partly based were chiefly made on guinea-pigs, and on material obtained from
them.

When the Bacillus has gained admission into the blood of an animal capable of the
infection, it grows and multiplies in the rod-form described above to such a degree
that the entire mass of the blood is permeated by these organisms. The animal
sickens as the Bacillus multiplies and the result is usually fatal. The Bacillus may
find its way into the blood directly by intentional introduction of rods or spores or
from accidental wounds; a prick of a needle charged with rods or spores, so slight
as not to draw blood, is sufficient to give the infection to a sensitive animal. But it
may also reach the blood from the intestinal canal, into which it is conveyed in the
natural way only, that is through the mouth with the food. Rods introduced in this
way have no further effects, if the digestive passages are without a wound; they
probably perish in the acid contents of the stomach. But if spores are introduced the
animal takes the infection. The spores pass unharmed through the acid stomach
and germinate in the alkaline contents of the intestinal canal, and the rods which are
the product of germination are found in the mucous membrane of the canal, having
forced their way probably through the lymph-follicles and Peyer’s patches, as Koch
supposes. From hence the way is open through the capillaries into the blood-.
passages.

According to Koch’s investigations the infection comes much more frequently

1 Bot. Centralblatt, 14, p. 315.

CHAPTER XI. —MODE OF LIFE OF THE BACTERIA. 483

from the intestinal canal in cases of anthrax arising from natural causes, that is, not
artificially produced. But to understand the life-history of the Bacillus and with it the
aetiology of the disease, we must first enquire how the spores find their way into the
intestinal canal. It cannot be directly from a diseased or lately deceased animal,
because the Bacillus forms its spores neither in the living creature nor inside the
unopened carcase *. But it is evident from what has been said on page 466, that the
Bacillus may not only germinate and vegetate luxuriantly outside the body of
the animal, but that the formation of spores takes place there almost exclusively, or
at least, as is proved by every culture-experiment, in the greatest abundance, if there
is a proper supply of oxygen and a temperature of 20°-25°C. A sufficient further
supply of nutrient substances must also be presupposed, and experiment has shown
that these are found in abundance in every variety of dead organic bodies, and
not only in substances of animal origin, such as the solid and fluid parts of animals
themselves that have died of anthrax, or the bloody excreta of those that are ill of the
disease, but also in vegetable bodies in which the reactions are not too acid, such
as potatos, beetroot or crushed seeds, &c. It is evident from this, that the Bacillus
is not only able to live as a saprophyle, but that it must adopt that mode ‘of life in
order to arrive at a section of its existence of the greatest importance morpho-
logically and biologically, namely that in which it forms its spores. It appears
further that it can and does readily find the necessary conditions for its vegetation
as a saprophyte on the surface of a moist pasture-ground, when it has once found its
way there, and can maintain itself there from year to year by means of ils spores
and of the rods which dry up or are frozen in unfavourable vegetative periods;
it is not necessary that the place should be visited by animals. We may readily
conceive, how graminivorous animals liable to infection may take in the spores of the
Bacillus with their food in such places and become infected, for the Bacillus has the
capacity of parasitism. In the case of cattle that feed in herds, if one falls sick others
quickly take the infection and the disease becomes epidemic, because the number of
Bacilli on the ground is increased by the addition of those in the bloody excreta of
the sick animals, the pasture being thereby rendered more dangerous for the herds,
and because stinging flies and the like may directly inoculate one animal with the
Bacilli contained in the blood of another.

It is obvious that under these conditions an animal is in greater danger of
infection if it has wounded surfaces whether of the skin or of the mucous membrane
of the mouth and digestive canal.

Our experience with the domestic animals has taught us that anthrax is endemic
in certain localities, and breaks out there spontaneously, at first attacking single
animals, apparently without direct infection from others but usually starting from
the intestine, and afterwards spreading to other individuals, It is not easy to
explain why separate districts should thus be the favoured home of anthrax, and why
an organism which seems to be so capable of dissemination should not be found
everywhere and be everywhere alike capable of producing disease. The reason may
be, as Koch supposes, that the dangerous localities are wet and liable to be flooded,
and that the Bacillus grows more abundantly on wet ground than on dry, and is also

1 See Koch, Mittheil. d. Reichsgesundheitsamts, I, pp. 60, 147.
1i2

484 THIRD PART.—BACTERIA OR SCHIZOMYCETES,

raised above the surface of the soil by the floods and spread over the plants which are
subsequently eaten by the cattle. It is at the same time possible that the Bacillus
may also be conveyed to the localities by the bodies of animals which have died of
anthrax. This would at all events be more likely to happen in a district which has
once been much infected with the fever than in any other. Mice are very susceptible
to the disease, and the dead bodies of these creatures and of other small rodents
would be especially calculated to propagate the infection. But Pasteur’s sensational
hypothesis, that the Bacillus is introduced into the soil by the burial of the bodies of
infected animals, and that its spores are then conveyed by earth-worms from beneath
to the surface, is not necessary for the explanation of the phenomena in these or any
other localities; it is moreover open to the objection that the formation of spores
never or scarcely ever takes place, as is urged by Koch, in the unopened body of an
animal in the temperature of the deeper layers of soils and with the small amount
of oxygen in the air which they contain.

The Bacillus here described is shown by its life-history to be a strictly facultative
parasite, which only reaches the highest stage of its development in the non-parasitic
state, and not only can but actually often does go through the entire course of
its development in this state during many generations and even many years. It has
been shown that it has a virulent effect at least on the animals above mentioned.
Whether it can vegetate in other species of animals without doing them harm is not
yet ascertained. But its virulent effects on those animals which suffer from its
presence may be diminished by certain methods of breeding, and indeed be weakened
till they become quite innocuous. Pasteur first discovered through his experiments
on fowl-cholera, and Koch? confirmed his results, that this takes place when the
Bacillus is grown in a neutralised nutrient solution, such as a meat-broth, with
a plentiful supply of oxygen and at a high temperature. The attenuation of the
effects may be carried so far that a mouse, the most susceptible animal with which
experiments have been made, can suffer inoculation without being made ill; the
attenuation is induced rapidly when the temperature is raised to nearly 43°C. and may
be completed in 6 days; at a temperature of 42°C. the cultivation may require to be
continued during 30 days, and the process is still slower in the temperature of an
ordinary room. The Bacillus vegetates under these conditions and multiplies without
alteration of its morphological characters, but 27 does not produce spores. Cultures
kept at a temperature of 42°-43°C. perish in about a month’s time, but fresh cultures
can be obtained from them from 1-2 days before that time has expired. The Bacillus
may recover its virulent properties after a certain degree of attenuation, if it finds its
way into an animal which is susceptible to the infection and kills it. There is
a degree of attenuation in which it is innocuous to full-grown guinea-pigs, but not to
very young ones; if the latter are inoculated with the attenuated matter, the Bacillus
returns to its state of greater virulence. The data before us do not show whether a
return to virulence is possible from the highest degree of attenuation, nor have we any
distinct experiments to prove whether the attenuated Bacillus developes at all in the
animal which is inoculated with it but continues healthy, or in what manner it developes.
It has been assumed that it does develope there, but there are no precise facts on

1 See his essay, Ueber d. Milzbrandimpfung, Cassel, 1883, p. 17.

CHAPTER XI. —MODE OF LIFE OF THE BACTERIA, 485

which to ground the assumption ; but enough is known for the determination of the
practical question of protective inoculation by means of the attenuated Bacillus. We
cannot however enter further into this point here, but must refer the reader to medical
works on the subject.

Be this as it may, it is easy to conceive, in the case of a facultative parasite which
is able to adapt itself to nutrient solutions of different concentration and qualitative
composition at a temperature of 15°-20° C. and to the blood of a mammal at one of
37°-40° C., that changes in the adaptation and food may be followed by changes in the
deleterious effects, which may be supposed to be due to the production of some kind
of ferment. An analogous though quantitatively different case is that of Sclerotinia
Sclerotiorum described on page 380, in which the capacity for a parasitic life depends
on the food supplied to the plant in its young state. We may also compare the
Mucorini (page 358), which vary their form and the decomposition which they
produce with the medium in which they live, and the Bacterium described by
Wortmann’, which gives rise to a ferment capable of dissolving starch if it is supplied
with nothing but starch-grains for its food, but ceases to produce the ferment if fed
with carbohydrates in solution or with ammonium acetate.

In the foregoing description it has been tacitly assumed that Bacillus Anthracis
is a distinct species, and the present state of our knowledge requires the assumption.
The Bacillus of anthrax has a resemblance to other species, and among them to
Bacillus subtilis, which is not a facultative parasite or at least may under certain
conditions be a harmless parasite; it varies also in the breadth and length of its cells
and in other respects; but it always remains within the limits of the specific
characters, the most important of which are given on page 466, and which distinguish
it from other species and especially from B. subtilis also described above.

Buchner has maintained, in opposition to this view, that the Bacillus of anthrax
and the hay-bacillus may be made to pass one into the other by breeding, and that
they are therefore only states of one and the same species. He has not supplied us
with the strictly morphological proof necessary to establish this opinion, since he has
not taken into consideration the behaviour of the spores of his altered forms
in germination, at least in his published communications, and yet this is one of the
characteristic marks of distinction. He adopted also the macroscopic mode of
cultivation, in which it is not possible to ensure an uninterrupted control of the
continuity of the development, or of the accidental mingling of different species.
His transformation of the virulent Bacillus of anthrax into the supposed innocuous
hay-bacillus was effected in cultures at a high temperature and with a more
than ordinary supply of oxygen; the temperature was 36°C., the apparatus
employed ensured constant shaking in air, and the solution contained 0.5 per cent.
of meat-extract. The transformation was not obtained at a temperature of 25°C.
and when the apparatus was not kept in motion. It was evidently Pasteur’s inno-
cuous state which was produced in this case, but that is by no means Bacillus
subtilis. The results of the reverse transformation appear, according to Buchner’s
own account, extremely doubtful. Now that the facultative parasitism and the
possible change of virulence in Bacillus Anthracis have been demonstrated, and since

1 Zeitschrift f. physiol. Chemie, VI, p. 287.

486 THIRD PART.—BACTERIA OR SCHIZOMFCETES.

it has been further established that species can be distinguished in the Bacteria
as in other organisms, the whole controversy has lost the importance which it was
once supposed to have.

In Buchner’s experiments on the change of the hay-bacillus into the Bacillus of
anthrax, Bacillifrom an infusion of hay were bred with certain precautions in fresh blood.
The macroscopic character of the masses of Bacilli was changed, and intermediate
forms were obtained between the hay-bacillus and the Bacillus of anthrax, and strange to
say no reversion was obtained in the intermediate forms when solution of meat-extract
or infusion of hay was substituted as the nutrient fluid. Mice and rabbits were inocu-
lated with the altered matter, and some of the creatures experimented on sickened and
died of anthrax, but much the larger number did not take the infection. Koch will not
allow that the observed disease was true anthrax, and maintains that it may have been
a disease which is common in mice and cannot always be at once distinguished from
anthrax—a disease known as malignant oedema, and produced by a Bacillus morpho-
logically very like the Bacillus of anthrax, which must have found its way into the
culture with the hay-bacillus. If we allow that the disease in the cases actually ascer-
tained was anthrax and disregard Koch’s doubt on the point, the things to be remembered
are chiefly these. By far the largest part of the original material used for the experiment
may have been ascertained to consist of Bacillus subtilis ; but we have no proof that
other Bacilli, lost at first in the overwhelming mass of B. subtilis and practically not
distinguishable from them, were not contained along with B. subtilis in the hay-infusion.
It would indeed be wonderful if one species, B. subtilis, were on all occasions the
only form obtained without admixture of any others from a material like hay treated
according to a definite procedure, especially as the apparently exceptional security of the
procedure, the boiling the hay, offers no certain guarantee, because the spores of other
Bacteria as well as Bacillus subtilis are capable of withstanding that temperature.
Bacillus subtilis then may be present in the hay-infusion in much the larger numbers,
and the forms mixed with it may be comparatively few. But we have to ask whether
this numerical relation may not be altered or even reversed in other nutrient fluids, for
instance in blood, whether single spores of Bacillus Anthracis may not have been pre-
sent in the original material and only after change of cultivation have been in a condition
to produce a small quantity of infectious material among the individuals of the other
species, and thus occasional cases of infection may have occurred among the instances
of failure; to these questions the data before us afford no certain answer. Allusion has
been already made to Koch’s views, and we will not draw attention here to other points
of difficulty. The reader is referred for further particulars to the original publications.

The Bacillus of anthrax has been discussed at some length because it is at
present the best-known example of the Bacteria which inhabit the bodies of animals
and incite disease in them. Modern pathology resting on older observations and
experiments, among which the researches into anthrax itself occupy a prominent
position, and supported by Nageli’s theoretical considerations, endeavours to refer all
infectious diseases in animals, excepting the few that are caused by Fungi (p. 376)
and some that were not formerly supposed to be infectious, to the invasion of Bacteria
as their proximate cause. These organisms have been sought for sometimes with
great, even with excessive zeal, and some have been found. The parasitic qualities, in
virtue of which many of these organisms incite disease, have been sufficiently proved
in a number of cases, for example in septicaemia, erysipelas, recurrent fever in warm-
blooded animals, Pasteur’s fowl-cholera, the flacherie of the silk-worm, though our
botanical knowledge of the plants themselves is still very defective. Some forms are
still the subjects of lively discussion on the part of experimental pathologists. Bacteria

CHAPTER XI.

MODE OF LIFE OF THE BACTERIA. 487

occurring in a living or dead body are not necessarily the inciters of disease, and the
attempt to decide the point experimentally often encounters great difficulties. To
expatiate further in the domain of pathology would carry us beyond the limits to
which we are confined. But we shall perhaps contribute something of value to the
above-mentioned discussion as well as to the determination of the recognised cases
if we append a few short general remarks to the foregoing account of anthrax. For
further details the reader is referred to medical works and to the compilations of
Marpmann and Zopf, which are not however as complete as might be wished.

So far as can be judged from the accounts before us, all the Bacteria which are
suspected of being or are proved to be parasites with the power of inciting disease,
with one exception which will be noticed again below, are capable of vegetating and
being bred in dead organic matter ; some form their spores chiefly or exclusively in
this saprophytic stage of their development. The Bacteria of the latter category
are therefore facultative parasites like the Bacillus of anthrax, and the rest perhaps
are so too; if not, they are at any rate facultative saprophytes. Hence they can both
vegetate, like the Bacillus of anthrax, outside the living animal; the localities must
be ascertained in each separate case, and it follows that the danger of infection is
different in this case and in that of obligate parasitism.

Further it will depend on the species, race and individual among the Bacteria in
question in their quality of parasites what hosts they will choose, as is the case with
the Bacillus of anthrax; or conversely, some species of animals or some individuals
will be more liable to be attacked by a given species of Bacterium, while others will
be secure from it. It is at the same time conceivable that this condition may vary in
individuals, an individual not before susceptible may for instance become susceptible ;
this may be due to external causes whether otherwise injurious or apparently
indifferent. We have sufficient proof that such changes do actually occur.

As the disposition of the host may vary, so also a change may take place in the
qualities, and specially in the virulence of the parasite, as we see in the case of the
attenuated Bacillus of anthrax. This may perhaps be assumed to be the general rule
in the forms which approach near to that species and of which we are here speaking.
The change may be in the direction of loss of virulence, or on the contrary of its
recovery. It may therefore also happen, that experiments in artificial infection with
the same forms of Bacterium may, ceteris paribus, yield different results, some of a
positive, others of a negative character. It is possible that the great difficulty or
impossibility of obtaining animals that are exactly alike for experiments may az least
help to heighten the apparent contradictions.

The investigation of the Bacillus of anthrax has further shown that the changes
just mentioned may be accomplished in a form which would be considered by a
naturalist as distinctly sdecifc, and which at the same time maintains its specific
characters within the limits of variation to which it is subject. Such changes there-
fore afford no ground for doubting the existence of distinct parasitic species. From
all other trustworthy sources of knowledge we obtain the same testimony, that real
species can and must be distinguished in the Bacteria exactly as in other groups of
plants and animals, and that the parasitic forms which incite disease do not differ in
this respect from the rest. Nägeli’s words’, ‘if my view is correct, the same species

1 Niedere Pilze (1877), p. 64.

488 THIRD PART.—BACTERIA OR SCHIZOMYCETES.

assumes in the course of generations various morphologically and physiologically
unlike forms one after another, and these forms, in the course of yearsand decades of
years, may produce souring in milk, butyric acid in sauerkraut, ropiness in wine, putre-
faction in albumen and decomposition in urine, may turn articles of food containing
starch red, and give rise to diphtheria, to typhus, to recurrent fever, to cholera, to
intermittent fever’—these words or the view which they embody would not have been
published even in 1877, if their author had studied the forms in question, and especially
the parasitic forms, with greater attention. At the present day, when our knowledge
of the facts is still more advanced, such a position can no longer be maintained. It
is specially in the domain of the parasitic Bacteria that investigation has established
more and more distinct species, and shown that every disease incited by a parasite
which has been thoroughly examined may be traced to a definite form of Bacterium,
of the specific character of which there can be as little doubt as of that of a large Fungus
or of a worm. The assertion that there are distinct species of parasitic Bacteria, and
that every special disease caused by Bacteria is the work of a distinct species, is not
merely a convenient form of statement, as Nageli thinks, but it is the only one which
is in unison with the /ac/s as at present known.

If a species like the Bacillus of anthrax also vegetates as a saprophyte, it is
obvious that it may set up different processes of decomposition in the dead substratum
from those which constitute disease in a living body. Further, if diseases supposed to
be due to the presence of Bacteria ‘have a limited duration in the history of the
human race, change, arise and disappear,’ this is no objection to the observed facts
but merely a reason for making special efforts to explain them ; and accepting the
fact, equally well observed, that men as well as Bacteria may change some of their
qualities in the course of time and yet retain their specific characters unaltered, we
may suppose that the attempts at explanation will possibly in course of time be
successful.

It is uncertain whether there are obligate as well as facultative parasites among
the Bacteria, either species that are strictly obligate or some that have also a
narrowly limited power of saprophytic vegetation. The forms which may possibly
excite diseases that are strictly contagious, smallpox for example, should be tested
on this point. Mention must be made in this connection of Spirochaete Ober-
meyeri, one of the most characteristic parasites and an undoubted inciter of disease,
which appears invariably in the blood of those who are suffering from recurrent
fever. It has been successfully transferred from men to apes, but to no other species
of mammal on which the experiment has been tried. It has been attempted to
cultivate it outside the body of a living animal, but as yet without success !.

It is very doubtful whether the minute organism, Nosema Bombycis, Nägeli,
Panhistophyton, Lebert, which accompanies and according to Pasteur’s experiments
causes the destructive disease in the caterpillar of the silkworm known as pébrine or
gattine, belongs to this group. It appears in the form of small ellipsoid or somewhat
elongated peculiarly refractive bodies resembling Bacteria, which may penetrate through
all parts of the caterpillar and butterfly. We learn from Pasteur that it may find its

1 v. Heydenreich, Unters. ii. d. Parasiten d. Rückfalltyphus, Berlin, 1877.—Lachmann in
Deutschen Arch. f. klin. Medicin, 27, p. 52 b. ö

CHAPTER XI,—MODE OF LIFE OF THE BACTERIA, 489

way into the membrane of the intestinal canal if supplied to a healthy caterpillar with
its food, appearing there first singly and then multiplying rapidly and spreading
through other organs. Its development and even its mode of multiplication, which is
said to be by bipartition, is not yet clearly ascertained, and we can only affirm with
Pasteur that it is a highly dangerous parasite, and expect more distinct conclusions
from further investigations!.

The above case must,not be confounded with the forms of disease included under
the name of flacherie. These are due, according to Pasteur?, to the disturbances
in the digestive process caused by decomposition or fermentation of the food in the
intestinal canal, through the presence of an endosporous rod-shaped Bacterium and a
chain-forming Micrococcus, the M. Bombycis of Cohn*. Doubtless this is a case
of facultative parasitism, though further investigation is desirable.

LITERATURE OF THE BACTERIA.

The literature of the Bacteria has increased to an enormous size in the last ten or
fifteen years. I have taken some pains to make myself acquainted with it, but I cannot
affirm that my efforts have been entirely successful. It is at present quite impossible,
especially in the medical part of the subject, for scientific criticism to keep pace with the
eager study of the Bacteria, while on the other hand it is not the object of this work to
supply a mere index.

For these reasons I have avoided first of all touching further on the medical side of
the question than was required to complete the account of the morphology and biology
of the Bacteria; and in the second place I abstain from attempting a complete enumera-
tion of the literature of these organisms. Copious notices of it are to be found in the
following works :—

A. MAGNIN, Les Bactéries, Paris, 1878.

W. Zopf, Die Spaltpilze, 2nd ed., Breslau, 1884, in Schenk’s Encyclopädie.

G. MARPMANN, Die Spaltpilze, Halle, 1884.

DucLAux, Chimie biologique (Vol. IX of the Encyclop. Chim. of Frémy,
Paris, 1883).

The lists of works in the last three books are far from being complete, but by
consulting them and the works which will be cited presently every student will find his
way to whatever part of the subject is of immediate interest to him. The reader there-
fore is referred to these publications as the most important, and after them to the medical
Journals, Annual Reports and recent Text-books, and finally to Just’s Botanischer
Jahresbericht ; and in the subjoined list I confine myself to noticing the chief sources
of information, which with my own researches have served as the foundation for the
account of the morphology and biology of the Bacteria given in the text. A few
works already quoted in the notes to the text and referring to special points are not
mentioned again below.

1. General literature of the Bacteria.

L. PASTEUR, Examen de la doctrine des gen. spontanées (Ann. Chim. ser. 3, 64, and
Ann, d. sc. nat., Zoologie, ser. 4, XVI, extracted in Flora, 1862, p. 355) ;—Id., Etudes
sur le vin, Paris, 1866 ;—Id., Maladies des vers & soie, Paris, 1870;—Id., Etudes
sur la biére, Paris, 1876.

1 Pasteur, Etudes sur la maladie des vers 4 soie, Paris (1870), I, p. 207. The earlier literature
of the subject will be found there. See also Frey u. Lebert in Vierteljahrsschrift naturf. Ges, Ziirich,
1856.—De Quatrefages, Mém. de l’Acad. des Sciences, XXX, 1860.—Leydig in Du Bois-Reymond’s
a. Reichert’s Arch., 1863, p. 186.—Hoffmann, Mycol. Ber. (Bot. Ztg. 1864, p. 30).

2 Etudes sur la maladie des vers & soie.

3 Beitr. z. Biol. I, 3, p. 165.

490 THIRD PART.—BACTERIA OR SCHIZOMYCETES.

Also communications of Pasteur, his pupils and opponents since 1858 in the Comptes
rendus of the Paris Academy. Among these the remarkable and finished treatise, Sur
la choléra des poules (Cptes. rend. go (1880), pp. 239, 952, 1030) should be especially
noticed. See also below in the second list.

F. COHN, Unters. ii. d. Entwicklungsgesch. d. mikroskop. Algen u. Pilze (Nov. Act. Acad.
Leop. 1854, 24, p. 1;—Id., Unters. ii. Bacterien (Beitr. z. Biol. d. Pflanzen, I, Heft 2,
p. 127, Heft 3, pp. 141, 208, II, p. 249.)—Koch, Schröter, Eidam, in the same
publication, Vols. I, II, Wernich, Miflet, Mendelsohn, Neelsen, in the same
publication, Vol. III).

L. CIENKOWSKI, Zur Morphol. d. Bacterien (Mém. Acad. St. Pétersbourg, XXV, No. 2,
1877).

E. WARMING, Obs. sur quelques Bactéries qui se rencontrent sur les cötes du Danemark
(Videnskab. Meddelelser fra Nat. Forening, Kjobenhavn, 1875-6).

R. KOCH, Zur Aetiologie d. Wundinfectionskrankheiten, Leipzig, 1878.

C. v. NAGELI, Die niederen Pilze in ihren Beziehungen zu d. Infectionskrankheiten,
München, 1877 ;—Id., Unters. ii. niedere Pilze a.d. pflanzenphysiol. Instit. z.
München, 1882.

P. VAN TIEGHEM in Bull. de la Soc. bot. de France, 26 (1879), pp. 37, 144, and 27 (1880),
pp..148, 174;—Id. in Ann. d. sc. nat. ser. 6, VII (Leuconostoc);—Id., Traité de
Botanique (1883), p. 1108.

E. C. HANSEN, Meddelelser fra Carlsberg Laboratoriet, I, Kopenhagen, 1878-82.

BREFELD, Bot. Unters. ii. Schimmelpilze, IV.

A. PRAZMOWSKI, Unters. ii. d. Entwicklungsgesch. u. Fermentwirkung einiger Bac-
terien-Arten, Leipzig, 1880, and in Bot. Ztg. 1879, p. 409.

A. F1Tz, Ueber Spaltpilzgährungen in Ber. d. Deutschen Chem. Ges. I. Jahrg. 9 (1876),
p. 1348.—II. J. 10 (1877), p. 276.—III. J. 11 (1878), p. 42.—IV. Ibid. p. 1890.—V.
J. 12 (1879), p. 474.—VI. J. 13 (1880), p. 1309.—VII. J. 15 (1882), p, 867.—VIII.
J. 16 (1883), p. 844.—IX. J. 17 (1884), p. 1188.

W. ZopF, Unters. ii. Crenothrix polyspora, d. Urheber d. Berliner Wassercalamität,
Berlin, 1879 ;—Id., Zur Morphol. d. Spaltpflanzen, Leipzig, 1882.

KURTH, Bacterium Zopfi (Bot. Zeitung, 1883).

MITTHEILUNGEN d. kais. Gesundheitsamts, I (1831), II (1884).

2. Anthrax.

O. BOLLINGER in Ziemssen’s Handb. d. speciellen Pathologie u. Therapie, III (1874),
and Pasteur, Comptes rend. 1877, 84, may be consulted for the earlier literature.

PASTEUR, Maladie charbonneuse (Cptes. rend. 84 (1877), p. 900) ;—Id., Charbon et sep-
tic&mie (Cptes. rend. 85 (1877), p. 99) ; see also Cptes. rend. 87 (1878), p. 47, and
Bull. de l’Acad. de Médecine, 1878, pp. 253, 497, 737 ;—Id., Chamberland et Roux,
Cptes. rend. 92 (1881), pp. 209, 429, 266, &c.

R. Koch, Die Aetiologie d. Milzbrandkrankheit (Cohn’s Beitr. z. Biol. II, 277) ;—Id.,
Mittheilungen a. d. k. Reichsgesundheitsamt, I.

H. BUCHNER in Nägeli’s Unters. ii. niedere Pilze, 1882 (see previous list).

OEMLER, Experimentelle Beitr. z. Milzbrandfrage (Arch. f. Thierheilkunde, II-VI).

ARCHANGELSKI, Beitr. z. Lehre v. Milzbrandcontagium (Centralblatt f. d. medicin.
Wissensch. 1883, p. 257).

ROLOFF, Ueber Milzbrandimpfung u. Entw. d. Milzbrand-Bacterien (Archiv. f. Thierheil-
kunde, IX (1883), p. 459).

EXPLANATION OF TERMS.

Abjection (Abschleuderung) of spores.
Throwing off with force of spores from
a sporophore.

Abjoint. To joint off or delimit by septa.

Abjunction (Abgliederung). Delimitation
by septa of portions of a growing hypha
as spores.

Abscise. To cut off or detach by solu-
tion of a zone of connection.

Abscision (Abschnürung) of spores.
Detachment of spores from a sporo-
phore by disappearance through dis-
organisation or otherwise of a connecting
zone.

Accessory gonidia. In Mucorini: goni-
dial formations found in some species in
addition to the typical ones of the group.

Actinomycosis. A disease in animals and
man characterised by the development
of tumours in the jaw-bone, vertebrae,
lymphatic glands and other places within
which sulphur-yellow bodies like sand-
grains occur, each consisting of an aggre-
gate ofan organism, Actinomyces, which
is supposed to be a Fungus.

Acrogenous. (a) Producing atthe summit.
(6) Produced at the summit.

Acrogonidium. Gonidium formed at the
summit of a gonidiophore.

Acropetal. In the direction of the summit.
Comp. basipetal.

Acroscopic. Looking towards the summit,
i.e. on the side towards the. summit.
Comp. basiscopic.

Acrospore. Spore formed at the summit
of a sporophore.

Adventitious. Produced out of normal
and regular order.

Aecidiospore. Spore formed in an ae-
cidium.
Aecidium. In Uredineae: sporocarp

consisting of a cup-shaped envelope
(peridium) and a hymenium occupying
the bottom of the cup from the basidia
of which spores (aecidiospores) are
serially and successively abjointed.

Aerobiotic. Organisms which require
for their vegetation a supply of free
oxygen are aeriobiotic. Comp. anaero-
biotic.

Aethalium. In Myxomycetes: com-
pound sporiferous body formed from a
large combination of plasmodia.

Algal layer. In heteromerous Lichens:
green band at the line of junction of the
rind and medulla of the thallus in which
the cells of the Alga of the Lichen are
aggregated. Same as algal zone, goni-
dial layer, gonimic layer, stratum
gonimon.

Algal zone. Same asalgal layer.

Alveolate. Pitted so as to resemble honey-
comb.

Amoeboid. Like an amoeba, i.e. a small
portion of protoplasm exhibiting creeping
movement by putting out and drawing in
pseudopodia.

Amylogenesis. Formation of starch.

Amylum-grain. Starch grain.

Analogous. Having the same function.
Comp. homologous.

Androgynous. Having male and female
sexual organs developed on the same
branch of the thallus. Comp. diclinous.

Androspore. Male spore, i. e. spore which
on germination produces a body bearing
a male sexual organ.

Anaerobiotic. Organisms which can
vegetate without a supply of free oxygen
are anaerobiotic. Comp. aerobiotic.

Angiocarpous. Having a hymenium
developed by internal differentiation
within the sporophore and from the
first covered by a special envelope.
Comp. gymnocarpous.

Annulus. In Hymenomycetes : portion of
ruptured marginal veil or of tissue of the
stipeforming a collar orfrill or sheath upon
the stipe after the expansion of the pileus.
Frequently used to designate the special
form distinguished as annulus inferus.
Same as ring.

492

Annulus inferus. In Hymenomycetes:
collar attached to the stipe below the
apex formed by rupture of marginal veil
round the margin of the pileus. See
annulus.

Annulus mobilis. In Hymenomycetes:
portion of ruptured marginal veil re-
maining as a moveable annular sheath
upon the stipe after expansion of the
pileus. See annulus.

Annulus superus. In Hymenomycetes :
same as armilla.

Anther. In Hymenomycetes: old term
for cystidium.
Antheridium. (a) Male sexual organ.

(6) In Hymenomycetes: old term for
_ eystidium.

Anthrax. Disease in animals and man
excited by Bacillus Anthracis.

Aphthae. Same as thrush.

Apogamy. Loss of sexual function without
suppression of the normal product of the
sexual act.

Apothecium. Same as discocarp.

Appendicula. In Erysipheae: branching
hair-like process at the summit of sporo-
carp.

Archegonium. Female sexual organ with
narrow upper portion (neck) pierced by
a canal usually enclosing one or more
cells (neck-canal-cells) and leading to a
basal dilated portion (venter) containing
one oosphere (ovum) and a smaller cell
at the entrance of the neck-canal (ventral
canal-cell). After fertilisation the embryo
is developed within the venter. }

Archicarp. Beginning of a fructification,
i.e. cell or group of cells fertilised by a
sexual act. Same as ascogonium, carpo-

gonium.

Areolate. Marked out into small areas or
spaces.

Armilla. In Hymenomycetes: plaited

frill suspended from apex of stipe formed
by a layer of tissue separated from the
surface of the stipe except at apex, and
forming at first a covering membrane of
the hymenium, from which it is detached
on expansion of the pileus. Same as
annulus superus, frill.

Arthrosporous. In Schizomycetes : spe-
cies which have no endogenous spore-
formation are arthrosporous.

Asciferous. Bearing asci.

Ascocarp. In Ascomycetes: sporocarp
producing asci and ascospores ; its three
kinds are apothecium or discocarp, peri-
thecium or pyrenocarp, and cleistocarp.

Ascogenous. Producing asci.

Ascogonium. In Ascomycetes:
as archicarp.

Ascophore. Sporophore bearing an ascus.
See sporophore.

same

EXPLANATION OF TERMS.

Ascospore. Spore formed in an ascus.
Same as thecaspore.

Ascus. In Ascomycetes : large cell, usually
the swollen extremity of a hyphal branch,
in the ascocarp within which spores
(typically 8) are developed. Same as
theca,

Ascus-apparatus. In Ascomycetes :
portion of the sporocarp consisting of
the asci together with the ascogenous
cells.

Ascus suffultorius.
basidium.

Autoecious. A parasite which goes through
the whole course of its development on a
single host of a particular species is
autoecious. Same as autoxenous.
Comp. metoecious, lipoxenous.

Autoxenous. Same as autoecious.

Axile. In the axis of any structure.

Azygospore. In Mucorini: apogamously
formed spore resembling a zygospore.

Corda’s term for

Basidiogenetic. Produced upon a basi-
dium.

Basidiophore. Sporophore bearing a
basidium. See sporophore.

Basidiospore. Spore acrogenously ab-
jointed upon a basidium.

Basidium. Mother-cell from which spores
are acrogenously abjointed. Same as
ascus suffultorius, sterigma.

Basipetal. In the direction of the base.
Comp. acropetal.

Basiscopie. Looking towards the base,
i.e. on the sidetowards the base. Comp.
acroscopic.

Bion. An individual morphologically and
physiologically independent.

Blastema. Wallroth’s term for the lichen-
thallus.

Brood-bud. (a) In Lichens: same as
soredium. (4) In Archegoniatae : same
as bulbil. 3

Brood-cell. Propagative cell, naked or
with a membrane, produced asexually,
separating from the parent and capable of
developing directly into a new bion.
Same as gonidium, conidium. Itpasses
without demarcation into the brood-
gemma and bulbil.

Brood-gemma. Pluricellular propagative
body without differentiation, produced
asexually, separating from the parent
and capable of developing directly into a
new bion. Same as gemma. It passes
without demarcation into the brood-cell
on the one side, and into the bulbil on
the other.

Bulbil. (a) In some Fungi doubtfully
considered Ascomycetes: small pluri-
cellular bodies incapable of germination.
(6) In Archegoniatae: deciduous leaf-

EXPLANATION OF TERMS.

bud capable of developing directly into a
new bion. Same as brood-bud.

Bulbus. In Hymenomycetes: swollen
base of the stipe of the sporophore.

Canker. Disease in deciduous-leaved trees
caused by Nectria ditissima, Tul. and
characterised by malformation of the rind,
exhibiting a swollen cushion-like margin
and a depressed dead centre.

Cap. In Hymenomycetes : same as pileus.

Capillitium. Sterile thread-like tubes or
fibres, often branched or combined in a
net, interpenetrating the mass of spores
within a ripe sporogenous body.

Capitate. Having the form of a head.

Carpogonium. Same as archicarp.

Carpophore. Stalk of a sporocarp.

Carpospore. Spore formed in a sporocarp.

Cellular spore. Same as sporidesm.

Cementation (Verklebung) of hyphae.
Union of membranes by a narrow slip of
cementing substance, so that hyphae are
inseparably grown together. Same as
concrescence.

Cephalodium. Peculiarly shaped bran-
ched or convex outgrowth of a lichen-
thallus in which algal cells are localised.

Chain-gemma. In Mucoreae: gemma
having the form of a septate confervoid
filament, the segments of which are
capable of sprouting. Same as sprout-
gemma.

Chlamydospore.
spore-membrane.

Chromidium. Term proposed by Stitzen-
berger for an algal cell in a lichen-thallus.
See gonidium.

Clamp-cell. See clamp-connection.

Clamp-connection (Schnallen-verbind-
ung). Small semicircular hollow protu-
berance attached laterally along its whole
length (or leaving an eye-hole) to the walls
of two adjoining cells of a septate hypha
and stretching over the septum between
them, either communicating with one or
both cells of the hypha or completely
delimited from both and then forming a
clamp-cell (Schnallen-zelle).

Cleistocarp. Ascocarp in which the asci
and ascospores are formed inside a com-
pletely closed envelope from which the
ascospores escape by its final rupture.

Coalescence (Verschmelzung) of hy-
phae. Complete fusion of the mem-
branes of two originally separate hyphae
or hyphal branches.

Cochleariform. Spoonshaped.

Collenchyma. Form of thick-walled
parenchyma in which the middle of the
lateral walls of the prismatic cells are
thin but the angles strongly thickened so
as to round off the cavity of the cell.

Spore with a very thick

493

Columella. Sterile axile body within a
sporangium.

Compound Fungus-body (zusammen-
gesetzter Pilzkörper). Growth-form in
which the thallus is constituted by the
cohering of the ramifications of separate
hyphae. Comp. Filamentous Fungus,
Sprouting Fungus.

Compound spore. Same as sporidesm.

Compound sporophore (Fruchtkörper).
Sporophore formed by the cohesion of
the ramifications of separate hyphal
branches. Comp. simple sporophore.

Concatenate. Linked together in a chain.

Conceptacle. General expression for a
superficial cavity opening outwards
within which gonidia are produced.

Concrescence. Same as cementation.

Conidiophore. Same as gonidiophore.

Conidium. Same as brood-cell.

Conjugation. Union of two gametes to
form a zygote.

Conjugation-cell. Same as gamete.

Cortex. Same as rind.

Cortina. In Hymenomycetes: marginal
veil ruptured at its connection with the
stipe and hanging from the margin of the
pileus as a shreddy membrane. Same as
curtain, velum in narrower sense of
Persoon.

Cross-septation (Querzergliederung).
Division of the terminal portion of a
hypha or hyphal branch by transverse
septa into a number of spore-cells.

Crustaceous thallus(thalluscrustaceus).
In Lichens: a thallus is crustaceous when
it forms aflatcrust on or in thesubstratum,
adhering firmly to this by its whole under
surface, so that it cannot be separated
without injury. Same as thallus lepodes.

Crystalloid. Crystal of proteid.

Cup. In Ascomycetes: same as discocarp.

Curtain. Same as cortina.

Cutis. Same as pellicula.

Cyphella. In Lichens: circumscribed pit
in the rind on the under surface of the
thallus.

Cystidium. In Hymenomycetes: large
unicellular; often inflated, structure pro-
jecting beyond the basidia and para-
physes of the hymenium. See anther,
antheridium, pollinarium,

Dichotomy. Forking in pairs, i.e. cessation
of previous increase in length at an apex
with continuation equallyin two diverging
directions, Comp. monopodium,

Diclinous. Having male or female sexual
organs developed on different branches
of a thallus. Comp. androgynous.

Dioecious. Having male and female organs
on different individuals. Comp.monoe-
cious.

494

Discocarp. In Ascomycetes: ascocarp in
which the hymenium lies exposed whilst
the asci are maturing. Same as apothe-
cium, cup.

Discus. Hymenium of a discocarp. Same
as lamina proligera, lamina sporigera.

Dissepiment. Same as trama.

Dorsiventral. Horizontally extended so as
to have a dorsal and a ventral surface.

Ectosporous. Having exogenously formed
spores. See exosporous. Comp. endo-
sporous.

Ejaculation of spores.
of spores.

Ejeetion (Ausschleuderung) of spores.
Throwing out with force of endogenously
formed spores from a sporangium. Same
as ejaculation of spores.

Elater. In Myxomycetes: a free capillitium
thread.

Encarpium. Trattinick’s term for sporo-
phore.

Endogenous. Produced inside another
body. Comp. exogenous. j

Endogonidium. Gonidium formed within
a receptacle (gonidangium).

Eindophyte. Plant growing inside another
plant and parasitic uponit or not parasitic.
Comp. epiphyte.

Endosporium. Innermost coat of a spore.
Comp. exosporium, episporium.

Endosporous. Having endogenously
formed spores. Comp. exosporous,
ectosporous.

Entozoie. Living inside an animal.

Envelope-apparatus. In Ascomycetes:
all the parts of the sporocarp except the
ascus-apparatus which consists of asci
and the ascogenous cells.

Epinasty. That state of a growing dorsi-
ventral organ in which the dorsal surface
grows more actively than the ventral
surface. Comp. hyponasty.

Epiphloeodie. Of Lichens: living upon
the surface of the periderm of a plant.
Comp. hypophloeodic.

Epiphragm. In Nidularieae: delicate
membrane closing the cup-like sporo-
phore.

Epiphyte. Plant growing upon the outside
of another plant and either not parasitic
upon it or parasitic. Comp. endo-
phyte.

Epiplasm. Same as glycogen-mass.

Episporium. Outer (second) coat of spore.
See exosporium. Comp. endosporium.

Ergotised. Attacked by ergot.

Excipulum. Outer envelope of a disco-
carp developed as part of the envelope-
apparatus.

Exogenous. Produced -on the outside of
another body. Comp. endogenous.

Same as ejection

EXPLANATION OF TERMS,

Exosporium. (a) Same as episporium.
(4) In Peronosporeae: thick coat de-
veloped from periplasm around the 0o-
spore.

Exosporous. Having exogenously formed
spores. Comp. endosporous.

Extracellular. Outside of a cell.
intracellular.

Extramatrical. Outside of a matrix or
nidus. Comp. intramatrical.

Comp.

Facultative. Occasional, incidental. Comp.
obligate.

Facultative parasite. An organism which
can and normally does go through the
whole course of its development as a
saprophyte, but which may also go
through its development wholly or in
part as a parasite. Comp. obligate
parasite, facultative saprophyte.

Facultative saprophyte. An organism
which normally goes through the whole
course of its development as a parasite,
but which can at certain stages vegetate
as asaprophyte. Comp. obligate para-
site, facultative parasite.

Favus. Disease of the skin caused by
Achorion Schönleinii, Remak.

Felted tissue. Same as tela contexta.

Fertilisation-tube. In Peronosporeae:
tube put out by the antheridium which
pierces the oogonium and is the channel
through which gonoplasm passes from the
antheridium to the oosphere.

Fibrillose. Having a finely lined appear-
ance as if composed of fine fibres.

Fibrillose mycelium. Same as fibrous
mycelium.

Fibrous mycelium. Mycelium in which
the hyphae form by their union elongated
branching strands (mycelial strands).
Same as fibrillose mycelium. Comp.
filamentous mycelium, membranous
mycelium.

Filamentous Fungus (Fadenpilz).
Growth-form in which the thallus is con-
stituted by a branched hypha alone, i.e.
without union with other hyphae. Comp.
Compound Fungus-body, Sprouting
Fungus.

Filamentous mycelium. Mycelium of
free hyphae which are at most loosely
interwoven with one another, but without
forming bodies of definite shape and out-
line. Same as floccose mycelium.
Comp. fibrous mycelium, membran-
ous mycelium. j

Filamentous sporophore. Same as sim-
ple sporophore.

Filamentous thallus (thallus filamen-
tosus). Same as fruticose thallus.

Flabelliform. Spread out like a fan.

Flacherie. Disease of the silkworm due to

EXPLANATION OF TERMS.

fermentation of food in intestinal canal
caused by Micrococcus Bombycis, Cohn.

Flagellum. (a) Solitary long swinging
process of the protoplasmof a swarmspore.
(4) Long whip-like process on the cells of
some Schizomycetes.

Floccose mycelium. Same asfilamentous
mycelium.

Foliaceous thallus (thallus foliaceus).
In Lichens: a flat, leaf-like, usually lobed
and crisped thallus which spreads over
the surface of the substratum, but is only
attached at one or several scattered

oints andcan be separated thereforefrom
it without much injury. Same as frondose
thallus (thallus frondosus), thallus
placodes.

Form-genus. A genus constituted by
similar form-species.

Form-species. Species constituted by a
single stage of the life-cycle of a pleo-
morphous species and supposed of itself to
be the complete representative of a
species.

Formae oxydatae. In Lichens: crusta-
ceous forms which have acquired a rust-
colour owing to infiltration of a salt of iron.

Frill. Same as armilla.

Frondose thallus (thallus frondosus).
Same as foliaceous thallus.

Fructification. Unicellular or pluricellular
body developed as a result of the sexual
act from an archicarp alone or from
adjacent hyphae as well. In the uni-
cellular form it is a zygospore or oo-
spore ; in the pluricellular form a sporo-

carp.

Fruticose thallus (thallus fruticulosus).
In Lichens: a thallus attached by one
point only and by a narrow base to
the substratum from which it grows
upwards as a simple or more usually
branched shrub-like body. Same as fila-
mentous thallus, thallus thamnodes.

Fuliginosus. Sooty.

Funiculus.. In Nidularieae: cord of
hyphae attaching peridiolum to the inner
surface of the wall of the peridium.

Gamete. Sexual protoplasmic body, naked
or invested with a membrane, motile
(zoogamete or planogamete) or non-
motile, which on conjugation with another
gamete of like or unlike outward form
gives rise to a body termed zygote. Same
as conjugation-cell.

Gattine. Same as pébrine.

Gelatinous felt (Gallertfilz).
gelatinous tissue.

Gelatinous tissue (Gallertgewebe). Tis-
sue which is slimy owing to the cell
membranes being soft and mucila-
ginous. Same as gelatinous felt.

Same as

495

Gemma. Same as brood-gemma.

Germ-cell. First product of commencing
germination of a spore.

Germ-tube (Keimschlauch). Tubular
process put out by a spore in tube-ger-
mination at one or more points of its
surface which by continued progressive
apical growth developes into a hypha
forming either a promycelium or a
mycelium.

Germ-pore. Pit on the surface of a spore-
membrane through which a germ-tube
makes exit.

Gill. Same as lamella.

Gleba. Chambered sporogenous tissue
within a sporophore.

Glycogen-mass. Protoplasm permeated
with glycogen, especially in asci. Same
as epiplasm. Sometimes shortly termed:
glycogen.

Gonidiallayer. (a) Aggregation of simple
gonidiophores to form a cushion-like
layer or crust. (4) In heteromerous
Lichens : same as algal layer.

Gonidiophore Sporophore bearing a
gonidium. Same as conidiophore. See
sporophore.

Gonidium. (a) Same as brood-cell. (4) In
Lichens: algal cell of thallus. Same as
chromidium.

Gonimic layer. Same as algal layer.

Gonoplasm. In Peronosporeae: portion
of protoplasm of antheridium which
passes through the fertilisation-tube and
coalesces with the oosphere. Comp.
periplasm.

Green-rot. Disease in wood characterised
by the tissues becoming a verdigris green.
Peziza aeruginosa, Pers., is commonly
associated with this condition, but its
connection with the prominent feature
of the disease is still uncertain.

Growth-form. A vegetative structure
marked by some easily recognised fea-
ture of growth characterising individuals
or stages in the life-cycles of types which
have no necessary genetic affinity. Thus
Sprouting Fungus, Filamentous Fungus,
&c. are growth-forms.

Gymnocarpous. Having the hymenium
exposed when the spores are maturing.
Comp. angiocarpous.

Gynandrosporous. In Oedogonieae : dioe-
cious forms in which the female plant
produces androspores are gynandro-
sporous.

Haustorium. Special branch of a fila-
mentous mycelium serving as an organ
of attachment and suction.

Heliotropism. Phenomena induced in a
growing organ by the influence of illumi-
nation.

496

Herpes tonsurans. Same as ring-worm.

Heteroecious. Same as metoecious.

Heteromerous. In Lichens: a thallus
with stratified tissue owing to algal cells
forming an algal layer and dividing the
hyphal tissue into an outer (rind) and an
inner (medullary) stratum is termed
heteromerous. Comp. homoiomerous.

Heterosporous. Having asexually pro-
duced spores of more than one kind.
Comp. homosporous.

Homoiomerous. In Lichens: a thallus
with algal cells and hyphae distributed
uniformly and in about equal proportion
is termed homoiomerous. Comp. heter-
omerous.

Homologous. Having the same position
and development.

Homosporous. Having asexually pro-
duced spores of only one kind. Same as
isosporous. Comp. heterosporous.

Hydrotropism. Phenomena induced in
a growing organ by the influence of
moisture.

Hymenial Alga. In Lichens: algal cell
in a sporocarp. Same as hymenial
gonidium,

Hymenial gonidium. Same as hymenial
Alga.

Hymenial layer. Same as hymenium.

Hymenium, Aggregation of spore-mother-
cells, with or without sterile cells, in a
continuous stratum or layer upon a sporo-
phore. Same as sporogenous layer,
hymeniallayer. Seealso discus,lamina
proligera, lamina sporigera.

Hymenophorum. Portion of a sporo-
phore which bears a hymenium.

Hypha. The element of a thallus in
most Fungi; a cylindric thread-like
branched body consisting of a membrane
enclosing protoplasm, developing by apical
growth and usually becoming transversely
septate as it developes,

Hyponasty. That state of a growing
dorsiventral organ in which the ventral
surface grows more actively than the
dorsal surface. Comp. epinasty.

Hypophloeodic. Of Lichens: living in the
peridermofaplant. Comp. epiphloeodic.

Hypothallus. In crustaceous Lichens:
marginal outgrowth of hyphae, often
strand-like, from the thallus. Same as
protothallus.

Hypothecium. Layer of hyphal tissue
immediately beneath a hymenium. Same
as subhymenial layer.

Inception (Anlegung). First beginning.

Inner peridium. See peridium inter-
num.

Intracellular. Inside a cell. Comp. extra-
cellular.

EXPLANATION OF TERMS.

Interweaving (Verflechtung) of hyphae.
Union by interwining without firm cohe-
sion with one another.

Intralamellartissue. In Hymenomycetes:
same as trama,

Intramatrical. Inside a matrix or nidus.
Comp. extramatrical.

Involucrum. Persoon’s term for velum.

Involution-form. Swollen bladderlike
form of Schizomycete, supposed to be
a diseased condition of the form with
which it is found associated.

Involution-period. Same as resting
period.

Involution-stage. Sameas resting stage.

Isogamy. Conjugation of two gametes
of similar form. Comp. oogamy.

Isosporous. Same as homosporous.

Kernel. In. Pyrenomycetes: old term
for the whole of the softer part of the
pyrenocarp within the firm outer wall.
Also termed nucleus.

Lamella. In Hymenomycetes: vertical
radial plate on the under surface of the
pileus upon which the hymenium is
extended. Same as gill.

Lamina proligera. Same as discus.

Lamina sporigera. Same as discus.

Lipoxenous. A parasite that leaves its
host and completes its development inde-
pendently, and at the expense of reserve
of food appropriated from the host is
lipoxenous. Comp. metoecious.

Lipoxeny. Desertion of a host.

Lysigenetic. Formed by disorganisation
or dissolving of cells.

Macrogonidium. Large gonidium com-
pared with others produced by the same
species. Same as megalogonidium.
Comp. microgonidium.

Madura. Disease in man characterised
by swelling and degeneration in feet and
hands and supposed to be due to
Chionyphe Carteri, Berkl, but the
causal connection is not definitely made
out.

Malignant oedema. Disease in animals
like anthrax and due to a Bacillus in
form resembling Bacillus Anthracis.

Marginal veil. In Hymenomycetes: a
membrane stretching from the margin of
the pileus to the surface of the stipe in
the young sporophore and covering over
the hymenium. Same as velum partiale.
See velum.

Medulla. Central tissue within the rind
of a Fungus-body. In Lichens: same
as stratum medullare.

Megalogonidium. Same as macrogo-
nidium,

EXPLANATION OF TERMS.

Membranous layer.
branous mycelium.

Membranous mycelium. Mycelium in
which the hyphae form by interweaving
a membranous layer. Same as mem-
branous layer, myceliallayer. Comp.
filamentous mycelium, membranous
mycelium.

Mentagra parasitica. Same as sycosis.

Merispore. Segment of a sporidesm.

Meristem. Actively dividing cell-tissue.

Meristematic. Consisting of meristem.

Meristogenetic. Produced bya meristem.

Metabolism. The chemical processes
inseparably associated with the vital
activity of protoplasm.

Metoecious. Forms which pass through
separate sections of their complete de-
velopment upon different hosts are me-
toecious. Same as metoxenous, hete-
roecious. Comp. autoecious, lipo-
xenous.

Metoxenous. Same as metoecious.

Microcyst. In Myxomycetes: a resting
state of the swarmcells.

Microgonidium. Small gonidium com-
pared with others produced by the same
species. Comp. macrogonidium.

Micropylar. Belonging to the micropyle.

Microsoma. Small granule embedded
in the hyaline plasm of protoplasm and
constituting an essential portion of its
substance.

Monoecious. Having male and female
organs on the same individual. Comp.
dioecious.

Monopodium. An axis of growth which
continues to grow at the apex in the
direction of previous growth, while lateral
structures of like kind are produced
beneath it in acropetal succession. Comp.
dichotomy, sympodium.

Multilocular spore. Same as sporidesm.

Muscardine. Disease of the silkworm
caused by Botrytis Bassii.

Mutualism. Symbiosis in which two
organisms living together mutually and
permanently help and support one an-
other.

Mycelial layer.
mycelium.

Mycelial strand: See fibrous mycelium.

Mycelium. Vegetative portion of thallus of
Fungi composed of one or more hyphae.

Mycetogenetic. Produced by Fungi.

Mycetogenetic metamorphosis. Defor-
mation of parts due to Fungi.

Mycosis. A disease of animal tissues due
to the vegetative activity of species of
Eurotium.

Myxamoebae. In Mycetozoa: swarm-
cells with purely amoeboid creeping
motion,

[4]

Same as mem-

Same as membranous

497

Neck. In Pyrenomycetes: conical or
cylindrical prolonged apex of pyrenocarp
through which runs the canal leading to
the ostiole. Same as tubulus.

Nucleus. See kernel.

Obligate. Necessary, essential. Comp.
facultative.

Obligate parasite. An organism to which
a parasitic life is indispensable for the
attainment ofits full development. Comp,
facultative saprophyte, facultative
parasite.

Ontogeny. Development of an individual.

Oogamy. Conjugation of two gametes of
dissimilar form. Comp. isogamy.

Oogonium. Female sexual organ usually
a more or Jess spherical sac, without the
differentiation into neck and venter of
archegonium, and containing one or
more oospheres (ova). The oospore does
not divide to form a proembryo within
the cavity of the oogonium on the parent
plant.

Oosphere (egg, ovum). Naked nucleated
spherical or ovoid mass of protoplasm
which, after its nucleus has coalesced
with the sperm nucleus, developes the
oospore.

Oospore. Immediate product of fertilisa-
tion in oosphere.

Ostiole (ostiolum). In Pyrenomycetes:
aperture in pyrenocarp through which
discharge of spores takes place. Same
as pore.

Outer peridium. See peridium exter-
num.

Ovule. In Phanerogams: macrosporan-
gium.
Panicle. Twice or more branched struc-

ture in which the base of each branching
is elongated.

Paniculate. Having the form of a panicle.

Paraphyses-envelope. In Uredineae:
same as peridium.

Paraphysis. Sterile capilliform hyphal
branch accompanying spore-mother-
cellsina hymenium. Applied by Phoebus
especially to a cystidium.

Parasite. Organism living on or in and
at the expense of another living organism
(host). Comp. saprophyte.

Parthenogenesis. Form of apogamy in
which the oosphere (ovum) itself de-
velopes into the normal product of
fertilisation without a preceding sexual
act.

Pathogenous. Producing disease.

Pébrine. Disease of the silkworm
caused by Nosema Bombycis, Nag.,
a bacterioid organism. Same as gat-
tine.

kk

498

Pellicula. Theseparablerind-layersofsome
compound sporophores. Same as cutis.

Penicellate. Having the form of a pencil
of hairs.

Periderm. The cork-cambium and its
products.

Peridiolum. In Nidularieae: chamber
of the gleba, forming a nest of spores,
free or attached by a funicle within the
peridium of the sporophore.

Peridium. General term for the outer en-
veloping coat of a sporophore upon which
the spores develope in a closed cavity.
InUredineaeit envelopestheaecidium and
is also termed pseudoperidium, para-
physes-envelope. In Gastromycetes
termed also uterus, and may be differen-
tiated into peridium externum (outer
peridium), the outermost layer which
opens in various ways and separates from
the peridium internum (inner peri-
dium)a layer directly enclosing the gleba.

Peridium externum. See peridium.

Peridium internum. See peridium.

Periphysis. In Pyrenomycetes: sterile
capilliform hyphal branch projecting
from the wall of the pyrenocarp where
there is no hymenium into its cavity.

Periplasm. In Peronosporeae: protoplasm
in the oogonium and the antheridium
which does not share in the conjugation.
Comp. gonoplasm.

Perithecium. Same as pyrenocarp.

Phototactic. Taking up a definite position
with reference to the direction of incident

rays of light.

Phylogeny. Development of a species or
larger group.

Pileus. In Hymenomycetes: primarily,

the conical or dome-shaped upper portion
of the compound sporophore bearing a
hymenium on its under side; now ex-
tended to all compound sporophores
in which the hymenium looks to the
ground. Same as cap.

Pityriasis versicolor. Disease of the
skin caused by Microsporon furfur, Rob.

Plasmodium. In Mycetozoa: body of
naked plurinucleated protoplasm exhi-
biting amoeboid motion.

Plasmatoparous. In Peronosporeae :
forms are plasmatoparous when in ger-
mination the whole protoplasm of a goni-
dium issues as a spherical mass which at
once becomes invested with a membrane
and then puts out a germ tube.

Plastid. Small variously shaped portion
of protoplasm of a cell differentiated
as a centre of chemical activity.

Pleomorphism or Pleomorphy. The
occurrence of more than one independent
form in the life cycle of a species.

Pleuroblastic. In Peronosporeae: forms

EXPLANATION OF TERMS.

producing vesicular lateral outgrowths
serving as haustoria are pleuroblastic.
Pluricellular. Composed of two or more
cells.
Plurisporous. Having two or more spores.
Podetium. In Cladonieae: stalk-like or
shrubby branched outgrowth of the
thallus bearing exposed hymenia.
Pollinarium, Same as cystidium.
Pore. (a)In Pyrenomycetes: sameas ostiole.
(6)In Hymenomycetes : same as tubulus.
Primary lamella of spore. Outermost
layer of the coats of a spore representing
the original delicate wall of the primordial
spore.
Primordium,
structure.
Procarp. An archicarp with a special
receptive apparatus, the trichogyne.
Promycelium. Short and short-lived
product of tube-germination of a spore
which abjoints acrogenously a small
number of spores (sporidia) unlike the
mother-spore and then dies oft.
Prosporangium. In Chytridieae: vesi-
cular cell the protoplasm of which passes
into an outgrowth of itself, the sporan-
gium, and becomes divided into swarm-

First beginning of any

spores.

Prothallium. A thalloid oophyte or its
homologue.

Protothallus. Same as hypothallus.

Pseudoparenchyma. Symphyogenetic

cellular tissue.

Pseudoperidium. See peridium.

Pseudopodium. In Mycetozoa: a pro-
trusion of the protoplasm of an amoeboid
body which may be drawn in or into which
the whole mass may move.

Puffing (stäuben). Sudden discharging of
a cloud of spores.

Pullulation. Same as sprouting.

Pulvinate. Having the form of a cushion.

Pycnidiophore. Compound sporophore
bearing pycnidia.

Pyenidium. In Ascomycetes: a variously
shaped cavity resembling a pyrenocarp
formed on the free surface of a thallus
and containing gonidia which are termed
pycnogonidia. See receptaculum.

Pyenogonidium. Gonidium produced in
a pycnidium. Same as pycnospore,
stylospore.

Pyenospore. Same as pyenogonidium.

Pyrenocarp. Cup-shaped ascocarp with
the margin incurved so as to form a
narrow-mouthed cavity. Same as peri-
thecium.

Receptacle (receptaculum). Term of
varying signification, most usually imply-
ing a hollowed-out body containing other
bodies. Has the following special appli-

EXPLANATION OF TERMS.

cations in this book :—(a) Leveillé’s term
for sporophore. (4) Same as stroma.
(c) In Ascomycetes : stalk of a discocarp.
(a) In Ascomycetes: same as pyenidium.
e) In Phalloideae: inner portion of
sporophore supporting the gleba. (/) In
Lichens: cup of the thallus containing
soredia.

Rejuvenescence. Transformation of whole
of protoplasm of a previously existing cell
into a cell of a different character.

Resin-flux (Harzsticke, Harzüberfülle).
Disease in conifer characterised by
copious flow of resin with ultimate death
of the tree, due to attack of Agaricus
melleus.

Resting period. Period during which a
dormant or quiescent state is exhibited.
Same as involution-period.

Resting-stage. Stage of dormancy or
quiescence. Same as involution-stage.

Resting state. Quiescent or dormant
condition.

Rheotropism. Phenomena induced in a
growing organ by the influence of a cur-
rent of water.

Rhizine. Same as rhizoid.

Rhizoid. Delicate filiform or hair-like
organ of attachment. Same as rhizine.

Rhizomorphous. Having delicate branch-
ing form like rootlets.

Rind. (a) The outer layer or layers of a
Fungus-body. Same as cortex. In
Lichens: same as stratum corticale.
(5) The outer layers of the bark in a
tree with secondary thickening and some-
times all the tissue outside the active
phloem.

Ring. Same as annulus.

Ringworm. Disease of the skin due to
Trichophyton tonsurans, Malmsten.
Same as tinea tonsurans, herpes ton-
surans.

Rudimentary (rudimentär). An organ
or member is rudimentary which remains
stationary at a stage of development in
which it is in every respect immature.

Saprophyte. Plant living on dead organic
substance. Comp. parasite.

Schizogenetic. Formed by separation of
tissue elements owing to splitting of the
common wall of cells.

Sclerosed. Exhibiting sclerosis.

Sclerosis. Induration of a tissue or a cell-
wall either by thickening of the mem-
branes or by their lignification, i.e. for-
mation of lignin in them.

Sclerotioid. Resembling a sclerotium.

Sclerotium. Pluricellular tuber-like reser-
voir of reserve material forming on a
primary filamentous mycelium from which
it becomes detached when its develop-

499

ment is complete, usually remains dormant
for a time, and ultimately produces shoots
which develope into sporophores at the
expense of the reserve material. In
Mycetozoa the sclerotium is formed out of
a plasmodium and after its period of
rest developes a plasmodium again.

Secondary mycelium. Rhizoid attach-
ments developed from the base of a
sporophore which are somewhat like the
normal mycelium of the species.

Semen multiplex. Tulasne’s term for
sporidesm.

Septate spore. Same as sporidesm.

Simple sporophore (Fruchthyphe,
Fruchtfaden). Sporophore consisting
of a single hypha or branch ofa hypha
Same as filamentous sporophore
Comp. compound sporophore.

Soredial branch. Branch produced by
the development of a soredium into a new
thallus while still on the mother-thallus.

Soredium. In Lichens: single algal cell or
group of algal cells wrapt in hyphal tissue,
which, when set free from the thallus, is
able at once to grow into a new thallus.
Same as brood-bud.

Soredium-heap. Same as sorus.

Sorus. Heap or aggregation. (ae) In
Synchitrieae: heap of sporangia devel-
oped from a swarmcell. (6) In Lichens :
heap of soredia forming a powdery mass
on the surface of thallus.

Spermatiophore. Structure bearing a sper-
matium.

Spermatium. Male non-motile gamete-
cell which conjugates with a trichogyne.
The male sexual function of all spermatia
is not yet demonstrated.

Spermatozoid. Male motile gamete.

Spermogonium. Receptacle in which
spermatia are abjointed.

Spora cellulosa. Same as sporidesm.

Spora composita. Same as sporidesm.

Spora multilocularis. Same as spori-
desm.

Sporangiolum. In Mucorini: small
sporangium produced in some genera in
addition to the large sporangium.

Sporangiophore, Sporophore bearing a
sporangium. See sporophore.

Sporangium. Sac producing spores endo-
genously.

Spore. Single cell which becomes free and
is capable of developing directly into a
new bion.

Spore-group. Same as sporidesm.

Spore-plasm. Protoplasm of a sporangium
devoted to the formation of spores.

Sporidesm. Pluricellular body becoming
free like a spore and in which each cell is
an independent spore with power of ger-
mination. Same as spore group, com-

Kok 2

500

pound spore, spora composita, septate
spore, semen multiplex, multilocular
spore (spora multilocularis), cellular
spore (spora cellulosa), pluricellular
spore.

Sporidium. Spore abjointed on a promy-
celium.

Sporiferous. Bearing spores.

Sporoblast. Körber’s term foramerispore.

Sporocarp (sporocarpium). Pluricellular
fructification, i.e. pluricellular body de-
veloped as the result of the sexual act
from an archicarp alone or from adjacent
hyphae as well, unlike the body which
produced the archicarp, and essentially
serving to the formation of spores. See
fructification.

Sporogenous. Producing spores.

Sporogenouslayer. Same as hymenium.

Sporophore (Fruchtträger). Branch or
portion of thallus which bears spores or
spore-mother-cells. Same as recepta-
culum of Leveillé, encarpium of
Trattinick. Its forms are distinguished
as gonidiophore, sporangiophore, ba-
sidiophore, ascophore, &c.

Sporophyte. In Archegoniatae: the seg-
ment in the life-cycle which produces
spores.

Sporula. Old term for what is designated
above as spore.

Sprout-cell. Cell produced by sprouting.

Sprout-chain. Chain of cells produced by
sprouting.

Sprout-gemma.
as chain-gemma.

Sprout-germination (Sprosskeimung).
Germination of a spore in which a small
process (germ-cell), with a narrow base,
protrudes at one or more points on the
surface of the spore, then assumes an
elongated cylindrica] form, and finally is
abjointed as a sprout-cell. Comp. tube-
germination.

Sprouting. Formation of an excrescence
with a narrow base, and of the same
character as the parent, at one or more
points on a cell, which after enlargement
is delimited by a transverse wall either
before or after reaching its proper size.
Same as pullulation.

Sprouting-fungus (Sprosspilz). Growth-
form in which the thallus consists of a
sprouting-cell or chain of sprouts, Comp.

In Mucoreae: same

Filamentous Fungus, Compound
Fungus-body. |
Sterigma. (a) Same as basidium. (2)

Stalk-likebranch of a basidium bearing a

spore. (c) Cell from which a spermatium
is abjointed.

Sterile basidium. In Hymenomycetes:

body in the hymenium like a basidium but

- non-sporiferous and possiblya paraphysis.

EXPLANATION OF TERMS.

Stipe (stipes). General term for the stalk
of a sporophore.

Strand. See mycelial strand.

Stratum corticale. See rind.

Stratum gonimon. Same as algal
layer.
Stratum medullare. See medulla.

Stroma. Compound Fungus-body having
the form of a cushion, crust, foliaceous ex-
pansion, or erect unbranched or branched
shrub-like body. Same as receptaculum.

Stylospore. Same as pyenogonidium.

Suberification. Same as suberisation.

Suberisation. Transformation of a cell-
wall into suberin, i.e. conversion into
cork. Same as suberification.

Subhymenial layer. Same as hypo-
thecium. .

Subulate. Awl-shaped.

Suspensor. In Mucorini ; club-shaped or
conical portion of hypha adjoining a
gamete-cell after its delimitation. Same
as zygosporophore.

Swarmcell. Motile naked protoplasmic
body.

Sycosis. Disease of the skin due to the at-
tack of Microsporon Audouini, Rob., and
Microsporon mentagrophytes, Rob. Same
as mentagra parasitica.

Symbion. Organism which lives in a state

of symbiosis.

Symbiosis. Living together of dissimilar
organisms.

Symphyogenetic. Formed by union of

previously separate elements.
Sympodial. Ofthenature of a sympodium.
Sympodjum. Anaxis made up of the bases
of a number of successive axes arising
as branches in succession one from the
other. Comp. monopodium,

Tela contexta (Filzgewebe). Weft of
distinct hyphae. Same as felted-tissue.

Teleutogonidium. Same as teleutospore.

Teleutospore. In Uredineae: spore formed
by abjunction on, but not separating from,
a sterigma, producing in germination,
which takes place after a resting period,
a promycelium.

Tetraspore. In Rhodophyceae: one of
the spores formed by division of a mother
cell into four parts.

Thallodic. Belonging to the thallus.

Thallus. A vegetative body without dif-
ferentiation into stem and leaf. In Fungi
is the whole body of the plant not serving
directly as an organ of reproduction.

Thallus lepodes. Same as crustaceous

thallus.

Thallus placodes. Same as foliaceous
thallus.

Thallus thamnodes, Same as fruticose
thallus.

EXPLANATION OF TERMS.

Theca. Same as ascus.

Thecaspore. Same as ascospore.

Thermotropism. Phenomena induced
in a growing organ by the influence of
conditions of temperature.

Thrush. Disease of the mucous membrane
ofmouth,throatandoesophagusinchildren
characterised by formation of pustules
due to Saccharomyces albicans, Reess.
Same as aphthae.

Tinea tonsurans. Same as ringworm.

Torulose. Swollen at intervals.

Trama. In Basidiomycetes: middle tissue
in the projections or septa of the sporo-
phore which bear hymenium. Same as
dissepiment, intralamellar tissue.

Tremelloid. Resembling Tremella.

Trichogyne. Thread-like receptive portion
developed as part of an archicarp.

Trophoplast. Same as plastid.

Trophotropism. Phenomena induced in
a growing organ by the influence of the
chemical nature of its environment.

Tube-germination (Schlauchkeimung).
Germination of a spore in which the first
product is a germ-tube. Comp. sprout-
germination.

Tubulus. (a) In Pyrenomycetes : Same as
neck. (4) In Hymenomycetes: tube
lined with hymenium on the surface of a
pileus. Same as pore.

Unicellular. Formed of one cell.

Uredo. Hymenium producing uredospores
only. Termed also uredo-layer.

Uredogonidium. Same as uredospore.

Uredospore. In Uredineae : spore formed
by acrogenous abjunction on a sterigma
from which it separates when mature and
on germination produces a mycelium
bearing uredospores or uredospores and
teleutospores.

Uterus. In Gastromycetes: same as peri-
dium,

Veil. Same as velum.

Veines aériféres. Same as venae in-
ternae.

Veines aquiféres. Same as venae ex-
ternae.

Velum. In Hymenomycetes: special

envelope within which the growth of the
whole or a portion of the sporophore
takes place. Same as veil, involucrum
of Persoon. By Persoon applied to what

501

is defined above as cortina. See
marginal veil, velum universale.

Velum partiale. Same as marginal
veil. See velum.

Velum universale. In Hymenomycetes
sac enclosing the whole of a sporophore
as it grows and ultimately ruptured atthe
apex by the unfolding pileus. Same as
volva. See velum.

Venae externae. In Tuberaceae: white
veins seen on section of the sporophore
produced by dense tissue containing air
and filling the asciferous chambers.
Same as veines aériféres. Comp.
venae internae. £

Venae internae. In Tuberaceae: dark-
coloured veins seen on section of the
sporophore indicating the walls of as-
ciferous chambers, which are composed
of tissue containing no air. Same as
venae lymphaticae, veines aquiféres.
Comp. venae externae.

Venae lymphaticae. Same as venae
internae.

Volva. Same as velum universale,

Witches’ broom. Disease on the silver-fir,
birch, cherry,and other trees characterised
by the development of a tangle of shoots
in a tuft and due to the attack of Peri-
dermium elatinum or of Exoascus.

Woronin’s hypha. In Ascomycetes: a
coiled hypha found in some forms at the
place where the sporocarp subsequently
developes and probably homologous with
an archicarp.

Xyloma. Sclerotioid body of varying
shape which does not send out branches
developing into sporophores but produces
sporogenous structures in its interior.

Yeast-fungus. Species of Saccharomyces.
Sometimes used as equivalent to the
growth form distinguished as Sprouting
Fungus, but this misuse leads to con-
fusion.

Zoogloea. In Schizomycetes: colony
imbedded in a gelatinous substance.

Zoospore. Motile spore.

Zygospore. Immediate product of conju-
gation of two similar gametes.

Zygosporophore. In Mucorini: same as
suspensor.

INDEX.

Names, as ‘ Acrasieae,’ ‘ Abrothallus,’ ‘Achlya Braunii,’ with no further addition, refer to the
course of development of the Orders, Genera, &c., as described in the second division of the first
part and in the second and third parts; those which are followed by some additional word, as
‘Achlya apiculata, capacity of germination,’ refer to the remaining sections of the book. An
asterisk after the number of a page indicates a Figure.

Abjection of spores, 68, 72.

Abrothallus, 416.

Abscision of spores, 68, 69.

Absidia, 147, 150, 152.

— capillata, 150.

—, discharge of spores, 83.

— septata, 150.

Acarospora, number of
spores, 79.

Achlya apiculata, capacity of
germination, 343.

— Braunii, 142, 144.

—, discharge of spores, 82.

—, formation of swarm-
spores, 143.

—, ‘pleomorphism,’ 127.

— polyandra, 142, 144.

— —, germination, 142*.

— prolifera, 144, 145.

— —, germ-plant, 141 *.

— racemosa, 144.

— —, fertilisation, 142*.

—, simple sporophores, 46.

— spinosa, 143.

— —, capacity of germina-

“ tion, 343.

—, swarm-spores, 107.

Achlyogeton, 140.

—, discharge of spores, 83.

—, swarm-spores, 107.

Achorion Schoenlinii, para-
sitism, 376.

Acolium ocellatum, discharge
of spores, 98.

Acrasieae (Acrasiea), 421,
441, 443.

Acrasis, 442.

Acrocordia gemmata, 246.

— tersa, 246.

Acrogonidia, 249.

Acroscyphus, discharge of
spores, 96.

Acrospores, 129.
Acrostalagmus cinnabarinus,
abjunction of spores, 71.
—, formation of gonidia, 65.

—, germination, III.

Acrostalagmus cinnabarinus,
mycelial strands, 22.
—, structure of spores, 103.
Actinomyces Bovis, develop-
ment and parasitism, 377.
Actinomycosis, 377.
Adaptations, different, or
metamorphosis, 256, 259.
Aecidia, 274.
—, abscision of spores, 68.
—, formation of spores, 66.
—, structure of spores, 100.
Aecidiospores, capacity of
germination, 343, 344.
Aecidium Sedi, 282.
Aethalieae (Aethaliei), 431,
434, 439.

Aethalium, 429, 431,434,439
— septicum, 424, 439, 441,
See also Fuligo varians.
Affinities of Bacteria, 474.

— of Fungi, 337, 340.

— of Mycetozoa, 442.
Agaricineae (Agaricini), 288,
289, 296, 300, 303, 338.
—, clamp-connections, 2, 19.

—, mycelial strands, 22.

—, structure of compound
sporophores, 57.

Agaricus, 301.

—, abjection of spores, 68,72.

— aeruginosus, mycelial
strands, 22, 23.
— androsaceus, mycelial

strands, 22.

— arvalis, sclerotia, 42.

— balaninus, 304.

— campestris, 291.

— —, cellulose, 8.

— —, development of sporo-
phore, 289*, 291.

— —, excretion of calcium,
11*,

— —, mycelial strands,22,23.

— —, cementation of hy-
phae, 4.

— cirrhatus, 297.

Agaricus cirrhatus, sclerotia,
32, 39, 42.

— cyathiformis, develop-
ment of sporophore, 56.

— deliciosus, 300.

—, development of sporo-
phore, 55 *.

— dryophilus, 297.

— —, development of spo-
rophore, 55 *.

— —, mycelial strands, 22.

— fumosus, 304.

— fusipes, 297.

— —, sclerotia, 42.

—, gelatinous membranes, 9,
10, 13.

— grossus, germination of
sclerotia, 40, 42.

— laccatus, 304.

— melleus, 302, 329, 341.

—-—, commencement of
sporophore, 49.

— —, development of the
veil, 290*, 291.

— —, gelatinousmembranes,
9.

— —, membranes, 12.

— —, mycelial strands, 22,
23, 24*.

— —, parasitism, 361, 384.

— metatus, cellulose-mem-
brane, 8.

— —, mycelial strands, 22.

—, mycelial strands, 22,
23.

— olearius, 301.

— platyphyllus,
strands, 22, 23.

— Pluteus, 304.

— praecox, 300.

— —,mycelial strands, 22,31.

— racemosus, 334.

— —, branching of com-
pound sporophore, 51.

— —, germination of scle-
rotia, 40

— —, sclerotia, 42.

mycelial

504

Agaricus Rotula, mycelial
strands, 22, 23.

—, sclerotia, 32.

— stercorarius, germination
of sclerotia, 40.

—, structure of sporophore,
57.

— tuberregium,sclerotia,42.

— tuberosus, 297.

— —, germination of scle-
rotia, 40.

— —, sclerotia, 32, 42.

— variabilis, 333, 334.

— velutipes, 297.

— viscidus, 304.

— volvaceus, sclerotia, 42.

— vulgaris, 334.

— —, development of sporo-
phore, 54.

— —, structure of lamellae,
301 *,

— —, structure of sporo-
phore, 57.

Aglaospora, 243.

— profusa, germination, 114.

— —, number of spores, 79.

—, number of spores, 79.

Alcoholic fermentation, 270.

Algae, course of develop-
ment, 121.

— of the Lichen-thallus, 397,
398.

— of the heteromerous
Lichen-thallus, 409.

Algal layer of the Lichen-
thallus, 404.

Algal zone of the Lichen-
thallus, 404.

Alternaria, 229, 252.

—, formation of spores, 67*.

—, spores, 68.

Alternation of bions,124,125.

— of generations, 123, 124.

Amanita, 292, 296, 297, 298,
338, 340.

—, growth of compound
sporophore, 50.

—, hyphal weft, 3.

—muscaria,292,293,298, 300.

— —, cellulose, 8.

— —, coloration of mem-
branes, Io.

— —, gelatinous membranes,

9; 13.

— phalloides, cellulose mem-
brane, 8.

—rubescens, development

of sporophore, 293*.
— vaginata, 295.
Amoebae, 443.
Amoebidium parasiticum,
- 170,
Amylobacter
455.

Clostridium,

INDEX,

Amylocarpus, 105.

Amylum, 7.

— in Bacteria, 455.

Anaptychia ciliaris, apothe-
cium, 188*, 189*,

— —, chemical properties,
407.

— —, spores, 98.

— —, structure of thallus,
404, 406.

Ancyclisteae(Ancylistei),132,
139, 170.

Ancyclistes, 139.

— Closterii, 139.

— —, parasitism, 361, 392.

Anixia truncigena, discharge
of spores, 97.

Annual layers in pilei of Poly-
poreae, 57.

— in hymenia, 307.

Annulus, 290.

— inferus, 291.

— mobilis, 292.

— superus, 295.

Antheridial branch, 198, 202,
239.

Antheridium, 202, 305.

Anthers, 305.

Anthina, 29.

— flammea, cellulose-mem-
brane, 8.

— —, mycelium, 29.

— pallida, cellulose-mem-
brane, 8.

— —, mycelium, 29.

— purpurea, cellulose-mem-

brane, 8.
— —, mycelium, 29.
Aphanocapsa in Lichen-

thallus, 398.
Aphanomyces, 143.
—, discharge of spores, 83.
—, formation ofspores,74,75.
— scaber, 142.
—, swarm-spores, 108.
Aphthae (thrush), 377.
Aplanes, 144.
— Braunii, 142.
—, capacity of germination,
343-
Apogamy, 123.
Apothecia, 187, 239, 4or.
Appendagesofspores,102,&c.
Archicarp, archicarpium, 49,
121,198, 199, 201, 238, 239.
Arcyria, 431, 434, 436, 440.
— anomala, capillitium,
spore, 437*.
— cinerea, 437, 441.
— incarnata, 434, 437.
—-—, capillitium, spore,
437*.
— nutans, 434, 437,441.
— punicea, 427,434,437,441.

Arcyria Serpula, capillitium,
spore, 437 *.

Areolation of spore-mem-
brane, 100.

Armilla (frill, annulus su-
perus), 295, 300.

Arnoldia, structure of thallus,
412,

— minutula, 413.

Arthonia epipasta, 416.

—, structure of thallus, 411.

— vuigaris, 416.

— —, origination of thallus,

399.

Arthopyrenia, 416.

Arthrobacterium, 454, 468.

— aceti, 472, 479, 481.

— merismopoedioides, 469.

— Pastorianum, 456, 472.

— Zopfii, 469.

Arthrobotrys, 252.

—, formation of spores, 64.

—, gonidia, 98.

— oligospora, simple sporo-
phores, 47 *.

—, spores, 68.

Arthrosterigmata, 240.

Artotrogus, 135, 232.

—, parasitism, 394.

Asci, 45, 60, 76, IgI, 192.

Ascobolus, 190, 198, 199, 206,
232, 235, 239.

— furfuraceus, 224.

— —, compound
phores, 186*, 207 *.

— —, conditions of germina-
tion, 350, 351.

— —, ejection of spores, 85,
92*,

— —, structure ofspores, 102.

—,conditions of germination,
350.

—, development of spores, 78.

—, ejection of spores, 85, 86.

—, germination, 111.

—, immersus, structure of
spores, 102.

—, number of spores, 79.

—, puffing, 90.

— pulcherrimus, ejection of
spores, 86.

— sexdecimsporus, 79.

—, structure of spores, 105.

Ascochyta, 252.

Ascodesmis, 186, 201, 221.

Ascogenous cells, 186.

Ascogenoushyphae, 186, 209,
214.

Ascogonium, 198, 213.

Ascomycetes, 120, 185, 285.

— as Lichen-fungi, 396.

—, capacity of germination,
348.

—, compound spores, 98.

sporo-

Ascomycetes, course of de-
velopment, 223.

—, development of sporo-
phore, 197.

—, doubtful species, 132,263.

—, envelope - apparatus of
sporocarp, 186.

—, functionless organs, 256.

—, germination, 115.

—, hairs, 59.

—, impertectly known spe-
cies, 238.

—, inception of sporophore,
49.

—, lipoxeny (desertion of
host), 388.

—, structure of sporophore
in endophytic, 57.

Ascomycetous series, 120.

Ascophora elegans, resist-
ance of spores, 347.

Ascospores, 60, 129, 232.

—, capacity of germination,
343-

—, development, 76.

Ascotricha, 211.

Ascus, 60.

— suffultorius, 61.

Ascus-apparatus, 186.

Aseroe, 312, 325.

— rubra, compound sporo-
phores, 326*.

Aserophallus, 312, 325, 326*.

Aspergillus, 252, 256.

— albus, conditions of vege-
tation, 353.

—, capacity of germination,
348.

— clavatus, 253.

— —, conditions of vege-
tation, 353.

— —, mycelial membranes,
21.

— flavescens, parasitism, 370.

— flavus, 256.

— —, capacity of germina-
tion, 344, 348.

— —, parasitism, 369.

— fumigatus, capacity of
germination, 344.

— —, conditions of germi-
nation, 349.

— —, parasitism, 359, 370.

— glaucus, parasitism, 397.

— niger, 206, 257.

— —, conditions of vegeta-
tion, 353.

—-—, effect on the sub-
stratum, 358.

— —, mycelial membranes,
21.

— —, parasitism, 370.

— —, secretion of ferment,
355.

INDEX.

Aspergillus ochraceus, con-
ditions of vegetation, 353.

—, parasitism, 360.

— purpureus, 206.

—, sclerotioid perithecia, 42.

—, simple sporophores, 46.

Assimilation of carbon diox-
ide by Bacteria, 479.

Athelia, 22.

Atichia, 416.

Atractium, 252.

Auricularia, 338.

— Auricula Judae, 306.

— —, basidia, 305 *.

— — ‚formation of spores,62*.

— mesenterica, structure of
sporophore, 58,

— sambucina, 306.

Autoecious, 387.

Autoecism, 387.

Autoxenous, 387.

Azygites, 150.

Azygospores, 150, 159.

Bacidia, 223.

Bacillus,454,458,460,468,473-

— Anthracis, 466 *, 476,477,
478, 482, 486.

— butylicus, 477, 430.

— butyricus, 455, 461, 462,
479.

— erythrosporus, 461.

— Megaterium, 463 *.

— subtilis, 457, 462, 466 *,
467, 476, 477, 479, 486.

— virens, 455-

Bacteria, 454.

—, aerobiotic, 479.

—, affinities, 474.

—, anaerobiotic, 479.

—, arthrosporous, 460, 468.

—, assimilation of carbon
dioxide, 479.

—, capacity of germination,
476.

—, cell-forms, 458.

—, course of development,
459.

—,endosporous, 459,460,475.

—, formation of spores, 460.

—, mode of life, 476.

—, parasitic, 481, 487.

—, resistance of spores, 476,

—, saprophytic, 481, 487.

Bacteridium, 460.

Bacteriopurpurin, 455.

Bacterium, 454, 458, 468,
469, 473.

— butyricum, 477.

— chlorinum, 455.

— cyanogenum, 458.

— merismopoedioides, 469.

— Pastorianum, 456.

— Termo, 478.

505

Bacterium viride, 455.

— Zopfii, 469, 476.

Bactrospora, number of
spores, 79.

Baeomyces, 200.

— roseus, 222.

Balsamia, 195.

Basidia, 45, 61, 286, 302, 305.

—, definitive, 306.

—-, primary (initial), 306.

—, secondary, 306.

—, sterile, 302.

Basidiomycetes,1 20,132,286.

—, angiocarpous, 338.

—, clamp-connections, 2, 19.

—, course of development
and relationships, 328.

—, formation of spores, 61,
63, 67, 68.

—, germ-pores, 100.

— gymnocarpous, 289.

Basidiospores, 339, 340.

—, capacity of germination,
343.

Basidium, 60, 61, 306.

Battarea, 311.

—, capillitium, 8.

— Steveni, 317.

— —, fibres of capillitium,
317 *.

—, thickenings
brane, 8.

Beer-yeast, 267.

Beggiatoa, 455, 459,469, 475-

— alba, 471*, 472*.

— roseo-persicina, 455, 472,
473.

Bion, 123.

Blastema, 401.

Blastenia, 223.

— ferruginea, 223.

Boletus, 288.

—, assumption of a blue
colour in the air, 15.

—, coloration of membranes,
Io,

— edulis, 301.

— elegans, 297.

—, gelatinous membranes, 9,
10.

— luteus, 297.

Botryosporium, formation of
spores, 63.

—, thallus, 1.

Botrytis, 252.

— Bassii, 252.

— —, capacity of germina-
tion, 344.

— —, formation of spores,
65, 65*.

— —, parasitism, 362.

— cinerea, 224, 238, 252,
254.

— —, cell-nucleus, 6.

of mem-

506

Botrytis cinerea, conditions
of germination, 349.

— —, development from a
sclerotium, 38, 41.

— —, gonidiophores, 48.

— —, membrane, 12.

— —, organs of attachment,
21.

— —, resistance of spores,
347.

— —,simple sporophores,48.

— —, thallus, 1.

— erythropus, development
from sclerotia, 41.

Bovista, 11, 309, 310, 315.

—., formation of spores, 64.

— plumbea, -capillitium, 12,
314*, 315.

Brachycladium, 252.

Branching in Bacteria, 458.

— of the thallus, 1.

Bristles on compound sporo-
phores, 59.

Brood-buds, 124, 401, 415.

Brood-cells, 124, 129, 154.

— of Lichens, 417.

Bryopogon divergens,
crustations, 408.

— jubatus, 246.

— —, colouring matter, 408,

—, distribution of Algae in
the thallus, 404.

in-

— ochroleucus, incrusta-
tions, 408.
— sarmentosus, incrusta-

tions, 408.

—, soredia, 415.

—, structure of thallus, 404,
406.

Bulbils, 124, 263.

Bulbus, 292.

Bulgaria, ejection of spores,
89.

—, gelatinous membranes, 9,
13.

— inquinans,
spores, 91.

— —, germination, 115.

— sarcoides, 242.

— —, ejection of spores, 86.

Bursulla crystallina, 446.

Byssaceae (Byssacei), 402.

Byssocaulon niveum, struc-
ture of thallus, 411.

Byssus, 29.

ejection of

Caeoma, 282.

— Euonymi, 282.

— Mercurialis, 282.

— pinitorquum, structure of
spores, 100.

Calathiscus, 312.

Calcareae (Calcariei), 424,

430,435,436, 441, 448,451.

INDEX.

Calcium carbonate in Myce-
tozoa, 435, 436.

— — -vesicles, 430.

— oxalate, 11*, 408.

Callopisma, 223.

Calocera, 288, 305.

—, branching of compound
sporophore, 51.

—, formation of spores, 63.

—, gelatinousmembranes, 12.

—,structure ofsporophore, 58.

Calosphaeria biformis, 239.

—, number of spores, 79.

— princeps, 241.

— verrucosa, number of
spores, 79.

Calothrix in Lichen-thallus,

398.
Calycieae (Calyciei), dis-
charge of spores, 96, 98.
Canker in deciduous trees,

383.
Cantharellus, 288, 297.
— infundibuliformis, deve-
lopment of sporophore, 56.
Cap-fungi, 287.
Capacity of germination, 343.
— in Bacteria, 476.
— in Mycetozoa, 448.
Capillitium, 194, 310, 314.
— in Mycetozoa, 431, 436.
Capitate Bacteria, 461.
Carbon dioxide, assimilation
by Bacteria, 479.
Caries in teeth, 472.
Carpogonia, 212.
Carpospores, 129, 232, 340.
Catopyrenium, structure of
thallus, 406.
Cauloglossum, 319.
— transversarium, 310.
Celidieae (Celidiei), 416.
Cell-forms in Bacteria, 458.
Cell-membrane, 8.
—, gelatinous, 9.
— in Bacteria, 456.
—, lignified, 9.
—, mucilaginous, 9.
—, sclerosed, 9.
—, suberised, 9.
Cell-nucleus, 6.
— in Bacteria, 456.
— in Mycetozoa, 425.
Cellulose in Bacteria, 457.
—inMycet0202,428,441,442.
Cellulose-membrane, 8.
Cellulose-reaction, 13.
Cementation of hyphae, 4.
Cenangium Frangulae, 243.
— fuliginosum, spores, 99.
Cephalodia, 410.
Cephalosporium, 334.
Cephalotheca tabulata, dis-
charge of spores, 97.

Cephalothecium, 252.

Ceratieae (Ceratiei),
427,434, 448.

Ceratium hydnoides, deve-
lopment of sporophores,
432*, 433 *.

— porioides, development of
sporophores, 433, 433 *.

Ceratonema, 29.

Cetraria islandica, chemical
properties, 408.

— —, colouring matter, 408.

— —, Lichen-starch, 10.

— —, structure of thallus,
404, &C.

— straminea, incrustations,

4235

408.

Chaetocladieae (Chaetocla-
diei), 148, 151.

Chaetocladium, 117,147,149,
150, 151, 152, 153, 155.

—, conditions of germina-
tion, 350.

— Fresenii, 150.

— Jonesii, 150.

— —, haustoria, 20.

—, parasitism, 360, 385.

Chaetomieae (Chaetomiei),
260,

Chaetomium, 192, 211, 243,
260.

—, discharge of spores, 97.

— fimeti, 193.

— —, discharge of spores, 97.

—, germination, 111.

—, hairs, 59.

—, resin-excretion, ro.

Chaetostylum, 152.

Chain-gemmae, 155.

Chalara, 267.

— Mycoderma, 267.

Chalara-form, 250.

Change of host, 387.

Cheilaria, 252.

Chiodecton nigrocinctum,
structure of thallus, 411.

Chionyphe Carteri, 379.

Chlamydospores,1 5 4,249,336.

Chlorangium Jussuffii, cal-
cium oxalate, 409.

Chlorophyll, 6.

— in Bacteria, 455, 462, 474.

Chlorosplenium aerugino-
sum, colouring matter, 14.

Choanephora, 150, 153, 154.

Cholera in fowls, 472, 486.

Chondrioderma, 448.

— difforme, 423, 427, 433,
441, 452.

— floriforme, 440.

—,germinationand formation
of plasmodia, 423*, 425*.

Chromidia, 417.

Chroococcaceae, 474.

Chroococcaceae in Lichen-
thallus, 398.

Chroolepus in Lichen-thal-
lus, 397.

— umbrinum, 398 *.

Chrysochytrium, 167.

Chrysomyxa, 277, 282, 338.

— Abietis, 284.

—, abscision of spores, 69.

—, capacity of germination,
344, 349-

—, formation of spores, 66.

— Ledi, 284.

— —, parasitism, 388.

— Rhododendri, 284.

——, abscision of spores,7 1*.

— —, germination, teleuto-
spore-layer, 284 *.

— —, parasitism, 388.

— —, spore-chain, 279*.

— —, structure of spores,
101*,

—, structure of spores, ror*,

Chytridieae (Chytridiei),132,
160, 445, 475. ae

—, capacity of germination,
344.

—., discharge of spores, 82.

—, doubtful species, 170.

—, parasitism, 360, 363, 364,
365, 386, 395.

—, restingstate of spores, 344.

—, swarm-spores, 107.

—, thallus, 5.

Chytridium Brassicae, 162.

— macrosporum, 161.

— Mastigotrichis, 161.

— Olla, 161, 162.

— —, propagation, 165 *.

— roseum, 161.

— vorax, 161.

— —, swarm-spores, 107.

Cicinnobolus, 247, 252, 253.

— Cesatii, pycnidia, 247*.

Cilia, 107, 457.

Circinella, 152.

Cladochytrieae (Cladochy-

triei), 165, 169.

Cladochytrium, 170, 184.

— Iridis, propagation, 166*.

— —, swarm-spores, 108 *.

—, formation of spores, 61.

—, germination, 109.

— Menyanthidis, 166.

Cladonia, 200, 222.

—, cellulose, 13.

— decorticata, 222.

— furcata, Algae of the thal-
lus, 397*, 404. :
— Novae Angliae,spermatia,

2r1*,
— Papillaria, 221, 222.
—, podetia, 402.
— Pyxidata, 222.

INDEX.

Cladiona rangiferina, 222.

— —, structure of thallus,
404.

—, structure of thallus, 404,
406.

Cladosporium, 252.

— dendriticum, parasitism,
393, 394.

—, formation of gonidia, 67.

— herbarum, 229.

—, spores, 68,

Cladothrix, 457, 458, 459,
469, 472.

Clamp-cells, 3.

Clamp-connections, «.

Clathrocystis, 472.

Clathrus, 322.

— cancellatus, 312, 324.

— —, compound sporo-
phores, 324.

— hirudinosus, 312.

—, mycelial strands, 23.

Clavaria, branching of com-
pound sporophore, 51.

—,compound sporophores,48.

— juncea, cellulose-mem-
brane, 8.
— minor, sclerotium, 42.
Clavarieae (Clavariei), 288,
303. P
—, structure of compound
sporophore, 58.

Claviceps, 186, 191, 192, 200,
235,239,244, 246,248, 260.

—, cellulose, 13.

—, fatty matter, 7.

—., formation of gonidia, 65.

—, gonidiophores, 36.

—, inception of sporophore,
49-

—, lipoxeny, 388.

— microcephala
tium), 41.

— nigricans (sclerotium), 41.

—, parasitism, 362.

— purpurea, 220.

— —, development of sporo-
phore, 227*, 228*,

— —, germination of sclero-
tia, 38, 38*.

— —, parasitism, 359.

— —, sclerotia, 36*, 41.

— pusilla, sclerotia, 41.

—, resting state, 37.

—, sclerotia, 30, 31, 33, 35,
36*,.39. :

—, secondary mycelium, 45.

—, spores, 99.

—, structure of ascus, 95.

Cleistocarpous Ascomycetes,
186, 193.

Clitocybe, 297.

Clostridium, 458, 460.

— butyricum, 455, 461.

(sclero-

507

Club-shaped Hymenomy-
cetes, 287.

Coalescence of hyphae, 2.

Cocci, 458.

Coccobacteria septica,”473.

Coccocarpia molybdaea,
Algae of thallus, 409.

Coemansia, 156.

Coenogonium confervoides,
structure of thallus, 411.

— Linkii, structure of thal-
lus, 410*, 411.

Coleosporium, 281, 282, 338.

—, abscision of spores, 69.

— Campanularum, 282.

—, capacity of germination,

— formation of spores, 66.

—Senecionis, parasitism, 388.

Collema, 198, 212, 224, 231,
237) 239, 240, 241.

—cheileum, number of
spores, 79.
— microphyllum, fertilisa-

tion, 212 *.

— —, development of sporo-
phore, 214*.

—, soredia, 415.

—, structure of thallus, 412.

Collemaceae (Collemacei),
211,214, 231,234,258, 402.

—, structure of thallus, 44.

Collenchyma, 316, 328.

Collybia, 297.

Colouring matters, 14.

— of Bacteria, 455, 457.

— of fatty substances, 7.

— of Lichens, 408.

— of Mycetozoa, 424, 434.

Colpodella, 447.

Columella, 152,173, 435,438.

Colus, 312.

— hirudinosus, 325.

— —, receptacle, 326*.

Comatricha, 438.

Commencement of fructifi-
cation (archicarp), 121.

Companion-hyphae, 215.

Completoria, abjection of
spores, 73.

— complens, 160.

— parasitism, 363, 364, 393.

Compound sporophore, 46,
48, 186, 288.

—, development, 49.

— in Ustilagineae, 178, 181,
184.

—, structure, 57.

Concrescence of hyphae, 4.

Conditions of vegetation,
general, 352.

Confervae in Lichen-thallus,
397.

Conidia, 129, 141.

508

Conidiobolus
160.

Conidium, 131.

Conjugation in Ascomycetes,
198.

— in Ustilagineae, 178, 181,
184.

— in Zygomycetes, 145.

Conjugation-cells, 145, 148.

Conoplea, 252.

Conversion of membranes
into mucilage, 9.

— in abscision of spores, 69.

— in Bacteria, 456.

Coprinus, 291, 295, 296, 303,
304, 305, 306, 329, 330,331.

—, abjection of spores, 73.

—, abjunction of spores, 64.

—, cementation of hyphae, 4.

—, clamp-connections, 2.

— comatus, 306.

—, compound sporophores,
49.

—,conditions of germination,
350.

—, duration of growth, 51.

— ephemeroides, 291, 295,
297, 332.

— ephemerus, 297, 303.

—, germination, 111.

—, germ-pore, ror.

—, growth of compound spo-

“ rophore, 50.

— lagopus, 291, 295,296,332.

— —, gonidia, 332 *.

— micaceus, 295, 304, 306.

— —, development of sporo-
phore, 292*.

— —, hymenium, 303*.

—, mode of life, 357.

— niveus, sclerotia, 42.

—, secondary mycelium, 45.

— stercorarius,295, 329, 332.

— —, abjection of spores, 73.

—, capacity of germination,
344 .

— —, germination of sclero-
tia, 38, 39, 42.

— —, sclerotia, 30, 32, 34,
35, 38, 39, 42.

Coprolepeae, structure of
spores, 102.

Cora Pavonia, structure of
thallus, 414.

Corallofungus, 29.

Cordyceps, 186, 191, 229.

— capitata, 221.

— cinerea, parasitism, 359.

—, ejection of spores, 96.

—, formation of gonidia, 66.

—, growth of compound
sporophores, 50,

— militaris, 94, 221, 253,
255, 367.

utriculosus,

INDEX,

Cordyceps militaris, germi-
nation of gonidia, 371*.
— —, parasitism, 359, 362,
367, 371.

— ophioglossoides, 221.

—, parasitism, 362, 367, 371.

—, secretion of ferment, 355.

— sphecocephala, 367.

—, structure of ascus, 95.

Coremium, 48.

Cortex, 193.

Cortical layer of compound
sporophore, 58.

Corticium, 287, 304.

— amorphum, 302.

— —, chemical behaviour of
spore-membranes, 105.

— —, formation of spores,
64*.

— —, maturity of spores,68.

— —, structure of spores,
100, 101.

— calcareum, secretion of
calcium, 11.

— calceum,
spores, 64.

— dubium, 335.

— quercinum, 307.

— —, periodical growth, 57.

Cortina (curtain), 292.

Coryneum, 252.

—, spores, 68.

Course of development in
Fungi, 118.

— in Bacteria, 459.

Craterium, 434.

Crenothrix, 457, 458, 459,
476.

— Kühniana, 469, 470*.

Crepidotus, 333.

Cribraria, 434, 435, 436.

Cribrarieae (Cribrariei), 427,
448.

—, experiments in germina-
tion, 421.

Cronartium, 280.

—, capacity of germination,
345.

—, parasitism, 388.

Crucibulum, 311, 320, 321,
330.

— vulgare, 319.

— —, conditions of germina-
tion, 350.

— —, development of sporo-
phore, 319*, 320*.

— —, membranes, 12.

Crustaceous Lichens, 402.

—, growth in thickness, 407.

Cryptospora, number of
spores, 79.

— suffusa, 239.

Crystalloids, 7.

Ctenomyces, 206.

formation of

Cucurbitaria, 221, 245.

— elongata, 247, 248.

— Laburni, 246, 248, 259.

— —, development ofspores,
78.

— —, ejection of spores, 95.

— —, germination, 114.

— macrospora, 246.

— —, germination, 114.

— —, layer ofgonidia, 246 *.

Cutis, 58.

Cyathus, 311, 320, 321, 329.

—, clamp-connections, 2.

— striatus, 321.

Cyclomyces, 288.

Cylinder-gonidia, 371.

Cylindrosporium, 252.

Cyphella, 287.

Cyphellae, 407.

Cystidia, 303.

Cystococcus in
thallus, 397, 398 *.

— viridis, 397*.

Cystocoleus, 411.

—ebeneus, structure of
thallus, 410 *.

Cystopus, 138, 233.

—, abscision of gonidia, 66*,
69 *.

— Bliti, parasitism, 391.

— candidus, 135, 138.

— —, capacity of germina-
tion, 343.

Lichen-

- — —, conditions of germi-

nation, 349.

— —, fertilisation, 136 *.

— —, germination, 136*,
138*,

— —, gonidia, 138*,

— —, haustoria, z0*.

— —, parasitism, 389, 391.

— cubicus, abscision of
gonidia, 69.

—, development, 134.

—, endogenous formation of
spores, 73.

—, layer of gonidia, 48.

—, parasitism, 363, 386.

— Portulacae, abscision of
gonidia, 66*, 69*.

——, capacity of germina-
tion, 349.

— —, parasitism, 358.

— —, ripeness of spores, 68.

—, structure of spores, 106,
107.

—, swarm-spores, 107.

Cysts, 427.

—, thick-walled, 427.

Cytispora, 252.

Cytisporeae(Cytisporei),251.

Cyttaria, gelatinous mem-
branes, 9, 13.

Cyttarieae (Cyttariei), 186.

Dacryomitra, 288, 305.

Dacryomyces, 288, 305, 306,
329, 331.

— deliquescens, 331.

—, formation of spores, 63,
64.

—, gelatinousmembranes, 13.

Dactylium, 249.

—, formation of spores, 65*.

— macrosporum, coloration
of membrane, 8.

—, pits, 13.

Dactylococcus in Lichen-
thallus, 397.

Daedalea, 288.

—, hyphal weft, 3.

—, membranes, 12.

—, mycelial membranes, 22.

— quercina, cellulose, 8, 13.

—, suberisation of mem-
branes, 9.

Delastria, 195.

Dematieae (Dematiei), mem-
brane, 12.

—, spores, 68.

Dematium, 29.

—, germination, 114.

— herbarum, formation of
gonidia, 67.

— pullulans, sprouting, 27 1*-

Dendryphium, 252.

Dermatea amoena, 243.

— carpinea, 243.

— Coryli, 243.

— dissepta, 243.

Dermatocarpon, 192.

Desertion of host (lipoxeny),
388.

Diachea, 434, 436.

— elegans, 424.

Diatrype, 186, 192, 218, 240.

—, number of spores, 79.

— quercina, spermogonia,
241*.

— —, number of spores, 79.

— verrucaeformis, number
of spores, 79.

Dictydium, 427, 431, 435.

Dictyonema, structure ©
thallus, 414.

Dictyostelium, 442, 451.

Dictyuchus, 143.

— clavatus, 144.

— — formation ofspores,75.

—, formation of spores, 74.

— monosporus, formation of
spores, 75.

—, swarm-spores, 108.

Diderma, 434, 436.

Didymium, 430, 436, 441,
448.

— difforme, 427, 428, 429.

— farinaceum, 436.

— leucopus, 423,424,428,436.

INDEX.

Didymium leucopus, plasmo-
dium, 425*.

— —, sporangium, 434*.

— Libertianum, 423, 441.

— nigripes, 436.

— physaroides, 436.

— Ppraecox, 423, 424, 427.
— Serpula, 424, 425, 428,
429, 430, 434, 436, 452.
— squamulosum, sporan-

gium, 434*.
Dimargariscrystalligena,156.
Diplodia, 247.

—, germination, 111.

—, secretion of resin, 10.

Discocarp, 187.

Discomycetes, 186, 187, 189.

—, as Lichen-fungi, 396.

—, ejection of spores, 85, 86,
89.

—, glycogen, 6.

—, puffing of spores, go.

Discus, 187.

Diseases in silk-worms, 486,

489.

Dispira cornuta, 156.

Dissepiment, 301.

Doassansia, 173.

Dothidea, 191.

— Melanops, 246.

— Ribesia, germination, 114.

— Sambuci, number of
spores, 79.

— Zollingeri, 245.

Effect of parasite on host,
367.

Ejection of spores, 84.

Elaphomyces, 193.

—, asci, 77.

—, conditions of germina-
tion, 352.

—, discharge of spores, 81,97.

— granulatus, 193.

— —,development of spores,
80.

—, mycelial strands, 22, 23.

—, number of spores, 79.

Empusa, 158.

—, abjection of spores, 73.

— Grylli, 159.

— macrospora, 158.

— Muscae, 158, 159.

Encarpium, 17.

Enchylium, structure of
thallus, 413.

Endocarpon, 192.

— miniatum, 222.

— monstrosum, calcium ox-
alate, 409.

— pusillum, 224, 409.

— —, Algae of thallus, 409.

— —, formation of thallus,
400.

509

Endocarpon pusillum, germ-
ination, 339*.

— —, hymenial Algae, 400,
401.

— —, number of spores,
79.

— —, structure of thallus,
406.

Endomyces, 341.

— decipiens, 266.

Endophyllum, 278, 281, 285.

— Euphorbiae, 281.

— —, parasitism, 364, 368,
390.

— Sempervivi, 277, 281.

— —, germination, 279*.

— —, parasitism, 390.

Endophytes, 360.

—, behaviour to the living
cell, 393.

Endopyrenium, structure of
thallus, 404.

Endosporium, 100.

Enerthenema, 438.

Entomophthora, 158.

—, abjection of spores, 73.

— curvispora, 158, 159.

—, formation of spores, 62.

— ovispora, 158, 159.

—, ‘pleomorphism,’ 126.

— radicans, 158, 159.

Entomophthoreae (Entomo-
phthorei), 132, 158, 184.

—, parasitism, 362, 367, 371.

Entyloma, 172, 173, 174, 178,
179, 180, 181.

— Calendulae, germination,
175*.

— —, parasitism, 389.

—, formation of spores, 61.

— Magnusii, 179.

—, parasitism, 362.

— Ranunculi, 179, 180.

— serotinum, 180.

— Ungerianum,
tion, 175*.

Envelope-apparatus in As-
comycetes, 186.

Envelope of plasmodia of
Mycetozoa, 426.

Ephebe pubescens, 242.

— —, structure of thallus,
412*,

— structure of thallus, 412.

Epichloe, 186, 191, 192, 200,
221, 244, 246, 260,

—, abscision of gonidia, 71.

—, structure of sporophore,
57.

— typhina, formation of
gonidia, 65.

— —, Parasitism, 359, 386,
- 390, 391.

— —, structure of ascus, 95.

germina-

510

Epinasty of pileus in Agari-
cineae, 50, 289.

Epiphragm, 320.

Epiphytes, 360.

Epiplasm, 77.

Episporium, 100.

Eremascus, 187, 232, 233,
234, 236, 237.

— albus, 197, 224.

—, development of ascus,
198*,

Ergot, 35.

Erysipelas, 486.

Erysiphe, 202, 232, 236, 238,
239, 245, 352.

— Aceris, parasitism, 394.

—, asci, 76.

— communis, conditions of
germination, 352.

—, discharge of spores, 86.

— Galeopsidis, 203.

— —, conditions of germina-
tion, 352.

— graminis, 203.

— —, conditions of germina-
tion, 352.

— —, haustoria, 19.

— guttata, number of spores,
79.

— —, parasitism, 359, 394.

—, hairs, 59.

—, number of spores, 79.

—, parasitism, 359, 363.

— spiralis, 225.

— Tuckeri, haustoria, 19*.

Erysipheae (Erysiphei), 193,
198, 199, 201, 225,235,244.

—, conditions of germination,
350.

—, discharge of spores, 85.

--, formation of gonidia, 66.

—, haustoria, 19*.

—, mycelium, 19*.

—, parasitism, 386, 393.

Euchytridieae (Euchytridei),
164.

Eurotium, 193,198, 204, 226,
232, 234, 236, 237, 239,
245.

—, abscision of gonidia, 70.

—, asci, 76.

— Aspergillus glaucus, con-
ditions of vegetation, 353.

— —, formation of gonidia,
70*,

— —, parasitism, 369.

—, capacity of germination,
348.

—, compound sporophores,

49.
—, discharge of spores, 81,
97,98. |
—, formation of spores, 62.
—, parasitism, 369.

INDEX.

Eurotium repens, conditions
of vegetation, 353.

— —, development of sporo-
phore, 203*.

— —, parasitism, 369.

—, resinous excretion, Io.

—, simple sporophores, 46,

—., structure of spores, 100,

—, taking up of colouring
matter, 14.

Eusynchytrium, 167.

Eutypa, 191, 218.

—, discharge of spores, 97.

Evernia flavicans, 406.

— furfuracea, colouring mat-
ter, 408.

— —, structure of thallus,
406.

—, soredia, 415.

—, structure of thallus, 404.

— vulpina,incrustations,408.

— —, structure of thallus,
408.

Excipulum, 188,

Exidia, 287, 305.

—, gelatinous membranes, 13.

— recisa, 337.

— spiculosa, basidia, 305*.

— —, formation of spores,
62*,

Exoascus, 265, 266.

— alnitorquus, 265, 266.

— aureus, 265.

— bullatus, 266.

— deformans, 265.

—, ejection of spores, 89.

— epiphyllus, 266.

—, germination, 114, 115.

—, number of spores, 79.

—-, parasitism, 368, 386, 390,

393-

— Populi, 266.

— Pruni, 265, 266.

— — ‚development of spores,
79.

——,, ejectionofspores, 86,92.

— —, inception of sporo-
phore, 49.

— —, parasitism, 393.

—, structure of spores, 100,

— Ulmi, 266.

Exoascus-group, 269.

Exobasidium, 271, 287, 329,
331, 368.

— Lauri, parasitism, 368.

—, parasitism, 386.

— Vaccinii, parasitism, 362,
368.

Exosporium, 100, 135, 252.

—, spores, 68.

— Tiliae, germination, 114.

Fatty matters, 7.
Favolus, 288.

Favus, 376.

Feeder (host), 358.

Felted tissue, 5.

Ferment, secretion, 355,452.

Fermentation caused by Bac-
teria, 481.

— — by Fungi, 384.

Ferns, course of develop-
ment, 120,

Fertilisation-tube, 134.

Fibrillaria, 29.

Filamentous Fungi, 1.

Filamentous sporophore, 46.

Fistulina, 302.

— hepatica, 300, 302, 334.

Flacherie (in silk-worms),
486, 489.

Flagella, 107, 422, 457.

Flagellatae, 445, 475.

Flower of tan, 431.

Flowering plants, course of
development, 121.

Flowers of wine, 267, 358.

Foliaceous Lichens, 401.

Food, a condition of ger-
mination, 351.

Food-material of Fungi, 353.

Form-genera, 119, 459, 473.

Form-species, 119, 459, 473.

Fowl-cholera, 472, 456.

Frill (in Hymenomycetes),
See Armilla.

Frog-spawn
469.

Fructification, 120,

Fruticose Lichens, 401.

Fuligo, 423, 424, 425, 428,
429, 431, 440, 448, 449,
450, 452.

— varlans, 424, 439, 441.

Fumago, 245, 247, 249, 251,
253, 254, 271.

—, formation of gonidia, 66,

— salicina, 244.

Fungi, affinities, 337, 340.

—, course of development,
118.

—, genealogy, 337, 340.

Fungus-body, 2.

—, compound, 2.

—, sclerotioid, 190.

—, slimy mucilaginous, 9.

Fungus-cellulose, 8, 13.

Funiculus, 321.

Fusarium heterosporum, re-
sistance of spores, 346.

Fusiform rods in Bacteria,
458.

Fusisporium, 249, 252.

— Solani, 245.

—, spores, 68.

(Bacterium),

Galls, 369.
Gametes, 120, 148, 150,

Gastromycetes, 286, 308, 337.

Gastromycetes, compound
sporophores, 49.

— conditions of germination,
352.

—, development of sporo-
phore, 50.

—, formation of spores, 63*.

—, gelatinous membranes, 9.

—, membranes, 11, 12.

—, structure of sporophore,
58.

Gattine, 488.

Gautieria, 308, 337.

Geaster, 308, 309, 311, 315,
316, 317.

—, capillitium, 12.

— coliformis, 314.

— —, capillitium - threads,
314*.

— fimbriatus, 314, 316, 317.

— fornicatus, 314, 316, 317.

— hygrometricus, 308, 309,
313, 315, 316, 317.

— —, compound
phores, 316*.

— —, formation of spores,
63%.

— —, gelatinous membranes,
9, 12.

— mammosus, 314, 317.

— rufescens, 317.

— tunicatus, 309.

Gelatinisationof membranes,

sporo-

9.

— in abscision of spores, 69.

— in Bacteria, 456.

Geminella Delastrina, 174.

Gemmae, 60, 61, 154, 155,
230, 328, 330, 331.

Gemmae-cups (in Lichens),
407.

Genabea, 195, 196.

Genea, 196.

—, mycelial strands, 22.

—., structure of spores, roo.

Genealogy of Fungi, 337,340.

Geoglossum, 189.

—, development of spores,
78.

—, ejection of spores, 86.

—, hirsutum, development of
spores, 78.

Germ-pore in Mycetozoa,
441.

Germ-pores, 100, III.

Germ-tube, 1, 110.

Germination, 109, 130.

— in Bacteria, 462, 465, 467.

— in Mycetozoa, 448.

—, conditions of, 349.

— — in Bacteria, 462, 477.

— — in Mycetozoa, 448.

— phenomena of, 343.

INDEX.

Germination of spores, 109.
Gleba, 193, 309.

Gloeocapsa in Lichen-thal-
lus, 397*, 398.
Gloeosporium, 252.

Glycogen, 6, 77.

Gnesiolichenes, 402.

Gomphidius, 297.

Gonatobotrys, 252.

—, formation of
63.

—, gonidia, 98.

—, simple sporophores, 47.

Gonidia, 45, 60, 129, 131,
179, 180, 239, 244, 331,
334, 338, 340.

—, accessory, 146.

—, capacity of germination,
343.

— in Lichens, 417.

Gonidial layer
layer), 417.

Gonidiophore, 45, 245.

Gonionema, structure of
thallus, 412.

Gonoplasm, 134.

Granulose in Bacteria, 455,
461.

Graphideae (Graphidei),
origin of thallus, 399.

—, soredia, 415.

—, structure of thallus, 410.

— subcortical thallus, 402.

Graphiola, 173.

Graphis scripta, origin of
thallus, 399.

— —, Algae of thallus, 398*.

— —, structure of thallus,
410.

Graphium, 29.

Green rot in wood, 14.

Growth of parasites, 367.

— of Fungus-bodies, 3, 50.

Guepinia, 287, 305.

— contorta, structure of
sporophore, 58.

—, gelatinous membranes, 13.

— helvelloides, 287.

Guttulina, 443.

— protea, 442, 443.

Guttulinae, 442.

Gymnoascus, 198, 199, 206,
224, 232, 235.

Gymnomycetes, 251, 252.

Gymnosporangium, 279.

—, parasitism, 388.

— Sabinae, 276.

Gyrocephalus, 287.

Gyrophora, 189.

— cylindrica, spermogonium,
240.

spores,

(gonimic

Haematomma ventosum,
structure of thallus, 405.

511

Hairs of compound sporo-
phores, 59.

Haplocystis mirabilis, 170.

Haplomycetes, 252.

—, thallus, 1.

Haplotrichum, 252.

—, formation of spores, 62,63.

—, simple sporophores, 47.

Haustoria, 18, 19*.

Hay-bacillus, 467.

Helicosporangium, 263.

Helicostylum, 152.

Heliotropism in plasmodia,
449.

Helminthosporium, 252.

—, spores, 68.

Helotium, ejection of spores,
86.

Helvella, 189.

— crispa, ejection of spores,
86.

— —, puffing of spores, 92.

— —, structure of sporo-
phore, 58.

— elastica, development of
spores, 77.

— —, structure of sporo-
phore, 58.

——, structure ofspores,106.

— esculenta, development of
spores, 77.

— —, germination, 113*.

— —, structure of sporo-
phore, 58.

— —, structure of spores,
106.

—, structure of sporophore,
57.

Hemiarcyria, 437, 440.

— clavata, 437.

— rubiformis, 437, 438, 440.

Hemileia, 274.

—, capacity of germination,
345.

— vastatrix, 282.

— —, parasitism, 388.

Hemipuccinia, 279.

Hendersonia, 252.

Himantia, 29.

Homologies of stages of de-
velopment, 119.

— restored, 123.

— interrupted, 123.

Host (vegetable and animal),
358..

—, reaction on parasite, 366,

Hyacinth, yellow sickness,
482.

Hydneae, 288, 303, 333.

Hydnobolites, 195.

Hydnocystis, 196.

Hydnotria, 196.

Hydnum auriscalpium, hairs,
59.

512

Hydnum cirrhatum, 301.
— diversidens, 307.

— —, parasitism, 384.

— Erinaceus, 335.

— —, gelatinous membranes,

9.

— gelatinosum, 301.

— zonatum, 301.

Hydrotropism in plasmodia,
449, 450.

Hymenial Algae, 400, 401.

Hymenial gonidia, 417.

Hymenium, 49, 191, 300.

Hymenochaete, 303.

Hymenogaster, 308.

— —, clamp-connections, z.

— —, formation of spores,
63.

— Klotzschii, 309, 313.

— —, formation ofspores,63.

— —, germ-pores, 101.

Hymenogastreae (Hymeno-
gastrei), 308, 309, 310,
313, 337.

—, conditions of germina-
tion, 352.

—, formation of spores, 63.

—, mycelial strands, 22, 23.

Hymenomycetes, 286, 287,
337.

—, abjection of spores, 73.

— as forming Lichens, 396,
414.

—, capacity of germination,
343.

—, compound sporophores,
48.

—, ferment-secretions, 355.

—, formation of spores, 63.

—, gelatinous membranes, 9,
12.

—, glycogen, 6.

—, growth of compound
sporophores, 51, 55.

— —, periodic, 51.

—, gymnocarpous, 289, 296.

—, membranes, 12.

—, mycelial membranes, 21,
22.

—, parasitism, 384.

—, sclerotia, 32.

—, structure of spores, 106.

—, veiled, 289, 296.

Hymenophorum, 300,

Hypertrophy, 368.

Hypha (proper name), 29.

Hypha, 1.

—, Woronin’s, 199, 218.

Hyphae, ascogenous, 186,
208, 214.

—, cementation, 4.

—, coalescence, 2.

—, concrescence, 4.

Hyphal weft, 3.

INDEX.

Hyphasma, 29.

Hypholoma, 197.

Hyphomycetes, 251.

—, abscision of spores, 71.

—, absence of calcium, 11.

—, thallus, 1.

Hypochnus, 287.

— centrifugus, basidia, 301*.

— —, gonidial layer, 48.

— —, sclerotia, 32, 40, 42.

—, clamp-connections, 2.

—, mycelial membranes, 22.

— purpureus, 306.

Hypocopra, 198, 210,

— finicola, 210, 224, 261.

—, structure of spores, 102.

Hypocrea citrina, number of
spores, 79.

—, formation of gonidia, 65.

— gelatinosa, number of
spores, 79.

— lenta, number of spores,
79.

— rufa, 253.

—, number of spores, 79.

Hypodermii, 184.

Hypomyces, 245, 249, 254.

— armeniacus, sclerotia, 41.

— asterophorus, 336.

— Baryanus, 336.

—, capacity of germination,
345.

— chrysospermus, 249.

—, detachment of spores, 68.

—, formation of gonidia, 65.

— rosellus, 249.

— Solani, 246, 249.

Hyponasty of pilei of Agari-
cineae, 56, 289.

Hypothallus, 405.

Hypothecium, 188.

Hypoxylon,186,218,244,248,

— concentricum, discharge
of spores, 104.

Hysterangium, 308, 310.

—clathroides, gelatinous
membranes, 12.

— gelatinous membranes, 9.

Hysterineae (Hysterinei),
190.

—, parasitism, 386.

—, structure of spores,roz.

Hysterium macrosporum,
gelatinous membranes, 9.

— nervisequum, structure of
spores, 102.

Tleodictyon, 312.

Imbricaria caperata, incrus-
tations, 408.

— incurva,
408.

— saxatilis, 246.

— sinuosa, 246.

incrustations,

Imbricaria soredia, 415.
— tiliacea, Algae of thallus,

398%,
Incipient mycelium, 178.
Incrustations of Lichens,
408,

Inner membrane of spores,
100.

Interstitial substance in spo-
rangium of Mucorini, 75.

Intralamellar tissue, 301.

Invertin, 355.

Involucrum, 289.

Involution-forms, 458.

Irpex, 288.

Isaria, 48, 273.

— brachiata, branching, 51.

—, capacity of germination,
344.

— farinosa, 255.

— —, parasitism, 362.

— strigosa, 253.

Isidium, 406.

Kickxella, 156.
Kneiffia, 287.

Laboulbenia Baeri, parasi-
tism, 359.

— flagellata, 263*.

— Nebriae, 264.

— vulgaris, 264.

Laboulbenieae
niei), 263.

—, parasitism, 360, 365, 367,
370.

—, thallus, 5.

Lactarius, 298,
304.

— chrysorrhoeus, 298, 301.

— deliciosus, 298, 303, 304.

— mitissimus, 298, 302.

— pallidus, 298.

—, pseudo-parenchyma, 3.

— subduleis, 301.

— —, structure of sporo-
phore, 299*.

Lagenidium, 139.

Lamellae, 288.

Lamia culicis, 159.

Lamina proligera, 187.

Lamina sporigera, 187.

Lateral branches in Sapro-
legnieae, 141.

Laticiferous tubes, 299.

Laudatea, structure of
thallus, 414.

Layer (stroma, receptacu-
lum), 48.

Lecanactis illecebrosa, Al-
gae of thallus, 398*.

—-—, structure of thallus,
qıı.

Lecanora, 223.

(Laboulbe-

299, 301,

Lecanora pallida, develop-
ment of spores, 78.
— —, thallus, 400, 402, 405.

— subfusca, apothecium,
190*,
— Villarsii, structure of

thallus, 405.

Lecidea, 223.

— confervoides, structure of
thallus, 405.

— enteroleuca, structure of
thallus, 405.

— formosa, 222.

— geographica, structure of
thallus, 405.

— parasema,
thallus, 405.

— sabuletorum, 245.

Lecidella enteroleuca, de-
velopment of spores, 78.

——,growth of thallus,
404*.

Lempholemma, structure of
thallus, 412.

Lenzites, 288, 301.

— betulina, membranes, 12.

—, growth of compound
sporophores, 57.

Leocarpus vernicosus, 424,
434.

Leotia, 189.

— lubrica, development of
spores, 78.

Lepiota procera, 297.

Leptochrysomyxa, 283.

— Abietis, 338.

—, capacity of germination,
345.

Leptogium, 198.

—, structure of thallus, 412,

structure of

413.
Leptomitus brachynema,1 44.
— lacteus, 144.

—, formation of spores, 74.

Leptopuccinia, 283, 344.

— annularis, 283.

—, capacity of germination,
344, 348.

— Circaeae, 283.

— Dianthi, 284.

— —, parasitism, 361, 362.

— Malvacearum, 284.

— Veronicae, 283.

Leptopuccinieae (Leptopuc-
ciniei), 283, 338.

Leptosphaeria Doliolum,
247.

Leptothrix, 458, 459.

— buccalis, 456, 472.

Leptothyrium, 252.

Lesions in spores, effect on
capacity of germination,
346.

Leucochytrium, 167.

[4]

INDEX.

Leuconostoc mesenterioides,
457, 469.

Libertella, 252.

Licea, 435, 436.

— flexuosa, 434, 435, 441.

— pannorum, 423, 441.

— Serpula, 441.

Lichen-acids, 10, 408.

Lichen-fungi, 188, 224, 242.

—, conditions of germina-
tion, 350.

—, ejection of spores, 93.

—, gelatinous membranes, 9.

—, mode of life, 395.

—, parasitism, 360, 366, 367,
386.

—, resistance of spores, 346.

—, swelling of membrane, 9.

Lichen-sporocarps, 222.

Lichen-starch, 10, 408.

Lichen-thallus, 59.

—, chemical constitution, 407.

—, crustaceous, 401.

—, epiphloeodic, 402.

—, foliaceous, 401.

—, fruticose, 401.

—, growth, 4or.

—, heteromerous, 402.

—, homoiomerous, 402.

—, hypophloeodic, 402.

—, mode of origination, 398.

—, subcortical, 402.

—, structure, 401.

Lichens, 396.

—, cell-membranes, 8.

—, colouring matter, 408.

—, ejection of spores, 87.

—, historical remarks, 416.

—, hyphal weft, 3.

—, number of spores, 79.

—, pseudo-parenchyma, 3.

—, swelling of membrane, 9.

—, thallus, 1.

—, true, 402.

Lichenaceae
402,

Lichenin, 10, 407.

Lichenosphaeria, structure
of thallus, 412.

Lichina, discharge of spores,
96.

—, structure of thallus, 410.

Lichinic acid, 408.

Lignification of membranes, 9.

Lindbladia, 431.

Lipoxeny (desertion of host),

(Lichenacei),

3838,

Long rods (Bacilli), 458.

Loss of capacity in sporo-
phores of Ascomycetes,
254.

Lycogala, 423, 427, 431, 440,
452.

— epidendron, 440, 441.

Ll

513

Lycoperdaceae (Lycoper-
dacei), 308, 310, 311, 313,
337.

—, experiments in germina-
tion, 352.

—, mycelial strands, 22, 23.

—, pseudo-parenchyma, 3.

Lycoperdon, 11, 308, 309,
310, 314, 315.

—, abjunction of spores, 64.

— Bovista, 314.

— giganteum, 314.

— perlatum, 316,

—, pits, 13.

— pyriforme, formation of
spores, 63*.

Lyngbya in Lichen-thallus,
398.

Lysurus, 325.

Macrococci, 458.

Macrogonidia, 225.

Macrosporium, 252.

— Sarcinula, 229.

Madura-disease, 379.

Main series of Fungi, 120.

Malignant oedema, 486.

Mallotium Hildebrandtii,
structure of thallus, 413*.

—, structure of thallus, 412,

413.

Marginal veil (in Hymeno-
mycetes), 290.

Martensella, 156.

Massaria, 192.

— Platani, 258.

—, structure of spores, 102.

Mechanism for abjection of
cells, 72, 85.

Medulla (Medullary layer)
of Lichen-thallus, 403,

—of compound sporo-
phores, 58.

Megalogonidia, 225.

Megalospora affinis, calcium
oxalate, 409.

— —, germination, 112*.

—, number of spores, 79.

— sanguinea, calcium oxa-
late, 409.

Melampsora, 281.

— Göppertiana, parasitism,
388, 390, 391.

— populina, 280, 282.

— salicina, 282.

Melanconis,
114.

—, structure of spores, 102,

Melanconium, 252.

—, spores, 68.

Melanogaster, 309, 310.

—, gelatinous membranes, 9,
13.

Melanospora, 191, 192.

germination,

514

Melanospora parasitica, 191,
198, 199, 210, 211, 226,
235, 251, 365.

— —, discharge of spores, 97.

— —, parasitism, 360, 365,
366.

— —, structure of spores,
106.

Melanotaenium, 176.

Melogramma Bulliardii, ger-
mination, 114.

Membranes of vegetative
cells, 11.

Mentagra parasitica, 376.

Merispores, 98.

Merulius, 288.

Mesentericae, 424.

Metamorphosis, 256, 259.

—, mycetogenetic, 368.

Metoecious, 387.

Metoecism, 388.

Metoxenous, 387.

Micrococcus, 459, 473.

— Bombycis, 489.

— prodigiosus, 455.

— —, taking up of colouring
matter, 14.

Microcysts, 427.

Microgonidia, 225.

Microgonidium, 419.

Micropuccinia, 285.

Microsomata, 455.

Microsporon Audouini, pa-
rasitism, 376.

— furfur, parasitism, 376.

— Mentagrophytes, parasi-
tism, 376.

Milk, blue, 462.

Mitremyces, 312, 326.

—, gelatinous membranes, 9,

13.
Mode of life of Bacteria, 476.
— of Mycetozoa, 448.

— of Fungi, 343.
Monad-forms, 458.
Monadopsis, 447.

Monas Amyli, 447.

Monoblepharis, 132, 140,
141.

— sphaerica, fertilisation,
140*,

—, swarme-spores, 107, 109.

Montagnites, 297.

Morchella, 189.

—, ejection of spores, 89.

— esculenta, development of
spores, 77.

— —, ejection of spores, 85.

—, structure of sporophore,
37.

Moriola, 416.

Morioleae (Moriolei), 416.

Mortierella, 146, 149, 150,
151, 154, 155.

INDEX,

Mortierella,
spores, 83.

—, haustoria, 20.

— nigrescens, 150.

— reticulata, resistance of
spores, 346.

— Rostafinskii, 150.

— —, experiments in germi-
nation, 352.

Mosses, course of develop-
ment, 120.

Mother of vinegar, 456, 458,
481.

— -fungus, 472.

Moulds, fatty matters, 7.

Mucor, 149, 152, 155.

—circinelloides, ferment-
production, 358.

— corymbifer, parasitism,
360.

—, discharge of spores, 83.

—, ferment-production, 358.

— ‚formation of spores,7 4,75.

— fusiger, 150, 152.

— —, cellulose-membrane,8.

— —, resistance of spores,
346.

—, mode of life, 357.

— Mucedo, 150, 154.

— —, cellulose-membrane,8.

— —, ferment - production,
358. De

— —, germination, 113.

—, parasitism, 380.

— plasmaticus, formation of
spores, 75.

—, pleomorphism as alleged,
126.

— racemosus, 150.

— —, conditions of vegeta-
tion, 354.

— —, ferment - production,
358. ali

— —, parasitism, 380.

—, resistance of spores, 347.

— rhizopodiformis, parasi-
tism, 359, 360, 370.

—, simple sporophores, 46.

— spinosus, ferment - pro-
duction, 358.

— stolonifer, 147, 150, 152.

— —, conditions of germi-
nation, 350, 352.

— —, conjugation, 148*.

— —, ferment - production,
358. a

— —, germination, 113.

-— —, parasitism, 380.

— —, resistance of spores,
347.

— —, secondary mycelium,
46.

—, taking up of colouring
matter, 14.

discharge of

Mucor tenuis, 150.
Mucor-yeast, 156.
Mucoreae(Mucorei),148,151.
Mucorin, 7.

Mucorineae (Mucorini), 132,
145, 169, 232, 233, 236,
271.

—, calcium oxalate, ır.

—, capacity of germination,
348.

—, cell-nucleus, 6.

—, conditions of germina-
tion, 350.

—, crystalloids, 7.

—, doubtful, 156.

—, ferment-secretion, 358.

—, formation of spores, 75.

—, gemmae, 60, 61.

—, germination, 113.

—, glycogen, 6.

—, parasitism, 363, 385.

—, resting-state of spores,
344:

—, simple sporophores, 46.

—, thallus, 1.

Muscardine, 374.

Mushrooms,cell-membranes,
8.

—, thallus, 1.

Mutualism, 369.

Mycelial membranes, 18, 21.

Mycelial strands, 18, 22.

Mycelium, 18.

—, filamentous, 18.

—, fibrillose, fibrous, 18.

—, sclerotioid, 42.

—, secondary, 45.

Mycena, 297.

—, cementation of hyphae, 4.

—, gelatinous membranes,
9, 13.

Mycenastrum, 315.

— corium, 315.

— —, capillitium - threads,
314*.

Mycetozoa, 411.

—, affinities, 442.

—, doubtful, 446.

Mycoderma, 22,

— aceti, 481.

Mycoderma-form, 250.

Mycogone, 245, 252.

Mycoidea parasitica in
Lichen-thallus, 398.

Mycoprotein, 457.

Mycosis, 369, 370,

Mycothrix, 458.

Myelin, 300.

Mylitta, 42.

Myriangium, 193, 416.

— Durieui, 197.

Myriocephalum botryospo-
rum, structure of spores,
103.

Mystrosporium, 229, 252.

Myxamoebae, 423.

Myxastrum radians, 447.

Myxocyclus, 252.

— confluens, structure of
spores, 102,

Myxogasteres, 421.

Myxomycetes, 421, 475.

—, affinities, 442.

Myzocytium globosum, 139.

Naemaspora, 252.

Naetrocymbe, 416.

Neck in perithecia, 191.

Nectria, 200, 215, 221, 239,
245.

— cinnabarina, 244, 246.

— —, parasitism, 362, 383.

— cucurbitula, parasitism,
383..

— development of spores,
78. A

—, discharge of spores, 97.

— ditissima, 228.

— —, parasitism, 383.

—, germination, 114, 115.

— inaurata, 114, 115.

— Lamyi, germination, 115.

— Solani, 246,

— —, abscision of gonidia,
71.

Nephroma arcticum,Algae of
thallus, 409.

—, structure of thallus, 406.

Nephromium, Algae of
thallus, 409.

New formation of members
caused by Fungi, 368.

Nidularia, 311, 320.

Nidularieae (Nidulariei), 308,

312, 319, 332.
—, gelatinous membranes,

13.

—, mycelial strands, 22, 23.

Nosema Bombycis, 488.

Nostoc in Lichen-thallus,
397%, 398.

Nostocaceae, 475.

— in Lichen-thallus, 398.

Nucleariae, 447.

Nuclei in spores, 106.

Nuclein, 6.

Nucleus in perithecia, 193.

Nummularia, 218.

—, discharge of spores, 97.

Nutritive adaptation, 356.

Nyctalis, 297, 334, 341.

— asterophora, 335, 341.

——, compound sporo-
phores, 335*.

— mycrophylla, 336.

— parasitica, 336.

— —, development of sporo-
phore, 55.

INDEX.

Obelidium, 164.

Obryzum, structure of
thallus, 412.

Ochrolechia pallescens, cal-
cium oxalate, 409.

— —, germination, 112.

— —, structure of thallus,
405.

— tartarea, calcium oxalate,
408.

Octaviania, 308.

— asterosperma, compound
sporophores, 308*,

-— —, hymenium, 309*.

— carnea, 309, 313.

— —, formation of spores,
63%.

—, structure of spores, 100.

Oedema, malignant, 486.

Oidium, 238, 252.

— albicans, parasitism, 377.

— aurantiacum, resistance
of spores, 347.

— erysiphoides, 252.

— fructigenum, 252.

— lactis, 252, 253, 377.

— —, cell-nucleus, 6.

=e formation of sporesy

7.

— leucoconium, 252.

— Tuckeri, 225.

— —, parasitism, 387.

Oil-drops in spores, 106.

Olpidieae (Olpidiei), 166, 167,
168, 169, 170.

Olpidiopsis, 444.

— fusiformis, 166.

—, parasitism, 393.

— Saprolegniae, 161, 166.

Omphalaria, structure of
thallus, 413.

Omphalarieae (Omphalariei),
structure of thallus, 413.

Omphalia, 297.

Onygena, 193.

— corvina, 196.

— —, conditions of germina-
tion, 351.

—, discharge of spores, 97.

— equina, 197.

— faginea, 335.

Oogonia, 120, 133.

Oosphere, 120, 133.

Oospores, 129, 232.

—, capacity of germination,
343.

—, resting state, 344, 345.

Opegrapha filicina, 397.

— —, structure of thallus,

4il.
— plocina, structure of
thallus, 411.
— saxatilis, structure of

thallus, 411.
tle

515

Opegrapha varia, 246.

— —, structure of thallus,
4il.

— vulgata, 246.

Ophidomonas, 472.

Organs, functionless in As-
comycetes, 256.

— of attachment, 45.

— of propagation, 124.

Ostiole of perithecium, ıgr.

Otomycosis aspergillina, 369.

Outer envelope of ascocarp,
188,

Oxygen as a condition of
germination, 349.

Ozonium, 29.

Palmellaceae in Lichen-
thallus, 397.

Palmellae-forms in Bacteria,

459.

Panhistophyton, 488.

Pannaria, 223.

—, structure of thallus, 410.

Panus stypticus, structure of
sporophore, 58.

— —, gelatinous membrane,
13.

Papulospora, 2.

Paraphyses, 48, 76, 187, 192,
286, 302.

— envelope, 275.

Parasites, 356, 358, 48r.

—, autoecious, 387.

—, autoxenous, 387.

—, facultative, 356, 369.

—, inhabiting animals, 369.

—, inhabiting plants, 379.

—, metaxenous, 387.

—, metoecious, 387.

—, obligate, 356.

— which change their host,
387. :

Parmelia, Algae of thallus,

409.
— pulverulenta, 222.

—, soredia, 415.

— stellaris, 222.

—, structure of thallus, 406.
Paulia, discharge of spo es,

97.
—, structure of thallus, 413.
Paxillus, 297.
Pébrine, 488.
Peccania, structure of
thallus, 413.
Pellicula (cutis), 58.
Peltigera, 240.
—, Algae of thallus, 409.

— aphthosa, structure of
thallus, 406.
— canina, structure of

thallus, 406.
—, incrustations, 408.

516

Peltigera malacea, structure
ofthallus, 406.

—, structure of thallus, 404,
406.

Penicillium, 193, 198, 199,
226, 232, 234, 239, 245,
251, 254.

—, abscision of gonidia, 66,
70*,

— aureum, 206.

—, capacity of germination,
348.

—, conditions of germination,
350.

—, conditions of vegetation,
353, 354-

—, discharge of spores, 81,
97.

—, effect on substratum,
358.

—, fatty matters, 7.

—, formation of spores, 62.

—, germination, 111,

— glaucum, 204, 226.

— —, abscision of gonidia,
70*,

— —, capacity of germina-
tion, 344.

— —, cell-nucleus, 6.

— —, conditions of germina-
tion, 349.

— —, mycelial membranes,
21.

‚ parasitism, 370, 380.

— —, resistance of spores,
347.

—, gonidiophores, 48.

—, sclerotioid compound
sporophores, 43.

—, secretion of ferment,
355.

—, simple sporophores, 46.

—, thallus, 1.

Perichaena, 435.

— liceoides, 423, 427, 428,
435, 441, 448.

Periconia, 252.

—, formation of spores, 66.

Peridermium elatinum, 277,
282.

— —, parasitism, 368, 388,
390.

— Pini, parasitism, 388.

— —, structure of spores,
100,

Peridiola, 311, 320.

Peridium, 48, 193,
308.

—, inner, 311.

—, outer, 311.

Periphyses, 192,

Periplasm, 133.

Perithecia, 76, 187, 190, 239,
401.

275)

INDEX,

Peronospora, 138, 232.

—, abscision of spores, 72.

— Alsinearum, fertilisation,
133%

— arborescens, fertilisation,
133*.

— Arenariae, parasitism,391.

— calotheca, haustoria, 20*.

— densa, germination, 112.

— —, haustoria, 20.

— —, parasitism, 393.

—, development, 134.

—, discharge of spores, 82.

—, membrane, 12.

— nivea, haustoria, 20.

— —, parasitism, 363, 393.

— parasitica, haustoria, 20.

— —, parasitism, 359, 362.

—, parasitism, 358, 386, 391.

— pygmaea, germination,
112.

— —, haustoria, 20.

— —, parasitism, 364.

— Radii, parasitism,
364, 390, 391.

—, simple sporophores, 46,
47.

—, thallus, 1.

— Umbelliferarum, parasi-
tism, 363, 389.

— Valerianellae, 135.

— violacea, parasitism, 368,
390, 391.

— viticola, parasitism, 393.

Peronosporeae (Peronospo-
rei), 132, 183, 232, 233,
236.

—, absence of calcium, 11.

—, capacity of germination,
343, 344, 349.

—, cell-nucleus, 6.

—, cellulose-membrane, 8,

—, conditions of germina-
tion, 350,

— discharge of spores, 82.

—, formation of spores, 74,
75+

—, germination, 113.

—, haustoria, 20*.

—, mycelium, 20*.

—, parasitism, 359, 362, 386,

358,

393.

—, pleuroblastic, 20.

—, resistance of spores, 345.

—, resting state of spores,
344.

—, swarm-spores, 109.

—, thallus, 1.

Pertusaria communis, ger-
mination, ı14*.

— de Baryana, germination,
112*,

— fallax, calcium oxalate,
409.

Pertusaria lejoplaca,develop-
ment of spores, 78.

— —, germination, 114*.

—, number of spores, 79.

—, soredia, 415.

—, structure of thallus, 405.

Peziza (see also Sclerotinia),
189.

— abietina, 86.

— —, ejection of spores, 86.

—-—, structure of spores,
106.

— Acetabulum, develop-
ment of spores, 106.

— —, ejection of spores, 85.

— —, puffing of spores, 89,
92.

— —, structure of spores, 77.

— aeruginosa, colouring mat-
ter, 8.

— Aglaospora, 243.

— arduennensis, 243.

— aurantia, fatty matters,
7.

— —, structure of spores,
100,

— baccarum, sclerotium, 30,

41.

— benesuada, doubtful sper-
matia, 243*.

— bolaris, 243.

— —, germination, 115.

— calycina, development of
spores, 78.
— Candolleana, sclerotium,
30, 31, 32.
— ciborioides,
39, 41.

— confluens, 208.

— —,developmentofspores,
76, 77*.

— —, ejection of spores, 86,

— convexula, ejection of
spores, 85, 86.

— —, structure of spores,
102,

— cupularis, ejection of
spores, 85, 86.

— Curreyana, desertion of
host, 388.

— —, sclerotia, 33, 37, 41.

— Cylichnium, 243.

— —, germination, 115.

—, development of asco-
spores, 76.

— Duriaei, sclerotia, 37.

— Durieuana, 243.

— —, desertion of host, 388.

— —, sclerotia, 41.

—, ejection of spores, 89.

— Fuckeliana, 245, 254.

— —, abscision of spores,
63, 72.

— —, cell-nucleus, 6.

sclerotium,

Peziza Fuckeliana, develop-
ment of spores, 62, 78.

— —, doubtful spermatia,
243.

— —, gonidiophores, 38.

— —, resistance of gonidia,
347.

— —, sclerotia, 31*, 37, 41.

— fulgens,colouring matters,
8.

— —, mycelial strands, 22.

— fusarioides, 242.

— granulata, 215.

— —, ejection of spores, 86.

—, hairs, 59.

— hemisphaerica, structure
of spores, 58.

— —, structure of sporo-
phore, 106.

—, inception of sporophore,

49.

— melaena, development of
spores, 77.

— —, ejection of spores, 85,

— —, number of spores, 79.

— —, structure of spores,
102, 106.

— melanoloma, 215.

— nivea, development of
sporophore, 53.

— pitya, development of
spores, 76.

— —, ejection of spores, 85.

— Rapulum,mycelialstrands,
22.

— ripensis, sclerotium, 41.

— Sclerotiorum, 243.

— —, clamp-connections,19.

— —, compound sporo-
phores, branching, 51.

— —, development of spores,
78.

— —, development of sporo-
phore, 53*.

— —, ejection of spores, 87*.

— —, puffing of spores, 89.

— —, sclerotia, 30, 31*, 35,
37, 41.

— —, structure ofspores,106.

— —, structure of sporo-
phore, 58.

— scutellata, 215.

—, structure of spores, 99.

—, structure of sporophore,
58. =

— Tuba, sclerotia, 41.

— tuberosa, 243.

— —, development of spores,
73.

— —, germination, 115.

— —, sclerotia, 30.

— —, structure of spores,
106.

INDEX.

Peziza vesiculosa, ejection
of spores, 86.

——, structure of spores,
106,

Phacidiaceae (Phacidiacei),
190.

—, parasitism, 386.

Phacidium, development of
spores, 83.

—, lipoxeny, 388.

— Pinastri, development of
spores, 83,
Phalloideae (Phalloidei), 308,
309, 312, 322, 338, 340.
—, compound sporophores,
49.

— —, growth, 51.

—, conditions of germina-
tion, 352.

—, formation of spores, 63.

—, gelatinous membranes, 9,
13.

—, mycelial strands, 22, 23.

—, pseudo-parenchyma, 3.

—, secretions of calcium, 11.

Phallus, 312.

— caninus, calcium oxalate,
11*,

— —, development of sporo-
phore, 322, 323*-

— —, formation of spores,
63*.

— —, mycelial strands, 23.

— impudicus, development
of sporophore, 322, 323*-

— —, duration of growth,51.

— —, mycelial strands, 23.

Phellorinia, 327.

Phelonites strobilina, 282.

—, structure of spores, 100.

Phlyctidieae (Phlyctidiei),
164.

Pholiota, 297.

Phoma, 248, 252.

Phragmidium, 276, 277.

—, detaching of spores, 68.

—, parasitism, 393.

—, spores, 68, 98.

Phragmotrichum, spores, 68.

Phycolichenes, 402.

Phycomyces, 146, 147, 150,
152, 155.

—, discharge of spores, 83.

— microsporus, 150.

— nitens, 150.

— —, capacity of germina-
tion, 344.

— —, membrane, 8.

— —, mycelium, 146*.

— —, organs of propagation,
146*.

—, resistance of spores, 346.

Phycomycetes, 120, 132.

—, formation of spores, 74.

517
Phycomycetes, swarm-
spores, 107.
Phyllachora, lipoxeny, 388.
—, stroma, 43.
— Ulmi, 216.
— —, ejection of spores, 94.
Phyllactidium in Lichen-
thallus, 397.
Phylliscum, structure of
thallus, 413.
Phyllosticta, 252.
Phyllosticteae(Phyllostictei),

251.

Physareae (Physarei), 424,
426, 428, 430, 433, 434
439, 440, 441, 449, 451.

Physarum, 430, 434,436, 448.

— album, 441.

— aureum, 435.

— hyalinum, 435.

— leucophaeum, capillitium,
sporangium, 435*.

— macrocarpum, 448.

— psittacinum, 424, 435.

— sinuosum, 428.

— sulphureum, 435.

Physica parietina, Algae of
thallus, 397*.

— —, incrustations, 408.

— —, soredia, 416.

— —, structure of thallus,

403*, 406.

Physma, 108, 214, 231, 240,
259.

—chalazanum, Algae of

thallus, 397*.
—, structure of thallus, 412,
413.
Physoderma Butomi, 166.
— Heleocharidis, 166.
— maculare, 166.
— pulposum, 164.
— vagans, 166.
Phytophthora, 137.
—, development, 134.

— discharge of swarm-
spores, 82*,

—, formation of swarm-
spores, 75.

—, germination, 109.

— infestans, abscision of

spores, 72.

——, capacity of germina-
tion, 343.

— —, discharge of swarm-
spores, 82*.

— —, germination of gonidia,
-137*,

— —, germination of swarm-
spores, 364*.

— —, gonidia, 137*.

— —, gonidiophores, 47*.

— —, haustoria, 20.

— —, parasitism,3 59,362,385.

518

Phytophthora infestans, re-
sistance of spores, 346.

— —, simple sporophores,
47*.

— —, swarm-spores, 108*,

— —, taking up of colouring
matter, 14.

— omnivora, 135.

— —, parasitism, 359, 365,
385.

—, parasitism, 367, 389, 392.

—, simple sporophores, 47.

Pietra fungaja, 42.

Pilacre Petersii, 335.

Pilaira, 150, 152.

—., discharge of spores, 83.

Pileus, 287.

— in Hymenomycetes, 48.

Pilobolus, 152, 155.

— anomalus, 150.

— —, detaching of sporangia,
83.

—, conditions of germina-
tion, 350.

— coloured fatty matters, 7.

— crystallinus, 150.

— —, abjection of sporangia,
72, 83.

—, formation :of spores, 74,
75+

—, membrane, 12.

—, mode of life, 357.

— oedipus, 163.

— —, abjection of sporangia,
72*, 83.

——, resistance of spores,
346.

—, structure of spores, 106. .

Piptocephalideae (Piptoce-
phalidei), 149, 151, 153.
Piptocephalis, 147, 149, 153,

155.
—, formation of spores, 67.
— Freseniana, 150, 153*.
— —, conjugation, 149*.
— —, haustoria, 20.
—, parasitism, 360, 363, 385.
Pistillaria hederaecola, scle-
rotia, 42.
— micans, sclerotia, 42.
Pits, 13.
— in spore-membrane, 100.
Pityriasis versicolor, 376.
Placodium, 223.
—, calcium oxalate, 409.
— cartilagineum, incrusta-
_ tions, 409.
—, distribution of Algae in
thallus, 404.
—, structure of thallus, 404,
Plasmodia, 423.
—, movement, 449.
—, nutrition, 451.
—, phenomena of life, 449,

INDEX.

Plasmodiophora, 444.
— Brassicae, 448.

Plastids, 7.

Plectopsora, structure of
thallus, 412, 413.

— botryosa, structure of

thallus, 414*.
Pleomorphism, 126, 238.
Pleospora, 186, 191, 200,

235, 239, 245, 248, 271.
— Alternariae, 230, 255.

— —, development of pyc-

nidia, 247*.

— Clavariarum, 244.
—, ejection of spores, 95.
—, formation of gonidia,

66.

— herbarum, 220, 229, 230,

247, 255.

— —, compound spores, 98.
— —, development of spores,

79.

— —, ejection of

95”. an
— —, germination, 114.

— polytricha, 245, 247.
— sarcinulae, 230.
—, sclerotioid | compound

sporophores, 43.
Pleurococcus in Lichen-

thallus, 397.

Pleurostoma, 191.
Pleurotus, 297.

Podaxon, 317, 318.

— carcinomatis, capillitium-

threads, 318*.

— pistillaris, 318*.
Podetia (podetium), 222,402.
Podosphaera, 198, 201, 233,

235, 236, 237.

— Castagnei, development

of spores, 79.

— —, development of sporo-

phores, 201*, 226*.

— —, haustoria, 19*,

— pannosa, 226*.
Pollinaria, 305.

Polyactis, 252.

Polyblastia, 223.

— rugulosa, Algae of thallus,

409.

— —, hymenial Algae, 400,

401.

— —, structure of thallus,

400,

Polydesmus, 229.

— exitiosus, parasitism, 362.
—, spores, 68.

Polyphagus, 169.

— Euglenae, 162*,

— —, parasitism, 361.

— parasiticus, 164.

—, Swarm-spores, 107.
Polyplocium, 337.

spores,

Polyporeae (Polyporei), 288,
333, 337. ;
—, annual layers in com-
pound sporophores, 57.
—, duration of growth in
compound sporophores,
51.

Polyporus, 288, 301, 303,
307.

— abietinus, mycelial mem-
branes, 22. :
— annosus, parasitism, 384.
— —, structure of sporo-

phore, 57.
— borealis, 335.
— —, parasitism, 384.
—, cellulose, 13.
—, clamp-connections, z.
— destructor, abjection of
spores, 73.
— dryadeus, parasitism, 384.
— fomentarius, cellulose, 8.
— —, membranes, 12.
— —, periodic growth of

compound sporophores,
57.

— —, structure of sporo-
phore, 58.

— fulvus, 307.

— —, parasitism, 384.

— —, structure of sporo-
phore, 58.

—, growth of compound
sporophore, 50, 57.

— hirsutus, hairs, 59.

— hispidus, hairs, 59.

— igniarius, 303, 307.

— —, cellulose, 8.

— —, parasitism, 384.

— —, periodic growth of
compound sporophore, 57.

— lucidus, structure of spo-
rophore, 59*.

—, membranes, 12.

— mollis, parasitism, 384.

— obvallatus, 337.

— officinalis, cellulose, 8.

— —, membranes, 12.

— —, secretion of resin, Io.

— ptychogaster, 334, 335.

— Ribis, periodic growth,
57.

— sulphureus,
384.

— tuberaster, mycelium, 42.

— umbellatus, 304.

— vaporarius, parasitism,
384.

— versicolor,membranes, ı2.

— volvatus, 337.

— zonatus, membranes, 12.

— —, Periodic growth, 57,

Polysaccum, 309, 326, 327.

—, formation of spores, 63.

parasitism,

Polystigma, 191, 200, 235,
236, 239, 240, 241, 258,
259, 285.

— fulvum, 199, 2135.

—, gelatinous membranes, 9.

—, lipoxeny, 388, 389.

—, parasitism, 386.

— rubrum, 199, 215, 224,
226, 240.

—, conditions of germination,
350.

— —, parasitism, 362.

— stellare, mycelial strands,
22, 23.

—, stroma, 43.

—, structure of sporophore,
57.

Pore, 191.

Pores in Polyporee (Poly-
porei), 288.

Poronia, 244.

Precursors of ascocarps in
Ascomycetes, 244.

Predisposition for parasites,
359.

Primordium of the myce-
lium, 110, 178.

— of sporophore, 199, 215,
218.

Procarpium (procarp), 120.

Promycelium, 111, 177.

Prosporangium, 163.

Protagon-mixtures, 300.

Prothallium, 121.

Protococcus in Lichen-
thallus, 397*.

Protomyces, 132, 171.

—, capacity of germination,
349.

—, germination, 109.

—, ejection of spores, 85.

—, formation of spores, 61.

— macrosporus, 171.

— —,cellulose-membrane, 8.

——, conditions of germina-
tion, 351. .

— —, development of spores,
172.

— —,ejection of spores, 89,
91.

— —, parasitism, 363, 365,
386, 389.

— —, resting spores, 172*.

— —, structure ofspores,106.

— Menyanthidis, 166.

— pachydermus, 172.

—, resting state of spores,
345. .

Protomyxa aurantiaca, 446.

Protoplasm, 6.

— in Bacteria, 455.

— in Mycetozoa, 422, 423,
425, 426,

Protothallus, 405.

INDEX.

Protozoa, 475.

Psalliota, 291, 297.

Pseudo-lichens, 416.

Pseudo-parenchyma,3,5,405.

Pseudo-peridia, 275.

Pseudopodia, 423, 426.

Pseudospora, 447.

Psora, structure of thallus,
404.

Psoroma, Algae of thallus,
409.

— gypsaceum, incrustation,
408.

— lentigerum, secretion of
calcium, 11.

— —, calcium oxalate, 408.

— sphinctrinum, Algae of
thallus, 404.

—, structure of thallus, 404.

Pterula, 29.

Ptychogaster albus, 335.

Puccinia, 279, 282.

— Aegopodii, 285.

— Alliorum, 277.

— Anemones, 277.

— —, parasitism, 393.

— Asari, 285.

— Berberidis, 279, 283, 284.

— Caricis, parasitism, 387.

— coronata, parasitism, 387.

— —, structure of spores,
100,

—, detaching of spores, 68,

—, Falcariae, 279.

— —, parasitism, 387.

—, formation of spores, 62*.

— fusca, 277, 281.

— Galiorum, 277.

— graminis, development of
aecidia, 275*, 276*.

— —, capacity of germina-
tion, 345, 348.

— —, development of spores,
62*,

— —, germination,
280%,

— —, germ-pores, 100.

— —, parasitism, 387, 389.

— —, rest of spores, 345.

— —, spermogonia, 276*.

— —, structure of spores,
101.

— Malvacearum, 284.

— Moliniae, parasitism, 387.

— Pimpinellae, parasitism,
387.

— Pruni, 285.

— reticulata, structure of
spores, 100.

— Rubigo vera, 283.

— —, germination, 280*.

— —, parasitism, 387, 389.

—, spores, 68, 98.

—, structure of spores, 100.

110*,

519

Puccinia suaveolens, 277.

— —, parasitism, 359.

— Tragopogonis, parasitism,
387, 391.

— Violarum, parasitism, 387.
Putrefactive processes in-
cited by Bacteria, 481.
Pycnidia, 49, 225, 239, 246.

—, large-pored, 248.

—, small-pored, 248.

Pycnis sclerotivora, 247.

Pycnochytrium, 167.

Pycnogonidia, 225, 239, 246.

Pycnospores, 225, 239, 246.

Pyrenocarp, 187.

Pyrenomycetes,
200.

— as Lichen-fungi, 396.

—, development of spores,
78.

—, ejection of spores, 91, 97.

—, hyphal weft, 4.

—, number of spores, 79.

—, stromata, 50.

—, structure of ascus, 96.

Pyrenula, 192, 223.

— minuta, 246.

—nitida, structure of
thallus, 411.

— —, thallus, 402.

— olivacea, 246.

Pyronema, 190, 198, 224,
231, 234, 237, 239.

— confluens, 208.

— —, development of sporo-
phore, 209*.

Pythium, 234.

— de Baryanum, 135, 137.

— —, parasitism, 382.

—, development, 135, 137.

—, discharge of spores, 82.

— endophytum, 139.

— gracile, fertilisation, 133*.

— intermedium, 137.

— —, parasitism, 382.

— megalacanthum, parasit-
ism, 382.

—, mode of life, 132.

—, parasitism, 359, 363, 382,
389, 392.

— proliferum, 135.

— —, rest of spores, 345.

—, rest of spores, 345.

—, swarm-spores, 107.

— vexans, 135, 232.

186, 187,

Quaternaria, 218.
—, discharge of spores, 97.
Queletia, 318.

Racodium cellare, 22.
—rupestre, structure of
thallus, 411.

520

Ramalina, soredia, 415.

Reaction of host on parasite,
366.

Receptaculum, 17, 48, 188,
312.

Recurrent fever, 486, 488.

Reduction in the course of
development, 125.

Resin in Boletus, 15.

Resin-excretions, 10.

Resin-flux, 384.

Resistance in spores, 343.

— in Bacteria, 476.

Resting gonidia, 144.

— mycelia, 230, 245.

— sporangia, 144.

— spores, 345.

— — in Bacteria, 460.

— states, transitory in My-
cetozoa, 427.

Reticularia, 431, 440.

— umbrina, 439.

Rheotropism in plasmodia,

449.

Rhipidium, 144.

Rhipidonema, structure of
thallus, 414.

Rhizidieae (Rhizidiei), 162,
169, 170.

Rhizidium, 164, 165.

Rhizines, 402.

Rhizocarpon, structure of
thallus, 405.

Rhizoids, 45, 59, 402.

Rhizomorpha fragilis, 28.

—,, parasitism, 383, 384.

— subcorticalis, 28.

— subterranea, 28.

Rhizophydium, 164.

Rhizopoda, 444, 475.

Rhizopogon, 308.

—, formation of spores, 63.

Rhizopus, 152.

— nigricans, 152, 154.

— —, conjugation, 148*.

—, discharge of spores, 83.

Rhytisma, 186, 240.

—acerinum, ejection of
spores, 87, 92.

— Andromedae, 224.

— —, germination, 111*.

— —, parasitism, 358, 393.

— —, structure ofspores,102.

—, asci, 76.

—, conditions of germina-
tion, 350,

—, lipoxeny, 388.

—, parasitism, 389.

—, stroma, 43.

— —, structure, 58.

—, structure of sporophore,
57.

Rind of compound sporo-
phore, 58.

INDEX.

Rind (rind-layer) of Lichen-
thallus, 403.

Roccella, Algae of thallus,
409.

— fusiformis, incrustations,
408.

— —, calcium oxalate, 409.

— —, structure of thallus,
406,

— Montagnei, 246.

—, soredia, 415.

—, structure of thallus, 404,
406.

Rod-like forms in Bacteria,

458.
—, gonidia, 331.
Roesleria hypogaea, dis-

charge of spores, 96.
Roestalia, 388.
Root-hairs, 45, 54, 59.
Rosellinia Aquila, structure
of ascus, 96.
— quercina, 215.
— —, mycelium, 42.
Rotting in orchard fruit,

379.

Rozella, 169, 444.

—, parasitism, 368, 395.

— septigena, parasitism, 395.

Russula, 297, 304.

— adusta, 298.

—, calcium oxalate, 11.

— foetens, var. lactiflua, 300.

— integra, 298.

— —, structure of sporo-
phore, 58.

— olivacea, 298.

—, pseudo-parenchyma, 3.

Rutstroemia (see Sclero-
tinia), 41.

—., ejection of spores, 86.

Ryparobius, 208.

Saccharomyces,
267, 270.

— albicans, 267.

— —, parasitism, 377.

— apiculatus, 271, 272.

— —, mode of life, 357.

—, cell-nucleus, 6.

— Cerevisiae, 267.

— „resistance to effects of
heat, 347.

— —, sprouting, 4*, 267*.

— —,swelling of membrane,
10,

—, conditions of vegetation,
353.

— ellipsoideus, 267.

— —, formation of spores,
268*.

—, germination, 114.

— glutinis, 272.

— mesentericus, 358.

132, 263,

Saccharomyces, Mycoder-
ma, 267, 268, 269, 358,
377.

— Pastorianus, 267.

—, pleomorphism,
270.

—,secretion of ferments,
355.

—, thallus, 5.

Saccobolus,
spores, 92.

—, structure of spores, 102.

Sagedia aenea, 246,

— callopisma, 246.

— carpinea, 246.

— netrospora, 246.

— Thuretii, 246.

— Zizyphi, 246.

Salts of iron in Lichen-thal-
lus, 408.

Sap-cavities (vacuoles), 6.

Saprolegnia, 143.

—, discharge of spores, 82.

—, formation of spores, 74.

— hypogyna, 141, 142.

— monoica, 141.

—, parasitism, 359, 393.

—, simple sporophores, 46.

—, sporangia, 46.

—, swarm-spores, 107, 108.

Saprolegnieae (Saprolegniei),
141, 232.

—, capacity of germination,
343.

—, cell-nucleus, 6,

—, cellulose-membrane, 8.

—, discharge of spores, 82.

—, parasitism, 375, 395.

—, resistance of spores, 345.

—, rest of spores, 344.

—, simple sporophores, 46.

Saprophytes, 356, 357, 480.

—, facultative, 356.

—, obligate, 356.

Sarcina, 473.

— ventriculi, 459.

Sarcinula, 229.

Sarcogyna, numberof spores,
79.

Scales on compound sporo-
phores, 59.

Schizomycetes, 454.

Schizonella, 176.

Schizopbyllum, 302.

Schizophytes, 474, 476.

Schizosiphon in Lichen-
thallus, 398.

Sclerangium, 315.

Scleroderma, 309, 311, 313,
315.

—, formation of spores, 63.

—, mycelial strands, 23.

Sclerosis of membranes, 9.

Sclerotia, 18, 30,

alleged,

ejection of

Sclerotia, development, 34.

—, further development, 37.

—, gelatinous membranes,
10.

—, hyphal weft, 3.

— in Mycetozoa, 427, 428.

—, membranes, 12.

—, pseudo-parenchyma, 3.

—, resting state, 37.

Sclerotinia, 41, 200, 260.
(See also Peziza.)

— ciborioides, organs of at-
tachment, 21.

— —, parasitism, 380.

— —, resistance of spores,
346.

—, development of spores,
78.

— Fuckeliana, 219, 224, 238,
251.
— —, compound
phores, 38*.
— —, conditions of ger-
mination, 350, 351.

— —, germination, 113.

— —, gonidiophores, 48.

— —, organs of attachment,
21.

— —, parasitism, 380.

— —, sclerotia, 31*, 34, 37,
38*, 39.

—, gelatinous membranes, 9.

—, lipoxeny, 388.

—, membranes, 12.
—, organs of attachment re-
sembling haustoria, 21.
—, parasitism, 359, 360, 380,
389, 392.

—, sclerotia, 30, 34, 39-

— Sclerotiorum, 200, 218,
224.

sporo-

— —, compound sporo-
phores, development, 53*,
219*.

— —, conditions of ger-
mination, 351.

— —,ejection of spores, 87*.

— —,germination of sclero-
tia, 38, 39.

— —, organs of attachment,
21.

— —, parasitism, 359, 380.

— —, sclerotia, 30, 31*, 34,
37, 39.

— tuberosa, 243, 260.

— —,organs of attachment,
21.

Sclerotium, 40.

— areolatum, 41.

— Clavus, 41.

— Cocos, 42.

— compactum, 41.

— complanatum, 42.

— cornutum, 42.

INDEX.

Sclerotium crustuliforme,42.

— Cyparissiae, 41.

— durum, 251.

— echinatum, 41, 238.

— fulvum, 41.

— lacunosum, 42.

— laetum, 42.

— muscorum, 32.

— mycetospora, 42.

— pubescens, 42.

— Pustula, 41.

— roseum, 41.

— scutellatum, 42.

— Semen, 41.

— stercorarium, 32, 42.

— stipitatum, 42.

— sulcatum, 41.

— truncorum, 42.

— vaporarium, 42.

— varium, 41.

— vulgatum, 42.

Scytonemain Lichen-thallus,
397*, 398.

Sebacina incrustans, 306.

Secotieae (Secotiei), 310,313.

Secotium, 310, 313, 337-

— erythrocephalum, 337.

— —, compound sporophore,
310*.

Semen, 130.

— multiplex, 98.

Sepedonium, 245, 252.

Septicaemia, 486.

Septoria, 252.

Sexual organs, 49, 233.

—, assumed in Basidiomy-
cetes, 332.

Sexuality, 120.

— in Ascomycetes, 237.

Short rods (Bacteria), 458.

Silk-worms, diseases in, 486,
489.

Simblum, 326.

Simple sporophores, 46.

— —, germination, 114*.

— —, structure of thallus,

404.

Sirosiphon in Lichen-thal-
lus, 398.

Solorina crocea, Algae of
thallus, 409.

— saccata, Algae of thallus,
409.

— —, incrustation, 408.

Sordaria, 191, 198, 199, 210,
235, 243, 260.

— Brefeldii, attachment of
spores to ascus, 88.

—, conditions of germina-
tion, 350.

— coprophila, 243.

— —, structure of spores,
103.

— curvula, 243, 261.

521

Sordaria curvula, capacity
of germination, 344.

— decipiens, 243.

—, ejection of spores, 86, 88,
91*.

— fimicola, 210, 261.

— fimiseda, 192.

— —, capacity of germina-
tion, 343.

— —, development of spores,
78.

— —, ejection of spores, 85,
92.

— —, germ-pores, rot.

— —, number of spores, 79.

— —, structure of spores,
103, 104*.

—, germination, III.

— minuta, 243, 261.

—-—, ejection of
g1*.

—, mode of life, 357.

—, number of spores, 79.

— pleiospora, number of
spores, 79.

—, structure of spores, 103,
106,

Soredia, 244, 401, 415.

Soredia-heaps, 416.

Sorosporium, 175, 176.

— Saponariae, 172, 179.

— —, parasitism, 391.

— —, rest of spores, 345.

Sorus, 167, 416.

Spathulea, 189.

Spermatia, 199, 211*, 239,
240, 257, 276*.

—, supposed in Basidiomy-
cetes, 333.

—, doubtful, 242.

Spermogonia, 199, 211*, 239,
240, 241, 257, 276*, 401.

Sphacelia, 227, 252.

Sphacelotheca, 173.

— Hydropiperis, compound
sporophores, 174*.

Sphaerella Plantaginis, 220.

Sphaeria discretia, fatty
matters, 7.

— eutypa, fatty matters, 7.

— inquinans, ejection of
spores, 95.

— Lemaneae, 214.

— —, ejection of spores, 85,

spores,

94-

— obducens, development
of spores, 79.

— —, ejection of spores, 95.

— oblitescens, 245.

— praecox, germination,115.

— —, structure of spores,
104.

— Scirpi, development of
spores, 79.

522

Sphaeria Scirpi, ejection of
spores, 85, 93*.

— —, structure of spores,
99*, 102, 103.

— Stigma, fatty matters, 7.

Sphaeriaceae (Sphaeriacei),
ejection of spores, 85.

—, formation of gonidia, 66.

—, structure of spores, 102.

Sphaeriae compositae, 186.

Sphaerobolus, 326, 329, 330,

331, 332, 340.
—, coloured fatty matters,

7.

—, mycelial strands, 22.

—, stellatus, 328.

Sphaeromphale, 192.

Sphaerophoron, 193.

— coralloides, development
of spores, 78.

— —, discharge of spores,
96*.

— —, gonidia, 398*.

— —, incrustations, 408.

—, discharge of spores, 96*,

97.

—, structure of thallus, 404,
406.

Sphaeropsideae (Sphaerop-
sidei), 251, 252.

Sphaeropsis, 252.

Spheconisca, 416.

Sphere-yeast, 156.

Sphyridium, 200.

— fungiforme, 221.

— placophylium, 221.

Spicaria, 245.

Spilonema, 242.

—, structure of thallus, 412.

Spilosphaeria, 252.

Spinellus, 152.

Spiral forms in Bacteria,458.

Spirillum, 456, 458, 459,
473.

— amyliferum, 455, 461.

Spirochaete, 458, 459.

— Obermeyeri, 488.

Spora, 128.

Sporae cellulosae, 98.

— compositae, 98.

— multiloculares, 98.

Sporangia (sporangium), 45,
73, 130, 319.

— in Mycetozoa, 429, 434.

Sporangiola, 152.

Spore, 130.

Spore-development (see also
Spore-formation), 60.

—, acrogenous, 61.

— by free cell-formation, 61.

— —, cell-division, 61.

— intercalary, 61.

Spore-formation, branched
concatenate, 66.

INDEX.

Spore-formation, by cross-
septation, 67.

—, endogenous, 73.

— in Bacteria, 460, 465.

— in Mycetozoa, 429.

—, simple concatenate, 66.

—, simultaneous, 63.

—, successive, 63.

—, sympodial, 65.

Spore-germination, 109.

Spore-groups, 99.

Spore-heads, 63.

Spore-initial cells, 98.

Spore-membrane, chemical
properties, 104.

Spore-membranes, 83.

Spore-mother-cells, 48, 60,
98.

Spore-primordia, 98.

Spore-receptacles, 48.

Spores, 45, 59, 121,
128.

—, abjection, 68, 72.

—, abjunction, 61.

—, abscision, 68.

—, appendages of, 102.

—, capacity of germination,
343.

—, compound, 98.

—, conditions of germina-
tion, 349.

—, delimitation, 61, 68.

—, detaching, 68.

—, discharge, 82.

—, fatty matters, 7.

—, germination, 109.

— of Bacteria, 461.

— of Mycetozoa, 421, 440,

124,

441.
—, pluricellular, 98.
—, resistance, 346.
—, resting state, 345.
—, ripeness, 68,
—, septate, 68, 98.
—, structure, 99.
Sporidesmieae (Sporidesmii),

Sporidesmium, 68, 229.

—, spores, 68.

Sporidesms, 99.

Sporidia, 111, 130, 177.

—, capacity of germination,

343.

—, whorl of cylindrical or
subulate (Kranzkörper),
177.

Sporoblasts, 99.

Sporocadus, 252.

Sporocarpium (sporocarp),
121, 185, 239.

Sporodinia, 147, 148, 149,
150, 151, 152.

— grandis, 147, 150, 154.

—, resistance of spores, 346.

Sporodinia, resting time of
spores, 345.

Sporogenous layer (hyme-
nium), 49.

Sporophore, 45.

— in Mycetozoa, 429.

Sporophyte, 121.

Sporormia fimetaria, spores,
99.

Sporula, 130.

Spread of parasite in host,
389.

Sprout-gemmae, 155.

Sprout-germination, 110.

Sprouting Fungi, 4*, 5, 60.

—, form, 4*, 5, 267.

—, germination, 114.

— —, in Ustilagineae, 177.

—, growth, 155.

—, mucilage, 9.

Spumaria, 436, 440.

Spumella vulgaris, 475.

Steganosporium, 252.

Stemoniteae (Stemonitei),
427, 4345 439, 441.

Stemonitis, 423, 431, 432,
433, 438, 440.

— ferruginea, formation of
sporangia, 432*.

— fusca, 427.

Stephensia, 196.

Stereocaulon,
thallus, 410.

—, podetia, 402.

— ramulosum,
thallus, 397*.

Stereum (see also Thele-
phora), 303, 304.

— hirsutum, development of
sporophore, 53*.

— —, fatty matters, 7.

— —, parasitism, 384.

— —, periodic growth, 57.

— —, structure of sporo-
phore, 57, 58.

— rubiginosum, 303.

— tabacinum, 303.

Sterigma, 61.

Sterigmata in spermatia, 240.

Sterigmatocystis, 206, 256.

—, parasitism, 369.

Stichococcus in
thallus, 397.

Sticta, Algae of thallus, 409.

— aurata, incrustation, 408.

— fuliginosa, structure of
thallus, 403%.

— glomulifera,
thallus, 409.

—, incrustation of thallus,
408,

— pulmonacea, thallus, 187*.

—-—, structure of thallus, .
406, ;

Algae of

Algae of

Lichen-

Algae of

Sticta, structure of thallus,
406.
Stictina,Algae of thallus,409.
Stictosphaeria, 191,218, 241.
—, discharge of spores, 97.
— Hoffmanni, 258.
Stigmatea, 244.
Stigmatomma cataleptum,
origination of thallus, 400.
— —, hymenial Algae, 400,
401.
Stigmatomyces Baeri, 263.
— —, development, 263*.

— Muscae, development,
263*,
Stigonema in Lichen-thallus,

398.

Stilbospora, 252.

—, spores, 68.

Stilbum, 29, 252, 334.

Stipes in sporophore of
Hymenomycetes, 287.

Stratum corticale, 403.

— gonimon, 417.

— medullare, 403.

Striation of spore- mem-
brane, roo.

Stromata, 48, 186.

Stylospores, 154, 225, 239,
246, 279.

Stysanus, 252.

Suberisation of membranes,

9.

Subhymenial layer or tissue,
301.

Sulphur in Bacteria, 455,

471.

Supply of food, a condition
of germination, 351.

Suspensor in zygospores,
148.

Swarm-cells, 107.

— in Mycetozoa, 422.

Swarm-spores, 60, 107, 129.

—, capacity of germination,
343.

—, discharge, 82.

—, resistance, 346.

Symbiosis, 356.

Synalissa, structure of thal-
lus, 413, 414*.

— symphorea,
thallus, 397*.

Syncephalis, 146, 153, 154.

— curvata, 150.

—, formation of spores, 67,
117.

— furcata, 153.

—, haustoria, 20.

— nodosa, 149, 150.

— parasitica, 360, 363, 385.

—, secondary mycelium, 45.

Synchytrium, 162, 167, 168,
169, 444.

Algae of

INDEX.

Synchytrium, rest of spores,
345.

— aureum, 160.

— —, rest of spores, 345.

—, capacity of germination,

349.

— Oenotherae, 168.

—, rest of spores, 345.

— Stellariae, 168, 169.

— —, propagation, 168*.

— Succisae, 169.

— Taraxaci, 168.

— —, rest of spores, 345.

Synechoblastus, 198.

—, structure of thallus, 412.

Systematic arrangement of
Fungi, 132.

Syzygites, 151.

— ampelinus, 151.

Taphrina, 265.

—, germination, 115.

Tarichium, 159.

Teeth, caries, 472.

Tela contexta, 5.

Teleutogonidia, 281.

Teleutospores, 279, 282, 339.

—, resting state, 345.

Terfezia, 195.

Terminology of Fungi, 128,
130.

Tetrachytrium triceps, 170.

Thalloidima candidum, cal-
cium oxalate, 409.

— —, structure of thallus,
404.

Thallus, 1.

—, branching, 1.

—, crustaceus, 402.

—, differentiation, 17.

—, fertile (stroma), 186.

—, filamentosus, 401.

—, foliaceus, 401.

—, frondosus, 401.

—, fruticulosus, 401.

—, lepodes, 402.

—, placodes, 401.

—, thamnodes, 401.

Thamnidium, 152.

—., discharge of spores,82,83.

— elegans, 150.

Thamnolia,incrustation,408.

—, structure of thallus, 406.

— vermicularis, calcium ox-
alate, 409.

Thamnomyces, 186.

—, branching, 51.

Thecae (asci), 76.

Thecaphora, 176.

— hyalina, 177.

— Lathyri, 177, 179.

Thecaspores, 129.

Thelephora crocea, mycelial
membranes, 22.

523

Thelephora hirsuta, mem-
branes, 12.

——, mycelial membranes,
22.

—, membranes, 12.

— mesenterica, gelatinous
membranes, 13.

—, mycelial membranes, 22.

— Perdix, 307.

— —, parasitism, 384.

— setigera, mycelial mem-
branes, 22.

— suaveolens,mycelial mem-
branes, 22.

Thelephoreae (Thelephorei),
288, 333, 338.

—, mycelial membranes, 22.

Thelidium minutulum, 224.

— —, Algae of thallus, 409.

— —, germination, 399*.

— —, origin of thallus, 400.

— —, perithecia, 190*.

— —, structure of thallus,
410*.

Thermotropism of plasmo-
dia, 450.

Thrush (aphthae), 377.

Thyrea pulvinata, structure
of thallus, 414*.

—, structure of thallus, 413.

Tilletia, 172, 174, 177, 178,
180, 181.

— Caries, 179.

— —, capacity of germina-
tion, 344.

— —, germination, 177*.

— —, parasitism, 385.

— —, resistance of spores,
346.

—, parasitism, 367.

Tinder-fungus, 3.

Tinea (herpes), 376.

Tissue, hymenial, of Léveillé,
302.

—, intralamellar (trama),
301.

—, subhymenial, 301.

Tolyposporium Junci, 177.

Torula, 252.

Trama, 301, 309.

Trametes Pini, 301, 303,
304, 307.

— —, duration of growth, 5 1.

— —, membranes, 12.

— —, mycelial membranes,
22.

— —, parasitism, 304.

— —, periodical growth, 57.

— radiciperda, secretion of
ferment, 355.

— —, parasitism, 384.

Transmutation of host, 395.

Tremella, 305.

— Cerasi, 306, 331.

524

Tremella, foliacea, 306.

—, formation of spores, 62.

—, gelatinousmembranes,13.

— mesenterica, 331.

— violacea, 306.

Tremellineae (Tremellini),
271, 287, 288, 298, 301,
303, 305, 329, 33T, 338.

—, conditions of germina-
tion, 350.

—, fatty matters, 7.

—, gelatinous membranes, 9.

—, gemmae, 60, 61.

Tremellodon, 288, 305.

— gelatinosus, hair-forma-
tions, 59.

Trentepohlia in Lichen-thal-
lus, 397, 398*.

Trichia, 431, 433, 435, 437,
4395 440.

— chrysosperma, 438, 440.

— —, capillitium, spores,
437%.

— clavata, 434.

— fallax, 431, 437, 438, 439,
441.

— —, capillitium,
437*.

— furcata, 441.

— pyriformis, 441.

— rubiformis, 448.

— Serpula, 434.

— varia, 434, 438, 441, 448.

— —, germination, swarm-

cells, 422*,
Trichiaceae (Trichiacei),

427, 441.

Trichiae, 436.

Trichogyne, 198, 209, 213,
215, 234, 237.

Trichophyton
parasitism, 376.

Trichothecium roseum, pa-
rasitism, 380.

— —, resistance of spores,
346.

—, spores, 68.

Triphragmium, 281, 282.

— echinatum, parasitism, 358.

——, structure ofspores, 100.

—, spores, 98.

— Ulmariae, parasitism, 358.

Trophoplasts, 7.

Trophotropism in plasmodia,
449.

Truffles, 195.

—, glycogen, 6.

Tube-germination, rro.

- Tuber, 195.

— aestivum, 195.

— —, development of spores,
80.

—-—, structure of spores,
100.

spores,

tonsurans,

INDEX,

Tuber, asci, 76.

— brumale, development of
spores, 80*.

—, conditions of germina-
tion, 352.

— dryophilum, 195.

— excavatum, 195.

— melanosporum, 195.

— —, developmentof spores,
80.

— —,structure ofspores, 100.

— mesentericum, 195, 196.

—, number of spores, 79.

— rapaeodorum, 195, 196.

— rufum, compound sporo-
phore, 196*.

Tuberaceae (Tuberacei),193,
195.

—, clamp-connections, 19.

—, discharge of spores, 97.

—, hyphal weft, 3.

Tubercularia, 252.

— vulgaris, 244.

Tubuli in sporophore of
Polyporeae, 288.

Tubulina (Tubulinae), 448.

—, experiments in germina-
tion, 421.

Tubulus of perithecia of
Pyrenomycetes, 191.

Tuburcinia, 175, 176, 177.

— Trientalis, 178, 180, 181.

— —, capacity of germina-
tion, 345, 349.

— —, parasitism, 365, 391.

— —, rest of spores, 345.

Tulostoma, 287, 326.

—, capillitium, 12.

— mammosum, basidia, 3 10*,

—-—, compound sporo-
phore, 327*.

— pedunculosum, sclerotia,
42.

Tympanis, 245.

— conspersa, spermogonia,
240*.

— —, number of spores, 79.

— saligna, number of spores,

79.
Typhula, 329.
— caespitosa, sclerotium, 41.
—, clamp-connections, 2.
— erythropus, 41.
— Euphorbiae, 33, 41.
— graminum, 33, 41.
—, growth of compound spo-
rophore, 52.

— gyrans, inception of
sporophore, 49.

— —, gelatinous membranes,
9

— —, membranes, 12.
—-—,sclerotium, 30, 33*,
34, 35) 37, 39, 42.

Typhula gyrans, lactea, scle-
rotium, 41.

— phacorrhiza, sclerotium,
33%, 37,42

— Todei, sclerotium, 41.

— variabilis, development of
sporophore, 52.

— —, sclerotium, 30, 33, 345
37, 38, 42.

Ulothrix in Lichen-thallus,
397.

Umbilicaria pustulata,growth
in thickness of thallus, 407.

—, number of spores, 79.

Uncinula spiralis, 225.

Urceolaria cinerea, structure
of thallus, 405.

— scruposa, calcium oxalate,

409.

Uredineae (Uredinei), 120,
132, 274, 287.

—, aecidia-forming, 274.

—, capacity of germination,
343, 349.

—, coloured fatty matters, 7.

—, conditions of germina-
tion, 350.

—, germination, 113.

—, germ-pores, IoT.

—, gonidiophores, 50,

—, haustoria, zo.

—; parasitism, 359, 361, 363,
366, 367, 386, 387, 389,
390, 393-

—, spores, abscision, 71*,

— —, resistance, 346.

— —, rest, 344.

— —, structure, 100, 106.

—, structure of sporophore,

57.

—, tremelloid, 274, 283, 339.

Uredo, 279.

— Symphyti, 282.

Uredo-layer, 279.

Uredogonidia, 281.

Uredospores, 279.

—, capacity of germination,
343.

—, formation, 62.

—, germination, 111.

—, structure, Ioı*,

Urocystis, 172, 175, 177.

— occulta, 180.

— —, capacity of germina-
tion, 344.

— —, parasitism, 391.

—, structure of spores, 104.

— Violae, 178, 181.

Uromyces, 281, 282.

— appendiculatus, germina-
tion, 361*.

— —, germination of spo-
ridia, 364*.

Uromyces appendiculatus,
parasitism, 387.

— Belienis, 279.

— Cestri, 279.

— Dactylidis,parasitism, 387.

— Phaseolorum, 281.

— — parasitism, 387, 389.

— Pisi, parasitism, 368, 388,
391.

— Scrophulariae, 279.

— scutellatus,parasitism, 368.

—, spores, 98.

— —, detaching, 68.

— —, formation, 62.

— tuberculatus, parasitism,
358.

— Viciae Fabae, 277.

Usnea barbata, Algae of
thallus, 398*.

— —, chemical properties,
407.

— —, Incrustation, 408.

— —, soredia, 415.

— —, structure of thallus,
402*.

— —, thallus, 187*.

—., structure of thallus, 404,
405, 406.
Ustilagineae (Ustilaginei),
120, 132, 172, 176, 179.
—, capacity of germination,
344.

—, conditions of germina-
tion, 350.

—, haustoria, 19.

—, parasitism, 359, 362, 364,
367, 385, 390, 391, 393.

—, spores, rest, 345.

— —, structure, 100.

Ustilago, 174.

— antherarum, 179.

— Carbo, 177, 179, 180, 181.

— —, capacity of germina-
tion, 344.

— —, conditions of germina-
tion, 349. _

— —, germination, 178*.

— —, parasitism, 367.

— —, resistance of spores,
346.

— Cardui, 177.

— Crameri, capacity of ger-
mination, 344.

— destruens, 177, 179, 180.

— —, capacity of germina-
tion, 344.

— —, conditions of germina-
tion, 349.

— —, resistance of spores,
346. .

— flosculorum, 177.

— hypodytes, 172, 175.

INDEX.

Ustilago flosculorum, parasi-
tism, 391.

— Ischaemi, 175.

— —, formation ofspores,68.

— Kolaczeckii, capacity of
germination, 344.

— Kühniana, 177, 179.

— longissima, 173, 179, 183.

— —, germination, 178*.

— Maidis, 179, 181.

— olivacea, 173.

— Rabenhorstiana, capacity
of germination, 344.

— receptaculorum,
ture of spores, 102.

— Tragopogonis, 172, 182.

— —,, development of spores,
175*.

— —, germination, 178*.

— —, parasitism, 391.

— Tulasnei, capacity of ger-
mination, 344.

— utriculosa, 177.

— Vaillantii, 177, 179.

Ustulina, 186, 218, 244, 248,
260.

Uterus, 308.

struc-

Vacuoles (sap-cavities), 6,
424.

Valsa ambiens, 258.

— —, number of spores, 79.

— nivea, spermogonia, 240*.

— —, number of spores, 79.

— salicina, number of spores,

79+
—, structure of spores, 102.
Valseae (Valsei), 191, 192.
—, discharge of spores, 97.
Vampyrella, 447, 453.
— pendula, 447.
— Spirogyrae, 447.
— vorax, 447.
Variolaria, 416.
Vegetation, general condi-
tions, 352.
Veines aériféres, 195.
— aquiferes, 195.
Velum, 289, 291.
— partiale, 290.
— universale (volva), 290.
Venae externae, 195.
— internae, 195.
— lymphaticae, 195.
Vermicularia, 252.
— minor, fatty matters, 7.
— —, sclerotium, 41.
Verpa, 189.
Verrucaria, 192, 222.-
—, Algae of thallus, 409.
— carpinea, 246.
— Gibelliana, 246.

THE END.

525

Verrucarieae (Verrucariei),
242.

Verticillium, 245, 249, 252.

Vibrio, 458, 459, 473.

Vibriones, 458.

Volva, 290.

Volvaria, 292, 295, 297.

Warts on compound sporo-
phores, 59.

Water-content, 6.

— -supply, as a condition of
germination, 375.

Whorl of sporidia (Kranz-
körper), 177.

Wine-yeast, 269.

Witches’ brooms, 266, 368,

390.
Withdrawal of water, influ-
ence on germination, 346.
Woronina, 161, 169, 444.
—, parasitism, 395.
Woronin’s hypha, 199, 218.

Xylaria, 186, 192, 199, 236,
244, 260.

—, branching, 51.

— bulbosa, sclerotium, 41.

—, compound sporophores,
development, 56.

— —, growth, 50, 51.

— pedunculata, structure of
spores, 102.

— —, chemical behaviour of
spore-membrane, 105.

— polymorpha, development
of sporophore, 216*.

— —, development of spores,

78.
Xylarieae(Xylariei),186,236,
248, 260.
—, discharge of spores, 97.
Xyloma, 43, 190.
Xylostroma, 22.

Yeast-fungi, 4*, 5, 267, 270,
358.

Yeast-fungus of alcoholic
fermentation, 267.

Yeast-mucilage, 10.

Zeora, 223.

Zoogloea, 457, 459.
Zoospores, 107.
Zygochytrium, 146, 151, 169.
— aurantiacum, 156.
Zygomycetes, 132, 145.
—, rest of spores, 345.

—, thallus, 1.

Zygospores, 129, 145.

—, formation, 147.

—, resting state, 344, 345.

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